Objective features of the surface electrocardiogram during ventricular tachyarrhythmias

The aim of this study was to quantify the electrocardiographicsignal characteristics of three types of ventricular arrhythmia;monomorphic ventricular tachycardia, polymorphic ventriculartachycardia and ventricular fibrillation. Patients in a coronarycare unit were monitored using a single bipolar ECG lead. Thirtyepisodes of ventricular tachyarrhythmia (ten from each group)were recorded automatically by computer. Frequency analysisof ten consecutive 1 s epochs from each recording gave 100 spectrafor each tachyarrhythmia group. Each spectrum was characterisedby the frequency, width and proportional size of the dominantpeak. Despite a qualitative similarity in spectral appearance,there were significant differrences in all characteristics betweenthe tachyarrhythmia groups (P<0·025). Ventricularfibrillation had a higher mean dominant frequency (4·8Hz) than polymorphic ventricular tachycardia (3·7 Hz)and monomorphic ventricular tachycardia (3·8 Hz). Thedominant frequency of ventricular fibrillation was also morevariable than that of monomorphic ventricular tachycardia (P<0·01).Mean peak size was largest for monomorphic ventricular tachycardia(0·78) and smallest for ventricular fibrillation (0·64).The single spectral peaks seen throughout this study indicatethat all three tachyarrhythmias have an underlying periodicmechanism. The difference in spectral characteristics show thatvarying degrees of myocardial electrical organisation can bequantified from surface ECG features.     

Repolarization heterogeneity in patients with cardiac resynchronization therapy and its relation to ventricular tachyarrhythmias

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Sotalol in patients with life-threatening ventricular tachyarrhythmias

Summary To assess the antiarrhythmic efficacy of oral d,l-sotalol, 68 patients with sustained monomorphic ventricular tachycardia (SMVT) (n=62) or ventricular fibrillation (VF) (n=6) were studied by programmed ventricular stimulation (PVS). Fifty-one patients had coronary artery disease with a previous myocardial infarction and there were 17 patients without coronary disease: 11 patients had right and/or left ventricular dysplasia, one patient an aortic-valve replacement, and five patients had no visible heart disease. Prior to sotalol patients were treated with a mean of 3.6±1.3 antiarrhythmic class I drugs. None of these drugs prevented SMVT or VF. During control PVS (PVS 1), VF was induced in 8 patients (12%), SMVT in 47 patients (69%), and nonsustained ventricular tachycardia (NSVT) in 13 patients (19%). After loading with oral d,l-sotalol (320 mg/day), PVS (PVS 2) was repeated 4.2±3.3 weeks after PVS 1. In one of the patients (1%) VF was inducible, in 15 patients (22%) SMVT was induced, and in 18 patients (26%) NSVT was induced. In 34 patients (50%) either no or a short ventricular response was inducible. Our data show that oral d,l-sotalol is an effective antiarrhythmic agent in patients with SMVT or VF.     

121例住院患者心室颤动的临床分析

目的探讨患者住院期间心室颤动（VF）的基础原因、复苏影响因素及随访结果,以对医院内、外猝死的抢救有所指导。方法2006年1月1日至12月31日,2所三级医院和12所二级医院住院期间共121例患者发生VF,对其临床资料进行回顾性分析。结果住院期间VF的复苏成功率51．2％;冠心病与非冠心病VF的复苏成功率分别为55．8％和23．5％（P=0．014）;监护区与无监护区VF的复苏成功率分别为80．6％和38．8％（P=0．001）;血钾正常与低钾血症VF复苏成功率58．6％和60．0％（P=0．932）;三级医院与二级医院VF复苏成功率为65．2％和42．7％（P=0．016）;62例复苏成功的VF患者中,住院期间死亡4例,平均随访时间（12±3）个月,随访期间死亡5例。结论住院期间VF的病死率较高;冠心病并发VF的复苏成功率高于非冠心病;直流电除颤是重要的抢救措施;低钾血症不影响VF的复苏成功率;三级医院的复苏成功率高于二级医院。     

Exploring QT interval changes as a precursor to the onset of ventricular fibrillation/tachycardia

In the present study, we have retrospectively analyzed the corrected QT (QTc) interval before spontaneous episodes of sudden cardiac arrest in patients with a wearable cardioverter defibrillator. Corrected QT interval was measured for all normal beats from 32 recordings of baseline rhythm and compared to normal rhythm before a paired spontaneous cardiac arrhythmia. Before arrhythmia, the QTc (505 ± 73 ms) was not significantly longer than the baseline rhythm (497 ± 73 ms) (P = .23). Considering ventricular tachycardia (VT) events only (12 patients), event QTc (526 ± 75 ms) was not significantly longer than baseline QTc (520 ± 74 ms) (P = .41). Considering fast VT/ventricular fibrillation (VF) events only (20 patients), event QTc (494 ± 70 ms) was not significantly longer than baseline QTc (483 ± 71 ms) (P = .26). The influence of QTc as a measure to indicate an impending VT event in a variety of VT/VF patients remains unclear.     

