Richard A Hopkins

The median sternotomy is performed in the usual way. Cannulation is accomplished as high on the ascending aorta as possible or as femoral artery cannulation.We use a single atrial return cannula but bicaval cannulation is preferred by some authorities or by us when other reconstructive procedures are needed in the patient.1-3 Left ventricular venting is accomplished via the right superior pulmonary vein. Mild total body hypothermia is used with car-dioplegic arrest supplemented by topic slush cooling. Multiple doses of cold blood cardio-plegia are delivered antegrade at 20 minute intervals via direct coronary cannulas and retrograde as well. We use a high-dose aprotinin protocol and heparin bonded cardiopulmonary circuits (Carmeda) for Ross operations.

After cannulation and cooling has begun, the outside of the heart is examined. Measurements are made at the base of the pulmonary artery trunk and the base of the aorta to give a rough estimate of external size to compare to the measurements being made with the trans-esophageal echocardiography probe. Examination of the aorta and pulmonary artery externally gives some idea as to whether there might be distortions that would prevent Ross type reconstructions. Once the heart is empty and cooling has progressed, the pulmonary artery dissection is begun. The pulmonary artery is separated from the aorta with blunt and sharp dissection, preferably performed as much as possible with the electrocautery (Figure 41.1).This dissection is relatively extensive and extends down to the base of each great vessel. Care is taken to identify the origin of the right coronary artery and to get a feel for the external position of the left main coronary artery, although not necessarily completely exposing it at this stage. The pulmonary artery is transected just below the bifurcation and the pulmonary valve inspected (Figure 41.2). At this stage, the operation can be abandoned if there are congenital or acquired abnormalities of the pulmonary valve that would preclude its use for a Ross operation. We do this prior to cross-clamping the aorta so that cross-clamp time has been saved if alternative prostheses are needed (eg. homograft, stentless valve, etc.). The aorta is now cross-clamped and the heart is stilled with an infusion of cold blood cardio-plegia (if there is severe aortic insufficiency, the heart is stopped with retrograde cold cardio-plegia first and then the aorta opened. Antegrade cardioplegia is now delivered if necessary via direct soft cardioplegia cannula. The aorto-tomy is selected based on the intended backup plan (if the Ross procedure is not utilized). Thus, a transverse aortotomy is performed if a stentless porcine valve insertion is envisioned. If a root replacement with a porcine root is envisioned, then any type of aortotomy can be performed. We tend to use a modified "hockey stick" incision if a backup plan for a traditional manufactured prosthesis is contemplated (Figure 41.3). The aortic valve is now examined and excised. The annulus of the pulmonary artery is measured with Hegar dilators internally, carefully placed inside the valve leaflets and then matched to the aortic size. Alterna

Figure 41.1. Dissecting the pulmonary artery from the aorta. Inset emphasizes LAD coronary.

tively manufacturers' valve sizers can be used with the intent of assessing whether the pulmonary artery is the same or larger than the aorta. The best repairs appear to be with the pulmonary valve internal annulus size being at least two millimeters larger than the aortic internal diameter. If the aortic annulus is more than 6 mm larger than the pulmonary artery diameter, then we do not use aortic annulus reduction techniques but instead abandon the Ross operation. Although David, Elkins and others have reported annulus adjustment techniques, we have avoided their use except in the most compelling of circumstances and as such have yet to have late aortic insufficiency develop in a Ross procedure due to acute or gradual annular dilatation.4-6 If there is significant calcification of the aortic annulus, then geometric mismatch is even less tolerable as the ability to reduce the aortic annulus is less. Enlargement of the aortic annulus is easily accomplished with Manouguian or Nicks type of techniques but reduction in size can be fraught with late failure.7

If the geometric match appears appropriate then attention is turned to excising the pulmonary valve. An incision is made in the right ventricular outflow tract, well below the level of the valve. There is usually a muscular clear space where no fat is present which is marker for the infundibulum well beneath base of the pulmonary valve. Our incision begins at that point and is angled up towards the annulus on either side (Figure 41.4).The incision is brought around the right side of the pulmonary trunk to the back of the annulus at which time the left

Figure 41.2. Pulmonary artery transected. Pulmonary valve inspected.
Figure 41.3. Aortic incision is determined by the backup operations. Ross procedure is best with high transverse.
Figure 41.4. Incision in the right ventricular outflow tract to excise pulmonary valve.

