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PubMed2002

The relative lymphocyte count predicts death in patients receiving implantable cardioverter defibrillators.

Although the survival benefit conveyed by the automatic defibrillator has been well established for several subsets of patients, some patients who receive the device still die early. The relative lymphocyte count (%L), a portion of the white blood cell count differential, which is decreased in states of excess systemic stress, has prognostic value in patients with coronary artery disease and advanced heart failure. This study assessed the association of %L with survival in patients receiving automatic defibrillators. A total of 136 consecutive patients (81% men; mean age 64 +/- 12 years) who were using automatic defibrillators were followed for 29.6 months. The mean ejection fraction was 0.36 +/- 0.17, the mean %L was 22.7 +/- 8%, and 55 (40%) patients had decreased %L (< 20.3%). There were 20 deaths, for a 4-year survival of 71.5%. The association of %L with time to death was assessed by Cox proportional hazards analysis. Ejection fraction (P = 0.005), %L (P = 0.01), and diagnosis (P = 0.03) were independently associated with time to death on multivariate analysis. One-year and 4-year survival rates were 93% and 54%, respectively, for the 55 patients with abnormal %L, compared with 99% and 84%, respectively, for the 81 with normal %L (P = 0.03). This suggests that the %L is a readily accessible prognostic marker in patients using automatic defibrillators. This association is independent of age, sex, diagnosis, and ejection fraction.

Aged↗
PubMed2003

How to program pulse duration or tilt in implantable cardioverter defibrillators.

Implantable cardioverter defibrillators (ICDs) are available with independently programmable duration and tilt of the shock pulse waveform. Manufacturers do not, however, commonly advise how these parameters can be programmed for optimal clinical benefit. From theoretical considerations, the author recommends programming both parameters based on the measured lead system resistance R into which the shock is delivered. Assuming that the defibrillation pulse decline below the defibrillation threshold rheobase is undesirable because of the possibility of refibrillation. Mathematical relationships expressing optimal pulse duration and tilt as functions of the output time constant can be derived that are valid for monophasic pulses and the first phase of biphasic pulses. Two ICD manufacturers provide for programmable tilt (Medtronic GEM III, atrial channel) or both tilt T and pulse duration PD. (St. Jude Medical newest devices). Considering its output capacitance, it is recommended that the Medtronic Gem III should be programmed for T = 50% when R < 75 omega and 65% when R < 38 omega. The author considers programming tilt to 30% or 40% useless in clinical conditions. By the same reasoning, he recommends that the newer St. Jude Medical ICDs should be programmed to T = 50% if R < 75 omega and 60% if R < 41 omega, and PD = 5.5, 5.0, 4.5, 4.0, 3.5, and 3.0 ms for R < 75, 73, 62, 51, 40, and 32 omega, respectively. PD = 6 ms was considered clinically unrealistic. Programmable shock pulse duration and tilt are useful in optimizing defibrillation, but it is suggested that this can best be accomplished by programming these parameters with the guidance of theory as described in this discussion.

Defibrillators, Implantable↗
PubMed2003

Implantation of pacemakers and implantable cardioverter defibrillators in orally anticoagulated patients.

The safety of pacemaker and defibrillator implantations in orally anticoagulated patients using standard techniques has not been thoroughly evaluated. This article describes a prospectively collected experience in such patients. Patients presenting for device implantation who were treated with warfarin were allowed to continue therapy provided that the INR was < 3.5. Implantations involved cannulation of the left axillary vein. Except for defibrillator leads, 7 Fr introducers were used, and all were leads actively fixated. The study included 47 patients who underwent implantation of permanent pacemakers (n = 39), defibrillators (n = 5), or biventricular pacemakers (n = 3). The mean INR was 2.3. The primary indication for anticoagulation was a mechanical cardiac prosthesis in 11 (24%) patients. Atrial fibrillation was present in 33 patients. There were no instances of major bleeding or hematomas requiring evacuation. One patient had a small soft hematoma, which resolved spontaneously. At 6 weeks, all patients had well-healed scars with satisfactory pacing and sensing thresholds. In experienced centers, patients requiring treatment with warfarin may undergo implantation of pacemakers or defibrillators with minimal risk despite continuation of anticoagulation.

