The Clinical Application Of Echocardiographic Techniques In Cardiac Resynchronization Therapy

Part I: The mechanical dyssynchrony assessed by echocardiography in patients with congestive heart failure and intra-ventricular conduction delayObjectives:1. To assess the ventricular mechanical dyssynchrony in patients with congestive heart failure and intra-ventricular conduction delay by conventional echocardiography and tissue Doppler imaging and to investigate the correlation between the QRS duration and mechanical dyssynchrony.2. To investigate if the types of intra-ventricular conduction delay were related to mechanical dyssynchrony.Methods:We studied 93 chronic heart failure patients. The inclusion criteria included: NYHA FCⅢ-Ⅳ, QRS duration > 120ms, LVEF<40%, Patients with atrial fibrillation were excluded. All the patients underwent conventional echocardiography and tissue Doppler imaging. The left ventricular pre-ejection time (LVPT) was measured from the onset of QRS to the beginning of aortic flow. The right ventricular pre-ejection time (RVPT) was measured from the onset of QRS to the beginning of pulmonary flow. The inter-ventricular systolic delay was calculated as LVPT-RVPT. The interval between QRS onset and peak systolic velocity was measured from the myocardial velocity curves in 12 standard basal and middle segments, and the standard deviation (Ts-SD) was used as a measure of intra-ventricular dyssynchrony. Patients with CLBBB, CRBBB and intra-ventricular conduction delay without bundle branch block were compared.Results:1. The LVPT was > 140ms in 80% of patients with CLBBB and the Ts-SD was >32.6ms in 80% patients. 2. In patients with congestive heart failure and CLBBB, the LVPT correlated significantly with QRS duration(r=0.56, p<0.01). When patients were divided into two groups, one with QRS duration > 160ms(group A) and one with QRS≤160ms>120ms(group B), the LVPT was significantly higher in group A than group B. However, the tissue Doppler-derived parameters Ts-SD,Ts-12 and Ts-sep-lat did not show significant difference between two groups.3. In patients with heart failure and CRBBB, 55% had intra-ventricular dyssynchrony as defined by Ts-SD >32.6ms.4. When the QRS duration was comparable in each group, the septal to posterior wall motion delay, LVPT, LVPT-RVPT and Ts-SD were all significantly higher in patients with CLBBB than CRBBB. Only LVPT was significantly higher in patients with CLBBB compared with patients with intra-ventricular conduction delay without bundle branch block.Conclusions:1. In patients with congestive heart failure and CLBBB, the QRS duration correlated significantly with left ventricular pre-ejection delay, but not intra-ventricular dyssynchrony.2. The type of intra-ventricular conduction delay correlated with mechanical dyssynchrony. Part II: The Pattern of Dyssynchrony is Different in an Ischemic Cardiomyopathy Population vs. NonischemicsBackground:The lateral and posterior walls are generally thought as the most prevalent sites of greatest delay in patients with heart failure. In more than one-third of cases the most delayed wall is located at another site. We therefore investigated if the pattern of wall motion delay is related to whether the etiology is ischemic.Methods:We studied 74 normal subjects (age 40±14 years, 66% men), 48 nonischemic cardiomyopathy patients (age 55±12 years, 63% men, QRS duration 148ms, 52% CLBBB, LVEF 29%) and 43 ischemic cardiomyopathy patients (age 55±12 years, 64% men, QRS duration 157ms, 45% CLBBB, LVEF 31%) who underwent echo with color tissue Doppler imaging. The interval between QRS onset and peak systolic velocity was measured from the myocardial velocity curves in 12 standard basal and middle segments, and the standard deviation (Ts-SD) was used as a measure of intraventricular dyssynchrony. The Ts among different segments were compared in each group of patients.Results:The Ts-SD in normal subjects, nonischemic cardiomyopathy and ischemic cardiomyopathy patients are 22.7±10.5ms, 45.3±15.6ms and 45.5±17.0ms respectively. In normal subjects, the Ts of the inferior wall and posterior septum are significantly longer than that of lateral wall and anterior wall (respectively 154.0±34.2ms, 151.1±32.3ms Vs 129.6±29.0ms, 124.9±24.9; p<0.05). The values of posterior walls and anterior septal segments are in the middle. In patients with heart failure the Ts of each segment is prolonged compared with normal subjects. In the nonischemic cardiomyopathy patients the Ts of the inferior wall is most delayed, and is significantly longer than the lateral wall, anterior septum and the anterior wall (respectively 244.2±60.9ms Vs 208.5±68.1ms, 199.1±49.7ms, 192.6±52.2ms; p<0.05). In the ischemic cardiomyopathy patients, although the increased Ts-SD indicated marked intraventricular dyssynchrony, we found no significant differences of Ts among the lateral wall, the inferior wall and the posterior wall which may be due to the heterogeneous patterns of regional wall motion delay in the ischemic cardiomyopathy patients.Conclusion:The pattern of wall motion delay is less predictable and more variable in an ischemic cardiomyopathy population than in a nonischemic group. Part III: The Effect of Cardiac Resynchronization Therapy in Patients with Congestive Heart FailureObjectives:The effects of cardiac resynchronization therapy (CRT) were evaluated in patients with congestive heart failure in our centers and the potential reasons for nonresponders were investigated.Methods:Fifty three patients with congestive heart failure who received CRT were enrolled. Conventional echocardiography and tissue Doppler imaging were carried out in each patient before implantation and during 6 month follow-up. Fifteen patients completed follow-up at 1 week, 1 month, 3 month and 6 month. Clinical response was defined as an increase of one NYHA functional class and echocardiographic response was defined as a reduction in LV end-systolic volume by >15% or an increase of absolute value of LVEF>5%.Results:1. The clinical response rate was 75% and echocardiographic response rate was 68.5% during 6 month follow-up.2. Six months after CRT, the LVEDV and LVESV decreased from 210.6±96.5ml and 159.3±83.1ml to 171±89.1ml and 109.0±68.5ml respectively. The LVEF increased significantly from 27.4±6.7% to 40.4±10% (p<0.01 ).The dimension of left atria also decreased (p<0.05). The mitral regurgitation grade decreased from 2.7±1.0 to 2.1±1.0. Pulmonary systolic pressure decreased significantly from 49.6±13.6mmHg to 38.7±14.5mmHg.3. CRT immediately increased LVEF and GSCA (P<0.01). Moreover, LVPT-RVPT and Ts-SD decreased significantly (P<0.01 and P<0.05, respectively). The Tei index, left ventricular diastolic filling time, Tdis-SD and Tdis-MAX also improved significantly. Six months of CRT further improved LVEF and GSCA (P<0.05) , and a significant reverse left ventricular remodeling was observed. The Tei index, left ventricular diastolic filling time, interventricular dyssynchrony and intraventricular dyssynchrony did not changed significantly. 