Chapter 56: Regional Anesthesia for Cardiac and Thoracic Anesthesia

REGIONAL ANESTHESIA FOR CARDIAC SURGERY

General anesthesia is the most commonly used anesthetic technique for cardiac surgery, both for valvular procedures and for coronary artery bypass grafting (CABG) performed either on pump or off pump. However, there are several reports from the 1970s and 1980s describing improved postoperative analgesia through the intrathecal and epidural application of opiates in cardiac surgery.^1,2 Faster extubation of patients is another benefit of the neuroaxial application of opiates.³ Local anesthetics are also routinely applied as they suppress the stress hormone response in addition to having analgesic properties, resulting in improved outcomes.⁴

For intrathecal application, two procedures have been reported: opiates or the “high spinal technique,” achieved with large doses of local anesthetic. In contrast to a single-shot intrathecal technique, epidural opiates and local anesthetics can be applied continuously. As a result, the intraoperative benefits of a neuraxial procedure can be continued beyond the postoperative phase. Intrathecal and epidural procedures are typically combined with a general anesthetic, although segmental pain elimination allows for cardiac procedures through the sole use of a high thoracic epidural anesthesia.⁵

Paravertebral blockade (PVB) is another reported regional anesthetic procedure in cardiac surgery (Table 56–1).⁶ Varying techniques are used: single-shot or continuous application; unilateral for thoracotomy or bilateral for sternotomy.^6,7 Due to the limited number of published cases, the importance of PVB in cardiac surgery currently cannot be assessed.

Techniques

High Thoracic Epidural Anesthesia

Despite some beneficial effects of regional anesthesia, especially the neuraxial techniques, its use is not yet widely accepted in cardiac surgery. This is due to the ongoing discussion regarding the potential risks of epidural hematoma formation and subsequent adverse neurological sequelae related to perioperative anticoagulation, which thus discourages the use of epidurals in these patients by many anesthesiologists. There is a great deal of controversy in the cardiac literature concerning neuraxial techniques in cardiac surgery.^8,9

Physiological Effects

High thoracic epidural anesthesia (hTEA) results in excellent analgesia achieved throughout the epidural application of opiates and/or local anesthetics, allowing for faster recovery and extubation after surgery.^10.11 This is due to the superior analgesia of hTEA after CABG surgery, which may improve respiratory muscles strength.¹²

Beyond its analgesic properties, hTEA’s beneficial effects on the postoperative neurohumoral stress response and cardiovascular pathophysiology have been demonstrated in both clinical and experimental investigations. hTEA results in a segmental thoracic sympathectomy; at a level between T1 and T5, this sympatholysis dilates the coronary arteries and the internal mammary arteries and thus ...