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PubMed2003

[Interferences in the everyday life of the patient with a cardiac pacemaker or an implantable defibrillator].

The electromagnetic sources of interferences being able to deteriorate the operation of cardiac pacemakers or implantable defibrillators are numerous. This potential risk has been known since the release, 40 years ago, of pacemakers incorporating a detection circuit. Many papers, reviewed in this article, have been published about these conflicts. In daily practice, the risk of dangerous interference is weak, but it seems obvious that the implantable defibrillators are much more sensitive to the external environment than the cardiac pacemakers. With some precautions to eliminate manifest risk situation, it is possible to carry out a strictly normal life. Diagnostic memories increasingly sophisticated included in the new prostheses make possible the identification of asymptomatic conflicts, and the specification of the mechanism of a real problem. Provided information may also be useful to find solutions (adjustment, precautions) to decrease, even to remove the risks.

Defibrillators, Implantable↗
PubMed1998

Myocardial lactate extraction during repeated fibrillation/defibrillation episodes in defibrillator implantation testing.

Intraoperative testing with several fibrillation/defibrillation episodes (FDEs) is routinely performed during defibrillator implantation. Testing is considered safe even in patients with severe cardiac impairment, provided the recovery timespans and number of FDEs are adapted to the individual patient. Myocardial lactate extraction (MLE) was examined in two testing protocols. In 30 patients with coronary artery disease defibrillator implantations were performed under intravenous anesthesia. A percutaneous catheter was positioned into the coronary sinus (CS) underfluoroscopy. Two groups were randomly formed: group A (n = 20, mean number of FDEs: 4.2/patient) with 2 minutes waiting time between FDEs, and group B (n = 10, mean number of FDEs 4.1/patients) with 10 minutes between FDEs. Defibrillation pulses were released 15 seconds after T wave shock induced fibrillation. To estimate MLE, arterial and CS blood samples were collected before and after each FDE. After the last FDE, samples were obtained after 5, 10, and up to 20 minutes. In group A, MLE fell from a baseline value of 29.6% +/- 3.6% before the FDEs to 7.8% +/- 5.4% immediately after the episodes. MLE recovered to 27.2% +/- 6.5% within 1 minute and overshot to 35.6% +/- 5.8% within 5 minutes. In group B, MLE decreased from 37.6% +/- 7.5% to 15.1% +/- 8.1% immediately after each FDE and rose to its original value (33.6 +/- 7.8) within the 5-minute recovery period. MLE decreased immediately after each FDE, and recovered within 1 minute even in poor left ventricular function. For full MLE recovery a 2-minute wait between episodes is sufficient, if the total number of FDEs does not exceed four.

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PubMed1999

Relationship between shock energy and postdefibrillation ventricular arrhythmias in patients with implantable defibrillators.

BACKGROUND: The relationship between postdefibrillation ventricular arrhythmias and shock strength is poorly understood in patients with implantable defibrillators. The purpose of this study was to characterize the relationship between postdefibrillation ventricular arrhythmias and shock strength. METHODS AND RESULTS: Forty-three patients with an implanted defibrillator underwent six separate inductions of ventricular fibrillation (VF) after a step-down defibrillation energy requirement (7.3 +/- 4.6 J) was determined. For each of the first three inductions of VF, the first two shocks were low energy and equal to approximately 75% of the defibrillation energy requirement (5.4 +/- 3.3 J), or to the defibrillation energy requirement plus 10 J (17.5 +/- 4.3 J). After the first two shocks, subsequent shocks were programmed to the maximum available energy (29.0 +/- 2.5 J). The alternate technique was used for the subsequent three inductions of VF. Postdefibrillation ventricular arrhythmias were noted. Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a low-energy shock (19%), than after a high-energy shock (1.5%; P = 0.005). Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a high-energy shock (32%), than after a low-energy shock (7.1%; P = 0.002). A relationship between the cycle length of the postdefibrillation ventricular arrhythmias and the absolute defibrillation energy was observed (P < 0.001; r = 0.6), and ventricular arrhythmias with a cycle length > 300 msec were uncommon after shocks < or = 10 J (P = 0.001). The characteristics of ventricular arrhythmias after maximum-energy shocks were similar to those that occurred after high-energy shocks. CONCLUSIONS: Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec are more common after shocks of strength associated with a low probability of successful defibrillation. Postdefibrillation ventricular arrhythmias with a cycle length of > 300 msec are more common after high- and maximum-energy shocks, and are directly related to the absolute defibrillation energy.

Cardiomyopathies↗
PubMed2001

Dual-coil vs single-coil active pectoral implantable defibrillator lead systems: defibrillation energy requirements and probability of defibrillation success at multiples of the defibrillation energy requirements.

