Transventricular Repair of Tetralogy of Fallot

Cardiopulmonary bypass is instituted with an aortic and two venous cannulae. After clamping the aorta, blood cardioplegic fluid is infused into the proximal aorta and the cavae snugged. A longitudinal incision is made in the right ventricle stopping a few millimeters short of the pulmonary valve.

The obstructing muscle in the right ventricular outflow tract is excised and the VSD can be inspected.

The pulmonary valve is inspected from below and any cuspal fusion incised. The annulus size is then measured with Hegar dilators, and the maximum diameter that will comfortably accept a Hegar dilator is compared with the acceptable diameter for that size of patient as noted in Pacifico’s tables.⁵ The VSD is closed with a patch, as shown in .

If the annulus diameter is acceptable, the longitudinal right ventriculotomy is closed with an elliptical-shaped patch. Autologous pericardium, which has been soaked in gluteraldehyde for 10 minutes is very satisfactory, but Dacron or Goretex can be used, though the latter two may bleed more.

If the annulus diameter is inadequate, the incision is carried upwards through the pulmonary valve to the bifurcation of the main pulmonary artery. If there is a proximal narrowing in one of the individual pulmonary arteries, the incision should be continued across this. When making the incision through the pulmonary valve ring, it is best to try to take the incision between cusps so as to preserve the cusps if possible. If a unicusp transannular patch is used, the remaining cusps will help to reduce regurgitation. With retractors at the lower end of the ventriculotomy, a good view is obtained of the VSD, but it is unnecessary to extend the incision downwards, and usually the ventriculotomy in an infant need not be more than 1.5 to 2 cm.

A retractor is placed in the upper margin of the VSD and, with upward retraction, a better view of the lower margin of the VSD is achieved. The tricuspid valve abuts the lower edge of the defect and the bundle of His is indicated in the diagram. Care must be taken to avoid this when suturing. The aortic cusps can be seen through the upper right margin of the VSD and great care must be taken to avoid damaging them with sutures.

The VSD is closed with a patch of Dacron, Goretex, or calf pericardium. A running stitch is very satisfactory and several sutures can be placed before pulling the patch down into position.

After pulling the patch down, the sutures are continued in a clockwise direction, taking care to keep on the right side of the septum. In the region of the bundle of His, it is safer to place the sutures in the base of the tricuspid valve leaflet. Particularly if the tissue here is rather thin, extra pledgeted sutures can be used. The other end of the continuous suture is used to run round in an anticlockwise direction and the knot tied at the top. The use of sutures of 5/0 prolene is very satisfactory for infants and of 4/0 for older children.

The transannular patch is then inserted with a continuous suture. Care must be taken not to pull the sutures too tight as this can have a “pursestring” effect, causing a distal stenosis. The patch should not be too wide, or excessive regurgitation will occur. If a unicusp patch is used, it is important to get the anterior cusp at the same level as the residual pulmonary cusps. This will minimize initial regurgitation, but as the patient grows, pulmonary regurgitation will inevitably occur. It is possible to insert a transannular patch with the heart beating, having released the aortic clamp. In either case, it is important to remove all air from the left side of the heart. Once the heart is beating well, bypass can be discontinued. A pressure needle should be inserted through the right ventricle into the left ventricle. This is then pulled back into the right ventricle and virtually simultaneous LV and RV pressures are measured. The post operative pRV/LV should be less than 0.8 if adequate relief of RVOTO has been achieved. When a transannular patch has been inserted, it is usually much less.