Non-inducible Atrial Flutter in a Patient with Prior Surgery for Congenital Heart Disease (Example 1): Ablation Based on Substrate Mapping in Sinus Rhythm

Abstract

This is a 27-year-old male patient who at the age of 5 underwent surgical closure of an ostium secundum atrial septal defect using a Dacron patch. One year before the procedure described here, he began complaining of palpitations, with the ECG equivalent of atrial flutter (Fig. 1) of 240 ms cycle length. The P wave morphology was very similar to that of typical atrial flutter, although symmetric negative P waves were present in the inferior leads, instead of the classic “saw-tooth” morphology. Moreover, unlike typical atrial flutter, the P wave morphology in V1 was biphasic, with a predominant negative late component. Initially, the patient refused the procedure and was cardioverted, but the arrhythmia recurred with the same morphology in the following months. Consequently, the patient accepted the procedure and was referred for ablation while on a persistent episode of atrial flutter. The day before the procedure, probably as a result of its prolonged duration, the arrhythmia degenerated into atrial fibrillation. A previous transthoracic echocardiography in sinus rhythm showed no marked dilation of the heart chambers and normal ventricular function. Preprocedure transoesophageal echo cardiogram excluded intracavitary thrombi.