消融法治疗心房颤动的现状及前景

从上世纪80年代Cox率先开展外科迷宫手术治疗心房颤动开始,心房颤动的射频消融从Swartz线性消融模拟迷宫手术,发展到Haissaguerre的方式为代表的局灶性心房颤动点消融、肺静脉口节段性消融以及Pappone的方式为代表的左心房壁环形肺静脉消融。从消融房室交界区阻断房室传导,植入永久性起搏器和房室结改良术,发展到心房壁的线性消融,肺静脉的点状环状消融和环肺静脉左房消融。由于心房颤动的发病机制复杂,左右心房及肺静脉均可成为异位起搏点或折返部位,加之心房和肺静脉的管壁薄,致使标测消融部位,确定消融范围以及消融损伤组织的深浅均不易掌握。现就消融法治疗心房颤动的操作方法以及目前的现状与前景综述如下。     

房性心动过速的导管射频消融术治疗

目的:探讨房性心动过速(房速)行导管射频消融术(RFCA)治疗方法、疗效及其安全性。方法:选择24例经心内电生理检查证实为房速并同意行RFCA治疗患者,常规电生理检查分别在高位右房(HRA)、右室心尖部(RVA)2个部位行S1S1刺激和程控期前收缩刺激,记录房速的诱发和终止方式。靶点标测采用激动标测法,单根消融导管于右房或左房(经房间隔穿刺)内标测寻找最早心房激动或用多极导管作为参考电极,再用大头导管寻找消融靶点。根据消融结果,分析房速的起源部位、消融即时成功率、并发症、复发原因以及X线曝光时间等。结果:24例房速患者中,22例(88%)右房房速,3例(12%)左房房速(1例患者同时存在左、右房2个部位房速)。4例与其他心律失常合并存在,1例房室结折返性心动过速,1例合并房性折返性心动过速,1例合并心房颤动,1例同时合并心房扑动和心房颤动。24例患者均完成射频消融治疗(实际消融25例次),均采用温控消融,按预定消融终点,23例次即时消融成功,即时成功率92%(23/25),平均X线曝光时间(32±6.4)min,消融失败2个病例中,右房房速和左房房速各1例,再次消融成功。未发生房室传导阻滞、心包填塞等严重并发...     

心房颤动环肺静脉隔离术后复发左房房性心动过速的特点及消融治疗

目的探讨心房颤动(简称房颤)环肺静脉隔离术后(CPVI)复发左房房性心动过速(简称房速)再次射频消融中,房速机制的鉴别和消融策略的选择。方法18例房颤经CPVI术后复发房速患者,其中男16例,女2例,年龄61.4±6.5(50～70)岁。在持续稳定的自发/诱发房速时在Carto指导下行激动顺序标测,经电生理检测,明确房速机制并选择相应消融方式:对于局灶性房速,重新阻断原消融径线上裂隙或消融最早激动区;对于折返性房速,明确关键峡部,行线性消融,如果有肺静脉电位亦行对裂隙的消融。结果共有13例肺静脉恢复电活动(72.7%)。局灶性房速6例,折返性房速12例(包括11例左房大折返和1例肺静脉-左房折返)。相应方式消融后房速均转为窦性心律,且肺静脉电位消失。结论房颤CPVI术后复发的左房房速与肺静脉电位的恢复密切相关;与消融线和裂隙形成的折返有关。     

上腔静脉电隔离治疗房性心动过速一例

患者女,58岁。阵发性心慌、胸闷2年。发作时不伴血流动力学障碍。发作时心电图表现为2∶1心房扑动和短阵房性心动过速、心房颤动。心电图独特的P波表现提示心房激动顺序从上至下、从右至左。在上腔静脉口部记录到高频腔静脉电位,其异常电活动频率快而不规则,在上腔静脉口部行节段消融,电隔离上腔静脉与右房达到双相阻滞。结论:上腔静脉电隔离可治疗起源于上腔静脉的房性心动过速。     

