Complete isolation of the pulmonary veins and posterior left atrium in chronic atrial fibrillation. Long-term clinical outcome

Aims: To evaluate the contribution of the posterior left atrium (LA)to chronic atrial fibrillation (AF). Methods and results: Twenty-seven patients with chronic-AF were studied. After pulmonaryvein (PV) isolation, the posterior-LA was isolated by ablationjoining the right- and left-PVs using an irrigated-tip catheter.Isolation was demonstrated by absent/dissociated posterior-LAactivity and the inability to pace the region. Ablation impactwas determined by the effect on cycle length (CL) and AF termination.Posterior-LA isolation was achieved using 35 ± 12 minof radiofrequency with total fluoroscopic and procedural durationsof 64 ± 16 and 199 ± 46 min, resulting in abolitionof electrograms (n = 21) or autonomous activity (n = 6; CL 820± 343 ms). AFCL increased from 156 ± 28 ms to162 ± 27 ms with PV-isolation and to 175 ± 32ms by posterior-LA exclusion (P < 0.0001). AF persisted inall after PV-isolation and terminated in 5 (19%) during posterior-LA-isolation.After 10 ± 6 months, 12 patients developed atrial tachycardia(four) or AF (eight); four underwent repeat posterior-LA-isolation,while the others required additional ablation/antiarrhythmics.After 21 ± 5 months, 17 (63%) were in sinus rhythm followingposterior-LA-isolation. Conclusion: This study demonstrates the feasibility of complete posterior-LAexclusion by catheter ablation. This strategy results in maintenanceof sinus rhythm in 63% at 2 years follow-up.     

递进式个体化心房基质消融治疗心房颤动

目的 以肺静脉电学隔离为终点的心房颤动（房颤）消融术式的疗效难以令人满意。本研究旨在探索规范化的递进式个体化心房基质改良消融术治疗房颤的方法。方法 124例患者（男性96例,女性28例）,年龄27-76（53．6±8．7）岁。其中92例为阵发性房颤,32例为持续性／永久性房颤。若无自发房颤则在心房进行持续递增的快速刺激（频率200—600次／min）诱发房颤。均在非接触式标测观察房颤时心房激动情况,将最常激动部位做为房颤基质进行改良消融,并根据消融后重复等电位标测的结果作出递进式调整,直至房颤被终止不再被诱发。结果 在既不隔离肺静脉也不寻求碎裂电位的情况下,87．1％（108／124）的房颤消融转复为窦性心律,其余被转为非典型心房扑动（房扑）或房性心动过速（房速）。可将消融灶分为3种类型,其中以7字形的A型线性消融最关键,71．6％的阵发性房颤可被A型消融终止且不再被诱发,而68．8％的持续性／永久性房颤则需通过B型消融终止。随访（21．6±5．3）个月,90．3％（112／124）的患者不服药亦无房颤发生。其余9．7％（12／124）的患者有顽固性非典型房扑／房速,其中仅1．6％（2／124）的患者伴有阵发性房颤。结论 递进式的心房基质消融术可以将房颤有效地转复为窦性心律,并有满意的远期疗效。此种术式简单易行有望在NavX和Carto标测下复制。     

心房颤动左心房内线性消融后的非典型性心房扑动

目的　左心房线性消融治疗心房颤动 (AF)后的非典型性心房扑动 (AAF)值得引起重视。方法　 2 4例患者 (男性 2 0例 ,女性 4例 ) ,年龄平均 5 1 2± 10 9(2 2～ 6 7)岁 ,左心房内径 33 9± 5 5(2 2～ 4 2 )mm。其中阵发性AF(PAF) 19例 ,持续性AF 5例。均在非接触式标测的指导下在左、右肺静脉口外进行环行消融 ,并在顶部肺静脉口间及二尖瓣环峡部行线性消融。在AF终止后经冠状静脉窦进行程序刺激以检验效果并观察是否存在AAF。结果　全部 19例PAF患者中 ,18例的左心房内线性消融获即时成功 ,1例经体外电转复 ;5例持续性AF者有 4例在消融后电转复成功 ,1例未能转复。共有 5例诱发出左心房AAF ,1例被超速抑制 ,2例在左心房顶部左、右肺静脉口之间 ,2例在二尖瓣峡部消融终止了AAF。在随访 7 5± 7(1～ 30 )月 ,除在肺静脉口间消融成功的 2例之外 ,其余 3例AAF均复发 ,2例服抗心律失常药物控制可维持窦性心律为主 ,1例因为 4∶1AV传导无症状而不愿接受治疗。结论　在左心房内进行线性消融治疗房颤存在引发非典型性房扑的可能 ,所采用的消融导管类型可能对其也存在一定影响 ,值得重视     

