The decision to utilize regional anesthesia is dependent on many factors. Patient characteristics, the type of surgery proposed, and the potential anesthetic risks will all have an impact on anesthetic choice and perioperative management. In patients with cardiovascular disease, regional anesthesia techniques (either alone or in conjunction with general anesthesia) can offer the potential perioperative benefits of stress response attenuation, cardiac sympathectomy, earlier extubation, shorter hospital stay, and intense postoperative analgesia. However, the decision to utilize regional anesthesia should be made with caution in some circumstances. The aim of this chapter is to provide an overview of the physiological effects of different regional anesthesia techniques on the cardiovascular system, to examine the role of regional anesthesia in cardiac surgery and noncardiac surgery and to provide an overview of the physiological requirements of patients with different types of cardiac and vascular disease.
THE CARDIOVASCULAR EFFECTS OF REGIONAL ANESTHESIA
Thoracic Epidural Anesthesia
High thoracic epidural anesthesia (TEA) from T1–T5 blocks the cardiac afferent and efferent sympathetic fibers with a loss of chronotropic and inotropic drive to the myocardium1 and reduced perception of cardiac pain.
In healthy volunteers, there is some evidence that thoracic epidural blockade reduces left ventricular contractility as measured by transesophageal echocardiography2 and that this effect is present in high thoracic epidural blockade but not in low thoracic epidural blockade,3 which is consistent with a loss of inotropic drive to the myocardium with high epidural blockade. During exercise, it has been reported that TEA does not affect oxygen consumption (VO2) but does reduce systemic arterial blood pressure compared to control subjects.4 Another study compared the cardiovascular effects of 0.5% bupivacaine administered via the thoracic epidural route against the effects when administered via the intramuscular route and found no significant difference and postulated whether the effects of epidural anesthesia may in part be due to systemic effects. However, their conclusions are limited by the low number (9) of subjects enrolled.5
Several studies have documented the effects of TEA on cardiovascular function in patients with heart disease. In a small study of 10 patients scheduled for thoracotomy, a TEA with a mean analgesic level of C7 to T5 had only minor effects on the cardiovascular system.6 In patients with severe coronary artery disease and unstable angina pectoris, Blomberg et al observed that TEA relieved chest pain.7 It also significantly decreased heart rate and systolic arterial, pulmonary arterial, and pulmonary capillary wedge pressures without any significant changes in coronary perfusion pressure, cardiac output, stroke volume, or systemic or pulmonary vascular resistances. The investigators also found that TEA may increase the diameter of stenotic epicardial coronary arteries in patients with coronary artery disease without causing a dilation of coronary arterioles.8
Intraoperatively, during abdominal aortic aneurysm surgery, Reinhart et al observed a lower cardiac index and O...