Results of Delivered Therapy for VT or VF in Patients with Third-Generation Implantable Cardioverter Defibrillators

Third-generation implantable cardioverter defibrillators (ICDs) offer tiered therapy and can provide significant advantage in the management of patients with life-threatening arrhythmias. Three different types of ICDs were implanted in 21 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia presentation was VT(76%), VF(10%), or both (14%). The mean left ventricular ejection fraction for the group was 32.4 ± 7%. No surgical mortality occurred. Prior to discharge individual EPS determined the final programmed settings of the ICDs. During a mean follow-up of 13 ± 1.4 months (range 2–20) the overall patient survival was 85.7%. No sudden arrhythmic or cardiac death occurred. Twenty of 21 patients (95%) received therapy by their device. In 14 patients (67%) antitachycardia pacing (A TP) was programmed "on," 13 of which was self-adaptative autodecremental mode. There were 247 VT episodes, 231 of which were subjected to ATP with 97% success and 3% acceleration or failure. Low energy shocks reverted all other VT episodes. VF episodes were successfully reverted by a single shock (93%), two shocks (6%), or three shocks (1 %). We conclude that ATP therapy of VT is successful in the large majority of episodes with rare failures, and that VF episodes are generally terminated by a single ICD shock.     

Ventricular Arrhythmia Inducibility Predicts Subsequent ICD Activation in Nonischemic Cardiomyopathy Patients: A DEFINITE Substudy

Objectives: We evaluated whether electrophysiologic (EP) inducibility predicts the subsequent occurrence of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.
Background: Inducibility of ventricular arrhythmias has been widely used as a risk marker to select implantable cardioverter defibrillator (ICD) candidates, but is believed not to be predictive in nonischemic cardiomyopathy patients.
Methods: In DEFINITE, patients randomized to the ICD arm, but not the conventional arm, underwent noninvasive EP testing via the ICD shortly after ICD implantation using up to three extrastimuli at three cycle lengths plus burst pacing. Inducibility was defined as monomorphic or polymorphic VT or VF lasting 15 seconds. Patients were followed for a median of 29 ± 14 months (interquartile range = 2–41). An independent committee, blinded to inducibility status, characterized the rhythm triggering ICD shocks.
Results: Inducibility, found in 29 of 204 patients (VT in 13, VF in 16), was associated with diabetes (41.4% vs 20.6%, P = 0.014) and a slightly higher ejection fraction (23.2 ± 5.9 vs 20.5 ± 5.7, P = 0.021). In follow-up, 34.5% of the inducible group (10 of 29) experienced ICD therapy for VT or VF or arrhythmic death versus 12.0% (21 of 175) noninducible patients (hazard ratio = 2.60, P = 0.014).
Conclusions: In DEFINITE patients, inducibility of either VT or VF was associated with an increased likelihood of subsequent ICD therapy for VT or VF, and should be one factor considered in risk stratifying nonischemic cardiomyopathy patients.     

临时心脏起搏治疗长间歇依赖室早诱发恶性快速性室性心律失常（附14例报告）

目的探讨临时心脏起搏救治长间歇依赖早搏诱发的恶性快速性室性心律失常的疗效及安全性。方法长间歇依赖室性早搏诱发的恶性快速性室性心律失常所导致的心源性晕厥或猝死患者共14例，包括尖端扭转型室性心动过速（TdP）8例，室颤（w）5例（2例由TdP转化而来），持续性单形性室性心动过速（VT）1例，呈反复发作的特点，予临时心脏起搏治疗。结果临时心脏起搏救治长间歇依赖室早诱发的恶性快速性室性心律失常疗效明显，8例TdP和1例VT的治愈率100％，5例VF的治愈率40％，死亡3例。结论临时心脏起搏救治长间歇依赖室早诱发的恶性快速性室性心律失常安全有效。     

Transcutaneous T Wave Shock: A Universal Method for Ventricular Fibrillation Induction

