A Non-invasive Evaluation Study Of Pulmonary Vascular Resistance In Rheumatic Mitral Valve Lesions

Objective: Pulmonary vascular resistance(PVR) reflects vascular resistance of pulmonary circulation, which is an important clinical indicator in assessing pathological and physiology situation of pulmonary vascular bed, monitoring pulmonary hypertension(PH) progress, as well as guiding internal medicine and surgical decision-making and preliminary judging the prognosis of cardiovascular diseases. For a long time, right cardiac catheterization(RHC) is the gold standard for clinical evaluation of PVR. Although PVRcath by RHC is accurate, reliable, but invasive and risky characteristics of which greatly restricted its widely application in clinic. In this study we measured maximum velocity tricuspid regurgitation velocity(TRV)(echo) and right ventricular outflow tract velocity-time integral(VTIrvot) by echocardiography and calculated the ratio of TRV and VTIrvot(TRV/VTIrvot), proposed to explore regression relationship between TRV/VTIrvot and PVRcath by "gold standard" RHC, and analyze the PVR change rule of patients with rheumatic mitral valve lesions, providing an accurate and reliable imaging data support for clinicians to diagnose and treat such patients.Methods: 1 Subjects Non-continuous 67 in-patients with rheumatic mitral valve lesions from May 2013 to December 2014 in our hospital were enrolled in our study, male 23 and female 44, aging 17 to 49 years old, mean age 38.4±10.7 years, body surface area(BSA) of 23.9±4.7 kg/m2.Inclusion criteria: ?without other congenital and acquired organic cardiovascular lesions;?sinus rhythm;? systolic pulmonary artery pressure(SPAP)≥40mm Hg;?left ventricular ejection fraction > 50% and without significant abnormal in left ventricular diastolic function;⑤without history of lung diseases.2 Methods 2.1 Echocardiography Philips IE33 ultrasound system and S5-1 transthoracic echocardiography transducer S5-1(1-5MHZ) were used in our study, and synchronous electrocardiogram was recorded. Patients took the left side at resting state, with calm breathing. 2.1.1 Conventional hemodynamic parameters measurement: we measured mitral valve area(MVA),maximum mitral regurgitation pressure(MRP), trans-aortic valve pressure, left ventricle size(LV), left ventricle ejection fraction(LVEF),pulmonary artery width, systolic tricuspid valve annulus shift. 2.1.2 The measurement and calculation of main research indexes: we measured maximum tricuspid regurgitation velocity(TRV) and right ventricular outflow tract velocity-time integral(VTIrvot) by echocardiography and calculated the ratio of TRV and VTIrvot(TRV/VTIrvot) and SPAP =TRP+RAP. 2.2 Right cardiac catheterization(RHC) RHC was performed before patients underwent mitral valve replacement or balloon expansion to measure mean pulmonary artery pressure(PAMP) and pulmonary artery wedge pressure(PAWP), and the flow volume to the lungs(pulmonary quantity, Qp) and calculated PVRcath according to Poiseuille formula(PVR = PAMP- PAWP/Qp). Echocardiography was performed within 6h after 6h. 2.3 Data analysis Then analyze regression relationship between TRV/VTIrvot and PVRcath by RHC, proposed to explore the PVRcath the regression equation between them, analyzes the accuracy, sensitivity, specific and reproducibility of TRV/VTIrvot predicting PVR, and explore the PVR changing rule of patients with rheumatic mitral valve lesions. 3 Statistical methods SPSS19.0 statistical software was used for data analysis. Data normality was tested by Kolmogorov-Smirnov. Continuous variables were expressed bymean±standard deviation. Pearson correlation regression was used to analyze relationship between TRV/VTIrvot by echo and PVRcath by RHC, P < 0.01 was considered that the difference was statistically significant. Bland-Altman analysis was used for consistency evaluation between PVRecho and PVRcath. ROC curve was used for analyzing s of TRV/VTIrvot predicting PVR>2WU.Count data were expressed by frequency(rates).Results: 1Comparison analysis between TRV/VTIrvot and PVRcath 1.1 correlation There was significant correlation between TRV/VTIrvot and PVRcath(r=0.93,P<0.01); 1.2 consistency Bland-Altman analysis suggested that there was perfect consistency between PVRecho and PVRcath; 1.3 sensitivity and specificity ROC curve analysis showed that the sensitivity and specificity of TRV/VTIrvot = 0.17 predicting PVR > 2 WU were 93.6% and 73.6% respectively. 1.4 Reproducibility The correlation coefficient between inter-observers and intra-observers was0.875 and 0.917 respectively, suggesting that PVR derived from echo was repeatability. 2 Correlation analysis between SPAP and PVRcath The overall relationship between SPAP and PVRcathis linear positive correlation(r = 0.90, P < 0.01), of which more than moderate PH correlation(r = 0.91) was increased significantly relative to mild PH(r = 0.56).Conclusions: This study showed that there was significant correlation between TRV/VTIrvot derived from echo and PVRcath by RHC, providing an accurate and reliable imaging data support for condition monitoring, treatment strategies decision-making, prognosis judging and postoperative follow-up forelevated PVR evaluation in patients with rheumatic mitral valve lesions.