Administration, Oral↗
PubMed2003

Nonthoracotomy implantable defibrillator lead extraction: results and comparison with extraction of pacemaker leads.

Extraction of pacemaker leads has been demonstrated to be successful and safe in experienced hands using current tools. Whether application of such techniques and tools yield similar results among patients undergoing extraction of nonthoracotomy implantable defibrillator leads is unknown. This report describes a retrospective analysis of indications, techniques used, and outcome of patients who had a single ventricular nonthoracotomy implantable defibrillator lead extracted at The Cleveland Clinic Foundation. Results were compared to a matched population of patients undergoing extraction of ventricular pacemaker leads from a national registry and to the experience with pacemaker lead extraction at The Cleveland Clinic Foundation. Successful complete extraction of ventricular nonthoracotomy implantable defibrillator leads, in the absence of major complications, was achieved in 96.9% of attempts to extract leads from 161 patients. Clinical success was achieved in 98.1% of patients. Failure occurred in three patients. Two patients had major complications, including one death. The most common indication for extraction was infection (46.6%), followed by lead failure (34.2%). Procedure (140.8 vs 171.2 minutes, P<0.01) and fluoroscopy (9.9 vs 11.0 minutes, P<0.01) times compared favorably with those obtained from the pacemaker lead extraction database. Use of LASER did not influence the safety of the procedure or fluoroscopy times. Extraction of ventricular nonthoracotomy implantable defibrillator leads using currently available tools is a complex but effective procedure. In experienced hands, excellent success rates should be achieved with a low incidence of complications.

Adolescent↗
PubMed2005

Long-term incidence of malignant ventricular arrhythmia and shock therapy in patients with primary defibrillator implantation does not differ from event rates in patients treated for survived cardiac arrest.

INTRODUCTION: Recent trials have demonstrated benefit of prophylactic defibrillator (ICD) implantation compared to conventional treatment in high-risk patients. However, many patients have rare or no sustained arrhythmias following implantation. Our study addresses the question, whether patients with prophylactic defibrillator implantation have a lower risk for life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) compared to sudden cardiac death (SCD) survivors. METHODS AND RESULTS: Over 7 years we enrolled 245 patients. Occurrence of spontaneous sustained VT/VF resulting in adequate ICD treatment was the endpoint. Incidence, type, and treatment of sustained arrhythmia in 43 previously asymptomatic ICD recipients (group B) were compared to data of 202 survivors of imminent SCD (group A). All patients had severely impaired left ventricular ejection fraction (<45%). Group B patients had long runs (>6 cycles, <30 s) of VT during Holter monitoring and inducible sustained arrhythmia. Incidence of rapid VT and VF (cycle length <240 ms/heart rate >250 bpm) after 4 years (35% in both groups, P = ns) and adequate defibrillator therapies (57% vs 55%, P = ns) were similar in both groups after univariate and multivariate analysis. Cumulative mortality tended to be lower in group B compared to group A, but the difference was not statistically significant. CONCLUSION: During long-term follow-up, incidence of sustained rapid ventricular arrhythmia in prophylactically treated patients is as high as that of SCD survivors. Benefit from defibrillator implantation for primary prevention (group B) appears to be comparable to that for survived cardiac arrest (group A).

Adult↗
PubMed2007

[Implantable cardioverter defibrillator: an update].

