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Biomedical subjects

Jasbir Sra

Publications and source records attributed to Jasbir Sra.

17 recordsLinked to original sources
PubMed2005

Atrial tachycardia arising from the coronary sinus musculature: electrophysiological characteristics and long-term outcomes of radiofrequency ablation.

OBJECTIVES: We sought to describe the electrophysiological features and long-term outcome after radiofrequency catheter ablation (RFCA) of atrial tachycardia (AT) arising from the coronary sinus (CS) musculature. BACKGROUND: Atrial tachycardia requiring RFCA deep within the CS has been described in isolated case reports. However, the mechanism and exact site of origin of this tachycardia have not been well elucidated. METHODS: The study included 8 patients (5 men) of a consecutive series of 283 patients undergoing RFCA for focal AT. RESULTS: In sinus rhythm, a discrete potential (P) was noted after the CS atrial electrogram and during tachycardia, the CS (P) preceded the surface P-wave by 30 to 50 ms. The CS (P) always preceded the earliest electrogram in the left atrium (LA). Three-dimensional electroanatomical mapping was available in four patients, and in one case it showed earliest activation in the CS with rapid spread to the proximal CS and then to the LA. Ablation of the AT initially attempted from the earliest site in the LA in three patients was unsuccessful. In all patients the tachycardia was safely and successfully ablated at a site 3.6 cm within the CS. There has been no recurrence over a follow-up of 37 +/- 13 months. CONCLUSIONS: Focal AT emanating deep within the CS musculature can be recognized by a discrete potential associated with the CS atrial signal both during sinus rhythm and tachycardia. Long-term success without complications can be accomplished by ablating within the CS in close proximity to the CS (P).

Adolescent↗
PubMed2005

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.

Adult↗
PubMed2005

Feasibility and validation of registration of three-dimensional left atrial models derived from computed tomography with a noncontact cardiac mapping system.

OBJECTIVES: The purpose of this study was to determine the feasibility and assess the validity of registering three-dimensional (3D) models from computed tomographic (CT) images using a cardiac mapping system. BACKGROUND: Registration of 3D anatomic models with an interventional system could help identify and navigate mapping and ablation catheters over a complex structure such as the left atrium (LA). METHODS: ECG-gated, contrast-enhanced cardiac CT imaging was performed in 14 patients with atrial fibrillation. Segmentation was used to create 3D models of the LA. The 3D models were registered with the mapping system using a series of fiducial points. Registration was accomplished retrospectively in the first 10 patients, and catheter navigation was visualized from recorded data. In the final four patients, registration was accomplished in real time during electrophysiologic study. The mapping catheter position, as it was navigated inside the LA, was applied to the registered model in real time. For the validation study, temporary pacing leads were implanted in the LA of 10 dogs. Following this, CT scanning, segmentation, LA model importation, and registration was described previously. After registration, a mapping catheter was positioned at the site of each buried lead according to the registered model with no fluoroscopic guidance. A radiofrequency lesion was created at this location, and the dog was sacrificed, the heart removed and stained, and the distance between the buried lead and the lesion measured. RESULTS: During the feasibility study, the location of the catheter in the registered model correlated with fluoroscopy, angiography, and intracardiac electrograms. LA endocardial potentials during sinus rhythm and any premature atrial contractions also were successfully delineated over the registered models. In the validation study, the mean target registration error was 2.0 +/- 3.6 mm. CONCLUSIONS: Registration of CT-derived 3D models of the LA using a cardiac mapping system is feasible and accurate.

Animals↗
PubMed2004

The implantable cardioverter defibrillator: technology, indications, and impact on cardiovascular survival.

Since the introduction of the implantable cardioverter defibrillator (ICD) for the management of patients with high risk of arrhythmic SCD, there has been increasing use of this device. Its basic promise to effectively terminate ventricular tachycardia (VT)-ventricular fibrillation (VF) has been repeatedly met. In several randomized trials, the ICD has been shown to be superior to conventional anti-arrhythmic therapy, both in patients with documented VT-VF (secondary prevention) and those with high risk such as left ventricular ejection fraction and no prior sustained VT-VF (primary prevention). In both groups, the ICD showed overall and cardiac mortality reduction. The device now can more accurately detect VT-VF and differentiate these from other arrhythmias through a series of algorithms and direct-chamber sensing. Therapy options include painless antitachycardia pacing, low-energy cardioversion, and high-energy defibrillation. The technique implant is now simple as a pacemaker with one lead attached to an active (hot) can functioning as the other electrode. Among other improvements is its weight, volume, multiprogrammability, and storage of information,dual-chamber pacing and sensing, dual-chamber defibrillation, and addition of biventricular pacing for cardiac synchronization. It is anticipated that further improvement in ICD technology will take place and the list of indications will grow.

Algorithms↗
PubMed2004

Noncontact and electroanatomic mapping of atrial flutter in surgically repaired sinus venosus atrial septal defect and rerouting of anomalous pulmonary venous drainage.

Atypical atrial flutter with two prior failed ablations, complicating surgically repaired sinus venosus atrial septal defect and partial anomalous pulmonary venous connection, mapped by noncontact and electroanatomic mapping, is described. Electroanatomic and noncontact mapping clearly identified a narrow zone of normal voltage and activation which was targeted, with successful termination of the arrhythmia.

Adult↗
PubMed2002

Validation of a left atrial lesion pattern for intraoperative ablation of atrial fibrillation.

BACKGROUND: Evidence that atrial fibrillation may begin in early stages from triggers or reentry circuits primarily in the left atrium suggests that the entire Maze 3 lesion pattern may be unnecessary. In the present study we describe a new left atrial lesion pattern for intraoperative linear ablation of chronic atrial fibrillation. METHODS: Endocardial radiofrequency ablation was performed on 12 dogs with chronic atrial fibrillation. Lesions to isolate pulmonary veins in pairs, the left atrial appendage, and connecting lesions between these structures were administered in a randomized approach. RESULTS: Twelve dogs were in chronic atrial fibrillation for 31 +/- 21 days before ablation. Atrial fibrillation was successfully ablated and rendered noninducible in all 12 dogs. All treatment failures observed with less than the full lesion pattern became a success when the remaining lesions were given. CONCLUSIONS: Atrial fibrillation ablation using this left atrial lesion pattern is highly successful in this model. This approach may have significant utility as a concomitant procedure for patients with atrial fibrillation undergoing mitral valve procedures.

Animals↗
PubMed2002

Radiofrequency ablation of atrial fibrillation during mitral valve surgery.

Twenty-three patients underwent endocardial radiofrequency ablation of atrial fibrillation (AF) during mitral valve procedures with a previously described left atrial lesion pattern. A temperature-controlled 7-coil surgical probe delivered 60-second lesions at 80 degrees C. The left atrial appendage was oversewn after ablation. Ages ranged from 28 to 88 years. Nineteen patients had chronic AF that was present for over 1 year in 74%; 12 patients had rheumatic mitral stenosis. Mean left atrial diameter was 5.4 +/- 0.7 cm. There was 1 operative death unrelated to the ablation, and no strokes or ablation-related complications were observed. At mean follow-up of 32.5 weeks, 86% of the 22 survivors were in sinus rhythm. All 18 patients with left atrial diameter <6 cm are in sinus rhythm. All postoperative atrial flutter was transient, and no patients required subsequent transcatheter ablation. This lesion pattern is safe and effective when applied in the method described here. It appears to be a reasonable alternative to the complete Maze 3 lesion pattern in patients with mitral valve disease.

Adult↗