Carto系统指导下左房电解剖隔离治疗心房颤动

对 3例阵发性和 2例持续性心房颤动 (简称房颤 )进行左房线性消融。采用Carto标测构建左房三维电解剖图 ,并标识出肺静脉和二尖瓣环 ,在距肺静脉口外 1～ 2cm处进行绕左右肺静脉和左房峡部的环状线性隔离消融 ,后 2例增加一条左房后壁的消融线 ,消融的终点为 :①环状隔离区内的双极电压≤ 0 .1mV ,②跨消融线相邻两点的传导时间延迟 30ms以上。结果 :整个手术时间为 2 2 9± 18min ,X线曝光时间为 2 5± 3min。消融线环绕的左房面积占整个被标测左房面积的 36 %± 3.2 % ,消融线环绕的左房区域内的电压较消融前明显降低 ,绕消融线以外的部分心房组织的电压亦降低。 3例阵发性房颤有 2例在术后 1～ 2天有房颤发作 ,1例持续性房颤于术后 1周转为持续性心房扑动 ,3周时电复律为窦性心律 ,术中和术后随访期内无并发症发生 ,5例在 5 .3± 1.85个月的随访中无有症状的房颤发作。结论 :左房线性电隔离治疗房颤是安全有效的方法。     

消融心房脂肪垫治疗心房颤动的研究现状

近年研究表明,迷走神经过度兴奋与一部分心房颤动的发生密切相关。由于支配心房的迷走神经丛主要分布于心房外膜的脂肪垫中,因此,以心房去迷走神经化为终点的脂肪垫消融成为一项新的心房颤动治疗措施。初步研究的结果显示,该术式治疗心房颤动确实有效,但同时也存在若干弊端。现就消融心房脂肪垫治疗心房颤动的现状作一综述。     

图像融合系统指导下的心房颤动射频导管消融研究

目的 评价图像融合系统指导下构建的左心房三维结构对心房颤动射频导管消融效果的影响.方法 回顾性分析连续接受消融的80例心房颤动患者,其中42例在图像融合系统指导下(A组)、38例单纯在常规电解剖标测系统指导下(B组)行消融.消融策略:左右侧肺静脉环形电隔离→左心房碎裂电位消融→左心房顶部、底部、峡部和右房三尖瓣峡部、上腔静脉、冠状窦口部消融.结果 A组平均随访21.2±3.6月,36例(85%)3月后生活质量明显改善,无心房颤动复发,其中3例扩张型心肌病和1例肥厚型心肌病消融成功,术后心功能明显改善.B组平均随访22.1±3.3月,27例(71%)3月后生活质量明显改善,无心房颤动复发;另2例在再次消融后痊愈.结论 图像融合系统能提高心房颤动消融的手术成功率.     

食管造影及温度监测指导环肺静脉消融治疗心房颤动

目的心房-食管瘘是环肺静脉消融的少见并发症,但是伴有极高的病死率。最安全有效的预防心房．食管瘘发生的方法应当是避免消融食管左心房段。我们观察了采用食管造影检测食管和左心房的毗邻关系以及采用食管温度监测下消融左心房毗邻食管段对肺静脉隔离的作用。方法64例阵发性心房颤动（房颤）患者行环肺静脉消融术。行左心房和食管联合造影。在心房注射造影剂的同时,经食管吞人造影剂,观察食管走形和左心房后壁的关系。根据食管心房后壁段和肺静脉前庭的关系将食管走形分为Ⅰ型、Ⅱ型和Ⅲ型。经鼻送入食管温度计于食管左心房后壁相应部位。无食管走形重叠侧肺静脉,常规消融。分三步消融食管走形重叠侧肺静脉。并采用食管温度控制法消融,食管温度达到39℃即中断消融,待恢复正常后再行消融,直至达到肺静脉隔离。结果64例患者中Ⅰ型48例,Ⅱ型11例,Ⅲ型5例。在完成三步消融后,所有患者均完成肺静脉隔离。所有患者中仅有18．8％患者需在邻近食管左心房后壁处消融。结论多数阵发性房颤患者食管和心房后壁仅在一个肺静脉开口相邻,且多数患者可通过不消融食管相邻心房后壁而达到完全肺静脉隔离,可以大大减少消融时食管的损伤。     

心房分离的电生理特征及射频消融治疗

目的 报告一例罕见的心房分离，探讨其发生原因有助于加深对心房扑动(房扑)、心房颤动(房颤)发生机制的认识。方法 心内电生理检查，常规导管放置，测定各部位不应期，诱发房扑、房颤．并对其进行标测，用经典方法消融房扑。结果 本例心房分离表现为右房房颤、左房房扑，心室受右房房颤所控制。射频消融后，房扑不能诱发，同时心房分离现象亦消失。结论 心房分离可能由心房之间不应期不同所致，左右心房自我保护性阻滞使各自节律得以维持。对于房扑始动的心房分离，可经射频消融成功。     

