Assessment Of Systolic Synchrony And Function Of Right Ventricle In Patients With Hypertrophic Cardiomyopathy

Objective: To evaluate synchronization of interventricular contraction and intra-right ventricular contraction using the Tissue Doppler Imaging (TDI) and to investigate right ventricular function in patients with hypertrophic cardiomyopathy (HCM).Methods: 33 cases of patients with hypertrophic cardiomyopathy (22 men, 11women, mean age 53.5±11.7y ) were selected as HCM group and 23 cases of healthy volunteers (men 11, women 12, mean age 60.1±12.1y ) were selected as control group. All participants underwent a transthoracic echocardiographic study including two-dimensional, color flow and pulse wave Tissue Doppler as well as tissue velocity imaging using a GE Vivid 7.0 ultrasound system (GE vivid 7.0) which equipped with an workstation available for TVI quantitation analysis. An ECG was simultaneously recorded and the images and data of the test were stored. With conventional two-dimensional echocardiography, end-diastolic thickness of interventricular septum (IVSd) and posterior left ventricular wall (LVPWd)were measured from parasternal long axis view. In addition, left ventricular ejection fraction (LVEF), right ventricular end-diastolic areas (RVEDA) and end-systolic areas (RVESA) were measured from the apical 4-chamber view. The right ventricular fractional area change (RVFAC) was calculated by the following formula: RVFAC(%)=(RVEDA-RVESA)/RVEDA. With pulse wave Tissue Doppler Imaging, the systolic (Sm), early (Em) and late (Am) diastolic annular velocities were measured at the left ventricular lateral wall (LVW), interventricular septum (IVS) and right ventricular lateral free wall (RVW) from the apical four-chamber view. Region of interest was placed at RVW to measure isovolumic contraction time (IVCT), isovolumic relaxation time (IVRT) and ejection time (ET). Myocardial performance index (TEI) was calculated by the following formula: TEI=IVCT+IVRT/ ET. With Tissue Velocity Imaging (TVI), regions of interest were placed at right ventricular lateral free wall (RVW) and left ventricular lateral wall (LVW) to measure the time-to-peak (TTP) of systolic velocity from the onset of Q-wave on the electrocardiogram to calculate time difference between RVW and LVW ; regions of interest were placed at the basal and middle segments of the RVW to measure the time-to-peak (TTP) of systolic velocity from the onset of Q-wave on the electrocardiogram to calculate time difference between the basal and middle segments.Results:1. Compared with control group, the following parameters in HCM group increased significantly respectively: IVSd (9.0±1.5mm vs 19.0±4.1mm, P<0.01), LVPWd (9.5±1.0mm vs 11.5±1.5mm, P<0.01) .2. Compared with control group, myocardial performance index (TEI) of RVW in HCM group increased significantly (0.5±0.1 vs 0.7±0.3, P<0.01).3. Compared with control group, the following parameters in HCM group decreased significantly respectively ( P<0.01): the Sm, Em and Am of LVW and IVS; Furthermore, the Em of RVW decreased significantly (P<0.01).4. Compared with control group, the TTP of LVW, IVS, RVW at the annulus and the TTP of RVW at basal and middle segments in HCM group delayed significantly respectively ( P<0.01).Compared with control group, the time difference of mechanical activation between RVW and LVW in HCM group increased significantly (18.7±7.6ms vs 50.3±38.6ms, P<0.01), which showed the interventricular dyssynchrony existed; the time difference of mechanical activation between RVW and IVS in HCM group increased significantly(16.1±7.2ms vs 39.1±49.7ms, P<0.05),the time difference of mechanical activation between basal and middle segments of the RVW in HCM group increased significantly (0±2ms vs 22±42ms, P<0.01), which showed the intra-right ventricular dyssynchrony existed.5. Compared with non-obstructive hypertrophic cardiomyopathy group, the time difference of mechanical activation between RVW and LVW in hypertrophic obstructive cardiomyopathy group increased significantly (37.1±24.6ms vs 85.6±48.0ms, P<0.01). No significant difference were found between hypertrophic obstructive cardiomyopathy group and non-obstructive hypertrophic cardiomyopathy group, in right ventricular systolic function and intra-right ventricular dyssynchrony.Conlusion: Significant interventricular and intra-right ventricular dyssynchrony and right ventricular diastolic dysfunction were found in a small group of patients with hypertrophic cardiomyopathy, compared with control group. In Hypertrophic obstructive cardiomyopathy, interventricular ventricular dyssynchrony was more significant than that in non-obstructive hypertrophic cardiomyopathy; no significant difference were found between hypertrophic obstructive cardiomyopathy group and non-obstructive hypertrophic cardiomyopathy group, in right ventricular systolic function and intra-right ventricular dyssynchrony.