Flutter localized to the anterior left atrium after catheter ablation of atrial fibrillation

INTRODUCTION: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation. METHODS: A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping. RESULTS: Fourteen patients (11 female, 65 +/- 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete -/+ or +/-/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 +/- 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 +/- 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low-amplitude, fractionated mid-diastolic potentials with long duration (200 +/- 80 msec) occupying 63 +/- 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility. CONCLUSION: Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area.     

中国经导管消融治疗心房颤动注册研究

目的分析截止2005年我国经导管消融治疗心房颤动(房颤)的整体情况和发展趋势。方法2006年3月向全国开展经导管消融治疗房颤的医院发出注册登记表,6月收回并汇总。根据各家医院提供的资料,对我国经导管消融治疗房颤病例资料进行回顾性分析。结果本次调查共收到40家医院自1998年以来共3 196例注册登记资料,其中男性2 193例,女性1 003例,平均年龄(54．77±5．98)岁。阵发性房颤占85．67％,持续性房颤占11．51％,永久性房颤占2．82％。45．93％的患者合并1种或1种以上的基础心脏疾病,伴左心房血栓的患者占0．9％。左心房直径(37．02±3．98)mm,左心室舒张末内径(46．81±4．05)mm,左心室射血分数0．59±0．06。经导管消融治疗房颤的术式主要有5种: (1)局灶消融术;(2)肺静脉节段性消融术;(3)环肺静脉消融术;(4)左心房基质改良术;(5)肺静脉前庭改良术。消融能源中,射频占95．96％,超声占3．00％,冷冻占1．22％。5种术式的终点不尽相同,各术式亦无统一终点。影响成功率和复发率的因素有:性别、年龄、基础疾病、心脏结构与功能、术者经验、房颤类型、房颤病程、消融术式、消融能源等。术后抗心律失常药物的应用明显减少,但抗凝治疗有所加强。总的并发症发生率为7．48％,严重并发症如心脏压塞和肺静脉狭窄3．19％。结论建议在相关条件较好的医院,可将经导管消融作为无基础心脏疾病的阵发性房颤的一线治疗方法。     

Gender-related differences in catheter ablation of atrial fibrillation.

AIMS: Women have an increased risk for atrial fibrillation (AF)-related complications and there is evidence towards a reduced efficacy of the rhythm control strategy than men. A catheter-based strategy is therefore widely attractive, but the impact of gender on catheter ablation (CA) of AF remains undefined. METHODS AND RESULTS: We included 221 consecutive patients (150 men) who underwent CA of drug-refractory AF. Gender differences in clinical presentation and outcomes were compared. Women were older (P = 0.002), had a longer history of AF (P = 0.04), and were more likely to have hypertension (P = 0.04). Moreover, a concomitant valvular heart disease tended to be more common in women (32.4 vs. 23.3%; P = 0.28) and left atrium dimensions were significantly larger (P = 0.003). However, acute success rate and complications rate were similar between genders. After 22.5 +/- 11.8 months of follow-up, the overall freedom from arrhythmia recurrences was similar (83.1 vs. 82.7% in men), and a similar improvement in SF-36 quality of life scores was achieved in both groups. CONCLUSION: Women are referred for AF ablation later with a more complex clinical pre-operative presentation. Despite this higher risk profile in women, no differences were detected in clinical outcomes. Our findings indicate that CA of AF appears to be safe and effective in women as in men.     