Our objective was to develop a universal noninvasive method for VF induction. ICD implantation requires VF induction. Conventional rapid ventricular stimulation may fail to induce VF. Some ICDs can deliver low energy shocks on the T wave to induce VF. We hypothesized that an external dual chamber pacemaker and an external defibrillator could be configured to allow reliable VF induction with any ICD system. A surface ECC signal was delivered to the atrial channel of an external dual chamber DDD pacemaker. The 'AV' delay was adjusted so that the ventricular output of the pacemaker was delivered to an external defibrillator synchronized to deliver 5–50 J. Twenty-six patients at ICD implant or follow-up had VF induced in native rhythm (sinus rhythm or atrial fibrillation), or during a ventricular pacing train (3–8 beats at cycle length 500–880 ms). VF was successfully induced in 14 of 25 (56%) patients in native rhythm; and in 16 of 17 (94%) patients during pacing (P = 0.013). VF induction success rate was 36% in native rhythm (31/86 attempts) and 88% during pacing (69/78 attempts) (P < 0.001). The 'R' to shock interval was 269 ± 31 ms in native rhythm and 257 ± 48 ms during pacing. Energy delivered from the external defibrillator was 19 ± 3 J in native rhythm and 21 ± 6 J during pacing. We concluded that VF induction by synchronizing a small external shock to the T wave is a fast, effective way to reliably ensure arrhythmia induction with any ICD at implant or follow-up. This method is more successful during pacing than in sinus rhythm.     

Sustained polymorphic arrhythmias induced by programmed ventricular stimulation have prognostic value in patients receiving defibrillators

BACKGROUND: Patients with ischemic cardiomyopathy (ICM) who have monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation (PVS) are at increased risk of sudden cardiac death (SCD). Among a primary prevention population, the prognostic significance of induced polymorphic ventricular arrhythmias is unknown. METHODS: A total of 105 consecutive patients who received an implantable cardioverter-defibrillator (ICD) for primary prevention of SCD in the setting of ICM and non-sustained VT were retrospectively evaluated. Seventy-five patients (group I) had induction of monomorphic VT and 30 patients (group II) had a sustained ventricular arrhythmia other than monomorphic VT (ventricular flutter, ventricular fibrillation, and polymorphic VT) induced during PVS. RESULTS: Baseline characteristics were similar between group I and group II except for ejection fraction (25% vs. 31%, P = 0.0001) and QRS duration (123 milliseconds vs. 109 milliseconds, P = 0.04). Sixteen of 75 (21.3%) patients in group I and 6 of 30 (20%) patients in group II received appropriate ICD therapy (P = 0.88). Survival free from ICD therapy was similar between groups (P = 0.54). There was a trend toward increased all-cause mortality among patients in group I by Kaplan-Meier analysis (P = 0.08). However, when adjusted for age, EF, and QRS duration mortality was similar (P = 0.45). CONCLUSIONS: There is no difference in rates of appropriate ICD discharge or mortality between patients dichotomized by type of rhythm induced during PVS. These results suggest that patients in this population who have inducible VF or sustained polymorphic VT have similar rates of subsequent clinical ventricular tachyarrhythmias as those with inducible monomorphic VT.     

Late Gadolinium Enhancement in Patients with Nonischemic Dilated Cardiomyopathy

One‐third of all patients with heart failure have nonischemic dilated cardiomyopathy (NIDM). Five‐year mortality from NIDM is as high as 20% with sudden cardiac death (SCD) as the cause in 30% of the deaths. Currently, the left ventricular ejection fraction (LVEF) is used as the main criteria to risk stratify patients requiring an implantable cardioverter defibrillator (ICD) to prevent SCD. However, LVEF does not necessarily reflect myocardial propensity for electrical instability leading to ventricular tachycardia (VT) or ventricular fibrillation (VF). Due to the differential risk in various subgroups of patients for arrhythmic death, it is important to identify appropriate patients for ICD implantation so that we can optimize healthcare resources and avoid the complications of ICDs in individuals who are unlikely to benefit. We performed a systematic search and review of clinical trials of NIDM and the use of ICDs and cardiac magnetic resonance imaging with late gadolinium enhancement (LGE) for risk stratification. LGE identifies patients with NIDM who are at high risk for SCD and enables optimized patient selection for ICD placement, while the absence of LGE may reduce the need for ICD implantation in patients with NIDM who are at low risk for future VF/VT or SCD.     

