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Nomenclature and Classification of Cardiac Defects

  • M. J. BélandEmail author
  • R. C. Franklin
  • V. D. Aiello
  • L. Houyel
  • P. M. Weinberg
  • R. H. Anderson
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Abstract

For more in-depth research into congenital cardiac disease, such as for multicentric analysis of outcomes or stratification of risk for interventions, there is a need for a uniform and detailed system of nomenclature. The advances in digital technology and communication seen over the last quarter century have facilitated the task of standardization of entry of data and exchange of information.

In this chapter, the authors, as members of the International Society for Nomenclature of Paediatric and Congenital Heart Disease (ISNPCHD), review the principles and challenges of developing a standardized system of nomenclature for congenital heart disease, from the point of view of developing the International Paediatric and Congenital Cardiac Code (IPCCC) and the congenital heart list for the newest iteration of the International Classification of Diseases of the World Health Organization (ICD-11). The authors expand upon certain areas of contention, summarizing some of the discussions that have taken place among those seeking to create a standardized and international system for naming the various lesions encountered in patients presenting with congenital cardiac disease.

Keywords

Cardiac birth defects Cardiac malformations Categorization Classification Congenital heart disease Heart anomalies Heart defects International nomenclature list Nomenclature Nomenclature list Nomenclature system Nomenclature tree Standardization Standardization of names Structural cardiac anomalies 

Introduction and History

It was only in the last century that the study of congenital cardiac malformations began in earnest. It was as recently as 1936 that the distinguished Canadian physician, Maude Abbott, published the Atlas of Congenital Cardiac Disease [1], which represented the first formal system of classification for cardiac defects, although von Rokitansky had previously offered an embryological classification of septal defects [13]. Subsequent to Abbott’s endeavor, in an effort to establish individual hospital-specific databases, centers across the world, using a multitude of languages, developed or adopted different schemes for describing and classifying the congenitally malformed heart. Unfortunately, these disparate systems made it impracticable to conduct detailed interinstitutional and international investigations into congenital heart disease. Perhaps because of this, studies consequently were mainly published based on data originating from single centers. While the International Classification of Diseases (ICD), commissioned and then adopted by the International Statistical Institute in 1893, and now owned by the World Health Organization (WHO), has been used extensively for the compilation of statistics and reports relating to the gamut of human diseases, this system has not contained enough entries to permit detailed international study in the field of congenital cardiac defects. Even the latest versions of the system recently or currently in use, known as ICD-9 and ICD-10, contain only 29 and 73 diagnostic entries, respectively, for congenital problems afflicting the heart – an inadequate number for anything but the most superficial of administrative or epidemiological reports.

For more in-depth research into congenital cardiac disease, such as for multicentric analysis of outcomes or stratification of risk for interventions, there is need for a uniform and detailed system of nomenclature. The advances in digital technology and communication seen over the last quarter century have facilitated the task of standardization of entry of data and exchange of information. Furthermore, the gradual evolution of the English language to the position of the lingua franca for scientific discourse has further aided in the process of standardization. Recognizing the importance of having a uniform, and adequately detailed, system for the nomenclature of congenital cardiac malformations, there have been several efforts in the last several decades to establish broad-based common lists as described using the English language.

The International Paediatric and Congenital Cardiac Code (IPCCC)

In 2000, the outcomes were published of two major initiatives to standardize the classification and nomenclature for congenital heart disease. One was the European Pediatric Cardiac Code created by the coding committee of the Association for European Paediatric and Congenital Cardiology [5], while the other was the classification created by the International Congenital Heart Surgery Nomenclature and Database Project on behalf of the Society for Thoracic Surgeons and the European Association for Cardiothoracic Surgery [9]. The emphasis within the first was on detailed diagnosis, while that of the second was on surgical interventions. In 2002, it was agreed that a newly established International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease should begin discussions to cross-map and refine these two systems. The outcome of these deliberations was to create the International Society for Nomenclature of Paediatric and Congenital Heart Disease (ISNPCHD). Since 2005, the International Society has developed, maintained, and updated thousands of entries that make up the International Paediatric and Congenital Cardiac Code (IPCCC). This list provides names, together with six-digit codes, for all the currently recognized phenotypes of congenital cardiac malformations, along with diagnostic and therapeutic procedures, as well as postprocedural complications. Should new phenotypes be discovered or interventions be developed, then the Nomenclature Working Group of the ISNPCHD is programmed so as to recognize, classify, and code them.

The IPCCC and the International Classification of Diseases

In 2008, the ISNPCHD and the WHO entered upon an agreement to expand the congenital heart disease section of the latest iteration of the International Classification of Diseases, ICD-11, scheduled for publication in 2018. This work in partnership was meant not only to choose and arrange the terms to be included in ICD-11 but also to define these terms and provide synonyms for them. Thanks to this collaboration, the Foundation layer of ICD-11 includes more than four times as many terms related to congenital heart malformations (over 300 entries) compared to ICD-10. The end result of the entire process is a list that is approved by the World Health Organization for international use in ICD-11. It consists of an elaborate subset of the diagnostic terms that are part of the extensive lexicon of the IPCCC, accompanied by definitions for each term, as well as commonly used synonyms and expert commentary on many controversial or ambiguous terms.

Within ICD-11, therefore, the congenital heart community has a standardized list of names suitable for the description of the congenitally malformed heart. The complete list of the International Classification of Diseases, which contains additional terms for noncongenital heart disease, is available on the World Health Organization ICD website. The complete versions of the International Paediatric and Congenital Cardiac Code can be viewed and downloaded at www.ipccc.net.

In this chapter, the authors, as members of the ISNPCHD, review the principles and challenges of developing a standardized system of nomenclature for congenital heart disease, from the point of view of developing the IPCCC and the congenital heart list for ICD-11. The authors describe the structure of the nomenclature tree to help the user navigate through its branches, as well as expanding upon certain areas of contention, summarizing some of the discussions that have taken place among those seeking to create a standardized and international system for naming the various lesions encountered in patients presenting with congenital cardiac disease.

Developing the IPCCC and the ICD-11 List for Congenital Heart Disease: Basic Principles and Their Application

Certain guiding principles were used by the ISNPCHD in developing the IPCCC and the list of congenital heart diseases for the foundation layer of ICD-11 in partnership with the WHO. Ten of these principles are enumerated below with a brief explanation of how these were applied by the ISNPCHD:
  1. 1.

    Naming phenotypes: The purpose of any system of medical nomenclature should be to ascribe a “tag,” be it a name, a number, or series of names or numbers, to all examples of anatomy, physiology, disease processes, or interventions related to the subject at hand. This “tag” should be scientifically accurate and recognized unambiguously by specialists in the field. To be accepted and used universally, the process for selection of names should have international input from health-care workers who represent different areas of expertise in congenital heart disease, so that ultimately any given name, or “tag,” will reflect the same phenotype whether selected by a morphologist, a congenital heart surgeon, or a pediatric cardiologist anywhere in the world. The constitution of the ISNPCHD emphasizes the importance of international representation within the society, stipulating that the society should have a balanced representation from various fields of expertise in congenital heart disease.

     
  2. 2.

    Numerically coding phenotypes: While a given “tag” or term may be expressed in English, the term should be accompanied by a code number to facilitate translation into other languages. For this purpose, every term found in the IPCCC is associated with a six-digit numeric code derived originally, with permission, from the European Paediatric Cardiac Code of the Association for European Paediatric and Congenital Cardiology [6]. For example, the IPCCC term “interrupted aortic arch” was given the code “09.29.31.” As this number can be used internationally to represent the phenotype, data banks throughout the world can more easily be created to examine this entity, no matter the language in which the data are collected. The IPCCC numeric codes appear throughout this chapter following all congenital heart disease terms. By the same token, the WHO has now assigned its own “entity number” to all terms found in the ICD-11 Foundation list, including those provided to the WHO by the ISNPCHD (for e.g., Interrupted aortic arch = 1769930414). In addition, to conform to previous hard copy versions of the International Classification of Diseases, alpha-numeric “tags” have been assigned to a subset of approximately 100 congenital heart disease terms selected from the Foundation for the WHO’s ICD-11 Mortality and Morbidity Statistics (MMS) list (for e.g., Interrupted aortic arch = LA.8B.22), published on 18 June 2018.

