Perioperative Telemetric Monitoring in Pig-to-Baboon Heterotopic Thoracic Cardiac Xenotransplantation

Abstract

BackgroundPerioperative monitoring and hemodynamic management after heterotopic thoracic cardiac xenotransplantation is challenging due to 2 independently beating hearts. Telemetry allows continuous monitoring of hemodynamic parameters of both the donor and recipient hearts. We describe our experience and report on the validity of a telemetric system during and after surgery.Material/MethodsWireless telemetry transmitters were implanted in 3 baboons receiving porcine donor hearts. Left ventricular pressure and ECG were assessed from the donor heart, whereas aortic pressure and temperature were assessed from the recipient. Telemetric data were validated with invasive blood pressure measurements.ResultsTelemetric blood pressure was lower than invasive blood pressure. Intraoperatively, the probe in the graft’s left ventricle measured negative end-diastolic pressures. Telemetry allowed simple discrimination between donor’s and recipient’s heart rates. Body temperature was underestimated by telemetry. Telemetric monitoring facilitates recognition of graft arrhythmias and volume demand.ConclusionsIn heterotopic thoracic cardiac xenotransplantation, telemetric implants are useful tools to continuously monitor the animals’ hemodynamic parameters and to discriminate donor and recipient organs. Accuracy is sufficient for systemic pressure measurement, but perioperative use of left ventricular end-diastolic pressure as a surrogate parameter for graft function is not advisable. Temperature measurements by telemetry do not reflect body core temperature.

Current spectrum, challenges and new developments in the surgical care of adults with congenital heart disease

“…The shortage of organs remains a problem in most countries. Therefore, further efforts to explore the opportunities of xenotransplantation are justified (72).…”

Current Status of Cardiac Xenotransplantation: Report of a Workshop of the German Heart Transplant Centers, Martinsried, March 3, 2023

“…Pig breeds used for XT experiments, such as German Landrace or Large White, weigh outgrown 200 to 300 kg, resulting in proportionately large hearts of approximately 1 kg, much too big for a human recipient, not to mention a baboon weighing between 15 and 20 kg. While it was previously believed that grafts would adapt to recipient growth regulation, recent findings 7 38 indicate that donor organ growth is genetically regulated: the porcine donor heart behaves as if it is still in a fast-growing pig's body; additionally, elevated afterload in baboon recipients causes concentric myocardial hypertrophy of juvenile porcine grafts. In combination, these intrinsic (donor-specific) and extrinsic (recipient-specific) factors led to extensive cardiac overgrowth and the development of dynamic outflow tract obstruction in preclinical experiments.…”

“…In contradistinction, the risk of hyper-acute/humoral rejection of a cardiac xenograft could be reduced significantly due to multiple genetic modifications of the donor pigs. 7 18 In 2000, the Xenotransplantation Advisory Committee of the International Society of Heart and Lung Transplantation set up criteria, when the first clinical trial should be considered. 83 The required preclinical results have been met: consistent survival of two-third of the life-supporting porcine heart replacements in NHPs, in good health for up to a minimum of 3 months (has recently been extended for 6 months, or in single case longer).…”

Porcine Orthotopic Cardiac Xenotransplantation: The Role and Perspective of Anesthesiologists

“…Vital signs were monitored by direct observation and with a surgically implanted hemodynamic telemetric monitoring device. 25 Lessons Learned Before the First Pig-to-Human Cardiac Xenotransplant Multiple years of experience with orthotopic cardiac xenotransplantation guided the authors' decision-making and prepared them for the clinical challenge of a porcine cardiac transplant into a human patient. Prior knowledge and experience in allograft transplantation, along with medication regimens and exposure to PCXD in the pig-to-baboon model, were brought to the operating room on January 7.…”