4. The response rate for patients with atrial fibrillation was only 45%, which was significantly lower than that for patients with sinus rhythm.5. QRS duration, pulmonary systolic pressure and LVPT were significantly higher in responders than nonresponders, whereas no significant difference was seen in LVEF, left ventricular volume and NYHA functional class between the two groups.Conclusions:1. CRT was associated with the improvement of left ventricular function and dyssynchrony in selected heart failure patients. Furthermore, the degree of mitral regurgitation and pulmonary pressure was reduced after CRT.2. CRT could immediately improve left ventricular performance and ventricular dyssynchrony. Six months of pacing further improves left ventricular performance and remodeling. While the interventricular and intraventricular dyssynchrony do not change.3. The response rate in patients with atrial fibrillation was not as good as sinus rhythm. The AV node ablation or atrial fibrillation defibrillation might be needed to improve the effect of CRT.4. When tissue Doppler dyssynchrony parameter was used as the inclusion criteria of CRT, QRS duration, LVPT and pulmonary systolic pressure was able to predict the response to CRT. Part IV: Two dimensional Longitudinal speckle tracking imaging is superior to tissue Doppler imaging in predicting the echocardiographic response to cardiac resynchronization therapyObjectives:Two dimensional longitudinal speckle tracking strain and strain rate imaging is a new echocardiographic method which could be used to assess dyssynchrony and regional contractility. Therefore, the aims of the study were to evaluate the ability of speckle tracking strain and strain rate imaging to predict the echocardiographic response to CRT, and to compare it with tissue Doppler imaging.Methods:Fifty-three heart failure patients who received CRT and were followed up for more than 6 months were analyzed. TDI and two dimensional speckle tracking imaging in addition to standard echocardiography was performed before CRT. Standard echocardiography was performed 6 months after CRT. The mean age of the 50 patients was 69±12 years.Results:1. Baseline conventional echocardiographic characteristics were comparable in responders and nonresponders to CRT, except for LV pre-ejection time, which was longer in responders.2. Baseline tissue Doppler characteristics were unable to predict the echocardiographic response.3. Baseline global longitudinal strain were unable to predict the echocardiographic response, whereas the sum of reversal longitudinal strain showed a sensitivity of 68% and specificity of 76% for the defined echocardiographic response using a cutoff value of 9.7%.4. Dyssynchrony parameters assessed by two dimensional longitudinal strain rate imaging as well as the transverse displacement were significantly higher in responders than nonresponders. Tsr-SD provided a sensitivity of 73% and specificity of 65% with a cutoff value of 70.7ms, for prediction of the defined echocardiographic response. Conclusions:Two dimensional Longitudinal speckle tracking imaging is superior to tissue Doppler imaging in predicting the echocardiographic response to cardiac resynchronization therapy. Part V: Optimal pacing site selection of left ventricle for cardiac Resynchronization therapy by tissue Doppler imagingBackground:Cardiac resynchronization therapy (CRT) has become one of the major treatments for symptomatic heart failure patients with intra-ventricular conduction delay. Preliminary reports suggest that optimal lead positioning plays an important role in the outcome of cardiac resynchronization therapy. Data suggests that the lateral or posterolateral location is ideal, given that these are the sites of greatest contractile delay. However, tissue Doppler imaging study showed heterogeneous patterns of regional wall motion delay. More recently, some studies have shown that the scar density adjacent to the LV lead might affect the effect of CRT.Objectives:The aims of the study were to investigate whether the assessment of the most delayed site by tissue Doppler imaging might be of an optimal left ventricular (LV) lead position for improved effectiveness of CRT in patients with nonischemic cardiomyopathy.Methods:In 33 patients with advanced nonischemic heart failure, the most delayed site was defined by tissue Doppler imaging as the interval between the onset of QRS and the peak systolic velocity. The left ventricular pacing site was considered concordant with the most delayed site when the LV lead was inserted at the wall with the greatest delay assessed by tissue Doppler imaging. After CRT, patients were divided into group A (20/33) (i.e., paced at the most delayed site) and group B (13/33) (i.e., paced at any other site).Results:After CRT, in all patients LV end-diastolic volume(LVEDV) and end-systolic volume(LVESV) decreased (p< 0.01), LV ejection fraction (LVEF) increased (p < 0.002), New York Heart Association class decreased (p<0.01). Group A showed greater improvement over group B in LVESV (p< 0.05) and LVEF (p< 0.05).Conclusions:In patients with nonischemic cardiomyopathy, CRT significantly improved LV performance; however, the greatest improvement was found in patients paced at the most delayed site.