Effect of heating on pulmonary veins: how to avoid pulmonary vein stenosis

INTRODUCTION: The success of radiofrequency energy catheter ablation for the treatment of patients with paroxysmal or chronic atrial fibrillation has been complicated by postablation development of pulmonary vein (PV) stenosis. The acute effect of heat on PV structure has not been well characterized. The aim of this study was to characterize the effects of hyperthermic exposure on PVs and to determine the critical temperature at which PV stenosis would be observed. METHODS AND RESULTS: The main PVs of acutely explanted canine hearts were identified, isolated, and dissected from the left atria. Measurements of the diameter of 3-mm PV rings were obtained at baseline and after hyperthermic exposure at 60 degrees C, 65 degrees C, 70 degrees C, and 80 degrees C. Mechanical behavior of PVs was studied by examining the stress-strain relationship of each PV specimen after heat exposure at different temperature settings. Twenty-eight PVs samples from 15 dogs (1-3 PVs/dog) were obtained and had a mean circumference of 8.7 +/- 2.3 mm at baseline. After heating to 60 degrees C, 65 degrees C, 70 degrees C, and 80 degrees C, the mean PV circumference was 9.2 +/- 2.3 mm (P = NS vs baseline), 6.8 +/- 2.3 mm (P < 0.0001), 4.2 +/- 1.5 mm (P < 0.0001), and 4.2 +/- 0.8 mm (P < 0.0001), respectively. The stress-strain curves of PV specimens were shifted to the left upon exposure to higher temperatures, indicating loss of compliance of PVs due to heat exposure. Histology showed loss of typical collagen matrix above 60 degrees C. CONCLUSION: Significant acute heat-induced contraction of PVs at zero-tension state was observed between 60 degrees C and 65 degrees C. This change was associated with collagen denaturation.     

Identification of pulmonary vein potentials by differential site atrial pacing in patients with paroxysmal atrial fibrillation: enhanced detection by pulmonary vein pacing

INTRODUCTION: Pulmonary vein (PV) isolation may cure paroxysmal atrial fibrillation (PAF); however, identification of PV potentials may be difficult in sinus rhythm. Studies have suggested that atrial pacing may improve the identification of PV potentials. METHODS AND RESULTS: In 25 consecutive patients who underwent PV isolation for PAF, the results of pacing from the distal PV, distal and proximal coronary sinus, and high right atrium compared to sinus rhythm were analyzed to determine the most effective pacing site for identification of PV potentials. The percentage of confirmed PV potentials and the longest interval between atrial and PV potentials in each PV were compared during differential site pacing and sinus rhythm. PV potentials were confirmed in 63 (82%) of 77 PVs that could be mapped during the complete pacing protocol and during sinus rhythm. Distal PV pacing identified significantly more PV potentials (left upper pulmonary vein [LUPV] 100%, left lower pulmonary vein [LLPV] 84%, right upper pulmonary vein [RUPV] 80%, right lower pulmonary vein [RLPV] 53%) compared to other pacing sites and sinus rhythm. Among atrial pacing sites, those ipsilateral to the PV being mapped were the most effective for identifying PV potentials. The intervals between atrial and PV potentials were significantly longer during distal PV pacing than pacing at other sites (LUPV 81.6 +/- 26.2 ms, LLPV 61.4 +/- 26.1 ms, RUPV 59.7 +/- 33.2 ms, RLPV 39.7 +/- 26.7 ms). CONCLUSION: (1) Distal PV pacing was most effective for identifying PV potentials. (2) The interval between atrial and PV potentials was longest during distal PV pacing.     

Right pulmonary vein potentials recorded from the posterior right atrial endocardium: human case report and validation in a porcine model

A 33-year-old woman underwent successful catheter ablation of an atrial tachycardia emanating from deep within a large right superior pulmonary vein (RSPV). A previous ablation attempt in this patient had failed, during which radiofrequency energy applications were made to the posterior right atrium only. The mistaken impression of a right atrial source for this tachycardia was due to RSPV potentials that were recorded during mapping in a region of the posterior right atrium contiguous to the vein ("contiguity region"). To further evaluate this, we performed activation mapping and radiofrequency ablation in atria of healthy pigs. Similar to the reported case, "biatrial" potentials were recorded from both left and right aspects of the contiguity region. Radiofrequency energy application altered only the potential emanating from the atrium in which the lesion was applied. Histologic analysis confirmed that the lesion was limited to this atrium. It is concluded that, due to their proximity, electrical activity in the RSPV may be recorded from certain areas of the posterior right atrium, and vice versa. In the reported case of left atrial tachycardia, this led to the mistaken impression of right atrial tachycardia.     

