Microvascular patch technique with and without Silastic T-tube bypass

Poor patency results in the surgery of small vessels operated on between 1959 to 1964 was demonstrated to be in part due to the long period of occlusion of the operated vessel during surgery and the presence of a foreign body (suture) in the lumen of the vessel postoperatively. New suture techniques and T-tube bypass were introduced at that time. New experimental data have not been extensively sought since that time. To provide further current data regarding the above observations, 110 arterial vessels (60 carotid arteries 1.1 to 1.3 mm in outside diameter (OD) and 50 femoral arteries 0.6 to 0.7 mm OD) were operated on in rats to compare the bypass versus non-bypass and vein patch closure techniques. In 1-mm vessels, patency rates 1 month after surgery were 100% regardless of the use of bypass or type of closure. Improved visualization, better suture material, and improved surgical skill were probably chiefly responsible for this success. The success rate was not as encouraging, however, in vessels of 0.6 mm OD. The following points are brought out: 1) The presence of the bypass causes damage to the intima in 0.6 mm OD vessels and should not be used. Smaller bypasses do not conduct blood well. 2) Bypass is not required in 1-mm vessels as the patency rate is satisfactory and not altered by its use. 3) The major indication for T-tube bypass is in vessels of 1 mm OD and larger, that nourish tissue which would be damaged by vascular occlusion for 20 to 40 minutes. 4) Foreign body (suture) in the lumen is poorly tolerated in 0.6 mm vessels, but can be tolerated more easily in larger vessels. 5) Techniques that limit the amount of suture material in the lumen are indicated in 0.6-mm vessels. 6) After 1 month, suture material has an epithelial covering and if patency has been maintained for that period of time it is likely to remain.