QRS width does not reflect ventricular dyssynchrony in patients with heart failure

The purpose of this study was to evaluate QRS width as an indication for cardiac resynchronization therapy. This study group consisted of 64 heart failure patients (51 men, age average 60.5 ± 15.5 years) with a left ventricular ejection fraction (LVEF) of less than 35%. Patients were divided into two groups according to their QRS width; the wide QRS group (QRS width greater than or equal to 120 ms, 31 patients) and the narrow QRS group (QRS width less than 120 ms, 33 patients). The ventricular dyssynchrony (VD), i.e., the inter- and intraventricular dyssynchrony, of the two groups was compared. The correlation between QRS width and VD was evaluated in all patients. There were no significant differences between the wide and the narrow QRS groups concerning interventricular dyssynchrony [28.4 ± 26.1 ms vs. 25.3 ± 18.2 ms, not significant (NS)] or intraventricular dyssynchrony (99.0 ± 43.8 ms vs. 109.0 ± 56.6 ms, NS). Nor were there any differences in the LVEF (26.6 ± 6.6% vs. 28.2 ± 5.1%, NS), brain natriuretic peptide (BNP) (567.0 ± 319.0 pg/ml vs. 390.0 ± 375.8 pg/ml, NS), and New York Heart Association (NYHA) class (2.4 ± 0.8 vs. 2.0 ± 1.0, NS). QRS width did not correlate with interventricular (r = 0.026, NS) or intraventricular dyssynchrony (r = 0.052, NS). There were no differences in VD between the two groups based on differences in QRS width. There was also no correlation between QRS width and VD. It is suggested that QRS width is not an absolute indication for cardiac resynchronization therapy.     

实时三维超声心动图评价心力衰竭患者左室重构与收缩同步性的临床研究

目的应用实时三维超声心动图(RT-3DE)分析评价不同程度心力衰竭(HF)患者左室重构指数(LVRI)与收缩不同步参数。方法随机收集80例各种病因所致HF患者和32例正常人,HF患者根据严重程度分为A、B、C 3组。均给予RT-3DE检查并获取下列参数:左室舒张末容积(LVEDV)、左室收缩末容积(LVESV)及左室舒张末期质量(LVM)、左室重构指数(LVRI)。收缩不同步参数包括:①各节段达到收缩期收缩峰值的平均时间(平均3D-Ts);②心率校正后16节段收缩期不同步峰值的标准差(Tmsv-16sd/RR,SDI);③16节段收缩达最小容积时间的最大时间差(Tmsv16-dif)。比较各组间参数差异及LVRI与不同步参数的相关性。结果与对照组相比,HF各组随程度加重所有参数均呈上升趋势,尤以中重度B、C两组显著。相关性分析显示,HF各组LVRI与不同步参数均呈正相关,在重度HF C组,LVRI与平均3D-Ts、SDI呈显著正相关,相关系数分别为:0.76,0.82。结论 HF患者可出现不同程度的左室重构及收缩不同步,LVRI与收缩不同步呈明显相关,且相关性随心力衰竭程度加重呈升高趋势。LVRI在一定程度上可以反映左室收缩的不同步情况。     

应用实时三维超声心动图评价不同程度左室射血分数减低者的左室收缩同步性

目的 应用实时三维超声心动图分析左室不同步性在不同程度左室射血分数(LVEF)减低者中的发生率.方法 对64例LVEF减低者的实时三维超声心动图时间-容积进行比较分析,其中LVEF<30%者35例,30%≤LVEF<45%者29例.以收缩期不同步化指数(SDI)>8.3%作为室内收缩不同步的指标.结果 30%≤LVEF<45%者中有20.7%存在收缩不同步,而LVEF<30%者中不同步比例高达63.9%,二者差异有统计学意义(P<0.01).16节段、12节段(中间段和基底段)和6节段(基底段)最小收缩容积点时间的标准差和最大差值差异有统计学意义,P均<0.01.30%≤LVEF<45%者平均收缩期不同步化指数为(6.4-2.3)%.LVEF<30%患者为(4.5-6.5)%(P<0.001).收缩期不同步化指数与左室收缩功能有良好的相关性,与左室射血分数相关系数r:0.493,P<0.001,与QRS间期不相关.结论 尽管30%≤LVEF<45%者的左室收缩同步比例很高,但仍有一定比例的患者存在收缩不同步.同时,亦有一定比例的LVEF<30%者同步性尚好.     