The Value of Electrophysiology Study and Prophylactic Implantation of Cardioverter Defibrillator in Patients with Hypertrophic Cardiomyopathy

Fifty-three consecutive patients with hypertrophic cardiomyopathy (HCM) and no history of sudden death underwent electrophysiology (EP) study. Sustained polymorphic ventricular tachycardia (VT) or ventricular fibrillation (VF) was induced in 19 patients (35%). Patients with prior syncope or near syncope had a higher incidence of VT/VF inducibility. An implantable cardioverter defibrillator (ICD) was placed in 14 of the 19 patients. Of the remaining 5 patients with inducible VT/VF, three refused ICD implantation, while two underwent septal myectomy and VT/VF was no longer inducible afier the operation. None of the patients received antiarrhythmic drugs. During a mean follow-up period of 47 ± 31 (2–117) months, no events occurred in the 34 patients with negative EP study. Three events occurred among the 19 patients with inducible VT/VF. One patient died suddenly, one developed wide complex tachycardia which required resuscitation, and one patient received an appropriate ICD shock. In conclusion, sustained polymorphic VT/VF was inducible in about one-third of patients with HCM. Noninducibility of VT/VF appeared to predict a favorable prognosis. Although the overall event rate was low in patients with inducible VT/VF, prophylactic ICD implantation in patients with multiple risk factors may be appropriate.     

Preliminary Clinical Experience with the First Dual Chamber Pacemaker Defibrillator

The lack of specificity of VT detection is a significant shortcoming of current ICDs. In a French multicenter study, 18 patients underwent implantation of the Defender 9001 (ELA Medical), an ICD utilizing dual chamber pacing and arrhythmia detection. Over a mean follow-up period of 7.1 ± 4.5 months, 176 tachycardia episodes recorded in the device memory were analyzed, and physician diagnosis was compared with that by the device. All 122 VT/VF episodes were correctly diagnosed, as were 51 of 53 supraventricular tachyarrhythmias. Two episodes of AF with rapid regular ventricular rates were treated as VT, and a third episode, treated as VT, could not be diagnosed with certainty. A dual chamber pacemaker defibrillator offers improved diagnostic specificity without loss of sensitivity, in addition to the hemodynamic benefit of dual chamber pacing. (PACE 1997;20     

Long-Term Efficacy of an Antitachycardia Pacemaker and Implantable Defibrillator Combination

Antitachycardia pacemakers and implantable cardioverter defibrillators (ICD) were implanted in 14 patients to control recurrent hemodynamically stable ventricular tachycardia (VT), All patients underwent extensive preimplant testing in the elecrrophysiology laboratory documenting that in each patient at least 50 episodes of VT could be reliably terminated by an external model of the antitachycardia pacemaker. The burst scanning mode of anfitachycardia pacing was used in all patients. ICDs were implanted solely as a back up should acceleration of VT occur, and all had high nonprogrammable rate cutoffs (mean 191 ± 12 beats/min). During a mean follow-up of 25 ± 6 months, 6,029 episodes of VT were treated in the 14 patients. Only 103 ICD discharges were required (approximately one discharge per 60 episodes of VT). Ten of the 14 patients received discharges from their ICDs. No deaths have occurred. All devices remain active and in the automatic mode. Thus, an antitachycardia pacemaker and ICD combination can safely and effectively terminate VT in highly selected patients who are subjected to extensive preimplant testing. In such patients, the vast majority of episodes of VT can be terminated with antitachycardia pacing, and only rarely is a discharge required from the ICD.     

Does resuscitation training affect outcome from cardiac arrest?

