Emergency Treatment of Bradycardic and Tachycardic Arrhythmias
Cardiac arrhythmic disorders are defined as bradycardia or tachycardia on the basis of ventricular response that is less than 60 b/m for bradyarrhythmias and more than 100 b/m for tachyarrhythmias. Arrhythmias are a common cause of syncope and must be considered in all patients in whom syncope occurs, particularly when cardiac disease is present. Either extreme of ventricular rate, bradycardia or tachycardia, can depress cardiac output to the point of critical hypotension and syncope. Cerebral blood flow is well maintained in supine, healthy individuals over a wide range of heart rates, from approximately 35 to 190 beats for minute. Pulse rates outside this range may reduce cerebral circulation and function. The most common arrhythmias producing syncope or presyncope are profound sinus bradycardia, high-grade atrioventricular (AV) block, supraventricular tachycardia, ventricular tachycardia, pacemaker malfunction, pacemaker induced arrhythmias, and pacemaker syndrome. Arrhythmias can occur as an isolated phenomenon (e.g. Wolff-Parkinson-White syndrome), but are commonly secondary to such disorders as ischaemic heart disease, cardiomyopathy, and valvular hearth disease.
KeywordsAtrial Flutter Ventricular Rate Sick Sinus Syndrome Paroxysmal Supraventricular Tachycardia Temporary Pace
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