The crista terminalis thickness might have the capacity to block conduction, as well as the low voltage of the CTI, can be signs of arrhythmogenesis and poor conduction in the right atrium.Ītypical atrial flutter or other macroreentrant atrial tachycardia has a circuit configuration different from the typical right atrial flutter circuit. The reason behind the existence of the circuit might relate to the nature of the anatomical structures that are circumscribing the circuit.
The absence of an isoelectric line between P waves or QRS complexes is due to the constant cycling of the circuit or atrial activation. Commonly the atrioventricular conduction will be 2 to 1 with an atrial rate of 300 beats per minute with a ventricular rate of 150 beats per minute, but this can be variable depending on the underlying parasympathetic stimulus or refractoriness of the atrioventricular node. Īs this cycle occurs in the atrium, conduction is determined by the atrioventricular node mechanism to conduct the atrial impulse. The mechanism of arrhythmia is a macro-reentry activation of the right atrium from the interatrial septum and along the crista terminalis with passive activation of the left atrium via the coronary sinus muscular connection. The crista terminalis is a functional barrier that induces a transverse conduction block, steep slope, and arborization that allows the circuit to exist. With aging and atrial dilation, occurs fibrosis of the atrial tissue and produce non-uniform anisotropic conduction through the CTI. The mechanism of slow conduction is not well understood but might be related to anisotropic fiber orientation. The CTI provides the slow conduction pathway, and it presents in the lateral aspect of the younger patient and the medial aspect in the older patients. These structures are essential to provide the pathway length for the flutter system. The Todaro tendon, crista terminalis, the inferior vena cava, the tricuspid valve annulus, and the coronary sinus os delineate the circuit. Typical atrial flutter is the most common type of atrial flutter and is a macroreentrant atrial tachycardia that uses the CTI as an essential part of the circuit. Less commonly, atrial activation can be in a clockwise fashion, and thus electrocardiographic appearance is different, one is unable to differentiate it easily from not isthmus-dependent atrial flutter. The atypical atrial flutter is independent of the CTI, and the origin of the arrhythmia can be in the right atrium or the left atrium. Typical atrial flutter is seen in the electrocardiogram as continuous negative modulation in inferior leads (II, III, and AVF) and flat atrial deflections in leads I and aVL this is due to the way of propagation and activation of the macro-reentrant circuit as will be described in the pathophysiology section.
Typical or cavotricuspid isthmus (CTI) dependent is the most common type of atrial flutter this rhythm originates in the right atrium at the level of the tricuspid valve annulus. Electrical axis of the flutter waves can help to determine the origin of the atrial flutter. Electrocardiographic findings of atrial flutter are flutter waves without an isoelectric line in between QRS complex. Ītrial flutter is a macro-reentrant tachycardia and depending on the site of origin can be typical or atypical atrial flutter. In this review will summarize the management of atrial flutter.Ītrial flutter is one of the most common arrhythmias and is characterized by an abnormal cardiac rhythm that is fast with an atrial rate of 300beats/min and a ventricular rate that can be fixed or be variable that can cause palpitations, fatigue, syncope, and embolic phenomenon. Atrial fibrillation and atrial flutter are the most common of these atrial arrhythmias, and the other less common supraventricular arrhythmias are atrial tachycardias, atrioventricular reentrant tachycardia, atrioventricular nodal tachycardia, and others. Supraventricular arrhythmias are a diverse group of atrial arrhythmias.
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