Creation of complete atrioventricular block in dogs significantly increased LV mass, RV mass, ejection fraction, and Q-T time within 14-21 days (all P<0.05).
What is the nature and time course of biventricular hypertrophy and electrical/mechanical changes after creation of complete atrioventricular block in adult dogs?
In a canine model of complete AV block, electrophysiological, mechanical, and structural adaptations to bradycardia-induced volume overload develop rapidly and are completed within 3 weeks, with greater hypertrophy observed in the right ventricle.
p-value: p=<0.05
To determine the nature and time course of biventricular hypertrophy and concomitant electrical and mechanical changes after creation of complete atrioventricular block (CAVB), six adult dogs (22-30 kg) were subjected to serial magnetic resonance imaging (MRI) and electrocardiography. After 6 days of CAVB, left ventricular (LV) mass, ejection fraction (EF), and Q-T time at a paced rhythm of 60 beats/min were already significantly increased. Maximal values were reached within 14-21 days of CAVB: LV mass, from 116 +/- 11 to 143 +/- 12 g; right ventricular (RV) mass, from 40 +/- 3 to 55 +/- 6 g; EF, from 68 +/- 6% to 86 +/- 5%; and Q-T time, from 285 +/- 25 to 330 +/- 35 ms, all P < 0.05. Cardiac output returned to baseline at day 14. End-diastolic wall thickness increased only in the RV, in which angiotensin type 1 (AT1) receptor mRNA expression was significantly greater. The autopsy correlated well with the MRI results (r = 0.98, P< or = 0.01). In conclusion, electrophysiological, mechanical, and structural adaptation processes after bradycardia-induced volume overload develop rapidly and are completed within 3 wk. The degree of hypertrophy was greater in the RV, which was associated with an increase in AT1 receptor mRNA.
Verduyn et al. (Fri,) conducted a other in Complete atrioventricular block (n=6). Creation of complete atrioventricular block (CAVB) vs. Baseline (before CAVB) was evaluated on Left ventricular mass, right ventricular mass, ejection fraction, and Q-T time (p=<0.05). Creation of complete atrioventricular block in dogs significantly increased LV mass, RV mass, ejection fraction, and Q-T time within 14-21 days (all P<0.05).