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PubMed1999

A cumulative meta-analysis of the effectiveness of defibrillator-capable emergency medical services for victims of out-of-hospital cardiac arrest.

STUDY OBJECTIVE: More than 1,000 patients experience sudden cardiac arrest each day. Treatment for this includes cardiopulmonary resuscitation (CPR) and emergency medical services (EMS) that provide CPR-basic life support (BLS), BLS with defibrillation (BLS-D), or advanced life support (ALS). Our previous systematic review of treatments for sudden cardiac arrest was limited by suboptimal data. Since then, debate has increased about whether bystander CPR is effective or whether attention should focus instead on rapid defibrillation. Therefore a cumulative meta-analysis was conducted to determine the relative effectiveness of differences in the defibrillation response time interval, proportion of bystander CPR, and type of EMS system on survival after out-of-hospital cardiac arrest. METHODS: A comprehensive literature search was performed by using a priori exclusion criteria. We considered EMS systems that provided BLS-D, ALS, BLS plus ALS, or BLS-D plus ALS care. A generalized linear model was used with dispersion estimation for random effects. RESULTS: Thirty-seven eligible articles described 39 EMS systems and included 33,124 patients. Median survival for all rhythm groups to hospital discharge was 6.4% (interquartile range, 3.7 to 10.3). Odds of survival were 1.06 (95% confidence interval [CI], 1.03 to 1.09; P <.01) per 5% increase in bystander CPR. Survival was constant if the defibrillation response time interval was less than 6 minutes, decreased as the interval increased from 6 to 11 minutes, and leveled off after 11 minutes (P <.01). Compared with BLS-D, odds of survival were as follows: ALS, 1. 71 (95% CI, 1.09 to 2.70; P =.01); BLS plus ALS, 1.47 (95% CI, 0.89 to 2.42; P =.07); and BLS with defibrillation plus ALS, 2.31 (95% CI, 1.47 to 3.62; P <.01.) CONCLUSION: We confirm that greater survival after sudden cardiac arrest is associated with provision of bystander CPR, early defibrillation, or ALS. More research is required to evaluate the relative benefit of early defibrillation versus early ALS.

Electric Countershock↗
PubMed2002

[Use of semi-automatic defibrillators outside the hospital].

With an annual incidence of 1 to 2@1000 and a rate of survival without complication of 2%, sudden death outside hospital constitutes a serious public health problem in France. Ventricular fibrillation (VF) is responsible for more than three quarters of these deaths. The rate of survival is inversely proportional to the duration of VF making early defibrillation a strong link in the chain of survival. The chances of survival are much greater if the cardio-respiratory arrest occurs with a witness, basic first aid is started rapidly, diagnosis of VF is made quickly and the first shock is delivered as soon as possible. These last two criteria are being met more often since the advent of the semi-automatic defibrillator (SAD) and its availability to first line rescuers. The SAD is a light and compact defibrillator capable of automatic analysis of the electrocardiographic trace, charging if it detects ventricular tachycardia (VT) or VF. By analysing the QRS amplitude, its slope, its morphology, its spectral density and the duration of the isoelectric line, the SAD is capable of recognising VF with a sensibility of 98% and a specificity of 93%. The shock, however, is only delivered with a manoeuvre from the operator. The SAD memorizes both the rhythmic event treated and certain parameters relating to its use. During the last decade, the SAD has benefited from the technological evolutions of the implantable automatic defibrillator, with the introduction of a biphasic shock. The use of a biphasic shock allows reduction in the minimal defibrillation charge and thus lightens the apparatus and increases the number of shocks which the SAD can deliver on a charged battery. In authorizing paramedics by statute to use the SAD, it has been possible to reduce the interval from alert to first delivered shock to 8 minutes although it would be 10 minutes if the medical team was awaited, and to obtain a survival rate without complication of 6.3%. The progress achieved by the use of the SAD in the chain of survival cannot be denied. However, to surpass automatic defibrillation and widen the use of defibrillators to an informed and motivated public would certainly bring our results closer to those obtained in America where the survival rate reaches 30% in the best cases; subject to widespread first aid training for the population.

Automation↗
PubMed2002

Out-of-hospital early defibrillation successfully challenges sudden cardiac arrest: the Piacenza Progetto Vita project.

