We now think that was because in the normal canine heart, the normal atrial substrate failed to develop a line of block between the superior and inferior vena cava which seems necessary for the development of stable atrial flutter. ![]() But Lewis had great difficulty inducing atrial flutter in the model. From these studies, Lewis and colleagues concluded that atrial flutter was due to reentry around their great veins. Their experimental studies included mapping (quite limited) of induced atrial flutter in normal canine atria ( Fig. On the basis of studies in experimental animals and on vector analysis of electrocardiograms in humans, Lewis and colleagues concluded that atrial flutter was the result of circus movement in the atria. 2 The mechanism of classical atrial flutter-the importance of block between the venae cavae Critical to the latter consideration is the increasing recognition that atrial flutter may be due to macroreentrant circuits which are different than that responsible for typical and reverse typical atrial flutter. If it is critically short, it will create fibrillatory conduction and clinical atrial fibrillation if it is sufficiently long, it will result in 1:1 activation of the atria by the reentrant circuit, with resulting clinical atrial flutter. the cycle length of a stable atrial reentrant circuit which develops. We shall also develop the theme that another of the fundamental features that determine whether the atrial tachyarrhythmia becomes atrial flutter or atrial fibrillation often will be the atrial flutter cycle length, i.e. We shall develop the theme that one of the fundamental features that determines whether an atrial tachyarrhythmia becomes sustained atrial flutter or atrial fibrillation is the development of the line of block between the venae cavae. Critical to the development and maintenance of this reentrant circuit are the lateral boundaries, one being fixed (anatomic), the tricuspid valve annulus, and the other almost always being functional, a line of block between the venae cavae. Are these clinical associations mere coincidences, or do they reflect an important underlying similar pathophysiology and even similar mechanism(s)? Data derived largely from a series of unconnected studies in animal models and patients seemingly point to a clear interrelationship between the two, suggesting, if not indicating, that they are two sides of a coin.Ĭlassical atrial flutter, now called typical and reverse typical atrial flutter, is well recognized to be due to a macro-reentrant mechanism, in which the reentrant wave front travels up the inter-atrial septum and down the right atrial free wall or vice versa, respectively. And some antiarrhythmic agents, notably class IC drugs, IA drugs and amiodarone, used to suppress atrial fibrillation not uncommonly ‘convert’ recurrences of atrial tachyarrhythmia to atrial flutter. Both are very common as a temporary atrial tachyarrhythmia shortly after open heart surgery, and often in the same patient. ![]() Patients who primarily manifest atrial flutter commonly also experience atrial fibrillation and vice versa. There has been a long recognized clinical interrelationship between atrial flutter and atrial fibrillation. Arrhythmia (mechanisms), Conduction (block), Impulse formation, Mapping, Supraventricular arrhythmia
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