Acute results of transvenous cryoablation of supraventricular tachycardia (atrial fibrillation,atrial flutter,Wolff-Parkinson-White syndrome,atrioventricular nodal reentry tachycardia)

INTRODUCTION: Radiofrequency (RF) catheter ablation currently is used for treatment of cardiac arrhythmias. Although the success rate is high for almost all supraventricular tachycardias (SVT), this technique has some drawbacks, especially when pulmonary veins (PV) are targeted for treatment of atrial fibrillation (AF). Additionally, new techniques for isolation of the PVs have the drawback that they can be used only for PV isolation and not for routine treatment of other SVTs. The aim of this study was to report on the safety and efficacy of a new cryoablation system for treatment of all SVTs. METHODS AND RESULTS: Forty-nine patients with SVT (38 men; age 48 years, range 23-76) were enrolled in the study. Five patients were withdrawn from the study before they underwent cryoablation. The remaining 44 patients were treated with cryoablation (22 AF, 15 atrial flutter, 3 accessory pathway, 2 AV nodal reentrant tachycardia, 1 AV junction ablation for permanent AF, 1 atrial tachycardia). Cryoablation was performed with the CryoCor cryoablation system, which uses a precooling system and N2O as a refrigerant. The number of freezes applied varied according to the index arrhythmia treated. Successful isolation of PVs was performed in 20 of (96%) 21 AF patients and 53 of 55 veins. The overall acute success was 98% (43/44). Fifty-three PVs were isolated (2.5/patient). The success rate was 100% (23/23) for right-sided procedures. The average and nadir temperatures reached in right-sided and left-sided procedures were -77 degrees C and -80 degrees C and -75 degrees C and -78 degrees C, respectively. No acute PV stenosis was seen. CONCLUSION: This novel cryoablation system appears to be safe and can successfully treat different types of SVTs, including AF. Isolation of PVs is possible without producing stenosis. Despite the high blood flow in the right atrial isthmus and PVs, bidirectional conduction block can be achieved.     

Isolation of pulmonary veins using a transvenous curvilinear cryoablation catheter: feasibility, initial experience, and analysis of recurrences

INTRODUCTION: Pulmonary vein isolation (PVI) using focal cryothermal catheters is safe and moderately effective, but associated with long procedure times. We hypothesized that a linear freezing segment could shorten fluoroscopic and procedure times. We report our initial experience with a novel circular cryothermal catheter. METHODS AND RESULTS: Complete PV isolation (PVI) was achieved in 41 of 45 PVs by cryoablation (91%) in 18 patients who underwent Lasso-guided cryothermal using a novel 7 F circular catheter (2.5 +/- 0.7 veins per patient). A mean of 27.2 +/- 11 applications per patient (9.2 +/- 4.7 per vein) with a mean temperature -79.8 +/- 4 degrees C were delivered. Recorded temperatures did not predict complete or incomplete isolation. Focal cryothermal ablation using a 7 F 4-mm tip was required in the remainder for isolation. During 14.8 +/- 6.2 month follow-up, 4 (22%) had no recurrence of AF, and 7/18 (39%) had >90% reduction in symptoms without antiarrhythmic agents (AAA). Computed tomography scans at 3 months showed no stenosis (14.1 +/- 2.5 mm, 13.9 +/- 2.4 mm; P = 0.2). Eight patients underwent repeat ablation. Mapping demonstrated 13 of 14 (93%) previously isolated veins had recovery of over 64 +/- 24% of the ostium. All were successfully isolated with RF and 7 of 8 were arrhythmia free 6.0 +/- 2.9 months after ablation. Overall, 14 of 18 (78%) patients had their arrhythmia clinically controlled without drugs after one or two procedures. CONCLUSIONS: Our initial experience demonstrates safety and feasibility of circular cryothermal ablation with less fluoroscopic and procedure times as compared to focal cryothermy. As with RF, complete and permanent isolation of the PVs is not easily achieved. Reducing heat load due to PV flow may improve results.     