BACKGROUND: Early defibrillation is the most important intervention influencing survival following sudden cardiac arrest (SCA). In order to improve public access to early defibrillation, in North America several experiences of out-of-hospital early defibrillation by non-medical volunteers have been successfully implemented and demonstrated to improve survival. METHODS: Since 1999, in Piacenza, we have established "Progetto Vita", the first experience of out-of-hospital early defibrillation by non-medical volunteers in a medium-size European city. Thirty-nine semiautomatic external defibrillators were placed in Piacenza, Italy (266,531 inhabitants) and distributed in 12 high-risk locations, 12 lay-staffed ambulances and 15 police-cars. A total of 1285 lay volunteers were trained by the emergency medical system to intervene in all cases of suspected SCA. RESULTS: During the first 15 months, 203 codes for suspected SCA were dispatched; 197 were confirmed SCA. The overall survival was 5.6% (11/197): survival improved from 2.9% (4/134) with emergency medical system intervention to 11.1% (7/63) when the "Progetto Vita" was activated (p < 0.05). The survival rate on "shockable" rhythm was 43.7% in the group of patients treated by volunteers vs 16.6% in those treated by emergency medical system aid (p = 0.05). CONCLUSIONS: The widespread use of semiautomatic external defibrillators allows early defibrillation by non-medical volunteers and more than triples the survival rate following out-of-hospital SCA.

Electric Countershock↗
PubMed1992

[Clinical and echocardiographic evaluation of the effects of atrial defibrillation in patients with idiopathic cardiomyopathy].

To elucidate the effects of atrial defibrillation in patients with idiopathic cardiomyopathy, we clinically and echocardiographically assessed 6 patients with hypertrophic cardiomyopathy (HCM) and 7 patients with dilated cardiomyopathy (DCM). Their mean age was 57 +/- 14 years and the mean duration of their atrial fibrillation (Af) was 47 +/- 29 days. There were no differences in age and the duration of Af between the HCM and DCM groups. We assessed the effects of defibrillation on the NYHA functional classification, heart rate (HR), systolic blood pressure (S-BP), M-mode echocardiographic data (LVDd, LVDs, %FS, LAD) and transmitral pulsed Doppler echocardiographic findings (peak velocity, time-velocity integral of rapid and atrial filling waves). These indices were obtained before and 52 +/- 22 days after defibrillation, and were compared with each other. 1. HR decreased (HCM: 87 +/- 16-->58 +/- 7/min, DCM: 93 +/- 19-->70 +/- 14/min) and total left ventricular filling increased (HCM: 6 +/- 1-->11 +/- 4 cm, DCM: 6 +/- 1-->10 +/- 2 cm) after defibrillation, and the increment of %FS (HCM: 36 +/- 6-->41 +/- 6%, DCM: 16 +/- 6-->25 +/- 11%) was observed. Four of 6 HCM patients and 5 of 7 DCM patients also improved with regard to the NYHA classification. 2. After defibrillation, LVDd increased in HCM (42 +/- 4-->47 +/- 4 mm), but not in DCM. However, LVDs decreased in DCM (52 +/- 9-->44 +/- 12 mm), but not in HCM. We concluded that atrial defibrillation had a beneficial effect on the recovery of the left ventricular function both in HCM and DCM due to the reduction in HR and increase in left ventricular filling. The mode of LV functional improvement after defibrillation varied depending on the state of patient's basal pathophysiology .

Adult↗
PubMed2003

Automated external defibrillator use among the general population.

Automated External Defibrillators (AED) are becoming more prominent in public locations within the mainstream of our society. They are marketed as providing the ability for a broader range of people, beyond clinicians and community emergency medical services personal, to successfully defibrillate a person in cardiac arrest. The objectives of this study were to determine whether or not a member of the general population, without previous exposure to an AED, could successfully operate an AED, thus delivering the necessary shock in ventricular fibrillation arrest. In addition, we analyzed the relationship between health care training and the time required to defibrillate a patient using an AED and investigated the overall success of operating an AED with respect to health care training. Utilizing an AED trainer, we conducted a timed trial study of five subject categories (general population; first-year dental students; third-year dental students; dentists, hygienists, and nurses; and anesthesiologists and surgeons) as each operator attempted to defibrillate a mannequin (n=50). Their times, success in defibrillation, and comments were recorded. The general population group experienced an 80 percent failure rate, while the other groups showed an inverse relationship between failure rates and the amount of health care training. Overall, only 58 percent of the subjects successfully performed the defibrillation with the AED. Operator speed in relation to the amount of health care training showed another inverse relationship as times decreased from group one (general population) to group five (anesthesiologists and surgeons). The findings suggest that prior exposure to an AED leads to a greater number of successful defibrillations. It remains unclear at this time as to whether a member of the general population can successfully operate an AED.

