Surgical Considerations for Congenital Heart Disease

Chapter 70

Surgical Considerations for Congenital Heart Disease

Congenital cardiac defects may be categorized in a variety of ways. One approach is to separate them based on the presence or absence of cyanosis in the patient presenting to the pediatric cardiologist or cardiac surgeon. Cyanotic lesions are associated with shunting of deoxygenated blood into the systemic arterial circulation or with severely reduced pulmonary blood flow. These lesions include transposition of the great arteries, tetralogy of Fallot (TOF), truncus arteriosus, total anomalous pulmonary venous connection, and hypoplastic left heart syndrome (HLHS). Acyanotic lesions include (1) obstructions to left ventricular outflow, such as aortic stenosis or coarctation of the aorta, and (2) defects with shunting of blood from the systemic circulation to the pulmonary circulation, including atrial, ventricular, and atrioventricular septal defects and patent ductus arteriosus (PDA). Often a combination of lesions exists, and associated anomalies must be thoroughly identified by preoperative imaging studies. This chapter will review the pathophysiology and clinical and imaging evaluation of patients with congenital heart disease as they relate to surgical planning. Discussion will reference treatments, particularly with regard to choice of surgical approach, along with intraoperative and postoperative considerations pertinent for radiologists.

Surgical Approaches

Surgery for congenital heart disease is most commonly performed via a median sternotomy incision. Such an incision involves an anterior midline thoracic incision with dissection through the subcutaneous tissues down to the sternum. Once the sternum has been exposed, a sternal saw is used to split the sternum and a retractor is placed to define the operative field within which the pericardial sac is contained (Fig. 70-1). Because this incision offers excellent access to all of the structures contained within the mediastinum, including all chambers of the heart, ventricular outflow tracts, and venous returns, it is useful when multiple lesions are present or if a complicated repair must be performed.

Less invasive options for repair of congenital heart lesions also exist, such as a partial median sternotomy or a thoracotomy. In the case of a partial median sternotomy, the skin incision is kept small and only the upper or lower sternum is divided (e-Fig. 70-2). Depending on the necessary exposure, thoracotomy incisions can be anterior, lateral, or posterior (e-Fig. 70-3). Historically, thoracotomy incisions involved the sectioning of a rib; in general these incisions now are made simply by dividing the intercostal muscles and leaving the ribs intact.

The type of lesion being repaired determines the choice of surgical incision. Straightforward repair of extracardiac lesions such as aortic coarctation, vascular rings, or PDA generally can be performed through a left thoracotomy (e-Fig. 70-4). In addition, in the case of simple intracardiac repairs such as an atrial septal defect (ASD), a minimally invasive approach can be used even though the operation requires the use of cardiopulmonary bypass (CPB). As techniques have been refined in recent years, interest has increased in operating on simple defects, as well as the mitral, tricuspid, and aortic valves, through minimally invasive incisions. In addition, interest has developed in performing relatively straightforward operations, including some heart valve surgery, using thoracoscopic or robotic techniques. In these cases, several very small incisions are made through which specially designed instruments can be placed and used to perform the procedure (e-Fig. 70-5). Advantages touted include an improved cosmetic result and potentially shorter recovery times inside and outside the hospital.

For most complex congenital heart defects, such as repair of an atrioventricular (AV) septal defect lesion, a median sternotomy is used. In this case the repair includes a right atriotomy, closure of a ventricular septal defect (VSD), repair of the ASD, and partitioning of the common AV valve into right and left components, with closure of the “cleft” in the left-sided AV valve (e-Fig. 70-6). Additionally, repair of cyanotic lesions typically requires the use of a median sternotomy incision. The reasoning is that these lesions often require greater exposure of both intracardiac and extracardiac structures that need to be repaired. One example of the need for a median sternotomy incision is a repair in a patient with TOF where an approach through the right atrium and the pulmonary artery is needed to close the VSD and relieve the right ventricular outflow obstruction. In some cases in which a very small pulmonary annulus or significant infundibular stenosis is present, the incision might even need to be extended to the right ventricular cavity (e-Fig. 70-7).

The choice of surgical approach also is important in the case of staged operations. A patient with HLHS generally will undergo three operations for complete palliation, and the need for a repeat sternotomy carries both operative and radiographic implications. Radiographically, imaging of the chest can help with operative planning because repeating median sternotomy incisions carries a greater risk of damage to the thoracic contents as a result of the formation of postoperative adhesions. For example, the aorta or other structures can be found very close to the sternum (e-Fig. 70-8) and might be damaged upon entry to the chest during the sternotomy, requiring the emergent institution of CPB. Careful review of chest imaging and the potential use of alternative, peripheral cannulation (discussed later) can help make the redo operation safer. Lesions that commonly require multiple operations include HLHS, TOF, and truncus arteriosus.

Other scenarios influencing operative planning and the choice of incision include the presence of multiple lesions or when a complete repair is not indicated and a palliative procedure is indicated instead. Many congenital heart defects can occur together, such as coarctation of the aorta and VSD. In this case, a surgical procedure that might have been accomplished through a thoracotomy incision for isolated coarctation (e-Fig. 70-9

Dec 20, 2015 | Posted by in PEDIATRIC IMAGING | Comments Off on Surgical Considerations for Congenital Heart Disease
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