978-119 Abnormal Left Ventricular Volume Response to Upright Exercise in Patients with Pulmonary Hypertension: Resolution Following Lung Transplantation

Upright exercise in normals is accompanied by an increase in indexed left ventricular end-diastolic volume (LVEDVI) which is felt to enhance cardiac output via the Frank-Starling mechanism. To assess whether an inability to increase LVEDVI during exercise may exist in pts with pulmonary hypertension (PHTN), we examined data from right heart catheterization and rest and exercise first-pass radionuclide ventriculography (RVG) in 55 pts referred for lung transplantation (LTX) evaluation. Grp 1 (n = 16; 46 ± 3 yrs. mean ± SEM) had pulmonary vascular resistance (PVR) ≥ 250 dynes-sec/cm5 (mean 452 ± 44); Grp 2 (n = 39; 48 ± 2 yrs) had PVR l 250 dynes-sec/cm5 (mean 179 ± 6). Pulmonary capillary wedge pressure did not differ between groups (8.2 ± 1.0 vs. 7.2 ± 0.6 mmHg). Right ventricular ejection fraction (RVEF) at rest (0.35 ± 0.02 vs. 0.39 ± 0.01; P l 0.05) and exercise (0.36 ± 0.02 vs. 0.42 ± 0.01; p l 0.005) were lower in Grp 1. All pts reached a pulmonary limit to exercise; exercise capacity. as determined by maximal oxygen consumption or watts achieved. did not differ between groups. Rest and exercise heart rate. indexed LV stroke volume. and LVEF did not differ between groups. Rest Ire) and exercise (ex) LVEDVI. and the change in LVEDVI with exercise. were as follows: Grp1 Grp2 reLVEDVI (ml/m 2 ) 69.9 ± 4.4 69.6 ± 2.2 NS exLVEDVI (ml/m 2 ) 70.5 ± 3.4 82.2 ± 2.6 * ΔLVEDVI (ml/m 2 ) 0.5 ± 2.5 12.6 ± 2.1 * Grp 1 vs. Grp 2 * p l 0.01 19 pts (11 Grp 1.8 Grp 2) underwent LTX with follow-up rest and exercise RVG 15 ± 2 mos later. Following LTX. there was no difference between the groups in exercise capacity or LVEF. and no longer a difference in RVEF or in the ability to increase LVEDVI with exercise. Conclusion Pts with PHTN have an abnormal LVEDVI response to upright exercise which may contribute to their exercise intolerance. This abnormality resolves following LTX.