AIMS: The aim of the study was to compare the defibrillation energy requirements and the probability of successful defibrillation at multiples of the minimum defibrillation energy requirements in active pectoral implantable defibrillators with single- and dual-coil lead systems. METHODS AND RESULTS: Eighty-three consecutive patients undergoing implantation of an active pectoral cardioverter-defibrillator were randomized to receive a dual- or single-coil lead system. Defibrillators of two manufacturers with a fixed tilt biphasic defibrillation waveform were used. Defibrillation energy requirements were determined using a step-down defibrillation testing protocol. According to the randomization protocol, the patients were assigned to three additional consecutive defibrillation attempts during device implantation and during pre-discharge testing of either 1.0, 1.5 or 2.0 times the determined defibrillation energy requirement. Patients presenting defibrillation energy requirements > 15 J were excluded from analysis. Eighty of 83 patients (96%) completed the study protocol. Three patients were excluded due to elevated defibrillation energy requirements. The defibrillation energy requirements in the dual- and single-coil patient groups were 8.0 +/- 3.6 J and 8.4 +/- 3.7 J (ns), respectively. A comparable percentage of study patients showed defibrillation energy requirements <10 J (dual-coil: 88% vs single-coil: 83%). Defibrillation impedance was significantly different (dual-coil: 50 +/- 5.8 Ohm; single-coil: 39.8 +/- 4.2 Ohm). Regarding the probabilities of successful defibrillation, there were no significant differences between the two patient groups. The probabilities of defibrillation at the three multiples of the defibrillation energy requirement using a dual- and single-coil lead system were 82, 89.7 and 93.6 and 77.8, 94.1 and 95.8%, respectively (P=0.88, P=0.42, P=0.62, respectively). CONCLUSIONS: Dual- and single-coil active pectoral defibrillator systems show no difference in defibrillation energy requirements and no difference in the probability of successful defibrillation at multiples of the minimum defibrillation energy requirement. The use of more simplified defibrillator lead systems may contribute to a future lead design focusing on improvement in lead durability.

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PubMed1994

[Automatic implantable defibrillators; subdiaphragmatic insertion].

Although the material and techniques of implantation of the electrodes of implantable defibrillators have been improved, the abdominal implantation of the generator remains widely used as described by Mirowski in 1980. Despite a progressive reduction in their size, the generators remain bulky and a source of local complications. The risks and discomfort of implantation in the abdominal wall led the authors to try subdiaphragmatic implantation in 22 patients. There was no morbidity with perfect healing in all 22 cases. The mean follow-up period was 11 months. The patients felt very comfortable, a significant advance with respect to abdominal implantations.

Adolescent↗
PubMed1996

Safety of nurse-administered deep sedation for defibrillator implantation in the electrophysiology laboratory.

UNLABELLED: Implantation of implantable cardioverter defibrillators (ICDs) in the electrophysiology (EP) laboratory has been shown to be safe. However, general endotracheal anesthesia and/or administration of sedatives is mostly performed by anesthesiologists. In 53 patients undergoing ICD implantation in the EP laboratory, we prospectively assessed whether deep sedation without endotracheal intubation can be administered by nursing personnel under medical supervision. The mean patient age was 67 +/- 7 years, and the mean ejection fraction was 32 +/- 8%. All ICDs were placed in the abdomen requiring lead tunneling. Patients were monitored with pulse oximetry and noninvasive blood pressure recordings. The level of consciousness and vital signs were evaluated at 5-minute intervals. Deep sedation was induced with phenergan and midazolam and maintained with either meperidine or fentanyl. The mean doses given were as follows: phenergan 0.33 +/- 0.15 mg/kg, midazolam 0.05 +/- 0.03 mg/kg, meperidine 0.46 +/- 0.10 mg/kg per hour, and fentanyl 1.94 +/- 0.71 micrograms/kg per hour. None of the patients required intubation during or after the procedure. No death occurred and no patient had any recollection of the procedure. In three patients, O2 desaturation was easily managed by transient reversion of the effects of meperidine or fentanyl with naloxone. No patient experienced prolonged hospitalization after the implant (mean 2.4 +/- 0.5 days). IN CONCLUSION: (1) adequate sedation for ICD implantation and testing can be administered safely by nursing staff in the EP lab; (2) optimum sedation protocols should include drugs easy to reverse in case of excessive respiratory depression; and (3) this may represent a more cost-effective approach to ICD implantation.

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PubMed1995

Antiarrhythmics Versus Implantable Defibrillators (AVID)--rationale, design, and methods.

The Antiarrhythmics Versus Implantable Defibrillators (AVID) study compares a strategy of initial treatment with an implantable cardioverter-defibrillator (ICD) to a strategy of initial treatment with an antiarrhythmic drug to prevent death in patients with a history of ventricular fibrillation or hemodynamically compromising ventricular tachycardia, or both. Neither arrhythmia can have been due to a transient or correctable cause. The principle exclusions are a contraindication to amiodarone therapy and inability to undergo ICD implantation. Antiarrhythmic drug therapy includes empiric amiodarone and guided sotalol. The ICDs allowed are advanced generation devices, and most are implanted transvenously. The primary end point of the study is total mortality. Secondary end points are cost and quality of life. The study was designed in 2 phases. The pilot phase enrolled 200 patients between June 1993 and June 1994. Data collected during the pilot phase confirmed that the trial is feasible. An additional 1,000 patients will be enrolled between June 1994 and March 1997. It is anticipated that all 1,200 patients will be followed until September 1998, and will be included in the intention-to-treat analysis.

