Siva K. Mulpuru

Focal impulse and rotor modulation ablation of sustaining rotors abruptly terminates persistent atrial fibrillation to sinus rhythm with elimination on follow-up: A video case study

Ablation of atrial fibrillation (AF) by using strategies that eliminate AF triggers via pulmonary vein (PV) isolation1 produces a single procedure success of 45%-65% at up to 1 year.2 Importantly, while it is known that PV ectopy may trigger AF, the mechanisms that actually sustain human AF after it has been triggered are unclear. There are 2 prevailing hypotheses. The multiwavelet hypothesis is based on evidence that complex activation in AF represents continuously meandering electrical waves,3 while the localized source hypothesis is based on experimental models in which rapidly activating reentrant circuits (rotors)4 or focal impulses5 cause disorganized AF. There has until now been indirect6 but little7,8 or no3 direct evidence to support sustaining rotors in human AF. We present a gentleman referred because of persistent AF despite prior left atrial radiofrequency Maze and endocardial ablation procedures. In the electrophysiological study, novel computational mapping developed in our laboratory revealed one AF rotor in the right atrium and another in the left atrium. Brief 3-5-minute ablation applications at each rotor (focal impulse and rotor modulation [FIRM]) abruptly terminated AF to sinus rhythm, with non-inducibility on aggressive testing and no AF recurrence by continuous ECG monitoring over 6 months. A video recording of the entire case is provided as an online supplement.

Risk of stroke after catheter ablation versus cardioversion for atrial fibrillation: A propensity-matched study of 24,244 patients.

BACKGROUND Stroke is the major cause of morbidity and mortality related to atrial fibrillation (AF). Catheter ablation for AF is effective in reducing AF burden, but its impact on long-term stroke risk is unknown. OBJECTIVE We sought to evaluate the periprocedural and long-term stroke risk after catheter ablation or cardioversion for AF. METHODS This retrospective, propensity-matched study using a national administrative claims database identified patients with AF who underwent catheter ablation and a comparison group (matched on age, sex, year of treatment, CHA2DS2-Vasc score, and Charlson index) who underwent cardioversion between 2005 and 2012. The primary end points were (1) time to first ischemic or hemorrhagic stroke or transient ischemic attack (TIA) and (2) time to first ischemic or hemorrhagic stroke excluding TIA. We compared periprocedural incident stroke (within 30 days of ablation or cardioversion) as well as total strokes between the 2 groups. RESULTS A total of 24,244 patients (12,122 patients undergoing ablation and 12,122 patients undergoing cardioversion) were included in the analysis. Incident periprocedural stroke or TIA occurred in 0.5% of the ablation group and 0.3% of the cardioversion group (P = .04). There was a significant initial risk of stroke/TIA with ablation within the first 30 days (rate ratio 1.53; P = .05). After 30 days, this risk was significantly lower in the ablation group (rate ratio 0.78; P = .03). CONCLUSION In patients with AF, there is a small periprocedural stroke risk with ablation in comparison to cardioversion. However, over longer-term follow-up, ablation is associated with a slightly lower rate of stroke.

Atypical complications encountered with epicardial electrophysiological procedures

BACKGROUND With the increasing use, complexity, anatomical approaches, and tools related to epicardial procedures, complications previously not seen during endovascular ablation are now well recognized with epicardial ablation. Whether newer approaches and the regional anatomy of the pericardial space contribute to unexpected complications after epicardial access (EpiAcc) is presently unknown. OBJECTIVE To characterize underreported, or novel, complications associated with percutaneous EpiAcc as part of an electrophysiology procedure. METHODS We retrospectively reviewed percutaneous EpiAcc as part of an ablation procedure from January 1, 2004, to December 31, 2011. RESULTS Of 116 attempts in 107 patients, 8 atypical ablation complications (no procedural deaths) were noted; complications included delayed pericarditis (2 weeks), chronic refractory pericarditis, requirement for snaring of broken intrapericardial wire, pleural perforation, phrenic nerve injury despite protective strategies, hemoperitoneum, and abdominal-pericardial fistula. CONCLUSION Vigilance both during and after EpiAcc is needed to recognize these complications, some of which may be life-threatening.