coronary artery is visualized in the bed of fat behind the pulmonary artery and bluntly dissected away from the pulmonary trunk (Figure 41.5). The dissection of the left side of the pulmonary artery resection is now performed extremely carefully, keeping the scissors in a cephalocaudad orientation and parallel to the floor. This helps the operator stay away from the first septal perforator artery (Figure 41.6). If the septal artery can be visualized, then it can easily be avoided. Often it cannot be visualized and by staying very close to the pulmonary annulus, damage is avoided. As the final separation is accomplished, the pulmonary valve complex is retracted towards the patient's left knee and the incision is brought across the posterior fibrous connection, keeping the left coro nary artery cephalad and posterior to the incision (Figure 41.7).

Cardioplegia is usually repeated at this point and the coronary buttons excised. These buttons are excised as large sinus buttons. They can always be trimmed smaller later on as necessary (Figure 41.8). Minimal dissection is performed at the base of the right and left coronary artery to increase their mobility. Stay sutures are applied to the top of each and retracted away from the aortic root as the aortic root is being excised (Figure 41.9). Debride-ment of the annulus is performed. Care is taken to avoid any damage to the mitral valve. Incision down to the level of the muscle for at least a part of the aortic root excision at the left anterior septal portion of the dissection ensures the

Figure 41.6. Pulmonary valve retracted superiorly gives access to posterior base in muscle.

Figure 41.7. Final separation of pul-

Figure 41.7. Final separation of pul-

Figure 41.8. Left and right coronary sinuses excised.

Aortic Root Resection

aortic root expands slightly. Alternatively, if the annulus size is "perfect" then some fibrous tissue on the aortic root base cylinder can be left circumferentially to aid in suture placement.8-11

Sutures are placed as simple sutures through the aortic annulus base and then through the base of the pulmonary valve. We tend to work from the left side along the posterior row first, working towards the surgeon on the right side of the table (Figure 41.10). Once the posterior 180° has been accomplished, the final clamp is clipped inside the jaws of the Allis clamp and can be laid down on the drapes superiorly, thus keeping the posterior row of sutures in order.

The orientation of the pulmonary valve complex is made by definition with the placement of this posterior suture row by commit ting the middle portion of the larger sinus of the pulmonary valve to the left coronary sinus region with an eye to simplifying placement of the left coronary button. It is preferable to plan to place the left coronary button slightly higher than it originally was on the aorta, but with minimal distortion in any other direction (Figure 41.11). Given good placement, stretching the left main coronary artery more than 1 mm cephalad is not necessary. The anterior row of simple sutures is placed, once again working from the patient's left side to the right side and thus working toward the surgeon (Figure 41.12). Once all sutures have been placed, a strip of Teflon felt, 2mm in width, is slipped through the sutures as the autograft is parachuted down into the base of the aortic outflow. The Teflon is dampened with saline containing

Figure 41.10. Figure of posterior row simple sutures. Each suture is placed in its own clamp and slipped over an Allis clamp to maintain orientation.
Figure 41.11. Alignment of left coronary button to its new sinus of the autograft.

antibiotics to help in its caulking function (Figure 41.13).

The sutures are sequentially tied, working sequentially from the surgeon's side and tying each suture sequentially moving from right to left. We prefer to tie the posterior row so that the inside "seating" can be checked. The anterior row is completed and the sutures tied. Our preference for suture material is 3-0 (in adults) or 4-0 (in children and neonates), coated braided suture (Tycron©: on the Tycron brand suture material we prefer the T16 needle). The left coronary button is sutured to its position on the posterior sinus. A small button of autograft tissue is excised. A somewhat larger button of aortic wall tissue is left around the coronary ostia and sutured to the orifice with a running

5-0 polypropylene suture technique, either working from posteriorly or occasionally working from inside the autograft, whichever is simpler (Figure 41.14). Usually at this point, we similarly place the right coronary button in its respective sinus. There is usually a bit more "play" with the right button. We take care to more it superiorly and then either to the right or the left as is necessary to avoid tension. If it is difficult to arrange the button, then the distal suture line can be accomplished first and then the button sutured. The advantage of suturing the right coronary button prior to the distal anastomosis is that damage to the pulmonary valve leaflet can be avoided and that suturing can be accomplished from both inside and outside as necessary. For smaller children or

Figure 41.13. Seating of autograft. Felt inside suture loops, outside neo-aortic base.
Figure 41.14. Coronary buttons being sutured.

neonates, we use 6-0 or 7-0 polypropylene for the buttons (Figure 41.14).The distal suture line is accomplished with a running polypropylene suture reinforced with a strip of Teflon felt. The suture is usually 4-0 polypropylene for adults and 5-0 for children. The reinforcement Teflon felt is helpful as the distal pulmonary artery autograft tissue is often quite thin. The elasticity of the pulmonary artery leads to great flexibility in this distal anastomosis, but as necessary, incisions in the aorta or plication to tailor its size is sometimes necessary (Figure 41.15).

