An unprecedented cause of cardiac resynchronization with defibrillator (CRT-D) malfunction "A beheaded generator assembly".

Cardiac resynchronization with defibrillator (CRT-D) malfunction can be due to various reasons, including wire injury, insulation break, battery problems, or patient factors. Undesired outcomes can be dramatically elevated in those settings, prompting early detection and proper troubleshooting. To diagnose, clinical correlation and device interrogation are vital. However, it is not uncommon to find general troubleshooting options insufficient, as highlighted in this case report. Here, we presented an unusual "head assembly separation," as the main reason for abnormal device parameters.

Ventricular Tachycardia in Ischemic Heart Disease.

Ventricular arrhythmias are a significant cause of morbidity and mortality in patients with ischemic structural heart disease. Endocardial and epicardial mapping strategies include scar characterization channel identification, and recording and ablation of late potentials and local abnormal ventricular activities. Catheter ablation along with new technology and techniques of bipolar ablation, needle catheter, and autonomic modulation may increase efficacy in difficult to ablate ventricular arrhythmias. Catheter ablation of ventricular arrhythmias seem to confer mortality and morbidity benefits in patients with ischemic heart disease.

Incidence and clinical predictors of low defibrillation safety margin at time of implantable defibrillator implantation.

BACKGROUND: Determination of the defibrillation safety margin (DSM) is the most common method of testing device effectiveness at the time of implantation of implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRTD). Low DSM remains a problem in clinical practice. OBJECTIVE: The purpose of this study is to ascertain the incidence and clinical predictors of low DSM and the treatment strategies for low DSM in ICD or CRTD recipients. METHODS: Selected ICD or CRTD recipients from January 2006 to May 2008 who underwent DSM test at the time of implantation were included. Low DSM patients were defined as patients who had a DSM within 10 J of the maximum delivered energy of the device. These patients were compared to patients who had DSM > 10 J. RESULTS: This study included 243 patients. Of these, 13 (5.3%) patients had low DSM, and 230 patients had adequate DSM. Patients with low DSM had a high prevalence of amiodarone use (69% vs 13%, p < 0.01), secondary prevention indications (69% vs 30%, p < 0.01), and a trend toward younger age (51 ± 18 vs 58 ± 15 years, p = 0.08). After adjustment for age and sex, amiodarone use was significantly associated with low DSM. All low DSM patients except one obtained adequate DSM after taking additional steps, including discontinuing amiodarone and starting sotalol, RV lead repositioning, adding a subcutaneous array or shock coil, changing single-coil to dual-coil lead, and upgrading to a high output device. CONCLUSION: The incidence of low DSM patients is low with high-energy devices. Amiodarone use is associated with low DSM, and its discontinuation or substitution with sotalol is one of a variety of available options for low DSM patients.

Electroanatomic localization of a slowly conducting atrioventricular (Mahaim) accessory pathway.

We present a case of a 34-year-old female with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. Electrophysiologic evaluation demonstrated antidromic tachycardia utilizing a right-sided decremental, slowly conducting atrioventricular pathway. Distinct accessory pathway potentials along the length of the bypass tract were sequentially recorded to define the anatomic course of the pathway, as uniquely represented on a three-dimensional electroanatomic map, and to successfully guide catheter ablation.

Optimal Programming of ICDs for Prevention of Appropriate and Inappropriate Shocks.

Expansion of indications for implantable cardioverter-defibrillators (ICDs) has led to a significant increase in the number of patients receiving ICDs and the number of lives saved because of ICD therapy. However, appropriate or inappropriate shocks are frequent and may result in a significant decrease in quality of life in patients with ICDs. Atrial fibrillation with rapid ventricular response, sinus tachycardia, atrial tachycardia or atrial flutter with rapid conduction, and other supraventricular tachycardias are the most common arrhythmias causing inappropriate therapy. Other causes include oversensing of diaphragmatic potentials or myopotentials, T-wave oversensing, double or triple counting of intracardiac signals, lead fractures or header connection problems, lead chatter or noise, and electromagnetic interference. Strategies to reduce inappropriate therapy using device programming rely on the ability to distinguish supraventricular and atrial arrhythmias from ventricular tachycardia. Avoiding therapy for nonsustained ventricular arrhythmias and increasing the role of antitachycardia pacing to terminate ventricular tachycardia are key approaches to reducing shocks for ventricular arrhythmias. Optimal programming holds great promise for decreasing the overall incidence of shock therapy and increasing ICD acceptance.

Ventricular arrhythmias in heart failure patients.

Ventricular arrhythmia represents a significant cause of mortality and morbidity. Its pathophysiologic mechanisms and electroanatomic substrates are slowly being elucidated. Clinical management in patients with heart failure has progressed from antiarrhythmic drugs to device therapy. Catheter ablation is an effective adjunct in the management of ventricular arrhythmia but remains a significant challenge. Advances in robotic and magnetic catheter manipulation may shorten procedural time and increase safety. Incorporation of imaging technologies such as CT, MRI, or ultrasound with electroanatomic mapping can enhance the ability to map and ablate ventricular arrhythmia. Novel imaging modalities may provide rapid characterization of the substrate for ventricular dysfunction and arrhythmia development and the capacity for serial assessment of the disease progression, improving risk stratification for ventricular dysfunction and arrhythmia development and the capacity for serial assessment of the disease progression, improving risk stratification.

