Anish Virdi
Pronouns: He/Him
Research Mentor(s): Alvaro Rojas-Peña
Research Mentor School/College/Department: Department of Surgery-Transplantation / Medicine
Program: UROPF
Session: Session 1 (9:00am – 9:50am)
Authors: Brianna Spencer, Anish Virdi, Spencer Wilhelm, Kristopher Urrea, Vikramjit Chakrabortty, Sebastian Sewara, Daniel Drake, Robert H. Bartlett, Alvaro Rojas-Pena
Abstract
Currently, organs can only be preserved for 4-6 hours via Cold Storage (CS), which is the clinical standard of preservation for transplant organs. This limits the number of transplantable organs, as transportation to the recipient often exceeds 4-6 hours. Normothermic ex-vivo organ preservation has been used as an alternative to CS to assess the function of organs and to extend the preservation time. The M-Flow circuit, developed at UM, has demonstrated successful normothermic perfusion via Langendorf flow, in which the coronaries are perfused directly via oxygenated blood entering the aorta. However, this method of perfusion does not allow for a complete assessment of the heart’s valves and chambers. Therefore, this study aims to establish guidelines for the perfusion of the coronaries via oxygenated blood entering through the left atrium (LA), as it physiologically would. A porcine model was utilized, in which hearts were extracted, cannulated, and perfused on the M-Flow circuit. LA trials 1-4 aimed to perfuse the organ in antegrade fashion at 0.5ml/g/min for 24 hours. Due to the lack of initial contractility leading to insufficient coronary perfusion pressure, modifications were made after n=1 to perfuse in Langendorf for 1 hour before switching to LA for the remaining 23. This allowed time for the effects of cardioplegia, used in extraction, to wear off. These trials, however, failed prematurely as the heart was unable to maintain the pressure differential required for coronary perfusion. This differential can be demonstrated through the equation: Coronary Perfusion Pressure = Aortic (AO) Diastolic Pressure – Left Ventricular End Diastolic Pressure (LVEDP). Venous oxygen saturation (SvO2) values also rose throughout each prep, indicating reduced oxygen utilization resulting from reduced coronary perfusion. The following 4, Intermittent LA (ILA) trials, utilized Langendorf perfusion transitioning briefly to antegrade perfusion every 4 hours at rates of 0.5ml/g/min, 1/ml/g/min, and 0.5/ml/g/min again, each for 5 minutes in that order. Hemodynamics, blood gasses, and settings of the circuit were recorded to guide in intertrial decisions. Pressure waveforms and heart status were also recorded via video during each transition to antegrade perfusion. Each trial lasted 24 hours and CPP was recorded at 13.10mmHg on average, a significant improvement from 7.70mmHg recorded during the LA trials. Additionally, SvO2 did not increase over time. These findings detail the advantages of intermittent LA perfusion over LA perfusion for improving organ longevity and assessment ability.