导管冷冻消融隔离肺静脉治疗心房颤动

目的探讨导管冷冻消融隔离肺静脉治疗心房颤动的临床疗效？方法回顾性分析15例进行冷冻消融治疗的心房颤动患者的临床资料．着重分析冷冻消融治疗的术前准备、手术方法、手术结果、术后并发症以及随访结果。结果存Lasso标测电极指导下了．用Arctic Circler冷冻消融导管在肺静脉开口附近进i了冷冻消融,隔离肺静脉直至肺静脉电位消失。13例阵发性心房颤动患者中．10例术中维持窦性心律,3例术中有短阵心房颤动发作,但均能自行终止。2例持续性心房颤动患者,1例于冷冻消融进行中终止心房颤动,1例未能在消融治疗中终止．在消融完成后行体外直流电复律1次,成功转为窦性心律,消融成功率为93．3ck（14／15）。共对15例心房颤动患者的54根肺静脉进行了电隔离,其中36根肺静脉单用环状冷冻导管消融4次～6次即能达到肺静脉的完全电隔离．18根肺静脉用环状冷冻导管消融后,需用普通射频消融导管在环形冷冻线上补点消融后才成功隔离肺静脉。术中、术后均无急性肺静脉狭窄等严重并发症发生。随访6个月～10个月,11例临床症状得到改善,无心房颤动复发,其中4例需服用抗心律失常药维持窦性心律,4例心房颤动复发。消融后即刻选择性肺静脉造影和术后6个月核磁共振扫描检查均未发现肺静脉狭窄。结论导管冷冻消融隔离肺静脉是治疗心房颤动的有效方法。     

Catheter cryoablation of the atrioventricular node in patients with atrial fibrillation: a novel technology for ablation of cardiac arrhythmias

INTRODUCTION: Recent animal studies demonstrated the feasibility and safety of applying percutaneous catheter cryoablation technology for ablation of arrhythmogenic sites. The studies also showed that reversible "ice mapping" can be performed before creating permanent lesions. We investigated the feasibility and safety of applying this new technology in man. METHODS AND RESULTS: Cryoablation of the AV node (AVN) using a 9-French quadripolar catheter with a 4-mm electrode tip was attempted in 12 patients (mean age 67.8 +/- 11.4 years) with refractory atrial fibrillation. Whereas technical issues prevented adequate tissue contact in two patients, complete AVN block was obtained in the remaining 10 patients after 4.8 +/- 1.9 cryoapplications lasting 5.5 +/- 0.2 minutes resulting in temperatures of -58.1 degrees +/- 5.4 degrees C. In all patients with sinus rhythm at the time of the procedure, cryomapping at warmer temperatures induced reversible AVN block and allowed confirmation of a successful site before definitive ablation. Intracardiac echocardiography was performed in three patients and allowed visualization of the cryocatheter-endocardial contact and cryolesion formation. No major procedural complications were reported. After 6 months of follow-up, 8 of 10 initially successful patients remained in complete block; 1 had partial recovery of AVN conduction manifested by atrial fibrillation with a slow ventricular response, and 1 fully recovered AVN conduction. CONCLUSION: (1) Catheter cryoablation of the AVN can be performed safely in man. (2) Reversible cryomapping is feasible and may offer an advantage over radiofrequency ablation. (3) Cryocatheter-endocardial contact and cryolesion growth can be monitored with intracardiac echocardiography.     

经皮导管冷冻消融治疗阵发性心房颤动的临床应用

目的:探讨导管冷冻消融术治疗心房颤动的有效性及安全性.方法:对12例阵发性心房颤动患者进行冷冻消融治疗.评价导管冷冻消融术治疗心房颤动的急性成功率、术后并发症以及临床长期有效性.结果:12例阵发性心房颤动患者,共对44根肺静脉进行了冷冻消融,其中29根肺静脉单用环状冷冻导管消融4～6次即能达到肺静脉的完全电隔离,15根肺静脉用环状冷冻导管消融后,需用普通射频消融导管在环形冷冻线上补点消融后才成功隔离肺静脉.随访6～10个月,9例临床症状得到改善,无心房颤动复发,其中3例需服用抗心律失常药维持窦性心律.3例患者心房颤动复发.消融后即刻选择性肺静脉造影和术后6个月核磁共振扫描检查均未发现肺静脉狭窄.结论:经皮导管冷冻消融治疗阵发性心房颤动是安全、有效的,可作为治疗心房颤动的一种有效方法.     

