Ventricular tachyarrhythmias following surgery for myocardial revascularization. A follow-up study

Perioperative Cardiac Issues: Postoperative Arrhythmias

This article reviews current concepts about the diagnosis and acute management of postoperative arrhythmias. A systematic approach to diagnosis of arrhythmias and evaluation of predisposing factors is presented, followed by consideration of common bradyarrhythmias and tachyarrhythmias in the postoperative setting. Postoperative arrhythmias are common and represent a major source of morbidity after surgical procedures, both cardiac and noncardiac. Postoperative dysrhythmias are most likely to occur in patients with structural heart disease. The initiating factor for an arrhythmia following surgery is usually a transient insult such as hypoxemia, cardiac ischemia, catecholamine excess, or electrolyte abnormality. Management includes correction of these imbalances and, if clinically indicated, medical therapy directed at the arrhythmia itself.

New treatments for perioperative cardiac arrhythmias

Cardiac arrhythmias remain a major source of morbidity, mortality, and prolonged postoperative hospital stay in surgical patients. Recent studies in patients experiencing out-of-hospital cardiac arrest have expanded our knowledge in the management of cardiac arrhythmias. Future advances require additional studies focused on the unique proarrhythmic substrates in surgical patients, to provide a clear rationale for antiarrhythmic drug therapy in the perioperative period.

Noncardiac surgery: postoperative arrhythmias

Postoperative arrhythmias are common and represent a major source of morbidity after both cardiac and noncardiac surgical procedures. Postoperative dysrhythmias are most likely to occur in patients with structural heart disease. The initiating factor for an arrhythmia in a given patient after surgery is usually a transient insult, such as hypoxemia, cardiac ischemia, catecholamine excess, or electrolyte abnormality. Management includes correction of these imbalances and medical therapy directed at the arrhythmia itself. The physiologic impact of arrhythmias depends on arrhythmia duration, ventricular response rate, and underlying cardiac function. Similarly, urgency and type of treatment is determined by the physiologic impact of the arrhythmia, as well as by underlying clinical status. The purpose of this review is to provide current concepts of diagnosis and acute management of arrhythmias after noncardiac surgery. A systematic approach to arrhythmia diagnosis and evaluation of predisposing factors is presented, followed by consideration of specific bradyarrhythmias and tachyarrhythmias in the postoperative setting.

Prognosis of patients with frequent premature ventricular complexes and nonsustained ventricular tachycardia after coronary artery bypass graft surgery

BACKGROUND

Previous studies in small groups of predominantly nongeriatric patients showed that complex ventricular arrhythmias occurring after coronary artery graft (CABG) surgery are of no prognostic significance. The purpose of this study was to compare the prognosis of patients with and without advanced grade ventricular arrhythmias (AGVA) after CABG in a large group of patients. [In this paper, AGVA is used as an abridged definition of frequent premature ventricular complexes (PVCs) and nonsustained ventricular tachycardia (NSVT) which represent advanced grade ventricular arrhythmias.]

METHODS

Twenty-four hour ambulatory electrocardiographic (ECG) monitoring was performed 3 days after CABG in 185 consecutive patients with 185 closely matched control patients without AGVA. Of 185 patients with AGVA, 77 had frequent PVCs, 45 had NSVT, and 63 patients had both. The average age of both groups was 65 +/ 9.7 years. Patients were followed for 34 +/ 10 months, and in 30 patients ambulatory monitoring was repeated at the end of the follow-up.

RESULTS

Fifteen AGVA and nine control patients died. In each group seven deaths were noncardiac. Six nonsudden and two sudden cardiac deaths (SCD) occurred in the AGVA group at 2-36 months after CABG and two nonsudden cardiac deaths in the control group at 3 and 35 months after CABG (p = 0.053). Both SCDs occurred 33 months after CABG after new events known to predispose to SCD. In 18 of 30 patients AGVA was no longer present when ambulatory ECG monitoring was repeated 36 +/ 11 months after CABG.

CONCLUSION

AGVA after CABG was not a marker of an early sudden cardiac death. In 60% of patients not treated with antiarrhythmic drugs, AGVA was no longer present late after operation.

Incidence and prevention of supraventricular tachyarrhythmias after coronary bypass surgery

Supraventricular tachyarrhythmias are a frequent complication encountered after coronary artery bypass grafting. A retrospective survey of 102 consecutive patients undergoing exclusive bypass grafting at St. Mary's Hospital supplemented by a review of 16 published reports over a period of 10 years revealed a mean incidence of post-operative tachyarrhythmia of 33.4% in 1344 patients (range 11.4-100%). One hundred and thirty two patients undergoing exclusive bypass surgery, were randomised prospectively in double blind fashion to receive either oral timolol or matched placebo approximately 24 hours after surgery. In the 66 patients receiving timolol, there was a significant reduction of post-operative arrhythmias compared to the 66 patients receiving placebo: from 19.7 to 7.5% (P less than 0.05). Of all arrhythmias, two thirds appeared under 48 hours after surgery. In the timolol group, 4 patients developed systemic hypotension. This was readily reversed by withdrawing the drug. No other side effects were noted. The use of oral timolol after coronary artery surgery significantly lowers the incidence of post-operative supraventricular arrhythmias.

beta-Blockade therapy for supraventricular tachyarrhythmias after coronary surgery: a propranolol withdrawal syndrome?

A high incidence of cardiac arrhythmias and hypertension has been noted after coronary artery bypass surgery in patients previously treated with oral propranolol. Forty-two patients undergoing coronary bypass surgery had propranolol withdrawal 10 hours before surgery and were randomized into a group treated with propranolol immediately postoperatively, and a nontreatment group. Patients treated with prophylactic propranolol had a significantly lower incidence of postoperative supraventricular arrhythmias compared to patints who received no prophylaxis. All the arrhythmias responded rapidly to 1 mg of intravenous propranolol therapy, whether it was used as a primary treatment or as a supplement to prophylactic propranolol. The findings suggest that (1) there is a high incidence of supraventricular arrhythmias and sinus tachycardia after coronary artery bypass which might reflect an abrupt propranolol withdrawal, and (2) that perioperative prophylactic or supplementary propranolol therapy will successfully prevent or treat most of these arrhythmias.