Despite the widespread use of amiodarone in non-surgical patients, its role in the management of supraventricular tachyarrhythmias after cardiac surgery is not clear. We set out to compare the relative efficacy of amiodarone and digoxin in the management of atrial fibrillation and flutter in the early postoperative period. This prospective randomised trial comprised 30 patients, previously in sinus rhythm, who developed sustained atrial fibrillation or flutter following myocardial revascularisation, valve surgery or combined procedures. Amiodarone was administered as an intravenous loading dose followed by a continuous infusion. Digoxin was given as an intravenous loading dose followed by oral maintenance therapy. Electrocardiographic and haemodynamic monitoring was continued for 24 h after the commencement of treatment. There was a marked reduction in heart rate in both groups, mainly in the first 6 h, from 146 to 89 beats per minute in the amiodarone group and from 144 to 95 in the digoxin group. At the end of the 24 h, one of the 15 patients in the amiodarone group and 3 of the 15 patients in the digoxin group remained in atrial fibrillation. No patient in either group developed adverse reactions. We conclude that intravenous amiodarone therapy is safe and at least as effective as digoxin in the initial management of arrhythmias after cardiac surgery.

ObjectiveTo determine the results of cardiac surgery in the very elderly. Design and subjectsA retrospective study of 56 very elderly patients (mean age 82 years, range 79‐89 years) undergoing open heart surgery between 1988 and 1991. Thirty‐three patients had coronary artery bypass grafting, 12 had valve replacement alone and 11 had valve replacement with an associated procedure. SettingSt Francis Xavier Cabrini Hospital, Melbourne — a large private hospital. ResultsThere were four in‐hospital deaths (7%). The one‐year actuarial survival rate was 88%. Of the 49 survivors, 92% were in New York Heart Association (NYHA) Class III or IV before operation, whereas 96% were in NYHA Class I or II a mean of 15 months after operation. ConclusionIn very elderly patients with medically refractory cardiac symptoms, cardiac surgery has a tolerable mortality and provides excellent relief of symptoms.

No abstract

Myocardial pH reflects the metabolic status of the heart and pH monitoring is an invaluable way to monitor the efficacy of myocardial protection during cardiac surgery. We developed a miniature antimony electrode for pH measurement in the heart. We examined the sensitivity, accuracy and the effects of temperature and oxygen tension on pH readings with this electrode in standard buffers and in anaesthetized dogs. In buffers the antimony electrode exhibited a gradient of -50.3 +/- 1.8 mV pH-1 at 25 degrees C, close to the Nernstian slope and showed a high correlation with conventional glass electrode readings (mean difference 0.027 +/- 0.0035 pH, r2 = 0.97). With increasing temperature the antimony electrode pH readings increased by 0.03 +/- 0.002 pH degree C(-1). With increasing PO2 the pH reading decreased (-0.73 pH/log PO2 mm Hg, r2 = 0.96). In the dog heart the antimony electrode showed a decrease in myocardial pH with increasing PCO2, and an increase in pH when NaHCO3 was given intravenously. Coronary occlusion resulted in paradoxically higher pH readings with the antimony electrode due to the effect of lowered myocardial PO2 interfering with pH measurement. The dissolution of antimony from the electrode in blood plasma was tested and found to be low. These studies suggest that antimony electrodes have low toxicity and provide accurate pH determinations under conditions of constant PO2. For more widespread clinical application, the problem of oxygen interference needs to be solved.

There have been many studies of reperfusion injury after normothermic ischemia. However, there have been few clinically relevant studies on the nature and time course of recovery of the myocardium during reperfusion after hypothermic cardioplegia. We studied reperfusion in the isolated dog heart supported by another dog. After 2 h of cardioplegic arrest at 20 degrees C, 11 normal hearts were reperfused for 30 min at optimal coronary pressures (60-100 mm Hg mean). The following events occurred: rapid rewarming, a transient hyperemia followed by a rapid return of both coronary blood flow and myocardial oxygen consumption to normal, washout of lactate, recovery of contractility and a slight decline in ATP. Most of these events occurred during the first 15 min of reperfusion. We concluded that, in normal hearts which are well protected during hypothermic cardioplegia, reperfusion at optimal coronary pressure results in recovery of the myocardium within 15 min, with the exception of recovery of ATP levels.