David Krum

Computed Tomography‐Fluoroscopy Image Integration‐Guided Catheter Ablation of Atrial Fibrillation

Introduction: This study examines the feasibility of atrial fibrillation (AF) ablation using registered three‐dimensional computed tomography (CT) images of the left atrium with fluoroscopy.

Registration of 3D computed tomographic images with interventional systems: Implications for catheter ablation of atrial fibrillation

Despite the great promise catheter ablation offers in the treatment of complex arrhythmias such as atrial fibrillation (AF), long procedure times and somewhat suboptimal results hinder the widespread use of this technique. As fluoroscopy does not provide contrast differentiation between the area of interest and the surrounding structures, there is a lack of proper intra procedure image guidance. Segmentation of anatomical structures such as the left atrium (LA) can be performed using images obtained with modalities such as computed tomography (CT). However, unlike the cardiac mapping systems, these imaging systems do not track catheters in real time. This review addresses the evolving concept of image registration to deliver therapy in cardiac arrhythmias.

Catheter location, tracking, cardiac chamber geometry creation, and ablation using cutaneous patches.

Objective: The ability to construct a three-dimensional (3-D) surface model of the endocardium and track the location of catheters within a cardiac chamber, using only cutaneous patches, would be a useful advancement in treating arrhythmias. We tested the feasibility of such a system, Ensite NavX (Endocardial Solutions, Inc., St. Paul, MN, USA), in patients undergoing catheter ablation for SVTs.Methods: Sixteen patients with 20 arrhythmias undergoing ablation were selected. Skin electrode patches were placed on the chest to create a 3-D coordinate system. A low-amplitude, 5.7 kHz signal emitted from the patches was received by conventional catheters positioned in the heart.Catheter location was determined by measuring the field strength received by the catheters. Location points were successively acquired while catheters were moved throughout the chamber. This information was collected and processed by a workstation to create a detailed 3-D model of the endocardial surface. Anatomic landmarks were labeled on the model as the mapping catheter was navigated. 3-D cardiac chamber geometry reconstruction, landmark labeling, and real time catheter tracking were performed successfully in all patients. Up to six catheters, with a total of up to 26 intracardiac electrodes, were tracked simultaneously.Results: Constructed geometries, including major vessels and valves, correlated closely with traditional anatomic models as well as intracardiac recordings and fluoroscopic images.Conclusions: Real-time catheter tracking and 3-D cardiac chamber model construction is feasible using cutaneous patches and conventional catheters. This approach may be useful in the treatment of patients with cardiac arrhythmias where ablation therapy is primarily anatomically based.

Pulmonary vein isolation and linear lesions in atrial fibrillation ablation

BackgroundVarious strategies have been used for atrial fibrillation (AF) ablation. It is unclear whether adding linear lesions to pulmonary vein (PV) isolation has significant advantages.ObjectivesWe assessed the clinical benefit of adding linear lesions in patients undergoing PV isolation for AF.MethodsOne hundred patients (63 male and 37 female; mean age of 59u2009±u200911xa0years) with documented paroxysmal AF were included in the study. Patients were randomized into two groups. The first group underwent PV isolation alone. The second group underwent PV isolation and had two linear lesions created; one line between the superior PVs, and a second line from the left inferior PV to the mitral valve annulus. Patients’ clinical progress after the ablation was evaluated and compared at 1, 3, and 9xa0months after their respective ablation procedures.ResultsThe linear lesions group maintained sinus rhythm and had fewer symptoms than the lone PV isolation group (86 vs. 58%, respectively) (pu2009<u20090.05) at 1xa0month. At 9xa0months, when patients who reverted to AF underwent additional management to regain sinus rhythm (90 vs. 82%, respectively) (pu2009=u2009NS), there was no statistical difference between the groups regarding the use of antiarrhythmics, the need for electrical cardioversion, and subjective improvement.ConclusionThe addition of linear lesions to PV isolation more effectively achieved sinus rhythm initially and fewer patients required additional management to maintain their rhythm when compared to patients who underwent lone PV isolation. However, at 9xa0months, the overall results were similar in both groups.

Noncontact Mapping for Radiofrequency Ablation of Complex Cardiac Arrhythmias

Radiofrequency (RF) catheter ablation is the current treatment of choice for several cardiac arrhythmias. The conventional approach utilizing intracardiac electrograms during sinus rhythm and during tachycardia has inherent limitations, including limited two-dimensional fluoroscopic imaging and limited ability to evaluate several potential sites for ablation then go precisely to the most suitable site. Recently, a noncontact mapping system has been developed that can be used to perform single beat high resolution mapping of cardiac arrhythmias. In this report, we describe the advantage of utilizing the system in facilitating a successful outcome in 5 patients with different complex arrhythmias.

Posterior left atrial–esophageal relationship throughout the cardiac cycle

BackgroundRadiofrequency energy delivered throughout the cardiac cycle has the potential to cause thermal injury to the esophagus if the anatomical relationship between the posterior left atrium and the esophagus changes during cardiac motion.ObjectiveTo assess the posterior left atrial–esophageal relationship throughout the cardiac cycle.MethodsIn this study, the anatomical relationship between the posterior left atrium and the esophagus was assessed throughout the cardiac cycle in 10 consecutive patients. All patients underwent contrast-enhanced, ECG-gated CT scanning. Left atrial volumes and the esophageal structure were generated from the reconstructed data at 10 phases of the cardiac cycle from 5% to 95% of the R–R interval. The posterior left atrial–esophageal anatomical relationship was measured at four levels, the superior pulmonary vein ostial site, and the upper, mid and lower left atrium.ResultsThere were significant variations in the left atrial–esophageal relationship in the 10 patients. The relative movement between the esophagus and the posterior left atrium throughout the cardiac cycle in the anteroposterior and right-to-left orientations was 0.55u2009±u20090.99xa0mm and 0.60u2009±u20091.02xa0mm (95% confidence interval, 2.03 and 1.98 respectively).ConclusionsUnder normal conditions, there is little change in the anatomical relationship between the posterior left atrium and the esophagus during the entire cardiac cycle. However, due to the interpatient variability at the esophageal location, identification of esophageal location may help prevent complications during catheter ablation procedures involving the left atrium.

