Suture techniques for atrioventricular valves: experimental study.

Repair of the complete atrioventricular canal defect is still complicated by dehiscence of sutured atrioventricular valves. An in vitro study of initial suture line strength during tensile loading was made using canine pericardial leaflets. Type of "non-pledgetted" stitch was not related to suture line strength. Closer spacing of non-pledgetted stitches (1 mm versus 2 mm) increased strength 29% (p less than 0.05). Pledgets increased strength 25% (p = 0.004). Greater depth (3 mm versus 1.5 mm) increased strength 32% (p less than 0.0001) in both pledgetted and non-pledgetted stitches. Larger suture size (4-0 versus 6-0) increased strength minimally. An in vivo study was performed to determine if the positive effect of pledgets on initial stitch strength would persist in a functioning mitral valve during healing. Four incisions were made at the base of the anterior mitral leaflet in dogs and were closed with one horizontal mattress stitch, with or without pledgets. After 1 to 7 days, none of the 16 pledget-supported stitches had disrupted whereas nine of the 16 stitches without pledgets had torn out of the leaflet (p = 0.001). Tensile testing indicated use of pledgets resulted in stronger stitches (p = 0.0005). Results indicate that in the repair of the complete atrioventricular canal defect, pledget-supported sutures should be used. If non-pledgetted stitches are necessary, bites should be deep and closely spaced.