Martin R. Karch

Initial Experience with Intracardiac Atrial Defibrillation in Patients with Chronic Atrial Fibrillation

Atrial fibrillation is a common arrhythmia that was first recognized over 100 years ago. It can be found in up to 10% of those patients older than 65 years and represents a significant human health problem. It is by far the most common cardiac rhythm disorder associated with hospitalization.^ More than 1.5 million patients in the U.S. are affected by chronic atrial fibrillation. Beside the troublesome symptoms the patient might experience (awareness of the irregularity, sense of tachycardia, palpitations, fatigue, and diminished exercise tolerance], atrial fibrillation also adversely influences overall cardiac function in several different ways. The loss of atrial contraction impairs ventricular filling and the closure of the atrioventricular (AV) valves is affected, allowing mitral regurgitation. The increased heart rate itself may contribute to the development of congestive heart failure.^

Biatrial multisite mapping of atrial premature complexes triggering onset of atrial fibrillation.

Pulmonary veins are considered to be the most common origin of the focal activity that triggers the onset of atrial fibrillation (AF). However, little is known about the importance of ectopic activity located outside the pulmonary veins. This study included 45 patients (8 women and 37 men, mean age 55 +/- 12 years) with paroxysmal (n = 25) and persistent (n = 20) AF in whom multisite mapping of the right and left atria was performed using a 64-electrode basket catheter (n = 21) or a noncontact mapping system (n = 24). Spontaneous or orciprenaline-induced atrial premature complexes (APCs) were mapped. In all, 94 AF onsets from 38 distinct foci in 30 patients were observed and analyzed. Of these foci, 20 (53%) were located in pulmonary veins and 18 (47%) were located outside the pulmonary veins in other parts of the atria. In 22 patients (73%), AF was reproducibly induced by APCs from a single focus (59 episodes). In 8 patients (27%), AF originated from 2 distinct foci (35 episodes). Additionally, 20 of 30 patients (67%) who developed AF had APCs in different locations not inducing AF. APCs inducing AF had shorter coupling intervals than APCs not inducing AF (307 +/- 54 vs 409 +/- 76 ms, p <0.001). This study showed that 47% of ectopic foci triggering the onset of AF were located outside the pulmonary veins in extravenous parts of the left atrium and the right atrium, and 27% of patients had AF onsets of bifocal origin. These data challenge the current opinion that extrapulmonary foci play a minor role in inducing AF.

Clinical Experience With a Novel Multielectrode Basket Catheter in Right Atrial Tachycardias

BACKGROUND The complexity of atrial tachycardias (ATs) makes the electroanatomic characterization of the arrhythmogenic substrate difficult with conventional mapping techniques. The aim of our study was to evaluate possible advantages of a novel multielectrode basket catheter (MBC) in patients with AT. METHODS AND RESULTS In 31 patients with AT, an MBC composed of 64 electrodes was deployed in the right atrium (RA). The possibility of deployment, spatial relations between MBC and RA, MBC recording and pacing capabilities, mapping performance, and MBC-guided ablation were assessed. MBC deployment was possible in all 31 patients. The MBC was left in the RA for 175+/-44 minutes. Stable bipolar electrograms were recorded in 88+/-4% of electrodes. Pacing from bipoles was possible in 64+/-5% of electrode pairs. The earliest activity intervals, in relation to P-wave onset, measured from the MBC and standard roving catheters were 41+/-9 and 46+/-6 ms, respectively (P=0.21). Radiofrequency ablation was successful in 15 (94%) of 16 patients in whom it was attempted, including 2 patients with polymorphic right atrial tachycardia (RAT), 2 with RAT-atrial flutter combination, 1 with macroreentrant AT, and 1 with focal origin of atrial fibrillation. CONCLUSIONS These data demonstrate that MBC can be used safely in patients with right atrial arrhythmias. The simultaneous multielectrode mapping aids in the rapid identification of sites of origin of the AT and facilitates radiofrequency ablation procedures. The technique is especially effective for complex atrial arrhythmias.

Serial contrast-enhanced cardiac magnetic resonance imaging demonstrates regression of hyperenhancement within the coronary artery wall in patients after acute myocardial infarction.

OBJECTIVES Our aim was to determine whether serial contrast-enhanced cardiac magnetic resonance (CE-CMR) is useful for the characterization of tissue signal changes within the coronary vessel wall in patients after acute myocardial infarction (AMI). BACKGROUND Inflammation plays a key role in the development of AMI. CE-CMR of the vessel wall has been found useful for the characterization of inflammatory tissue signal changes in patients with carotid artery stenosis, giant cell arteritis, or Takayasus arteritis; however, it has never been serially performed in the coronary artery wall in patients with acute and chronic myocardial infarction using a gadolinium-based contrast medium and compared with systemic markers of inflammation. METHODS CE-CMR using a T1-weighted 3-dimensional gradient echo inversion recovery sequence of the coronary artery wall and 0.2 mmol/kg of gadolinium-diethylenetriaminepentaacetic acid was performed in 10 patients with AMI 6 days and 3 months after coronary intervention and in 9 subjects without coronary artery disease on invasive coronary angiography. Contrast-to-noise ratio (CNR) within the coronary artery wall was quantified in comparison with blood signal. RESULTS Patients with AMI demonstrated a significantly increased coronary vessel wall enhancement 6 days after infarction compared with normal subjects (CNR 7.8 +/- 4.4 vs. 5.3 +/- 3.2, p < 0.001). Three months after infarction, CNR decreased to 6.5 +/- 4.7 (p < 0.03). This decrease paralleled declines in C-reactive protein. Angiographically normal segments showed no contrast changes, but CNR significantly decreased in stenotic segments, from 10.9 +/- 3.8 to 6.8 +/- 5.0 (p < 0.002), resulting in a reduction of enhanced segments from 70% to 25% (p < 0.01). CONCLUSIONS Serial CE-CMR identified changes in spatial extent and intensity of coronary contrast enhancement in patients after AMI. This technique may be useful for the characterization of transient coronary tissue signal changes, which may represent edema or inflammation during the post-infarction phase. In addition, CE-CMR may offer the potential for visualization of inflammatory activity in atherosclerosis associated with acute coronary syndromes.