New cryotechnology for electrical isolation of the pulmonary veins

INTRODUCTION: Creation of radiofrequency lesions to isolate the pulmonary veins (PV) and ablate atrial fibrillation (AF) has been complicated by stenosis of the PVs. We tested a cryoballoon technology that can create electrical isolation of the PVs, with the hypothesis that cryoenergy will not result in PV stenosis. METHODS AND RESULTS: Lesions were created in 9 dogs (weight 31-37 kg). Cryoenergy was applied to the PV-left atrial (LA) interface. Data collected before and after ablation included PV orifice size, arrhythmia inducibility, electrogram activity, and pacing threshold in the PVs. Tissue examination was performed immediately after ablation in 3 dogs and after 3 months (4.8 +/- 1.0) in 6 dogs. After ablation there was no localized P wave activity in the ablation zone and no LA-PV conduction. Before ablation, the pacing threshold was 1.9 +/- 1.1 mA in each PV. After ablation, the pacing threshold increased significantly to 7.2 +/- 1.8 mA, or capture was not possible. Burst pacing did not induce any sustained arrhythmias. Most dogs had hemoptysis during the first 24 to 48 hours. Acute tissue examination revealed hemorrhagic injury of the atrial-PV junction that extended into the lung parenchyma. After recovery, the lesions were circumferential and soft with no PV stenosis. Histologic examination revealed fibrous tissue with no PV-LA interface thickening. CONCLUSION: This new cryoballoon technology effectively isolates the PVs from LA tissue. No PV stenosis was noted. Acute tissue hemorrhage and hemoptysis are short-term complications of this procedure. After 3 months of recovery, cryoablated tissue exhibits no collagen or cartilage formation.     

Ablation of superior pulmonary veins compared to ablation of all four pulmonary veins:

INTRODUCTION: Isolation of all pulmonary veins (PV) is advocated for treatment of paroxysmal atrial fibrillation (PAF). However, the superior PVs are responsible for most AF triggers, whereas the inferior PVs carry the higher risk for ablation-induced ostial stenosis. The aim of this study was to compare a superior PV isolation approach with isolation of all PVs for treatment of PAF. METHODS AND RESULTS: Fifty-two patients with PAF were randomized to either left superior pulmonary vein (LSPV) isolation followed by additional isolation of the right superior pulmonary vein (RSPV) in case of AF recurrence (group A, n = 27) or isolation of all four PVs followed by a repeat procedure in case of recurrence (group B, n = 25). At 1-year follow-up, 11 patients (41%) in group A and 8 patients (32%) in group B had AF relapse (P = 0.55). No significant differences in AF relapse were detected between groups at 3 and 12 months (log rank = 0.36, P = 0.54) and by Cox proportional hazards model analysis (P = 0.62). Nonsignificant PV stenosis was detected in two patients from group B. Total radiofrequency energy delivery and fluoroscopy and procedure times were lower in group A: 8.9 +/- 1.4 minutes vs 25.6 +/- 3.7 minutes (P < 0.001), 22.2 +/- 6.8 minutes vs 62 +/- 10.3 minutes (P < 0.001), and 131.8 +/- 26.5 minutes vs 222.2 +/- 32.3 minutes (P < 0.001), respectively. CONCLUSION: A staged superior PVs isolation approach confers equal success rates but with reduced radiofrequency energy delivery and fluoroscopy and procedure times compared to isolation of all PVs at the initial ablation attempt.     

Incidence and predictors of pulmonary vein stenosis following catheter ablation of atrial fibrillation using the anatomic pulmonary vein ablation approach: results from paired magnetic resonance imaging