Restoration of the right ventricular outflow tract is accomplished. A homograft has been thawed of appropriate size. We prefer a pul monary valve but do not hesitate to use an aortic valve homograft if necessary. The valve graft is sized to be the size of the patient's own valve or larger. There is significant expansion of the right ventricular outflow orifice as a consequence of the "V" infundibular incision and thus it is often easier to select a homo-graft larger than the native; we routinely "upsize" the RVOT valve in pediatric Ross operations.1213

The distal anastomosis of the homograft to the pulmonary artery just below the bifurcation is accomplished with a running 5-0 (adult) or 6-0 (pediatric) polypropylene suture (Figure 41.16). No Teflon felt is used in this anastomosis. It is our preference to accomplish this anas-

Hemi Pulmonary Artery Homograft
Figure 41.16. PA anastomoses distal first. Length (for clarity) of PA homograft depicted longer than is typical. Should keep segment short to "suspend" semilunar pulmonary valve complex.

tomosis prior to removing the cross clamp. Cardioplegia can be delivered via the aortic root needle which is in the aortic root above the level of the distal anastomosis at this stage which allows for checking of the integrity of all of the aortic suture lines. We initiate this with cold cardioplegia which continues the myocar-dial protection while additional sutures are placed in the aorta or distal pulmonary artery anastomosis. This step also allows visualization of any coronary arterial leaks in the muscle of the right ventricular outflow tract which can be easily electrocauterized for hemostasis. Once hemostasis is felt to be adequate, then cardioplegia is changed to warm (hot shot) cardioplegia for five minutes as the suturing of the proximal pulmonary artery homograft is accomplished. This suturing is begun left and posteriorly in the region of the first septal perforator which allows the most accurately placed sutures (Figure 41.17). A strip of Teflon felt is placed at the posterior base of the right ventricular orifice and the sutures are place either through or around this as the base of the homo-

graft is sutured to the right ventriculotomy. These sutures are the secured at either end of the posterior suture line with additional sutures. Suture material is polypropylene of a 3-0 size for adults and, 4-0 size for children and 5-0 in neonates and infants. Once the posterior suture line of the right ventricular outflow tract has been secured, the aortic cross-clamp is removed. De-airing maneuvers are performed. Throughout the rewarming phase of the patient, continuous suction is applied to an aortic root vent. The anterior reconstruction of the pulmonary outflow tract is completed. There is often enough ventricular myocardium that the suture line can be continued anteriorly with muscle to the annulus of the homograft (Figure 41.18A). Augmentation of the right ventricular outflow tract connection to the anterior base of the homograft results in a smoother reconstruction and aids in upsizing the homograft. A piece of PTFE fashioned from a tube graft slightly larger than the homo-graft (Figure 41.18B), is used for this "gusset" or "hood."

Figure 41.18. Completion. (A) Direct suturing of the muscle to the base of the homograft in the right ventricular outflow tract. Panel (B) PTFE "hood" added to ventricular outflow.

The patient is weaned from cardiopulmonary bypass after full rewarming. The decannulation is performed in the usual fashion. The pericardium is not closed in these patients. Hemostasis has been excellent especially after initiating the aprotinin protocol (vida infra).

Prior to separation from cardiopulmonary bypass, transesophageal echocardiography is performed to look for any gross malfunction of either the pulmonary or aortic valves (vida infra). The patient is weaned from cardiopul-monary bypass and transesophageal echocar-diography repeated. Direct palpation of both the base of the aortic and pulmonary arterial reconstructions is performed and the absence of bruits correlates with absence of insuffi ciency. Blood pressures are maintained at around 100 Torr. In many cases, blood transfusions are not necessary. If there is oozing, then fibrin glue, either home made or manufactured, can be utilized to reinforce the hemostasis of the suture lines.

0 0

Post a comment