Trends in Use and Adverse Outcomes Associated with Transvenous Lead Removal in the United States

Background— Transvenous lead removal (TLR) has made significant progress with respect to innovation, efficacy, and safety. However, limited data exist regarding trends in use and adverse outcomes outside the centers of considerable experience for TLR. The aim of our study was to examine use patterns, frequency of adverse events, and influence of hospital volume on complications. Methods and Results— Using the Nationwide Inpatient Sample, we identified 91 890 TLR procedures. We investigated common complications including pericardial complications (hemopericardium, cardiac tamponade, or pericardiocentesis), pneumothorax, stroke, vascular complications (consisting of hemorrhage/hematoma, incidents requiring surgical repair, and accidental arterial puncture), and in-hospital deaths described with TLR, defining them by the validated International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code. We specifically assessed in-hospital death (2.2%), hemorrhage requiring transfusion (2.6%), vascular complications (2.0%), pericardial complications (1.4%), open heart surgery (0.2%), and postoperative respiratory failure (2.4%). Independent predictors of complications were female sex and device infections. Hospital volume was not independently associated with higher complications. There was a significant rise in overall complication rates over the study period. Conclusions— The overall complication rate in patients undergoing TLR was higher than previously reported. Female sex and device infections are associated with higher complications. Hospital volume was not associated with higher complication rates. The number of adverse events in the literature likely underestimates the actual number of complications associated with TLR.

Mechanism and outcomes of catheter ablation for ventricular tachycardia in adults with repaired congenital heart disease

BACKGROUND Repaired congenital heart disease (rCHD) is strongly associated with ventricular tachycardia (VT) as an important late cause of morbidity and mortality. Ventricular reentry most commonly includes anatomic isthmuses created during the repair procedures. OBJECTIVE The purpose of this study was to analyze the long-term outcomes of catheter ablation, a commonly used standalone or adjunctive therapy, in a cohort of rCHD patients. METHODS A retrospective analysis of 21 consecutive patients with rCHD (45.0 ± 3.0 years, 71.4% male) undergoing ablation for VT was performed. The primary composite outcome was defined as in-hospital arrhythmic death, out-of-hospital sudden cardiac death, or appropriate implantable cardioverter-defibrillator therapy. RESULTS At initial electrophysiologic study, 14 patients (66.7%) had reentrant VT through an electroanatomic isthmus; the remaining 7 patients (33.3%) demonstrated focal VT. Isthmus-dependent reentry was identified as the mechanism for VT in 14 patients (66.7%), and conduction block was confirmed in 8 of these patients (57.1%). No patients with confirmed block developed VT recurrence. During long-term follow-up (33 ± 7 months), 20 of 21 patients (95.2%) had not reached the primary composite outcome. Three patients died of nonarrhythmic causes. CONCLUSION Catheter-based VT ablation in patients with rCHD is associated with a low rate of VT recurrence. Focal VT was not uncommon in this cohort. If a reentrant mechanism is present, confirmation of conduction block across the isthmus is vital to prevent recurrence.

Utility and safety of temporary pacing using active fixation leads and externalized re-usable permanent pacemakers after lead extraction

AIMS After extraction of an infected cardiac implantable electronic device (CIED) in a pacemaker-dependent patient, a temporary pacemaker wire may be required for long periods during antibiotic treatment. Loss of capture and under sensing are commonly observed over time with temporary pacemaker wires, and patient mobility is restricted. The use of an externalized permanent active-fixation pacemaker lead connected to a permanent pacemaker generator for temporary pacing may be beneficial because of improved lead stability, and greater patient mobility and comfort. The aim of this study was to investigate the efficacy and safety of a temporary permanent pacemaker (TPPM) system in patients undergoing transvenous lead extraction due to CIED infection. METHODS AND RESULTS Of 47 patients who underwent lead extraction due to CIED infection over a 2-year period at our centre, 23 were pacemaker dependent and underwent TPPM implantation. A permanent pacemaker lead was implanted in the right ventricle via the internal jugular vein and connected to a TPPM generator, which was secured externally at the base of the neck. The TPPM was used for a mean of 19.4 ± 11.9 days (median 18 days, range 3-45 days), without loss of capture or sensing failure in any patient. Twelve of 23 patients were discharged home or to a nursing facility with the TPPM until completion of antibiotic treatment and re-implantation of a new permanent pacemaker. CONCLUSION External TPPMs are safe and effective in patients requiring long-term pacing after infected CIED removal.

