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Vagaries of the Vagus Nerve: Relevance to Ablationists

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330 EP IMAGE Vagaries of the Vagus Nerve: Relevance to Ablationists ∗ SIEW YEN HO, PH.D., F.R.C.P., F.E.S.C., JOSE´ ANGEL CABRERA, M.D., PH.D.,† and DAMIAN´ SANCHEZ-QUINTANA,´ M.D., PH.D.‡ From the ∗National Heart and Lung Institute, Imperial College, and Royal Brompton and Harefield NHS Trust, London, United Kingdom; †Servicio de Cardiolog´ıa, Fundaci´on Jim´enez D´ıaz, Universidad Aut´onoma de Madrid, Spain; and ‡Departamento de Anatom´ıa Humana, Facultad de Medicina, UEx, Badajoz, Spain Experimental studies have shown that initiation and posterior and anterior vagal trunks that innervate the stomach maintenance of atrial fibrillation can be enhanced by both and pyloric canal and the digestive tract as far as the proximal parasympathetic and sympathetic stimulation.1 Much atten- part of the colon. Our observation on seven normal cadavers tion is now focused on whether the addition of fat pad ab- revealed a mean distance between the bundles of the anterior lation to left atrial ablation may increase efficacy, or reduce esophageal plexus and posterior left atrial endocardium or extent, of ablative lesions required for eliminating atrial fib- veno-atrial junctions of 4.1 ± 1.4 mm (range: 2.5–6.5 mm). rillation.2,3 However, the course of the vagus nerves in re- Injury to the esophagus is now recognized as a potential risk lation to the left atrium and pulmonary veins is largely ig- in atrial fibrillation ablation on account of its close proximity nored until a recent report on 4 patients who experienced to the left atrial wall and the veno-atrial junctions.5-7 Ab- acute pyloric spasm and gastric hypomotility after undergo- lationists should also be aware of other important adjacent ing catheter ablation for atrial fibrillation.4 We demonstrate in structures, including the vagus nerves and the aorta. cadaveric materials large bundles of the anterior esophageal plexus passing external to the pericardial sac but in very close References proximity to the left atrial wall and to the right and left veno- atrial junctions (see Figure). The vagus nerves pass behind the 1. Liu L, Nattel S: Differing sympathetic and vagal effects on atrial fib- rillation in dogs: Role of refractoriness heterogeneity. Am J Physiol root of the lungs and form right and left posterior pulmonary 1997;273(2 Pt 2):H805-H816. plexuses. From the caudal part of the left pulmonary plexus 2. Chiou C-W, Eble JN, Zipes DP: Efferent vagal innervation of the canine two branches descend on the anterior surface of the esoph- atria and sinus and atrioventricular nodes: The third fat pad. Circulation agus joining with a branch from the right pulmonary plexus 1997;95:2573-2584. 3. Schauerte P, Scherlag BJ, Pitha J, Scherlag MA, Reynolds D, Lazzara to form the anterior esophageal plexus. The posterior and R, Jackman WM: Catheter ablation of cardiac autonomic nerves for anterior esophageal plexuses enter the abdomen through the prevention of vagal atrial fibrillation. Circulation 2000;102:2774-2780. esophageal diaphragmatic opening, reuniting to become the 4. Shah D, Dumonceau J-M, Burri H, Sunthorn H, Schroft A, Gentile- Baron P, Yokoyama Y, Takahashi A: Acute pyloric spasm and gastric hypomotility. J Am Coll Cardiol 2005;46:327-330. 5. Kottkamp H, Hindricks G, Austbach R, Krauss B, Strasser B, Schird- J Cardiovasc Electrophysiol, Vol. 17, pp. 330-331, March 2006. ewahn P, Fabricius A, Schuler G, Mohr FW: Specific linear left atrial lesions in atrial fibrillation: Intraoperative radiofrequency abla- Dr. Ho’s research is supported by the Royal Brompton and Harefield Hospital tion using minimally invasive surgical techniques. J Am Coll Cardiol Charitable Fund while Drs. Cabrera and S´anchez-Quintana are supported by 2002;40:475-480. 6. Pappone C, Oral H, Santinelli V, Vicedomini G, Lang CC, Manguso F, Grant SAF2004-06864 from Ministerio de Educaci´on y Ciencia, Spain. Torracca L, Benissu S, Alfieri O, Hong R, Lau W, Hirata K, Shikuma N, Hall B, Morady F: Atrio-esophageal fistula as a complication of Address for correspondence: Siew Yen Ho, Ph.D., F.R.C.P., F.E.S.C., Na- percutaneous transcatheter ablation of atrial fibrillation. Circulation tional Heart and Lung Institute, Guy Scadding Building, Dovehouse Street, 2004;109:2724-2726. ++ London SW3 6LY, United Kingdom. Fax: 44-20-7351-8752; E-mail: 7. S´anchez-Quintana D, Cabrera JA, Climent V, Farr´e J, de Mendon¸ca MC, [email protected] Ho SY: Anatomic relations between the esophagus and left atrium and relevant for ablation of atrial fibrillation. Circulation 2005;112:1401- doi: 10.1111/j.1540-8167.2006.00364.x 1406. Ho et al. Vagaries of the Vagus Nerve 331 Figure. A: An overview of a transthoracic section through a cadaver showing the locations of the vagus nerves (red dotted circles) and the phrenic nerve (yellow dotted circle) relative to the pulmonary veins and left atrium. B: A close-up of the right inferior veno-atrial junction. C: A corresponding histological section in trichrome stain. The minimal distance between the endocardial surface and the nerve is 2.5 mm in this case. Eso = esophagus; LA = left atrium; LI = left inferior; RA = right atrium; RI = right inferior; RS = right superior; PV = pulmonary vein..
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