Electrocautery-induced ventricular tachycardia and fibrillation during device implantation and explantation.

UNLABELLED: Electrocautery is commonly employed during surgical implantation and explantation of pacemakers and implantable cardioverter-defibrillators (ICDs). Four cases of electrocautery-induced ventricular tachyarrhythmias including ventricular tachycardia (VT) or ventricular fibrillation (VF) during device implantation or explantation are described. METHODS: The incidence of electrocautery-induced VT or VF at Winthrop University Hospital was analyzed over a 5-year period (November 2000 to March 2006). Specific devices, indications for device implantation or explantation, electrocautery configuration, and grounding patch placement were analyzed. RESULTS: Between November 2000 to March 2006, 4,698 devices were implanted and/or explanted at Winthrop University Hospital, of which 4 patients developed electrocautery-induced ventricular tachyarrhythmias. The patients had a mean age of 64+/- 16 years, and mean left ventricular ejection fraction of 34 +/- 9%. Three patients (75%) had severe coronary artery disease with prior myocardial infarction. Three patients (66%) had clinical hypertension. Three patients developed ventricular tachycardia during elective explantation of a malfunctioning device. One patient developed ventricular fibrillation during pacemaker implantation. Prior to each explant, the ICD was programmed off. Patients underwent explantation of a Medtronic Marquis model no. 7230CX ICD, Medtronic Marquis DR no.7274 and Guidant Ventak Prizm 2 model no. 1861. The mean age of explanted devices was 35 +/- 13 months. CONCLUSIONS: This study demonstrates a 0.09% incidence of provoked sustained ventricular tachycardia or ventricular fibrillation requiring external defibrillation during device implantation or explantation. This occurred despite programming off the ICD prior to device replacement, positioning the grounding pad far from the pulse generator and the use of bipolar electrocautery. We hypothesize that direct current energy is delivered to the pulse generator, lead and/or connector and then to the myocardium. Staff should be aware of electrocautery-induced VT or VF during device procedures and be prepared to promptly cardiovert and/or defibrillate VT/VF should this scenario occur.

Incidence and prognosis of pacemaker lead-associated masses: a study of 1,569 transesophageal echocardiograms.

UNLABELLED: Endovascular lead infection is an uncommon but serious problem. Transesophageal echocardiography (TEE) is a useful tool for identification of pacemaker lead vegetations. Additionally, incidental echogenic masses are occasionally identified by TEE. The prognosis and optimal treatment of either suspected lead infection or an incidental mass is poorly understood. OBJECTIVE: The purpose of this study was to examine the incidence and clinical course of pacemaker lead masses. METHODS: A total of 1,569 sequential TEE examinations performed from January 2002 to January 2005 were reviewed. Retrospective chart analysis of patients with a pacing lead-associated mass was performed to review the indication for TEE as well as clinical management. Telephone follow up was also performed. RESULTS: During 125 TEE examinations, pacemaker leads were visualized in the right-sided chambers. Fifteen studies demonstrated an echogenic mass associated with the lead. In 9 of these studies, endocarditis was suspected, and the mass was felt to be a vegetation: 6 were treated with antibiotics alone, with 1 death attributed to a complication of endocarditis (autopsy proven massive pulmonary embolus); 3 patients were treated with lead extraction, both were alive at follow up; 1 patient was lost to follow up after the TEE. Six patients (5%) were found incidentally to have a mass on the pacing lead during TEE: 3 were treated with warfarin; 2 received no specific therapy; and 1 underwent surgical debridement of the lead during valve surgery. All of the patients in this group were alive at follow up, and no significant clinical events attributable to the lead-associated mass were observed. CONCLUSIONS: TEE identified an echogenic mass on 12% of the leads imaged, with 60% having suspected endocarditis. The mortality rate of lead vegetation was 11%. An incidental mass was noted on 5% of the leads, with no significant associated morbidity or mortality observed.

Complete heart block due to lyme carditis.

Lyme carditis is becoming a more frequent complication of Lyme disease, primarily due to the increasing incidence of this disease in the United States. Cardiovascular manifestations of Lyme disease often occur within 21 days of exposure and include fluctuating degrees of atrioventricular (AV) block, acute myopericarditis or mild left ventricular dysfunction and rarely cardiomegaly or fatal pericarditis. AV block can vary from first-, second-, third-degree heart block, to junctional rhythm and asystolic pauses. Patients with suspected or known Lyme disease presenting with cardiac symptoms, or patients in an endemic area presenting with cardiac symptoms with no other cardiac risk factors should have a screening electrocardiogram along with Lyme titers. We present a case of third-degree AV block due to Lyme carditis, illustrating one of the cardiac complications of Lyme disease. This disease is usually self-limiting when treated appropriately with antibiotics, and does not require permanent cardiac pacing.