Heart Rhythm
Volume 7, Issue 1 , Pages 81-87, January 2010

Intrapericardial balloon placement for prevention of collateral injury during catheter ablation of the left atrium in a porcine model

UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine at UCLA, Los Angeles, California

Received 11 August 2009; accepted 14 September 2009. published online 18 September 2009.

Article Outline

Background

Catheter ablation of the left atrium (LA) is associated with potential collateral injury to surrounding structures, especially the esophagus and the right phrenic nerve (PN).

Objectives

The purpose of this study was to evaluate the efficacy and feasibility of intrapericardial balloon placement (IPBP) for the protection of collateral structures adjacent to the LA.

Methods

Electroanatomic mapping was performed in porcine hearts using a transseptal endocardial approach in eight swine weighing 40–50 kg. An intrapericardial balloon was inflated in the oblique sinus, via percutaneous epicardial access, to displace the esophagus. Similarly, with the balloon positioned in the transverse sinus, IPBP was used to displace the right PN. Esophageal temperature was monitored while endocardial radiofrequency (RF) energy was delivered to the distal inferior PV.

Results

In all cases, balloon placement was successful with no significant effects on hemodynamic function. Balloon inflation increased the distance between the esophagus and posterior LA by 12.3 ± 4.0 mm. IPBP significantly attenuated increases in luminal esophageal temperature during endocardial RF application (6.1 ± 2.4°C vs. 1.2 ± 1.1°C; P<.0001). High-output endocardial pacing from the right superior pulmonary vein ostium stimulated PN activity. After displacement of the right PN with IPBP, PN capture was abolished in 30 (91%) of 33 sites.

Conclusions

These findings demonstrate that in an animal model, IPBP is feasible in the setting of catheter ablation procedures and has the potential to decrease the risk of collateral damage to the esophagus and PN during LA ablation.

Keywords: Catheter ablation, Esophageal injury, Phrenic nerve injury

Abbreviations: AF, atrial fibrillation, CIPV, common inferior pulmonary vein, EA, electroanatomic, ECG, electrocardiogram, IPBP, intrapericardial balloon placement, LA, left atrium, PN, phrenic nerve, PV, pulmonary vein, RF, radiofrequency, RSPV, right superior pulmonary vein, VT, ventricular tachycardia

 

Pulmonary vein (PV) isolation by endocardial catheter ablation is an established treatment for atrial fibrillation (AF).1 Supplemental linear ablations have improved efficacy in some cases, particularly for persistent AF.2, 3 However, a major risk associated with endocardial ablation is collateral damage to tissues near the posterior left atrium (LA), which can have lethal consequences.4 Collateral damage from endocardial ablation may result in atrioesophageal fistula5 or phrenic nerve (PN) injury.6, 7 The risk of collateral damage limits application of radiofrequency (RF) energy in certain areas such as the posterior LA wall and near the right superior PV (RSPV).

Intrapericardial balloon retraction of the LA for prevention of esophageal injury during endocardial catheter ablation was recently reported.8 Balloon inflation9, 10 or infusion of air11 into the pericardial space has also been used for protection of the left PN during epicardial ventricular tachycardia (VT) ablation. Despite these case reports, no systematic assessment of an intrapericardial balloon protection strategy has been performed to demonstrate protection of collateral tissues during LA ablation. The purpose of this study was to assess the efficacy and feasibility of a novel intrapericardial balloon placement (IPBP) technique to displace and protect the esophagus and right PN during LA ablation.

Back to Article Outline

Methods 

This protocol was approved by the UCLA Animal Research Committee and was performed according to institutional guidelines.