     
  3. 3.

    Defining phenotypes: To link accurately a phenotype to a term, it follows that any system used for naming congenital heart lesions should provide definitions for the terms used, thus facilitating the accurate selection of the correct “tag.” Providing definitions for all terms in the congenital heart disease list of ICD-11 was part of the mandate that the ISNPCHD received from the WHO. Thus, definitions for each term appear as part of the lesion entry of ICD-11 along with short commentary, as needed.

     
  4. 4.

    Providing synonyms for phenotypes: Synonyms should be provided within a nomenclature list, again to facilitate the accurate selection of a given “tag” to describe a particular phenotype. A listing of synonyms is also included as part of the lesion entry in ICD-11 for all congenital heart disease terms. For example, the term “atrioventricular septal defect” is considered synonymous with “atrioventricular canal defect,” and both were given the same IPCCC number 06.06.00. In contrast, the term “endocardial cushion defect” was considered a poor synonym by the ISNPCHD ICD-11 development team and is not included in the final WHO ICD-11 listing, as there is currently no mechanism to distinguish poor or controversial synonyms from scientifically acceptable ones. Such poor synonyms can still be found on specifically searching the ICD-11 browser, but they are to be labeled as “obsolete” with the preferred term evident.

    If different spellings exist for a given entity, and are widely accepted, these have been included as synonyms in ICD-11, once again to facilitate data retrieval and coding. This is particularly true for the fairly common differences in spelling between American English and British English, for example, with the term Laevocardia and Levocardia. These are considered synonyms in ICD-11 and are given the same IPCCC code number 02.01.03, and the same WHO entity number in ICD-11(848076902) and ICD-11 MMS tag (LA80.0).

    It can be remarked in the previous chapter (and in this one) that Latin terms have largely been translated into English in a quest for uniformity of language within the lexicon. Yet Latin terms are still in common use in many parts of the world, notably in North America. If a Latin term is commonly used internationally, it has been considered synonymous with the English term for the purposes of ICD-11. Thus, Truncus arteriosus” is equivalent to Common arterial trunk and retains the number 09.01.01, while “Patent ductus arteriosus” is synonymous with Patent arterial duct, with its number continuing to be 09.27.21. Of note in this regard, is that in general no parentheses are allowed within the ICD-11 list. Thus, if a term such as “Truncus Arteriosus (Common arterial trunk)” is listed as such in the IPCCC, signifying that they are identical and used interchangeably in congenital cardiology parlance, one of the terms was consigned to the status of synonym in the ICD-11 entity page.

     
  5. 5.

    Providing abbreviations: While abbreviations may be listed within the nomenclature system in order to facilitate quick retrieval of information, they should not be used without being spelled out within the primary “tag.” Next to each term in ICD-11, there exists a separate entry where commonly used abbreviations are listed, although abbreviations are not used within the terms themselves. There are limited abbreviations in the IPCCC, and when they appear, they always follow the spelled-out version of the term. This is important in the wider medical context where ASD can signify atrial septal defect or autistic spectrum disorder, depending upon the relevant specialist area.

     
  6. 6.

    Developing a nomenclature list in tree or hierarchical form: An ideal standardized system of nomenclature should permit easy storage and retrieval from computerized databases and should have the capacity to be viewed in tree form. The congenital heart malformations in ICD-11 are listed starting with ten all-encompassing Level 1 terms (Table 1). Each Level 1 term is then parsed into finer and finer detail as one travels down the branches of the nomenclature tree to a maximum of six levels.

    In addition, the user should be able to determine the level of detail to be achieved depending on the purpose at hand. Thus, a Level 5 term such as Trabecular muscular ventricular septal defect: midseptal (at one of the outermost branches of the tree) may be coded as such, using its number 07.11.04. If this degree of detail is not needed, the code for Trabecular muscular ventricular septal defect, a Level 4 term with the number 07.11.01, or more simply Ventricular septal defect, a Level 3 term numbered 07.10.00, may suffice for certain database purposes, such as billing. If the information is available, nonetheless, the precision provided in the more specific code will allow the clinician to classify fine anatomical detail.

     
  7. 7.

    Quantitating and qualifying: Quantification or qualification will enhance the clinical relevance of any system of nomenclature and therefore should be included within the system. At times, the severity or size of a lesion is as important as its anatomical detail. While an epidemiologist may consider all ventricular septal defects of a particular type to be equally significant, the clinician may wish to distinguish small from large defects. In many cases, the designation is arbitrary and difficult to define, but the addition of a qualifier term may be imperative to the clinician. This specific addition to a term is known as postcoordination within the ICD-11 development process. Such terms that exist are in the generic Extension Code chapter. While ICD-11, therefore, has some potential for describing the severity of lesions for any disease process, there was no possibility for the ISNPCHD to suggest specific qualifiers for individual congenital heart malformations, where they might be most relevant. Qualifiers are used more expansively, in much greater detail, and with specific linkage, within the IPCCC. The reader is referred to this list for quantifying or qualifying specific congenital heart lesions.

     
  8. 8.

    Avoiding the use of “other”: Entries with the word other, such as other types of right ventricular outflow tract obstruction, should not be used in a nomenclature system, since the use of the word “other” implies that the user knows what other conditions have been enumerated in that specific list. Used in another context, for instance, within a shortened list from the same scheme, the term “other” thereby changes meaning. Following this principle, both the ICD-11 nomenclature list as submitted to the WHO by the ISNPCHD for congenital heart disease and the IPCCC itself have avoided the use of the word “other.” Coders are instructed to use higher-order terms if a particular lesion does not appear in either the Foundation ICD-11 list or within the IPCCC. For example, the very unusual lesion Coronary sinus diverticulum 04.04.15 appears in the IPCCC list but not in ICD-11. The coder using the full listing of ICD-11 is not provided with a code for “Other congenital anomaly of the coronary sinus.” Instead, the broader Level 3 term Congenital anomaly of the coronary sinus 04.04.05 needs to be used when coding for this rare lesion within ICD-11.

     
  9. 9.

    Avoiding nondescriptive classification schemes: Designations such as “type 1” or “class A” should be avoided, as uniform knowledge of the basis of the scheme in question would be necessary to select the correct “tag.” This is particularly true of entities such as Tricuspid atresia 06.01.01 where a number of classification schemes have been put forward in the last century and include types, subtypes, and subgroups involving designations that are used in variable ways. These designations do not occur in the list of congenital heart terms of ICD-11 with the expectation that a root term (Tricuspid atresia 06.01.01) will be coded independently of associated lesions such as Transposition of the great arteries (discordant ventriculo-arterial connections) 01.05.01, these being described and coded separately.

     
  10. 10.

    Avoiding eponyms: Eponyms, such as “Eisenmenger ventricular septal defect,” should be used sparingly, since they may have variable meaning depending on their use, and not all users may know or agree on the true definition of a given eponym. Where eponyms are used in ICD-11, as in the IPCCC, none are followed by a possessive apostrophe and “s.” Therefore, in ICD-11, what may be known to many as Ebstein’s malformation of the tricuspid valve will read Ebstein malformation of tricuspid valve.

     
Table 1

Level 1 terms in the congenital heart disease list for ICD-11

1.

Congenital anomaly of position or spatial relationships of thoraco-abdominal organs (03.01.13)

2.

Congenital anomaly of an atrioventricular or ventriculo-arterial connection (01.03.09)

3.

Congenital anomaly of mediastinal vein (04.00.07)

4.

Congenital anomaly of an atrium or atrial septum (05.00.02)

5.

Congenital anomaly of an atrioventricular valve or atrioventricular septum (06.00.15)

6.

Congenital anomaly of a ventricle or the ventricular septum (07.00.00)

7.

Functionally univentricular heart (01.01.22)

8.

Congenital anomaly of a ventriculo-arterial valve or adjacent regions (09.04.29)

9.

Congenital anomaly of great arteries including arterial duct (09.04.28)

10.

Congenital anomaly of coronary artery (09.46.03)

Exceptionally, widely recognized eponymous terms, such as Tetralogy of Fallot 01.01.01, appear in ICD-11 as stand-alone terms, but these are accompanied by definitions and synonyms that describe the underlying morphology to facilitate the selection of the correct “tag.”

Other eponymous terms, such as “Taussig-Bing malformation,” have not been eliminated, but instead, appear as synonyms for a root term in ICD-11. Thus, Taussig-Bing malformation has been listed as a synonym for the term Double outlet right ventricle with subpulmonary ventricular septal defect (transposition type) 01.01.18.

Where possible, a succinct description of the anatomical lesion, for example, Left heart obstruction at multiple sites (including Shone syndrome) 01.01.33, has been used in ICD-11 and is bound to be more universally understood, and enduring, than the eponym “Shone’s syndrome” alone.

In addition to the 10 principles used in composing the list of congenital heart disease terms, it should be noted that there are three extra ICD-11 standards which are followed within the lexicon of the World Health Organization. First, the words “and” and “or” in ICD-11 are used with their meanings in formal logic and are not found together as “and/or” or “and-or.” Thus “and” means that both terms must be present in the condition, whereas “or” means that either one, or the other, or both terms may be present. Thus, “or” equates to “and/or” in Table 1 and elsewhere in ICD-11. Second, articles such as “the” are used sparingly in ICD-11. Last, in ICD-11 the plural form of a term in parentheses – for example, “Congenital anomaly of coronary artery(ies)” which appears in the IPCCC – is not allowed in ICD-11, and thus only the singular form is identified, even though a given entry in IPCCC may include both the singular and plural forms of the entity.

Standardized Nomenclature: The Challenges

One of the greatest challenges in developing a standardized list of names is to reconcile and integrate the disparate approaches to describing the phenotypes that have been recognized subsequent to Abbott’s groundbreaking initiative. This is true in particular for the ways of describing lesions as developed in North America, as opposed to Europe. The description of such features as intracardiac connections and alignments, isomerism, double outlet right ventricle, the small chamber in the setting of double inlet left ventricle, and holes between the ventricles continues to be debated. The use of synonyms and definitions within the lexicon, nevertheless, can be effective in reconciling most of the disparate approaches incorporated within the one standardized tree.

A second challenge is that, as the knowledge of embryology and genetics advances, and the understanding of cardiac defects evolves, the names will be subject to revision in order to become more accurate and hopefully to reflect scientific consensus. No currently existing system of nomenclature, therefore, can be considered to represent the final and definitive one, and all systems will need to be maintained and updated over time.

A third challenge is that certain words have, through time and widespread use, become inculcated into the lexicon, despite being scientifically incorrect. For example, “atrial septal defect” has come to represent any kind of interatrial communication, irrespective of whether the communication is across the space normally occupied by the interatrial septum. The term “sinus venosus atrial septal defect” remains in widespread use, even though its diagnostic feature is the presence of a hole outside the confines of the interatrial septum. Recognizing this fact, the term Interatrial communication, with the number 05.04.01, has been adopted as a higher-order term in English to include all lesions that produce the potential for shunting between the atrial chambers. The proper term for Sinus venosus defect, with the number 05.05.00, now falls under the higher order of Interatrial communication, with the number 05.04.01, and not under “atrial septal defect.”

Another challenge is related to the translation of a given list of terms and their associated codes into different languages. It is right and proper that specialists in different countries will use their own languages to describe their findings. The words chosen in one language to translate a particular term from the English language may sound identical but may prove not so. One example is Ventricular septal defect, with the number 07.10.00. This is typically rendered in the Romance languages by words such as “communication interventriculaire,” i.e., an “interventricular communication.” “Communication interventriculaire” has been given the same code as that for “Ventricular septal defect,” namely, 07.10.00. The terms are very similar and, in most cases, do indeed reflect the presence of a hole or breach in the interventricular septum. The term as used in the Romance languages, however, describes the presence of a shunt or communication between the ventricles. This may not exist when an unequivocal defect of the ventricular septum is shrouded by tricuspid valvar tissue, such that there is no potential for shunting across it. Thus, equating “communication interventriculaire” with “ventricular septal defect” with the use of the code 07.10.00 may give subtly different results depending on the language of the user.

Last, one of the biggest challenges in developing a new nomenclature list is that it must serve multiple purposes and must be amenable to being cross-mapped to already-existing large data bases using different nomenclature systems such as the congenital heart surgery databases in North America and Europe. Because individuals from many backgrounds have been involved in the construction of the IPCCC and the ICD-11 congenital heart disease submission to the World Health Organization from its inception, this challenge has largely been overcome.

Nomenclature, the Normal Heart, and Conventions Regarding the Naming of Congenitally Malformed Hearts

Prior to describing the lesions found within the congenitally malformed heart, there needs to be agreement of the optimal way of describing the components making up the normal heart. In the preceding chapter on normal cardiovascular anatomy, the names used for this purpose have been well-defined. This knowledge lays the foundation for the description and nomenclature of the congenitally malformed heart, including three fundamental conventions.

First, when cardiac chambers are described, the qualifiers right and left refer only to the morphological characteristics of the chambers usually designated as being right and left [11]. The qualifiers do not account for their position in the thorax. If a spatial frame of reference is required, then the terms right-sided, left-sided, anterior, and posterior are used. When dealing with cardiovascular structures other than cardiac chambers, in contrast, right and left do refer to the spatial position of these structures within the thorax and not to their morphological counterparts. Thus, the right superior caval vein refers to the caval vein on the right side of the body.

The second convention, established by Van Praagh and his colleagues as the “morphological method,” states that variable features within the heart should be defined in terms of their own intrinsic morphology and not on the basis of other features that are themselves variable [12].

Third, it has been established since the 1960s and 1970s that the segmental approach to describing congenital cardiac abnormalities is fundamental in imparting the full nature of a cardiac defect, particularly when the malformation is complex, and involves multiple cardiac segments. When using this approach, the analyses and descriptions of the malformed heart are made in a logical sequence, permitting the anomalies to be described with precision, and in unambiguous fashion. The heart is approached in terms of three major building blocks: namely, the atriums, the ventricular mass, and the arterial trunks. There is limited potential for variation in each segment. Segmental analysis, therefore, depends upon the recognition of the topologic arrangement of the three cardiac segments.

Two systems of classification have evolved further to describe the malformed heart. The sequential segmental variant of the system, emanating from the so-called European school, combines this topological information with the ways in which the segments are joined, or not joined, to each other (Fig. 1). To avoid ambiguity, the system is designed so that each segment can be described according to how it is linked to the subsequent one, while fully describing each segment, and the nature of the junctional connections.
Fig. 1

The cartoon shows the atrial chambers, the ventricular mass, and the arterial trunks. These are the three segments emphasized as representing the building blocks of the congenitally malformed heart in the original concept of segmental analysis. The subsequent refinements of sequential analysis place additional emphasis on the fashion in which the segments were joined, or not joined, over the atrioventricular and ventriculo-arterial junctions

The alternative classification system, emanating from the so-called Boston School, uses independent descriptions of three major segments: viscero-atrial situs, ventricular loop (see later), and great arterial situs. Adjacent segments are related to each other by intersegmental alignments, which may not equate to connections. In order to facilitate a more concise means of communicating these variants, the Boston School established a system of segmental notation, as detailed in the list below.