长期持续性心房颤动导管消融策略的临床研究

目的：比较导管消融治疗长期持续性心房颤动（房颤）不同消融策略的临床疗效。方法2009年5月至2011年3月,入选240例于上海市胸科医院房颤诊治中心接受三维标测系统（ Carto）指导下的导管消融治疗的长期持续性房颤患者,男138例,女102例。随机分为3组,A组：80例患者行环肺静脉前庭电隔离（ CPVA）及心房碎裂电位（ CFAE）消融,B组：80例患者行CPVA＋CFAE＋左心房线性消融,C组：80例患者行CPVA＋CFAE＋左心房线性消融＋三尖瓣峡部线性消融,消融后未能转复窦性心律患者均行直流电复律。消融术后随访心电图和24 h动态心电图评价疗效,比较3组的安全性及临床效果。结果所有患者均顺利完成导管消融术,平均随访（36±7）个月,单次消融后成功率 A 组37．5%、B组52．5%、C组55．0%,多次消融后成功率A组60．0%、B组75．0%、C组76．3%（ P〈0．05）。各组间并发症发生率差异无统计学意义。结论对于长期持续性房颤患者,在CPVA＋CFAE的基础上行左心房线性消融有助于提高成功率,而三尖瓣峡部线性消融效果不确切。     

Stepwise linear approach to catheter ablation of atrial fibrillation

BACKGROUND: This study attempted to convert atrial fibrillation (AF) to sinus rhythm using a stepwise linear catheter ablation approach. METHODS: One hundred and ninety-six patients (43 with persistent AF) were enrolled in the study. A multiple electrode array was used for anatomical navigation and activation mapping. Continuously incremental stimulation was used to induce AF if spontaneous AF was not present. Stepwise linear ablation was applied until AF was converted to sinus rhythm or atypical atrial flutter (AAFL) or atrial tachycardia (AT). The stepwise approach initially utilized a figure-7 lesion line between the right and left superior pulmonary vein on the roof of the left atrium and then extended along the ridge between the left appendage and the left pulmonary veins until the mitral valve annulus, as the primary lesions. If AF still persisted, high-frequency potentials in the inferior left atrium, coronary sinus, or right atrium were targeted. Noninducibility of AF was used as the end point. RESULTS: AF was converted to sinus rhythm in 81.6% of patients (90.8% of paroxysmal and 51.1% of persistent AF, P<.01). The remainders of patients were converted to AAFL or AT. AF was terminated after ablation in right atrium in 7 patients. During an 18.2+/-7.3 month follow-up, 88.3% of patients were free of atrial tachyarrhythmias without medication, 9.7% of patients had refractory AAFL/AT, and only 2.1% of patients had paroxysmal AF. CONCLUSION: Stepwise linear ablation is effective in converting AF to sinus rhythm and the figure-7 lesion line should be the basic lesion. Right atrium ablation is necessary in some patients.     

持续性心房颤动递进式消融术后复发双环折返性房性心动过速的电生理诊断

目的 阐明递进式消融术治疗持续性心房颤动(房颤)术后复发双环折返性房性心动过速(房速)的电生理特点.方法 入选2007年7月至2012年12月持续性房颤递进式消融术后复发房速的19例患者.结果 19例患者均通过详细的三维激动标测(＞200个采集点)和在每个折返环内拖带的方法确定了双环折返的机制,其中大折返环和大折返环组成的双环折返13例,大折返环和局部小折返环组成的双环折返6例.大多数病例消融策略采取分别消融两折返环各自的峡部,先将双环折返变为单环折返(由再次拖带结果确定),最后消融单折返环峡部终止房速.结论 双环折返性房速并非是持续性房颤递进式消融术后少见的一种心律失常,详细的三维激动标测联合拖带标测是确诊的最佳方案.     

经导管线性消融术对左心房功能影响的研究

目的评价左心房线性消融术对心房颤动（房颤）患者左心房功能的影响。方法选择30例Carto系统标测指导下行左心房线性消融术的阵发性房颤患者，应用超声心动图测定其消融术前1～3d、术后3个月静息时窦性心律下左心房容积指标、二尖瓣口A波速度峰值（VA）及左心房射血力，分析消融术前后左心房功能的变化。结果消融术后反应左心房辅泵功能的指标左心房射血力、VA、左心房主动排空容积、左心房主动排空分数、左心房总排空分数显著下降，反应左心房管道功能的左心房管道容积增加，反应左心房储存功能的指标左心房总排空容积、左心房最大容积无明显变化。结论Carto系统标测下左心房线性消融术后左心房辅泵功能下降，管道功能增强，而储存功能无显著改变。     