Animals and preoperative preparation 

Eight pigs weighing 40–50 kg were anesthetized with 1.4 mg/kg Telazol (intramuscular) and then intubated. Artificial respiration was maintained via endotracheal tube and mechanical ventilator (Summit Medical, Bend, OR). General anesthesia was maintained with inhaled 1.5%–2.5% isoflurane. Femoral venous and arterial catheters were inserted using modified Seldinger technique. Electrocardiogram (ECG) and arterial pressure were monitored continually during procedures. Luminal esophageal temperature was monitored as described elsewhere12, 13, 14 by inserting an esophageal catheter (Blazer II 4-mm-tip catheter, EP Technologies/Boston Scientific, San Jose, CA) orally and advancing to the level of the LA under fluoroscopic guidance. Epicardial access was obtained via subxiphoid puncture using a Tuohy needle as described elsewhere8; an 8-Fr sheath (SL0, St. Jude Medical, Inc., Minnetonka, MN) or an 8.5-Fr deflectable sheath (Agilis, St. Jude Medical, Inc., Minnetonka, MN) was advanced over a guide wire into the pericardial space. After administration of intravenous heparin, a single transseptal puncture was performed to pass an 8-Fr SL0 sheath into the LA. A circular mapping catheter (Optima, St. Jude Medical, Inc., Minnetonka, MN) and a 4 mm steerable electrophysiology catheter were used for mapping the LA and PVs endocardially.

IPBP 

Through the epicardial sheath, Meditech 4 cm balloon catheters (diameter, 12–18 mm; Meditech, Boston Scientific) were advanced over a guide wire to the oblique sinus, immediately adjacent to the posterior LA. When positioned between the LA and esophagus, the balloon was inflated with a contrast agent using an insufflator until complete inflation was observed radiographically. In addition to fluoroscopy, electroanatomic (EA) mapping (NavX system, St. Jude Medical, Inc., Minnetonka, MN) was used to determine LA geometry and analyze movement of the common inferior PV (CIPV) antrum and the esophagus, with three-dimensional geometry created by a quadripolar electrophysiology catheter before and after balloon inflation. The mean arterial pressure and heart rate were continuously monitored for the duration of the procedure.

In porcine hearts, the CIPV is the cardiac structure situated closest to the esophagus. A nonirrigated 4-mm-tip ablation catheter (Celsius, Biosense Webster, Diamond Bar, CA) was positioned endocardially at the distal CIPV to deliver RF energy near the esophagus with and without IPBP. The balloon catheter was positioned in the intrapericardial space between the ablation catheter and the esophagus. To verify reproducibility of the findings, high-power RF energy was delivered from three different positions in the CIPV. Power was limited to 50 W with a maximal tip temperature of 60°C for 30 seconds with each application. The esophageal catheter was positioned against the anterior esophageal wall, directly opposite the ablation catheter in the distal CIPV, and guided by the EA map and fluoroscopic views. After balloon inflation, CIPV and esophageal catheters were repositioned, if necessary, to minimize the distance between them. The temperature probe's position was verified by EA map and fluoroscopy in three planes (left anterior oblique, right anterior oblique, and anterior-posterior) and adjusted frequently to compensate for any movements of the catheter tips. The temperature probe output was time tagged and annotated to the procedure log every 3 seconds before, during, and after RF catheter ablation.

Catheter ablation near the right PVs can cause collateral damage to the right PN, which runs along the pericardium.6, 7 To separate the pericardium and the PN, we positioned the intrapericardial balloon adjacent to the anterior aspect of the RSPV. After creating LA and PV geometry by EA mapping, location of the right PN was identified around the anterior aspect of the RSPV by eliciting diaphragmatic stimulation with bipolar pacing (10 mA, 2 ms pulse width) from the distal pole of the endocardial catheter. These locations were marked on the EA map. After each balloon placement and inflation, endocardial high-output pacing was repeated at these sites to assess for PN capture.

Statistical analysis 

All continuous data are expressed as mean ± standard deviation. The Pearson correlation coefficient was used to quantify the relationship between variables. Changes in esophageal temperature were analyzed initially by repeated measure of analysis of variance (ANOVA), followed by Student's t-test to compare temperatures with and without IPBP. A two-sided P-value of <.05 was considered statistically significant.