Analysis of Variance↗
PubMed1991

[Initial clinical experiences with a transvenous-subcutaneous defibrillation system].

In 19 patients with an indication for an implantable defibrillator, it was tried to avoid thoracotomy by using two electrodes positioned via the subclavian vein in the right ventricle (for pacing, sensing, and defibrillation) and the superior vena cava or coronary sinus (for defibrillation), and one electrode positioned subcutaneously near the ventricular apex (for defibrillation). In 17 patients (89%) the transvenous-subcutaneous leads were implanted, whereas in the remaining two patients an epi-/pericardial lead system was subsequently used due to an insufficient defibrillation threshold. Perioperatively, no major complications were observed and patients were rapidly mobilized. Within a follow-up period of 7 +/- 4 months, no malfunction of the lead system became evident. Sixty-eight episodes of spontaneous ventricular tachyarrhythmias occurred, all of which were successfully terminated. In one patient an infection of the lead system developed after 2 months that proved refractory to antibiotics and required surgical removal. Thus, transvenous-subcutaneous placement of leads for implantable defibrillators yielded a sufficient defibrillation threshold in the majority of patients. Long-term efficacy was excellent and no malfunctions were observed. This approach seems to be feasible and advisable in patients with an increased risk for thoracotomy.

Adolescent↗
PubMed1991

Pericardial influence on internal defibrillation energy requirements.

There is no consensus regarding optimal positioning of patch leads for implantation of automatic implantable cardioverter defibrillators. We compared the energy (in joules) required for 50% and 80% successful termination of ventricular fibrillation with titanium-mesh patch leads outside intact normal pericardium and directly on the epicardium in 13 open-chest dogs. Talc was then instilled into the pericardial space to stimulate adhesion formation and pericardial thickening. After 3 weeks of recovery, thoracotomy and defibrillation testing were repeated in nine dogs with the patch leads outside the thickened, adherent pericardium. There were no significant differences in defibrillation energy requirements between locations (p greater than 0.10). In addition, a comparison of electrical impedance measurements at 10 joules showed no significant differences (p greater than 0.30). In this animal model, defibrillation energy requirements were not altered by positioning the patch leads outside normal intact pericardium rather than placing them directly on the epicardium. Furthermore, thickened, adherent pericardium interposed between the patch leads and the heart does not increase defibrillation energy requirements. These data suggest that placement of automatic implantable cardioverter defibrillator patch leads outside the pericardium in patients (including those with pericardial adhesions from previous cardiac operations) will not adversely affect defibrillation efficacy and thus can simplify the implantation procedure.

Animals↗
PubMed1989

Surgical decisions in the management of sudden cardiac death and malignant ventricular arrhythmias. Subendocardial resection, the automatic internal defibrillator, or both.

Subendocardial resection and implantation of an automatic implantable cardioverter/defibrillator are the current preferred treatments for the management of drug-resistant malignant ventricular arrhythmias and sudden cardiac death. We reviewed retrospectively the case histories of 269 patients who had subendocardial resection and 77 patients who had defibrillator implantation to define clinical characteristics of each group and compare operative and long-term results. All patients treated by subendocardial resection had recurrent sustained ventricular tachycardia as a result of a myocardial infarction. From the standpoint of arrhythmia substrate and cardiac disease, patients receiving the defibrillator were a more heterogeneous group. Forty-eight (62%) had coronary artery disease, 28 (36%) cardiomyopathy, and one patient had a primary electrical abnormality. Among patients receiving the defibrillator, 55% had sustained ventricular tachycardia and 45% polymorphic ventricular tachycardia or ventricular fibrillation. Overall ventricular function was similar in the two groups. Operative mortality rate was better in the group having defibrillator implantation (3% versus 15%). Complications related to the defibrillator device or implantation occurred in 46 (60%) patients, with asymptomatic shocks occurring in 35 patients (45%). Since the defibrillator was not designed to prevent arrhythmias, the arrhythmia-free survival rate was much better in the group having subendocardial resection (95% versus 44% at 3 years). Fewer patients treated by subendocardial resection required antiarrhythmic medications (33% versus 66%). The actuarial survival rate was similar in the two groups (approximately 60% at 4 years), with heart failure the most common cause of death. Thus both subendocardial resection and defibrillator implantation are highly effective in preventing sudden cardiac death. The choice of procedure depends on (1) arrhythmia diagnosis, (2) cardiac disease, and (3) intangible factors.