INTRODUCTION: There are currently no studies systematically evaluating pulmonary vein (PV) stenosis following catheter ablation of atrial fibrillation (AF) using the anatomic PV ablation approach. METHODS AND RESULTS: Forty-one patients with AF underwent anatomic PV ablation under the guidance of a three-dimensional electroanatomic mapping system. Gadolinium-enhanced magnetic resonance (MR) imaging was performed in all patients prior to and 8-10 weeks after ablation procedures for screening of PV stenosis. A PV stenosis was defined as a detectable (> or =3 mm) narrowing in PV diameter. The severity of stenosis was categorized as mild (<50% stenosis), moderate (50-70%), or severe (>70%). A total 157 PVs were analyzed. A detectable PV narrowing was observed in 60 of 157 PVs (38%). The severity of stenosis was mild in 54 PVs (34%), moderate in five PVs (3.2%), and severe in one PV (0.6%). All mild PV stenoses displayed a concentric pattern. Moderate or severe PV stenosis was only observed in patients with an individual encircling lesion set. Multivariable analysis identified individual encircling lesion set and larger PV size as the independent predictors of detectable PV narrowing. All patients with PV stenosis were asymptomatic and none required treatment. CONCLUSIONS: The results of this study demonstrate that detectable PV narrowing occurs in 38% of PVs following anatomic PV ablation. Moderate or severe PV stenosis occurs in 3.8% of PVs. The high incidence of mild stenosis likely reflects reverse remodeling rather than pathological PV stenosis. The probability of moderate or severe PV stenosis appears to be related to creation of individual encircling rather than encircling in pairs lesion.     

Tachycardia and bradycardia coexisting in the same pulmonary vein

During segmental isolation of the pulmonary veins (PVs) in a patient with paroxysmal atrial fibrillation, there was a PV bradycardia that was dissociated from the left atrium in a segment of the right superior PV, whereas the remaining segments showed passive activation of a PV fascicle during sinus rhythm. Rapid atrial pacing induced a PV tachycardia in the nonisolated fascicles, and the dissociated PV bradycardia persisted in a segment of the same PV. These observations indicate that PV fascicles are insulated from each other and that a dissociated PV rhythm does not necessarily indicate complete isolation of a PV.     

老年人阵发性心房颤动的导管消融治疗

为评价老年人阵发性心房颤动 (PAF)行导管消融治疗的可行性和疗效 ,选择药物无法控制或不能耐受的PAF患者 5 6例 ,男 4 1例、女 15例 ,年龄 6 5 .7± 10 .1(6 0～ 74 )岁 ,无器质性心脏病 4 6例 ,合并高血压 7例 ,高血压及糖尿病 1例 ,高血压及冠心病 1例 ,冠心病 1例。均经食管超声心动图检查排除左房血栓。据消融技术的演进及患者入选的时间顺序 ,采用不同的消融方法 (点消融术、超声球囊肺静脉电隔离术、肺静脉节段性消融电隔离术 )。 3～ 6个月后评价疗效。结果 :5 6例患者 ,5 5例完成消融术 :点消融术 4例 ,成功 1例 ,无效 2例 ,心包积血 1例 ;超声球囊肺静脉电隔离术 14例 ,成功 7例 ,有效 5例 ,无效 2例 ,无肺静脉狭窄 ;肺静脉节段性消融电隔离术 37例 ,成功11例 ,有效 2 3例 ,无效 3例 ,左下肺静脉开口 >30 %狭窄 1例。结论 :导管消融治疗老年人PAF是安全有效的 ,肺静脉电隔离术使疗效明显提高 ,但仍未令人满意。     

Left atrial flutter after radiofrequency catheter ablation of focal atrial fibrillation

We report an arrhythmic complication in two patients in whom a procedure directed at isolating one or two pulmonary veins had been performed. The complication was related to pulmonary vein disconnection scars after ablation. Both patients developed new clinical tachycardia (atypical atrial flutter) secondary to a reentrant phenomena in the vicinity of a previously ablated pulmonary vein.     