Automatic implantable cardioverter defibrillator is now a well established therapy to prevent sudden cardiac death. In secondary prevention (patients with a previous cardiac arrest) defibrillator can be considered as a class I indication, if there is no transient or reversible cause. The level of proof is A. in primary prevention the defibrillator is indicated in coronary artery disease patients with or without symptoms of mild to moderate heart failure (NYHA II or III), an ejection fraction lower than 30 %, measured at least one month after a myocardial infarction and 3 months after a revascularisation, surgery or angioplasty (level of proof B). It is also indicated in symptomatic spontaneous sustained ventricular tachycardias with underlying heart disease (level of proof B), in patients with spontaneous sustained ventricular tachycardia, poorly tolerated, without underlying heart disease for which pharmacological treatment or ablation can not be performed or failed (level of proof B). Finally it is also indicated in patients with syncope of unknown cause with sustained ventricular tachycardia or inducible ventricular fibrillation, with an underlying heart disease (level of proof B). The guidelines proposed by the different societies have also proposed class IIa recommendations which are the following: coronary artery disease patients with left ventricular dysfunction (ejection fraction between 31 or 35 %) measured at least one month after a myocardial infarction and 3 months after a revascularisation with an inducible ventricular arrhythmia. It can be also indicated in idiopathic dilated cardiomyopathies with an ejection fraction lower than 30% and NYHA class II or III. It can be also indicated in familial or inherited conditions with a high risk of sudden cardiac death by ventricular fibrillation without any other efficient known treatment and finally in heart failure patients remaining symptomatic, in class III or IV NYHA, with an optimal medical therapy, an ejection fraction lower than 35 % and a QRS complex duration higher than 120 ms: in this case it is an indication of cardiac resynchronization therapy device associated to the defibrillator. All these class IIa indications have a level of proof B.

Aged↗
PubMed2002

Malfunction of endocardial defibrillator leads and lead extraction: where do they meet?

AIMS: The development of new extraction techniques has improved the success rate of intravascular extraction of pacemaker and defibrillator leads, and hence the practice of extraction is expanding. However, the indications for lead extraction of malfunctioning leads in patients with an implantable cardioverter defibrillator (ICD) are still not well established. METHODS AND RESULTS: We reviewed the literature concerning structural complications of ICD leads. The clinical presentation and detection of malfunction is discussed as well as the consequences for adequate defibrillation therapy. An overview of the current published experience of intravascular extraction of ICD leads is provided including a brief discussion of our own experience. CONCLUSION: From this overview we conclude that malfunctioning pace-sense or ICD leads can be left in situ if there are no uncovered insulation defects. Inserting a new pace-sense or ICD lead is preferable in this situation given the current known complication rate of lead extraction. Lead extraction should be reserved for damaged leads in which interference with proper detection or defibrillation of newly inserted leads cannot be excluded.

Arrhythmias, Cardiac↗
PubMed2002

What is the optimal electrode configuration for atrial defibrillators in man?

AIMS: To compare the atrial defibrillation threshold (DFT) for two electrode configurations in patients with drug refractory persistent atrial fibrillation (AF). METHODS AND RESULTS: 11 patients, 73% male, mean age 60.9 (range 38 to 83), underwent implantation of a Medtronic Jewel AF dual chamber defibrillator (model 7250). A step-up atrial DFT was performed in a randomized sequence for two electrode configurations: (1) Right atrial to distal coronary sinus electrode (RA > CS) and (2) defibrillator can to right ventricular and right atrial electrodes (CAN > RV + RA). The RA > CS configuration restored SR in 10 patients (91%). The CAN > RA + RV configuration restored SR in four patients (36%). The mean atrial DFT was significantly lower for the RA > CS than CAN > RA + RV configuration (10 +/- 7 Joules vs 25 +/- 6 Joules), P < 0.01. At 3 months post implantation, AF was reinduced and the protocol was repeated for the optimal electrode configuration. There was no significant difference in the atrial DFT compared with that at implant. CONCLUSION: The right atrium to coronary sinus electrode configuration significantly reduces the atrial DFT. The atrial DFT also remains stable at 3 months post-implantation. Patients with persistent AF undergoing insertion of an atrial defibrillator should have a coronary sinus electrode implanted.

Adult↗
PubMed1995

[Implantable defibrillator in the long QT syndrome].

A 29-year-old otherwise symptom-free patient had undergone a partial thyroidectomy 5 years ago followed by an episode of ventricular tachycardia and (after lidocaine injection) ventricular fibrillation requiring external defibrillation. No cause for the arrhythmias had been found at that time. Two subsequent syncopes led to her hospitalization. An asystole occurred while she was being monitored, and during the resuscitation there were several periods of ventricular fibrillation, which responded to external defibrillation. Subsequently several episodes of self-limiting ventricular tachycardia were recorded. A long QT syndrome with torsade-de-pointes tachycardia was diagnosed on the basis of typical ECG changes (QT interval 545 ms). Extensive diagnostic tests failed to find a cause. To prevent further tachycardias she was given propranolol, 40 mg three times daily, and an automatic defibrillator was implanted as a precaution. But no defibrillator discharge has so far been required (more than 10 months).