Acute and long-term results of radiofrequency ablation of common atrial flutter and the influence of the right atrial isthmus ablation on the occurrence of atrial fibrillation

Aims The purpose of this study was to evaluate the acute success rate and long-term efficacy of radiofrequency ablation of common type atrial flutter (AFL) by using a standardised anatomical approach in a large series of patients and to assess the influence of right atrial isthmus ablation on the occurrence of atrial fibrillation. There are no large scale prospective or retrospective multicentre studies for radiofrequency ablation of AFL. Methods and results The study population consisted of 363 consecutive patients with AFL (mean age 58±16 years, 265 men) who underwent radiofrequency ablation at the inferior vena cava-tricuspid annulus (IVC-TA) isthmus using a standardised anatomic approach. Bidirectional isthmus block at the IVC-TA was achieved in 328 patients (90%). Following radiofrequency ablation, 343 patients (95%) were followed for a mean of 496±335 days. During the follow-up period, 310 patients (90%) remained free of AFL recurrences. Multivariate analysis identified five independent predictors of AFL recurrence: fluoroscopy time \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p{<}0.001)\) \end{document}, atrial fibrillation after AFL ablation \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.01)\) \end{document}, lack of bidirectional block \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.02)\) \end{document}, reduced left ventricular function \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.035)\) \end{document} and right atrial dimensions \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \((p=0.046)\) \end{document}. Atrial fibrillation occurrence was significantly reduced after AFL ablation (112 in 343 patients, 33%) as compared to occurrence of atrial fibrillation before radiofrequency ablation (198 in 363 patients, 55%, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(p{<}0.001\) \end{document}). Conclusion The current anatomical ablation approach for AFL and criteria for evaluation of the IVC-TA isthmus block is associated with an acute success rate of 90% and a long-term recurrence rate of 10%. Radiofrequency ablation of common AFL results in a significant reduction in the occurrence of atrial fibrillation.

Acute and Long-Term Results of Slow Pathway Ablation in Patients with Atrioventricular Nodal Reentrant Tachycardia—An Analysis of the Predictive Factors for Arrhythmia Recurrence

Backqround: Predictors of atrioventricular nodal reentrant tachycardia (AVNRT) recurrence after radiofrequency ablation including the importance of residual slow pathway conduction are not known. The aim of this study was to report the acute and long‐term results of slow pathway ablation in a large series of consecutive patients with AVNRT and to analyze the potential predictors of arrhythmia recurrence with a particular emphasis on the residual slow pathway conduction after ablation.

Characterization of paroxysmal and persistent atrial fibrillation in the human left atrium during initiation and sustained episodes.

Characterization of AF in the LA. Introduction: Atrial fibrillation (AF) in the left atrium (LA) is poorly defined in terms of regional differences in the degree of organization, characteristics of paroxysmal and persistent variants, and electrophysiologic events that develop at the onset of episodes.

LocaLisa catheter navigation reduces fluoroscopy time and dosage in ablation of atrial flutter: a prospective randomized study.

Introduction: Catheter ablation has become a well‐established therapy for isthmus‐dependent right atrial flutter (AFL). Recently, mapping and ablation of AFL have been performed using sophisticated three‐dimensional mapping systems, such as electroanatomic and noncontact mapping systems. The LocaLisa system enables nonfluoroscopic navigation of intracardiac electrode catheters based on impedance changes related to catheter movements in transthoracic current fields. The aim of this randomized prospective study was to compare the efficacy of the LocaLisa system with the conventional mapping/ablation approach for radiofrequency ablation of AFL.

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium

OBJECTIVES The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA). BACKGROUND Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood. METHODS A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system. RESULTS Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71). CONCLUSIONS Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.

Noncontact Mapping‐Guided Catheter Ablation of Atrial Fibrillation Associated with Left Atrial Ectopy

Noncontact Mapping of Atrial Fibrillation. We report the use of a novel noncontact mapping system used to perform left atrial mapping and to guide radiofrequency ablation in two patients, each with atrial fibrillation (AF) triggered by left atrial ectopy. A noncontact multielectrode probe and ablation catheter were advanced into the left atrium through a transseptal puncture or a patent foramen ovale. Isopotential mapping delineated the focal origin at the ostium of the right lower pulmonary vein in one patient and close to the ostium of the left upper pulmonary vein in the other patient. The ablation catheter was guided to the target sites using a locator signal. The foci were ablated successfully in both patients. No recurrences of AF were observed during follow‐up at 4 and 6 months, respectively.