Predictors of intraoperative electrosurgery-induced implantable cardioverter defibrillator (ICD) detection.

BACKGROUND: In the USA, the number of people needing implantable cardioverter defibrillators (ICDs) has grown dramatically. Many ICD recipients will need to undergo a surgical procedure at some point following ICD implantation. Most surgeries involve the use of electrocautery. Currently, the effects of electrocautery-induced electromagnetic interference (EI-EMI) on ICDs are poorly understood. The aim of this study was to study EI-EMI using prospectively collected clinical data. METHODS: We analyzed prospectively collected ICD data from patients undergoing a surgical procedure at Mayo Clinic between 2011 and 2012. Information on clinical, device history, device interrogation pre- and post-surgery, and surgical information were collected for all patients. ICDs were programmed with detections on and therapies off. The patients were then categorized into two groups: those with EI-EMI inappropriate arrhythmia detection and those without detection. The stored electrograms were reviewed. Clinical and device parameters were analyzed to identify predictors of EI-EMI. RESULTS: Of 103 patients studied, bipolar cautery did not induce EI-EMI (0/11 cases), whereas monopolar cautery resulted in noise detection in 11/92 procedures. Among 11 inappropriate episodes of detection, 10 had surgery at chest, neck, and upper extremity sites with cautery current across the ICD lead tip; 1 had abdominal surgery; and none had back or low extremity surgery. On average, the near-field electrogram amplitude values were greater than the far-field amplitude values. CONCLUSIONS: EI-EMI does not occur when bipolar cautery or monopolar cautery is used below the hips with the dispersive ground pad applied to the lower extremities. In contrast to external EMI, EI-EMI may be larger on near-field than far-field electrograms.

Cardiac troponin T in patients with cardiac implantable electronic devices undergoing magnetic resonance imaging.

PURPOSE: Magnetic resonance imaging (MRI) has been safely performed in many patients with cardiac implantable electronic devices (CIEDs) using institution-specific protocols. A potential risk of MRI is myocardial heating and cardiac injury, which might be detectable with cardiac Troponin (cTn). We evaluated this in patients with CIEDs undergoing MRI. METHODS: Prospective data were collected from 2008 to the present in patients with CIEDs undergoing clinically indicated MRI performed under institutional protocol. Cardiac Troponin T (cTnT) levels were drawn both before and 24­36 h after the procedure. The collective data were retrospectively analyzed. RESULTS: MRI exams (n=512) were performed in 398 patients. Of these, there were 348 unique scans with cTnT recorded before and after MRI (median age 68, IQ 56­78; 62%men). cTnT did not significantly change for the group as a whole (0.00±0.056). There were 22 (6.3 %) exams with cTnT change ≥0.002 ng/mL following MRI (range 0.01­0.09 ng/mL). There were no clinically significant events in these patients directly attributable to MR. There were no significant changes in pacing threshold or impedance in the group with elevated cardiac biomarkers. CONCLUSION: There are very few situations where myocardial injury as detected by cTnT in patients undergoing MRI with CIEDs could be detected. No adverse clinical events or functional changes of the device were noted, even in those with increases in cTnT. Our experience supports that MRI can be performed safely for appropriately selected patients under close clinical observation. Proactive monitoring with the present iteration of cardiac biomarkers appears to be of limited utility, but prospective monitoring with high sensitivity assays may be able to detect subclinical myocardial damage.

"Power-on resets" in cardiac implantable electronic devices during magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful monitoring and prespecified conditions. Pacemaker-dependent patients are often excluded, partly because of the potential for "power-on reset" (PoR), which can lead to a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to electromagnetic interference during MRI. OBJECTIVE: The purpose of this study was to review risk factors for PoR during MRI. METHODS: A prospective study was performed between January 2008 and May 2013 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated before and after MRI, programmed to an asynchronous mode or an inhibition mode with tachyarrhythmia therapies turned off, and reprogrammed to their original settings after MRI. RESULTS: MRI scans (n = 256) were performed in 198 patients with non-MRI-conditional CIEDs between 2008 and 2013 (median age 66 years; interquartile range 57-77 years; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than with other generator brands (n = 9/139 vs 0/117 [6% vs 0%]; P = .005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n = 4) and transient anomalous battery life indication (n = 1). All devices functioned normally after MRI. CONCLUSION: PoR occurs infrequently but can cause deleterious changes in pacing mode and heart rate. MRI should not be performed in pacemaker-dependent patients with older at-risk generators. Continuous monitoring during MRI is essential because unrecognized PoR may inhibit pacing or accelerate battery depletion due to high pacing output.

Multicenter study of the safety and effects of magnetic resonance imaging in patients with coronary sinus left ventricular pacing leads.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with left ventricular (LV) leads may cause tissue or lead heating, dislodgment, venous damage, or lead dysfunction. OBJECTIVE: The purpose of this study was to determine the safety of MRI in patients with LV pacing leads. METHODS: Prospective data on patients with coronary sinus LV leads undergoing clinically indicated MRI at 3 institutions were collected. Patients were not pacemaker-dependent. Scans were performed under pacing nurse, technician, radiologist, and physicist supervision using continuous vital sign, pulse oximetry, and ECG monitoring and a 1.5-T scanner with specific absorption rate <1.5 W/kg. Devices were interrogated pre- and post-MRI, programmed to asynchronous or inhibition mode with tachyarrhythmia therapies off (if present), and reprogrammed to their original settings post-MRI. RESULTS: MRI scans (n = 42) were performed in 40 patients with non-MRI conditional LV leads between 2005 and 2013 (mean age 67 ± 9 years, n = 16 [40%] women, median lead implant duration 740 days with interquartile range 125-1173 days). MRIs were performed on the head/neck/spine (n = 35 [83%]), lower extremities (n = 4 [10%]), chest (n = 2 [5%]), and abdomen (n = 1 [2%]). There were no overall differences in pre- and post-MRI interrogation LV lead sensing (12.4 ± 6.2 mV vs 12.9 ± 6.7 mV, P = .38), impedance (724 ± 294 Ω vs 718 ± 312 Ω, P = .67), or threshold (1.4 ± 1.1 V vs 1.4 ± 1.0 V, P = .91). No individual LV lead changes required intervention. CONCLUSION: MRI scanning was performed safely in non-pacemaker-dependent patients with coronary sinus LV leads who were carefully monitored during imaging without clinically significant adverse effect on LV lead function.

Safety and outcomes of magnetic resonance imaging in patients with abandoned pacemaker and defibrillator leads.

INTRODUCTION: Abandoned cardiovascular implantable electronic device (CIED) leads remain a contraindication to magnetic resonance imaging (MRI) studies, largely due to in vitro data showing endocardial heating secondary to the radiofrequency field. We tested the hypothesis that abandoned CIED leads do not pose an increased risk of clinical harm for patients undergoing MRI. METHODS: This single-center retrospective study examined the outcomes of patients who had device generators removed before MRI, rendering the device leads abandoned. Information was gathered through chart review. Data collected included lead model, pacing threshold before MRI, anatomic region examined, threshold data after generator reimplantation, and clinical patient outcome. RESULTS: Patients (n = 19, 11 men and eight women) ranged in age from 19 to 85 at the time of MRI. There was a mean of 1.63 abandoned leads at the time of imaging; none of the leads were MRI conditional. Of the three implantable cardioverter defibrillator (ICD) leads, two of three were dual coil. Most (31/35) of the scans performed were of the central nervous system, including head and spinal imaging. There were no adverse events associated with MRI in any of these patients with abandoned leads within 7 days of the scan. No lead malfunctions or clinically significant change in pacing thresholds were noted with generator reimplantation. CONCLUSION: The use of MRI in patients with abandoned cardiac device leads appears feasible when performed under careful monitoring, with no adverse events, although the experience is small. MRI did not affect the function of leads that were subsequently reconnected to a cardiac device.

A unique case of relapsing polychondritis presenting with acute pericarditis.

Relapsing polychondritis (RP) is an inflammatory disease of the cartilaginous tissue primarily affecting the cartilaginous structures of the ear, nose, joints, and the respiratory system. Cardiovascular complications of RP are associated with high morbidity and mortality and occur most commonly as valvular disease. Pericarditis is a less common complication, occurring in 4% of patients with RP and has not previously been described at presentation. We describe a case of relapsing polychondritis with acute pericarditis at presentation.