Chang Dong

ANALYSIS OF PREDICTORS OF ATRIAL FIBRILLATION AFTER PACEMAKER IMPLANTATION

Objectives Many patients post pacemaker implantation developed into atrial fibrillation (AF). The factors that can lead a greater risk of AF post implantation from different researches are controversial. As the first domestic research in long-term follow-up, we aim to investigate the risk factors of atrial fibrillation (AF) after pacemaker implantation. Methods Retrospectivel reviewed the clinical events and follow-up datas of 99 patients who accepted pacemaker implantation between January 1991 and January 2003 in our hospital. Firstly use univariate logistic regression analysis to evaluate the effects of coronary heart disease, hypertension, mitral regurgitation, LVEDD, LAD, LVEF, types of arrhythmia, pacemaker types, age and follow-up period in atrial fibrillation and then find the leading risk factors from multivariate logistic regression analysis. Results Totally 99 patients enter this research:male 48/99 (48.48%), the average age 61.10±12.42 years, SSS 49/99 (49.49%), coronary heart disease 10/99 (10.10%), hypertension 31/99 (31.31%), diabetes mellitus 8/99 (8.08%), DDD 51/99 (51.52%), VVI 48/99 (48.48%), average follow-up period is 109.48±52.08 months. Morbidity of atrial fibrillation is 29.3% (29/99). The univariate logistic regression analysis showed that coronary heart disease (p=0.034, OR=4.304,95% CI 1.114 to 16.624), LVEDD (p=0.021, OR=1.119,95% CI 1.017 to 1.232), LAD (p=0.016, OR=1.117,95% CI 1.021 to 1.221), RAD (p=0.043, OR=1.174, 95% CI 1.005 to 1.371), LEVF (p=0.003, OR=0.894, 95% CI 0.817 to 0.996) are related to the occurrence of AF after pacemaker implantation, while the multivariate logistic regression analysis showed that only the LVEF is related to the occurrence of AF after pacemaker implantation (p=0.041, OR=0.900,95% CI 0.813 to 0.996). Conclusions Compared with other middle-term studies (follow-up 1–3 years) that suggesting VVI mode tending to AF, our long-term follow-up datas reveal that the impaired LVEF is a predictor for postimplantation AF.

THE SUBSTRATE OF COMPLEX FRACTIONATED ATRIAL ELECTROGRAMS: EVIDENCE BY PATHOLOGIC ANALYSIS

Objectives Ablation of complex fractionated atrial electrograms (CFAE) is an important adjunctive therapy in atrial fibrillation (AF). The present study was to elucidate the substrate underlying CFAE. Methods Nine adult mongrel dogs were involved in the present study. AF was induced through rapid atrial pacing with vago sympathetic nerve stimulation. CFAE was recorded during AF. Ablation was performed at CFAE sites. Based on the location of the ablation scar, the atrial specimens were divided into CFAE and non-CFAE sites. Serial sections of the atrium were stained respectively with haematoxylin_eosin (HE) and the general neural marker protein gene product 9.5 (PGP9.5). We compared the characteristics of the myocardium and the ganglionated plexus (GPs) distribution between the CFAE and non-CFAE sites. Results The myocardium of non-CFAE sites was well-organised with little intercellular substance. However, the myocardium in the CFAE site was disorganised with more interstitial tissue (61.7±24.3% vs 34.1±9.2%, p<0.01). GPs in the CFAE site were more abundant than in non-CFAE sites ((34.45±37.46) bundles/cm2 vs (6.73±8.22) bundles/cm2, p<0.01). Conclusions The heterogeneity of the myocardium and GPs distribution may account for the substrate of CFAE and serve as a potential target of ablation.

EFFECT OF VAGAL NERVE ON THE MONOPHASIC ACTION POTENTIAL OF VENTRICULAR OUTFLOW TRACT

Objectives Vagal nerve may be related with idiopathetic ventricular tachycardia (IVT). The present study was aimed to investigate the effect of vagal nerve on the monophasic action potential (MAP) of ventricular outflow tract. Methods Eight adult mongrel dogs were involved. Bilateral vagosympathetic tunks were decentralised for stimulation. Metoprolol was given to block sympathetic effects. MAP was recorded at the LVOT, RVOT, RVA with or without vagal stimulation (VS) respectively. Results 90% of MAP duration (MAPD90) under VS was significantly shorter than baseline (p>0.05). With or without VS, the MAPD90 of RVA were significantly shorter than RVOT and LVOT (p<0.05), while there was no difference of MAPD90 between RVOT and LVOT. With VS, the abbreviation of MAPD90 at LVOT and RVOT was greater significantly than RVA (MAPD90: 12.1±3.9 at RVOT, 14.8±5.5 at LVOT vs 8.3±4.1 at RVA, p<0.05), while there was no difference of MAPD between LVOT and RVOT (p>0.05). Conclusions VS could reduce MAPD significantly. With VS, the abbreviation of MAPD90 at LVOT and RVOT was greater significantly than RVA. It suggested that outflow tract may be sensible to vagal modulation, which might be related to the occurrence of IVT. Conclusions VS could reduce MAPD significantly. With VS, the abbreviation of MAPD90 at LVOT and RVOT was greater significantly than RVA. It suggested that outflow tract may be sensible to vagal modulation, which might be related to the occurrence of IVT.