Each heart can be described as a three-member subset of the whole with the first member of the set representing viscero-atrial situs; the second, ventricular loop; and the third, great artery situs. Each heart will have a three-letter notation. Thus, in the cases of normal arrangement of cardiac chambers and vessels, the segmental notation is {S,D,S} for viscero-atrial situs solitus, ventricular D-loop, and solitus (normal) relationships of the great arteries in space. These would also be the segments in classical tetralogy of Fallot, and the same segmental notation would apply to classical tricuspid atresia with normally aligned great arteries. Note therefore that intersegmental connections are not classified at this stage and would need to be described separately

Classification by segmental notation with corresponding IPCCC code

Normal cardiac segments {S,D,S}

01.01.70

Segmental nomenclature letter 1 (atrial situs): A = ambiguous (as in isomerism)

01.01.71

Segmental nomenclature letter 1 (atrial situs): I = inversus

01.01.72

Segmental nomenclature letter 1 (atrial situs): S = solitus

01.01.73

Segmental nomenclature letter 1 (atrial situs): X = unknown or not possible to determine

01.01.74

Right hand pattern ventricular topology (D-loop) (segmental nomenclature letter 2: “D”)

02.03.01

Left hand pattern ventricular topology (L-loop) (segmental nomenclature letter 2: “L”)

02.03.02

Ventricular topologic pattern not determinable (segmental nomenclature letter 2: “X”)

02.03.06

Segmental nomenclature letter 3 (relationship of great arteries in space): A = aorta directly anterior to pulmonary artery

01.01.75

Segmental nomenclature letter 3 (relationship of great arteries in space): D = aorta to the right of the pulmonary artery

01.01.76

Segmental nomenclature letter 3 (relationship of great arteries in space): L = aorta to the left of the pulmonary artery

01.01.77

Segmental nomenclature letter 3 (relationship of great arteries in space): S = solitus (normal), meaning ascending aorta crossing right pulmonary artery with mitral-aortic fibrous continuity

01.01.79

Segmental nomenclature letter 3 (relationship of great arteries in space): I = inversus (mirror image of normal), meaning ascending aorta crossing left pulmonary artery with mitral-aortic fibrous continuity

01.01.81

Segmental nomenclature letter 3 (relationship of great arteries in space): X = unknown or not possible to determine

01.01.80

These two schools of classification, depending on strictly segmental analysis, or its sequential variant, still exist with respect to the way in which the cardiac segments are described relative to each other. To set up a tree using segmental analysis, nonetheless, irrespective of the system used, a list of terms can be established, starting from the position and orientation of the heart and following the flow of blood through the heart in a sequential manner from the veins to the arteries as the blood passes through the various segments.

For ICD-11, therefore, the first two sections of Level 1 of the tree were constructed to permit description of the cardiac position and the topology of the various segments, as well as the union, or nonunion, of the cavities within them. There then follow other “first level” entries that delineate the possible abnormalities within each vein or artery, segment, or valve in a sequential manner (Table 1). All of congenital heart disease may be coded using these ten Level 1 terms. For more detailed diagnoses, however, the coder is expected to navigate down the branches of each Level 1 term, to select a more specific description for each phenotype encountered.

It is worthwhile noting that, by definition, ICD-11 is a lexicon of disease. The ISNPCHD chose to include such normal items as Laevocardia (levocardia) (02.01.03) in recognition of the fact that laevocardia in the setting, for instance, of total mirror imagery is an abnormal finding. The same is true for Usual atrial arrangement (atrial situs solitus) (01.03.00), Concordant atrioventricular connections (01.04.00), and Concordant ventriculo-arterial connections (01.05.00), which precede other related anomalies. Within ICD-11, these usually normal findings will be accompanied by a comment describing “This is a normal finding that should be coded only in the context of complex heart disease.”

What follows are further notes regarding the ten Level 1 congenital heart disease sections of ICD-11. An exhaustive discussion of the contents of all ten sections, and their subdivisions, is beyond the scope of this chapter. For the complete list, with commentary, the reader is referred to the chapter on structural congenital heart disease in ICD-11, available on the website of the World Health Organization.

Congenital Anomaly of Position or Spatial Relationships of Thoraco-abdominal Organs (03.01.13)

Identification of the Atriums

Before identifying the manner in which the atriums are joined, or not joined, to the underlying ventricles, an accurate means is required to identify the morphologically right as opposed to the morphologically left atrium. The most reliable feature of an atrium that will serve to distinguish the morphologically right as opposed to the morphologically left features is the extent of the pectinate muscles relative to the atrioventricular junctions, as discussed in the previous chapter on the normal anatomy of the heart. Thus, upon inspection of the atrial appendages, whether by echocardiography, magnetic resonance imaging, computed tomography, or directly during surgery or at autopsy, it is usually possible to distinguish between morphologically right as opposed to morphologically left features.

Ventricular Spatial Relationships

Even in the normal heart, the spatial relationships of the inlet, apical, and outlet components of the ventricles are complex. Unlike the atrial chambers, which are almost always side-by-side, the ventricles may be deviated in anteroposterior or supero-inferior fashion. Despite these spatial changes, when normally constituted they will still display one of two internal spatial organizations or “loops.” These patterns are best considered as “D” or “L,” or right-handed or left-handed, enantiomers. Thus, by focusing on the inflow and outflow components as assessed from the stance of the septum, it is possible to attribute chirality, or handedness, to the ventricular spatial organization. If it is the right hand that can be placed in the morphologically right ventricle in such a way that the palm of the hand lies against the septal surface, with the thumb in the right ventricular inflow, and the fingers pointing toward the outflow, then there is a D-loop arrangement of the ventricles, or right-handed topology, described in ICD-11 as Right hand pattern ventricular topology (D-loop) 02.03.01, a third-level term in this first section of Level 1 terms. If it is the left hand that fits the morphologically right ventricle in this fashion, with the thumb in the inlet, the fingers toward the outlet, and the palm against the septum, the ventricles are L-looped, with left-handed topology, i.e., Left hand pattern ventricular topology (L-loop) 02.03.02 in ICD-11. Since a right hand can always be distinguished from a left one, it follows that D-looped ventricles should not be mistaken for L-looped ventricles, regardless of the position of the heart, or the ventricles, in three-dimensional space. In persons with usually arranged atriums and discordant atrioventricular connections, the ventricles are almost always L-looped, showing a left-handed topological pattern, whereas D-looped ventricles, with a right-handed topological pattern, are usually found with the combination of mirror-imaged atriums and discordant atrioventricular connections.

Heterotaxy

Visceral heterotaxy (abnormal arrangement of thoraco-abdominal organs) (03.01.02) is further divided into the two most commonly recognized subsets of Right isomerism (“asplenia syndrome”) (03.01.04) and Left isomerism (“polysplenia syndrome”) (03.01.05).

By convention, Visceral heterotaxy has been defined to exclude patients with totally mirror-imaged arrangement of the thoracic and abdominal organs along the left-right axis, even though this arrangement is heterotaxic in being other than normal. In the case of Total mirror imagery (Situs inversus totalis) 03.01.03, the lungs, abdominal organs, and heart are simply the mirror image of the usual arrangement. Should there be associated anomalies of the lungs and abdominal organs, this will be specific to the given organ, rather than reflecting its mirror-imaged location.

