Contractility of the transplanted, denervated human heart

Heart transplantation is a therapeutic strategy used for a variety of severe, incurable cardiac disorders. A complete characterization of the alterations that take place in the heart following implantation in the recipient is important to understanding the recovery process. One important difference between the pre- and postimplantation environments of the heart is that the autonomic nerves (which affect heart rate, contractility, and other aspects of cardiac function) are severed when the heart is removed from the donor, and do not regenerate in the recipient to any significant degree. To characterize the contractility of the transplanted, denervated heart, a study was carried out involving 34 heart patients and 20 healthy control patients of similar ages. Heart transplant patients were receiving various combinations of immunosuppressive drugs, anti-inflammatory steroids, and calcium channel blockers. The average contractility index (which reflects the force of contraction) did not differ between transplant patients and controls, and contractility did not show any evidence of being increasingly impaired as the time since transplant increased, or as a result of mild episodes of immune rejection of the transplanted heart. A small number of subjects (12 percent) did have mildly impaired contractility that could not be attributed to any measure being monitored; pretransplantation damage to the heart muscle may have been the causal factor in those cases. Hence, normal contractility appears to be an intrinsic property of the heart, and not dependent on extrinsic innervation. (Consumer Summary produced by Reliance Medical Information, Inc.)