ABSTRACT
Objective: To study the incidence of ventricular arrhythmia (VT) in heart failure (HF) patients after cardiac resynchronization therapy (CRT-D) and identify the influencing factors for VT occurrence, to explore the impact of CRT-D shocks on mortality and the management of appropriate shocks. Methods: A total of 42 patients with successfully implanted CRT-D in our hospital from 2009-01 to 2015-04 were studied. There were 2 groups of patients: Ischemic cardiomyopathy group,n=12 including 8 patients for primary prevention and 4 for secondary prevention; Non-ischemic cardiomyopathy group,n=30 including 19 patients for primary prevention and 11 for secondary prevention. The patients with appropriate shocks received four step-wise therapy as drug, equipment parameter adjustments, revascularization and radiofrequency ablation (RA). Results: The patients in Ischemic cardiomyopathy group were followed-up for (38.1±24.0) months, 7 patients suffered from post-operative VT, 5 patients had CRT-D appropriate shocks. The patients in Non-ischemic cardiomyopathy group were followed-up for (27.5±17.8) months, 11 patients suffered from post-operative VT, 10 patients had CRT-D appropriate shocks. The occurrence rates of post-operative VT and CRT-D appropriate shocks were similar between 2 groups,P>0.05; the success rate for ATP treating VT was higher in Ischemic cardiomyopathy group (69% vs 55%),P<0.05. Cox regression analysis indicated that CRT-D as secondary prevention was the independent influencing factor for VT occurrence,P=0.001. During follow-up period, 9 patients with shocks died; the mortality in patients with shocks was higher than those without shocks (43% vs 0%),P<0.05. With four step-wise therapy, 80% patients in Ischemic cardiomyopathy group had no more shocks; with three step-wise therapy as drug, equipment parameter adjustments and RA, 90% patients in Non-ischemic cardiomyopathy group had no more shocks, 10% patients had reduced shocks. Conclusion: CRT-D as secondary prevention was the independent impact factor for post-operative VT occurrence, no matter appropriate or inappropriate shocks would elevate the risk of death in HF patients. Step-wise therapy was important to reduce appropriate shocks.
ABSTRACT
Background Atrial electrical remodeling(AER)plays an important role in the pathogenesis and maintenance of atrialfibrillation.However,little is known about modulation of vagal activilty to AER.This study aimed to investigate the relationshipbetween vagal moduation and AER. Methods Twenty four adult mongrel dogs under general anesthesia were randomized into 3groups.Sympathetic activity was blocked by administration of metoprolol in 3 groups.The changes in vagal modulation to atria afterAER were observed in 10 dogs without vagal interruption in group A.The effects of vagal intervention on AER were investigated in 8dogs with administration of atropine in group B.The impact of aggressively vagal activity on AER was studied in 6 dogs with bilateralcervical vag sympathetic trunLks stimulation during AER in group C.Bilateral cervicall vagosympathetic trunks were decentralized.Multipolar catheters wereplaced into high right atria(RA),coronary sinus(CS)and rightventricle(RV).AER was induced by 600 bpmpacing through RA catheter for 30 minutes.Attial effective refractory period(ERP)and vulnerability window (VW)of atrial fibrillationwere measured with and without vagal stimulation before and after AER.Results In group A,ERP decreased significantly at baselineand during vagal stimulation after AER compared with that beforeAER(all P＜0.05).In group B,ERP remaind unchanged at baselineand vagal stimulation after AER compared with tbat before AER (all P＞0.05).In group C,ERP shortened significantly at baseline andvagal stimulation after AER compared with that before AER(all P＜0.05).ERP shortening after AER in Groups A and C increasedsignificantly than that in group B (all P＜0.05).Atrial fibrillation could not be induced at baseline(VW close to 0) before and after AERin three groups.VW became widen significantly during vagal stimulation after AER compared with that before AER in Groups A and C(all P＜0.05),while VW remained unchanged in group B (VW close to 0).Conclusions Short-term AER results in the decrease inERP.AER is accompanied by the increases in atrial vagal modulation.The increased vagal activity and vagal stimulation promote AER,thereby increase the susceptibility to atrial fibrillation.The interrupted vagal activity attenuates AER.thereby suppresses the atriaIfibrillation mediated by vagal stimutlation.