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Pathophysiology Bundle branch reentrant (BBR) ventricular tachycardia (VT) is a reentrant VT with a well-defined macroreentry circuit, incorporating the right bundle branch (RB) and left bundle branch (LB) as obligatory limbs of the circuit, connected proximally by the His bundle…
Pathophysiology Cardiomyopathies are traditionally defined on the basis of structural and functional phenotypes, notably dilated, hypertrophic, restrictive, and arrhythmogenic. Dilated cardiomyopathy (DCM) is characterized by ventricular dilatation and systolic dysfunction in the absence of known abnormal loading conditions or significant…
Pathophysiology The His-Purkinje system plays an important role in the genesis of cardiac arrhythmias. The mechanism of several types of monomorphic ventricular tachycardias (VTs) has been directly linked to the Purkinje system, including bundle branch reentrant VT, interfascicular reentrant VT,…
Pathophysiology Ventricular tachycardia (VT) is usually associated with structural heart disease, most commonly coronary artery disease and cardiomyopathy. However, about 10% of patients who present with VT have no obvious structural heart disease (idiopathic VT). Absence of structural heart disease…
Classification of ventricular tachyarrhythmias Ventricular tachycardia (VT) is defined as a tachycardia (rate >100 beats/min) with three or more consecutive beats that originates below the bifurcation of the His bundle (HB), in the specialized conduction system, the ventricular muscle, or…
Clinical considerations Causes of wide complex tachycardias A narrow QRS complex (120 milliseconds or less) requires rapid, highly synchronous electrical activation of the right and left ventricles, which can only be achieved through the specialized, rapidly conducting His-Purkinje system (HPS).…
A “supraventricular” origin of a tachycardia implies the obligatory involvement of one or more cardiac structures above the bifurcation of the His bundle (HB), including atrial myocardium, atrioventricular node (AVN), proximal HB, coronary sinus (CS), pulmonary veins, venae cavae, or…
A working definition of an atypical bypass tract (BT) is a conduction pathway that bypasses all or part of the normal conduction system but is not a rapidly conducting pathway connecting atrium and ventricle near the mitral or tricuspid annulus.…
Types of bypass tracts Bypass tracts (BTs) are remnants of the atrioventricular (AV) connections caused by incomplete embryological development of the AV annuli and failure of the fibrous separation between the atria and ventricles. There are several types of BTs,…