Adult↗
PubMed2000

Decreasing the number of leads required for an implantable atrial defibrillator: use of a new 2-lead system.

BACKGROUND: The purpose of this study was to evaluate the use of a new 2-lead system for detection of atrial fibrillation (AF) and atrial defibrillation. METHODS: In 16 patients undergoing elective cardioversion of AF, a 2-lead system was compared with the conventional 3-lead system in a randomized trial. The new 2-lead system consisted of a catheter with a distal bipolar right ventricular electrode pair and a proximal right atrial shock electrode coil and a separate decapolar defibrillation catheter in the coronary sinus. For the 3-lead system, an additional decapolar catheter was placed in the right atrium. AF and sinus rhythm signal amplitude detection and atrial defibrillation threshold (ADFT) were compared in each patient with both systems. RESULTS: Successful defibrillation was obtained in all patients. ADFT for the 2-lead system was significantly higher compared with the 3-lead system (370 +/- 112 vs 316 +/- 100 V, P < .05; 9.3 +/- 5.2 vs 6.8 +/- 4.2 J, P < .05). In contrast, there was an increase in impedance for the 3-lead system (77 +/- 16 ohms vs 68 +/- 13 ohms; P < .05). AF had a lower signal amplitude compared with sinus rhythm for both systems (P < .05), and the 2-lead system had a lower signal amplitude compared with the 3-lead system for both rhythms (P < .05). CONCLUSION: The use of a 2-lead system with this configuration is not superior to the 3-lead system regarding AF signal amplitude detection and ADFT. Further study is needed with implantable-quality leads in place of the temporary catheters used in this study.

Adult↗
PubMedDate not supplied

A survey of first-responder firefighters' attitudes, opinions, and concerns about their automated external defibrillator program.

OBJECTIVE: To identify barriers to first-responder automated external defibrillator (AED) use by determining firefighter attitudes, opinions, and concerns about their AED program. METHODS: An anonymous survey was mailed to all firefighters in a municipal department that had had first-responder defibrillation for more than two years. A follow-up survey was mailed to all nonrespondents. The survey requested firefighter demographics, comfort and experience with AED, definition of DOA (dead on arrival), and opinion of the program. RESULTS: Of 749 firefighters surveyed, 686 responded (92%). The respondents had an average of 12 +/- 8 years of experience; 66% felt very comfortable using the AED and 3% felt very uncomfortable. The respondents had applied an AED to a patient a median of 2 times (range 0-30); 24% had never applied an AED. Eighty-three percent reported they had been on the scene of an out-of-hospital cardiac arrest when their AED was not used for at least one patient. Predominant reasons for not applying an AED included the ambulance arrived "soon enough" (72%), the ambulance arrived first (63%), the patient was DOA (61%), and the patient had a do-not-resuscitate (DNR) order (32%). Eighty-one percent of the respondents correctly listed at least one clinical finding that defines DOA. Ninety-nine percent felt they should continue the AED program. The respondents gave numerous suggestions for improving the program, including being able to visualize the rhythm, increasing their level of care, and improved AED training. CONCLUSIONS: Municipal first response firefighters view their AED program favorably despite infrequently applying an AED. The appropriateness of withholding defibrillation because a secondary response unit will arrive "soon enough" should be reviewed. The definition of DOA should be reviewed to ensure that viable patients are not denied defibrillation.

Attitude of Health Personnel↗
PubMed2004

Defibrillation shock success estimation by a set of six parameters derived from the electrocardiogram.

It is well known that in some cases defibrillator shocks cannot terminate ventricular fibrillation (VF). Repeated failed shocks often may worsen subsequent response to therapy. This study assesses the ability of six parameters derived from the surface electrocardiogram (ECG) to predict defibrillation shock outcome. Using stepwise discriminant analysis, we obtained several discriminant functions, yielding different combinations of sensitivity and specificity for detection of pre-shock ECG segments corresponding to successful versus unsuccessful shocks. The study was performed consecutively for 3, 4 and 5 s ECG time intervals. The prediction accuracy of 72.3% (61.8% sensitivity and 79.6% specificity) with five parameters and 3 s VF segment analysis prior to defibrillation shock could be considered acceptable for possible practical application in automatic external defibrillators.