Amiodarone↗
PubMed2005

Cardioverter-defibrillator implantation in high-risk patients with hypertrophic cardiomyopathy.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are used with increasing frequency in hypertrophic cardiomyopathy (HCM) patients of all ages for primary and secondary sudden death prevention. Concerns may arise regarding the safety of device implantation because of unique clinical and phenotypic expressions of HCM. OBJECTIVES: The purpose of this study was to assess the efficacy and safety of ICD placement in high-risk patients with HCM. METHODS: We analyzed the experience with ICDs and transvenous lead systems in 75 consecutive HCM patients at the Minneapolis Heart Institute from 1993 to 2004. RESULTS: The age of the study group patients was 12 to 79 years (mean 36 +/- 16). Patients received ICDs for secondary (n = 4, after cardiac arrest) or primary prevention (n = 71, with > or = 1 risk factor). Thirty-one patients demonstrated disease features that potentially impacted methodology and safety of the implant procedure, most commonly massive left ventricular (LV) hypertrophy and outflow obstruction > or = 50 mmHg. There were no procedure-related deaths; defibrillator implants were successful and uneventful in 71 of 75 patients (95%). In 3 of the 75 patients (4%), defibrillation was unsuccessful because of high thresholds, associated with extreme hypertrophy (wall thickness > 45 mm) and/or ongoing amiodarone therapy. In two of these patients, thoracotomy with epicardial lead placement achieved successful defibrillation; ICD therapy was abandoned in the other patient. CONCLUSION: ICD placement in children and adults with HCM is generally safe and effective. However, in some patients with massive LV hypertrophy and/or prior administration of amiodarone, transvenous defibrillation proved difficult, and epicardial lead placement was required. High-energy ICD devices and defibrillation threshold testing are recommended for most high-risk HCM patients.

Adolescent↗
PubMed2005

Implantable defibrillators configured for hybrid therapy of persistent and permanent atrial fibrillation: initial clinical experience with a novel lead system.

AIM: Hybrid therapy strategies have combined antiarrhythmic drugs (AAD) with pacemakers, atrio-ventricular defibrillators (AV ICD) or atrial ablation individually. The feasibility combining AAD with dual site RA pacing (DAP) in an AV ICD has not been examined. METHODS: We used an AV ICD with a novel lead configuration permitting DAP, antitachycardia pacing (ATP) or atrial shocks (ADF) in patients (pts) with refractory persistent or permanent AF. Hybrid therapy included linear RA ablation and/or focal ablation. Continuous DAP and automatic ATP with patient or physician activated ADF. RESULTS: 24 pts, mean age 66 +/- 10 yrs, with cardiac disease (22 pts), underwent insertion of an AVICD with dual RA leads. 20 patients had concomitant ablative procedures (RA only = 19, RA + LA = 1) and all pts continued previously ineffective AAD. During a follow-up of 2-36 months (mean 17 +/- 8 mos), rhythm control was restored in all pts & maintained long-term in 19 (83%) pts. 8 pts used AF termination therapies successfully. Device datalogs showed no episodes of AF in 6 pts, asymptomatic brief arrhythmias in 4 pts, infrequent paroxysmal AF in 9 pts & persistent AF recurred in 5 pts. AV ICD detection algorithms reliably detected AF or AT in the DAP mode in all pts. Intermittent brief P wave double counting occurred during AT in selected pts. No pt received inappropriate ADF therapy. CONCLUSIONS: 1. DAP can be safely incorporated in an AVICD devices for use in an hybrid therapy strategy for AF pts. 2. These devices can be effective for both AF prevention & termination. 3. Long term rhythm control can be achieved and documented by device datalogs in persistent and permanent AF.

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PubMed1987

Intraoperative comparison of sequential-pulse and single-pulse defibrillation in candidates for automatic implantable defibrillators.

Sixteen survivors of cardiac arrest underwent intraoperative comparison of the effectiveness of sequential-pulse and single-pulse defibrillation. Defibrillation was tested alternately with the single-pulse or sequential-pulse technique 10 seconds into an episode of ventricular fibrillation that was induced with alternating current. The sequential-pulse defibrillation technique using truncated exponential pulses was performed with a right ventricular endocardial catheter and a left ventricular epicardial patch electrode. The first pulse was delivered between the right ventricular apical and the superior vena caval electrode on the right ventricular endocardial catheter. The second pulse was delivered between the right ventricular apical electrode and the left ventricular patch electrode 0.2 ms after termination of the first pulse. Single-pulse defibrillation was performed with a standard intracardiac defibrillation system in which a single truncated exponential pulse was delivered across 2 epicardial patch electrodes positioned over the anterolateral right ventricle and the posterolateral left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and integrated to determine delivered energy. Average defibrillation threshold leading-edge voltage for the sequential pulse technique was 496 +/- 140 V, compared with 365 +/- 157 V for the single-pulse technique (p less than 0.005). Defibrillation threshold leading-edge current for the sequential-pulse technique was 6.0 +/- 2.3 A, compared with 10.6 +/- 5.1 A for the single-pulse method (p less than 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

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