Combined pulsed field ablation with ultra-low temperature cryoablation: A preclinical experience

Background

Combining pulsed field ablation (PFA) with ultra-low temperature cryoablation (ULTC) represents a novel energy source which may create more transmural cardiac lesions. We sought to assess the feasibility of lesions created by combined cryoablation and pulsed field ablation (PFCA) versus PFA alone.

Methods

Ablations were performed using a custom PFA generator, ULTC console, and an ablation catheter with insertable stylets. PFA was delivered in a biphasic, bipolar train. PFCA precooled the tissue for 30 s followed by a concurrent PFA train. Benchtop testing using Schlieren imaging and microbubble volume assessment were used to compare PFA and PFCA. PFA and PFCA lesions using pre-optimized and optimized ablation protocols were studied in 6 swine. Pre and post-ECGs were recorded for each ablation and a gross necropsy was performed at 14 days.

Results

Consistent with benchtop comparisons of heat and microbubble generation, PFA deliveries in the animals were accompanied by muscle contractions and significant microbubbles (Grade 2–3) visible on intracardiac echo while neither occurred during PFCA at higher voltage levels. Both PFA and PFCA acutely eliminated or highly attenuated (>80%) local atrial electrograms. Histology of PFA and PFCA lesions indicated depth up to 6–7 mm and nearly all lesions were transmural. Optimized PFCA produced wider cavotricuspid isthmus lesions with evidence of tissue selectivity.

Conclusion

A novel technology combining PFA and ULTC into one energy source demonstrated in-vivo feasibility for PFCA ablation. PFCA had a more favorable thermal profile and did not produce muscle contraction or microbubbles while extending lesion depth beyond cryoablation.     

Incidence of silent cerebral thromboembolic lesions after atrial fibrillation ablation may change according to technology used: comparison of irrigated radiofrequency, multipolar nonirrigated catheter and cryoballoon

AF Ablation Technologies and Silent Cerebral Ischemic Lesions. Introduction: Silent cerebral ischemic lesions have recently emerged as the most frequent complications after pulmonary vein isolation (PVI). To reduce thromboembolic complications, new types of catheters and energy source have been introduced in clinical practice. The study purpose is to compare the incidence of new silent cerebral ischemic events in patients with paroxysmal atrial fibrillation (PAF) undergoing PVI with different ablation technologies. Methods and Results: One hundred and eight patients (67% men; age 56 ± 9 years) with PAF were enrolled in a consecutive manner to undergo PVI performed with irrigated radiofrequency (RF) catheter (Group 1, 36 patients), multielectrode catheter (PVAC) associated with duty‐cycled RF generator (Group 2, 36 patients) and cryoballoon (Group 3, 36 patients). The protocol included a cerebral magnetic resonance imaging before and after the procedure. After PVI, the following patients showed new silent cerebral ischemic lesions at postprocedural cerebral MRI: 3 patients in Group 1 (8.3%), 14 patients in Group 2 (38.9%), 2 patients in Group 3 (5.6%). PVAC related to higher incidence of silent cerebral ischemic events compared to irrigated RF (P = 0.002) and cryoballoon (P = 0.001), whereas no statistical differences were found between irrigated RF catheter and cryoballoon groups (8.3% vs 5.6%, P = 0.5). At the multivariate analysis, the only independent predictor of new ischemic asymptomatic cerebral lesions after PVI was ablation performed with PVAC (OR 1.48 95% CI 1.19–1.62, P < 0.001). Conclusion: The incidence of silent cerebral lesions after PVI is different depending on technologies used: PVAC increases the risk of 1.48 times compared to irrigated RF and cryoballoon ablation. (J Cardiovasc Electrophysiol, Vol. 22, pp. 961‐968, September 2011)     

Haemodynamics of induced atrial fibrillation: a comparative assessment with sinus rhythm, atrial and ventricular pacing

