The Association Of Functional Classification With Right Atrial Deformation In Patients With Pulmonary Arterial Hypertension:study With Two-dimensional Speckle Tracking

Objective:To assess right atrium(RA) myocardial longitudinal deforma- tion in pulmonary hypertension(PH) patients using two-dimensional speckle t- racking echocardiography(2D-STE),and define the relationship between RA function and exercise capacity in PH patients.Methods: 1 Thirty-eight patients with chronic pulmonary artery hypertension were enrolled as the experimental group,all patients had a mean pulmonary aterial pressure(m PAP)>25mm Hg and a normal pulmonary artery wedge pressure(PCWP)<15mm Hg.The patients were divided into three groups by WHO classification.(1)PH WHO-FC class II(n=19,mean age of 42±16 years),(2)PH WHO-FC class Ⅲ(n=11,mean age of 45±18 years),(3)PH WHO-FC class Ⅳ(n=8,mean age of 54±12 years).We selected 27 healthy volunteers who were matched age and gender with the pulmonary arterial hypertension patients to serve as controls(n=20,mean age of 40±12 years).The volunteers had no related medical history;physical examination,ultrasound echocardiography, electrocardiogram(ECG)and laboratory tests showed no abnormality. 2 A commercially available Vivid E9 ultrasound machine(GE Healthcare) equipped was employed,with a probe of M5 S,probe frequency of 1.7~3.4MHz. Echo PAC v110 workstation was available for quantitative analysis of 2D-STE. 3 All echocardiography studies were performed with the subjects in the left lateral decubitus position.All subjects kept a quite breathe and were connected with ECG.We recorded the data,such as gender,height(H),weight(W),blood pressure(BP)and heart rate(HR),and calculated body surface area(BSA). 4 Parameters measurement and image analysis 4.1 Parameters of the conventional two-dimentional echocardiography:rightatrium diameter(RAD),RA end-systolic area,Maximum RA area,right ventric- ular basal diameter,RV end-diastolic area,RV subcostal wall thickness,left ven- tricular end-diastolic diameter(LVDD),LVEF,tricuspid annular plane systolic excursion,RV myocardial performance index(RV MPI), isovolumic relaxation time(IRT),systolic S-wave(S’)from tissue Doppler imaging. 4.2 Systolic pulmonary artery pressure(SPAP)measurement:SPAP was calcula- ted from the maximal velocity of tricuspid regurgitation(TR)and RAP using Bernoulli’s equation(SPAP =4VTR2 + RAP).RAP was estimated by the respi- ratory motion and the size of the inferior vena cava(IVC)from the subcostal view.IVC diameter≤21mm that collapses>50% suggests normal RA pressure of 3 mm Hg(range, 0-5 mm Hg);IVC diameter>2.1 cm that collapses <50% suggests high RA pressure of 15 mm Hg(range,10-20 mm Hg);If IVC diamet- er and collapse do not fit this paradigm,an intermediate value of 8 mm Hg(range,5-10 mm Hg)was used. 4.3 Image acquisition of Speckle Tracking Echocardiography and image anal- ysis:Apical four chamber views images were obtained using conventional two dimensional gray scale echocardiography.Care was taken to obtain true apical images and not foreshorten the size of RA.The operator should minimize the depth and angle to incease the frame rate.The frame rate was set between 60 and 80 frames/s.Three consecutive heart cycles were recorded during breath- hold with stable ECG recording and stored for off-line analysis. Two-dimensional echocardiography images were analysed using Echo PA C v110.The STE analysis was performed offline by single experienceed to av- oid interobserver variability.RA endocardial border was manually traced in four-chamber view when the RA was at its minimum volume after contractio- n.The software automatically generated a region of interest(ROI)composing by six segments.If tracking of the RA endocardium was ungratified,manual adjustments of the shape and width of ROI were performed to acquire optimal tracking.As preciously described,RA peak atrial longitudinal strain(PALS), measured at the end of the reservoir phase,was calculated by averaging values observed in all RA segments(global RA PALS). RA strain rate(SR)was measu-red by quantifying RA endocardial velocities of contraction and relaxation and local deformation.SR was mearsured from the QRS onset and three different waves were analyzed.Results: 1 Comparision of general clinical parameters between controls and patie- nts with pulmonary hypertension Gender,age,body surface area and blood pressure did not significantly differ between controls and PH patients(P>0.05).Heart rate was significantly faster in PH patients than in controls(P<0.01),but there was no difference in the heart rate among PH patients with different WHO-FC(P>0.05). 2 Comparison of echocardiographic characteristics beween healthy cont- ols and patients with pulmonary hypertension When compared with control subjects,PH patients exhibited greater RA volume and RV volume(P<0.01),and similarly showed greater RA volume index and RV volume index adjusted by BSA(P<0.01).But there were no significant differences in any of the RA/RV indices between PH patients with WHO-FC Ⅲ and Ⅳ,and similar TAPSE in PH patients as compared with controls.RV fractional area change was lower in PH patients than in controls(P<0.01),but was similar in PH patients with WHO-FC II and III(P>0.05),and significantly reduced in PH patients with WHO-FC IV.RV subcostal wall thickness and RV myocardial performance index was greater in PH patients than in controls(P<0.01),but were similar between PH patients with adjacent WHO-FC(P>0.05). 3 Comparison of 2D-STE analysis between healthy controls and patients with pulmonary hypertension. RA PALS was significantly lower in PH patients than in controls(Figure 1),and gradually reduced with the development of cardiac insufficiency(P<0.01).RA systolic and early diastolic strain rates were significantly decrea- sed in PH patients in comparison with the controls(P<0.01).Similar relationsh- ips were obtained for global longitudinal strain of RV(P<0.01).The changes were not obvious in the early right heart failure,and were significantly reducedin advanced PH patients. 4 Correlations between RA PALS and functional capacity and other clini- cal parameters RA PALS significantly positive correlated with RV fractional area chang- e,Global longitudinal strain of RV and 6-minute walk distance(P<0.05); 6-minute walk distance significantly positive correlated with RA PALS(r=0.44, P<0.01)and negative with RA volume index(r=-0.431,P<0.01). 5 Parameters of the ROC curve analysis Compared with the functional class of patients,RA volume index had a sensitivity of 71.1% and a specificity of 92%(AUC0.827)in predicting functio- nal status with an increase of >37.55 in absolute value;and RA PALS had a se- nsitivity of 86.6% and a specificity of 84%(AUC0.979)in predicting functional status with a cut-off value of 38.08.Conclusion: RA deformation is significantly damaged in PH patients.RA reservoir fu- nction can be estimated using 2D-STE,and gradually decrease in PH patients with different World Health Organization-functional class(WHO-FC).RA PAL S is a powerful predictor of functional status and exercise capacity in PH patients.