Decreased heart rate and blood pressure in a recent cardiac transplant patient after spinal anesthesia.

Abstract

To describe the cardiovascular effects of neuraxial blockade in a heart transplant patient. A 69-yr-old 70-kg male underwent orthotopic heart transplant (bicaval anastomosis technique) for ischemic cardiomyopathy. Five months after transplantation, the patient underwent a transurethral bladder tumour resection under spinal anesthesia. Two millilitres of bupivacaine 0.75% (15 mg) were injected intrathecally at L(3-4) and the patient remained seated for approximately 20 sec prior to assuming the lithotomy position. Subsequently, both blood pressure (BP) and heart rate (HR) diminished gradually (BP and HR immediately pre-spinal: 113 mmHg (mean arterial pressure) and 92 beats x min(-1), respectively; nadir BP and HR: 94 mmHg (16.8% decrease) 30 min postspinal and 73 beats x min(-1) (20.7% decrease) 40 min postspinal, respectively). HR and mean BP were highly correlated (r = 0.9410, P < 0.0001, R(2) = 0.8854). The dermatome level of neuraxial anesthesia, determined by sensitivity to pin prick, was T(8) (five minutes) and T(6) (ten minutes) postinjection of spinal anesthetic. Control patients (n = 10) undergoing elective urological procedures with identical anesthesia management demonstrated very similar cardiovascular responses. Although cardiac transplant patients may tolerate neuraxial anesthesia admirably, a fall in HR may ensue which theoretically could have important physiological consequences. It is argued that the change in HR in the transplanted patient was mediated by mechanisms intrinsic to the transplanted heart and/or by reduced catecholamine secretion from the adrenal medulla. It is emphasized that HR changes observed in cardiac transplant patients do not necessarily imply reinnervation of the transplanted organ.