Avoid extreme or prolonged changes in both heart rate and blood pressure [Slogoff et. al. Anesthesiology 68: 676, 1988]. The traditional recommendation is to maintain SBP within 20% of awake values. That said, ~ 50% of perioperative ischemic episodes are not preceded by premonitory changes in heart rate or blood pressure, thus justifying the use of intraoperative EKG. A 1 mm ST change (elevation or depression) lasting 60 seconds or more increases the risk of a cardiac event by 10-fold, and the risk of death by 2-fold [Mangano et. al. NEJM 323: 1781, 1990], and a 5 minute episode of tachycardia (HR > 105) can increase the risk of death 10-fold if it occurs in the post-operative period
Induction and Intubation
Etomidate is sometimes used in order to protect blood pressure, although propofol, which has ideal antiemetic effects and rapid recovery, is often used at lower doses. Fentanyl + midazolam combined with a non-depolarizing NMBD produces minimal changes in systemic blood pressure and heart rate. Direct laryngoscopy should last < 15 seconds if possible – when not possible, consider spraying 2 mg/kg of lidocaine or injecting 1.5 mg/kg IV lidocaine just prior to DL
Choice of agents often based on patient’s LV function. Volatile anesthetics can provide a controlled myocardial depression, and have been shown to induce ischemic preconditioning, which has been shown to protect the heart from ischemia, at least in rabbit models [Cason et. al. Anesthesiology 87: 1182, 1997]. Still, some physicians use a N2O-opiate technique with sevoflurane reserved for acute treatment of hypertension
According to Baby Miller, boluses of short-acting B-blockers have not been proven effective in reducing cardiac risk
Evidence in Favor of Volatile Anesthetics
A recent meta-analysis of 22 studies, involving 1,922 patients, showed that volatile anesthetics were associated with significant reductions of myocardial infarctions (2.4% vs. 5.1%, p = 0.008) and death (0.4% vs. 1.6%, p = 0.02) [Landoni et. al. J Cardiothorac Vasc Anesth 21: 502, 2007].
Evidence Showing No Benefit Associated With Volatile Anesthetics
A prospective, randomized trial of 1,012 patients at Texas Heart Institute compared enflurane (257), halothane (253), isoflurane (248), or sufentanil (254). From anesthetic induction to start of cardiopulmonary bypass, new ST segment depression appeared in 310 (30.4%) patients and was not different among primary anesthetic groups (28.0-33.5%). Similarly, the incidence of postoperative myocardial infarction (3.6-4.7%) and death (1.2-2.4%) was not different.[Slogoff et. al. Anesthesiology 70: 179, 1989]
Paralysis in Patients With Cardiovascular Disease
Pancuronium is risky as it can increase systemic blood pressure and heart rate, although usually < 15%, although this can sometimes be ideal (ex. when high doses of opiates are used). Atracurium and mivacurium can lower blood pressure slightly. Vecuronium, rocuronium, and cisatracurium do not evoke histamine release and are relatively neutral. Consider not reversing paralysis, as glycopyrrolate is associated with tachycardia, and tachycardia on emergence is associated with post-operative ischemia.
In addition to EKG and intra-arterial catheter, TEE should be considered, but only in high-risk patients (cardiac surgery, recent MI, CHF, or unstable angina). If tachycardia is noted, it should be treated. If ischemia is noted at normal blood pressures, nitroglycerin is appropriate.
Avoid hypothermia. The major predictor of pulmonary complications after cardiac surgery is poor cardiac function. Always provide adequate analgesia and sedation, and alpha/beta blockers as needed.