Back to Article Outline

Results 

Approaches for positioning the intrapericardial balloon 

Anesthesia was uneventful in all animals, and all procedures were completed as planned. In all animals, intrapericardial balloons were successfully positioned and inflated in the oblique sinus, adjacent to the posterior LA. After subxiphoid puncture and access to the pericardial space, two approaches were used to position the balloon near the CIPV ostial region: direct posterior access and anterior access with deflectable sheath guidance. The Tuohy needle was directed toward the apex of the heart, and advancement of the guide wire indicated whether posterior or anterior access was achieved. Movement of the guide wire to the posterior wall allowed a direct posterior approach, in which the balloon catheter was advanced and positioned behind the posterior LA (Figure 1A). In the event of anterior advancement of the guide wire, catheter guidance from the anterior wall toward the posterior LA was facilitated by use of a deflectable sheath (Figure 1B). Balloon placement within the pericardial space is shown in Figure 1C.

  • View full-size image.
  • Figure 1. 

    Intrapericardial balloon position. Anterior-posterior (AP) and left anterior oblique (LAO) views of the intrapericardial balloon positioned using different approaches: A: Direct puncture to the posterior pericardial space; B: anterior access with deflectable sheath guidance; C: postprocedural, in vivo photographs of inflated intrapericardial balloon (yellow arrow). PN along the pericardium is indicated by dashed white arrow. ESO = esophageal mapping catheter; PV Map = pulmonary vein mapping catheter.

Esophageal displacement 

Figure 2 and Table 1 show typical results of IPBP on LA-esophageal distance. After pericardial balloon inflation, the average distance between the esophagus and atrial endocardium increased by 12.3 ± 4.0 mm, calculated by EA mapping and confirmed fluoroscopically (Table 1). In three animals, simultaneous CIPV and esophageal movement was documented after balloon inflation (Figures 2A–2B). During balloon inflation, mean arterial blood pressures and heart rates did not significantly change (80.4 ± 4.4 vs. 76.4 ± 6.4 mmHg, and 78.5 ± 5.0 vs. 79.8 ± 7.2 bpm, respectively; P = NS). After balloon inflation, changes in mean arterial pressure (−3.8 ± 6.9 vs. −4.3 ± 4.7 mmHg; P = NS) and heart rate (1.4 ± 3.3 vs. 1.0 ± 4.6 bpm; P = NS) were not significantly different between small (12–14 mm) and large (16–18 mm) balloons.

  • View full-size image.
  • Figure 2. 

    Separation of the LA and esophagus during IPBP. A: Modified left lateral view of EA images; B: left anterior oblique (LAO) fluoroscopic view of the LA and contrast-filled esophagus, before and after balloon inflation in the same animal. In this case, balloon inflation caused simultaneous movement of the CIPV and esophagus away from each other. Esophagus and PV map catheter separation increased with balloon inflation. C: Right anterior oblique (RAO) view; D: posterior view of EA maps in the same porcine heart and esophagus shown in Figure 1A. During balloon inflation within the oblique sinus, the esophagus was markedly flattened (D) and shifted away from the posterior LA. The minimum distance between the LA and esophagus increased by 21 mm. ESO = esophagus; RSPV = right superior PV; LSPV = left superior PV; CIPV= common inferior PV; LAA = LA appendage; EPI = epicardial shell. PV map = pulmonary vein mapping catheter located at the CIPV ostium.

