Harry A. Wellons

Mitral repair is superior to replacement when associated with coronary artery disease.

Objective:To compare the outcomes of mitral repair and replacement in revascularized patients with ischemic mitral regurgitation. Summary Background Data:Combined coronary bypass (CABG) and mitral procedures have been associated with the highest mortality (>10%) in cardiac surgery. Recent studies have suggested that mitral valve replacement (MVR) with sparing of the subvalvular apparatus had comparable results to mitral repair when associated with CABG. Methods:Over the past 7 years, 54 patients had CABG/mitral repair versus 56 who had CABG/MVR with preservation of the subvalvular apparatus. The groups were similar in age at 69.2 years in the replacement group versus 67.0 in the repair group. We compared these 2 groups based on hospital mortality, incidence of complications including nosocomial infection, neurologic decompensation (stroke), pulmonary complication (pneumonia, atelectasis, and prolonged ventilation), and renal complications (acute renal failure or insufficiency). Results:The mitral repair group had a hospital mortality of 1.9% versus 10.7% in the replacement group (P = 0.05). Infection occurred in 9% of repairs compared with 13% of replacements (P = 0.59). The incidence of stroke was no different between groups (2 of 54 repairs vs. 2 of 56 replacements, P = 1.00). Pulmonary complication rate was 39% in repairs versus 32% in replacements (P = 0.59). Worsening renal function occurred in 15% of repairs versus 18% of replacements (P = 0.67). Conclusions:Mitral repair is superior to mitral replacement when associated with coronary artery disease in terms of perioperative morbidity and hospital mortality. Although preservation of the subvalvular apparatus with MVR has a theoretical advantage in terms of ventricular function, mitral repair clearly adds a survival benefit in patients with concomitant ischemic cardiac disease.

Unanticipated Postoperative Ventricular Tachyarrhythmias

Eighteen (1.4%) of 1,251 patients who underwent cardiac operations during a three-year period had new sustained ventricular tachycardia (12 patients) or ventricular fibrillation (6 patients) not caused by but resulting in hemodynamic compromise. In 13 patients, the initial arrhythmia occurred in the first 48 hours postoperatively. Lidocaine was being administered to 10 of these patients for suppression of previously noted ventricular ectopy, but it did not prevent the occurrence of the arrhythmia. The initial episode was fatal for 5 patients. Two of these deaths were directly related to the adverse effects of the antiarrhythmic agents used to suppress ventricular tachycardia or fibrillation. Five of 10 survivors underwent electrophysiological studies after initial resuscitation. In all 5, programmed ventricular stimulation reproduced the clinical arrhythmia. There have been 2 late sudden deaths in patients who either did not undergo or remained uncontrolled at electrophysiological study during serial drug trials. Our experience suggests that a cardiac operation may unmask or induce potentially lethal arrhythmias that previously had not been apparent. Pharmacological suppression of ventricular ectopy does not necessarily prevent ventricular tachycardia or ventricular fibrillation in the early postoperative period. Electrophysiological study may be helpful in determining the appropriate prophylactic therapy in such patients.

Determinants of reperfusion cardiac electrical activity after cold cardioplegic arrest during coronary bypass surgery

In a prospective study of 99 patients with coronary artery disease, reperfusion of the heart after a period of ischemia (protected by contemporary techniques of myocardial preservation) resulted in spontaneous resumption of cardiac electrical activity in 53%, spontaneous defibrillation in 10%, reperfusion ventricular fibrillation (VF) in 32% and indeterminate rhythm in 5%. In hearts spontaneously developing rhythms excluding VF (as opposed to hearts requiring direct-current shock), factors significantly associated were a higher plasma potassium concentration (5.2 vs 4.8 mEq/liter), shorter reperfusion time (1 vs 4 minutes), higher plasma magnesium concentration (1.36 vs 1.25 mg/dl) and a lower myocardial temperature (27 vs 32 degrees C). The duration of ischemia, arterial blood gas levels, plasma catecholamine levels, plasma ionized calcium levels, volume of cardioplegia and mean arterial pressure did not relate to occurrence of spontaneous episodes. However, VF developed in 39 of 52 patients (75%) with spontaneous resumption of electrical activity. This event was associated with lower myocardial temperature. Thus, direct-current shocks were ultimately required in 77 of the 99 patients (78%). Although certain thermal, biochemical and hemodynamic variables facilitate spontaneous resumption of cardiac rhythm, the development of VF may negate the potential benefit of this event in the prevention of myocardial damage from direct-current defibrillation.

Acute dissecting aortic aneurysm resulting from retrograde brachial arterial catheterization. Successful operative intervention.

Abstract A case of type I aortic dissection occurring as a complication of retrograde catheterization of the right brachial artery is described. The problem was immediately identified and, after appropriate studies were performed, operative intervention was successfully carried out. Although this lesion is an extremely rare complication of the catheterization procedure, the possibility of its occurrence must be kept in mind. Prompt recognition, accurate diagnostic evaluation and immediate operation can result in a successful outcome.

Low-energy defibrillation: Safe and effective

During cardiopulmonary bypass, 150 cardiac surgical patients were prospectively evaluated for the number, energy, current, and success rates of direct current (DC) shocks required to terminate reperfusion ventricular fibrillation (1 degree) or ventricular fibrillation occurring subsequent to a nonfibrillatory reperfusion rhythm (2 degrees). Thirty-one percent of 1-J shocks and 58% of 2.5-J shocks defibrillated. Above 2.5 J, the defibrillation success rate reached a plateau of 50-60%. Myocardial resistance decreased significantly after the first shock but remained stable during subsequent shocks. Lower defibrillating currents and myocardial resistances than had been previously reported were observed. The feasibility of low-energy defibrillation during cardiopulmonary bypass was therefore documented.