Publications by authors named "Austin Davies"

5 Publications

  • Page 1 of 1

Open surgical ablation of ventricular tachycardia: Utility and feasibility of contemporary mapping and ablation tools.

Heart Rhythm O2 2021 Jun 11;2(3):271-279. Epub 2021 May 11.

University of Colorado School of Medicine, Division of Cardiology, Section of Cardiac Electrophysiologist, Aurora, Colorado.

Background: Ventricular tachycardia (VT) catheter ablation success may be limited when transcutaneous epicardial access is contraindicated. Surgical ablation (SurgAbl) is an option, but ablation guidance is limited without simultaneously acquired electrophysiological data.

Objective: We describe our SurgAbl experience utilizing contemporary electroanatomic mapping (EAM) among patients with refractory VT storm.

Methods: Consecutive patients with recurrent VT despite antiarrhythmic drugs (AADs) and prior ablation, for whom percutaneous epicardial access was contraindicated, underwent open SurgAbl using intraoperative EAM guidance.

Results: Eight patients were included, among whom mean age was 63 ± 5 years, all were male, mean left ventricular ejection fraction was 39% ± 12%, and 2 (25%) had ischemic cardiomyopathy. Reasons for surgical epicardial access included dense adhesions owing to prior cardiac surgery, hemopericardium, or pericarditis (n = 6); or planned left ventricular assist device (LVAD) implantation at time of SurgAbl (n = 2). Cryoablation guided by real-time EAM was performed in all. Goals of clinical VT noninducibility or core isolation were achieved in 100%. VT burden was significantly reduced, from median 15 to 0 events in the month pre- and post-SurgAbl ( = .01). One patient underwent orthotopic heart transplantation for recurrent VT storm 2 weeks post-SurgAbl. Over mean follow-up of 3.4 ± 1.7 years, VT storm-free survival was achieved in 6 (75%); all continued AADs, although at lower dose.

Conclusion: Surgical mapping and ablation of refractory VT with use of contemporary EAM is feasible and effective, particularly among patients with contraindication to percutaneous epicardial access or with another indication for cardiac surgery.
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June 2021

Two Year, Single Center Clinical Outcome After Catheter Ablation For Paroxysmal Atrial Fibrillation Guided by Lesion Index.

J Atr Fibrillation 2018 Jun-Jul;11(1):1760. Epub 2018 Jun 30.

Colorado Springs Cardiology 2222 N Nevada Ave, Suite 4007 Colorado Springs, CO 80907 USA.

Background: This study describes the use of lesion index (LSI) as a direct measure to assess the adequacy of ablation lesion formation with force-sensing catheters in ablation of paroxysmal atrial fibrillation (PAF). LSI is calculated by the formula:LSI = CF (g) ×Current (mA) ×Time (sec).

Methods: Fifty consecutive patients with PAF underwent pulmonary vein (PV) isolation using a catheter dragging technique and targeting different LSI values in different anatomical areas.A force-sensing ablation catheter was used to continuously measure contact force (CF) and guide radiofrequency ablation (RF) lesion formation. Ablation lesions were delivered to achieve an LSI value of 5.0 in posterior locations, 5.5 in anterior locations and 6.0 in the regionbetween the left atrial appendage and left superiorpulmonary vein ridge. Force-time Integral (FTI) was not used to evaluate lesion formation.

Results: A single center, retrospective analysis was performed with 196/198 (99%) PVs acutely isolated. The mean procedure time was 134 ± 34 mins and the mean fluoroscopy time was 7.8 ± 3.2 mins. At a mean follow up of two years, 43/50 (86%) of patients were in normal sinus rhythm with no documented recurrences of atrial fibrillation.

Conclusion: LSI can be used to guide the placement of durable lesion formation with RF ablation using CF catheters in patients with PAF.
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June 2018

A novel 3D anatomic mapping approach using multipoint high-density voltage gradient mapping to quickly localize and terminate typical atrial flutter.

J Interv Card Electrophysiol 2017 Sep 22;49(3):319-326. Epub 2017 Jul 22.

Colorado Springs Cardiologists, Colorado Springs, CO, USA.

Purpose: The purposes of the study were to evaluate and characterize the cavotricuspid isthmus using multipoint high density voltage gradient mapping (HD-VGM) to see if this would improve on current ablation techniques compared to standard cavotricuspid isthmus ablation techniques.

Methods: Group 1, 25 patients who underwent ablation using standard methods of 3D mapping and ablation, was compared to group 2, 33 patients undergoing ablation using HD-VGM and ablation. Using this method, we are able to identify the maximum voltage areas within isthmus and target it for ablation. Total procedure times, ablation times and number of lesions, distance ablated, and fluoroscopy times were compared.

Results: Fifty-eight patients were included in this study. Compared to group 1, in group 2, HD-VGM decreased the total ablation time 18.2 ± 9.2 vs 8.3 ± 4.0 min (p < 0.0001), total ablation lesions 22.7 ± 18.8 vs 5.5 ± 4.2 (p < 0.0001), and the length of the ablation lesions was significantly shorter 47.0 mm ± 13 mm vs 32.6 mm ± 10.0 mm (p < 0.0001). While the average length of the CTI was similar, 47.0 mm ± 13 mm vs 46.1 mm ± 10.0 mm (p 0.87), in group 2, only 71% of the isthmus was ablated.

Conclusion: Multipoint high density voltage gradient mapping can help identify maximum voltage areas within the isthmus and when ablated can create bidirectional block with decreased ablation times and length of the lesion.
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September 2017