It is established that basic life support (BLS) is performed inadequately by both nursing and medical staff and that the ability to retain these skills, once trained, is low. In addition, the initial success rate from cardiopulmonary arrest is poor. By implementing the advanced life support (ALS) course and providing frequent updates on resuscitation skills and management, it is expected that cardiac arrest outcome results should improve. This data is from a 4 year audit of in-hospital cardiac arrest within an adult patient group between January 1993 and December 1996. The average return response of all audit forms was 86.5%. The total sample consisted of 367 separate arrests where the initial rhythm was documented as either ventricular fibrillation (VF)/ventricular tachycardia (VT) (58.3%), asystole (21.7%), electromechanical dissociation (EMD) (7.0%) and other (13.0%). Initial success was defined as return of spontaneous circulation (ROSC). This was achieved in 75.0% of all resuscitation attempts. Within the VF/VT group, successful outcome remained consistent over the 4-year period with an ROSC of 85%. Successful outcome remained consistent in the EMD group, however, the number of arrests was small. Within the asystole group, initial survival increased from 47.5% in 1993-1994 to 67.5% in 1995-1996. These results suggest that BLS and ALS training may only have an impact on initial survival from cardiac arrest.     

Resuscitation from prolonged cardiac arrest with high-dose intravenous magnesium sulfate

We present evidence of resuscitation from prolonged (70-min) cardiac arrest, temporally associated with administration of 8 g intravenous (IV) magnesium sulfate (MgSO₄). A patient undergoing liposuction surgery developed bradycardia and a fall in oxygen tension after reversal of general anesthesia with physostigmine. The electrocardiogram (ECG) rhythm degenerated to ventricular asystole, which was refractory to standard therapy, including multiple boluses of epinephrine, atropine, wide-open dopamine, and attempts at right heart pacing. External cardiopulmonary resuscitation (CPR) was continuously maintained with the patient intubated on 100% oxygen. Multiple electric countershocks (× 7) and lidocaine were also administered when ventricular tachycardia/ventricular fibrillation (VTNF) occurred, but without clinical success. Approximately one hour into the resuscitation, after all of the above occurred, 8 g IV MgSO₄ was given and countershock repeated. Whereas the 7 previous countershocks had resulted in unsuccessful conversion of VT/VF to a pulseless rhythm (END), the 8th countershock (applied immediately after two 4 g boluses of IV MgSO₄) resulted in a stable pulse and normal sinus rhythm developing within 4 minutes. The patient recovered without neurologic deficit.     

The Changing Incidence of Ventricular Fibrillation in Milwaukee,Wisconsin (1992–2002)

Objectives. To investigate the changes in annual incidence andsurvival of out-of-hospital cardiac-etiology arrests of different initial rhythms, particularly ventricular fibrillation (VF) andventricular tachycardia (VT), among adults (> 21 years old) in Milwaukee County between 1992 and2002 andestablish correlations with patient andemergency medical services (EMS) system-dependent factors. Methods. The study was a retrospective, observational study of all adult (> 21-year-old) patients with out-of-hospital cardiac-etiology arrests with identifiable rhythm andresuscitation attempted by the Milwaukee County EMS system from 1992 to 2002. Nine thousand one hundred seventy cases were enrolled. Primary outcome measures were changes in annual incidence of initial cardiac arrest rhythm, with a focus on VF/VT. Secondary outcome measures were changes in survival to hospital admission andhospital discharge for VF andVT. Patient andEMS system factors potentially affecting the outcome measures were identified andmodeled using multivariate logistic regression. Results. The incidence of out-of-hospital VF/VT arrests decreased steadily from 37.1 per 100,000 in 1992 to 19.4 per 100,000 in 2002. While the incidences of pulseless electrical activity andoverall cardiac arrest remained unchanged, the incidence of asystole during the study period increased from 27.3/100,000 to 44.9/100,000. Multivariate regression analyses revealed that age < 80 years, male gender, white race, previous cardiac surgery, andcardiac history were patient-dependent factors predictive of VF/VT. Witnessed arrest, public location, andshorter response time were EMS system-dependent factors predictive of VF/VT. Based on observed trends, none of these correlated factors could explain the decrease in the incidence of VF/VT arrests. Rates of patient survival to hospital admission anddischarge were not significantly changed over time. EMS system factors predictive of survival to admission anddischarge were witnessed arrest, public location, anddecreased number of defibrillations. Prior cardiac surgery andabsence of chronic problems were the only patient factors predictive of survival to hospital admission but were not significantly related to survival to hospital discharge. Conclusions. The incidence of out-of-hospital cardiac arrests in adult patients with presenting rhythm of VF/VT declined, while an increase in asystole occurred. This was not explained by any patient or EMS system-dependent factor. Rate of survival for VF/VT arrest did not significantly change over time. Survival was primarily influenced by EMS system factors andunrelated to patient-dependent factors.     

