Tetralogy of fallot surgical techniques
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, MBBS [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]
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Surgical procedures
Blalock-Taussig shunt — Blalock and Taussig first reported successful surgical palliation of TOF in 1945 [5]. The procedure, which has since come to bear their names, used a subclavian artery to create an aorta-to-pulmonary artery connection. The success of this procedure changed the previously dismal outlook for this disease. The technique has been modified and is now usually performed using a Gortex tube to create the connection. (See 'Subclavian steal' below.)
Although most children with TOF undergo intracardiac repair as their initial intervention, the principle of the Blalock-Taussig shunt remains an important palliative procedure for infants who may not be acceptable candidates for intracardiac repair due to prematurity, hypoplastic pulmonary arteries, or coronary artery anatomy.
Intracardiac repair — Intracardiac repair of TOF was reported by Lillehi in 1954 [6]. It consists of patch closure of the ventricular septal defect and enlargement of the RVOT. The latter is accomplished by relieving pulmonary stenosis, resecting infundibular and subinfundibular muscle bundles and if necessary by a transannular patch, creating unobstructed flow from the RV into the pulmonary arteries (figure 2).
The goal of initial surgery should be to relieve all sources of RVOT obstruction, including that located at the site of insertion of the ductus arteriosus, which may be difficult to diagnose in the neonate before ductal closure. When feasible, a transatrial approach is utilized to access the right ventricular outflow tract and close the ventricular septal defect. This approach is most likely to be successful in patients with discrete infundibular stenosis and an adequate pulmonary annulus [7]. A transpulmonary approach allows additional access to the right ventricular outflow tract, however, ventriculotomy with right ventricular outflow tract enlargement and even transannular patch may be required for adequate relief of outflow tract obstruction.
A transannular patch of the RVOT renders the pulmonary valve incompetent, which may have significant long-term hemodynamic and electrophysiologic consequences, especially if severe. Currently, surgical approaches emphasize maintaining pulmonary valve competence where possible. A "valve sparing approach" is easily applied to individuals with adequate pulmonary annulus size. However, in patients with borderline pulmonary valve annulus sizes, this approach necessitates balancing some degree of residual right ventricular outflow tract obstruction against the obligate insufficiency associated with a transannular patch.
The ability to preserve the pulmonary valve was illustrated in one study in which 80 percent of children who underwent repair had a valve sparing procedure, primarily through a transatrial-transpulmonary approach [8]. Residual outflow tract gradients fell in the valve-sparing group at a mean follow-up of 34 months (range 4 to 84 months) compared to a slight increase in the patients with transannular patch repair [8], similar to results from another case series [7]. Reoperation rates for patients undergoing valve sparing procedures were not statistically different from the reoperation rate for patients with a transannular patch repair and were low for both groups. Use of an initial palliative shunt appeared to improve the success of a valve sparing approach, especially in symptomatic young infants with small pulmonary valves.
At the present time, there is not general consensus upon the size of the pulmonary annulus and the acceptable degree of residual outflow tract obstruction that is amenable to a valve sparing approach [7-9]. Guidelines continue to evolve as additional data become available. The most common current surgical strategy consists of ventriculotomy and transannular patch repair for primary repair, as well as repair of TOF after palliation [10].
An alternate procedure is insertion of a valved conduit from the RV to the distal main pulmonary artery (figure 2). However, stenosis and/or regurgitation of the conduit prosthetic valve, as well as stenosis of the conduit, can occur [11]. (See 'Chronic pulmonary regurgitation' below.)
Palliative surgery
- The condition was initially thought untreatable until surgeon Alfred Blalock, cardiologist Helen B. Taussig, and lab assistant Vivien Thomas at Johns Hopkins University developed a surgical procedure. It was actually Helen Taussig who convinced Alfred Blalock that the shunt was going to work.
- The surgery involved forming an anastomosis between the subclavian artery and the pulmonary artery. This redirected a large portion of the partially oxygenated blood leaving the heart for the body into the lungs, increasing flow through the pulmonary circuit, and greatly relieving symptoms in patients.
- The first Blalock-Thomas-Taussig shunt surgery was performed on 15-month old Eileen Saxon on November 29, 1944 with dramatic results.
- The Pott shunt and the Waterson procedure are other shunt procedures which were developed for the same purpose.
- Currently, Blalock-Thomas-Taussig shunts are not normally performed on infants with TOF except for severe variants such as TOF with pulmonary atresia.
- The Blalock-Taussig procedure was the only surgical treatment until the first total repair was performed in 1954.
Total surgical repair
- The total repair was performed by C. Walton Lillehei at the University of Minnesota in 1954 on a 10-month boy.
- Total repair initially carried a high mortality risk which has consistently improved over the years.
- Surgery is now often carried out in infants 1 year of age or younger with a <5% perioperative mortality.
- The surgery generally involves
- Making incisions into the heart muscle, relieving the right ventricular outflow tract stenosis by careful resection of muscle
- Repairing the VSD using a Gore-Tex or Dacron patch or a homograft.
- Additional reparative or reconstructive work may be done on patients as required by their particular anatomy.
- Patients who have undergone "total" repair of tetralogy of Fallot often have good to excellent cardiac function after the operation with some to no exercise intolerance and have the potential to lead normal lives. Surgical success and long-term outcome greatly depends on the particular anatomy of the patient and the surgeon's skill and experience with this type of repair.
See also
- Trilogy of Fallot
- Pentalogy of Fallot
References
External links
- Tetralogy of Fallot information from Seattle Children's Hospital Heart Center
- Information by University of Michigan Health System
- Diagram of the condition
- Information for adults with ToF from the Adult Congenital Heart Association
- Michael Warman's Website on ToF
de:Fallot-Tetralogie it:Tetralogia di Fallot nl:Tetralogie van Fallot nn:Fallots tetrade uk:Тетрада Фалло