左房低电压与心房颤动相关性的研究进展

心肌纤维化与心房颤动(房颤)可相互影响,互为因果,电解剖标测系统显示的左房低电压提示左房纤维化.近年来大量研究表明左房低电压可显著增加房颤术后的复发风险.研究显示在阵发性房颤患者中,肺静脉隔离附加左房低电压区消融是否更有效存在争议;在持续性房颤患者中,肺静脉隔离附加左房低电压区消融可显著降低房颤的复发风险.此外,左房低...     

Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the "true anatomy" on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation.

BACKGROUND: Current concepts of catheter ablation for atrial fibrillation (AF) commonly use three-dimensional (3D) reconstructions of the left atrium (LA) for orientation, catheter navigation, and ablation line placement. OBJECTIVES: The purpose of this study was to compare the 3D electroanatomic reconstruction (Carto) of the LA, pulmonary veins (PVs), and esophagus with the true anatomy displayed on multislice computed tomography (CT). METHODS: In this prospective study, 100 patients undergoing AF catheter ablation underwent contrast-enhanced spiral CT scan with barium swallow and subsequent multiplanar and 3D reconstructions. Using Carto, circumferential plus linear LA lesions were placed. The esophagus was tagged and integrated into the Carto map. RESULTS: Compared with the true anatomy on CT, the electroanatomic reconstruction accurately displayed the true distance between the lower PVs; the distances between left upper PV, left lower PV, right lower PV, and center of the esophagus; the longitudinal diameter of the encircling line around the funnel of the left PVs; and the length of the mitral isthmus line. Only the distances between the upper PVs, the distance between the right upper PV and esophagus, and the diameter of the right encircling line were significantly shorter on the electroanatomic reconstructions. Furthermore, electroanatomic tagging of the esophagus reliably visualized the true anatomic relationship to the LA. On multiple tagging and repeated CT scans, the LA and esophagus showed a stable anatomic relationship, without relevant sideward shifting of the esophagus. CONCLUSION: Electroanatomic reconstruction can display with high accuracy the true 3D anatomy of the LA and PVs in most of the regions of interest for AF catheter ablation. In addition, Carto was able to visualize the true anatomic relationship between the esophagus and LA. Both structures showed a stable anatomic relationship on Carto and CT without relevant sideward shifting of the esophagus.     

Topographic variability of the esophageal left atrial relation influencing ablation lines in patients with atrial fibrillation

Topography of the esophagus in atrial fibrillation ablation. INTRODUCTION: The close anatomic relationship of the posterior wall of the left atrium (LA) and the thermosensitive esophagus creates a potential hazard in catheter ablation procedures. METHODS AND RESULTS: In 30 patients (pts) with atrial fibrillation (AF) undergoing catheter ablation, we prospectively studied the course and contact of the esophagus in relation to LA and the topographic proximity to ablation lines encircling the right-sided and left-sided pulmonary veins (PV) as well as to the posterior line connecting the encircling lines using the electromagnetic mapping system for reconstruction of LA and for tagging of the esophagus. This new technique of anatomic tagging of the esophagus was validated against the CT scan as a standard imaging procedure. The esophageal course was highly variable, extending from courses in direct vicinity to the left- or right-sided PV as well as in the midportion of the posterior LA. In order to avoid energy application in direct proximity to the esophagus, adjustments of the left and right PV encircling lines were necessary in 14/30 pts (47%) and 3/30 (10%). In 30 pts (100%), the mid- to inferior areas of the posterior LA revealed contact with the esophagus. Therefore, posterior and inferior linear ablation lines were abandoned and shifted to superior in 29 pts (97%). CONCLUSIONS: Anatomic tagging of esophagus revealed a highly variable proximity to different areas of the posterior LA suggesting individual adjustment of encircling and linear ablation lines in AF ablation procedures to avoid the life threatening complication of esophagus perforation.     

