Two-dimensional Speckle Strain and Dyssynchrony in Single Left Ventricles Vs. Normal Left Ventricles

Background. Patients with single left ventricle (LV) physiology maybe at increased risk for myocardial dysfunction and mechanical dyssynchrony. Newer echocardiographic modalities may be able to better quantitate LV function in this unique population. Our objective was to use 2D-speckle analysis of strain and strain rate to quantify systolic function and dyssynchrony in single LV post-Fontan patients and compare them to control LV patients. Methods. Patients with single LV status post-Fontan procedure and patients with normal biventricular anatomy were studied. Two-dimensional speckle echocardiography was used to measure strain, strain rate, time to peak, and longitudinal displacement in a six-segment model of the LV. Independent t-tests were used to compare group means. Results. Twelve patients with single LV physiology and thirteen control patients were studied. There was no significant difference in ages for the single LV patients vs. control patients (7.1 + 2.8 years vs. 5.7 + 1.8 years). Single LV strain values were significantly lower in four of the six segments compared with control LV (mid interventricular septal [IVS]: −19.3 + 6.4% vs. −23.8 + 3.5%, apical IVS: −20.8 + 5.4% vs. −27.4 + 4.7%, basal LV: −20.6 + 6.6% vs. −25.8 + 3.4%, and apical LV: −21.0 + 6.2% vs. −26.1 + 4.3%). Longitudinal displacement was lower for all three segments of the IVS for the single LV vs. control LV. Modified Yu index for strain and strain rate time to peak was longer in the single LV patients vs. controls (51.2 + 18.2 ms vs. 27.9 + 8.0 ms and 90.2 + 24.2 ms vs. 52.5 + 23.7 ms, respectively). Conclusion. Significant differences in strain analysis between single LV patients vs. control patients with normal biventricular physiology exist at a relatively young age. Future studies are needed to determine the significance of these differences.     

Left Ventricular Mechanical Synchrony and Global Systolic Function in Pediatric Patients Late after Ventricular Septal Defect Patch Closure: A Three‐dimensional Echocardiographic Study

Background. Patients with large ventricular septal defects (VSDs) undergo surgical patch closure during infancy. The long‐term effects of the presence of akinetic patch in the ventricular septum and postoperative right bundle branch block (RBBB) on the left ventricular (LV) mechanical synchrony and global systolic function have not been studied. Objective. The objective of this study was to evaluate the long‐term effects of an akinetic VSD patch and RBBB on the LV mechanical synchrony and global systolic function in pediatric patients more than 5 years after surgery. Methods. Eighteen asymptomatic VSD repair and 18 normal control patients were evaluated by an electrocardiogram and three‐dimensional echocardiography. Left ventricular end‐diastolic volumes (LVEDVs) and volumetric ejection fraction (EF) were calculated. Left ventricular intraventricular synchrony was assessed by the 16‐segment volumetric dyssynchrony index. Results. Eight of 18 (44%) patients in the VSD repair group had RBBB. The LVEDV and volumetric EF were similar in the VSD repair and control groups. The LV dyssynchrony index was not significantly different between the VSD repair and control groups (2.46 ± 1.77% vs. 1.75 ± 1.08%, P = .16). The VSD repair group was then divided into two subgroups: patients with RBBB (8/18) and those without RBBB (10/18). The two subgroups were similar in demographics, LVEDV, and volumetric EF. However, the RBBB subgroup demonstrated significant LV mechanical dyssynchrony compared with the non‐RBBB VSD subgroup (2.70 ± 1.08% vs. 1.15 ± 0.35%, P = .006). Conclusions. Pediatric patients 5–10 years after VSD patch closure have a normal LV function. The presence of the RBBB causes some mechanical dyssynchrony and tendency toward LV dilatation in this group of patients. Therefore, long‐term follow‐up of these patients is warranted.     

Impedance cardiography: a rapid and cost-effective screening tool for cardiac disease

Impedance cardiography (ICG) charts the rises and falls of thoracic impedance as the fluid content of the chest changes with each heartbeat. Breathing, arrhythmia, movements and posture interfere with the ICG. Modern pattern recognition software can now produce a composite signal-averaged ICG that considerably simplifies interpretation. The first derivative velocity waveform shows a smooth S wave that corresponds with systole, while the second derivative acceleration waveform (dZ/dt) contains several reference points that outline the A, S and O waves. Normally, the A wave follows atrial contraction and occurs in late diastole. It can, therefore, be abnormal in both atrial and ventricular arrhythmias and is abnormally increased when there is diastolic dysfunction. The S wave reflects ventricular contractility and is deformed by ventricular dyssynchrony. The O wave is associated with mitral valve opening and is abnormally enlarged in heart failure. These different patterns of ICG waveform are relatively easy to recognise and can be cost-effectively and quickly obtained to reliably distinguish between normal and abnormal cardiac function.     

