Successful ICD Implantation in the Setting of RV Channel Noise

DOI: 10.19102/icrm.2011.020403

JASON RYTLEWSKI, MD, PABLO SAAVEDRA, MD and JEFFREY ROTTMAN, MD

Cardiac Electrophysiology, Vanderbilt Heart and Vascular Institute, Nashville, TN

ABSTRACT. We submit a case of right ventricular (RV) channel electrical noise following upgrade of a dual chamber pacemaker system to a dual-chamber implantable cardioverter-defibrillator (ICD) system. Multiple etiologies of electrical RV channel noise need to be considered when confronted with this clinical situation. In this circumstance, utilization of a chronic RV pacing lead helped to localize the problem source to the newly implanted ICD generator.

KEYWORDS. implantable cardioverter-defibrillator, right ventricular channel electrical noise, pacing.

The authors report no conflicts of interest for the published content.
Manuscript received January 20, 2011, final version accepted March 9, 2011.

Address correspondence to: Jason Rytlewski, MD, 420 Elmington Avenue Apt 104, Nashville, TN 37205. E-mail: jason.a.rytlewski@vanderbilt.edu

Case Report

A 74-year-old man with a history of coronary artery disease status post coronary artery bypass surgery, peripheral vascular disease status post peripheral arterial stenting, carotid artery disease, sick sinus syndrome status post dual-chamber pacemaker implantation, hypertension and hypothyroidism was seen in the arrhythmia clinic for routine follow up. In the clinic, the patient noted symptoms consistent with typical angina, and device interrogation demonstrated an appropriately functioning dual-chamber pacemaker system with generator at elective replacement indicator (ERI). No tachyarrhythmias were recorded. The patient was referred for coronary angiography, which revealed proximal complete occlusions of the left anterior descending artery (LAD), circumflex artery, and right coronary artery (RCA) with a patent left internal mammary artery to LAD, patent saphenous graft to obtuse marginal 1 and brisk LAD collaterals to the RCA. These findings were unchanged from prior catheterization with the exception of increased collateralization of the right coronary arterial system. Repeat transthoracic echocardiography was significant for a decline in left ventricular ejection fraction from a prior value of 50% to 30–35%. Given these findings, intensification of optimal medical therapy was recommended with upgrade of the dual-chamber pacemaker to a dual-chamber intracardiac defibrillator system.

In the electrophysiology laboratory the chronic pacemaker system and leads were dissected from the pocket with the usual methodology. The explanted generator was a Boston Scientific Pacemaker model 1298. The chronic right ventricular (RV) pacemaker lead was a Boston Scientific (St. Paul, MN) model 4457 and the chronic right atrial (RA) pacemaker lead was a Boston Scientific model 4469. Venous access was obtained via modified Seldinger technique and a new Medtronic model 6947-65 lead, reflecting institutional ICD lead preference, was placed within the right ventricle. Interrogation of the lead was unremarkable with an R wave of 7.6 mV, impedance 806 ohms and threshold 0.8 V at 0.5 ms. The chronic pacemaker was then disconnected and the chronic RV pacing lead was capped. A new intracardiac defibrillator generator, St. Jude Medical (St. Paul, MN) model CD-2232, was then attached to the new Medtronic RV lead and the chronic RA lead. Each of the terminal lead pins was visualized to be appropriately positioned within the header, and after torquing set screws the leads passed a “tug test”. The device was placed in the pocket; remote interrogation demonstrated appropriate parameters and function. The pocket was closed with interrupted sutures and the patient was sedated in preparation for defibrillation threshold testing. Immediately prior to induction of ventricular fibrillation, however, unexpected noise was noted in the RV channel as shown in Figure 1. Manipulation of the pocket did not affect this phenomenon. Fluoroscopy demonstrated all terminal pins in appropriate position within the header and the RV intracardic lead position to be unchanged. The pocket was therefore reopened. On inspection there were no visible or palpable defects of the generator or leads. Repeat “tug testing” of the leads confirmed leads to be mechanically secure. The RV lead was removed and retested directly via the programmer analyzer, including manipulation, without noting noise. The lead was reconnected to the header and the device was placed back within the pocket. Identical RV channel electrical noise recurred when flushing the pocket. At this point, the chronic RV Boston Scientific pacemaker lead was uncapped and the lead was connected to the new RV pace/sense port. The electrical noise was again noted on the RV channel as depicted in Figure 2. A new SJM generator model 2231 was attached to the new RV and chronic RA lead with complete resolution of the RV pace/sense noise phenomenon. The pocket was then closed and the device demonstrated appropriate function with defibrillation threshold testing.

Figure 1: unexpected noise was noted in the RV channel.

Figure 2: electrical noise was again noted on the RV channel.

Discussion

This patient case demonstrates several important principles. Intermittent noise on a newly implanted lead is most often from partial contact of the lead terminal electrodes with the head due to incomplete advancement of the lead into the header port or incomplete securing by set screws. Often, electrical noise due to improper pin placement will intensify with physical manipulation. Other possible causes include oversensing of depolarization or repolarization events, diaphragmatic skeletal muscle noise, as may occur with acute lead perforation, lead damage from excessively tightened anchoring sutures, and suturing the lead itself while closing the pocket. Direct retesting of the RV lead by the analyzer and testing of the generator with the normally functioning chronic RV pacemaker lead confirmed that the issue was not related to the new RV lead. Lastly, resolution of the phenomenon with a new generator excluded the possibility of any lead-to-lead interaction. This also excluded problems with interoperability issues (Medtronic ICD lead, St. Jude Generator) although in theory, due to IS-1 and DF-1 standards these interactions should not occur and have not been reported. In our clinical practice, it is not uncommon for an individual to receive a Medtronic lead with a generator from another device company. This is often secondary to either physician or patient preference. As an academic institution, we feel it is vital that electrophysiology fellows are trained and familiar with the various devices from Medtronic, St. Jude Medical and Boston Scientific in order to be prepared to practice in an environment where they may not be able to choose a particular company in the future due to contract agreements. Despite practicing in an era of extremely reliable intracardiac devices, these instruments are becoming progressively more complex, and this case exemplifies why device implanters need to maintain a high level of vigilance regarding device function and programming.