Repair of Complete Atrioventricular Septal Defect by Two Patch Technique

Complete atrioventricular septal defect (AVSD) is a very challenging surgery, mainly due to the 3D nature of the repair. The goals of surgery for complete AVSD repair are: closure of interatrial communication, closure of interventricular communication, maintaining or creating two competent, nonstenotic AV valves, and avoidance of injury to AV node and bundle of His.

The two patch technique, also called the “sandwich” technique, is a time tested and popular method to repair complete AVSD (1, 2). The main steps in this technique are placement of an initial stitch of the base of the ‘cleft’ of the left AV valve after floating the valve with saline, placing an appropriately sized and shaped VSD patch (Dacron) to the right side of the crest of the inlet septum, attaching the crest of the patch to the AV valvar tissue, and ‘sandwiching’ the frail valvar tissue with a pericardium on the atrial side. A very important component then is the closure of the cleft without everting the edges of the cleft. A pericardial patch is then sutured to close the ostium primum ASD. It is important to make the VSD appropriately sized as too wide a patch leads to distortion of the valvar tissue leading to residual/recurrent left AV valve regurgitation (AVVR), and too long a patch leads to shifting of the coaptation of the left AV valve more anteriorly leading to systolic anterior motion (SAM), leading to gradient in a left ventricle outflow tract (LVOT), which already borderline in size and elongated in AVSD.

The strategies to avoid AV node and bundle of His include:

1. Diverting the coronary sinus routinely to the left atrium at the cost of some insignificant desaturation.
2. Sewing the pericardial patch of the ASD to the base of the left AV valvar tissue taking superficial bites in the region of triangle of Kochs.
3. Following the right atrial wall to suture the ASD patch and going to the bottom of the coronary sinus away from the AV node before transitioning the patch to the primum ASD margin. The latter two strategies preserve the drainage of the coronary sinus to the right atrium.

In this video, the technique of following the right atrial wall, going to the depth of coronary sinus, and then transitioning to the ASD margin is demonstrated to avoid the AV node.

A modified single patch, or the Australian technique, is an alternative to repair complete AVSD, and many studies have shown equivalent results along with the advantage of shorter cross clamp and CPB times (3, 4). However, a recent meta-analysis showed that low operative times do not translate into any different ICU or hospital stays for these patients (5).

The main advantages of the two patch technique for repair of complete AVSD are:

• Maintenance of planar alignment of the AV valves
• Lower chances of narrowing the LVOT
• Preserving the integrity of the bridging leaflets
• Does not compromise ventricular volumes

References

1. Daebritz SH. Correction of complete atrioventricular septal defects with two patch technique. Oper Tech Thorac Cardiovasc Surg. 2004;9:208-220.
2. Dekel H, Zhu J, Coles JG. Repair of atrioventricular septal defects: the 2-patch sandwich technique. Oper Tech Thorac Cardiovasc Surg. 2015;20:63-74.
3. Ugaki S, Khoo NS, Ross DB, Rebeyka IM, Adatia I. Modified single-patch compared with two-patch repair of complete atrioventricular septal defect. Ann Thorac Surg. 2014;97:666–672.
4. Bogers AJJC, Akkersdijk GP, de Jong PL, Henrich AH, Takkenberg JJM, van Domburg RT, et al. Results of primary two-patch repair of complete atrioventricular septal defect. Eur J Cardiothorac Surg. 2000;18:473-479.
5. Loomba RS, Flores S, Villarreal EG, Bronicki RA, Anderson RH. Modified single-patch versus two-patch repair for atrioventricular septal defect: a systematic review and meta-analysis. World J Pediatr Congenit Heart Surg. 2019;10(5):616-623.

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