Aged↗
PubMed1988

Bidirectional transvenous/subcutaneous defibrillation of ventricular fibrillation in dogs: success rates, energy requirements, currents, voltages and impedance.

Four hundred and thirteen defibrillations of alternating current-induced ventricular fibrillation were performed in 10 halothane-anaesthetized dogs (body weight: 24.5-30.5 kg). Success rates, energy demands, currents, peak voltages and impedance were determined. A transvenous catheter electrode system (Medtronic 6880, right ventricular apex and superior vena cava, distance 100 or 150 mm) and subcutaneous patch electrodes (Intec 67 L, 2nd/3rd and/or 3rd/4th left intercostal space) were used for bidirectional defibrillation. Loading voltages ranged from 600 to 850 V. With an electrode distance of 100 mm and a pulse duration of 2 ms separated by 1 ms, success rates were 100%, 40% and 0% for 850.650 and 600 V, respectively. With a 3-ms pulse duration, the corresponding rates were 100%, 60% and 50%. With a 2-ms pulse duration, successful defibrillation was achieved with energies lower than 15 J in 27%, with energies between 15 and 20 J in 77%, and 100% with energies higher than 20 J. Defibrillation currents were 4.4-9.3 A for pulse 1 (superior vena cava/ventricular apex) and 6.3-13.4 A for pulse 2 (patch/ventricular apex), respectively. Effective peak voltages ranged from 510 to 787 V and from 514 to 777V and averaged 89.6% of the loading voltages. Impedance values (peak voltage/current) were 75.5-117.7 (pulse 1) and 51.7-94.9 Ohms (pulse 2). Fifty consecutive defibrillations in one animal resulted in a decrease of impedance (114.6 to 84.9 Ohms, pulse 1:75.4 to 53.0 Ohms, pulse 2). Defibrillation of ventricular fibrillation can be achieved with acceptably low energies using a bidirectional transvenous/subcutaneous system, avoiding thoracotomy and general anaesthesia for implantation of the defibrillation system.

Animals↗
PubMed1979

Energy levels and patient weight in ventricular defibrillation.

In a prospective survey employing conventional devices that stored 400 joules or less, direct-current shocks that delivered 194 +/- 11 joules (1.8 joules/kg) to the chest wall terminated 45 of 46 episodes of ventricular fibrillation in 11 of 12 patients weighing 91 to 225 kg. Patients with coronary disease defibrillated more easily than patients without coronary disease. Weight did not determine outcome. The 98% defibrillation efficiency occurred at only half the energy predicted for 50% efficiency from retrospective data. Human defibrillation not only occurred at one third the untested level recommended by proponents of high-energy defibrillation, but also at one fourth the energy, defibrillating 69% of comparably heavy animals. Thus, the costly defibrillators delivering 400 to 800 joules now sold by 11 of 14 American manufacturers are superfluous, untested, potentially lethal devices with which to attempt ventricular defibrillation.

Adolescent↗
PubMedDate not supplied

Treatment of out-of-hospital cardiac arrest with a low-energy impedance-compensating biphasic waveform automatic external defibrillator. The LIFE Investigators.