Initial experience in the use of integrated electroanatomic mapping with three-dimensional MR/CT images to guide catheter ablation of atrial fibrillation

INTRODUCTION: No prior studies have reported the use of integrated electroanatomic mapping with preacquired magnetic resonance/computed tomographic (MR/CT) images to guide catheter ablation of atrial fibrillation (AF) in a series of patients. METHODS AND RESULTS: Sixteen consecutive patients with drug-refractory AF underwent catheter ablation under the guidance of a three-dimensional (3D) electroanatomic mapping system (Carto, Biosense Webster, Inc., Diamond Bar, CA, USA). Gadolinium-enhanced MR (n = 8) or contrast-enhanced high-resolution CT (n = 8) imaging was performed within 1 day prior to the ablation procedures. Using a novel software package (CartoMerge, Biosense Webster, Inc.), the left atrium (LA) with pulmonary veins (PVs) was segmented and extracted for image registration. The segmented 3D MR/CT LA reconstruction was accurately registered to the real-time mapping space with a combination of landmark registration and surface registration. The registered 3D MR/CT LA reconstruction was successfully used to guide deployment of RF applications encircling the PVs. Upon completion of the circumferential lesions around the PVs, 32% of the PVs were electrically isolated. Guided by a circular mapping catheter, the remaining PVs were disconnected from the LA using a segmental approach. The distance between the surface of the registered 3D MR/CT LA reconstruction and multiple electroanatomic map points was 3.05 +/- 0.41 mm. No complications were observed. CONCLUSIONS: Three-dimensional MR/CT images can be successfully extracted and registered to anatomically guided clinical AF ablations. The display of detailed and accurate anatomic information during the procedure enables tailored RF ablation to individual PV and LA anatomy.     

电解剖标测和磁共振影像融合技术指导导管消融心房颤动的有效性研究

目的探讨三维电解剖标测（CARTO）系统重建图像和预先取得的磁共振影像融合后指导心房颤动（房颤）导管消融的有效性。方法从2005年9月至2006年9月对连续100例药物治疗无效的房颤患者行导管消融治疗,基本策略均为在CARTO系统指导下进行环肺静脉线性消融并实现电学隔离。随机分为2组,每组50例。第1组为术前配准组,在消融开始前即进行影像配准并融合,并在此融合影像指导下进行导管消融,消融结束后进行再次融合;第2组为术后配准组,在单纯CARTO技术指导下消融,消融结束后才进行影像配准并融合。最后比较两组的消融结果并评估消融过程中的差异。结果环肺静脉消融结束后,第1组左心房三维磁共振表面重建影像至电解剖标测图像各点平均距离为（1．6±0．7）mm,消融线上平均标记位点（75±27）个,平均X线透视时间（31±21）min;第2组的上述指标分别为（2．1±1．3）mm、（98±38）个、（55±29）min。以上组间比较差异都有统计学意义。将实际消融线与预定消融线比较,第2组中有组间差异的偏差区域分别是左侧肺静脉前庭顶部（15例）、底部（11例）、前下缘（23例）、前上缘（24例）和右侧肺静脉前庭后上缘（12例）、底部（10例）、前下缘（15例）。结论影像融合技术指导导管消融可提高准确性,并可减少X线透视时间及消融点数。     

Three-dimensional esophagus reconstruction and monitoring during ablation of atrial fibrillation: Combination of two imaging techniques

Objective

The purpose of the study was to determine the accuracy of a novel three-dimensional (3D) imaging integration technique of the esophagus combining multislice computed tomography (CT) scan of the esophagus into the three-dimensional (3D) electroanatomic map just before pulmonary vein (PV) isolation.

Methods

We included 94 consecutive patients with symptomatic atrial fibrillation (AF) who underwent ablation. All patients had a CT performed prior procedure that was integrated to the 3D reconstruction electromechanical map of the atrium and the esophagus (Verismo^TM, EnSite® NavX version 7.0J, St. Jude Medical Inc.). During the procedure, a quadripolar electrophysiology catheter placed in the esophagus was used for mapping and to monitor esophagus position. Integrated (fusion) images were used to determinate the esophagus position compared to the left atrium posterior wall and its relationship with PV ostiums. We compared esophagus position by CT and fusion images.

