Kao A C, Van Trigt P, Shaeffer-McCall G S, Shaw J P, Kuzil B B, Page R D, Higginbotham M B
Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
J Heart Lung Transplant. 1995 Jan-Feb;14(1 Pt 1):11-22.
Because prolonged survival of heart transplant recipients is expected with the current immunosuppressive treatment, the functional capacity of these long-term survivors is of interest. Previous exercise studies showed no objective improvement in exercise tolerance several years after transplantation, but the extent to which chronotropic incompetence and allograft diastolic dysfunction observed early after transplantation may improve over time has not been defined.
Thirteen untrained heart transplant recipients without symptoms, between 27 and 70 months after transplantation, and 13 age-matched sedentary normal controls underwent maximal upright bicycle exercise testing with simultaneous hemodynamic, radionuclide, and expired gas measurements.
Systolic function as measured by ejection fraction was supranormal at rest in the transplant group and normalized with exercise. Despite their maximal exercise effort, transplant recipients had a 60% reduction in their exercise capacity compared with nontransplant recipients. Peak oxygen consumption was similarly reduced by 52%. Cardiac output response to exercise was 43% lower in the transplant group because of a 78% reduction in heart rate reserve and an 18% reduction in maximal stroke volume. Ventricular volumes were similarly reduced after transplantation, but filling pressures remained normal, indicating allograft diastolic dysfunction. Despite the significantly reduced maximal cardiac output, maximal arteriovenous oxygen difference was 25% lower in the transplant recipients, suggesting a peripheral deficit in oxygen handling.
Therefore, patients, 2 to 6 years after transplantation, continue to have a significant reduction in exercise tolerance as a result of a combination of severe chronotropic incompetence, limited stroke volume reserve caused by a reduced ventricular size and allograft diastolic dysfunction, and an abnormality in peripheral oxygen delivery or use. Efforts aimed at improving these factors may further enhance the functional capacity of these long-term survivors of heart transplantation.
鉴于目前的免疫抑制治疗有望延长心脏移植受者的生存期，这些长期存活者的功能能力备受关注。以往的运动研究表明，移植后数年运动耐量并无客观改善，但移植后早期观察到的变时性功能不全和同种异体移植舒张功能障碍随时间推移可能改善的程度尚未明确。
13名移植后27至70个月且无症状的未经训练的心脏移植受者，以及13名年龄匹配的久坐不动的正常对照者接受了最大强度直立自行车运动测试，同时进行血流动力学、放射性核素和呼出气测量。
移植组静息时通过射血分数测量的收缩功能超常，运动时恢复正常。尽管移植受者竭尽全力运动，但与非移植受者相比，其运动能力降低了60%。峰值耗氧量同样降低了52%。由于心率储备降低78%和最大每搏输出量降低18%，移植组运动时的心输出量反应降低了43%。移植后心室容积同样减小，但充盈压保持正常，表明存在同种异体移植舒张功能障碍。尽管最大心输出量显著降低，但移植受者的最大动静脉氧差降低了25%，提示外周氧处理存在缺陷。
因此，移植后2至6年的患者，由于严重的变时性功能不全、心室大小减小导致的每搏输出量储备受限、同种异体移植舒张功能障碍以及外周氧输送或利用异常等多种因素，运动耐量持续显著降低。旨在改善这些因素的努力可能会进一步提高这些心脏移植长期存活者的功能能力。
