2016 ACVIM Forum Research Abstract Program

The results of our study indicate that cats that developed pleural effusion had significantly more right atrial enlargement in addition to left atrial enlargement than cats that developed only pulmonary edema. No echocardiographic evidence of pulmonary hypertension was found in any of the four groups of cats. The potential causes for right atrial enlargement in the cats with pleural effusion include concurrent right-sided cardiac disease or pulmonary hypertension that was not detected by these echocardiographic parameters. Additional studies determining the degree of RA enlargement associated with the development of pleural effusion could be useful in predicting CHF manifestation in cats with cardiomyopathy. In human, post-operative dysrhythmia is an important complication after cardiac surgery, a major cause of increasing mortality and lengthening hospitalization. In veterinary field, however, there is little knowledge on rhythmic disturbances complicated by cardiac surgery. The aim of this study is to characterize post-operative arrhythmias and to determine peri-operative predisposing factors to arrhythmias in dogs with open-heart surgery under cardiopulmonary bypass (CPB). This is a prospective and observational study of 70 consecutive dogs undergoing mitral valve repair surgery. The incidence and the types of post-operative arrhythmias were determined by continuously monitoring electrocardiogram for the first 7 days during hospitalization. Occasional premature atrial or ventricular beats were considered insignificant. Serologic and blood-gas parameters measured at serial time points during CPB were normalized and compared between two groups with non-arrhythmic and arrhythmic episodes. All patients showed normal sinus rhythm before surgery. 32 patients (45.7%) had a total of 55 episodes of arrhythmia after cardiac surgery, where ventricular arrhythmias were the most frequently identified (26 of 55; 47.3%). Supraventricular, nodal arrhythmias and conduction blocks accounted for 23.6%, 14.5% and 14.5%, respectively. 53.2% of patients with arrhythmic episodes were recovered to normal sinus rhythm within the first 2 days after surgery. Patients with persistent arrhythmia until discharge were 18.8% (6 of 32). There was no case that permanent pacemaker should be implanted. Although intravenous bolus injection of lidocaine (2 mg/kg) was applied to 2 dogs with polymorphic ventricular tachycardia lasted until 7 days, no improvement was found. No hospital deaths were caused by post-operative arrhythmias (deaths in hospital; 1 respiratory failure, 2 embolic events). Furthermore, the arrhythmic group showed longer duration of CPB (107.2 AE 33.6 minutes, P < 0.05) and aortic cross-clamping time (59.9 AE 13.3 minutes, P < 0.01), and lower glucose level normalized by CPB duration (82.6 AE 38.9 mg/dL/CPB time, P < 0.01), compared to the non-arrhythmic group (CPB time, 90.3 AE 25.7 minutes; cross-clamping time, 50.1 AE 20.6 minutes; normalized glucose level, 126.8 AE 66.7 mg/dL/CPB time). Also, logistic regression model for the probability of post-operative arrhythmias revealed significant effects of the aortic cross-clamping time and the normalized glucose level (adjusted R 2 =0.30, P < 0.001).