Joseph Dearani, M.D., Chair, Cardiovascular Surgery, Mayo Clinic: My name is Joseph Dearani, and I'm the chair of Cardiovascular Surgery at the Mayo Clinic in Rochester, Minnesota, and my area of expertise is in pediatric and congenital heart disease. Today we are going to talk about tetralogy of Fallot, which is one of the most common congenital heart defects. In many ways, this lesion is viewed as the benchmark against which other treatment strategies for congenital heart defects are compared. There is no other lesion that offers the breadth of treatment history, and modifications to further improve results, that continue to the present day.

The optimum treatment approach remains controversial, but in general, complete repair is advised in the first three to six months of life. Importantly, the application of the modified Blalock–Taussig shunt as a palliative procedure is performed much less commonly in the current era. The surgical goal is complete repair, which consists of ventricular septal defect closure and relief of right ventricular outflow tract obstruction, which is ideally performed with preservation of pulmonary valve function. The most common congenital heart operation performed in adulthood is pulmonary valve replacement following tetralogy of Fallot repair in infancy or childhood.

There are two standard approaches for complete repair. The first is the transatrial-transpulmonary approach and the second is the transventricular approach. The transatrial-transpulmonary approach has the distinct advantage of preserving pulmonary valve function but may be better approached, and a little bit easier, beyond four months of age. Selective use of a small infundibular incision may be helpful to completely relieve right ventricular outflow tract obstruction and/or improve visualization of the ventricular septal defect in some situations. A concerted effort is made to stay below the pulmonary annulus, and preserve the pulmonary valve when this is performed, particularly if the size of the pulmonary valve annulus is acceptable, thus requiring pulmonary valvotomy alone. The transventricular approach can be applied at any age. While it has stood the test of time, we have learned that many patients ultimately require pulmonary valve replacement later on in life because of pulmonary regurgitation. Consequently, if the transventricular approach is being applied, extensive transannular patching is avoided in order to minimize late right ventricular dilatation and right ventricular dysfunction, severe pulmonary regurgitation, and avoiding ventricular arrhythmias. While it is important to adequately relieve right ventricular outflow tract obstruction, leaving some residual obstruction behind is considered acceptable, particularly if preservation and function of the pulmonary valve can be maintained. In general, a residual gradient of 20 to 30 millimeters of mercury across the pulmonary valve is usually well tolerated and permissible.

The presence of an anomalous left anterior descending coronary artery is usually not a contraindication to complete repair in the current era. A short transannular incision can be performed that avoids the anomalous left anterior descending coronary artery and can be utilized to further relieve right ventricular outflow tract obstruction, if needed. The decision to close the patent foramen ovale is largely determined by patient age and whether a transannular repair was applied. In general, the patent foramen ovale is left open when complete repair is performed in the neonate or when a transannular repair has been performed and severe pulmonary regurgitation is present. The application of a monocusp repair to improve competence of the pulmonary valve can be helpful in this situation and can smooth out the early post-operative period.

In the modern era, repair of tetrology of Fallot can be performed with very low mortality, in the neighborhood of 1%, and the late survival and quality of life are excellent for the majority of patients. In general, children attend school and can participate in most childhood sport activities without restrictions. Early repair in the first six months of life is the rule, and preservation of the pulmonary valve and minimizing pulmonary regurgitation is the goal. The need for diligent lifelong surveillance cannot be overemphasized, so that proper timing of any potential subsequent interventions can be optimized.

Mayo Clinic has a long-standing history in the surgical care of tetrology of Fallot since the earliest days of cardiac surgery in the mid 1950s. The number of patients in our practice that have undergone complete repair, or palliative procedures, or re-operations later on in life, in childhood and adulthood, with tetrology of Fallot are now in the thousands. Thank you very much for listening on tetrology of Fallot.

Oct. 28, 2023