Weilun Quan

Development of an Interactive Computer‐Guided Method for Radiofrequency Catheter Ablation of Ventricular Tachycardia

The purpose of this study was to develop a simple computer‐guided approach to localizing ventricular tachycardias during ventricular mapping. Six patients with sustained monomorphic ventricular tachycardia were connected to a 32‐lead computer body surface mapping system. Isoarea maps of induced ventricular tachycardia were recorded. Then a pacing probe was placed in either the right or left ventricle, and maps were generated from a variety of sites. Differences between ventricular tachycardia and pace map maxima X,Y coordinates were utilized to guide catheter manipulation and localization. In 6 of 6 patients (100%) this method appeared to provide a systematic approach to ventricular tachycardia localization. Computer‐generated correlations as well as the X,Y coordinates of the QRS isoarea maxima were used to determine proximity to the ventricular tachycardia foci and direct catheter manipulation. In the next three patients this method was applied prospectively to help guide catheter manipulation during ventricular tachycardia (two right ventricular outflow tract tachycardias, and one left ventricular tachycardia). After a mean of 4.0 ± 1.7 radiofrequency applications, ventricular tachycardia was no longer inducible, and at 7 ± 0 months follow‐up there have been no arrhythmia recurrences. We conclude that online computerized body surface mapping can assist in localizing ventricular tachycardia. Differences in maxima during pace maps and in‐situ ventricular tachycardias can help with catheter manipulation as well as with more precise identification of focal tachycardias. This technique appears to hold the promise of a simple computer‐guided method that may facilitate radiofrequency catheter ablation.

Response of end-tidal CO/sub 2/ to atrial and ventricular paced tachycardias in a canine model: basis for an automatic physiologically responsive external defibrillator

The purpose of this study was to test the feasibility of end-tidal CO/sub 2/ (ETCO/sub 2/) as a parameter for incorporation into an automatic external defibrillator. Relative changes in ETCO/sub 2/ (/spl Delta/ETCO/sub 2/) were compared during atrial and ventricular paced tachycardias at cycle lengths of 350, 300, and 250 milliseconds in nine anesthetized dogs. Decreases in ETCO/sub 2/ during hemodynamically significant tachycardias were rapid and progressive with a return towards baseline immediately after tachycardia termination. For a given paced cycle length, decreases in ETCO/sub 2/, were significantly greater for ventricular pacing as compared to a trial pacing. We conclude that ETCO/sub 2/ appears to be a suitable parameter for incorporation into an automatic external defibrillator. Further research is necessary to determine the true clinical utility of such a system.

The "EP manager": a database management system for electrophysiology practice

A database program developed specifically for tracking all data collected during routine electrophysiology practice (EP) is described. The program is written in Filemaker Pro, a flat-file Macintosh based system. The database provides a standard of data entry and data integrity, easy retrieving and reporting clinical data. It assists in clinical decision making and improves the quality of care of patients as well as provides a historical data for future research and analysis.<<ETX>>

Evaluation of vasovagal syncope with body surface mapping during head-up tilt-table testing

Abstract In conclusion, during vasovagal syncope we observed an increase in the QRST isoarea gradient (reflecting greater uniformity of repolarization), possibly due to changes in autonomic tone. In contrast, we observed a decrease in the QRST isoarea gradient (increased disparity of repolarization) in patients without vasovagal syncope during HUT. Future research should examine the clinical use of BSM as an early predictor of vasovagal syncope before symptom onset during HUT, thus limiting patient discomfort.