BACKGROUND: Bidirectional ventricular tachycardia (BVT), which is characterized by an alternating beat-to-beat ECG QRS axis, is a rare but intriguing arrhythmia associated with digitalis toxicity, familial catecholaminergic polymorphic ventricular tachycardia (CPVT), and several other conditions that predispose cardiac myocytes to delayed afterdepolarizations (DADs) and triggered activity. Evidence from human and animal studies attributes BVT to alternating ectopic foci originating from the distal His-Purkinje system in the left and/or right ventricle, respectively. OBJECTIVE: The purpose of this study was to evaluate a simple "ping pong" model of reciprocating bigeminy to explain BVT. METHODS: We constructed a two-dimensional anatomic model of the rabbit ventricles with a simplified His-Purkinje system, in which different sites in the His-Purkinje system had different heart rate thresholds for DAD-induced bigeminy. RESULTS: When the heart rate exceeded the threshold for bigeminy at the first site in the His-Purkinje system, ventricular bigeminy developed, causing the heart rate to accelerate and exceed the threshold for bigeminy at the second site. Thus, the triggered beat from the first site induced a triggered beat from the second site. The triggered beat from the second site next reciprocated by inducing a triggered beat from the first site, and so forth. Bigeminy from two sites produced BVT, and that from three or more sites produced polymorphic VT. CONCLUSION: This "ping pong" mechanism of reciprocating bigeminy readily produces the characteristic ECG pattern of BVT and its degeneration to polymorphic VT if additional sites develop bigeminy.
BACKGROUND: Bidirectional ventricular tachycardia (BVT), which is characterized by an alternating beat-to-beat ECG QRS axis, is a rare but intriguing arrhythmia associated with digitalis toxicity, familial catecholaminergic polymorphic ventricular tachycardia (CPVT), and several other conditions that predispose cardiac myocytes to delayed afterdepolarizations (DADs) and triggered activity. Evidence from human and animal studies attributes BVT to alternating ectopic foci originating from the distal His-Purkinje system in the left and/or right ventricle, respectively. OBJECTIVE: The purpose of this study was to evaluate a simple "ping pong" model of reciprocating bigeminy to explain BVT. METHODS: We constructed a two-dimensional anatomic model of the rabbit ventricles with a simplified His-Purkinje system, in which different sites in the His-Purkinje system had different heart rate thresholds for DAD-induced bigeminy. RESULTS: When the heart rate exceeded the threshold for bigeminy at the first site in the His-Purkinje system, ventricular bigeminy developed, causing the heart rate to accelerate and exceed the threshold for bigeminy at the second site. Thus, the triggered beat from the first site induced a triggered beat from the second site. The triggered beat from the second site next reciprocated by inducing a triggered beat from the first site, and so forth. Bigeminy from two sites produced BVT, and that from three or more sites produced polymorphic VT. CONCLUSION: This "ping pong" mechanism of reciprocating bigeminy readily produces the characteristic ECG pattern of BVT and its degeneration to polymorphic VT if additional sites develop bigeminy.
Authors: Ali Baher; Zhilin Qu; Ashkan Hayatdavoudi; Scott T Lamp; Ming-Jim Yang; Fagen Xie; Stephen Turner; Alan Garfinkel; James N Weiss Journal: Am J Physiol Heart Circ Physiol Date: 2006-08-04 Impact factor: 4.733
Authors: Björn C Knollmann; Nagesh Chopra; Thinn Hlaing; Brandy Akin; Tao Yang; Kristen Ettensohn; Barbara E C Knollmann; Kenneth D Horton; Neil J Weissman; Izabela Holinstat; Wei Zhang; Dan M Roden; Larry R Jones; Clara Franzini-Armstrong; Karl Pfeifer Journal: J Clin Invest Date: 2006-08-24 Impact factor: 14.808
Authors: Jan E Azarov; Dmitry N Shmakov; Vladimir A Vityazev; Irina M Roshchevskaya; Mikhail P Roshchevsky Journal: Comp Biochem Physiol A Mol Integr Physiol Date: 2006-11-10 Impact factor: 2.320
Authors: Marina Cerrone; Sami F Noujaim; Elena G Tolkacheva; Arkadzi Talkachou; Ryan O'Connell; Omer Berenfeld; Justus Anumonwo; Sandeep V Pandit; Karen Vikstrom; Carlo Napolitano; Silvia G Priori; José Jalife Journal: Circ Res Date: 2007-09-13 Impact factor: 17.367