植入型心律转复除颤器治疗恶性室性心律失常的疗效评价

目的评价单中心40例植入型心律转复除颤器(ICD)治疗恶性室性心律失常的疗效及安全性。方法40例恶性室性心律失常包括室性心动过速(室速)或心室颤动(室颤)患者接受ICD治疗,男性35例,女性5例,平均年龄(49±15)岁,成功随访35例,应用体外程控仪获得ICD储存资料并结合临床随访资料进行分析。结果40例患者均成功植入ICD;35例患者平均随访25个月,其中26例患者共记录室速和室颤事件763阵,ICD成功除颤224阵(成功率99．1％),抗心动过速起搏1次成功终止室速375阵(成功率71．8％),低能量同步转复22阵(成功率100％);2例患者因窦性心动过速和心房颤动伴快速心室反应发生误放电4次。术后大多数患者联合应用抗心律失常药物。至随访期末,死亡4例,3例死于顽固性心力衰竭,1例死于肺栓塞。结论ICD联合应用抗心律失常药物能有效治疗恶性室性心律失常,预防心脏性猝死。     

Trends in treated ventricular fibrillation out-of-hospital cardiac arrest: A 17-year population-based study

OBJECTIVES: The aims of this study were to describe the trends of ventricular fibrillation (VF) out-of-hospital cardiac arrest in Rochester, Minnesota, since 1985 and to determine coexistent trends in implantable cardioverter defibrillator (ICD) placement and termination of potentially lethal ventricular arrhythmias that might explain, at least in part, a declining incidence trend. BACKGROUND: The incidence of VF out-of-hospital cardiac arrest treated by emergency medical services (EMS) personnel has declined over the past decade. Because VF out-of-hospital cardiac arrest occurs primarily in the setting of severe coronary artery disease, primary and secondary prevention strategies may account in part for the decline. In particular, ICD use in large primary and secondary prevention clinical trials in patients at high risk of sudden death has demonstrated that these devices improve survival. METHODS: All residents of the City of Rochester, Minnesota, who presented with a VF out-of-hospital cardiac arrest from 1985 to 2002, identified and treated by EMS, were included in the study. In addition, residents of the City of Rochester who received their first ICD implant from 1989 to 2002 were identified. From the ICD records, general demographics, etiology of heart disease, comorbid medical disease, and indication for ICD placement were abstracted. Follow-up data obtained from this population included ICD shocks, the underlying rhythm disturbance, and death. RESULTS: The overall incidence of EMS-treated VF out-of-hospital cardiac arrest in Rochester during the study period was 17.1 per 100,000 [95% confidence interval (CI) 15.1-19.4]. The incidence has decreased significantly (P < 0.001) over the study period: 1985-1989: 26.3/100,000 (95% CI 21.0-32.6), 1990-1994: 18.2/100,000 (95% CI 14.1-23.1), 1995-1999: 13.8/100,000 (95% CI 10.4-17.9), 2000-2002: 7.7/100,000 (95% CI 4.7-11.9). One hundred ten patients received an ICD. The placement of ICDs also has increased dramatically over the past 10 years: 1990-1994: 5.0/100,000 to 2000-2002: 20.7/100,000 (P < 0.001). ICDs terminated VF or fast ventricular tachycardia (<270 ms) in 22 patients. Termination of these potentially fatal arrhythmias has shown a trend toward an increase over the study period: 1990-1994: 1.1/100,000 to 2000-2002: 3.5/100,000 (P = 0.06). CONCLUSIONS: The incidence of VF out-of-hospital cardiac arrest is declining. In contrast, the rates of ICD placement and ICD termination of ventricular tachycardia or VF are markedly increasing. Sudden death preventive strategies are multifactorial. These observations suggest that ICD termination of potentially lethal ventricular arrhythmias may contribute to the lower incidence of VF out-of-hospital cardiac arrest.     

HCN212-channel biological pacemakers manifesting ventricular tachyarrhythmias are responsive to treatment with If blockade

BACKGROUND: A potential concern about biological pacemakers is their possible malfunction, which might create ventricular tachycardias (VTs). OBJECTIVE: The purpose of this study was to test our hypothesis that should VTs complicate implantation of HCN-channel-based biological pacemakers, they would be suppressed by inhibitors of the pacemaker current, I(f). METHODS: We created a chimeric channel (HCN212) containing the N- and C-termini of mouse HCN2 and the transmembrane region of mouse HCN1 and implanted it in HEK293 cells. Forty-eight hours later, in whole-cell patch clamp recordings, mean steady state block induced by 3 microM ivabradine (IVB) showed HCN1 = HCN212 > HCN2 currents. The HCN212 adenoviral construct was then implanted into the canine left bundle branch in 11 dogs. Complete AV block was created via radiofrequency ablation, and a ventricular demand electronic pacemaker was implanted (VVI 45 bpm). Electrocardiogram, 24-hour Holter monitoring, and pacemaker log record check were performed for 11 days. RESULTS: All dogs developed rapid VT (>120 bpm, maximum rate = 285 +/- 37 bpm) at 0.9 +/- 0.3 days after implantation that persisted through 5 +/- 1 days. IVB, 1 mg/kg over 5 minutes, was administered during rapid VT, and three dogs received a second dose 24 hours later. While VT terminated with IBV in all instances within 3.4 +/- 0.6 minutes, no effect of IVB on sinus rate was noted. CONCLUSION: We conclude that (1) I(f)-associated tachyarrhythmias-if they occur with HCN-based biological pacemakers-can be controlled with I(f)-inhibiting drugs such as IVB; (2) in vitro, IVB appears to have a greater steady state inhibiting effect on HCN1 and HCN212 isoforms than on HCN4; and (3) VT originating from the HCN212 injection site is suppressed more readily than sinus rhythm. This suggests a selectivity of IVB at the concentration attained for ectopic over HCN4-based pacemaker function. This might confer a therapeutic benefit.     

Out-of-hospital cardiac arrest caused by transient left ventricular apical ballooning syndrome

We describe a case of out-of-hospital cardiac arrest due to ventricular fibrillation in a patient with transient left ventricular apical ballooning syndrome. Our report confirms that left ventricular apical ballooning may have the same complications of myocardial infarction, adding the early ventricular fibrillation to the previous findings of left ventricular wall rupture, ventricular arrhythmias during hospitalization and complete atrio-ventricular block. Moreover, left ventricular apical ballooning may have different and unusual clinical onsets, including sudden cardiac death due to ventricular tachyarrhythmias in the absence of associated symptoms. Therefore, in our opinion left ventricular apical ballooning may be considered as a possible cause of sudden death in otherwise healthy women.     

急性心肌梗死患者急诊介入治疗中发生室性心动过速或心室颤动的预测因子和预后

目的评估急性ST段抬高性心肌梗死（STEMI）患者在导管室行急诊冠状动脉介入治疗（PCI）中室性心动过速或心室颤动（VT／VF）的发生率、预测因子和预后。方法调查了1136例症状发生后12h内行急诊PCI的急性STEMI患者，评估其VT／VF的发生率、预测因子和对患者住院期间及1年预后的影响。研究根据PCI术中发生VT／VF与否分为VT／VF组和无VT／VF组。结果1136例急性STEMI患者中在导管室PCI术中发生VT／VF62例（5．5％）。多元回归分析提示下列为发生VT／VF的预测因子：吸烟[相对危险度（OR）1．89，95％可信区间（CI）1．19-2．96]，缺乏应用β受体阻滞剂（OR2．54，95％ CI 1．45-4．27），从胸痛症状发生至入急诊室的时间〈180min（OR2．83，95％ CI 1．62-5．37），术前造影冠状动脉血流TIMI分级0级（OR2．44，95％ CI 1．45-3．89）和右冠状动脉作为梗死相关动脉（OR2．11，95％ CI 1．35-3．02）。随着危险因子的增加VT／VF的发生率也相应增加，从没有危险因子的0发生率到具有全部5个危险因子的14．0％发生率。VT／VF组与无VT／VF组患者住院期间和1年的预后相似（P〉0．05）。结论急性STEMI患者在导管室急诊PCI中VT／VF发生率低、治愈率高，对PCI成功率及住院期间和1年的临床结果无明显影响。本研究有助于发现存在发生VT／VF危险的患者，并强烈提示术前应用β受体阻滞剂可减少这些心律失常的发生。