In patients with lateralized arrangements of the thoraco-abdominal organs, in other words with either the usual or mirror-imaged patterns, it is exceedingly rare to have disharmony between the locations of the organs. In these settings, therefore, the liver is anticipated to be on the same side as the morphologically right atrium, with the spleen and stomach on the side of the morphologically left atrium. In contrast, when the atrial appendages are isomeric, that is, a heart with bilateral morphologically left, or bilateral morphologically right, atrial appendages, then almost always the abdominal organs are jumbled up. Most, but not all, patients with isomeric appendages will either lack a spleen or have multiple spleens. In circumstances where the arrangement is unusual, and there is obvious disharmony between the arrangement of the thoracic and abdominal structures, this can be dealt with by coding as much as is known about the precise location of the individual organs, after coding the higher-level term Visceral heterotaxy (abnormal arrangement of thoraco-abdominal organs) (03.01.02).

Congenital Anomaly of an Atrioventricular or Ventriculo-Arterial Connection (01.03.09)

Congenital anomalies of cardiac connections are those in which the atrial chambers do not make union with the ventricular mass nor the arterial trunks arise from the ventricular mass, in the fashion anticipated for the normal heart. With respect to the atrioventricular junctions, there may be either biventricular or univentricular atrioventricular connection(s). As the latter is invariably associated with a functionally univentricular heart (either double inlet or an absent atrioventricular connection), for the purposes of ICD-11, these have been grouped together within Sect. 7 of Level 1 terms, “Functionally Univentricular Heart (01.01.22),” and thus are not listed in section “Anomaly of an Atrioventricular and/or Ventriculo-Arterial Connection (01.03.09).”

Discordant Atrioventricular Connections (01.04.01)

By definition, this arrangement exists when the right and left atriums are joined in morphologically inappropriate fashion to the underlying ventricles. Such discordant atrioventricular arrangements can be found in the settings of either a usual or mirror-imaged atrial arrangement. When the atrial appendages are mirror imaged in patients with discordant atrioventricular connections, the ventricular mass typically shows right-handed topology or “D-looping.” When there are isomeric atrial appendages, it is impossible for there to be either concordant or discordant atrioventricular connections. Instead, the union across the atrioventricular junctions is biventricular and mixed. Full description, as is available in the IPCCC, then requires specification of the type of isomerism and the ventricular topology present. It may also require a full description of the veno-atrial connections, since some patterns of venous return may give the false impression of usual or mirror-imaged atrial arrangement.

Congenitally Corrected Transposition (01.01.03)

Congenitally corrected transposition, meaning discordant atrioventricular & ventriculo-arterial connections, was given in its own code and included at this level, despite the fact that the malformation consists of a combination of anomalies of cardiac connection. This was done because of its widely recognized nature as a unique form of congenital heart disease and one that is known to be associated with other problems. These include coexisting ventricular septal defects, obstruction of the morphologically left ventricular outflow tract, anomalies of the morphologically tricuspid valve, and anomalies of atrioventricular conduction.

Transposition of the Great Arteries (01.05.01)

The ventriculo-arterial connections are discordant whenever the aorta arises from the morphologically right ventricle, or its rudiment, and the pulmonary trunk arises from the morphologically left ventricle or its rudiment.

Further to classify the entry Transposition of the great arteries in the setting of concordant atrioventricular connections, three combination terms, or “molecules,” are exceptionally included in the ICD-11 list, because of the implications for risk stratification. Some “molecules” have been given a single numeric code, whereas others may be represented by as many individual codes as there are “atoms” in each entry:

Transposition of the great arteries with concordant atrioventricular and discordant ventriculo-arterial connections and intact interventricular septum (01.01.02)

Transposition of the great arteries with concordant atrioventricular connections and ventricular septal defect (01.01.10)

Transposition of the great arteries with concordant atrioventricular connections and ventricular septal defect and left ventricular outflow obstruction (01.01.10 + 07.09.01)

Concordant Ventriculo-Arterial Connections with Parallel Great Arteries (01.05.10)

Concordant ventriculo-arterial connections with parallel great arteries, also known as “anatomically corrected malposition,” are rare lesions with two salient features, namely, a left ventricular infundibulum and intrapericardial arterial trunks that arise from morphologically appropriate ventricles and extend into the mediastinum in parallel rather than spiraling fashion. It was included in this section because of the unusual connection of the left ventricle with the aorta, with the resultant abnormal disposition of the great arteries.

Double Outlet Right Ventricle (01.01.04)

Double outlet right ventricle is found when both arterial roots arise in their entirety, or predominantly, from the morphologically right ventricle. Since the designation “predominantly” is rather arbitrary, different rules for assigning great arteries to ventricles have evolved over time. Some controversy still exists, therefore, as to the criteria necessary to make the diagnosis of “double outlet right ventricle.”

One school argues that overriding arterial valves, from the stance of their ventricular origin, be assigned to the ventricle supporting the greater parts or more than 50% of their circumference.

Another school puts forward that, because of the natural aortic override of the curved portion of the interventricular septum in the normal heart, irrespective of the fact that the normal aorta, of necessity, is supported exclusively within the left ventricle, the 50% rule would only hold in the absence of fibrous continuity between the aortic and mitral valves. In the presence of aorto-mitral continuity, the aorta would be assigned to the left ventricle no matter how much it overrides the interventricular septum. This same school holds that, in contrast, for the case of pulmonary to mitral valve continuity, the 50% rule should be used to assign the pulmonary artery to a ventricle, since in the normal heart the pulmonary valve sits entirely over the right ventricular cavity and no natural pulmonary valvar “override” of the interventricular septum occurs.

The relationship of the great vessels predominantly to the right ventricle notwithstanding, some would insist that double outlet right ventricle should only be diagnosed in the presence of bilateral infundibulums. Nonetheless, it is a fact that such bilateral infundibulums can also be found when the ventriculo-arterial connections are concordant or discordant, while both arterial trunks can arise exclusively from the right ventricle in the presence of arterial-to-atrioventricular valvar fibrous continuity. It is a consideration of cases such as this that demonstrates the importance of the “morphological method,” wherein variable cardiac features should be defined in terms of their intrinsic morphology, precluding other features that are themselves variable.

Irrespective of how it is defined, once the diagnosis of double outlet right ventricle has been made, it has traditionally been subclassified according to the relationship of the hole between the ventricles to the most proximate great artery. The hole can be positioned in subpulmonary, subaortic, doubly committed, or noncommitted locations. Attention has recently been drawn to the distinction between the overlapping concepts of “ventricular septal defect” and “interventricular communication” in the setting of double outlet right ventricle [2]. It is the exit from the left ventricle that provides the interventricular communication (Fig. 2a). This hole, however, does not represent the defect in the ventricular septum as usually defined, for example, in the setting of tetralogy of Fallot. In the latter situation, it is the cranial continuation of the plane of the apical muscular ventricular septum that represents the true plane of interventricular separation (Fig. 2b). To be accurate in describing the lesion, therefore, it may be necessary to distinguish between an interventricular communication and a ventricular septal defect (Fig. 3). This, of course, is in contrast to the setting of a typical “isolated” ventricular septal defect without evidence of septal malalignment, when the two terms are in general synonymous. Surgeons have indirectly positioned themselves in the debate by describing operations to repair patients with holes between the ventricles in two ways, depending on the lesion. Thus, the surgeon may simply describe closure of a ventricular septal defect with a patch. Alternatively, the surgeon may have considered it necessary to create a tunnel between the left ventricle and an arterial root. Depending on the option chosen, the surgeon will either have closed a ventricular septal defect or rerouted an interventricular communication.
Fig. 2

