Asirvatham, Samuel J.

RVOT Atypical VariantsBackgroundRight ventricular outflow tract (RVOT) arrhythmias are a common form of ventricular tachycardia (VT) in patients with structurally normal heart. The underlying mechanism is due to triggered activity. Mapping and ablation is relatively straightforward targeting the earliest point of activation. Previously reported causes of difficult ablation in the RVOT region include under recognized right ventricular cardiomyopathy/sarcoidosis, presence of endocavitary structures, close proximity to the coronary vasculature, and origin from non‐RVOT structures.Methods and ResultsWe identified all patients undergoing PVCs/sustained RVOT VT ablation from January 2013 to December 2013. This included 33 patients. Of these, we identified procedures that were considered difficult despite a single morphology arrhythmia being targeted and no underlying cardiomyopathy present. Difficulty was specifically considered when ablation at the earliest site of activation was not successful and eventual successful ablation was at a distance of greater than 15 mm from the early activation site. We identified 3 patients (n = 3, 100% male) with evidence of reentrant arrhythmia based on slow conduction zones necessary for the tachycardia/arrhythmia, mid diastolic signals during VT or preceding bigeminal PVCs, pace mapping from the site abnormal signals reproducing the arrhythmia morphology but with prominent conduction delay, the entire cycle length of the tachycardia or coupling interval for the PVCs being mapping, or based on reset characteristics.ConclusionIn patients with atypical forms of RVOT VT, careful mapping and ablation of the myocardial sleeves near the pulmonic valve can eliminate the arrhythmia.

Epicardial Access and ObesityIntroductionPercutaneous epicardial access for ablative therapies is an increasingly common technique utilized for refractory ventricular arrhythmias. There are, however few known data on obesity and complication rates associated with this procedure.Methods and ResultsWe retrospectively reviewed the charts of subjects undergoing epicardial access at Mayo Clinic between January 2004 and June 2013. Baseline clinical and echocardiographic data were collected for each subject, who was then classified into body mass index (BMI) categories as underweight, normal weight, overweight, and obese based on a BMI of <18.5, 18.5–24.99, 25–29.99, and ≥30, respectively. Events and complications were recorded, and procedural and clinical success rates were determined.There was no statistically significant difference in access approach, procedural or clinical outcomes, or complications among the BMI categories. Note that 95.1%, 91.7%, and 93.1% derived procedural success among the normal weight, overweight, and obese categories, respectively (P value = 0.81). Similarly, there was no difference in clinical outcomes with success rates of 68.3%, 66.7%, and 75.9% between the respective groups (P value = 0.54). At 5 years, there was a trend toward increased mortality among obese individuals (28.8%) compared to normal weight (8.8%) and overweight (9.8%) patients (P value = 0.139).ConclusionPercutaneous epicardial access, mapping, and ablation can be performed in obese individuals with similar outcomes to those of lower weight category. Obesity should not preclude the use of percutaneous epicardial access when clinically indicated.

Renal Vein Stimulation Increases Blood PressureBackgroundNeurocardiogenic syncope (NCS) is a common and sometimes debilitating disorder, with no consistently effective treatment. NCS is due to a combination of bradycardia and vasodilation leading to syncope. Although pacemaker devices have been tried in treating the bradycardic aspect of NCS, no device‐based therapy exists to treat the coexistent vasodilation that occurs. The renal sympathetic innervation has been the target of denervation to treat hypertension. We hypothesized that stimulation of the renal sympathetic nerves can increase blood pressure and counteract vasodilation in NCS.Methods and ResultsHigh‐frequency stimulation (800–900 pps, 10 V, 30–200 seconds) was performed using a quadripolar catheter in the renal vein of 7 dogs and 1 baboon. A significant increase in blood pressure (BP; mean [SD] systolic BP 117 [±28] vs. 128 [±33], diastolic BP 75 [±19] vs. 87 [±29] mmHg) was noted during the stimulation, which returned to baseline after cessation of stimulation. The mean increase in systolic and diastolic BP was 13.0 (±3.3) (P = 0.006) and 10.2 (±4.6) (P = 0.08), respectively.ConclusionWe report the first ever study of feasibility and safety of high‐frequency electrical stimulation of the renal sympathetic innervation to increase BP in animal models. This has potential applications in the treatment of hypotensive states such as NCS.

Percutaneous Lead Revision for Cardiac PerforationIntroductionCardiac perforation is an infrequent but potentially life‐threatening complication associated with placement of a cardiac implantable electronic device (CIED). The objective of this study was to determine the outcomes of percutaneous lead revision in patients who had lead perforation of the myocardium after CIED placement.Methods and ResultsWe reviewed records of 1,458 patients who underwent CIED lead extraction or repositioning. Of these, 31 (2.1%) had the procedure performed for lead perforation as a complication of CIED placement. Demographic, clinical, and follow‐up characteristics of the patients were analyzed. Mean (SD) patient age was 65 (23) years. Cardiac perforation was detected within 24 hours after implantation in 9 patients, within 1 month in 17, and greater than 1 month in 5. Pericardiocentesis was performed with a pigtail drainage catheter in place before the lead revision in 17 patients (55%) who had pericardial effusion, with or without hemodynamic compromise. All culprit leads were successfully managed with percutaneous lead removal (n = 3 [10%]), new lead placement (n = 12 [38%]), or lead repositioning (n = 16 [52%]). Of the 17 patients with pericardiocentesis before the reoperation, none had tamponade develop; in contrast, 3 of the remaining 14 patients had tamponade develop and required urgent pericardiocentesis. All patients survived without requiring open chest surgery.ConclusionPercutaneous removal or repositioning of the perforating lead is feasible and appears effective. Placement of a prophylactic pericardial drain catheter may reduce the incidence of urgent pericardiocentesis during or after a procedure.

IntroductionAbandoned 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.MethodsThis 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.ResultsPatients (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.ConclusionThe 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.

Mitral Valve Injury with Catheter AblationIntroductionAn increasing number of catheter ablations involve the mitral annular region and valve apparatus, increasing the risk of catheter interaction with the mitral valve (MV) complex. We review our experience with catheter ablation‐related MV injury resulting in severe mitral regurgitation (MR) to delineate mechanisms of injury and outcomes.MethodsWe searched the Mayo Clinic MV surgical database over a 19‐year period (1993–2012) and the electrophysiologic procedures database over a 23‐year period (1990–2013) and identified 9 patients with catheter ablation related MV injury requiring clinical intervention.ResultsIndications for ablation included atrial fibrillation (AF) [n = 4], ventricular tachycardia (VT) [n = 3], and left‐sided accessory pathways [n = 2]. In all 4 AF patients, a circular mapping catheter entrapped in the MV apparatus was responsible for severe MR. In all 3 VT patients, radiofrequency energy delivery led to direct injury to the MV apparatus. In the 2 patients with accessory pathways, both mechanisms were involved (1 per patient). Six patients required surgical intervention (5 MV repair, 1 catheter removal). One patient developed severe functional MR upon successful endovascular catheter disentanglement that improved spontaneously. Two VT patients with persistent severe postablation MR were managed nonsurgically, 1 of whom died 3 months postprocedure.ConclusionCircular mapping catheter entrapment and ablation at the mitral annulus are the most common etiologies of MV injury during catheter ablation. Close surveillance of the MV is needed during such procedures and early surgical repair is important for successful salvage if significant injury occurs.