Carotid sinus stim: post-heart transplant

Orthotopic heart transplantation results in total autonomic denervation of the heart. In this situation, carotid sinus stimulation will have minimal effects as the autonomic nervous system loop is not intact in order to effect heart rate change. Whether reinnervation occurs has been a matter of some debate. Some small longitudinal studies have indicated that reinnervation occurs as time progresses after heart transplant. A small study in 2000 by Uberfuhr and colleagues evaluated non-invasive carotid baroreflex stimulation in heart transplant patients and found that sympathetic innervation was restored in some patients, beginning at one year after transplantation.[1] Evidence for parasympathetic reinnervation occurred in this study, but at a later time and much less frequently than sympathetic reinnervation, and only in patients who already had evidence of sympathetic rein nervation.

There are two main techniques for anastomosis of the cardiac graft. One such technique involves sewing donor right and left atria to recipient right and left atrial cuff remnants (biatrial technique). The bicaval technique involves sewing the donor left atrium to a single recipient left atrial cuff, including the native pulmonary veins. One of the small studies regarding reinnervation, done by Bernardi and colleagues, indicated that patients receiving the bicaval technique of anastomosis had enhanced sympathetic reinnervation.