Principles of exercise testing and interpretation

Combined heart-kidney transplant improves post-transplant survival compared with isolated heart transplant in recipients with reduced glomerular filtration rate: Analysis of 593 combined heart-kidney transplants from the United Network Organ Sharing Database

Heart transplantation (HTx) surgically interrupts the parasympathetic vagal neurons and the intrinsic postganglionic sympathetic nerve fibers traveling from the stellate ganglia to the myocardium, causing axonal Wallerian degeneration and thus extrinsic cardiac denervation.[1][1], [2][2], [3][3], [4

Early Denervation and Later Reinnervation of the Heart Following Cardiac Transplantation: A Review.

There has been significant progress in the field of heart transplantation over the last 45 years. The 1-yr survival rates following heart transplantation have improved from 30% in the 1970s to almost 90% in the 2000s. However, there has been little change in long-term outcomes. This is mainly due to chronic rejection, malignancy, and the detrimental side effects of chronic immunosuppression. In addition, over the last decade, new challenges have arisen such as increasingly complicated recipients and antibody-mediated rejection. Most, if not all, of these obstacles to long-term survival could be prevented or ameliorated by the induction of transplant tolerance wherein the recipient's immune system is persuaded not to mount a damaging immune response against donor antigens, thus eliminating the need for chronic immunosuppression. However, the heart, as opposed to other allografts like kidneys, appears to be a tolerance-resistant organ. Understanding why organs like kidneys and livers are prone to tolerance induction, whereas others like hearts and lungs are tolerance-resistant, could aid in our attempts to achieve long-term, immunosuppression-free survival in human heart transplant recipients. It could also advance the field of pig-to-human xenotransplantation, which, if successful, would eliminate the organ shortage problem. Of course, there are alternative futures to the field of heart transplantation that may include the application of total mechanical support, stem cells, or bioengineered whole organs. Which modality will be the first to reach the ultimate goal of achieving unlimited, long-term, circulatory support with minimal risk to longevity or lifestyle is unknown, but significant progress in being made in each of these areas.

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Heart Transplantation: Challenges Facing the Field

Purpose of reviewWhen it comes to tolerance induction, kidney allografts behave differently from heart allografts that behave differently from lung allografts. Here, we examine how and why different organ allografts respond differently to the same tolerance induction protocol.Recent findingsAllograf

Organ-specific differences in achieving tolerance.

Background The role of solid multiorgan transplantation remains to be determined. We compared our experience with combined heart-kidney transplantation (HKT) and heart transplant alone (HT), and assessed patient survival rates and freedom from allograft rejection in these two patient groups. Methods We reviewed the clinical outcomes of patients undergoing HKT (n = 30) or HT (n = 440) between June 1992 and March 2009. Baseline patient characteristics, perioperative factors, incidence of rejection, and survival were examined. Results There were no significant differences between the two groups for age, gender, etiology of heart disease, functional class, preoperative left ventricular ejection fraction, end-diastolic diameter, cardiac output, or transplant waitlist status. Patients with HKT had a higher serum creatinine level (P .05 for all comparisons). Conclusions HKT offers excellent survival and similar renal function when compared with HT alone. Patients with end-stage cardiac and renal failure can be considered for HKT.

Survival and allograft rejection rates after combined heart and kidney transplantation in comparison with heart transplantation alone

Background The standard biatrial technique for orthotopic heart transplantation uses a large atrial anastomosis to connect the donor and recipient atria. A modified technique involves bicaval and pulmonary venous anastomoses and is believed to preserve the anatomic configuration and physiological function of the atria. Bicaval heart transplantation reduces postoperative valvular regurgitation and is associated with a lower incidence of pacemaker insertion. Objective The aim of this study was to compare postoperative functional capacity and exercise performance in patients with bicaval and biatrial orthotopic heart transplantation. Methods Patients were selected for the study if they did not have any of the following: obstructive coronary artery disease (>50% stenosis), severe mitral or tricuspid regurgitation, signs of rejection (grade ≥1B-1R) on endomyocardial biopsy during the prior year, respiratory impairment, a permanent pacemaker, orthopedic or muscular impediments, or lived more than 150 miles from the medical center. A total of 27 patients qualified. In 15 patients who received a biatrial heart transplant and 12 patients with a bicaval heart transplant, a stationary bicycle exercise test was performed. Ventilatory gas exchange and maximum oxygen consumption measurements were measured. Results Recipient and donor characteristics, including body surface area, donor/recipient weight mismatch, immunosuppressive regimen, and self-reported weekly exercise activity, did not differ between the biatrial and bicaval groups (P = not significant [NS]). At peak exercise, similar heart rate, workload, oxygen consumption, carbon dioxide production, ventilation, functional capacity, and exercise duration were found between the 2 groups (P = NS). Patients in the biatrial group were studied later than patients in the bicaval group (6.54 ± 0.71 vs 4.68 ± 0.28 years; P Conclusion There were no significant differences in the exercise capacity between patients with biatrial versus bicaval techniques for orthotopic heart transplantation. Factors other than the atrial connection (such as cardiac denervation, immunosuppressive drug effect, or physical deconditioning) may be more important determinants of subnormal exercise capacity after heart transplantation. Nevertheless, the reduction in morbidity and postoperative complications and the simplicity in the bicaval technique suggest that bicaval heart transplantation offers advantages when compared with the standard biatrial technique.

S.P. Gallagher

Papers

Survival and allograft rejection rates after combined heart and kidney transplantation in comparison with heart transplantation alone

Exercise Performance Comparison of Bicaval and Biatrial Orthotopic Heart Transplant Recipients