Few victims of sudden cardiac arrest survive. A new generation of automatic external defibrillators (AEDs), smaller, lighter, easier to use, and less costly, makes the goal of widespread AED deployment and early defibrillation feasible. A low-energy impedance-compensating biphasic waveform allows AED device characteristics more suitable to the goal of early defibrillation than high-energy waveforms. This study observed the performance of such a biphasic waveform in the out-of-hospital setting on 100 consecutive victims of sudden cardiac arrest treated by a wide range of first-responders. AEDs incorporating 150-J impedance-compensating biphasic waveforms were placed into service of 34 EMS systems. Data were obtained from the AED PC data card-recording system. The first endpoint was to determine the effectiveness of this waveform in terminating ventricular fibrillation (VF). The second endpoint was to determine whether or not the use of such an AED culminated in an organized rhythm at the time of patient transfer to an advanced life support (ALS) team or emergency department (ED). The third endpoint was to assess the efficiency of the human-factors design of the AED by measuring user time intervals. The 34 sites provided data from 286 consecutive AED uses, 100 from SCA victims with VF as their initial rhythm upon attachment of the AED. All 286 patients were correctly identified by the AED as requiring a shock (100% sensitivity for the 100 VF patients) or not (100% specificity to the 186 patients not presenting in VF). Times from emergency call to first shock delivery averaged 9.1 +/- 7.3 minutes. A single 150-J biphasic shock defibrillated the initial VF episode in 86% of patients. For all 450 episodes of VF in these 100 patients, an average of 86% +/- 24% of VF episodes were terminated with a single biphasic shock. Of the 449 VF episodes that received up to three shocks, 97% +/- 11% were terminated with three shocks or fewer. The average number of shocks per VF episode was 1.3 +/- 0.7. The average time from AED power-on and pads attached to first defibrillation was 25 +/- 23 sec. At the time of patient transfer, an organized rhythm was present in 65% of the VF patients; asystole was the result in 25%, and VF was in progress in 10%. It is concluded that low-energy impedance-compensating biphasic waveforms terminate long-duration VF at high rates in out-of-hospital cardiac arrest and provide defibrillation rates exceeding those previously achieved with high-energy shocks. Use of this waveform allows AED device characteristics consistent with widespread AED deployment and early defibrillation.

Automation↗
PubMed1997

A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias.

BACKGROUND: Patients who survive life-threatening ventricular arrhythmias are at risk for recurrent arrhythmias. They can be treated with either an implantable cardioverter-defibrillator or antiarrhythmic drugs, but the relative efficacy of these two treatment strategies is unknown. METHODS: To address this issue, we conducted a randomized comparison of these two treatment strategies in patients who had been resuscitated from near-fatal ventricular fibrillation or who had undergone cardioversion from sustained ventricular tachycardia. Patients with ventricular tachycardia also had either syncope or other serious cardiac symptoms, along with a left ventricular ejection fraction of 0.40 or less. One group of patients was treated with implantation of a cardioverter-defibrillator; the other received class III antiarrhythmic drugs, primarily amiodarone at empirically determined doses. Fifty-six clinical centers screened all patients who presented with ventricular tachycardia or ventricular fibrillation during a period of nearly four years. Of 1016 patients (45 percent of whom had ventricular fibrillation, and 55 percent ventricular tachycardia), 507 were randomly assigned to treatment with implantable cardioverter-defibrillators and 509 to antiarrhythmic-drug therapy. The primary end point was overall mortality. RESULTS: Follow-up was complete for 1013 patients (99.7 percent). Overall survival was greater with the implantable defibrillator, with unadjusted estimates of 89.3 percent, as compared with 82.3 percent in the antiarrhythmic-drug group at one year, 81.6 percent versus 74.7 percent at two years, and 75.4 percent versus 64.1 percent at three years (P<0.02). The corresponding reductions in mortality (with 95 percent confidence limits) with the implantable defibrillator were 39+/-20 percent, 27+/-21 percent, and 31+/-21 percent CONCLUSIONS: Among survivors of ventricular fibrillation or sustained ventricular tachycardia causing severe symptoms, the implantable cardioverter-defibrillator is superior to antiarrhythmic drugs for increasing overall survival.

Aged↗
PubMed2002

Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction.

BACKGROUND: Patients with reduced left ventricular function after myocardial infarction are at risk for life-threatening ventricular arrhythmias. This randomized trial was designed to evaluate the effect of an implantable defibrillator on survival in such patients. METHODS: Over the course of four years, we enrolled 1232 patients with a prior myocardial infarction and a left ventricular ejection fraction of 0.30 or less. Patients were randomly assigned in a 3:2 ratio to receive an implantable defibrillator (742 patients) or conventional medical therapy (490 patients). Invasive electrophysiological testing for risk stratification was not required. Death from any cause was the end point. RESULTS: The clinical characteristics at base line and the prevalence of medication use at the time of the last follow-up visit were similar in the two treatment groups. During an average follow-up of 20 months, the mortality rates were 19.8 percent in the conventional-therapy group and 14.2 percent in the defibrillator group. The hazard ratio for the risk of death from any cause in the defibrillator group as compared with the conventional-therapy group was 0.69 (95 percent confidence interval, 0.51 to 0.93; P=0.016). The effect of defibrillator therapy on survival was similar in subgroup analyses stratified according to age, sex, ejection fraction, New York Heart Association class, and the QRS interval. CONCLUSIONS: In patients with a prior myocardial infarction and advanced left ventricular dysfunction, prophylactic implantation of a defibrillator improves survival and should be considered as a recommended therapy.

