Hemodynamic Response to Acute Volume Load in Heart Transplant Recipients

Purpose A mean pulmonary wedge pressure (mPAP) ≥ 25 mm Hg following volume load or exercise has been proposed as a partition value for detection of HfpEF. However, the hemodynamic response to volume challenge in heart transplant (Tx) recipients has never been studied. Methods 36 heart Tx recipients (Age: 65 years) with normal LV function (EF: 55 ± 7 %) and without rejection and graft vasculopathy underwent right heart catheterization to measure hemodynamic response to volume loading before and after a rapid saline infusion of 7mL/kg over 10 min. PCWP, right atrial pressure (RAP), mean pulmonary artery pressure(PA) were obtained and the PCWP and indexed(i) stroke volume(SV) data were used to construct Starling (SVindex/PCWP) curves. Pts were categorized in those with elevated filling pressures (Group DD, n=10 pts) defined by a PCWP ≥ 15 mm Hg at rest or ≥ 25 mm Hg following volume loading vs those without (Controls, n=26 pts). Results No difference in age of donor and transplant, baseline hemodynamics and EF was noted between both groups. Saline infusion significantly increased PCWP and mean PA in both Groups without any significant change in BP and heart rate. Interestingly saline infusion was associated with a significant rise in SV and SVi in Controls not in DD pts(Fig 1). Moreover, in DD pts the Starling curves revealed a larger SVi at any give PCWP compared to Controls pts. Conclusion In the transplanted heart volume loading increases filling pressures and is able to unmask left ventricular diastolic dysfunction. Interestingly, those with DD are characterized by a blunted Frank Starling response as evidenced by higher PCWP and failure to increase SV for any given PCWP. Further prospective studies are warranted to unravel the underlying mechanisms.