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Ann Thorac Surg 1999;68:1871-1872
© 1999 The Society of Thoracic Surgeons
a Herzzentrum, University of Leipzig, Russenstrasse 19, D-04289 Leipzig, Germany
Invited commentary
In a timely review of the various surgical options for dealing with a left superior vena cava (SVC) associated with unroofed coronary sinus or drainage to the coronary sinus, Dr Zimand and colleagues present 4 patients with a left SVC, 2 of whom had an unroofed coronary sinus, in whom the left SVC was ligated. Although ligation of the left SVC can almost always be performed without mortality, the real issue is how much morbidity (cerebral and upper limb edema, petechiae, etc) one is prepared to accept and how long it will take for adequate venous collateral circulation to develop. Although none of the 4 patients in this series had long-term neurologic complications, ultrasonographic examination of the brain in 1 patient demonstrated mild to moderate enlargement of the cerebral ventricles, which is a worrisome finding.
In the situation of a small left SVC associated with unroofed coronary sinus, especially in the presence of an innominate vein, ligation of the left SVC certainly is the most expedient operation, and can be performed without untoward effects. In the presence of a large left SVC without innominate vein and associated with unroofed coronary sinus, however, ligation of the left SVC in many cases results in prohibitively elevated left superior caval and intracranial pressures. In this situation, the usual repair consists of resection of the atrial septum (when present), followed by placement of a pericardial patch in such a fashion that all of the pulmonary veins drain under the baffle to the mitral valve orifice. The proximity of pulmonary veins to the orifice of the left SVC makes the placement of such a baffle cumbersome with the inherent potential for pulmonary venous obstruction or left SVC obstruction, or both. Another major concern with regard to the latter technique relates to the creation of a small and low-compliant left atrial compartment with its adverse effect on left ventricular filling. These concerns apply especially when the intraatrial baffle repair is performed in complex forms of unroofed coronary sinus syndrome, often in association with partial or complete atrioventricular canal. The cumulative effects of creation of a small and low-compliant left atrial compartment in the setting of increased volume loading (as a result of abolition of the left-to-right shunt) of the (often relatively small) left ventricle may be incompatible with postrepair survival. This is evidenced by reported high mortality rates for biventricular repair of complex unroofed coronary sinus.
In an attempt to tailor the operative technique to the unique physiology of the patient with left SVC and unroofed coronary sinus, several extracardiac techniques have recently been developed for this combination of anomalies. The advantage of these techniques consists of avoidance of construction of an intraatrial baffle, thus neutralizing the various disadvantages that are inherent to the latter technique. In addition, the extracardiac techniques are more straightforward technically and allow for a reduction in myocardial ischemic time. In the unique situation of a large left SVC and a restrictive innominate vein, the left SVC can be divided and the diminutive innominate vein can be augmented with an autologous pericardial patch [1]. In the much more common situation of a large left SVC without innominate vein associated with unroofed coronary sinus, adequate mobilization of both SVCs including the right brachiocephalic vein, the azygos vein, and the bilateral proximal internal jugular veins and subclavian veins, may allow detachment of the left SVC from the left atrium and anastomosis to the right SVC in the anatomical position of the innominate vein [2]. Division of the left SVC with a cuff of left atrial wall helps in creating an anastomosis that is free of tension. If a course of the left SVC anterosuperior to the aortic arch is technically not feasible, a course under it may be a good alternative [3]. In the absence of a right SVC or in the presence of a diminutive right SVC, consideration may be given to anastomosis of the left SVC to the tip of the right atrial appendage [3]. Alternatively, in patients beyond the neonatal stage, a bidirectional left superior cavopulmonary anastomosis may be performed [4]. Although aneurysm formation in this circumstance has been reported [5], bidirectional cavopulmonary anastomosis in the presence of pulsatile flow in the pulmonary artery system is well established in the literature, and in my experience. Thus, this complication is unlikely to be a major concern, as long as this approach is limited to patients with low pulmonary vascular resistance.
A large left SVC associated with dilated coronary sinus may sometimes lead to partial obstruction of left ventricular inflow and, in the presence of an atrial septal defect, increase the shunt volume across the atrial septum. For this combination of anomalies, Cochrane and co-workers [6] reported segmental resection of the dilated coronary sinus wall followed by reconstruction. In this setting, an extracardiac repair technique may also be a surgical option, although this operation, based on the presence of redundant coronary sinus tissue, may result in only partial resolution of the obstructive effect.
References
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