Value of Heart Rate Variability Parameters for Prediction of Serious Arrhythmic Events in Patients with Malignant Ventricular Arrhythmias

Heart rate variability (HRV) assesses the electrical stability of the heart and can identify patients at risk of sudden cardiac death (SCD). The value of 10 HRV parameters from 24 hour ECG (in both time and frequency domain) to predict serious arrhythmic events (SAE) in a group of 56 patients with ventricular tachycardia and/or ventricular fibrillation of different etiologies not due to acute myocardial infarction was explored. Eighteen patients had low left ventricular ejection fractions (LVEF). During follow-up (6–46 months, mean = 24) 8 SCD and 12 recurrences of malignant ventricular arrhythmias or ICD discharges were recorded. Proportional hazard analysis (Cox model) for SAE revealed that the mean of all 5 minute standard deviation of RR intervals (SD) and the amplitude of low frequency spectrum (L) were independent risk factors of SAE (P < 0.05). The best models were: SD+EF and L+EF where predictive values were high (sensitivity approximately 60%, specificity over 95%, positive predictive value over 90% and negative predictive value approximately 80%). Event-free survival curves revealed a significantly shorter survival in patients with EF < 40%: 47% vs. 92%, SD < 43 ms; 56% vs. 92% and L < 16 ms; 56% vs. 89% (all P < 0.001) after 2 years. The subgroup with low EF and SD < 43 ms revealed a significantly shortened survival (27% vs 83% at 2 years, P < 0.01). Some HRV parameters, SD from the time and L from the frequency domain, were predictive of a fatal outcome in VT/VF patients. Combined SD +EF and L +EF values are powerful predictors of serious arrhythmic events.     

End Tidal CO2 Is a Quantitative Measure of Cardiac Arrest

SEHRA, R., et al.: End Tidal CO₂ Is a Quantitative Measure of Cardiac Arrest. Purpose of the study: Predictors of severity of cardiac arrest or efficacy of cardiopulmonary resuscitation are few. Respiratory end tidal CO₂ (ETCO) is a marker of pulmonary blood flow and, possibly, cardiac arrest. The purpose of this study was to evaluate ETCO as a quantitative marker of cardiac arrest in a human model of ventricular fibrillation (VF). Methods: Thirty-one cardiac arrest/VF episodes (mean BP < 40 mmHg) in 8 men and 3 women mean age = 42 ± 24 years, mean left ventricular ejection fraction = 39%) undergoing defibrillator (ICD) implant for ventricular tachycardia or previous cardiac arrest were evaluated with continuous ETCO monitoring during defibrillation threshold testing. All patients but one were intubated. Results: Significant differences   (P < 0.001)   were noted between ETCO values prior (mean 37.2 ± 6.8 mmHg) versus during VF (mean 27.1 ± 5.9 mmHg), and during VF versus return of spontaneous circulation (mean 36.6 ± 6.6 mmHg). ETCO decreased by 23%± 8% from pre-VF to during VF. It increased by 37%± 16% during VF to return of spontaneous circulation. These changes were significantly different   (P < 0.001)   . Conclusion: Significant changes in ETCO were measured during VF arrest. ETCO can predict acute cardiac arrest in a quantitative manner. (PACE 2003; 26[Pt. II]:515–517)     

