The Damus-Kaye-Stansel Operation

Introduction

his operative procedure is typically used in double inlet left ventricle, tricuspid atresia with {SDD} transposition of the great vessels, and {SLL} transposition of the great vessels with a hypoplastic right ventricle in which systemic outflow is dependent on an intraventricular foramen, and the potential for subaortic stenosis exists at the intraventricular foramen, the outlet chamber or the aortic valve.

Cardiopulmonary bypass and deep hypothermic circulatory arrest

Pre-cardiopulmonary bypass consideration:

  • Aprotinin, solumedrol, Regitine, Phenobarbital and antibiotics are given preoperatively. PGE1 is discontinued. The room temperature is lowered as much as possible to start surface cooling.
  • A sternotomy is performed and the heart suspended in a pericardial cradle. The patient is heparinized, and the right branch pulmonary artery is controlled. Occasionally, a purse-string is placed around the right atrial appendage and retracted downwards in order to facilitate exposure.

Cannulation:

  • An aortic purse string in the mid-ascending aorta. The venous purse string is a single large one around the right atrial appendage, in order to facilitate later atrial septectomy.
  • The aorta and atrium is cannulated.

Cardiopulmonary bypass and deep hypothermic circulatory arrest:

  • cardiopulmonary bypass is started and cooling to 18 - 20 C is started.
  • For patients less than 3 months of age or 5 kg, the operation is performed under deep hypothermic circulatory arrest, otherwise, low-flow deep hypothermic cardiopulmonary bypass is preferred. Following institution of cardiopulmonary bypass, the head is packed in ice, and the ventilator is turned off.
  • Pulmonary blood flow is controlled by controlling an arterial duct if present, by snaring both branch pulmonary arteries, or by cross-clamping the main pulmonary artery.

The dissection

Dissection of the aorta, pulmonary artery, and head vessels; preparation of the homograft:

  • Dissection begins by dissecting the aorta away from the pulmonary artery. The aorta is dissected completely from its root to the head vessels. The head vessels are completely mobilized. The innominate artery is dissected above the innominate vein, and both the right subclavian and right carotid arteries are mobilized and encircled with silk snares. The left carotid and subclavian arteries are likewise completely mobilized and encircled with silk snares.
  • The pulmonary artery is completely mobilized. More dissection than appears necessary is done. It is during this part of the dissection that the left carotid and subclavian arteries are completely mobilized.
  • The homograft patch is prepared from an appropriately sized pulmonary homograft. The inlet portion and the valve itself are discarded. The widest portion of the homograft patch is chosen as that at the inlet side, and is tailored to tapers with a nice curve towards the longest of the two branch pulmonary arteries. It is best not to make the homograft too wide.
  • The Prolene stitch that is used to sew the homograft may be placed at this time.

Protection of the heart and brain

  • A period of 20 minutes of core cooling to 18 - 20 C with the head packed in ice is considered minimum cerebral protection.
  • The pump is turned off and the patient drained into the venous reservoir.
  • The head vessels are snared down and the aortic cannula is removed.
  • 30 cc/kg of cold-blood potassium cardioplegia is administered via a catheter placed through the aortic purse string.
  • The field is cleared as much as possible for the palliation: The branch pulmonary artery snares are released, but generally not removed, as these may later aid in exposure when working on pulmonary blood flow.
  • The arterial duct, if present, is tied off, and the venous cannula removed.

Resection of the septum primum

  • The septum primum is resected:
  • It is first attempted through the venous purse-string. If the atrial septum is deviated leftwards so that its exposure is difficult, that a small atriotomy is made along the right atrioventricular groove, and the septum is resected. The coronary sinus may be cut back into the left atrium at this time.

Aorto-Pulmonary Anastomosis

  • The pulmonary trunk is divided at it’s bifurcation
  • The underside of the distal ascending aorta to the proximal ascending aorta is made to the point where the aorta exactly meets with the facing commissure of the proximal end of the divided pulmonary artery. The reverse-bite Potts scissors is best for opening the undersurface of the aorta. The incision starts distally and proceeds proximally. The first-assistant gently retracts the divided lip of the aorta to aid in exposure. It is extremely important not to spiral this incision. It is often best to pick up the exact point of where the pulmonary artery meets the ascending aorta, and using the reverse-bite Potts, to make a straight incision connecting the two points.
  • The proximal aorta is anastomosed to the pulmonary artery with wither a continuous or interrupted 7-0 absorbable suture.
  • A stay stitches is placed on the upper lip of the aortic incision at the base of the innominate artery in order to facilitate exposure.
  • The homograft is sewn into place, starting distally and working proximally. The posterior row is placed first, and the closure is done up to the innominate stay-stitch. Next, the anterior row is placed and is completed up to the innominate stay-stitch.
  • The length of the homograft is next assessed. Any extra length is removed, by gauging how long the homograft should be in order to meet the divided proximal end of the main pulmonary artery. With the assistant holding the homograft and the pulmonary artery together, the extra homograft tissue is removed from the posterior row. Generally, all that is extra is removed. No extra tissue is generally removed from the anterior row.
  • The posterior row is now completed, going ‘around the horn’ of the homograft - pulmonary artery anastomosis, and up to the aortic anastomosis. The anterior row is completed up to the posterior row, and the stitch tied and cut.

Restoration of cardiopulmonary Bypass

  • The atrium and aortic root are filled with cold normal saline, and the aortic and venous cannulae are replaced. cardiopulmonary bypass is resumed, and any air in the systemic circulation is allowed to flow down the aorta. The head vessel snares are released and removed.

Restoration of pulmonary blood flow

  • The distal divided end of the pulmonary artery is patched with GoreTex or homograft.
  • The size of the shunt chosen is based on the weight of the patient, and the estimated amount of pulmonary blood flow.
  • For patients with normal or near-normal appearing chest films and preoperative saturation greater than 80 percent, the size of the shunt in mm is approximately the weight in kilograms, (e.g. for a 3.5 kg baby, a 3.5 mm shunt is generally used). The more congested the chest film is, the lower the saturation, and the greater the weight of the baby, the larger the shunt. For premature babies less than 3.0 kg, a 3.0 or 3.5 mm shunt is generally chosen.
  • The systemic arterial side of the shunt is performed first. The anastomosis is performed on the posterior aspect of the innominate-subclavian artery junction in an end-to-side fashion using polypropylene suture.
  • The pulmonary side of the shunt is performed next. The site of the anastomosis is chosen to lie as close to the ductus insertion site as possible, and in a few recent patients, the ductus insertion site on the pulmonary artery was resected and the shunt sewn into this position. In this way, flow is equalized to both the left and right pulmonary arteries.
  • Following completion of the shunt, a clamp is applied to the shunt until weaning from cardiopulmonary bypass is started.