Address for correspondence:
Xi Li MD. PhD
Department of Cardiology, Wuhan Asia Heart Hospital
753 Jinghan Road, Wuhan, Hubei, China, 430000
Email: magiclx1234@163.com
Jinlin Zhang MD. PhD
Department of Cardiology, Wuhan Asia Heart Hospital
753 Jinghan Road, Wuhan, Hubei, China, 430000
Email: zjl1974@yeah.net
Yanhong Chen MD. PhD
Department of Cardiology, Wuhan Asia Heart Hospital
753 Jinghan Road, Wuhan, Hubei, China, 430000
Email: sailorsdog@gmail.com
INTRODUCTION
Left atrial appendage (LAA) has been known as a source of focal atrial tachycardias (AT)1, 2。Radio-frequency (RF) energy based focal ablation of these arrhythmias was a common strategy in most cases. However, catheter ablation in these foci remains challenging due to the complexity of the LAA anatomy. Sometimes an epicardial approach is an alternative when endocardial ablation of LAA fails2. Cryo-balloon based LAA isolation may be considered before epicardial access3。We report a patient with focal atrial tachycardia originated in the tip of a LAA ligation stump (he underwent a heart valve mitral bio-prostheses replacement and had his LAA ligated during the operation years ago), who, being refractory to focal RF ablation, received a LAA isolation using a cryo-balloon which successfully terminated the tachycardia and converted the patient to sinus rhythm.
Key words: atrial tachycardia; left atrial appendage stump; cryo-ablation; anti-coagulation, Rhythmia system
Case description
A 70-year-old man presented with recurrent drug-refractory atrial tachycardia, who had underwent Mitral valve replacement, Tricuspid valvuloplasty, and ligation of the LAA years ago. The 12-lead electrocardiography demonstrated long RP tachycardia with a negative P wave in I and aVL, a positive P wave in inferior leads and a positive P wave in V1 (Figure 1A ). The coronary sinus mapping revealed a distal-to-proximal atrial activation sequence during the AT (Figure 1B ). After trans-septal puncture, an Orion basket catheter (64 electrodes of 0.4 mm2 area; 2.5 mm spacing) was placed into the left atrium. Using a ultra-high resolution mapping system, (Rhythmia system), 16947 points were achieved which revealed that the earliest atrial activation was inside the tip of the LAA stump (Figure 1C ). Angiographic revealed the LAA ligation stump (Figure 1D ). Then, an irrigated tip 3.5 mm ablation catheter (Thermocool SF, Biosense Webster, Diamond Bar, CA, USA) was introduced to the earliest activation point (Figure 2 ). Unfortunately the catheter mechanically terminated the tachycardia, and the atrial tachycardia could not be induced by programmed stimulations. RF energy was given under sinus rhythm with the energy of 10-15 W at the earliest activation spot. However, we were not sure about the end point due to a failure to induce the atrial tachycardia. We were also concerned about the potential risk of pericardial tamponade of a fragile LAA stump wall during ablation, so ablation time was limited. But the atrial tachycardia recurred 2 days later. A second mapping confirmed the tachycardia was originated from the same foci. Concerning the difficulties of focal ablation strategy, we decided to electrically isolate the whole LAA stump using a second generation 28-mm cryo-balloon (CB2; Arctic Front Advance, Medtronic, USA). After placing the inner lumen circular map catheter (Achieve 15mm, Medtronic Inc., Minneapolis, USA) into the LAA stump, the CB was inflated and the complete LAA occlusion was confirmed using angiography. During the CB ablation, the atrial tachycardia terminated and the sinus rhythm was restored (Figure 3 ). After ablation, pacing was performed to verify the left atrial appendage stump electrical isolation (Figure 3C ).The patient was put on a continual oral anticoagulation after the procedure. Our follow-up of 6 months confirmed no recurrence of the tachycardia, nor any ischemic embolism.