A model of survival following pre-hospital cardiac arrest based on the Victorian Ambulance Cardiac Arrest Register

AIMS: This study describes the epidemiology of sudden cardiac arrest patients in Victoria, Australia, as captured via the Victorian Ambulance Cardiac Arrest Register (VACAR). We used the VACAR data to construct a new model of out-of-hospital cardiac arrest (OHCA), which was specified in accordance with observed trends. PATIENTS: All cases of cardiac arrest in Victoria that were attended by Victorian ambulance services during the period of 2002-2005. RESULTS: Overall survival to hospital discharge was 3.8% among 18,827 cases of OHCA. Survival was 15.7% among 1726 bystander witnessed, adult cardiac arrests of presumed cardiac aetiology, presenting in ventricular fibrillation or ventricular tachycardia (VF/VT), where resuscitation was attempted. In multivariate logistic regression analysis, bystander CPR, cardiac arrest (CA) location, response time, age and sex were predictors of VF/VT, which, in turn, was a strong predictor of survival. The same factors that affected VF/VT made an additional contribution to survival. However, for bystander CPR, CA location and response time this additional contribution was limited to VF/VT patients only. There was no detectable association between survival and age younger than 60 years or response time over 15min. CONCLUSION: The new model accounts for relationships among predictors of survival. These relationships indicate that interventions such as reduced response times and bystander CPR act in multiple ways to improve survival.     

The autonomic nervous system and ventricular arrhythmias in myocardial infarction and heart failure

Ventricular arrhythmias (VA) can range in presentation from asymptomatic to cardiac arrest and sudden cardiac death (SCD). Sustained ventricular tachycardias/ventricular fibrillation (VT/VF) are a common cause of SCD in the setting of myocardial infarction (MI) and heart failure. A particularly arrhythmogenic cardiac syncytia in these conditions can be attributed to both sympathetic activation and parasympathetic dysfunction, while appropriate neuromodulation has the potential to reduce occurrence of VT/VF. In this review, we outline the components of the autonomic nervous system that play an important role in normal cardiac electrophysiology and function. In addition, we discuss changes that occur in the setting of cardiac disease including adverse neural remodeling and neurohormonal activation which significantly contribute to propensity for VT/VF. Finally, we review neuromodulation strategies to mitigate VT/VF which predominantly rely on increasing parasympathetic drive and blockade of sympathetic neurotransmission.     

Primary Prevention Implantation of Cardioverter Defibrillator without Defibrillation Threshold Testing: 2-Year Follow-up

Background: Even though the intraoperative threshold testing of the implantable cardioverter defibrillator ( ICD ) may cause hemodynamic impairment or be unfeasible, it is still considered required standard practice at the time of implantation. We compared the outcome of ICD recipients who underwent defibrillation threshold testing (DFT) with that of patients in whom no testing was performed.
Methods: A total of 291 subjects with ischemic dilated cardiomyopathy received transvenous ICDs between January 2000 and December 2004 in five Italian cardiology centers. In two centers, DFT was routinely performed in 137 patients (81% men; mean age 69 ± 9 years; mean ejection fraction 26 ± 4%) (DFT group), while three centers never performed DFT in 154 patients (90% men; mean age 69 ± 9 years; mean ejection fraction 27 ± 5%) (no-DFT group).
Results: We compared total mortality, total cardiovascular mortality, sudden cardiac death (SCD), and spontaneous episodes of ventricular arrhythmia (sustained ventricular tachycardia, VT, and ventricular fibrillation, VF) between these groups 2 years after implantation (median 23 months, 25th–75th percentile, 12–44 months). On comparing the DFT and no-DFT groups, we found an overall mortality rate of 20% versus 16%, cardiovascular mortality of 13% versus 10%, SCD of 3% versus 0.6%, VT incidence of 8% versus 10%, and VF incidence of 6% versus 4% (no significant difference in any comparison).
Conclusions: No significant differences in the incidence of clinical outcomes considered emerged between no-DFT and DFT groups. These results should be confirmed in larger prospective studies.     