阵发性房颤射频消融术后空白期内房性心律失常与房颤远期复发的关系

目的 探讨阵发性房颤射频消融术后3个月（“空白期”）内房性心律失常的发作趋势与远期复发的关系.方法 入选在我院接受首次环肺静脉电隔离射频消融术的阵发性房颤患者50例,并于术后3个月内每月行24h动态心电图检查,同时进行术后定期临床随访和监测12个月.根据术后第12个月体表心电图、24h动态心电图监测及临床随访结果,分为房颤复发组和无复发组,比较复发组患者与无复发组患者术后3个月内房性心律失常发生率及随着时间推移两组房性心律失常的发作趋势.结果 术后第12个月体表心电图及24h动态心电图统计结果显示,房颤复发率为36.0％（18/50）,所有心电图中出现快速型房性心律失常心电图为26.9％,其中房颤20.2％、房扑2.0％、房速4.7％;房性早搏20.1％;窦性心动过缓2.0％.复发组患者术后3个月内房性心律失常的发生率高于无复发组（41.1％比10.2％,P＜0.05）,复发组患者术后3个月内房性心律失常的发生率维持在较高水平（术后3个月分别为44.4％、41.8％、38.5％,P＞0.05）.无复发组患者术后3个月可出现房颤复发,随着时间推移房性心律失常的发生率呈降低趋势（术后3个月分别为18.7％、10.5％、4.4％,P＜0.01）.结论 早期复发不能代表消融失败和晚期复发,但早期房性心律失常发作频繁,则晚期房颤复发的危险性增加.     

房颤射频导管消融术后心功能与左房内径的变化(英文)

目的:观察射频导管消融术(RFCA)治疗心房纤颤(房颤)的疗效及术后心功能和左房内径的变化。方法:回顾分析本院28例有明显临床症状且药物治疗无效,接受RFC治疗的房颤患者的资料。在三维电解剖标测(EAM)系统指导下对该28例房颤患者行射频消融术。术前,术后3、6月用心脏超声仪评价心功能及左房内径的变化;行动态血压监测评价RFCA的疗效;结果:所有患者的肺静脉隔离率为100%。术中术后均未出现严重并发症。随访6个月28例患者中有27例(96.4%)未复发房颤,与术前比较,心脏超声检查示左房内径[(37.3±4.8)mm比(34.1±4.6)mm]明显降低,左室射血分数[(59.8±8.7)%比(64.2±6.8)%]明显提高,P均<0.05。结论:射频导管消融术治疗房颤安全有效,心功能和左房内径均有明显改善。     

慢性心房颤动导管消融:碎裂电位消融和线性消融的比较

目的评价环肺静脉隔离(CPVI)基础上采用心房碎裂电位(CFAEs)消融或(和)线性(Linear)消融进行心房基质改良的疗效。方法回顾性分析156例慢性心房颤动(简称房颤)消融病例,房颤病程2.5±2.3年,左房内径42.4±4.5 mm。根据消融术式改进分为三组CPVI+CFAEs、CPVI+linear和CPVI+CFAEs+Linear组。比较消融术中房颤终止比例及随访疗效。结果三组消融总时间有显著性差异(160±14 min vs 178±9 min vs 241±8min,P<0.01)。CPVI+CFAEs组终止房颤/转变房性心动过速(简称房速)的比例(52.7%)显著高于CPVI+Line-ar组(18.4%),但低于CPVI+CFAEs+Linear组(73.1%)。术后3.1±1.2个月,三组二次消融比例47.3%、51%、38.5%,P=0.43。术后平均随访9.5±1.8个月,三组无房性快速性心律失常复发例数分别为39例(70.9%)、33例(67.3%)和41例(78.8%),P=0.41(服用抗心律失常药物比例25.6%、24.2%和22%,P=0.96)。结论 CP-VI基础上CFAEs消融的房颤终止比例高于单纯线性消融,但低于联合应用CFAEs消融和Linear消融。尽管如此,三组术后二次消融比例和随访成功率无显著性差异。     

