Relationship between electrocardiographic characteristics of left bundle branch block and echocardiographic findings

Background: Complete left bundle branch block (CLBBB) is an electrocardiographic (ECG) dromotropic disorder seen in patients with various structural heart diseases and sometimes is associated with poor prognosis. Its presence confounds the application of standard ECG criteria for the diagnosis of left ventricular hypertrophy (LVH), myocardial infarction (MI) in the chronic phase, and pathologies that produce changes on ST-T segment. The aim of this investigation was to establish the relationship between CLBBB and cardiac structural abnormalities assessed by echocardiography. Methods: This observational, cross-sectional study included ECG with CLBBB from 101 patients who also had transthoracic echocardiogram (TTE) performed within 6 months. Results: The prevalence of structural heart disease on TTE was 90%. No ECG criterion was useful to diagnose LVH since no relationship was observed between 9 different ECG signs and increased left ventricular mass index. QRS duration (p = 0.16) and left axis deviation (p = 0.09) were unrelated to reduced left ventricular ejection fraction (LVEF). Eight ECG signs proposed for the diagnosis of the chronic phase of MI demonstrated similar effectiveness, with high specificity and reduced sensitivity. Conclusions: CLBBB is associated with elevated prevalence of cardiac structural disease and hinders the application of common ECG criteria for the diagnosis of LVH, reduced LVEF, or chronic phase of MI. No ECG finding distinguished patients with structural heart disease from those with normal hearts. Electrocardiographic criteria for the diagnosis of MI in the chronic phase are useful when present, but when absent cannot rule it out.

Improving exercise tolerance with catheter ablation

Abstract not availableAdrian D. Elliott, Ricardo S. Mishima, Dennis H. Lau, Prashanthan Sander

Exercise echocardiography to assess left atrial function in patients with symptomatic AF

Background: Left atrial (LA) function contributes to the augmentation of cardiac output during exercise. However, LA response to exercise in patients with atrial fibrillation (AF) is unknown. We explored the LA mechanical response to exercise and the association between LA dysfunction and exercise intolerance. Methods: We recruited consecutive patients with symptomatic AF and preserved left ventricular ejection fraction (LVEF). Participants underwent exercise echocardiography and cardiopulmonary exercise testing (CPET). Two-dimensional and speckle-tracking echocardiography were performed to assess LA function at rest and during exercise. Participants were grouped according to presenting rhythm (AF vs sinus rhythm). The relationship between LA function and cardiorespiratory fitness in patients maintaining SR was assessed using linear regression. Results: Of 177 consecutive symptomatic AF patients awaiting AF ablation, 105 met inclusion criteria; 31 (29.5 %) presented in AF whilst 74 (70.5 %) presented in SR. Patients in SR augmented LA function from rest to exercise, increasing LA emptying fraction (LAEF) and LA reservoir strain. In contrast, patients in AF demonstrated reduced LAEF and reservoir strain at rest, with failure to augment either parameter during exercise. This was associated with reduced VO2Peak compared to those in SR (18.4 ± 5.6 vs 22.5 ± 7.7 ml/kg/min, p = 0.003). In patients maintaining SR, LAEF and reservoir strain at rest and during exercise were associated with VO2Peak, independent of LV function. Conclusion: The maintenance of SR in patients with AF is associated with greater LA reservoir function at rest and greater augmentation with exercise compared to patients in AF. In patients in SR, reduced LA function is associated with reduced exercise tolerance, independent of LV function

Normalizing treatment influence on the forged steel SAE 8620 fracture properties

In a PWR nuclear power plant, the reactor pressure vessel (RPV) contains the fuel assemblies and reactor vessels internals and keeps the coolant at high temperature and high pressure during normal operation. The RPV integrity must be assured all along its useful life to protect the general public against a significant radiation liberation damage. One of the critical issues relative to the VPR structural integrity refers to the pressurized thermal shock (PTS) accident evaluation. To better understand the effects of this kind of event, a PTS experiment has been planned using an RPV prototype. The RPV material fracture behavior characterization in the ductile-brittle transition region represents one of the most important aspects of the structural assessment process of RPV's under PTS. This work presents the results of fracture toughness tests carried out to characterize the RPV prototype material behavior. The test data includes Charpy energy curves, T0 reference temperatures for definition of master curves, and fracture surfaces observed in electronic microscope. The results are given for the vessel steel in the "as received" and normalized conditions. This way, the influence of the normalizing treatment on the fracture properties of the steel could be evaluated