How Do Balloon Technologies Compare with New Generation RF Ablation Systems?
“I will be comparing existing balloon technologies versus new radiofrequency (RF) ablation systems, including the benefits and efficacy of the cryoballoon1 and laser balloon2 in patients with atrial fibrillation (AF),” Hiroshi Nakagawa, MD, PhD (University of Oklahoma, Oklahoma City, OK) told AF Symposium News ahead of his presentation.
“The advantage of the balloon technology is that it’s a single-shot operation, providing an easy and quick procedure compared to point-by-point radiofrequency ablation,” said Dr. Nakagawa. “However, the wall thickness of the left atrium around the pulmonary vein (PV) is different, thinner and much thicker in the anterior/superior wall.” These balloon ablation systems require circumferential balloon contact to the atrial wall and ablation energy (cryothermia or laser) is delivered equally around the pulmonary vein circumference, producing similar lesion depths around the circumference. This may result in excessive ablation lesions in the posterior wall (may increase the risk of collateral injury, such as esophageal lesions and phrenic nerve injury) and inadequate lesions (nontransmural necrosis) in the anterior/superior wall of the left atrium.
He continued: “In order to get good balloon contact, you need to push the catheter, but it may increase contact force to the posterior wall (where the thin wall is located) and not increase contact formce on the anterior/superior wall (where the thicker myocardium is located, especially along the left atrial appendage ridge).
Nakagawa and colleagues have shown that, in canine beating heart studies, RF lesion depth and diameter were predicted accurately using a new logarithmic formula using contact force (CF), RF power and application time (Force-Power-Time Formula, FPTF). 3
Click image to expand
They tested the ability of FPTF to guide ipsilaterial pulmonary vein isolation (Ip-PVI) in a single RF encirclement in AF patients. In 43 patients with paroxysmal atrial fibrillation, Ip-PVI was performed using a 7.5 French CF catheter (ThermoCool SmartTouch, Biosense Webster) and the CARTO 3 system. Using FPTF, lesion depth was targeted at 4mm for posterior/inferior segments and 6 mm for anterior/superior segments along the PV circumference (Figure 1). RF was delivered until FPTF reached target depth or esophageal temperature reached 40 degrees C. To produce continuous lesions, RF sites (4-6 mm diameter tags) were connected. Radiofrequency parameters to obtain the target depth were as follows: average CF: median 15g (range 3-64g), power: 35W (17-50W), and time: 28 sec (6-93 sec). Total RF time for Ip-PVI was median 15 min (8.3-32 min) and circumference length was median 12.2 cm (8-16.5 cm). Complete isolation was obtained by the first encirclement in 77/86 (90%) Ip-PVs. Most gaps were located at LA appendage ridge (with low CF<5g) data-preserve-html-node="true" data-preserve-html-node="true" or mid-posterior righ Ip-PVI. No steam pop occurred. After Ip-PVI was completed, adenosine produced PV reconnection in only 4/86 (5%) Ip-PVIs. During preliminary follow-up (2-11 months), 42/43 (98%) patients had no AF/AT. 4 Nakagawa and colleagues concluded that FPTF guidance produced complete ipsilateral PV isolation by a single encirculment in 90% using relatively short RF time, targeting a lesion depth of 4 mm for the posterior/inferior segments and 6 mm for the anterior/superior segments.
- Metzner A, Reissmann B, Rausch P, et al. One-year clinical outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon. Cir Arrhythm Electrophysiol. 2014;7:288-292.
- Bordignon S, shun KR, Gunawardene M, et al. Energy titration strategies with the endoscopic ablation system: lessons from the high-dose vs. low-dose laser ablation study. Eurospace. 2013 May; 15(5):685-9
- Nakagawa H, Yamashiro K, Duytschaiver M, et al. High Incidence of Ipsilateral Pulmonary Vein Isolation by First Encirclement Using New Force-Power-Time Formula with Shot Radiofrequency Time in ATrail Fibrallation Patients. Abstract presented at the 2015 Heart Rhythm Society Scientific Sessions.