The images show, to the left hand, the right ventricular outlets in the setting of double outlet right ventricle and, to the right hand, a comparable image of tetralogy of Fallot. In double outlet right ventricle, the hole between the ventricles (red dotted line) is the outlet for the left ventricle. The yellow dotted line shows the plane of deficient ventricular septation. It is the line shown by red that is usually described as the ventricular septal defect. To the right hand, the yellow dotted line shows the plane of deficient ventricular septation. In tetralogy, however, it is this plane that is usually described as the ventricular septal defect. It is different from the plane labeled as such in double outlet right ventricle. In the right hand panel, the green dots show the plane of interventricular separation, which is the cranial continuation of the long axis of the muscular apical ventricular septum (see Fig. 3)

Fig. 3

The cartoon shows the planes that exist with the cone of space subtended between the leaflets of an overriding arterial valve, such as the aortic valve in tetralogy of Fallot, and the crest of the apical muscular ventricular septum. The double-headed green arrow is the plane of interventricular separation, the geometric interventricular communication. The yellow double-headed arrow shows the plane of deficient ventricular septation when the muscular outlet septum is deviated so as to be contained within the right ventricle. This is the plane usually described as the ventricular septal defect in the setting of tetralogy of Fallot (see right hand panel of Fig. 2). The red double-headed arrow is the outlet from the left ventricle. This is the plane of interventricular separation in double outlet right ventricle and hence the interventricular communication (see left hand panel of Fig. 2). In double outlet right ventricle, however, the hole is usually described as the ventricular septal defect. It is different from the hole described in this fashion in the setting of tetralogy of Fallot. Note that the same planes would also be apparent in the presence of an overriding pulmonary trunk in the setting of the spectrum of transposition of the great arteries with a ventricular septal defect and double outlet right ventricle with a subpulmonary “ventricular septal defect”

For the purposes of ICD-11, four main subtypes of “double outlet right ventricle” have been retained. Following the discussion above pertaining to the communication between the two ventricles in double outlet right ventricle, and knowing that there is no, as of yet, universal agreement of this line of reasoning, additional synonyms for each of the subtypes have been submitted, while retaining the same numerical code to ensure that the various phenotypes are identified and coded accurately:

Double outlet right ventricle with subaortic or doubly committed ventricular septal defect and pulmonary stenosis (Fallot type) or Double outlet right ventricle with subaortic or doubly committed interventricular communication and pulmonary stenosis (Fallot type) (01.01.17)

Double outlet right ventricle with subpulmonary ventricular septal defect (transposition type) or Double outlet right ventricle with subpulmonary interventricular communication (transposition type) (01.01.18)

Double outlet right ventricle with noncommitted ventricular septal defect or Double outlet right ventricle with noncommitted interventricular communication (01.01.19)

Double outlet right ventricle with subaortic or doubly committed ventricular septal defect without pulmonary stenosis (ventricular septal defect type) or Double outlet right ventricle with subaortic or doubly committed interventricular communication without pulmonary stenosis (ventricular septal defect type) (01.01.40)

An additional code, Double outlet right ventricle with intact ventricular septum (01.01.24) was also included in ICD-11, such as may be found in the setting of mitral atresia or rarely with biventricular atrioventricular connections.

Common Arterial Trunk (09.01.01)

Common arterial trunk (truncus arteriosus) is a congenital cardiovascular malformation in which a solitary arterial trunk arises from the heart, giving origin sequentially to the coronary arteries, one or both pulmonary arteries, and part or all of the systemic arterial circulation. Hearts with common arterial trunks were formerly classified into types I through IV, depending on the origin of the pulmonary arteries. In ICD-11, the malformation is classified as to whether the aortic or pulmonary portion of the trunk dominates, recognizing also that, rarely, there can be a balanced arrangement of the aortic and pulmonary components, which would default to the higher-level term of Common arterial trunk (09.01.01). The nomenclature that was chosen is more descriptive, aiming to remove ambiguity and avoid confusion. In addition, attributes of the truncal valve were coded in this section:

Common arterial trunk with aortic dominance (09.01.15):
  • Common arterial trunk with aortic dominance and both pulmonary arteries from trunk (09.01.14)

  • Common arterial trunk with aortic dominance and one pulmonary artery absent from trunk, isolated pulmonary artery (09.01.11)

Common arterial trunk with pulmonary dominance and aortic arch obstruction (09.01.12):
  • Common arterial trunk with pulmonary dominance and interrupted aortic arch (09.01.18)

  • Common arterial trunk with pulmonary dominance and aortic coarctation (09.01.19)

Atypical truncal valve (09.02.10)

Congenital truncal valvar regurgitation (09.02.19)

Congenital truncal valvar stenosis (09.02.18)

Dysplasia of truncal valve (09.02.01)

Congenital Anomaly of Mediastinal Vein (04.00.07)

Systemic Venous Abnormalities

Congenital anomalies of the mediastinal veins include those involving the systemic and pulmonary venous circulations. On the systemic side, these were divided into those affecting the superior caval vein, the inferior caval vein, and the coronary sinus. The descriptors for the caval venous malformations are relatively straightforward.

Pulmonary Venous Abnormalities

As far as the pulmonary venous anomalies are concerned, the international committee has discussed the use of the adverbs “totally” and “partially,” as opposed to the adjectives “total” and “partial,” when accounting for the types of anomalous pulmonary venous connections. Grammar dictates use of the adverb, but the debate has yet to be resolved, and both versions are considered synonymous in ICD-11.

Scimitar Versus Scimitar Syndrome

The word “Scimitar” was retained, with the understanding that the definitions and distinction between Partial anomalous pulmonary venous connection of Scimitar type (01.01.16) and Scimitar syndrome (03.02.23) are well known and difficult to describe succinctly. The partially anomalous pulmonary venous connection associated with the scimitar finding consists of a congenital cardiovascular malformation in which some of the pulmonary veins, usually the right pulmonary veins, connect anomalously to the inferior caval vein, or to the right atrium at its junction with the inferior caval vein. The Scimitar syndrome is diagnosed when the congenital cardiopulmonary malformation coexists with other lesions, such as hypoplasia of the right lung with bronchial anomalies, a right-sided heart, hypoplasia of the right pulmonary artery, and anomalous systemic arterial supply to the lower lobe of the right lung directly from the aorta or its main branches.

Congenital Anomaly of an Atrium or Atrial Septum (05.00.02)

Interatrial Communications

As has already been emphasized, not all interatrial communications occur through the area that, in the normal heart, is formed by the atrial septum. Properly speaking, an “atrial septal defect” would be a hole in the area occupied by the atrial septal structures, which include the floor of the oval fossa and its muscular anteroinferior rim. Such true atrial septal defects are more commonly referred to as “secundum defects.” In this respect, they should properly be described as ostium secundum defects, since the part of the septum that is deficient, the flap valve, is derived from the primary atrial septum. To remove all traces of ambiguity, this entity is better described as an Atrial septal defect within oval fossa (05.04.02), with the synonym secundum atrial septal defect. There are, of course, other communications that permit interatrial shunting. Five are included in Level 4 of this part of the list, under the title (or Level 3 term) Interatrial communication. Patent oval foramen (patent foramen ovale) (05.03.01) is listed here as an interatrial communication, even though there is normally only the potential for shunting through the foramen. The channel may be closed with a transcatheter device when implicated as a causal mechanism for right-to-left shunting in the setting of an embolic cardiovascular accident or stroke. The so-called “primum defects” (Partial atrioventricular septal defect with isolated atrial component and Common atrium with common atrioventricular junction) have as their phenotypic feature a common atrioventricular junction. These lesions, therefore, are included in the next section “Congenital Anomaly of an Atrioventricular Valve or Atrioventricular Septum (06.00.15).”

Right or Left Juxtaposition of the Atrial Appendages

Juxtaposition of the atrial appendages refers to that condition in which both atrial appendages, or one appendage and part of the other, lie beside each other, and to one or other side of the arterial pedicle [3]. It is incorrect to refer to this anomaly as “juxtaposition of a morphologically right, or left, atrial appendage,” since the word juxtaposition refers to the location of the two appendages relative to the arterial pedicle and not the location of the specific appendage. Thus, ICD-11 contains the entries: Left-sided juxtaposition of the atrial appendages 05.01.06 and Right-sided juxtaposition of the atrial appendages 05.02.04.

