Effects of extracorporeal shock wave lithotripsy on tiered therapy implantable cardioverter defibrillators

Pacemakers, implantable cardioverter/defibrillators, and extracorporeal shockwave lithotripsy: evidence-based guidelines for the modern era

Early work examining interactions between extracorporeal shockwave lithotripsy (SWL) and implantable pacemakers or implantable cardioverter/defibrillators suggested that shockwave oversensing may result in inappropriate suppression of pacing, delivery of antitachycardia pacing therapy, delivery of inappropriate shock therapy, or outright damage to such devices. In the absence of national guidelines, those provided by manufacturers are nonuniform and practice patterns vary between centers. Improvements in SWL energy delivery as well as in device shielding and discrimination technologies have demonstrated improved safety data in recent years. We review these advances in both technologies as well as the most recent data to construct practice guidelines for the modern era.

Effects of electromagnetic interference on implanted cardiac devices and their management

Potential interference between implanted cardiac devices such as pacemakers and implantable cardioverter-defibrillators and electromagnetic fields is an important concern for physicians taking care of patients with pacemakers and implantable cardioverter-defibrillators. There are many sources of electromagnetic interference (EMI); however, only a small number of these cause significant problems that need attention. Regardless of its source, EMI is of greater concern for a patient who is dependent on paced rhythm because inhibition of the pacemaker by EMI may produce ventricular standstill. It is important that cardiologists, internists, emergency medicine, critical care physicians, and anesthesiologists be aware of how EMI can affect the function of implanted cardiac devices so that appropriate treatment can be rendered and preventive measures instituted.

Electromagnetic interference in cardiac rhythm management devices

Clinicians caring for cardiac device patients with implanted pacemakers or cardioverter defibrillators (ICDs) are frequently asked questions by their patients concerning electromagnetic interference (EMI) sources and the devices. EMI may be radiated or conducted and may be present in many different forms including (but not limited to) radiofrequency waves, microwaves, ionizing radiation, acoustic radiation, static and pulsed magnetic fields, and electric currents. Manufacturers have done an exemplary job of interference protection with device features such as titanium casing, signal filtering, interference rejection circuits, feedthrough capacitors, noise reversion function, and programmable parameters. Nevertheless, EMI remains a real concern and a potential danger. Many factors influence EMI including those which the patient can regulate (eg, distance from and duration of exposure) and some the patient cannot control (eg, intensity of the EMI field, signal frequency). Potential device responses are many and range from simple temporary oversensing to permanent device damage Several of the more common EMI-generating devices and their likely effects on cardiac devices are considered in the medical, home, and daily living and work environments.

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.

New-generation lithotripters for treatment of patients with implantable cardioverter defibrillator: experimental approach and review of literature

PURPOSE

The influence of shockwaves applied during extracorporeal shockwave lithotripsy on the function of implantable cardioverter defibrillators was evaluated. Mechanical influences as well as proper electrical function were tested in an experimental approach.

MATERIALS AND METHODS

Two implantable defibrillators (Ventak Mini 1743 and AVII 1821) were exposed to the shockwaves of a new-generation lithotripter. Each of the antidysrhythmic devices was tested at several distances from and within the focus of the lithotripter. All studies were performed with maximum energy and the number of shockwaves used for stone treatment. The devices were connected to an ECG simulator, and continuous recording of a surface ECG, a shock ECG, and marker channel was performed.

RESULTS

No macroscopic and microscopic mechanical damage was observed. The detection function of the implantable defibrillators was not altered by any electromagnetic artifacts even when brought into the focus of the shockwaves. All induced ventricular dysrhythmias were terminated properly regarding artifact sensing. However, after defibrillation, the pacing function of the Ventak Mini cardioverter defibrillator, which was programmed into the demand mode, failed. In this case, there was no post-shock pacing in the period of post-defibrillation asystole. The failure was caused by artifact oversensing.

CONCLUSION

In patients with implanted cardiac devices undergoing treatment with a new-generation lithotripter, deactivation of the defibrillator is not mandatory. For safety reasons, continuous ECG recording is recommended. To avoid pacing failure by artifact oversensing, the shockwaves should be applied in a R-wave synchronous mode.

The implantable cardioverter defibrillator

Implantable cardioverter defibrillators (ICDs) have evolved from the treatment of last resort to the gold standard therapy for patients at high risk for ventricular tachyarrhythmias. High-risk patients include those who have survived life-threatening arrhythmias, and individuals with cardiac diseases who are at risk for such arrhythmias, but are symptomless. Use of an ICD will affect the patient's quality of life. Some drugs can substantially affect defibrillator function and efficacy, and possible drug-device interactions should be considered. Patients with ICDs may encounter cell phones, antitheft detectors, and many other sources of potential electromagnetic Interference. In addition to treating ventricular tachyarrhythmias, new defibrillators provide full featured dual chamber pacing, and could treat atrial arrhythmias, and congestive heart failure by means of biventricular pacing.

Cryothermal ablation of the slow pathway for the elimination of atrioventricular nodal reentrant tachycardia

BACKGROUND

We report the first successful slow pathway ablation using a novel catheter-based cryothermal technology for the elimination of atrioventricular nodal reentrant tachycardia (AVNRT).

METHODS AND RESULTS

Eighteen patients with typical AVNRT underwent cryoablation. Reversible loss of slow pathway (SP) conduction during cryothermy (ice mapping) was demonstrated in 11 of 12 patients. Because of time constraints, only 2 sites were ice mapped in 1 patient. Seventeen of 18 patients had successful cryoablation of the SP. One patient had successful ice mapping of the SP, but inability to cool beyond -38 degrees C prevented successful cryoablation. A single radiofrequency lesion at this site eliminated SP conduction. No patient has had recurrent AVNRT over 4.9+/-1.7 months of follow-up. During cryoablation, accelerated junctional tachycardia was not seen and was therefore not available to guide lesion delivery. Adherence of the catheter tip during cryothermy (cryoadherence) allowed atrial pacing to test for SP conduction. Cryoablation in the anterior septum produced inadvertent transient PR prolongation consistent with loss of fast pathway conduction in 1 patient and transient (6.5 seconds) 2:1 AV block in another. On rewarming, the PR interval returned to normal, and the AV nodal effective refractory period was unchanged in both. Accelerated junctional tachycardia was seen on rewarming in both but not during cryothermy.

CONCLUSIONS

Cryothermal ablation of the SP was achieved in patients with this novel technique. Successful ice mapping of both the SP and fast pathway was demonstrated. The ability to test the functionality of specific ablation sites before production of a permanent lesion may eliminate inadvertent AV block.

Radiofrequency catheter ablation of atrial fibrillation initiated by pulmonary vein ectopic beats

Ectopic beats from the pulmonary veins (PVs) have been demonstrated to initiate atrial fibrillation (AF). This article describes the conceptual approach to mapping, interpretation of different electrograms, and ablation of AF initiated by PV ectopic beats.