右房房性心动过速电生理学特征及射频消融结果

目的 探讨右房房性心动过速(房速)的电生理学特征、靶点标测和射频消融治疗结果。方法 40例右房房速病人行心内电生理检查和射频消融,房速靶点标测采用激动标测方法,用两根大头消融导管在右房内交替移动标测寻找靶点,采用预设60～65℃温控放电消融。结果 经电生理检查证实40例房速中10例为自律性房速,30例为非自律房速。36例(90％)射频消融即刻成功,36例有39个房速病灶位,其分布:房间隔21个,右房侧壁15个,希氏束旁(Koch三角尖)2个。4例合并房室结折返性心动过速改良房室结成功,3例合并心房扑动划线消融成功。有1例希氏束旁房速术后出现Ⅲ°AVB。结论 右房房速射频消融成功率较高,其病灶部位以房间隔或右房侧壁为多见,希氏束旁房速消融应注意防止出现AVB并发症。     

左心房容积指数与心房颤动导管消融预后的关系

目的探讨左心房大小与心房颤动(房颤)导管消融术预后的相关性及其评估指标。方法本中心2005年5月至2006年11月行房颤导管消融的连续43例患者,平均年龄60±12岁,男25例(58%);持续房颤5例(12%);CARTO三维标测下行环肺静脉左心房线性消融。二维超声双平面Simpson法测量左心房前后径(LAD)、上下径和左右径及左心室射血分数(LVEF),椭圆公式(Pum-bo法)计算左心房容积(LAV),体表面积(BSA)标化计算左心房容积指数(LAVI)和左心房内径指数(LADI)。消融后3个月评价疗效,单因素和多因素分析年龄、性别、房颤病史、高血压、LAD、LAV、LADI、LAVI、LVEF与房颤导管消融后复发的关系。结果单次消融3个月后15例(34%)患者有复发。复发组与消融治疗有效组LAVI差异有统计学意义(68.19±23.68mL/m2和52.07±17.34mL/m2,P=0.019),复发组LAVI95%CI54.70～80.30mL/m2。而年龄(59.5±12.0岁和60.5±12.0岁,P=0.806)、性别(男/女分别为7/9和18/9,P=0.338)、房颤病史(4.4±4.2年和5.8±5.3年,P=0.46)、高血压患病率(6/15和11/27,P=0.963)、LAD(4.01±0.50cm和3.87±0.50cm,P=0.41)、LADI(0.0476±0.0018和0.0423±0.0020,P=0.093)、LAV(53.92±17.14mL和49.92±16.65mL,P=0.471)、LVEF(69.7%±10.1%和70.2%±11.0%,P=0.91)差异均无统计学意义。Logistic回归分析LAVI与复发的Pearson相关系数r=0.374呈正相关,OR=1.04,95%CI0.99～1.09,P=0.04。结论LAVI评估左心房的大小优于左心房内径、LADI和LAV等参数;LAVI与房颤导管消融术后成功率相关,可预测房颤导管消融术的预后。我们的研究提示,LAVI≥55mL/m2可作为判断房颤导管消融术后复发高危的参考指标。     