Results

Procedural success was 97.9% with no fatal complications. Esophagus locations were as follows: left 57%, right 7%, oblique course 11% and central 25%. Agreements in esophageal position between CT and fusion imaging techniques were 83.3% and 64% for patients with a recent (≤ 48 h) and non-recent CT assessment (> 48 h), respectively. Throughout the procedure, esophagus stability was 88.8% (lateral displacement < 15 mm). Ablative strategy was modified in 51% of the cases due to awareness of esophagus location.

Conclusion

Guidance of AF ablation with 3D fusion images was safe and effective. CT images of the esophagus, especially if acquired within 48 h before ablation, ensure appropriate intraprocedural localization of the esophagus.     

Three-dimensional rotational angiography of the left atrium and esophagus—A virtual computed tomography scan in the electrophysiology lab?

BACKGROUND: Three-dimensional (3D) reconstruction of the heart and surrounding structures has been supplementing traditional two-dimensional imaging to guide diagnostic and therapeutic electrophysiologic procedures. Current methods using computed tomography (CT)/magnetic resonance imaging (MRI) reconstruction have certain limitations. OBJECTIVE: We investigated the feasibility of rotational angiography (RA) combined with simultaneous esophagogram to create an intraprocedural 3D reconstruction of the left atrium (LA) and the esophagus. METHODS: Rotational angiography was performed. Contrast was injected via a pigtail catheter positioned in the left or right pulmonary artery to achieve a levophase venous cycle opacification of the ipsilateral pulmonary veins and adjacent LA. Simultaneous administration of oral contrast allowed a 3D reconstruction of the esophagus in the same image. Qualitative and quantitative comparison between the intraprocedural 3D RA and a remote CT scan was performed in 11 consecutive patients undergoing ablation for atrial fibrillation. RESULTS: Adequate visualization of the pulmonary veins, adjacent posterior LA, and esophagus was achieved in 10 patients. Determination of pulmonary transit time to guide the initiation of RA resulted in better-quality imaging. A close correlation between 3D RA and CT was found. Based on close proximity between the LA and esophagus, the ablation procedure was modified in three patients. CONCLUSIONS: Three-dimensional RA of the LA and esophagus is a promising new method allowing intraprocedural 3D reconstruction of these structures comparable in quality to a CT scan. Further studies refining the method are justified because it could eliminate the need for CT/MRI scans before ablation.     

Temporal stability of the location of the esophagus in patients undergoing a repeat left atrial ablation procedure for atrial fibrillation or flutter

Background: The esophagus may be mobile during a left atrial (LA) ablation procedure for atrial fibrillation (AF).
Objective: The goal of the study was to determine whether the location of the esophagus is stable in patients undergoing a repeat LA ablation procedure.
Methods: Forty-two patients underwent repeat LA ablation a mean of 7 ± 2 months after the initial procedure. Cinefluoroscopic images of the esophagus during a barium swallow were recorded and the course of the esophagus was tagged on the 3D map. The position of the esophagus at the index and repeat procedure were compared.
Results: At the index procedure, the esophagus was located near the left pulmonary veins (PVs) in 20 (48%), right PVs in 13 (31%), and at the mid LA in 9 (21%) patients. During the repeat procedure, the esophagus was found to be near the left PVs in 22 (52%), right PVs in 11 (26%), and at the mid LA in 9 patients (21%). In 35 of the 42 patients (83%), there was no change in the esophageal location, and in the remaining seven patients (17%), its position had shifted by ≥1 cm (range 1.0–4.0 cm).
Conclusions: In more than 80% of patients presenting for a repeat LA ablation procedure, the esophagus is in the same position relative to the PVs as during the initial procedure. Therefore, if radiofrequency ablation at a particular location was limited by the position of the esophagus, safe ablation at that site is unlikely to be feasible during a repeat procedure.     

