Two-Patch Repair of Atrioventricular Septal Defect

While complete atrioventricular septal defect covers a wide spectrum of malformations and pathophysiologies, there are several phenotypic features common in all of them. The phenotypic features are the commonality of the atrioventricular junction, the atrioventricular valve leaflets inserted at same level of crux, unwedged and anteriorly displaced aortic valve, an elongated left ventricular outflow tract (or a gooseneck deformity), a cleft left atrioventricular valve component, and counterclockwise rotation of left ventricle papillary muscles.

While there are several types of complete balanced atrioventricular septal defects, this video focuses on Dr. James Tweddell’s two-patch repair technique for this lesion. The patient in this video had a Rastelli type A defect, but Dr. Tweddell’s technique did not vary based on the Rastelli classification. Dr. Tweddell almost always chose the two-patch repair technique, with some notable exceptions. Dr. Tweddell primarily used the one-patch technique with 0.4 mm expanded polytetrafluoroethylene patch in patients with tetralogy of Fallot and atrioventricular septal defect with a larger outlet component of the ventricular septal defect.

To begin, a standard median sternotomy was performed. Antibiotic-soaked laparotomy pads were placed along the sternal edges and a Morse sternal retractor was inserted. A subtotal thymectomy was then performed. The aorta was separated from the main pulmonary artery and Heparin was administered. The ascending aorta, superior vena cava, and inferior vena cava purse-string sutures were placed.

Next, the patient was cannulated onto an aortobicaval cardiopulmonary bypass. Cardiopulmonary bypass was then initiated. The ligamentum was circumferentially dissected and ligated with a titanium clip prior to initiation of full-flow cardiopulmonary bypass. An antegrade cardioplegia cannula was placed in the aortic root and the aortic cross-clamp was applied. Cold cardioplegia was then delivered and the patient was cooled to 32 °C. Caval snares were lowered and the right atrial free wall was incised. The incision began near the base of the right atrial appendage and was extended caudally, parallel to the atrioventricular groove and terminating between the medial surface of the inferior vena cava and right coronary artery. Then, the atriotomy edges were suspended with stay sutures and the intracardiac anatomy was inspected. The atriotomy edges were suspended with stay sutures and a vent was placed in the right upper pulmonary vein and left atrial junction.

The diagnosis of complete balanced atrioventricular septal defect was confirmed. There was a large ostium primum atrial septal defect, an unrestrictive inlet ventricular septal defect, and a common atrioventricular valve orifice with bridging leaflets across ventricular septum. The common atrioventricular valve was classified as a Rastelli type A. There is a superoanterior bridging leaflet divided over and attached medially to the crest of septum, with the left superoanterior bridging leaflet entirely over the left ventricle and the right superoanterior bridging leaflet entirely over the right ventricle.

The common atrioventricular valve was then floated with ice-cold saline. The zone of apposition (cleft of the left atrioventricular valve) was approximately the equal length of coapting segments of the left superoanterior and left inferoposterior leaflets. The base of the left atrioventricular valve cleft was defined at the contact point between the left superoanterior and inferoposterior leaflets, corresponding to the plane of the ventricular septal defect projected vertically from the crest of the septum. The extent of the left atrioventricular valve cleft was the location where the primary chords insert into the free edge of the leaflets. Both sites were marked on both leaflets with simple 7-0 polypropylene sutures. The sites can be revised once the ventricular component is closed, and the cleft is addressed.

The ventricular component of the defect was addressed first. The crest of the ventricular septum was measured with a free silk tie and the leaflet height was measured as well. A crescent moon shape was cut from a patch of bovine pericardium. The ventricular septal defect patch was then secured to the right side of the crest of the ventricular septum to avoid the conduction axis. A single limb of a double-armed pledget-supported 5-0 polypropylene was passed through the crest of the septum and was then passed through the superoanterior crux. The crux was defined as the atrioventricular valve and atrial septum junction. The remaining limb of the suture was then passed through the corresponding edge of the patch and then passed through the crux. This process was repeated at the inferoposterior crux, with an additional pledget-supported 5-0 polypropylene. A third double-armed pledget-supported 5-0 polypropylene was passed through the right side of the septal crest and patch at the midpoint. The patch was then secured to the septum, running the limbs of the double-armed polypropylene in opposite directions from the midpoint to the superoanterior and inferoposterior cruxes. Both arms were passed through the corresponding crux and tied to the previously placed crux sutures.

The left superoanterior and inferoposterior bridging leaflets were then secured along the superior edge of the patch. A series of horizontal mattress sutures of 6-0 polypropylene were passed through the superior edge of the patch followed by the adjacent leaflet. The edges of the superoanterior and inferoposterior leaflets on the right atrioventricular valve can be attached as well, but this is not always necessary and was not completed in this case.

The atrial component of the defect was then addressed. A large rectangular patch was cut from bovine pericardium and trimmed at a later time. The series of horizontal mattress sutures passed through the superior edge of the ventricular septal defect patch were passed through the inferior edge of the atrial septal defect patch. The sutures were then tied, securing the patch. The inferoposterior edge of the atrial septal defect patch was left long to sew around the coronary sinus. This was done to ensure avoidance of the atrioventricular node, which lies more posterior and inferior to normal.

The left atrioventricular valve cleft was then addressed. The atrial septal defect patch was reflected into the right ventricle. The zone of apposition was reassessed and, ultimately, closed with a series of simple interrupted 8-0 Gore-Tex (ePTFE) sutures. The valve was then sized and float tested multiple times to ensure that it was not stenotic or regurgitant.

Any concomitant valvar defects were addressed at this time. In this specific video, the left atrioventricular valve was supported by a single papillary muscle. This resulted in a crowded subvalvar region. The subvalvar apparatus was opened by splitting the papillary muscle and dividing any tertiary chords. The valve was again sounded and float tested. A small leak was identified at the anterolateral commissure. A double-armed pledget-supported 5-0 polypropylene commissural annuloplasty suture was placed.

A small patent foramen ovale was identified and closed with a single horizontal mattress suture of 5-0 polypropylene. The atrial septal defect patch was then trimmed to size.

The atrial component of the defect was then closed. The remaining arm of the continuous suture at the inferoposterior atrioventricular junction was run continuously between the coronary sinus and the inferior vena cava orifice. The coronary sinus was on the left side. The remaining arm at the superoanterior atrioventricular junction was run continuously, meeting the opposite suture, and tied.

The right atriotomy was closed with a dual-layer 6-0 polypropylene and caval snares were released. Deairing maneuvers were then performed and the aortic cross-clamp was removed. Modified ultrafiltration was then performed. The patient was successfully weaned and separated from cardiopulmonary bypass. The patient was then decannulated, hemostasis was achieved, temporary pacing wires and chest tubes were placed, and the chest was closed. The patient was then transported to the cardiac intensive care unit.
 

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