Functional Characterization of Epicardial Beating Heart Radiofrequency Left Atrial Maze

Back to Annual Meeting
Back to Program

---

Takeyoshi Ota¹, David Francischelli², Douglas Hettrick², David Schwartzman³, Marco A. Zenati¹.
¹Cardiac Surgery, Heart, Lung and Esophageal Surgery Institute. University of Pittsburgh, Pittsburgh, PA, USA, ²Medtronic, Inc., Minneapolis, MN, USA, ³Cardiovascular Institute, University of Pittsburgh, Pittsburgh, PA, USA.

Background: The cut-and-sew Maze procedure is the gold standard for surgical treatment of atrial fibrillation but is associated to long-term impairment of left atrial (LA) transport function. We have developed a bipolar irrigated radiofrequency ablation device for epicardial beating heart LA ablation. We hypothesized that, as opposed to the cut-and-sew Maze, the epicardial radiofrequency LA Maze would result in minimal acute changes in LA hemodynamics using a catheter-based pressure-volume analysis.
Methods: Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into LA and left ventricle (LV). Using the device, epicardial atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of posterior left atrium and atrial appendage (LAA) myocardium. Simultaneous left heart pressure-volume was acquired prior to ablation, after LAA ablation alone, and after all ablation (with and without appendage occlusion). Functional 27 indices were assessed including: Av (V loop area), Aa (A loop area), Ep (linear slope of the passive filling phase), Vr (refill volume), Ees (end-systolic elastance slope), Eed (end-diastolic elastance slope), Vc (conduit volume). The encircling lesions were assessed with pacing of distal myocardium to confirm electrical isolation.
Results: Complete electrical isolations were achieved in all lesions. The electrical isolation of LAA did not exert any significant effect on LA and LV functions. The physical LAA isolation did not also have any affect except the slight increase in the LA Ep (p<0.05). There was no significant difference in all measured indices after all ablation. At autopsy, there was no damage to the surrounding structures such as the circumflex coronary artery. Transmural ablation was histologically proven in all lesions.
Conclusion: Epicardial radiofrequency beating heart LA Maze was safe and effective in producing transmural ablations. Electrical or physical LAA isolation and LA ablation did not significantly have an influence on acute LA or LV mechanical functions in a healthy porcine heart. Further studies are warranted in a chronic survival model.

Left Atrial Mechanical Function by Stage (*p<0.05; versus stage1)

Stage	1: baseline	2: temporary LAA occlusion	3: after LAA ablation with LAA occlusion	4: after LAA ablation without LAA occlusion	5: after all ablation without LAA occlusion	6: after all ablation with LAA occlusion
Av(ml·mmHg)	25±32	47±66	47±49	38±52	19±9	34±17
Ep(mmHg/ml)	0.57±0.27	0.90±0.83	0.74±0.35	0.48±0.18	0.80±0.25	1.02±0.30*
Vr (ml)	2.9±1.1	2.9±1.4	2.4±1.7	2.8±0.7	2.0±1.4	2.1±1.6
Eed (mmHg/ml)	0.31±0.41	0.49±0.51	0.16±0.23	0.41±0.13	0.50±0.23	0.62±0.13
Aa (ml·mmHg)	28±22	53±60	46±31	31±16	15±10	38±43
Es(mmHg/ml)	0.61±0.25	0.49±0.12	0.30±0.19	0.38±0.17	0.59±0.26	0.52±0.22
Vc (ml)	-0.20±16	-8.54±24	-8.80±24	-8.62±21	7.45±14	2.56±16

---

Back to Annual Meeting
Back to Program