Supravalvar or Intravalvar Mitral Ring (05.02.02)

While supravalvar mitral rings could have been coded in the section on anomalies of the left atrium, in ICD-11 it is found in the next section dealing with atrioventricular valves.

Congenital Anomaly of an Atrioventricular Valve or Atrioventricular Septum (06.00.15)

This section is divided in two parts: the first involving hearts having two atrioventricular valves and the second those with a common atrioventricular junction. Defined as a defect of the atrioventricular component of the membranous septum, the term Communication between left ventricle and right atrium (Gerbode defect) 07.14.02 appears in this section as well and not in the section on ventricular septal defects.

In the classification of mitral valvar anomalies, the entry True cleft of anterior mitral leaflet (without common atrioventricular junction) 06.02.36 refers to the presence of a split within one of the leaflets of the morphologically mitral valve, usually the anterior or aortic one, with the cleft usually dividing the leaflet in two. Such clefting can occur in otherwise normal hearts or in hearts that are themselves malformed by additional septal defects or abnormal connections. In morphological terms, however, it is incorrect to consider the space between the left ventricular components of a common atrioventricular valve as representing a “cleft mitral valve.” The space seen when there is a common atrioventricular junction is the zone of apposition between the left ventricular components of the leaflets that bridge the ventricular septum, with the left half of the common valve having no resemblance to the episcopal miter, even in the so-called partial variants characterized by an isolated ostium primum defect. When seen echocardiographically, the two entities are markedly different. The cleft of the anterior leaflet of an otherwise normal mitral valve points into the left ventricular outflow tract or toward the subpulmonary interventricular communication if associated with double outlet right ventricle. The zone of apposition between the left ventricular components of the bridging leaflet of a common atrioventricular valve points toward the nadir of the scooped-out ventricular septum [10].

Common Atrioventricular Junction (06.06.11)

Atrioventricular septal defects have long been classified into “complete,” “partial,” and “intermediate”/“transitional” without a commonly agreed-upon definition for each. In ICD-11, the descriptors used for each item were purposefully detailed to make the terms as unambiguous as possible. Thus, what is known to some as a “Partial atrioventricular septal defect” is described in ICD-11 as Atrioventricular septal defect with communication at the atrial level only (06.06.01). This indicates that the lesion includes all the components typically associated with an atrioventricular septal defect in the setting of a common atrioventricular junction except for shunting through the defect at the ventricular level. This does not exclude the possibility of having an interventricular communication at other levels, such as through a ventricular septal defect in the trabecular muscular portion of the septum. Such a muscular ventricular septal defect, along with other lesions outside of the atrioventricular septal defect, if present, would need to be coded separately.

Atrioventricular Valve Atresia

Atresia of the atrioventricular valves is not included in this section. This is because the lesion is most frequently produced by the absence of either the right- or left-sided atrioventricular connection. Even if the atresia is the consequence of an imperforate valvar orifice, the result is to produce a functionally univentricular heart. All of these latter lesions, therefore, are grouped together with those characterized by double inlet ventricle in the section devoted to “Functionally Univentricular Heart (01.01.22),” below.

Congenital Anomaly of a Ventricle or Ventricular Septum (07.00.00)

Tetralogy of Fallot 01.01.01 and congenital obstruction of the right and left ventricular outflow tracts are listed here, whereas Double outlet right ventricle is to be found in the section “Congenital Anomaly of an Atrioventricular or Ventriculo-arterial Connection,” even though by some definitions both arterial trunks can arise exclusively from the right ventricle in the setting of tetralogy. Hearts with subpulmonary and subaortic stenosis are listed in the section “Congenital Anomaly of a Ventriculo-Arterial Valve or Adjacent Regions (09.04.29).”

Ventricular Septal Defect (07.10.00)

The definition, nomenclature, and classification of holes between the ventricles, also known as ventricular septal defects and/or interventricular communications, have been a source of much debate since the 1980s and continue to be debated. Most have defined such holes from the perspective of the right ventricle. This has been achieved by dividing the right ventricular aspect of the ventricular septum into regions, describing holes within these regions as subtypes of the lesions providing the potential for interventricular shunting, while noting key landmarks such as the location of the tricuspid and arterial valves. Two systems of classification for ventricular septal defects, the so-called “geographic” versus “borders” approaches, have dominated this debate.

The “geographical” approach, emanating originally from Boston, primarily classifies the defects according to their location within the septum, particularly noting the key landmarks of the “Y”-shaped septal band, the infundibular and muscular septums, and the tricuspid valvar annulus. In the system, there are five subtypes, namely, the conoventricular, conal septal malalignment, inlet or atrioventricular canal type, conal septal hypoplasia, and muscular defects.

Emanating mostly from Europe, the alternative “borders” approach describes defects primarily with respect to the boundaries or margins of the defect. Distinction is made between those abutting the area of fibrous continuity between the atrioventricular and arterial valves, so-called perimembranous defects, those roofed by the arterial valves when in fibrous continuity to each other, and described as being sub- or juxta-arterial, and those entirely bounded by the muscular components of the septum or muscular defects. The defects are then further classified according to their position in relation to the components of the right ventricle, in other words, whether they open to the inlet, apical trabecular (apical), or outlet parts of the right ventricle. A further descriptor is then used if there is additional malalignment between the septal components.

The two approaches have different frames of reference, and there are, therefore, only a limited number of exact synonyms for the same morphological phenotype. It is not within the scope of this chapter to resolve these debates definitively. The ICD-11 classification of ventricular septal defects attempts to provide definitions and sufficient synonyms to permit the choice of a specific code for a given phenotype, regardless of which scheme is being used. The reader is referred to a detailed report summarizing the controversies surrounding the classification of ventricular septal defects [8].

Of note, the inlet component of an atrioventricular septal defect is purposefully excluded from this section, since as already discussed, it is listed within the classification offered for atrioventricular septal defects, the section “Congenital Anomaly of an Atrioventricular Valve or Atrioventricular Septum (06.00.15).” The combination term Atrioventricular septal defect and tetralogy of Fallot (01.01.20) and the term Communication between left ventricle and right atrium (Gerbode defect)(07.14.02) are also listed in section “Congenital Anomaly of an Atrioventricular Valve or Atrioventricular Septum (06.00.15)” and not in this section.

Due to its frequency in clinical practice, a single physiological category has also been added to the ICD-11 list of congenital anomalies of the ventricular septum that of the hemodynamically insignificant ventricular septal defect, Ventricular septal defect hemodynamically insignificant (07.15.01).

For describing the interventricular communications that define the different types of double outlet right ventricle, the reader is referred to the section “Congenital Anomaly of an Atrioventricular or Ventriculo-Arterial Connection (01.03.09).”

Functionally Univentricular Heart (01.01.22)

The term “functionally univentricular heart” describes a spectrum of congenital cardiovascular malformations in which the ventricular mass may not readily lend itself to partitioning in a way that commits one ventricular pump to the systemic circulation and the other to the pulmonary circulation. Common lesions in this category include double inlet ventricle, atrioventricular valvar atresia, and the hypoplastic left heart syndrome. Although widely used, the term “single ventricle” should be avoided and is not used in the IPCCC or in ICD-11. It is a misnomer, since in most examples rightly coded as functionally univentricular hearts, there is a hypoplastic or incomplete second ventricle present. Hearts with a truly solitary ventricle do exist. In these lesions, which are exceedingly rare, the solitary chamber has indeterminate apical trabeculations and should be designated: Double inlet to solitary ventricle of indeterminate morphology (01.04.05).

