Melissa L. McKernan

University of Pennsylvania, Philadelphia, PA, United States

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Publications (5)15.23 Total impact

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    ABSTRACT: Pulmonary vein electrical isolation (PVI) is an effective treatment for atrial fibrillation (AF). However, recurrence of pulmonary vein (PV) conduction after ablation may limit long-term success. We sought to determine the clinical predictors of acute PV reconnection during PVI and assess the long-term clinical outcomes associated with this phenomenon. We studied all patients with AF referred for PVI between November 2000 and August 2004. Over the course of the study period, PVI of arrhythmogenic PVs was performed segmentally using a 4-mm tip (52 degrees , 40 W, up to 90 seconds) or 8-mm tip catheter (50 degrees , 70 W, up to 60 seconds). PVI was defined as entry and exit block using a multipolar Lasso catheter. All veins were resampled to confirm isolation after 20-60 minutes. AF control was defined as no AF on or off a previously ineffective antiarrhythmic drug. Follow-up data included transtelephonic monitoring and clinical data collection from patient interviews. There were 424 patients who underwent isolation of 1,347 PVs during the study period. Acute reconnection of at least one PV occurred in 211 (50%) of the 424 patients and 326 (24%) of 1,347 of the PVs targeted. The left superior PV was most likely to acutely recover conduction compared with the other veins (left superior 31%, right superior 26%, right inferior 22%, left inferior 24%; P = .03). Patients with acute reconnection were more likely to be older, have a larger left atrium, have a history of hypertension or obstructive sleep apnea, and demonstrate persistent AF. After a single procedure, AF control was achieved in 153 (70%) of the 213 patients who demonstrated acute PV reconnection compared with 148 (73%) of 211 patients without acute PV reconnection observed (P = .52). Acute return of PV conduction is common after successful PVI and is more likely to occur in older patients with nonparoxysmal AF, hypertension, a large left atrium, and sleep apnea. There was no significant difference in acute PV reconnection between the 4-mm and 8-mm tip RF catheter despite differences in power and duration of energy delivery. Furthermore, there was no effect of PV reconnection on long-term AF control after repeated disconnection was performed.
    Full-text · Article · Oct 2006 · Heart Rhythm
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    ABSTRACT: Atrial fibrillation (AF) ablation procedures typically involve isolation of all pulmonary veins (PVs) in addition to adjunctive linear lesions, yet the need for such an extensive ablation strategy in all patients is unclear. The purpose of this study was to identify a subgroup of patients undergoing AF ablation with good clinical success after limited PV isolation. Patients (N = 450) underwent trigger-guided segmental isolation of only arrhythmogenic PVs. We compared clinical characteristics of patients who required isolation of only one or two PVs to those in whom AF ablation required isolating > or = 3 PVs. For the group of patients undergoing isolation of < or = 2 PVs, AF freedom without antiarrhythmic drug use was achieved in 56 (58%) of 97 patients, and AF control was achieved in 66 (68%) of 97 patients after a single procedure. After additional procedures, 77 (79%) of 97 patients achieved complete AF freedom without antiarrhythmic drugs, and 82 (85%) of 97 patients achieved AF control. Younger age (odds ratio [OR] 1.05; confidence interval [CI] 1.01,1.09) and lack of persistent AF (OR 3.27; CI 1.0, 10.7) were each independent predictors of freedom from AF. In patients younger than 50 years with paroxysmal AF undergoing isolation of < or = 2 PVs (n = 44), AF freedom without antiarrhythmic drugs was achieved in 32 (73%) of 44 after a single ablation procedure. Targeted PV isolation has a good long-term (18-month) success rate in patients younger than 50 years with paroxysmal AF and < or = 2 PVs triggering AF.
    No preview · Article · Feb 2006 · Heart Rhythm

  • No preview · Article · May 2005

  • No preview · Article · May 2005 · Heart Rhythm
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    ABSTRACT: Repetitive monomorphic VT occurring in the absence of structural heart disease typically originates in the outflow tract regions of the right and less commonly the left ventricles [1–8]. An unusual origin for this tachycardia in the outflow tract region is the cusps of the aortic valve. Importantly, this site of origin may be more common than previously recognized [9, 10]. This review will 1) characterize the anatomic relationship of the pulmonic and aortic valves, 2) identify surface electrocardiographic clues that suggest an origin from the aortic cusps and 3) describe the use of magnetic electroanatomic recording and intracardiac echo for identifying precise catheter position when mapping and ablating in the aortic cusp region and finally 4) describe an ablation and energy delivery strategy at these sites which are in close proximity to the ostium of the coronary arteries.
    No preview · Chapter · Jan 2004