Device Infections Management and Indications for Lead Extraction

An 83-year-old woman is referred for lead extraction as a result of pacemaker pocket infection. She has a history of atrial fibrillation and complete heart block after an AV node ablation. A left-sided pacemaker was placed in 2007. One month before admission, she developed urosepsis, followed by an infection of the pacemaker pocket. Blood cultures revealed methicillin-sensitive Staphylococcus aureus . She was admitted to an outside institution where the device was removed, but the leads were left in place after a failed attempt to remove the leads with traction alone. A new single-chamber pacemaker was placed on the right side. On presentation to our institution, the patient appeared quite ill. Physical examination documented congestive heart failure and evidence of pocket infection at sites on both the right and left sides of the chest. Serum chemistry was significant for worsening renal function. A chest x-ray demonstrated a large right pleural effusion. The patient was taken to the hybrid operating room for further management. A transesophageal echocardiogram performed under general anesthesia showed a large pericardial effusion compromising ventricular filling, and a pericardial drain was placed. A temporary pacing wire was placed in the right ventricular apex via a femoral approach. The recently implanted right-sided pacemaker system could then be removed with traction under fluoroscopic guidance. The 2 left-sided leads were extracted with locking stylets and a laser sheath. Both wounds were extensively debrided, and bilateral wound vacuums were placed. An active fixation pacemaker lead was then placed via a right internal jugular approach and connected to a previously used, resterilized pacemaker to provide temporary/permanent right ventricular pacing. Finally, a right-sided chest tube was placed. The patient remained hospitalized for 2 weeks for management of her infected pacemaker sites and sepsis, with her initial care in the intensive care unit and with collaboration …

Sites of Successful Ventricular Fibrillation Ablation in Bileaflet Mitral Valve Prolapse Syndrome

Background—Although the vast majority of mitral valve prolapse (MVP) is benign, a small subset of patients, predominantly women, with bileaflet prolapse, complex ventricular ectopy (VE), and abnormal T waves comprise the recently described bileaflet MVP syndrome. We compared findings on electrophysiological study in bileaflet MVP syndrome patients with and without cardiac arrest to identify factors that may predispose to malignant ventricular arrhythmia. Methods and Results—Fourteen consecutive bileaflet MVP syndrome patients (n=13 women; median [limits], age at index ablation, 33.8 [21.0–58.7] years; ejection fraction, 60% [45%–67%]; all ⩽ moderate mitral regurgitation; n=6 with previous cardiac arrest and implantable cardioverter defibrillator shocks for ventricular fibrillation; and n=8 without implantable cardioverter defibrillator although with symptomatic complex VE) were included. The 2 groups had similar baseline echocardiographic and electrocardiographic characteristics. All patients had at least 1 left ventricular papillary or fascicular VE focus. Purkinje origin VE was identified as the ventricular fibrillation trigger in 6 of 6 cardiac arrest patients (4 from papillary muscle) and Purkinje origin of dominant VE was seen in 5 of 8 (3 from papillary muscle) nonarrest patients. Acute success was seen in 17 of 19 procedures, and a ventricular fibrillation storm occurred within 24 hours of ablation in a single patient. Repeat ablation for recurrent symptomatic arrhythmia was performed in 6 patients. At 478 (39–2099) days of follow-up, 2 cardiac arrest patients received appropriate shocks. Symptoms from VE were reduced in 12 of 14. Conclusions—Bileaflet MVP syndrome is characterized by fascicular and papillary muscle VE that triggers ventricular fibrillation. Ablation of clinically dominant VE foci improves symptoms and reduces appropriate implantable cardioverter defibrillator shocks.

Synchronous ventricular pacing with direct capture of the atrioventricular conduction system: Functional anatomy, terminology, and challenges

Right ventricular apical pacing is associated with an increased incidence of heart failure, atrial fibrillation, and overall mortality. As a result, pacing the ventricles in a manner that closely mimics normal AV conduction with an intact His-Purkinje system has been explored. Recently, the sustainable benefits of selective His-bundle stimulation have been demonstrated and proposed as the preferred method of ventricular stimulation for appropriate patients. Ideally, conduction system pacing should be selective without myocardial capture, overcome distal bundle branch block when present, and not compromise tricuspid valve function. Contemporary literature on conduction system pacing is confusing largely because of inconsistent terminology and, at times, anatomically inaccurate terms used interchangeably for nonsynonymous anatomic sites. In this review, we discuss the functional anatomy of AV conduction access with specific emphasis on terminology, relationship to the membranous septum, tricuspid valve tissue, and proximity to atrial or ventricular myocardium. The potential benefits of each specific site as well as associated unique difficulties with those sites are described.

Electrophysiologic Characteristics of Ventricular Arrhythmias Arising From the Aortic Mitral Continuity - Potential Role of the Conduction System

Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown.