(2017), IXA 2017- Abstracts of the 14th Congress of the International Xenotransplantation Association, Baltimore, USA. Xenotransplantation, 24: n/a, e12328. doi:10.1111/xen.12328
Reliability of Telemetric Monitoring in Pig-to-Baboon Heterotopic Thoracic Cardiac Xenotransplantation
Matthias Längin1,2, Tanja A Mayr1,2, Bruno Reichart2, Alessandro Panelli2,3, Alex Kind4, Paolo Brenner2,3, Jan-Michael Abicht1,2.
1Department of Anaesthesiology, Ludwig-Maximilian University, Munich, Germany; 2Transregio Collaborative Research Center 127, Walter Brendel Centre of Experimental Medicine, Ludwig Maximilian University, Munich, Germany; 3Department of Cardiovascular Surgery, Ludwig Maximilian University, Munich, Germany; 4Chair of Livestock Biotechnology, School of Life Sciences Weihenstephan, Technical University, Munich, Germany
German Xenotransplantation Consortium.
Introduction: The heterotopic thoracic model has been established as an alternative to heterotopic abdominal and orthotopic cardiac pig-to-baboon xenotransplantation. Both hemodynamic and immunological changes can be studied while the recipient’s own heart supports the donor heart. As both hearts are beating separately, monitoring of each of their functional parameters is essential. Furthermore, ECG amplitude and left ventricular pressure have been described as early indicators of graft rejection.Telemetry allows continuous monitoring and recording of hemodynamic parameters. To test the reliability of our own telemetric system, we compared telemetric monitoring with pulse contour analysis in the early perioperative period.
Methods: Wireless telemetry transmitters (DSI PhysioTel®) were implanted subcutaneously in the right medioclavicular line between the 5th and 6th rib. Pressure catheters were placed in the graft’s left ventricle and the recipient’s ascending aorta, ECG leads were sutured to the graft’s epicardium, and body temperature was measured via the transmitter’s housing. In three animals, systemic blood pressure and blood temperature were also assessed via PiCCO-catheter placed in the femoral artery. Donor and recipient’s heart rates were estimated via computerized analysis from recorded telemetric and pulse contour data and double-checked by manual count.
Results: Bland-Altman-plots of telemetric aortal and femoral arterial pressure showed a bias of 7.7 mmHg (±6.9 mmHg, 95% limits of agreement -5.8 and 21.2 mmHg); pressure measurements taken by telemetry were lower than those taken by arterial line (83.2±18.5 mmHg vs 90.7±16.3 mmHg; p<0.001); this also resulted in false negative values of left ventricular end-diastolic pressures in the graft (-4.5±7.4 mmHg). Heart rates from the grafts and the recipients’ own hearts could be distinguished using telemetric ECG, left ventricular and aortal pressure curves. In one case it was possible to diagnose ventricular tachycardia of the donor heart, which would otherwise not have been detectable by standard monitoring. Heart rate estimation by telemetry was more accurate and less prone to artefact than estimation by arterial line (false measurements: 14.2% vs 32.4%, respectively; p<0.001). Due to their positioning, the transmitters reflected the baboons’ body surface temperature rather than core temperature: telemetric temperatures were lower than those measured by arterial line (37.2±0.9°C vs 34.5±2.3°C; p<0.001).
Conclusion: In heterototopic thoracic cardiac pig-to-baboon xenotransplantation, telemetric implants are excellent tools to continuously monitor the animals’ hemodynamic parameters, and to discriminate donor and recipient organs. Heart rate estimation by telemetry is superior to estimation by pulse contour analysis. Pressure measurement inaccuracy is tolerable, but the use of left ventricular end-diastolic pressure as surrogate parameter for preload is not advisable.