Poor agreement of echographic measures of ventricular dyssynchrony.

Echocardiography is playing an increasing role in patient selection for cardiac resychronization therapy (CRT). The most frequently used techniques for evaluating inter- and intraventricular dyssynchrony are standard echocardiography and tissue Doppler imaging (TDI). Whether these techniques give concordant results is unknown. We studied 44 patients with a left ventricular ejection fraction of Dyssynchrony was evaluated by standard echocardiography using the techniques described in the CARE-HF trial (interventricular mechanical delay and delayed motion of the posterior wall). Dyssynchrony was also measured by pulsed-wave TDI using delay to onset (Sm(o)) as well as to peak (Sm(p)) sustained systolic motion of the right ventricular free wall and of 4 basal segments of the left ventricle. A control group of 40 subjects with normal systolic function was studied for determining cutoff values. Agreement between standard echocardiography and TDI was poor for diagnosing inter- and intraventricular dyssynchrony (kappa < 0.33 for all comparisons). None of the patients had evidence of intraventricular dyssynchrony when evaluated for delayed posterior wall motion, whereas dyssynchrony was seen in 15/44 (34%, p = 0.001) patients using left ventricular dispersion of Sm(o) > 20 ms. Parameters using Sm(p) were highly variable with poor reproducibility, making them unsuitable for evaluating dyssynchrony. In conclusion, our study indicates that there is poor agreement between standard echocardiography and TDI for diagnosing dyssynchrony.     

Evaluation of Right Ventricular Contraction by Myocardial Strain in Children Using a Two-Dimensional Tissue Tracking Method

Two-dimensional tissue tracking makes it possible to detect myocardial strain in any direction. Consequently, this method is applicable for evaluation of myocardial dyssynchrony. This study enrolled 22 healthy volunteers (11 boys and 11 girls) ages 1.6 to 10.8 years (mean, 6.8 years). Echocardiography (subxiphoid right anterior oblique view) of the right ventricle was examined. Three tracking points were put on the right ventricle, and time-strain curves of the inflow tract (strain at the inlet) and the outflow tract (strain at the outlet) as well as time-strain curve of the pulmonary annulus diameter were made. The strain at the inlet was larger than the strain at the outlet (0.31 vs 0.15; p = 0.0003). The time to peak negative strain at the inlet was longer than at the outlet (0.48 vs 0.42 s; p = 0.001). The diameter of the pulmonary annulus shortened in systole, and the time to peak negative strain of the pulmonary annulus was longer than that of the outlet (0.48 vs 0.42; p = 0.001). There was no significant difference in the times between the pulmonary annulus and the inlet (0.48 vs 0.48; p = 0.78). Two-dimensional tissue tracking allows assessment for quantification of myocardial performance and timing of the right ventricle.     

Minimizing right ventricular pacing in sinus node disease: Sometimes the cure is worse than the disease

Traditional right ventricular(RV) apical pacing has been associated with heart failure, atrial fibrillation and increased mortality. To avoid the negative consequences of RV apical pacing different strategies have been developed, among these a series of pacing algorithms designed to minimize RV pacing. These functions are particularly useful when there is not the need for continuous RV pacing: intermittent atrioventricular blocks and, mainly, sinus node disease. However, in order to avoid RV pacing, the operationalfeatures of these algorithms may lead to adverse(often under-appreciated) consequences in some patients. We describe a case of a patient with sinus node disease, in whom right atrial only pacing involved long atrio-ventricular delay to allow intrinsic ventricular conduction, which led to symptomatic hypotension that could be overcome only by "forcing" also right ventricular apical pacing. We subsequently discuss this case in the context of current available literature.