Postcountershock pulseless rhythms: hemodynamic effects of glucagon in a canine model

Defibrillation after prolonged ventricular fibrillation (VF) is frequently followed by asystole or electromechanical dissociation (EMD) which are usually fatal. We studied the effects of glucagon, a known inotropic and chronotropic agent, during 19 episodes of postcountershock asystole/EMD in nine dogs. Systolic and diastolic aortic (Ao), left ventricular, pulmonary arterial, and right atrial (RA) pressures were recorded as was the instantaneous Ao-RA difference (coronary perfusion pressure) and coronary sinus blood flow (CSF) during closed-chest CPR. VF was induced electrically; 2 min later, a 400-J transthoracic shock was given. Countershock was always followed by asystole (n = 12) or EMD (n = 7). Conventional closed-chest CPR with a mechanical device was begun 30 to 60 sec after countershock and continued for 2 to 3 min. If a perfusing rhythm did not occur, glucagon (1 mg) was given iv and CPR continued for 2 to 3 min more. Glucagon had no significant effect on intravascular pressures, the coronary perfusion gradient, or CSF when compared to CPR alone. However, in 14 or 19 postcountershock episodes unresponsive to CPR alone, glucagon restored effective spontaneous circulation, i.e., successful cardiac resuscitation, due to its effects on the intrinsic pacemaker discharge rate. Glucagon has been previously shown to stimulate myocardial adenyl cyclase via nonadrenergic mechanisms. We conclude that when postcountershock asystole/EMD occurs, glucagon has a direct and favorable effect on cardiac resuscitation outcome due to its effects on pacemaker discharge rate which is not mediated by changes in myocardial blood flow or coronary perfusion pressure.     

植入型心律转复除颤器的临床应用及随访观察

目的 :观察我院 8例次植入型心律转复除颤器 (implantablecardioveterdefibrillatorICD)患者的临床疗效及随访情况。方法 :自 1996年 7月至 2 0 0 3年 9月 ,共有 7例患者 (其中 1例更换 1次 )在我院成功安装了ICD。 4例为扩张型心肌病 ,1例为长QT间期综合症 ,1例为多形性室性心     

Resuscitation by primary care doctors

BACKGROUND: Sudden cardiac arrest is a common mechanism of premature death in the community. Resuscitation is often possible, but no large study of resuscitation by doctors who practice there has been published. METHODS: General practitioners (GPs) equipped with defibrillators reported 555 patients with cardiac arrest in whom they attempted resuscitation. FINDINGS: Average age was 65.4, 75% male. Most arrests (49%) occurred at the patient's home but some (18%) occurred at or near the doctors' surgeries. Heart disease was responsible for 88% of the arrests: in these cases resuscitation to leave hospital alive was frequently successful (148 of 436 attempts, 34%). Success was rare (one of 59, <2%) when the arrest was due to non-cardiac disease. Resuscitation was most common when the first monitored rhythm was shockable (VF/VT) and defibrillated promptly: 144 out of 351 (41%) patients surviving. VF/VT was most common with early rhythm monitoring, particularly when the doctor was present (63% survival), or nearby (54%). When VF/VT complicated AMI, 72% of those defibrillated within 1min of onset survived. With delayed attendance, the frequency of VF/VT fell and asystole or Pulseless Electrical Activity (PEA) became more common. Survival after resuscitation was rare for patients presenting with these rhythms: five of 202 (2.5%). No such patient survived unless the rhythm could be converted to VF/VT with drugs or basic life support and subsequently shocked. CONCLUSION: Primary care doctors equipped with defibrillators attend patients with cardiac arrest under circumstances in which resuscitation is frequently successful. This presents a unique opportunity to reduce mortality from sudden cardiac arrest.