Adrenergic beta-Antagonists↗
PubMed2004

Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure.

BACKGROUND: We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays. METHODS: A total of 1520 patients who had advanced heart failure (New York Heart Association class III or IV) due to ischemic or nonischemic cardiomyopathies and a QRS interval of at least 120 msec were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy (diuretics, angiotensin-converting-enzyme inhibitors, beta-blockers, and spironolactone) alone or in combination with cardiac-resynchronization therapy with either a pacemaker or a pacemaker-defibrillator. The primary composite end point was the time to death from or hospitalization for any cause. RESULTS: As compared with optimal pharmacologic therapy alone, cardiac-resynchronization therapy with a pacemaker decreased the risk of the primary end point (hazard ratio, 0.81; P=0.014), as did cardiac-resynchronization therapy with a pacemaker-defibrillator (hazard ratio, 0.80; P=0.01). The risk of the combined end point of death from or hospitalization for heart failure was reduced by 34 percent in the pacemaker group (P<0.002) and by 40 percent in the pacemaker-defibrillator group (P<0.001 for the comparison with the pharmacologic-therapy group). A pacemaker reduced the risk of the secondary end point of death from any cause by 24 percent (P=0.059), and a pacemaker-defibrillator reduced the risk by 36 percent (P=0.003). CONCLUSIONS: In patients with advanced heart failure and a prolonged QRS interval, cardiac-resynchronization therapy decreases the combined risk of death from any cause or first hospitalization and, when combined with an implantable defibrillator, significantly reduces mortality.

Adrenergic beta-Antagonists↗
PubMed1999

[Is ICD-programming for double intraoperative defibrillation threshold energy safe and effective during long-time follow-up? Results of a prospective randomized multicenter study (Low-Energy Endotak Trial--LEET)].

The aim of this prospective and randomized study was to evaluate the safety and efficacy of a reduced shock strength in transvenous implantable defibrillator therapy. So far clinical data concerning the safety margin of the shock energy in ICD therapy do not exist. The shock energy tested during long-term follow-up in this study was twice the intraoperatively measured defibrillation threshold (DFT). A total number of 176 consecutive patients representing a typical cohort of ICD patients were evaluated. All patients received a non-thoracotomy lead system (CPI, Endotak 0070, 0090) and a biphasic cardioverter-defibrillator with the ability to store episodes (Cardiac Pacemakers Inc., Ventac TM PRx II, PRx III). The intraoperative defibrillation threshold (DFT) was evaluated in a step-down protocol (15, 10, 8, 5 J) and had to be < or = 15 J for inclusion into the study. The lowest effective energy terminating induced ventricular fibrillation had to be confirmed and was defined as DFT+ augmented defibrillation threshold. The DFT+ value was tested immediately after successful implantation, at discharge, and after a follow-up period of one year. Prior to implantation the patients were randomized into two groups. The energy of the first shock in the study group was programmed at twice DFT+ and in the control group at the maximum energy output (34 J). The efficacy of the first shock and its reproducibility in DFT testings and in spontaneous episodes during long-term follow-up of the study group were compared to those in the control group. A DFT+ value was found to be < or = 15 J in 166 of 176 patients (94%). The DFT+ in the study group was 9.6 +/- 3.2; in control group 10.1 +/- 3.5 J. The prohability of successful defibrillation at DFT+ level after one year was 84%. The success rate of the first shock meant to terminate induced ventricular fibrillation (VF) was 99.5% in the study group (217 of 218 episodes) and 99% in the control group (201 of 203 episodes). During follow-up of 24 +/- 9 months spontaneous episodes in the study group, 83/86 (96.5%) monomorphic ventricular tachycardias (MVT) and 38/40 (95%) VF-episodes were converted successfully by the 2x DFT+ shock. In the control group the first shock was successful in 151/156 (96.8%) spontaneous MVTs and in 30/33 (91%) VF episodes. The efficacy of the first shock was not influenced by clinical data such as the underlying cardiac disease, left ventricular function, ongoing antiarrhythmic therapy with amiodarone, or the number of spontaneous episodes per day or by the DFT itself. At a mean follow-up of two years there was no significant difference between the two groups concerning the incidence of sudden cardiac death (2.4% in the study group vs. 3.8% in the control group). In conclusion programming the first shock with the ICD lead system used in this study at 2x DFT+ is as efficient as a shock energy of 34 J in order to terminate induced and spontaneous episodes of VT/VF. Thus, the safety of ICD-therapy is not impaired when programming the shock energy at the 2x DFT+ value.