Correlation of spontaneous and induced premature atrial complexes initiating atrial fibrillation in humans: electrophysiologic parameters for guiding therapy.

Atrial Fibrillation Induction and Ablation. Introduction: The low frequency of spontaneous premature atrial contractions (PACs) may be an impediment to mapping and ablation of atrial fibrillation (AF). It has been shown that PACs following external or internal cardioversion of AF can initiate AF. If this method could reproducibly induce PACs from the same location as spontaneous PACs, it would be clinically significant. High‐resolution noncontact mapping can map a single beat, should help identify the sites of spontaneously occurring PACs and PACs induced following cardioversion of spontaneous or induced AF, and could help correlate the trigger sites for AF induction.

Safety of Atrial Defibrillation Shocks Synchronized to Narrow and Wide QRS Complexes During Atrial Pacing Protocols Simulating Atrial Fibrillation in Dogs

BACKGROUNDnThe potential ventricular proarrhythmic effect of atrial defibrillation shocks (ADS) remains a concern with automatic internal atrial defibrillation. Optimal R-wave synchronization alone may not be sufficient to prevent the induction of ventricular fibrillation (VF).nnnMETHODS AND RESULTSnThe proarrhythmic effect of ADS synchronized to normally conducted QRS complexes (NQRS) and to supraventricular complexes with left or right bundle-branch block (L/RBBB) was investigated in a canine atrial pacing study. Short-long-short, single premature, and burst pacing protocols from the high right atrium were performed at baseline, during isoproterenol infusion, and after intravenous procainamide. The ADS were delivered between decapolar catheters in the coronary sinus and lateral right atrium. They were initially delivered 20 milliseconds (ms) after the end of the last conducted QRS complex and then scanned decrementally through that complex until VF was induced. For NQRS complexes, VF occurred only when the ADS were delivered at or before the onset of the QRS complex and never during the complex itself. In the presence of LBBB or RBBB, VF was induced by ADS delivered at the onset of or within the first 45 ms of the QRS complex in 16 animals. The longest RR (VV) intervals preceding ADS-induced VF were 345 ms at baseline and 380 ms after procainamide.nnnCONCLUSIONSnIn this study, ADS synchronized to NQRS complexes appeared to be safe regardless of the preceding RR interval. In the presence of LBBB or RBBB, RR intervals preceding the ADS of >345 ms at baseline and >380 ms in the presence of procainamide would have been required to avoid VF. Alternatively, ADS delivered 50 ms after the onset of the RV electrogram appeared to be safe in all circumstances regardless of the preceding RR interval.

Common ostium of the inferior pulmonary veins in a patient undergoing left atrial ablation for atrial fibrillation.

CT scanning prior to left atrial ablation can serve as a useful road map for patients undergoing these procedures, especially given the complex and highly variable anatomy of the pulmonary veins. This patient, a 56-year-old male with paroxysmal atrial fibrillation, underwent contrast-enhanced CT scanning (Lightspeed VCT, GE Healthcare, Waukesha, WI, USA) using ECG-gated acquisition. The images, taken at 75% of the R—R interval, were processed on a workstation (Advantage Windows with CardEP software, GE Healthcare, Waukesha, WI, USA) to produce the three-dimensional volumes shown here. Panel A is a posteroanterior view of the segmented left atrium, and Panel B shows an endocardial view in the anteroposterior orientation with the front part of the left atrium cut away. This reveals the posterior wall of the left atrium. The images reveal an unusual anatomic subtype for pulmonary vein anatomy. The left and right upper pulmonary veins (LSPV, RSPV) branch off from the left atrium in typical fashion; however, the two inferior pulmonary veins (LIPV, RIPV) converge near the midline of the posterior left atrium, forming a large common ostium (Common Os). The inferior veins were isolated at the common ostium using a basket catheter (Boston Scientific/EP Technologies, Natick, MA, USA). The procedure was completed without any adverse events. This unique anatomical variation has not yet, to our knowledge, been described in the literature. It underscores the importance of CT scanning in pre procedure planning for AF ablation. J Interv Card Electrophysiol (2006) 15:203 DOI 10.1007/s10840-006-9013-9

Endocardial noncontact activation mapping of idiopathic left ventricular tachycardia.

Mapping of Idiopathic Ventricular Tachycardia. Idiopathic left ventricular tachycardia with a right bundle, left‐axis deviation is thought to originate from posterior fascicles. Recently, there has been considerable interest in the anatomic and mechanistic basis of this arrhythmia. We report our experience with a 26‐year‐old man in whom new noncontact mapping technology was used to acquire detailed data from the left ventricle, identify the mid‐diastolic potential and part of the ventricular tachycardia circuit, and perform successful ablation. This information helped define the physiologic aspects of this unique tachycardia.