A Novel Intraventricular Balloon Technique for Functional Assessment of Hearts from Donation After Circulatory Death

Abstract

<h3>Purpose</h3> Functional assessment of hearts from donation after circulatory death (DCD) on ex-vivo heart perfusion (EVHP) is not well-established. Conventional intraventricular balloon (IVB) techniques, used for isolated heart perfusion in large animal models sacrifice the mitral valve to stabilize the balloon inside the left ventricle (LV), making it inapplicable for the clinical setting. This study demonstrates the effectiveness of a novel IVB technique to assess cardiac function during reperfusion and compares it to pressure-volume catheter measurements in a pediatric porcine DCD heart model. <h3>Methods</h3> Twelve pigs (9.5 ± 1.4 kg) were used. DCD hearts were harvested after 15 min of global warm ischemia due to asphyxic circulatory arrest and reperfused on EVHP for 2 hours. Isovolumetric LV pressure was measured during reperfusion with a saline-filled balloon inserted into the LV via a pulmonary vein orifice. The balloon was made from polyethylene wrap and connected to an 8 Fr sheath and pressure catheter, which was fixed with the left atrium via a purse-string suture around the origin of the pulmonary vein. DCD hearts were then switched to the working model (WM), pumping 120% of cardiac output, to measure cardiac function by using a pressure-volume catheter. Between-parameter correlations were assessed by Spearman's Rank Correlation Coefficient. <h3>Results</h3> Maximum first derivative of the LV pressure (dp/dt) measured by the IVB at 90 min of reperfusion showed moderate positive correlation (r_s = 0.61, p = 0.04) and coronary venous lactate levels showed moderate negative correlation (r_s = -0.55, p = 0.06) to respective measurements in the WM. Minimum dp/dt measured by the IVB at 60 min of reperfusion showed moderate positive correlation to measurements in the WM (r_s = 0.60, p = 0.04) and to tau in the WM (r_s = 0.52, p = 0.08). There was no significant difference between LV end-diastolic pressure during reperfusion and left atrial pressure in the WM. Myocardial oxygen consumption during reperfusion was less than 60% of that in the WM. <h3>Conclusion</h3> Functional parameters of contractility and relaxation measured by the IVB showed significant correlations to respective parameters in the WM. Therefore, this mitral valve sparing IVB technique can be used to confirm adequacy of cardiac function of DCD hearts in the early phase of reperfusion without the need to fully preload the heart.