A hypodynamic circulation should be continued until the day of operation by an effective regimen of β-blockers and calcium channel blockers. If preinduction heart rate is not effectively controlled by adequate β-blockade, intravenous propranolol or esmolol can be given to slow heart rate. Appropriate premedication is needed to avoid hypertension and tachycardia from anxiety in the preoperative period. Additional intravenous sedation and analgesia may be required during placement of invasive monitors. Unpremedicated patients show increased heart rate, blood pressure, and MVO(02) when compared with well-sedated patients. If general anesthesia is elected, induction with moderate doses of intravenous high-potency narcotics save and smooth and can be followed by a potent inhaled agent before intubation to prevent autonomic response. Although currently controversial in the clinical setting, isoflurane has the potential to dilate normal segments of the coronary vascular bed in patients with coronary artery disease with consequent occurrence of regional myocardial ischemia. Nitrous oxide is not necessary for anesthetic purposes and involves a risk of myocardial ischemia which may not be identifiable by ECG. Blood pressure and heart rate should be kept at or below baseline levels as a means of preserving myocardial oxygen balance distal to coronary lesions. Administration of intravenous nitroglycerin can be used to keep blood pressure at desired depressed level while reducing cardiac work, MV(02) and ST segment changes. If inotropic support is required dobutamine, amrinone, or intravenous CaCl2 can be given slowly, without upsetting myocardial oxygen balance.
|Original language||English (US)|
|Number of pages||5|
|Journal||Acta Anaesthesiologica Scandinavica, Supplement|
|State||Published - Jan 1 1991|
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine