Assessment of right ventricular function using echocardiographic speckle tracking of the tricuspid annular motion: comparison with cardiac magnetic resonance

Background: Assessment of right ventricular (RV) function is difficult due to the complex shape of this chamber. Tricuspid annular plane systolic excursion (TAPSE) measured with M-mode echocardiography is frequently used as an index of RV function. However, its accuracy may be limited by ultrasound beam misalignment. We hypothesized that two-dimensional (2D) speckle tracking echocardiography (STE) could provide more accurate estimates of RV function. Accordingly, STE was used to quantify tricuspid annular displacement (TAD), from which RV longitudinal shortening fraction (LSF) was calculated. These STE derived indices were compared side-by-side with M-mode TAPSE measurements against cardiac magnetic resonance (CMR) derived RV ejection fraction (EF). Methods: Echocardiography (Philips iE33, four-chamber view) and CMR (Siemens, 1.5 T) were performed on the same day in 63 patients with a wide range of RV EF (23–70% by CMR). TAPSE was measured using M-mode echocardiography. TAD and RV LSF were obtained using STE analysis (QLAB CMQ, Philips). TAPSE, TAD and RV LSF values were compared with RV EF obtained from CMR short axis stacks. Results: STE analysis required <15 seconds and was able to track tricuspid annular motion in all patients as verified visually. Correlation between RV EF and TAD (0.61 free-wall, 0.65 septal) was similar to that with M-mode TAPSE (0.63). However, STE-derived RV LSF showed a higher correlation with CMR EF (r = 0.78). Conclusion: RV LSF measurement by STE is fast and easy to obtain and provides more accurate evaluation of RV EF than the traditional M-mode TAPSE technique, when compared to CMR reference. (Echocardiography 2012;29:19-24)     

A theoretical and experimental model of ventricular interdependence

Summary Because of the close anatomical association between the ventricles, the volume of one ventricle can directly affect the volume and pressure within the other ventricle. To study the mechanical coupling between the ventricles, we modeled the right and left ventricles as a two-compartment model with right wall (C_iw), septal (C_s), and left wall (C_lw) compliances. Based on the balances of forces across the septum, four equations were obtained to predict the transfer of pressure (P) and volume (V) information from one ventricle to another. The validity of the theoretical analysis was tested first in a physical model and then in a post-mortem heart preparation. The standard errors of estimate comparing the predicted to measured values were low for both the physical model and the post-mortem heart data. All values were significantly related (P<0.05) with r>0.89. The results show excellent correlation between predicted and measured values. This model provides a better understanding of ventricular interdependence and may help to predict effects of hypertrophy and/or myocardial ischemia on ventricular interdependence.This study was supported in part by PHS NIH Grant Nos. HL31644 and HL22843. Dr. Santamore is a recipient of an NIH Research Carrer Development Award No. H101026     

斑点追踪技术评价左室扭转及解旋运动的临床应用

近几年,斑点追踪技术在国内已初步应用于临床,且取得了一定的成果,如评价心功能、心脏再同步化治疗及起搏治疗前后指导以及冠心病、心肌病、瓣膜性心脏病等疾病的诊断与治疗效果。本文从上述几方面做一综述,以促进其在临床工作中的进一步应用及发展。     

Quantitative assessment of left ventricular volume and ejection fraction using two-dimensional speckle tracking echocardiography

Aims: Two-dimensional speckle tracking echocardiography (2DSTE) allowsmeasurements of left ventricular (LV) volumes and LV ejectionfraction (LVEF) without manual tracings. Our goal was to determinethe accuracy of 2DSTE against real-time 3D echocardiography(RT3DE) and against cardiac magnetic resonance (CMR) imaging. Methods and results: In Protocol 1, 2DSTE data in the apical four-chamber view (iE33,Philips) and CMR images (Philips 1.5T scanner) were obtainedin 20 patients. The 2DSTE data were analysed using custom software,which automatically performed speckle tracking analysis throughoutthe cardiac cycle. LV volume curves were generated using thesingle-plane Simpson's formula, from which end-diastolic volume(LVEDV), end-systolic volume (LVESV), and LVEF were calculated.In Protocol 2, the 2DSTE and RT3DE data were acquired in 181subjects. RT3DE data sets were acquired, and LV volumes andLVEF were measured using QLab software (Philips). In Protocol1, excellent correlations were noted between the methods forLVEDV (r = 0.95), ESV (r = 0.95), and LVEF (r = 0.88). In Protocol2, LV volume waveforms suitable for analysis were obtained from2DSTE images in all subjects. The time required for analysiswas <2 min per patient. Excellent correlations were notedbetween the methods for LVEDV (r = 0.95), ESV (r = 0.97), andLVEF (r = 0.92). However, 2DSTE significantly underestimatedLVEDV, resulting in a mean of 8% underestimation in LVEF. Intra-and inter-observer variabilities of 2DSTE were 7 and 9% in LVvolume and 6 and 8% in LVEF, respectively. Conclusions: Two-dimensional speckle tracking echocardiography measurementsresulted in a small but significant underestimation of LVEDVand EF compared with RT3DE. However, the accuracy, low intra-and inter-observer variabilities and speed of analysis make2DSTE a potentially useful modality for LV functional assessmentin the routine clinical setting.     

右室流出道间隔部与心尖部起搏对心功能的影响

目的了解右室流出道间隔部起搏和右室心尖部起搏参数的差异及对心功能的影响。方法65例安装DDD起搏器的患者随机分为右室心尖部（RVA）与右室流出道间隔部（RVS）起搏进行置入时及术后3个月起搏参数、左室射血分数的分析。结果两组基线资料无显著差异，术后15min及3个月两组的起搏阂值、感知、阻抗均无差异，术后3个月右室流出道间隔部组左室射血分数显著高于右室心尖部组（0．57±0．04vs0．50±0．03，p〈0．05）。结论右室流出道间隔部起搏安全可行，且对心功能的影响优于右室心尖部起搏。     

Physiologic determinants of left ventricular systolic torsion assessed by speckle tracking echocardiography in healthy subjects

Background: The associations of left ventricular (LV) systolic torsion with clinical and echocardiographic variables in physiological conditions have not been fully investigated. We explored the independent determinants of LV systolic torsion in a population of normal subjects. Methods: In 119 healthy subjects, peak twist angle (LVtw) and torsion (LVtor) during ejection, and the QRS‐LVtw interval (time‐to‐peak LVtw) were measured by speckle tracking. LV twisting rate and rotational deformation delay were also determined. Results: Stepwise multiple regression showed that LVtw was independently associated with indexed end‐systolic volume (β=–0.200, P < 0.0001), peak early diastolic mitral annulus velocity (β=–0.186, P = 0.0001), heart rate (β= 0.178, P = 0.0003), and male gender (β=–0.174, P = 0.0004). Similar results were found for LVtor. Age was the only parameter, which has demonstrated an independent correlation with time‐to‐peak LVtw (β= 0.329, P < 0.0001). Despite significance of these associations, the proportions of variability explained by regression models were relatively low (range 11–26%), and no accurate predictive models were identifiable for LV twisting rate and rotational deformation delay. Conclusion: In normal individuals, indexed end‐systolic LV volume, LV relaxation, heart rate, gender, and age correlate independently with LV torsion mechanics. However, conventional echocardiographic and clinical variables are not able to predict LV torsion mechanics. (Echocardiography 2011;28:641‐648)     

二维超声斑点追踪显像技术对正常人左室旋转和扭转运动的评价

目的:应用二维超声斑点追踪显像技术探讨正常人左室旋转(LVrot)和左室扭转(LVtw)运动特征。方法:入选健康成人志愿者58例,取胸骨旁左室心尖和心底短轴观对LVrot进行定量分析,获LVrot及LVtw角度随心动周期变化曲线,记录心底部与心尖部LVrot角度峰值和LVtw角度峰值及达峰时间。结果:正常人扭转运动主要表现为心底部顺时针旋转和心尖部逆时针旋转,心脏整体表现为心动周期内逆时针方向为主的扭转运动。心尖部和心底部旋转角度达峰时间差异无统计学意义(P>0.05)。扭转角度于收缩末期达峰值。结论:应用二维超声斑点追踪显像技术可无创性评价正常人LVrot和LVtw运动特征。左室心底部及心尖部旋转角度、达峰时间可做为评价左室运动同步性指标之一。     

Acute alterations in systolic ventricular interdependence—mechanical dependence of right ventricle on left ventricle following acute alteration of right ventricular free wall

Summary The purpose of the study was to examine whether systolic ventricular interdependence can be acutely altered by changes in the mechanical properties of the ventricular wall. In eight acute canine studies, we released an aortic constriction during diastole. We measured right ventricular (RV) pressure changes (dPr) caused by sudden changes in left ventricular (LV) pressure (dPl). Measurements were obtained during control, 10 min after right coronary artery occlusion, and then 15 min after injecting glutaraldehyde into the RV free wall. By superimposing the pressure tracings of the beats immediately before and after the aortic release, the instantaneous pressure difference ratio (dPr/dPl) was calculated during systole. Maximal value of the pressure difference ratio decreased from control 0.11±0.04 to ischemia 0.08±0.03; (p<0.05) and increased with glutaraldehyde 0.15±0.06; (p<0.05). Thus, acute ischemia in RV free wall decreased the magnitude of systolic ventricular interdependence from LV to RV, while glutaraldehyde, which stiffens the RV free wall, increased the magnitude.This study was supported in part by NIH grant number HL36068     

Circadian blood pressure pattern and right ventricular and right atrial mechanics: A two- and three-dimensional echocardiographic study

The purpose of this investigation was to evaluate right ventricular (RV) and right atrial (RA) function and mechanics in untreated hypertensive patients with different blood pressure (BP) patterns by using two-dimensional (2DE) speckle tracking analyses and three-dimensional echocardiography (3DE). This cross-sectional study included 174 recently diagnosed hypertensive patients. All patients underwent a 24-hour ambulatory BP monitoring and complete 2DE and 3DE examination, including 2DE speckle tracking analysis. Our results showed that 2DE RV global longitudinal strain was significantly lower in the non-dippers. Similar results were obtained for 2DE RV systolic and early diastolic strain rate. The RA longitudinal strain, as well as RA systolic and early diastolic strain rate, was decreased in non-dippers. Our results revealed that 3DE RV end-diastolic and end-systolic volumes were increased, whereas 3DE RV ejection fraction was reduced in non-dipper hypertensive patients. Similar results were obtained for RA volumes and RA ejection fraction estimated by 2DE. Independent predictors of 3DE RV ejection fraction, 2DE RV and RA global longitudinal strain were left ventricular mass index and RV wall thickness. An additional independent predictor of the RV longitudinal strain was 3DE RV ejection fraction, and for RA longitudinal strain, an additional independent predictor was tricuspid E/é ratio. Two-DE speckle tracking evaluation and 3DE examination revealed that the RV and RA function and mechanics were more deteriorated in the non-dipper patients than in dipper untreated hypertensive patients.     

Reduced and delayed untwisting of the left ventricle in patients with hypertension and left ventricular hypertrophy: a study using two-dimensional speckle tracking imaging.

AIMS: Newly developed two-dimensional ultrasound speckle tracking imaging allows measurements of left ventricular (LV) rotation and twist. Because LV untwisting predominantly occurs during the isovolumic relaxation period, its assessment reflects the process of LV relaxation. The aim of this study was to examine whether LV hypertrophy (LVH) adversely affects LV untwisting and abnormalities in LV untwisting could become a novel marker in assessing LV relaxation abnormalities. METHODS AND RESULTS: We acquired basal and apical LV short-axis images in 49 hypertensive patients. Using two-dimensional strain software, a time-domain speckle tracking was performed, and the mean value of LV rotation was obtained at each plane. LV twist was defined as apical rotation relative to the base. In order to adjust for inter-subject differences in heart rate, the time sequence was normalized to the percentage of systolic and diastolic duration. The degree of LV untwisting was calculated as the percentage of systolic twist : untwisting = (TwistES-Twistt/TwistES) x 100, where Twistt is twist at time t and TwistES is twist at end-systole. Although peak systolic twist was not different, early diastolic LV untwisting and untwisting rate during isovolumic relaxation period was significantly delayed and reduced in parallel to the severity of LVH, as assessed by LV mass index. CONCLUSION: The observed delayed and reduced diastolic untwisting during the isovolumic relaxation period noted in hypertensive patients with LVH may contribute towards the LV relaxation abnormality. Two-dimensional speckle tracking imaging is a novel tool which can be used for the non-invasive assessment of LV relaxation.     

An echocardiographic study of right and left ventricular adaptation to physical exercise in elite female orienteers.

BACKGROUND: A considerable body of echocardiographic studies has described how athletic training induces morphological adaptation of the left ventricle in male endurance athletes, but only a few studies have described left ventricular adaptation in female endurance athletes. In contrast to changes in the left ventricle far less attention has been directed towards right ventricular changes due to extensive physical exercise. The purpose of this study was to obtain normal values and to determine if there are any differences in right and left ventricular cavity and wall dimensions between female orienteers and females with a mainly sedentary lifestyle. METHODS: Echocardiography was performed in 42 highly trained elite female orienteers and 32 healthy female students with a predominantly sedentary lifestyle. The 74 females had no history of cardiac disease, a normal electrocardiogram and showed no echocardiographic abnormalities. M-mode and two-dimensional measurements of the right and left ventricular cavity and wall were obtained in elite orienteers and sedentary females. For the right ventricle and wall, multiple cross-sections were used and measurements were obtained from the right ventricular inflow and outflow tract. RESULTS: The left ventricular end-diastolic cavity dimension and the left ventricular wall thickness were significantly greater in the athletes compared with the sedentary controls. The right ventricular inflow tract measurements were all significantly greater in the orienteers compared with the controls but the right ventricular outflow tract measurements were comparable in the study groups. The right ventricular wall thickness, calculated as the mean of three different wall measurements was an average of 13% greater in the athletes compared with the sedentary controls. CONCLUSION: This study suggests symmetrical cardiac enlargement with a concomitant increase in both the right and left ventricular wall, probably reflecting the increased haemodynamic loading in the female athletes.     

斑点追踪技术评价心肌梗死患者冠脉内支架术前后 左心室收缩功能变化

目的 探讨斑点追踪成像技术（speckle tracking imaging,STI）评价心肌梗死患者冠脉内支架置入术（percutaneous coronary intervention,PCI）前后左心室收缩功能的应用价值。方法 病例组选取30例心肌梗死拟行冠脉内支架术的患者,正常对照组选取35例健康人。对正常对照组及接受PCI治疗的患者在术前、术后一周、1个月、3个月、6个月时进行常规超声心动图检查和斑点追踪成像分析,测量出左室壁上的各个心肌节段在纵向、径向、圆周方向三方面的应变峰值(LS、RS、CS),比较分析各参数在PCI术前后的变化。结果：与正常对照组比较,病例组PCI治疗前后左室LVDd、LVESV、LVEDV 较对照组扩大,LVEF 比对照组降低,变化均有统计学意义(P均<0.05);与 PCI治疗前比较,PCI 术后 1周 、1个月 LVDd、LVESV、LVEDV 及 LVEF 都没有明显改变,变化无统计学意义(P 均<0.05);PCI 治疗后3个月、6个月时 LVDd、LVESV、LVEDV 比 PCI 治疗前及 PCI 治疗后1个月都有一定的缩小,LVEF 增高,变化均有统计学意义(P 均<0.05)。病例组术后1周LS、RS、CS均较术前无明显改善（P>0.05）;病例组PCI术后1个月与术前比较LS测值明显改善的有11个节段,RS测值明显改善的有9个节段,CS测值明显改善的有12个节段;PCI术后3个月患者相应缺血节段心肌LS、RS、CS较术后1个月比较有所改善,但部分节段二维应变值与术后 1个月组比较差异无统计学意义（P＞0.05）;PCI治疗后6个月各缺血节段较术前及术后 1个月均有显著改善（P<0.05）。