Impaired left ventricular filling due to right ventricular pressure overload in primary pulmonary hypertension - Noninvasive monitoring using MRI

Objective: To analyze the effect of primary pulmonary hypertension (PPH) on cardiac function using MRI. Methods: In 12 patients (9 women; age range, 30 to 56 years), the diagnosis of PPH had been established by catheterization (mean +/- SD pulmonary arte ry pressure [PAP] was 56 +/- 8 mm Hg). With breath-hold cine MRI, a series of short-axis images was acquired covering the whole left ventricle (LV) an d right ventricle (RV), The curvature, defined as 1 divided by the radius o f curvature in centimeters, was calculated for the septum and the LV free w all in early diastole, Leftward ventricular septal bowing (LVSB) is denoted by a negative curvature, For the LV and the RV, the end-diastolic volume ( EDV), stroke volume (SV), and volumetric filling rate were calculated. The control subjects were all healthy (n = 14; 11 women; age range, 20 to 57 ye ars). Results: In the patients, LVSB was quantified in early diastole by the sept al curvature of - 0.14 +/- 0.07 cm(-1), and the septal to free-wall curvatu re ratio of - 0.42 +/- 0.21, LV EDV and LV SV correlated negatively with di astolic PAP (p = 0.004 and p = 0.04, respectively), In patients vs control subjects, RV SV: was reduced (52 +/- 12 mt vs 82 +/- 11 mL, p < 0.0001); LV peak filling rate was smaller (2.2 +/- 0.7 EDV/s vs 3.3 +/- 0.5 EDV/s, p < 0.001); LV EDV was smaller (81 +/- 23 mt vs 117 +/- 19 mt, p = 0.001); and LV SV was smaller (49 +/- 18 mt vs 83 +/- 13 mt, p < 0.0001). Conclusion: In PPH, RV pressure overload leads to LVSB and reduced RV outpu t. By decreased blood delivery, LV filling is reduced, which results in dec reased LV SV by the Frank-Starling mechanism.