超声心动图评价束支传导阻滞患者左右心室间收缩失同步

目的探讨定量组织多普勒及频谱多普勒成像观察束支传导阻滞患者左右心室间心肌收缩运动失同步的应用价值。方法完全性右束支(RBBB)及完全性左束支传导阻滞者(LBBB)各20例,正常对照者20例。测量右室游离壁、室间隔、左室侧壁基底段收缩的起始(TO)、达峰(TS)及终止时间(TSe);肺动脉瓣(PETP)与主动脉瓣的射血前间期(PETA)及其时间差(PETd)。结果RBBB组的右室壁TO、TS及PETP较正常组显著延迟(P<0.001),PETd为(43±8)ms。LBBB组的室间隔和侧壁的TO、TS、TSe及PETA均较正常组显著延迟(P<0.001),PETd为(-45±22)ms。结论定量组织多普勒能够观察到心室电-机械耦联情况,结合频谱多普勒对血流动力学的测定,可以综合评价左右心室间运动的失同步。     

Longer-term effects of cardiac resynchronization therapy on mortality in heart failure [the CArdiac REsynchronization-Heart Failure (CARE-HF) trial extension phase].

AIMS: The CArdiac REsynchronization-Heart Failure study randomized patients with left ventricular ejection fraction < or =35%, markers of cardiac dyssynchrony, and persistent moderate or severe symptoms of heart failure despite pharmacological therapy, to implantation of a cardiac resynchronization therapy (CRT) device or not. The main study observed substantial benefits on morbidity and mortality during a mean follow-up of 29.4 months [median 29.6, interquartile range (IQR) 23.6-34.6]. Prior to study closure, an extension phase lasting a further 8 months (allowing time for data analysis and presentation) was declared during which cross-over was discouraged. METHODS AND RESULTS: This was an extension of the already reported open-label randomized trial described above. The primary outcome of the extension phase was all-cause mortality from the time of randomization to completion of the extension phase. The secondary outcome was mode of death. The mean follow-up was 37.4 months (median 37.6, IQR 31.5-42.5, range 26.1-52.6 months). There were 154 deaths (38.1%) in 404 patients assigned to medical therapy and 101 deaths (24.7%) in 409 patients assigned to CRT (hazard ratio 0.60, 95% CI 0.47-0.77, P<0.0001) without evidence of heterogeneity in pre-specified subgroups. A reduction in the risk of death due to heart failure (64 vs. 38 deaths; hazard ratio 0.55, 95% CI 0.37-0.82, P=0.003) and sudden death was observed (55 vs. 32; hazard ratio 0.54, 95% CI 0.35-0.84, P=0.005). CONCLUSION: The benefits of CRT observed in the main trial persist or increase with longer follow-up. Reduction in mortality was due to fewer deaths both from worsening heart failure and from sudden death.     

Dilated cardiomyopathy in children with ventricular preexcitation: the location of the accessory pathway is predictive of this association

Background

Ventricular preexcitation may be associated with dilated cardiomyopathy, even in the absence of recurrent and incessant tachycardia.

Methods

This report describes the clinical and electrophysiologic characteristics of 10 consecutive children (6 males), with median age of 8 years (range, 1-17 years), who presented with dilated cardiomyopathy and overt ventricular preexcitation on the 12-lead electrocardiogram. Incessant tachycardia as the cause of dilated cardiomyopathy could be excluded. Coronary angiography, right ventricular endomyocardial biopsy (4/10 patients), and metabolic and microbiologic screening were nondiagnostic.

Results

The electrocardiograms suggested right-sided pathways in all patients. A right-sided accessory pathway was demonstrated in 8 patients during invasive electrophysiologic study (superoparaseptal, n = 5; septal, n = 2; fasciculoventricular, n = 1). All pathways were successfully ablated (radiofrequency ablation in 7, cryoablation in 1). Two patients had spontaneous loss of ventricular preexcitation during follow-up. Left ventricular (LV) function completely recovered after a loss of preexcitation in all patients.

Conclusions

Right-sided accessory pathways with overt ventricular preexcitation and LV dyssynchrony may cause dilated cardiomyopathy. An association between such pathways and dilated cardiomyopathy is suggested by the rapid normalization of ventricular function and reverse LV remodeling after a loss of ventricular preexcitation.