The haemodynamics and myocardial lactate consumption during induced atrial fibrillation (AF) were studied in 10 patients with paroxysmal AF. Their mean age (+/- SD) was 61 +/- 5 years and none had clinical evidence of ischaemic or rheumatic heart disease. Compared with sinus rhythm, the onset of AF was associated with a reduction in systolic blood pressure (152 +/- 13 mmHg) in AF vs 169 +/- 23 mmHg in sinus rhythm, P less than 0.01). There was no consistent change in cardiac output at the onset of AF compared with sinus rhythm, but the cardiac output was lower compared with regular atrial pacing at rates similar to those of induced AF (3.85 +/- 0.76 vs 4.38 +/- 0.89 l min-1, P less than 0.02). Compared with sinus rhythm or rate-matched atrial pacing, AF was associated with an elevated pulmonary arterial pressure (24.2 +/- 5.6 mmHg in AF vs 17.9 +/- 14.4 mmHg in sinus rhythm, P less than 0.01) and pulmonary arterial wedge pressure (18.6 +/- 5.6 vs 9.7 +/- 3.9 mmHg, P less than 0.01). The haemodynamic changes during AF were similar to those seen during regular ventricular pacing at an equivalent rate, although the latter was associated with a lower systolic blood pressure (152 +/- 13 mmHg in AF vs 136 +/- 25 mmHg in ventricular pacing, P less than 0.05) and higher right atrial pressure (8.2 +/- 4.4 vs 11.5 +/- 7.5 mmHg respectively, P less than 0.05), presumably due to the deleterious effects of cannon 'a' waves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Initiation of ventricular fibrillation by atrial fibrillation

We report the case of a patient who developed spontaneouslya ventricular fibrillation during atrial fibrillation, 8 minafter a perfusion of isoproterenol was stopped Two mechanismscould explain the ventricular arrhythmia: silent ischaemia anda long-short cycle sequence just before ventricular fibrillation.     

老年原发性高血压并心房颤动患者左心房病变分析

【】目的 探讨老年原发性高血压合并房颤患者左心房病变情况,为临床治疗此类患者提供指导。方法 回顾分析老年原发性高血压患者合并房颤者110例,其中阵发性房颤者42例,非阵发性房颤68例。收集心脏超声断面图收缩期左心房前后径(LAD)和左室射血分数(LVEF)等资料,并进行比较。结果 非阵发性房颤组LAD显著增大(P<0．05),房颤的发生与维持与血压、年龄及LAD相关。结论 老年原发性高血压患者合并房颤者可出现显著的左心房扩大,年龄、高血压、左心房扩大均为心房颤动的危险因素。     

Impact of biphasic electrical cardioversion of atrial fibrillation on early recurrent atrial fibrillation and shock efficacy

INTRODUCTION: Early recurrent atrial fibrillation (ERAF) after external cardioversion of atrial fibrillation (AF) occurs in 12% to 26% of patients. Whether biphasic cardioversion has an impact on the incidence of ERAF after cardioversion of AF is unclear. METHODS AND RESULTS: Consecutive patients (n = 216, mean age 66 years, 71% male, 88% with structural cardiovascular disease or hypertension) underwent cardioversion with a biphasic (Bi) or monophasic (Mo) shock waveform in randomized fashion. Energies used were 120-150-200-200 Ws (Bi) or 200-300-360-360 Ws (Mo). The two study groups (Bi vs Mo) did not differ with regard to age, sex, body mass index, underlying cardiovascular disease, left atrial diameter, left ventricular ejection fraction, duration of AF fibrillation, and antiarrhythmic drug therapy. Mean delivered energy was significantly lower in the Bi group (Bi: 186 +/- 143 Ws vs Mo: 324 +/- 227 Ws; P < 0.001). Overall incidence of ERAF (AF relapse within 1 minute after successful cardioversion) was 8.9% and showed no difference between the two groups (Bi: 8.1% vs Mo: 9.7%, P = NS). Cardioversion was successful in 95.4% of patients. The success rate was comparable in both groups (Bi: 94.3% vs Mo 96.8%; P = NS). First shock efficacy did not differ between Bi and Mo (76.4% vs 67.7%; P = NS). Mean number of shocks were 1.4 shocks per patient in both groups. CONCLUSION: Biphasic cardioversion allows comparable success rates with significantly lower energies. However, the incidence of ERAF is not influenced by biphasic cardioversion. With the energies used, biphasic and monophasic shock waveforms are comparable with regard to first shock and cumulative shock efficacy.