Heterogeneity of left ventricular signal characteristics in response to acute vagal stimulation during ventricular fibrillation in dogs

• Published in: Texas Heart Institute journal 2011, Vol.38 (6), p.621-626
• Main Authors: Nazeri, Alireza, Elayda, MacArthur A, Dragnev, Lubomir, Frank, Christopher M, Qu, Jihong, Afonso, Valtino X, Rasekh, Abdi, Saeed, Mohammad, Cheng, Jie, Shuraih, Mossaab, Massumi, Ali, Razavi, Mehdi
• Format: Article
• Language: English
• Subjects: Animals; Cardiac Pacing, Artificial; Disease Models, Animal; Dogs; Electrophysiologic Techniques, Cardiac; Fourier Analysis; Heart Conduction System - physiopathology; Laboratory Investigation; Time Factors; Vagus Nerve Stimulation; Ventricular Fibrillation - etiology; Ventricular Fibrillation - physiopathology; Ventricular Fibrillation - therapy; Ventricular Function, Left
• ISSN: 0730-2347; 1526-6702

Studies have shown that long-term vagal stimulation is protective against ventricular fibrillation; however, the effects of acute vagal stimulation during ventricular fibrillation in the normal heart have not been investigated. We examined the effects of acute vagal stimulation on ventricular fibrillation in a canine model. In 4 dogs, we induced 30-second periods of ventricular fibrillation by means of intraventricular pacing. During 2 of the 4 periods of fibrillation that we analyzed, vagal stimulation was delivered through electrodes in the caudal ends of the vagus nerves. Noncontact unipolar electrograms were recorded from 3 ventricular regions: the basal septum, apical septum, and lateral free wall. We then computed the most frequent cycle length, mean organization index, and mean electrogram amplitude for each region. During fibrillation, vagal stimulation shortened the most frequent cycle lengths in the basal septum (P=0.02) and apical septum (P=0.0001), but not in the lateral wall (P=0.46). In addition, vagal stimulation significantly reduced the mean organization indices in the apical septum (P