Congenital Anomaly of a Ventriculo-Arterial Valve or Adjacent Regions (09.04.29)

Upon inspection of this section of the IPCCC list, but not in ICD-11, it will not go unnoticed that, when describing the aortic and pulmonary valves, the term “annulus” appears with quotation marks. This is because, unlike the atrioventricular valves, the leaflets of the arterial valves are hinged in semilunar rather than circular fashion. The plane of space usually described by echocardiographers as the “annulus” has no anatomic counterpart. Rather, it is the virtual plane created by placing lines between the most proximal, or caudal, points of attachment of the valvar leaflets. There is a more obvious true ring found between the distal, or cranial, attachments of the valvar leaflets and the commencement of the tubular components of the arterial trunks. This is the sinotubular junction, which is an integral part of the arterial valvar mechanism. The so-called “supravalvar” obstruction typically involves this junction.

Note is made that the truncal valve, although an arterial valve and a candidate for inclusion in this section, falls under Common arterial trunk (09.01.01) that is found in the section “Congenital Anomaly of an Atrioventricular or Ventriculo-Arterial Connection (01.03.09).”

Congenital Anomaly of Great Arteries Including Arterial Duct (09.04.28)

Various names used in this section have the potential to create ongoing discussions. The pulmonary trunk is the name favored by anatomists, and the one recommended in the “Terminologia anatomica,” for the channel often described by pediatric cardiologists as the “main pulmonary artery”, now listed as a synonym. There are further advantages to be gained when describing the pulmonary trunk, since usage in this fashion permits its branches to be named as the right and left pulmonary arteries, avoiding additional tautologous use of “branch,” as in “right and left branch pulmonary arteries.”

The term “hemitruncus” has not been included in the lexicon. The appropriate term for this entity is anomalous aortic origin of the right or left pulmonary artery, while hemitruncus is listed as a synonym.

In this section of ICD-11, there is a relatively short list of lesions included under the overall heading of the “Tracheo-oesophageal Compression Syndrome (09.31.40).” Also known as vascular rings and slings, there are multiple variations that produce such compression, but all are well understood on the basis of the hypothetical double aortic arch as initially described by Edwards and his colleagues [4]. These are more fully enumerated in the IPCCC.

Congenital Anomaly of Coronary Artery (09.46.03)

The list of coronary arterial anomalies in ICD-11 is designed to cater to the arterial trunks as found in the otherwise normal heart. Note that, from the anatomical viewpoint, the coronary artery usually called the “left anterior descending artery” is more correctly described as the “anterior interventricular artery.” Both terms, therefore, have been entered into ICD-11 as synonyms. The authors have continued to use the term “pulmonary trunk” as a synonym for “main pulmonary artery,” so that the suggested acronym for the Bland-Garland-White syndrome becomes ALCAPT (Anomalous origin of left coronary artery from pulmonary trunk), as opposed to the more frequently quoted ALCAPA (Anomalous origin of left coronary artery from pulmonary artery). Again, both synonyms are acceptable alternatives, having the same international code (09.41.03). Several of the lesions nominated above account for abnormal sinusal origin of one of the coronary arteries in hearts with concordant ventriculo-arterial connections.

Diverse sinusal origin, of course, is well recognized in the setting of transposition or double outlet right ventricle with subpulmonary interventricular communication. A detailed description of the variations in coronary arterial origins is important for the surgeon preparing to perform the arterial switch procedure. The key in making these descriptions is to distinguish between the two aortic sinuses that are adjacent to the pulmonary trunk and which usually give rise to the coronary arteries. It is exceedingly rare for a coronary artery to arise from the aortic sinus that is not adjacent to the pulmonary trunk, in which case the higher-level term would therefore be used for coding purposes. Thus, one can readily identify and label the two facing sinuses of the aorta as left and right facing or anterior and posterior facing. Another method to identify the aortic sinuses in transposition uses what is known historically as the Leiden Convention [7]. This method locates the two adjacent aortic sinuses and distinguishes them from the stance of a hypothetical observer standing in the nonadjacent sinus of the aorta and looking toward the pulmonary trunk. One of the sinuses will be to his or her right hand. This is now known as sinus number 1. The other sinus will be to the left hand and is known as sinus number 2. The disadvantage of using the Leiden nomenclature system, however, is that the coder needs to be aware of the details of the convention. As mentioned earlier, when discussing the principles of developing nomenclature lists, nondescriptive “tags” that use numerical notations within a term are to be avoided. A detailed and descriptive classification of coronary artery origins in abnormal ventriculo-arterial connections is available in the IPCCC but not in ICD-11.

Summary: ICD-11 List of Terms for Congenital Heart Disease

In ICD-11 (Foundation), more than 320 terms have been compiled to name the phenotypes that represent congenital heart disease, with the terms then listed in hierarchical tree form, following a sequential segmental approach. For ease of identification, the coder is provided, as appropriate, with definitions, synonyms, alternate spellings, abbreviations, and commentary for each term. In ICD-11 (Foundation), there is also an available listing of acquired abnormalities of the heart that relate to congenital heart malformations, such as postprocedural complications and endocarditis, as well as noncongenital cardiac disease found in children, such as an extensive list of various types of cardiomyopathies and arrhythmias.

Since 2018, the list is available free of charge on the website of the World Health Organization in the section reserved for ICD-11 (Foundation). A subset of approximately 100 of these terms has been retained by the WHO for the ICD-11 MMS list used to compile mortality and morbidity statistics internationally.

Conclusion

The provision of the list of over 300 terms for the description of structural congenital heart disease, incorporated within the eleventh iteration of the International Classification of Disease (ICD-11), will hopefully produce a system that provides sufficient specificity for clinicians and surgeons properly to code the myriad lesions encountered in their patients with congenitally malformed hearts. The rapidly emerging evidence regarding the steps involved in normal and abnormal development of the heart is now permitting more precise correlations to be made with regard to morphogenesis. These, in turn, are providing greater insights into the structure of some lesions that remain controversial. As has been emphasized in the initial sections of this chapter, no system can be considered to be graven in stone, and provisions have been made to enable ongoing modifications to the list to take place as needed. The diagnostic nomenclature that has been incorporated into the eleventh iteration of the International Classification of Diseases (ICD-11), nonetheless, represents a significant step in the ultimate goal to create a universally acceptable and available system for naming the lesions found when the heart is congenitally malformed.

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Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2020

Authors and Affiliations

  • M. J. Béland
    • 1
    Email author
  • R. C. Franklin
    • 2
  • V. D. Aiello
    • 3
  • L. Houyel
    • 4
  • P. M. Weinberg
    • 5
  • R. H. Anderson
    • 6
  1. 1.Division of Pediatric CardiologyThe Montreal Children’s Hospital of the McGill University Health CentreMontrealCanada
  2. 2.Paediatric Cardiology Directorate, Royal Brompton & Harefield NHS TrustLondonUK
  3. 3.Laboratory of Pathology, Heart Institute (InCor)University of Sao Paulo Medical SchoolSao PauloBrazil
  4. 4.Medico-surgical Unit, Congenital and Paediatric Cardiology, Necker Hospital, Paris Descartes UniversityParisFrance
  5. 5.The Children’s Hospital of Philadelphia and Perelman School of Medicine at University of PennsylvaniaPhiladelphiaUSA
  6. 6.Biosciences InstituteNewcastle UniversityLondonUK

Section editors and affiliations

  • Dunbar Ivy
    • 1
  • Eduardo M. da Cruz
    • 2
  1. 1.Dept. Pediatric CardiologyChildren's Hospital Colorado, Univ. of Colorado, DenverAuroraUSA
  2. 2.The Heart Institute, Department of PediatricsChildren’s Hospital Colorado, University of Colorado School of MedicineAuroraUSA

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