Table 1. Separation of esophagus and atrium before and after IPBP
Animal no.ApproachBalloon size, mmMaximum displacement of esophagus, mmMean pressure, mmHgHeart rate, bpm
ControlDuring IPBPControlDuring IPBP
1Anterior, deflectable sheath121086868284
2Posterior puncture121170707576
3Anterior, deflectable sheath121080868892
4Anterior, deflectable sheath14888767874
5Anterior, deflectable sheath141179727882
6Posterior puncture161376778082
7Anterior, deflectable sheath161478727268
8Posterior puncture182180727580
Average ± SD 14.3±2.312.3±4.080.4±4.476.4±6.478.5±5.079.8±7.2

Balloon protection of esophagus during RF energy application 

In six animals, an ablation catheter was positioned in the distal CIPV close to the esophageal catheter, and an intrapericardial balloon was successfully placed (12 mm in three, 14 mm in two, and 16 mm in one animal) between these catheters (Figure 3A). During ablation and recovery, esophageal temperature increased by 6.1 ± 2.4°C under control conditions, significantly more than in the presence of IPBP (1.2 ± 1.1°C, P <.0001; Figure 3B, top). At each time point during ablation and recovery, balloon inflation also significantly attenuated the rise in esophageal temperature (P <.004). Temperature attenuation during IPBP was not significantly different (P = .64) between smaller (12 mm) and larger balloon sizes (14–16 mm). Balloon inflation did not affect mean arterial pressures or heart rates during RF catheter ablation application (Figure 3B, bottom).

  • View full-size image.
  • Figure 3. 

    Luminal esophageal temperature. A: Fluoroscopic images of the positions of each electrode without IPBP (control, upper panel) and with balloon inflation (IPBP, middle panel) in the LAO fluoroscopic views. LAO EA images (lower panel). ESO = esophageal catheter; ABL = endocardial ablation catheter. B: Time courses of luminal esophageal temperature, mean arterial pressure (MAP), and heart rate (HR) during RF catheter ablation (RFCA) at the distal CIPV and during recovery. Temperature increased during control conditions (no IPBP, white circles) but was unchanged with balloon inflation. Overall temperature increased significantly in control conditions compared with in IPBP groups for all balloon sizes (P<.0001, ANOVA). At each time point during RFCA application and over 30 seconds of recovery, control temperatures were significantly greater than IPBP groups (P<.004, Student's t-test). There were no significant differences in the esophageal temperature between the smaller (12 mm, blue circles) and larger balloons (14–16 mm, red circles; P = .64, ANOVA). During RFCA application and recovery phases, MAP and HR did not change significantly.

Displacement of right PN 

Figure 4 and Table 2 show typical results of IPBP protection of the right PN. At a total of 33 total sites (4.1 sites/animal), endocardial high-output pacing around the RSPV anterior ostium resulted in PN capture before IPBP inflation (Table 2). These sites were tagged as PN capture sites. In all animals, positioning of the balloon catheter for protection of the PN was achieved via a superior approach through the transverse sinus or via an inferior approach using a deflectable sheath (Figure 4). Slight anatomic differences between animals dictated which approach (superior or inferior) was appropriate. Balloon inflation prevented PN capture at 30 (91%) of 33 tagged sites (see online movie). All animals had normal PN capture at the end of the study, as confirmed by repeat high-output pacing and fluoroscopy after removal of the intrapericardial balloon, demonstrating that inflation of the intrapericardial balloon did not cause PN injury.

  • View full-size image.
  • Figure 4. 

    PN protection. A, B: left and right anterior oblique, respectively, fluoroscopic images of the same porcine heart shown in Figure 1B. A 16 mm by 4 cm balloon was inflated near the anterior aspect of the RSPV via the transverse sinus (superior approach). A mapping catheter (Map) was positioned at the endocardial RSPV ostium for high-output pacing. Fluoroscopic AP (C) and right lateral EA (D) images of a second porcine heart show a 12 mm by 4 cm balloon inflated near the anterior aspect of the RSPV via an inferior approach. Red circles indicate sites with PN capture before balloon inflation.

Table 2. Displacement of PN
Animal no.Balloon size, mmSites with PN captureSites with PN displacement
Superior approachInferior approach
112555
212444
312434
414333
514530
616332
716444
818534
Total 332826

Note: There was no PN injury after IPBP.

Complications 

There were no cases of hemopericardium, cardiac tamponade, or intrapericardial balloon rupture. No other acute complications were observed.

