Ann Thorac Surg 2007;84:652-654
© 2007 The Society of Thoracic Surgeons
Case Reports
Partial Cardiac Denervation and Sinus Node Modification for Inappropriate Sinus Tachycardia
Tsuyoshi Taketani, MD,
Randall K. Wolf, MD*,
Jeffrey V. Garrett, MD
Section of Cardiothoracic Surgery, Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
Accepted for publication March 12, 2007.
* Address correspondence to Dr Wolf, 231 Albert B. Sabin Way, Cincinnati, OH 45267–0558 (Email: wolfr{at}ucmail.uc.edu).
| Dr Wolf discloses that he has a financial relationship with Atricure.
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Abstract
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We describe a case of inappropriate sinus tachycardia refractory to medical therapy and catheter sinus node ablation, which was successfully treated by surgery with approaches on both the sinus node and cardiac autonomic ganglia.
Inappropriate sinus tachycardia (IST) is a disorder characterized by a consistently elevated sinus rate and an excessive increase in response to minimal physiologic activity. For treatment, intervention and surgical techniques to ablate or isolate the sinus node have been reported. However, recurrence of IST or eradication sinus node function has been the common outcomes of these methods.
A 43-year-old woman was referred for surgical treatment of IST. She had begun to feel palpitation 2 years before, sustained a fall, and was noted to have tachycardia. She continued to be symptomatic, detailing episodes of shortness of breath and experiencing chest discomfort, despite her medical regimen of beta blockers, calcium channel antagonists, and anti-arrhythmics. Autonomic testing with propranolol and atropine revealed that her intrinsic sinus rate was 105 beats/minute, and as such, she was diagnosed with IST. Activation mapping of the right atrium was performed. Then she underwent radiofrequency catheter ablation of the sinus node twice. Radiofrequency energy was delivered at the endocardial breakthrough of the sinus node until the P wave became flat in II and inverted in aVF, and P wave changes persisted up to 1 hour post radiofrequency. However, sinus tachycardia recurred 3 months after each of the two procedures, and her heart rate remained at 110 to 130 beats/minute at rest and increased to 160 to 200 beats/minute with exercise.
The patient underwent partial cardiac denervation and sinus node modification through a 6-cm right thoracotomy without cardiopulmonary bypass. Her heart rate was 100 beats/minute after induction of anesthesia, and during the procedure isoproterenol was continuously administered to achieve sinus tachycardia of 130 beats/minute. After the right chest cavity was entered, a pericardiotomy was made anterior and parallel to the right phrenic nerve. Right pulmonary veins were encircled using a lighted dissector (Wolf Lumitip Dissector [Atricure, West Chester, OH]). Then an ablation line was created on the antrum of the left atrium and the base of the superior vena cava with a bipolar radiofrequency clamp (Isolator ENDO-xcR [Atricure]). Then fat tissue on the epicardium of the atria, superior vena cava, aorta, and right pulmonary artery was ablated with another radiofrequency device (Isolator Transpolar Pen [Atricure]). Finally, a lesion on the right atrial wall was created at the right atrium, at the superior vena caval junction up onto the right atrium for 3 cm using the same device as shown in Figure 1. By these maneuvers the heart rate dropped to 100 beats/minute under isoproterenol challenge without a change of P wave morphology. After discontinuing isoproterenol, her heart rate was approximately 70 beats/minute. Her postoperative course was uneventful. She has been in sinus rhythm with normal P waves and a heart rate of 70 to 80 without exaggerated increase during exercise for 6 months after surgery.
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Fig 1. Schematic representation of the technique used in this case. Arrows show lines of isolation on the superior vena cava and the antrum of the left atrium. Gray area shows ablated atrial wall and fat tissue on the epicardium and great vessels. Area marked with oblique lines is the estimated sinus node region.
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Comment
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Causes of IST have not been well elucidated, but enhanced intrinsic automaticity of the sinus node, altered autonomic responses due to sympathetic receptor hypersensitivity, and increased sympathetic tone or blunted parasympathetic tone have been proposed as potential mechanisms [1, 2]. Previous literatures regarding the treatment of IST involved targeting the sinus node alone by excision [3], ablation and modification [2, 4], or isolation [5] of the sinus node. However, we believe that modulation of the cardiac autonomic nerve has never been attempted for the treatment of IST. This seems to be in part because it is difficult to treat extracardiac autonomic ganglia with a catheter-based approach, and in part because most patients with IST show high intrinsic sinus rates with pharmacologic autonomic blockade test [1], which might rule out the role of the autonomic nervous system on the mechanism of IST. However, the fact is that a significant proportion of patients who underwent procedures on sinus node alone (either interventionally or surgically) had recurrence of IST or required pacemaker implantation because of resultant junctional bradycardia [2–4]. This implies that there is great difficulty associated with the ablation of sinus nodal pacemaker cells to an extent just enough to restore normal sinus node function due to their anatomy and physiology [4]. In this case, in addition to ablating a part of the right atrial tissue in the sinus node area, we tried interrupting autonomic nervous input to the sinus node completely by isolating right pulmonary veins, superior vena cava, and ablating fat tissue surrounding the sinus node with a successful outcome at least at the time of this writing. This is quite a natural idea considering the possible cause of IST; therefore we believe this minimally invasive procedure can be a choice for patients with IST, although follow-up of the patient is needed to verify its long-term efficacy.
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References
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- Morillo CA, Klein GJ, Thakur RK, Li H, Zardini M, Yee R. Mechanism of "inappropriate sinus tachycardia": role of sympathovagal balance Circulation 1994;90:873-877.[Abstract/Free Full Text]
- Shen WK. How to manage patients with inappropriate sinus tachycardia Heart Rhythm 2005;2:1015-1019.[Medline]
- Esmailzadeh B, Bernat R, Winkler K, Meybehm M, Pfeiffer D, Kirchhoff G. Surgical excision of the sinus node in a patient with inappropriate sinus tachycardia J Thorac Cardiovasc Surg 1997;114:861-864.[Free Full Text]
- Koplan BA, Parkash R, Couper G, Stevenson WG. Combined epicardial-endocardial approach to ablation of inappropriate sinus tachycardia J Cardiovasc Electrophysiol 2004;15:237-240.[Medline]
- Kreisel D, Bailey M, Lindsay D, Damiano Jr RJ. A minimally invasive surgical treatment for inappropriate sinus tachycardia J Thorac Cardiovasc Surg 2005;130:598-599.[Free Full Text]
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Abstract
Introduction
