Right Ventricular Function After Pulmonary Artery Banding: Adaptive Processes Assessed by CMR and Conductance Catheter Measurements in Sheep.

This experimental study describes the adaptive processes of the right ventricular (RV) myocardium after pulmonary artery banding (PAB) evaluated by cine cardiac magnetic resonance (CMR), phase-contrast CMR (PC-CMR), and conductance catheter. Seven sheep were subjected to CMR 3 months after PAB. Conductance catheter measurements were performed before and 3 months after PAB. Four nonoperated, healthy, age-matched animals served as controls. Higher RV masses (p < 0.01), elevated RV end-systolic volumes (p < 0.05), and lower RV ejection fraction (p < 0.01) were observed in the operated group. The time-to-peak pulmonary artery flow was longer in the banding group (p < 0.01). RV maximal pressure and RV end-diastolic pressure correlated with the time-to-peak flow in the pulmonary artery (r = - 0.70 and - 0.69, respectively). In summary, PAB caused RV hypertrophy, increased myocardial contractility, and decreased RV-EF and cardiac output. The time-to-peak pulmonary artery flow correlated with RV pressures.

Autologous umbilical cord blood mononuclear cell transplantation preserves right ventricular function in a novel model of chronic right ventricular volume overload.

We aimed to evaluate the feasibility and efficacy of autologous umbilical cord blood mononuclear cell (UCMNC) transplantation on right ventricular (RV) function in a novel model of chronic RV volume overload. Four-month-old sheep (n = 20) were randomized into cell (n = 10) and control groups (n = 10). After assessment of baseline RV function by the conductance catheter method, a transannular patch (TAP) was sutured to the right ventricular outflow tract (RVOT). Following infundibulotomy the ring of the pulmonary valve was transected without cardiopulmonary bypass. UCMNC implantation (8.22 +/- 6.28 x 10(7)) in the cell group and medium injection in the control group were performed into the RV myocardium around the TAP. UCMNCs were cultured for 2 weeks after fluorescence-activated cell sorting (FACS) analysis for CD34 antigen. Transthoracic echocardiography (TTE) and computed tomography were performed after 6 weeks and 3 months, respectively. RV function was assessed 3 months postoperatively before the hearts were excised for immunohistological examinations. FACS analysis revealed 1.2 +/- 0.22% CD34(+) cells within the isolated UCMNCs from which AcLDL(+) endothelial cells were cultured in vitro. All animals survived surgery. TTE revealed grade II-III pulmonary regurgitation in both groups. Pressure-volume loops under dobutamine stress showed significantly improved RV diastolic function in the cell group (dP/dt(min): p = 0.043; E(ed): p = 0.009). CD31 staining indicated a significantly enhanced number of microvessels in the region of UCMNC implantation in the cell group (p < 0.001). No adverse tissue changes were observed. TAP augmentation and pulmonary annulus distortion without cardiopulmonary bypass constitutes a valid large animal model mimicking the surgical repair of tetralogy of Fallot. Our results indicate that the chronically volume-overloaded RV profits from autologous UCMNC implantation by enhanced diastolic properties with a probable underlying mechanism of increased angiogenesis.

Pressure-volume loops: feasible for the evaluation of right ventricular function in an experimental model of acute pulmonary regurgitation?

Pressure-volume loop measurements by cardiac catheterization constitute a highly reliable method for the direct beat-to-beat functional analysis of the heart. We aimed to prove its feasibility for the instantaneous evaluation of right ventricular performance in a novel experimental model of pulmonary regurgitation (PR). Four-month-old sheep (n=18, weighing 35-45 kg) were operated via left anterior thoracotomy. A transannular patch (TAP) was sutured to the right ventricular outflow tract (RVOT). Pulmonary valve annulus was transsected through an incision over the patch without the need for cardiopulmonary bypass. Baseline right ventricular function was obtained by inserting conductance catheters through the pulmonary artery before and immediately after surgical induction of PR. All animals survived. Pressure-volume loop analysis presented immediate significant elevations in pressure and volume loading of the right ventricle. Maximum developed pressure incremented from 26.9+/-1.1 mmHg to 30.5+/-0.9 mmHg (P<0.01). End-diastolic volume [62.4+/-3.4-102.7+/-8.6 ml (P<0.01)] increased as well. Peak rate of pressure rise increased during ejection phase, and heart rate rose from 427.1+/-21.4 mmHg/s to 492.6+/-24.7 mmHg/s (P<0.01) and from 89.0+/-3.0/min to 93.0+/-3.3/min (P=0.04), respectively. Right ventricular ejection fraction decreased from 74.1+/-2.7% to 56.6+/-3.0% (P<0.01). Our results demonstrate that the conductance catheter method is feasible for the evaluation of acute right ventricular volume overload in this new model of PR with TAP augmentation of RVOT.