Effects of acute gastric distention and recovery on tendency for ventricular arrhythmia in dogs

The gastric distention-volvulus (GDV syndrome occurs commonly in large-bree d dogs and may prove fatal in 15-68% of cases. Approximately 43% of cases w ith gastric distention (GD) or volvulus develop cardiac arrhythmias that ca n contribute to mortality. Most of these arrhythmias are ventricular in ori gin and ventricular fibrillation (VF) may be the cause of death. This study used an iatrogenic model of acute GD to investigate the prevalence of vent ricular arrhythmias during acute GD and its recovery, ii programmed electri cal stimulation (PES) may uncover tendency to VF, if the Q-T interval corre cted for heart rate (Q-Tc) of the electrocardiogram (ECG predicts tendency to VE and if hemodynamic changes predate VE Eleven beagles, anesthetized wi th morphine and alpha-chloralose, and instrumented so that vascular pressur es, cardiac output, and PES could be recorded, were used. Five were unpertu rbed. whereas acute GD to a pressure of 30 mm Hg far 1.5 hours was produced in 6 others. The results were as follows. No dogs with GD developed sponta neously occurring arrhythmias. VF was produced in no dogs by conventional P ES, but occurred in all dogs (P <.05) with GD and none of the controls, usi ng accelerated ventricular pacing. The Q-Tc interval of the ECG prolonged m inimally in dogs with GD, and shortened (P <.05) in controls. Some hemodyna mic changes did predate VE In conclusion dogs with acute GD have a tendency for VE which may be uncovered by accelerated PES. The mechanism for the vu lnerability to arrhythmia with GD is unknown.