Needle-to-suture ratio, as well as suture material, impacts needle-hole bleeding in vascular anastomoses

The purpose of this study was to examine the influence of material variables on needle-hole bleeding in vascular anastomoses. Material variables include suture size, needle-tip geometry and diameter, needle coating, suture material and coating and swage area. We attempted to determine whether particular suture material and a reduced needle-to-suture ratio (N:S ratio) could reduce the vessel wall defect and reduce needle-hole bleeding, without changing the suture diameter used for the anastomosis.

A comparative analysis was made of the needle-hole leak rate in end-to-end anastomoses of an ePTFE®-ePTFE® vascular graft with a PROLENE® polypropylene suture with HEMO-SEAL™ technology (HS, 1.84:1 N:S ratio), standard PROLENE® polypropylene suture (polypropylene 1, 2.41:1 N:S ratio), an alternate standard PROLENE® polypropylene suture (polypropylene 2, 2.06:1 N:S ratio) and a GORE-TEX™ ePTFE® suture (ePTFE® suture, 1.4:1 N:S ratio) in an ex vivo cardiopulmonary bypass pulsatile flow loop model using heparinized porcine blood. Testing was completed within the model with an activated clotting time between 250 and 500 s, at near normothermia (33-35°C) and at normotensive pressure levels (120/80 mmHg). A sample size of n = 20 was completed for each group.

The average total sample leak rate was 19.8 ± 4.5 ml/min for the HS suture, 57.2 ± 7.2 ml/min for polypropylene 1, 33.8 ± 4.1 ml/min for polypropylene 2 and 46.5 ± 10.3 ml/min for the ePTFE suture. The average needle-hole leak rates were 0.63 ± 0.13 ml/min for the HS suture, 1.94 ± 0.23 ml/min for polypropylene 1, 1.14 ± 0.14 ml/min for polypropylene 2 and 1.56 ± 0.34 ml/min for the ePTFE® suture. A two-sided 95% confidence interval for the difference in leak rates showed that there were significant differences (44-67% reduction) in favour of the HS suture when compared with the alternative needles with the same suture material and different N:S ratios, and also a reduction (59%) compared with the sample with smaller N:S ratios but different suture material.

The N:S ratio as well as the physical characteristics of the suture material are important factors in reducing needle-hole bleeding in vascular anastomoses.