Databases, Factual↗
PubMed1995

Transvenous defibrillator implantation in patients with persistent left superior vena cava and right superior vena cava atresia.

In this report a transvenous cardioverter defibrillator implantation is described in two patients with a persistent left-sided superior vena cava and right SVC atresia. In the first case, manoeuvring of the guide wire inserted through the left subclavian vein into the SVC proved impossible, revealing a left SVC originating from the left brachiocephalic vein with an acute corner. Changing the side of implantation and inserting a CPI Endotak catheter through the right subclavian vein, the lead was easily advanced through the left SVC into the coronary sinus and then into the right atrium with the tip abutting the lateral atrial wall. Subsequent manoeuvres allowed passage of the tip of the catheter into the right ventricular apex with the proximal defibrillation coil of the Endotak lead in the low left SVC, with its distal limit at the junction with the coronary sinus. A biphasic waveform single pathway RV - > left SVC successfully defibrillated with a stored energy of 5 J. In the second patient, implantation of a transvenous Medtronic system was possible from a left infraclavicular approach. A tripolar RV coil was inserted into the right ventricle via the persistent left SVC and contiguous coronary sinus. Because of the acute angle required to enter the RV in this second case, the RV lead was looped in the right atrium in order to enter the RV in a satisfactory, albeit atypical RV location. This patient was successfully defibrillated with a 5 J monophasic waveform delivered between the RV coil, a CS/left SVC coil, and a subcutaneous patch. In conclusion, both of these patients illustrate the ability to use transvenous ICDs successfully in patients with persistent left superior vena cava although the implantation technique deviates substantially from traditional methods.

Adolescent↗
PubMed1998

Changes in cerebral oxygen uptake and cerebral electrical activity during defibrillation threshold testing.

UNLABELLED: During cardioverter-defibrillator implantation, repeated episodes of ventricular fibrillation (VF) are induced. Insufficient recovery of oxygen metabolism may cause neurological sequelae. In this prospective clinical study, we monitored the electroencephalogram (EEG), middle cerebral artery blood flow velocity (Vmca), and jugular bulb oxygen saturation and estimated cerebral oxygen uptake. Results were analyzed for tests requiring a single shock (Group 1) and tests requiring multiple shocks for defibrillation (Group 2). Immediately after the induction of VF, the mean arterial blood pressure (MAP) decreased to < 30 mm Hg, and the Vmca decreased to 0 cm/s. The EEG showed ischemic changes consisting of a decrease of fast, and an increase of slow, activity, progressively declining to isoelectricity within 11 +/- 2 s. After defibrillation, the MAP recovered rapidly regardless of the arrest duration (3 +/- 2 s). The EEG recovered within 17 +/- 9 and 22 +/- 12 s, respectively, for Groups 1 and 2 (P < 0.05) and did not reveal ischemic changes until induction of a subsequent arrest. In Group 1, the cerebral oxygen uptake increased to 191% +/- 31% of baseline values and returned to baseline in 16 +/- 7 s, whereas in Group 2, it increased to 229% +/- 38% (P < 0.05), followed by a significant decrease to less than baseline (85% +/- 18%; P < 0.005), and returned to baseline simultaneously with the Vmca. We conclude that, although restoration to normal of the EEG and cerebral oxygen uptake coincide in short arrests, EEG recovery underestimates metabolic recovery after tests requiring multiple shocks. IMPLICATIONS: Short test intervals have been mentioned as a cause of neurological sequelae after cardioverter-defibrillator implantation. This study demonstrates that although all systemic hemodynamic variables and the electrocardiogram may have returned to normal, cerebral oxygen uptake may still be depressed for a considerable time, especially after tests requiring two or more shocks.

Adult↗
PubMed2002

Current clinical perspectives on implantable devices for atrial defibrillation.

The role of devices that deliver shock therapy for atrial fibrillation is still debated. Following technical improvements in catheter-based atrial defibrillation, implantable devices have become available either in the form of stand-alone atrial defibrillators or in the form of dual defibrillators. Although preliminary results do not support their use as a single, unique treatment for atrial fibrillation patients, in combination with drugs, pacing or other treatments such as ablation, atrial defibrillators should help appropriately selected groups of patients.

