When autonomic neuropathy involving the cardiovascular system of a diabetic patient is manifested by postural hypotension, it is easily recognizable. Much less obvious and less well known is the effect of the neuropathy on the regulation of the heart rate.
That this effect may be striking could be surmised from animal experiments1 and, more important, from the unique model of cardiac denervation provided by cardiac transplantation in the human. Griepp et al2 demonstrated that the heart rate increased only slightly during the initial phase of exercise in patients with transplanted hearts. A pronounced increase occurred later in exercise, presumably when catecholamines reached the heart after they had been released into the circulation from extracardiac sites. In some patients, the heart rate barely changed during maneuvers designed to stimulate or inhibit the autonomic nervous system.
Lloyd-Mostyn and Watkins3 recently reported a near-total nonsurgical cardiac denervation in a patient