中国经导管消融治疗心房颤动注册研究-2007

目的 分析2007年我国经导管消融治疗心房颤动(房颤)工作的现状.方法 根据各家医院提供的资料,对2007年我国导管消融治疗房颤病例资料进行回顾性分析.结果 截至2008年9月5日,调查共收到40家医院提供的注册登记病例资料2620份,其中男性1719例,女性901例,平均年龄(58.5±11.2)岁.阵发性房颤77.4%,持续性房颤15.7%,长期持续性房颤6.9%.54.1%的患者合并1种或1种以上的基础心脏疾病.左心房内径(38.3±6.3)mm,左心室舒张末期内径(47.8±5.2)mm,左心室射血分数0.63±0.08.经导管消融治疗房颤的主要术式是环肺静脉消融术和环肺静脉消融加必要心房辅助线.消融能源主要为射频,占99.8%.2007年的消融成功率为80.3%,复发率为19.7%.对成功率和复发率有显著影响的因素有左心房内径、房颤类型和消融术式.术后抗心律失常药物的应用有所增多,抗凝治疗明显加强.总的并发症发生率为1.7%,无严重并发症如心房食管瘘和肺静脉狭窄发生.结论 建议在相关条件较好的医院,可将经导管消融作为症状明显的阵发性房颤的一线治疗方法. 舒张末期内径(47.8±5.2)mm,左心室射血分数0 63±0.08.经导管消融治疗房颤的主要术式是环肺静脉消融术和环肺静脉消融加必要心房辅助线.消融能源主要为射频,占99.8%.2007年的消融成功率为80.3%,复发率为19.7%.对成功率和复发率有显著影响的因素有左心房内径、房颤类型和消融术式.术后抗心律失常药物的应用有所增多,抗凝治疗明显加强.总的并发症发生率为1.7%,无严重并发症如心房食管瘘和肺静脉狭窄发生.结论建议在相关条件较好的医院,可将经导管消融作为症状明显的阵发性房颤的一线治疗方法. 舒张末期内径(47.8±5.2)mm,左心室射血分数0 63±0.08.经导管消融治疗房颤的主要术式是环肺静脉消融术和环肺静脉消融加必要心房辅助线.消融能源主要为射频,占99     

中国经导管消融治疗心房颤动注册研究-2008

目的分析2008年我国经导管消融治疗心房颤动（房颤）工作的状况。方法根据房颤注册研究网上平台获得的资料，对2008年我国经导管消融治疗房颤的病例资料进行回顾性分析。结果截至2010年10月5日，调查共收到53家医院提供的注册登记病例资料2808份，其中男1946例，女862例，平均年龄（57．4±11．4）岁。阵发性房颤占71．5％，持续性房颤占22．8％，持久性房颤占5．7％。47．2％的患者合并1种或1种以上的基础心脏疾病。左心房直径（40．6±11．7）mm，左心室舒张末期内径（48．4±5．4）mm，左心室射血分数0．63±0．08。经导管消融治疗房颤的主要术式是环肺静脉隔离术和环肺静脉隔离加必要心房辅助线，消融能源全部为射频。2008年总的消融术成功率为82．1％，复发率为17．9％，对成功率和复发率有显著影响的因素有左心房直径、房颤类型和消融术式。总的并发症发生率为1．7％，严重并发症如心脏压塞和肺静脉狭窄的发生率为0．74％，无心房食管瘘的发生。结论建议在相关条件较好的医院，可将经导管消融作为无基础心脏疾病的阵发性房颤的一线治疗方法。     

Current status and future catheter ablation strategies in atrial fibrillation

Catheter ablation of atrial fibrillation (AF) is a highly effective therapy to achieve freedom of recurrent arrhythmia and relief from symptomatic AF. Transmural ablation of atrial tissue is crucial for success. Thus steerable sheaths and catheter design with contact measurement as an additional feature have been developed to increase success rates. New 3 dimentional (3D) mapping technologies engage clinical routine to reduce fluoroscopy time and radiation dose for patients and medical staff to a minimum. To unmask dormant pulmonary vein reconduction and to avoid early pulmonary vein reconduction administration of adenosine is useful. Future approaches aim at individualized ablation strategies taking clinical and electrophysiologic characteristics of the individual patient into account.     

Anatomical pitfalls during encircling cryoablation of the left atrium for atrial fibrillation therapy in the pig

We previously published encircling endocardial cryo-isolation of the pulmonary vein (PV) region. This study documented mechanisms of isolation failure using CARTO® mapping. Cryo-isolation used a modified Surgifrost® introduced via a Universal Cardiac Introducer® on the left atrial appendage. Of five pigs, two had incomplete isolation and repeat mapping: Activation was over Bachmann’s bundle (BB) in one and the coronary sinus (CS) in the other. Repeat cryoablation failed to eliminate gaps. Histologically, the BB gap had nonlesioned sub-epicardial fibres and thick fat covering the cryolesioned BB: fat protecting the epicardium from cryoablation. The inferior gap had a large CS, and a thick myocardium bridging the isthmus: myocardial thickness and CS thermal sink preventing transmural cryolesions. CARTO® mapping localized gaps. Although the CS is known to cause failure, its protective mechanism is not well documented. The BB gap is novel. These findings have important clinical implications for isolation of the PV region.