ABSTRACT
Objective:To investigatethe relationship between right ventricular blood flow components and right ventricular function in patients with pulmonary hypertension (PH) by 4D-FLOW cardiovascular MR (4D-FLOW CMR).Methods:Thirty patients with PH were prospectively enrolled in this study. All patients underwent right heart catheterization to measure hemodynamics and CMR to measure right ventricular blood flow and right ventricular function within 1 week. The long-axis 4-chamber and contiguous short axis cineslices were acquired with balanced steady-state free precession sequence to calculate RV functional metrics including right ventricular end diastolic volume, end systolic volume, ejection fraction, stroke output and other functional parameters. Ventricular flow was acquired in sagittal direction, using a 3D retrospectively ECG-triggered, navigator-gated prototype sequence to analyze.RV function and flow parameters were correlated with Spearman correlation analysis.Results:Right ventricular percent of direction flow(RVPDF),percent of delayed eject flow (RVPDEF),percent of retained flow (RVPRI) and percent of residual volume(RVPRV) of PH patients measured with 4D-FLOW were 16.4%±9.2%, 16.1%±5.6%, 16.8%±6.1%, and 50.5%±12.3%, respectively. RVPDF negatively correlated with RVPRVo ( r=-0.703, P<0.001) while RVPDEF positively correlated with RVPRI( r=0.955, P<0.001). RVPDF was positively correlated with right ventricular stroke volume index (RVSVI)( r=0.38, P=0.041) and right ventricular eject fraction(RVEF)( r=0.69, P<0.001), and negatively correlated with right ventricular end systolic volume index(RVESVI)( r=-0.65, P<0.001) and right ventricular mass index(RVMI)( r=-0.45, P=0.004). RVPRVo was negatively correlated with RVEF( r=-0.58, P=0.007). The sum of RVPDF and RVPDEF (RVPDF+RVPDEF) was 35.2%±11.4%. RVEF correlated with RVPDF+RVPDEF ( r=0.825, P<0.001) and comparable to RVPDF+RVPDEF ( t=1.427, P=0.164). RVPDF was negatively correlated with pulmonary vascular resistance (PVR) ( r=-0.52, P=0.007) while RVPRVo was positively correlated with PVR ( r=0.54, P=0.004). Conclusions:4D-FLOW CMR can be used to measure right ventricular ejection fraction in PH patients without respiratory control. In PH patients, the right ventricular direct blood flow was significantly decreased, while the residual blood flow was significantly increased. The right ventricular direct blood flow and residual blood flow were related to the right ventricular function and pulmonary vascular resistance, which were important parameters to evaluate the right ventricular function and afterload in PH.
ABSTRACT
Objective@#To compare the value of right ventricular (RV) free wall longitudinal strain (FWLS) by speckle tracking echocardiography (STE) and conventional parameters in evaluation of RV dysfunction in chronic thromboembolic pulmonary hypertension (CTEPH).@*Methods@#Sixty CTEPH patients were enrolled as group A and 45 pulmonary embolism (PE) patients with normal pulmonary pressure were enrolled as group B in this study. CTEPH patients were divided into 2 subgroups using the World Health Organization (WHO) function classification: patients with WHO Ⅰ-Ⅱ were designated as group A1 and those with WHO Ⅲ-Ⅳ were designated as group A2. Conventional RV functional parameters including tricuspid annular plane systolic excursion (TAPSE), tissue Doppler-derived tricuspid annular systolic velocity (S′), fractional area change (FAC), RV index of myocardial performance (RVIMP), and STE-derived RV FWLS were measured and compared. Clinical right heart failure (RHF) was defined as the presence of symptoms of heart failure and signs of systemic circulation congestion during hospitalization.@*Results@#Compared to group B, group A patients had significant enlarged right heart dimension and impaired RV systolic function parameters (all P<0.001). The TAPSE, S′, FAC, and RV FWLS showed significant differences between CTEPH patients with mild (group A1) and severe symptoms (group A2) (all P<0.01), while RVIMP showed no significant difference (P=0.188). On receiver operating characteristic analysis, FWLS had the largest AUC to identify RHF (AUC=0.864, P<0.001), when the cutoff value was 15.05%, the sensitivity was 85.71%, and the specificity was 64.29%, respectively. On binary logistic regression analysis, only right atria area (OR=1.212, 95%CI=1.004-1.48, P=0.046) and RV FWLS (OR=0.662, 95%CI=0.470-0.933, P=0.018) were identified as independent predictor of RHF.@*Conclusions@#Compared with conventional parameters, RV FWLS showed advantages in identifying abnormal RV function in CTEPH patients.