Back to Article Outline

Discussion 

To our knowledge, this is the first in vivo animal study to systematically examine the feasibility and efficacy of IPBP in the setting of LA ablation. The major findings of this study are as follows: (1) IPBP was technically feasible in this animal model and did not result in acute complications; (2) IPBP effectively displaced vulnerable collateral tissues; and (3) IPBP prevented significant esophageal heating from endocardial RF delivery, as well as PN capture from endocardial pacing.

Esophageal displacement and protection 

Over the past decade, the use of catheter ablation for the treatment of AF has increased.15 In an effort to improve procedural outcomes, extensive LA lesion sets have been proposed.2, 3 Esophageal injury and atrioesophageal fistula are potentially life-threatening complications that may arise from RF energy applied to the posterior LA wall.5 One recent study showed that an esophageal ulcer was observed by endoscopy 1–3 days after AF ablation in 36% of patients without luminal esophageal temperature monitoring.16 Multiple strategies have been proposed to detect esophageal heating and to protect the esophagus during ablation. The esophagus can be filled with radioopaque contrast media to determine its position fluoroscopically and limit RF application adjacent to the esophagus.17 Temperature monitoring within the esophagus has also been used to detect esophageal heating during ablation.12, 16 Active protection techniques have also been proposed, including an esophageal cooling system18 and mechanical displacement of the esophagus away from the LA using an endoscopic transesophageal probe.19, 20

More recently, other strategies aimed at increasing the distance between the heart and collateral structures have been proposed. Methods using intrapericardial air and saline11 or an intrapericardial balloon9 to separate the heart from the PN during ablation have been described. Our group published a case report describing the use of an intrapericardial balloon to protect the esophagus in a patient undergoing repeat AF ablation8; the findings suggested that IPBP may allow safe and effective delivery of RF energy to the targeted tissues. The present study is the first systematic experimental evaluation of such an IPBP technique.

These data demonstrate that the IPBP approach is technically feasible in porcine hearts. Appropriate balloon alignment was achieved using one of two approaches, and balloon position within the pericardial space was stable after balloon inflation. In all animals, the esophagus was displaced from its original position by intrapericardial balloon inflation. In some cases, both the esophagus and the PV were displaced. Nevertheless, no significant hemodynamic consequences resulted from impaired LA filling, and no significant complications were observed. Optimization of size and shape for intrapericardial balloons warrants further study.

The mechanism of esophageal injury or fistula during RF ablation is not completely understood. Thermal injury is the most likely cause (with an area of necrosis surrounded by inflammatory cells), although an ischemic mechanism has also been proposed.5, 21, 22 Shorter distance and increased contact force might increase the risk of esophageal injury.23 The IPBP method has potential advantages for the prevention of esophageal injury during RF application. In addition to displacement of the esophagus, the presence of the intervening liquid-filled balloon likely conferred additional shielding of surrounding tissues from RF energy. For difficult balloon catheter approaches, the deflectable sheath proved valuable for precise positioning in the pericardial space.

Right PN displacement 

The PN has an epicardial course (Figure 1C), and PN injury has been reported after percutaneous catheter ablation procedures for accessory pathways,24 inappropriate sinus tachycardia,25 and AF.6, 7, 26 The anterior wall of the RSPV is less than 2 mm from the right PN in 32% of subjects based on autopsy data.27 The reported prevalence of PN injury as a complication of AF ablation is 0.11%–0.48%.7, 28 Methods to prevent left PN injury during epicardial catheter ablation for VT have been proposed.9, 10, 11 To our knowledge, there have been no reports describing an effective displacement technique of the right PN in the setting of LA ablation. Our experimental observations suggest that two balloon approaches (superior and inferior) with a deflectable sheath appear to be feasible for displacement and protection of the right PN in this animal model. In addition, the balloon catheter was easily repositioned from an esophageal protection site in the oblique sinus, to the anterior aspect of the RSPV for protection of the right PN, suggesting that IPBP provides a flexible approach for collateral protection during LA ablation.