Defibrillators, Implantable↗
PubMed2000

[Atrial defibrillators].

The promising results achieved with low-energy, internal atrial cardioversion have stimulated the development of an implantable atrial defibrillator. Initial clinical experience with the Metrix system in a group of highly selected patients with refractory atrial fibrillation (AF) suggests that atrial defibrillation can be performed effectively and safely by using a stand-alone device. The extension of this therapy will depend on the results of further prospective studies comparing this new therapeutic option with other new non-pharmacological methods to treat AF. Internal atrial cardioversion is feasible at low energies with current endocardial transvenous lead configurations primarily designed for ventricular defibrillation. As AF is a frequent arrhythmia in implantable cardioverter defibrillator recipients, the capability for atrial defibrillation has recently been incorporated in a newly designed dual chamber defibrillator (Jewel AF system). Initial clinical experience with this device that combines both detection and treatment in the atrium as well as in the ventricle indicates a significant improvement in the management of patients with both supraventricular and ventricular tachyarrhythmias.

Adult↗
PubMed2005

New technologies of internal defibrillation.

This paper reviews recent research seeking to provide more efficient device oriented treatments for atrial and ventricular fibrillation to improve implantable cardioverter defibrillator (ICD) therapy. Investigators have proposed and tested many innovative technologies that may be included in future ICDs. Amongst the most promising technologies are combined cardiac resynchronization therapy and defibrillation, defibrillation coils in the coronary venous system, critical timing of defibrillation shocks, and pacing during ventricular fibrillation and tachycardia. Atrial defibrillation with ICDs is an area of considerable interest, but is not likely to gain widespread application unless acceptable methods of lowering pain associated with defibrillation shocks are implemented.

Atrial Fibrillation↗
PubMed2006

Is dual defibrillator better than conventional DDD pacing in brady-tachy syndrome? Results of the ICARUS Trial (Internal Cardioversion Antitachypacing and Prevention: Resource Utilization Study).

AIM OF THE STUDY: To compare the impact of dual defibrillator versus conventional DDD pacing on quality of life and hospitalizations in patients with sinus node disease and recurrent symptomatic atrial fibrillation. STUDY DESIGN: Prospective, parallel, controlled trial. METHODS: Sixty-three patients (41 M, mean age 71 +/- 8 years) with sinus node disease and at least three symptomatic episodes of atrial fibrillation during the last year were enrolled. Thirty-one consecutive patients received a dual defibrillator (group A) and 32 standard DDD pacing (group B). In group A, 12 patients received an external remote-control device in order to shock themselves in case of atrial fibrillation, while 19 were scheduled for early in-hospital manual shock. Seventy-five percent had been hospitalized during the last year and 57% had required electrical cardioversion. Atrial fibrillation was persistent in 63.5% and paroxysmal in 37.5%. The follow-up lasted 1 year. RESULTS: Atrial fibrillation recurred in 83.3% in group A and 79.3% in group B (p = ns). Electrical cardioversion was applied in 54.8% in group A and in 21.9% in group B (p < 0.05). On the whole, 89.5% of electrical cardioversions were delivered in the defibrillator group (p < 0.0001). In the whole population 27.0% patients had cardiac-related hospitalization (31.2% in the pacemaker group and 22.6% in the defibrillator group, p = n.s.). In patients with persistent atrial fibrillation, cardiac-related hospitalization rate was significantly lower in the group A (0% vs. 30%, p < 0.05). Considering Symptom Check List, symptoms significantly improved in the whole population, but symptom number and frequency improved significantly only in the group A. Similarly, SF-36 questionnaire scores showed a little higher quality of life improvement in the group A. CONCLUSIONS: Dual defibrillator showed consistent trends toward a higher effectiveness when compared with standard DDD pacing. Dual defibrillator was associated to reduced in-patient cardioversions and to better quality of life. All-cause hospitalizations were reduced only in patients with persistent atrial fibrillation.

Aged↗