房颤患者环肺静脉前庭射频消融路径的分析

目的比较房颤患者中3种不同环肺静脉前庭射频消融路径的消融成功率。方法回顾性分析解放军总医院心血管内科2015年6月至2017年6月住院房颤患者173例,根据射频消融线所在区域分为心房前庭组61例、肺静脉前庭组47例和前庭组65例,比较3组患者手术时间、X线曝光时间和消融时间,以及穿刺房间隔后、术后即刻和术后24 h血浆中C反应蛋白(CRP)、氨基末端B型脑钠肽前体(NT-proBNP)和白细胞介素-6(IL-6)水平。应用SPSS 17.0统计软件对数据进行分析。组间比较采用单因素方差分析、秩和检验或χ~2检验。结果所有患者在消融过程中达到完全电隔离的即刻成功率为84.39%(146/173)。心房前庭组患者消融时间明显长于肺静脉前庭组患者[(120.67±13.12)vs(90.17±6.95)min],差异有统计学意义(P0.05)。相比穿刺房间隔后,3组患者术后即刻和术后24 h IL-6水平升高,肺静脉前庭组患者术后24 h NT-proBNP水平升高;肺静脉前庭组患者术后24 h CRP水平相比心房前庭组患者[(1.99±1.09)vs(0.40±0.29)mg/L]升高,差异均具有统计学意义(P0.05)。161例随访12个月,12例失访,失访率为6.94%(12/173)。27例房颤复发,手术成功率为83.23%(134/161),其中心房前庭组手术成功率[89.83%(53/59)vs 73.33%(33/45)]高于肺静脉前庭组,差异具有统计学意义(P0.05)。结论房颤患者不同环肺静脉前庭射频消融路径中,心房前庭侧消融路径优于肺静脉前庭消融路径。     

Double multielectrode mapping catheters facilitate radiofrequency catheter ablation of focal atrial fibrillation originating from pulmonary veins

INTRODUCTION: Several reports have demonstrated that focal atrial fibrillation (AF) may arise from pulmonary veins (PVs). The purpose of this study was to investigate the safety and efficacy of using double multielectrode mapping catheters in ablation of focal AF. METHODS AND RESULTS: Forty-two patients (30 men, 12 women, age 65+/-14 years) with frequent attacks of paroxysmal AF were referred for catheter ablation. After atrial transseptal procedure, two long sheaths were put into the left atrium. Two decapolar catheters were put into the right superior PV (RSPV) and left superior PV (LSPV), or inferior PVs if necessary, guided by pulmonary venography. All the patients had spontaneous initiation of AF either during baseline (2 patients), after isoproterenol infusion (8 patients) or high-dose adenosine (2 patients), after short duration burst pacing under isoproterenol (14 patients), or after cardioversion of pacing-induced AF (16 patients). The trigger points of AF were from the LSPV (12 patients), RSPV (8 patients), and both superior PVs (19 patients). The trigger points from PVs (total 61 points) were 18 (30%) in the ostium of PVs and 43 inside the PVs (9 to 40 mm). After 6+/-3 applications of radiofrequency energy, 57 of 61 triggers were completely eliminated, and the other 4 triggers were partially eliminated. During a follow-up period of 8+/-2 months, 37 patients (88%) were free of symptomatic AF without any antiarrhythmic drugs. Twenty patients received a transesophageal echocardiogram, and 19 showed small atrial septal defects (2.8+/-1.2 mm) with trivial shunt. Fifteen defects closed spontaneously 1 month later. CONCLUSION: The technique using double multielectrode mapping catheters is a relatively safe and highly effective method for mapping and ablation of focal AF originating from PVs.     

心房颤动冷冻消融方法的应用进展

肺静脉隔离是心房颤动（房颤）导管消融的基石,冷冻球囊是专门为肺静脉解剖结构设计的工具,应用冷冻球囊 导管进行肺静脉隔离（PVI）的有效性和安全性获得了临床研究证实,国内外指南都已将冷冻球囊消融作为房颤消融 PVI的标准疗法。冷冻球囊消融具有持久肺静脉隔离、安全性高、操作简便、患者感受好、学习曲线短等优势,因此, 近10年在临床得以迅速普及应用。随着技术的不断创新和临床研究的深入,冷冻球囊消融疗法也在不断拓展。文 章就房颤冷冻球囊消融方法及应用进展进行论述。     

Maintenance of atrial fibrillation by pulmonary vein tachycardia with ostial conduction block: evidence of an interpulmonary vein electrical connection

We report a case of a 56-year-old man with paroxysmal atrial fibrillation who underwent segmental, ostial pulmonary vein (PV) isolation while in arrhythmia. During isolation of the left superior PV (LSPV), organized electrical activity was seen within the vein, suggestive of a PV tachycardia with a cycle length of 90 ms. Simultaneously, organized electrical activity with a cycle length of 180 ms was seen in the left inferior PV (LIPV), suggestive of 2:1 conduction between the LSPV and the LIPV. Isolation of the LIPV resulted in conversion to sinus rhythm, while confirming isolation of the LSPV by the presence of ongoing PV tachycardia in this vein. This case demonstrates a direct electrical connection between the ipsilateral left PVs, leading to maintenance of atrial fibrillation.