Safety and interaction of patients with implantable cardiac defibrillators driving a hybrid vehicle.

BACKGROUND: Electromagnetic interference (EMI) can affect the function of implantable cardioverter defibrillators (ICD). Hybrid electric vehicles (HEV) have increased popularity and are a potential source of EMI. Little is known about the in vivo effects of EMI generated by HEV on ICD. OBJECTIVE: This study evaluated the in vivo interaction between EMI generated by HEV with ICD. METHODS AND RESULTS: Thirty patients (73±9 y/o; 80% male) with stable ICD function were exposed to EMI generated by a Toyota Prius Hybrid®. The vehicle was lifted above the ground, allowing safe changes in engine rotation and consequent variations in electromagnetic emission. EMI was measured (NARDA STS® model EHP-50C) and expressed in A/m (magnetic), Volts/m (electrical), and Hertz (frequency). Six positions were evaluated: driver, front passenger, right and left back seats, outside, at the back and front of the car. Each position was evaluated at idle, 30 mph, 60 mph and variable speeds (acceleration-deceleration-brake). All ICD devices were continuously monitored during the study. The levels of EMI generated were low (highest mean levels: 2.09A/m at right back seat at 30 mph; and 3.5V/m at driver seat at variable speeds). No episode of oversensing or inadvertent change in ICD programming was observed. CONCLUSION: It is safe for patients with ICD to interact with HEV. This is the first study to address this issue using an in vivo model. Further studies are necessary to evaluate the interaction of different models of HEV or electric engine with ICD or unipolar pacemakers.

Safety of wireless capsule endoscopy in patients with implantable cardiac defibrillators.

OBJECTIVES: Wireless video capsule endoscopy (CE) is a new technology that allows visualization of the entire small intestinal mucosa. It is indicated for the evaluation of obscure gastrointestinal bleeding (OGIB) and other disorders of the small intestine. Studies to date suggest that CE is safe and associated with few adverse events. A concern, which has not been studied, is the potential effect of CE on implanted cardiac devices such as implantable cardiac defibrillators (ICD) and other electromedical devices. We previously found CE to be safe in patients with cardiac pacemakers. The primary aim of this study was to evaluate the safety of CE in patients with ICDs who were being evaluated for OGIB. In addition, a secondary aim of the study was to determine whether ICDs had any effect on the images captured by CE. METHODS: Patients referred for the evaluation of OGIB and who also had an ICD were enrolled into the study after informed consent. Five consecutive patients (four females and one male; mean age: 72 yr; range: 60-81 yr) with ICDs were studied. All patients had transvenous endocardial ICDs located in the chest. Prior to CE, patients had a baseline electrocardiogram (ECG) and ICD interrogation. Thereafter, CE was performed in a hospital setting with telemetry monitoring performed simultaneously. A post-procedure ICD interrogation was carried out to evaluate changes in programmed parameters. A cardiologist and ICD nurse specialist together reviewed both the telemetry monitor and the post-procedure ICD interrogation on each patient. When CE studies were reviewed, observations pertaining to technical difficulties and interference with video imaging were documented. RESULTS: No arrhythmia or other adverse cardiac events were noted during capsule transmission. No interference by the ICD on the CE video images was seen. CONCLUSIONS: CE was performed safely in these five patients with ICDs, and was not associated with any adverse cardiac events. ICDs also do not appear to interfere with video capsule imaging.

Safety of capsule endoscopy in patients with pacemakers.

BACKGROUND: Capsule endoscopy, a new technology, allows visualization of the entire small intestinal mucosa. The main indication for capsule endoscopy at present is the evaluation of GI bleeding of obscure origin. Studies to date suggest that capsule endoscopy is safe and is associated with few adverse events. One concern, which has not been studied, is the potential effect of the capsule on cardiac pacemakers and other electromedical devices. The primary aims of this study were to evaluate the safety of capsule endoscopy in patients with cardiac pacemakers who are being evaluated for GI bleeding of obscure origin and to determine whether pacemakers have any effect on the images captured by the capsule endoscope. METHODS: Patients with cardiac pacemakers referred for evaluation of GI bleeding of obscure origin were entered into the study. Before the procedure, an electrocardiogram was obtained, and pacemaker functions were checked. Capsule endoscopy was performed in a hospital setting to allow closer monitoring, instead of the outpatient clinic, which is our routine. Cardiac rhythm was assessed simultaneously during capsule endoscopy with a Holter monitor. Post-procedure pacemaker function was again checked for any disturbance. When the capsule endoscopy studies were reviewed, observations were made with particular reference to technical difficulty or interference with imaging. OBSERVATIONS: Five consecutive patients (4 men, 1 woman; mean age, 73 years, range 56-92 years) with cardiac pacemakers were studied. In all patients, the indication for capsule endoscopy was GI bleeding of obscure origin. A cardiologist and pacemaker nurse specialist reviewed the Holter monitor recordings and evaluated pacemaker function after the procedure for each patient. No arrhythmia or other adverse cardiac event was noted during capsule transmission. No pacemaker-induced interference on the capsule endoscopy images was observed. CONCLUSIONS: Capsule endoscopy appears to be safe in patients with cardiac pacemakers and does not appear to be associated with any significant adverse cardiac event. Pacemakers do not interfere with capsule imaging.

Biventricular implantable cardioverter defibrillator and inappropriate shocks.

A 53-year-old man with nonischemic cardiomyopathy underwent implantation of a biventricular implantable cardioverter defibrillator (ICD) for symptomatic ventricular tachycardia. He received five shocks while attempting to exercise, 48 hours after implantation. Interrogation of the device revealed double counting of ventricular sensed events by the left and right ventricular leads. Shortening the AV delay and AV nodal blockade (beta-blocker) to promote ventricular pacing failed to prevent additional inappropriate ICD discharges. After detailed consideration of all options including AV nodal ablation, we chose to disconnect the left ventricular lead pending availability of newer devices with sensing functions limited to the right ventricular lead. Since then, the patient has not experienced any additional inappropriate discharges.