左心房及肺静脉同步食管CT血管成像在心房颤动射频消融术中的辅助作用

目的:心房-食管瘘是心房颤动介入及心脏外科手术射频消融治疗中少见但严重的并发症,伴有极高的病死率。最安全有效的预防心房-食管瘘发生的方法,应当是术前了解左心房、肺静脉及周围脏器解剖关系,预防消融烧伤食管心房段。我们进行了术前64层螺旋CT(64层MSCT)左心房及肺静脉成像同时引入食管造影检测食管和左心房的毗邻关系。方法:232例左心房及肺静脉成像(心房颤动组146例,对照组86例),同步进行食管联合造影,即注射造影剂的同时食管吞入造影剂,以观察食管走形和左心房的关系。根据食管心房后壁段与上下PV的关系将食管走形分为:I、II型,其中各型又分别分为abc三种亚型。融合影像的同时,在CARTO系统上显示LA-PV及ESO的三维重建关系,以指导完成肺静脉隔离。结果:228例患者中,I型-Ia39例(心房颤动组24例、对照组15例),占17.11%,Ib55例(心房颤动组39例、对照组16例),占24.12%,Ic 76例(心房颤动组48例、对照组28例),占33.33%;II型-IIa27例(心房颤动组16例、对照组11例),占11.84%,IIb18例(心房颤动组10例、对照组8例),占7.89%,IIc13例(心房颤动组7例、对照组6例),占5.70%。食管跨左心房后壁段长度平均为(55.04±9.01)mm[心房颤动组(54.77±9.49)mm、对照组(55.51±8.14)mm],食道厚度约为(2.26±0.64)mm[心房颤动组(2.25±0.63)mm、对照组(2.30±0.65)mm],左心房后壁厚度中位数房颤组0.6mm(0.3mm,2.9mm)、对照组1.4mm(0.3mm,2.9mm)。食道前壁距左心房最小距离中位数房颤组1.75mm(0mm,5mm)、对照组2.15mm(0mm,4.4mm)。所有心房颤动组患者均完成了肺静脉隔离。结论:本中心完成一组大样本量国人食道左心房肺静脉CT成像,提出6种分型,但心房颤动组和对照组数据在长度、厚度、距离和分型上无明显差异。利用融合影像学技术在射频消融术中指导解剖位置,提高手术安全性。     

多层螺旋CT和Ensite3000标测系统测量左心房食管间距离的相关性研究

目的:探讨多层螺旋CT下和Ensite3000标测系统下左心房食管间距离的相关性.方法:选择20例阵发性心房颤动患者,分别于导管射频消融前行多层螺旋CT测量左心房食管间距离及于消融术中在Ensite3000标测系统下测量左心房食管间距离,并比较其相关性.结果:多层螺旋CT测量的左心房食管间最短距离为(3.5±0.8)mm,三维标测系统测量的左心房食管间最短距离为(3.2±1.1)mm,Pearson相关分析表明,2种方法测量下的左心房食管间最短距离呈正相关(r=0.8,P<0.05).结论:Ensite3000标测系统下测量左心房食管间距离可行,间接说明远离左心房后壁或避开与食管紧靠的左心房后壁的心房颤动导管射频消融策略在临床上可行.     

Relationship of the esophagus and aorta to the left atrium and pulmonary veins: Implications for catheter ablation of atrial fibrillation

BACKGROUND: A potential complication during ablation of atrial fibrillation (AF) is damage to adjacent structures such as the esophagus and aorta. Fatal atrio-esophageal fistulas have developed after surgery- or catheter-based AF ablation procedures. OBJECTIVES: The purpose of this study was to analyze multidetector computed tomography (MDCT) angiographic images to determine the anatomic relationship of the aorta and esophagus to the left atrium (LA). METHODS: Sixty-five subjects underwent CT imaging using a 16-slice MDCT scanner: 24 with paroxysmal AF, 21 with chronic AF, and 20 "control" subjects without a history of AF. Measurements assessed included LA diameters, width of the esophagus and aorta in contact with the posterior LA wall, and distance from the esophagus to the four pulmonary veins (PVs), spine, and LA endocardium. RESULTS: Mean LA diameters were significantly larger in patients with AF vs the control group (P = .003 for anteroposterior diameter; P = .009 for transverse diameter). The anterior aspect of the esophagus was directly apposed to the LA in all cases (contact width 18.9 +/- 4.4 mm). The position of the esophagus varied in the posterior mediastinum but on average was closer to the ostia of the left PVs (P = .0001). The descending aorta was in contact with the LA and/or left PVs in 50 of 65 subjects. The esophagus was closer to the spine in the chronic AF vs control group (P = .007), likely due to increased LA dimension. CONCLUSION: In addition to its ability to assess PV anatomy, preprocedural MDCT imaging can investigate the variable relationship of adjacent structures, such as the esophagus and aorta to the LA and PVs.