Chapter 44

1. Patients with preoperative blood pressure elevation have exaggerated perioperative blood pressure fluctuations, which may be associated with electrocardiogram (ECG) evidence of myocardial ischemia. The American College of Cardiology/American Heart Association (ACC/AHA) Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery recommend that antihypertensive medication be continued during the perioperative period. Particular care should be taken to avoid withdrawal of β-blockers and clonidine because of the potential for withdrawal syndromes.

2. Recommendations for patients taking diuretics call for withholding diuretics on the day of surgery unless evidence suggests volume overload or signs and symptoms of overt congestive heart failure (CHF). In stable patients with chronic mild-to-moderate hypokalemia without signs or symptoms of hypokalemia (eg, muscle weakness, ileus, and nephropathy) and in the absence of dysrhythmias or digitalis use, anesthesia and surgery can proceed.

3. α2-Agonists have many desirable effects, such as minimum alveolar concentration (MAC) reduction, analgesia, anxiolysis, sedation, and sympatholysis. Recent studies evaluating the perioperative effect of α2-agonists during noncardiac surgery show less perioperative myocardial ischemia. The ACC/AHA guidelines introduced the use of α2-agonists as a class IIb recommendation for perioperative control of hypertension or risk reduction in patients with known coronary artery disease (CAD) or major risk factors for CAD.

4. During the perioperative period, patients maintained on angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers through the morning of the surgery have an increased number of hypotensive episodes requiring treatment with vasopressors.

5. Perioperatively, intravenous (IV) nitroglycerin may be used for treatment of myocardial ischemia, CHF, acute volume overload, systemic and pulmonary hypertension, and coronary artery spasm. It enhances blood flow to the subendocardium and areas of ischemia by both decreasing preload and left ventricular end-diastolic pressure and volume.

6. The recent focus on perioperative β-blockade has led to mounting evidence that their prophylactic use will reduce cardiac mortality and morbidity. β-Blockers reduce ischemia by decreasing myocardial oxygen demand caused by increased stress and catecholamine release in the perioperative period. However, their aggressive prophylactic use without proper titration may result in an increased incidence of hypotension, stroke, and mortality. The ACC/AHA guidelines state that β-blockers should be titrated to effect preferably days to weeks before elective surgery in patients at risk for or with evidence of ischemia.

7. The calcium channel blockers represent a diverse group of compounds with dissimilar structures and pharmacologic effects. Unlike β-blockers, which all depend on blockade of receptors for their activity, the sites and mechanisms of action of the individual calcium channel blockers vary, as do their individual actions on different tissues.

8. Over the past decade, the use of most antidysrhythmic drugs has been reassessed and dramatically limited as a result of increased awareness of their proarrhythmic potential and advances in ablation techniques. Moreover, recent clinical trials have demonstrated negative effects on survival in many situations when these drugs may have been administered in the past. Finally, implantable cardiodefibrillators have largely replaced antidysrhythmic medications in the management of ventricular dysrhythmias.

9. Amiodarone is considered by some the most ...

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