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Background: The objective of this study was to detect differences in the distribution of the left and right ventricle (LV & RV) activation rate (AR) during short-duration ventricular fibrillation (SDVF, <1 min) and long-duration ventricular fibrillation VF (LDVF, >1 min) in normal and heart failure (HF) canine hearts.Methods: Ventricular fibrillation (VF) was electrically induced in six healthy dogs (control group) and six dogs with right ventricular pacing-induced congestive HF (HF group). Two 64-electrode basket catheters deployed in the LV and RV were used for global endocardium electrical mapping. The AR of VF was estimated by fast Fourier transform analysis from each electrode.Results: In the control group, the LV was activated faster than the RV in the first 20 s, after which there was no detectable difference in the AR between them. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the posterior LV was activated fastest, while the anterior was slowest. In the HF group, a detectable AR gradient existed between the two ventricles within 3 min of VF, with the LV activating more quickly than the RV. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the septum of the LV was activated fastest, while the anterior was activated slowest.Conclusions: A global bi-ventricular endocardial AR gradient existed within the first 20 s of VF but disappeared in the LDVF in healthy hearts. However, the AR gradient was always observed in both SDVF and LDVF in HF hearts. The findings of this study suggest that LDVF in HF hearts can be maintained differently from normal hearts, which accordingly should lead to the development of different management strategies for LDVF resuscitation. [ABSTRACT FROM AUTHOR]

Objective: To observe the clinical effects of cardiac resynchronization therapy (CRT) in patients with chronic heart failure, and compare the clinical characteristics and outcome between responders and non-responders to define factors related to the efficacy of CRT., Methods: We retrospectively analyzed the data of patients underwent CRT-P/D implantation from January 2006 to December 2012 in our Hospital. All patients received long-term follow-up including NYHA classification, left ventricular ejection fraction (LVEF) and left ventricular internal dimension at end diastole (LVIDd)., Results: A total of 204 patients were included (130 males, mean age (64.8 ± 11.9) years). The total response rate of CRT was 61.3%. Women, QRS duration ≥ 150 ms, and left bundle branch block (LBBB) were related with better response after CRT (all P < 0.05). Multivariate regression analysis showed that QRS duration was an independent determinant for CRT response. All-cause mortality rate was significantly lower in responder group than in non-responder group (P < 0.001)., Conclusions: In patients with chronic heart failure, women, QRS duration ≥ 150 ms, and LBBB are related with better CRT response rate post CRT. QRS duration ≥ 150 ms is an independent predictor of CRT response, and positive response is associated with lower all-cause mortality in this patient cohort.