Back to Article Outline

Limitations 

The present study was performed in a limited number of porcine hearts, which have anatomic differences from human hearts. The porcine esophagus is usually positioned slightly further away from the posterior LA than in humans. However, it can be argued that the closer proximity between the esophagus and posterior LA in humans suggests that IPBP may be even more useful in humans than in our animal model. For this technique, epicardial access is required, which is not performed in all ablation centers and carries its own inherent risks. Our studies used an impedance-based EA mapping system. Balloon inflation may have caused a small change in the thoracic impedance field, which could alter the EA map. However, no changes in cardiac geometry (PVs, left appendage, and LA wall) were detected, and catheter position was confirmed by fluoroscopic imaging. Our study did not address the minimum volume or ideal shape of the balloon for attenuating the rise in temperature in the esophagus. Further studies are warranted to elucidate the potential significance of IPBP in a clinical setting and to optimize balloon shapes and sizes.

Back to Article Outline

Conclusions 

Our experimental observations suggest that the IPBP concept is feasible and might decrease the risk of collateral damage that would otherwise occur during RF catheter ablation of the LA. Deflectable sheath guidance may facilitate the optimal positioning of the intrapericardial balloon. If the results in this animal study are borne out in humans, the IPBP method might one day serve as a tool to improve the safety and efficacy of catheter ablation procedures for LA arrhythmias such as AF.

Back to Article Outline

Acknowledgments 

The authors thank Dr. Tara Bourke, Nikhil Sunny Patel, and Kelly A. Walker for their assistance with porcine experiments.

Back to Article Outline

Supplementary data 

Play video

download video

online movie.

