Effects of bupivacaine and lidocaine on cardiac function in awake and pentobarbital-anesthetized rats.

Using an implanted Doppler crystal, we evaluated emodynamic changes induced by subconvulsive doses of bupivacaine and lidocaine in awake and pentobarbitalanesthetized rats. Low doses of lidocaine (2.0 mg·kg) and bupivacaine (0.5 mg·kg) changed hemodynamics minimally. However, a high dose of lidocaine (8.0 mg·kg) reduced heart rate, cardiac output, and regional myocardial wall thickening for a short period with or without anesthesia. In contrast, a high dose of bupivacaine (2.0 mg·kg) increased mean arterial pressure and did not change heart rate or regional myocardial wall thickening in the awake state. Under pentobarbital anesthesia, a high dose of lidocaine reduced mean arterial pressure significantly shortly after the injection, but bupivacaine did not. Thus, it is unlikely that bupivacaine has more potent cardiotoxicity than lidocaine in subconvulsive doses.