Ann Thorac Surg 2004;78:1988
© 2004 The Society of Thoracic Surgeons
INVITED COMMENTARY
Scott M. Bradley, MD
Division of Cardiothoracic Surgery, Medical University of South Carolina, 96 Jonathan Lucas St, Charleston, SC 29425, USA
bradlesm{at}musc.edu
There is compelling logic to the argument that the extracardiac conduit approach to the Fontan procedure should minimize or avoid arrhythmias. Compared with the lateral tunnel approach, the extracardiac conduit limits atrial suture lines, and avoids exposure of any portion of the atrium to high pressure. At first glance, the report of Nürnberg and colleagues supports this argument: extracardiac conduit patients had lower rates of sinus node dysfunction and supraventricular tachycardia both in-hospital, and during follow-up. This report contains a large amount of information and deserves careful scrutiny. Several points are of interest. Despite the minimization of atrial surgery, patients undergoing an extracardiac conduit Fontan procedure have an incidence of sinus node dysfunction at the time of hospital discharge of approximately 15%. This has been a consistent observation (summarized in their Table 1), being seen in the current report (16%), as well as in reports from the Hospital for Sick Children, Toronto (15%), Children's Hospital of Philadelphia (13%), and Medical University of South Carolina (17%). The reasons for this are unclear, but may include the effects of atrial incisions for associated procedures or fenestration placement, or damage to the sinus node or its blood supply during redissection.
The incidence of sinus node dysfunction after the lateral tunnel approach has been more variable. Some of this variation may be related to the approach to Fontan staging, and its effect on the particular technique of the lateral tunnel procedure. Although a hemi-Fontan procedure involves an incision at the cavoatrial junction, a subsequent lateral tunnel procedure is carried out without incisions, suturing, or redissection in the region of the sinus node and its blood supply. Two reports indicate that a hemi-Fontan–lateral tunnel approach has an incidence of sinus node dysfunction as low as an extracardiac conduit approach [1, 2]. In Nürnberg's report, only 5 of 29 (17%) lateral tunnel procedures followed a previous hemi-Fontan, whereas 17 of 29 (59%) included an incision across the cavoatrial junction. A cavoatrial incision was the only significant risk factor for postoperative bradyarrhythmia, highlighting the importance of the technical approach to the lateral tunnel procedure. Early sinus node dysfunction was, in turn, a significant risk factor for late supraventricular tachycardia.
While this study adds to our knowledge, the question of the relative arrhythmogenic potential of the extracardiac conduit and lateral tunnel procedures remains incompletely answered. A randomized comparison of the two approaches is unlikely. Given this, a more complete answer could be provided by prospective follow-up, including regularly scheduled Holter electrocardiograms, of patients undergoing consistent technical approaches to both preliminary staging and completion Fontan procedures.
References
- Cohen MI, Bridges ND, Gaynor JW, et al. Modifications to the cavopulmonary anastomosis do not eliminate early sinus node dysfunction. J Thorac Cardiovasc Surg. 2000;120:891–901[Abstract/Free Full Text]
- Kumar SP, Rubinstein CS, Simsic JS, Taylor AB, Saul JP, Bradley SM. Lateral tunnel versus extracardiac conduit Fontan procedure: a concurrent comparison. Ann Thorac Surg. 2003;76:1389–1397[Abstract/Free Full Text]