Back to Article Outline

References 

  1. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998;339:659–666
  2. Jais P, Hocini M, Hsu LF, et al. Technique and results of linear ablation at the mitral isthmus. Circulation. 2004;110:2996–3002
  3. Hocini M, Jais P, Sanders P, et al. Techniques, evaluation, and consequences of linear block at the left atrial roof in paroxysmal atrial fibrillation: a prospective randomized study. Circulation. 2005;112:3688–3696
  4. Cappato R, Calkins H, Chen SA, et al. Prevalence and causes of fatal outcome in catheter ablation of atrial fibrillation. J Am Coll Cardiol. 2009;53:1798–1803
  5. Cummings JE, Schweikert RA, Saliba WI, et al. Brief communication: atrial-esophageal fistulas after radiofrequency ablation. Ann Intern Med. 2006;144:572–574
  6. Bai R, Patel D, Di Biase L, et al. Phrenic nerve injury after catheter ablation: should we worry about this complication?. J Cardiovasc Electrophysiol. 2006;17:944–948
  7. Sacher F, Monahan KH, Thomas SP, et al. Phrenic nerve injury after atrial fibrillation catheter ablation: characterization and outcome in a multicenter study. J Am Coll Cardiol. 2006;47:2498–2503
  8. Buch E, Nakahara S, Shivkumar K. Intra-pericardial balloon retraction of the left atrium: a novel method to prevent esophageal injury during catheter ablation. Heart Rhythm. 2008;5:1473–1475
  9. Buch E, Vaseghi M, Cesario DA, et al. A novel method for preventing phrenic nerve injury during catheter ablation. Heart Rhythm. 2007;4:95–98
  10. Fan R, Cano O, Ho SY, et al. Characterization of the phrenic nerve course within the epicardial substrate of patients with nonischemic cardiomyopathy and ventricular tachycardia. Heart Rhythm. 2009;6:59–64
  11. Matsuo S, Jais P, Knecht S, et al. Images in cardiovascular medicine (Novel technique to prevent left phrenic nerve injury during epicardial catheter ablation). Circulation. 2008;117:e471
  12. Redfearn DP, Trim GM, Skanes AC, et al. Esophageal temperature monitoring during radiofrequency ablation of atrial fibrillation. J Cardiovasc Electrophysiol. 2005;16:589–593
  13. Perzanowski C, Teplitsky L, Hranitzky PM, et al. Real-time monitoring of luminal esophageal temperature during left atrial radiofrequency catheter ablation for atrial fibrillation: observations about esophageal heating during ablation at the pulmonary vein ostia and posterior left atrium. J Cardiovasc Electrophysiol. 2006;17:166–170
  14. Cummings JE, Schweikert RA, Saliba WI, et al. Assessment of temperature, proximity, and course of the esophagus during radiofrequency ablation within the left atrium. Circulation. 2005;112:459–464
  15. Noheria A, Kumar A, Wylie JV, et al. Catheter ablation vs antiarrhythmic drug therapy for atrial fibrillation: a systematic review. Arch Intern Med. 2008;168:581–586
  16. Singh TM, d'Avila A, Doshi SK, et al. Esophageal injury and temperature monitoring during atrial fibrillation ablation. Circ Arrhythm Electrophysiol. 2008;1:162–168
  17. Yamane T, Matsuo S, Date T, et al. Visualization of the esophagus throughout left atrial catheter ablation for atrial fibrillation. J Cardiovasc Electrophysiol. 2006;17:105
  18. Berjano EJ, Hornero F. A cooled intraesophageal balloon to prevent thermal injury during endocardial surgical radiofrequency ablation of the left atrium: a finite element study. Phys Med Biol. 2005;50:N269–N279
  19. Herweg B, Johnson N, Postler G, et al. Mechanical esophageal deflection during ablation of atrial fibrillation. Pacing Clin Electrophysiol. 2006;29:957–961
  20. Chugh A, Rubenstein J, Good E, et al. Mechanical displacement of the esophagus in patients undergoing left atrial ablation of atrial fibrillation. Heart Rhythm. 2009;6:319–322
  21. Dixit S, Marchlinski FE. How to recognize, manage, and prevent complications during atrial fibrillation ablation. Heart Rhythm. 2007;4:108–115
  22. Sanchez-Quintana D, Cabrera JA, Climent V, et al. Anatomic relations between the esophagus and left atrium and relevance for ablation of atrial fibrillation. Circulation. 2005;112:1400–1405
  23. Nakagawa H, Ikeda A, Shah DC, et al. Role of contact force in esophageal injury during left atrial radiofrequency ablation. Heart Rhythm. 2008;15:S68
  24. Rumbak MJ, Chokshi SK, Abel N, et al. Left phrenic nerve paresis complicating catheter radiofrequency ablation for Wolff-Parkinson-White syndrome. Am Heart J. 1996;132:1281–1285
  25. Durante-Mangoni E, Del Vecchio D, Ruggiero G. Right diaphragm paralysis following cardiac radiofrequency catheter ablation for inappropriate sinus tachycardia. Pacing Clin Electrophysiol. 2003;26:783–784
  26. Lee BK, Choi KJ, Kim J, et al. Right phrenic nerve injury following electrical disconnection of the right superior pulmonary vein. Pacing Clin Electrophysiol. 2004;27:1444–1446
  27. Sanchez-Quintana D, Cabrera JA, Climent V, et al. How close are the phrenic nerves to cardiac structures? (Implications for cardiac interventionalists). J Cardiovasc Electrophysiol. 2005;16:309–313
  28. Cappato R, Calkins H, Chen SA, et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation. 2005;111:1100–1105

 The University of California, Los Angeles, has intellectual property relating to this area of work. This study was supported by National Institutes of Health grant nos. IH RO1-HL084261 and HL067647 (to KS).

PII: S1547-5271(09)01034-0

doi:10.1016/j.hrthm.2009.09.022

Heart Rhythm
Volume 7, Issue 1 , Pages 81-87, January 2010

Article Tools

* Image Usage & Resolution