Atrial Fibrillation↗
PubMed2003

Implantable cardioverter-defibrillators in cardiovascular care: technologic advances and new indications.

PURPOSE OF REVIEW: Present generation implantable cardioverter-defibrillators (ICD) have become a proven primary therapeutic option in management of symptomatic ventricular arrhythmias and are now being increasingly used for primary prevention. The addition of biventricular pacing and atrial defibrillation to these devices has had an impact on the management of several new patient populations. The widespread application of these devices requires precise knowledge of their potential benefits and factors that could adversely affect device function. RECENT FINDINGS: ICD therapy has improved the survival of coronary disease patients with left ventricular dysfunction by reducing sudden death rate. In congestive heart failure patients, ICD therapy and biventricular pacing improves heart failure status thus improving overall survival and quality of life. Atrial defibrillation can establish rhythm control in drug refractory atrial fibrillation usually in a "hybrid therapy" prescription. SUMMARY: Implantable cardioverter defibrillators have proven to be invaluable in the primary and secondary prevention of sudden cardiac death. Incorporation of new technology in these devices has resulted in expanded indications that improve survival and quality of life of new patient populations.

Atrial Fibrillation↗
PubMed2006

Implantable devices for management of chronic heart failure: defibrillators and biventricular pacing therapy.

PURPOSE OF REVIEW: With chronic heart failure already an epidemic in the USA, its prevalence is expected to rise significantly in the future. Despite improved survival with pharmacologic therapy, the morbidity and mortality of patients with heart failure remain high. The purpose of this review, therefore, is to present recent data on the non-pharmacologic, device-based treatment of patients with chronic heart failure. RECENT FINDINGS: The implantable cardioverter-defibrillator has become standard treatment for the prevention of sudden, arrhythmic death. Recent well-designed clinical trials have led to device-based therapy as an important component in the management of patients with systolic left ventricular dysfunction (resulting from both ischemic and non-ischemic etiologies) and symptomatic chronic heart failure. Implantable cardioverter-defibrillator therapy alone (without biventricular pacing) results in a significant reduction in the overall mortality of patients with mild and moderate heart failure. Biventricular pacing (or cardiac resynchronization therapy) with or without a back-up implantable cardioverter-defibrillator, compared with optimal pharmacologic therapy, improves symptoms, quality of life, exercise tolerance, left ventricular function, and the survival of patients with advanced heart failure, a left ventricular ejection fraction of 35% or less, and intraventricular conduction delays (QRS > 120 ms), although up to approximately 30% of patients do not respond to cardiac resynchronization therapy. Ongoing and planned studies should clarify which patients are most likely to respond to cardiac resynchronization therapy and elucidate its role in those with a normal (< 120 ms) QRS (approximately 70% of patients with heart failure). SUMMARY: Device therapy (implantable cardioverter-defibrillator and cardiac resynchronization therapy) should be considered an integral, but adjunctive, part of the management of patients with chronic heart failure who are receiving appropriate medical therapy. The type of device used will depend on the individual patient's clinical characteristics.

Chronic Disease↗
PubMedDate not supplied

Erosion of an extrapericardial implantable cardioverter defibrillator patch through the gastric fundus with fistulous tract formation.

Until as recently as the mid-1990s, implantable cardioverter defibrillator (ICD) leads were placed through thoracotomy as anterior and/or posterolateral patches. The defibrillator patches have reportedly been associated with a number of relatively common mechanical complications as well as less common complications, including patch migration or erosion into contiguous structures. We report a previously unreported late complication of epicardial defibrillator patch placement in which patch migration and erosion through the gastric fundus resulted in fistulous tract formation from the mediastinum to the lumen of the stomach. Although surgically implanted epicardial patch defibrillator systems are relatively uncommon in current U.S. practice, these devices are still used when specific anatomic or electrophysiological considerations preclude the use of more common endocardial lead systems. Several thousand patients with epicardial patch leads in place are still believed to be alive in the United States. In these patients, continued vigilance for lead-related complications is appropriate. Prompt surgical intervention is usually warranted when patch migration or complications such as the one described occur.

Defibrillators, Implantable↗