The Cardiac Patient & Surgery

Patients with known or suspected cardiac disease undergoing general surgery present a common management problem. Anesthesia and surgery are often associated with marked fluctuations of heart rate and blood pressure, changes in intravascular volume, myocardial ischemia or depression, arrhythmias, decreased oxygenation, increased sympathetic nervous system activity, and alterations in medical regimens and pharmacokinetics. Even with careful monitoring and management, the perioperative period can be very stressful to cardiac patients.

The risk of surgery in patients with heart disease depends primarily on three factors: the type of operation, the nature of the heart disease, and the degree of preoperative stability. The type of anesthesia is less important, though halothane, enflurane, and barbiturates are more severe myocardial depressants, whereas narcotics have little depressive effect. Spinal and epidural anesthesia were previously thought to be preferable in patients with heart disease, but this has not proved to be the case.

The highest-risk procedures are surgery of the aorta and vascular procedures, in part because these patients often have associated severe coronary disease but also because marked blood pressure and volume changes are common.

Major abdominal and thoracic surgery are also associated with substantial cardiovascular risk, especially in older patients with associated cardiovascular disease.

Numerous studies have evaluated the excess risk of surgery in patients with various cardiac diseases. Recent (within 3 months) myocardial infarction, unstable angina, congestive heart failure, and significant aortic stenosis are associated with substantial increases in operative morbidity and mortality rates. Any degree of instability in these conditions magnifies the potential risk. Stable angina, especially in an inactive individual, is also associated with a higher operative risk. Although less common, cyanotic congenital heart disease and severe primary or secondary pulmonary hypertension pose great risks during major surgery. In patients with any of these problems, the risk-to-benefit ratio of the planned surgery should be carefully examined. If the procedure is necessary but elective, consideration should be given to delaying it until full recovery postinfarction and correction or optimal stabilization of the other conditions are achieved. Hypertension should be at least moderately controlled. Patients with severe angina should have increased medical therapy or be considered for revascularization before noncardiac surgery. Symptomatic arrhythmias, nonsustained ventricular Tachycardia, or high-grade atrioventricular block and cardiac failure should be treated optimally.

Clinical assessment provides the most useful guidance in determining the risk of noncardiac surgery. Important indicators of high risk have been discussed above. Patients with known but clinically stable heart disease, such as angina pectoris or prior myocardial infarction, are at intermediate risk, particularly for major operations such as vascular surgery. If a history or symptoms of heart failure are present, assessment of left ventricular function can be very helpful in perioperative management. Although frequently advocated, further noninvasive testing for myocardial ischemia for the purpose of risk stratification is probably overutilized. Tests such as stress myocardial perfusion scintigraphy or dobutamine echocardiography should be reserved for situations in which the results may alter patient management. There is no evidence that prophylactic revascularization by either PTCA or coronary artery bypass surgery alters long-term outcome in patients undergoing noncardiac surgical procedures without the usual indications for PTCA or CABG. Only in the case of major vascular operations is perioperative mortality and morbidity high enough that prophylactic PTCA or CABG should be considered.

However, it should be noted that many patients undergoing surgery have not had recent medical follow-up, and this may be an appropriate opportunity to perform a more complete evaluation. Thus, stress testing may be indicated for selected patients with symptomatic angina or prior myocardial infarction with a view to instituting more comprehensive medical management or performing coronary revascularization to reduce long-term (rather than perioperative) mortality and morbidity. At the least, such patients should not be discharged without a plan for an appropriate follow-up and institution of antihyperlipidemic, aspirin, and ß-blocker therapy as indicated.

Once the decision to operate is made, careful management is essential. Most cardiac medications should be continued preoperatively and postoperatively. In patients judged to be at high risk or medium risk, ß-blockers should be initiated preoperatively unless contraindicated. If practical, oral therapy with atenolol or metoprolol should be started several days prior to surgery and gradually increased to 100 mg in single or divided doses. Otherwise, 15 mg of metoprolol or 10 mg of atenolol may be administered intravenously in 5 mg increments separated by 5-10 minutes prior to induction. These doses should be repeated every 12 hours - or more frequently if excessive Tachycardia occurs - until oral therapy can be commenced. Monitoring is an important prophylactic measure in high-risk individuals; hemodynamic monitoring can facilitate early intervention in patients with heart failure, severe valve disease, or easily induced myocardial ischemia. Excessive hypertension, hypotension, and myocardial ischemia should be identified and appropriately treated using rapidly acting agents. Transesophageal echocardiography can also be used for intraoperative monitoring of ischemia, but its value has never been established in well-designed studies. Ischemic events, whether symptomatic or silent, should be vigorously treated.

Auerbach AD et al: Beta-blockers and reduction of cardiac events in noncardiac surgery: scientific review. JAMA 2002;287:1435. 

Boersma E et al: Predictors of cardiac events after major vascular surgery: role of clinical characteristics, dobutamine echocardiography, and beta-blocker therapy. JAMA 2001;285: 1865.

Eagle KA et al: ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery - executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). J Am Coll Cardiol 2002;39:542.

Fleisher LA et al: Clinical practice. Lowering cardiac risk in non-cardiac surgery. N Engl J Med 2001;345:1677.

RELATED STORIES:
Cardiovascular Screening of Athletes   The Cardiac Patient & Pregnancy   Cardiovascular Complications of Pregnancy   Traumatic Heart Disease   Pulmonary Heart Disease (Cor Pulmonale)   Cardiac Involvement in Miscellaneous Systemic Diseases   Neoplastic Diseases of the Heart   Constrictive Pericarditis   Primary Pulmonary Hypertension   Pericardial Effusion   Acute Pericarditis   Rheumatic Heart Disease

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