Dimensional analysis of human saphenous vein grafts: Implications for external mesh support
Received 11 March 2008; received in revised form 5 September 2008; accepted 3 October 2008. published online 23 February 2009.
Objective
Constrictive external mesh support of vein grafts was shown to mitigate intimal hyperplasia in animal experiments. To determine the degree of constriction required for the elimination of dimensional irregularities in clinically used vein grafts, a detailed anatomic study of human saphenous veins was conducted.
Methods
In 200 consecutive patients having coronary artery bypass grafting, harvested saphenous veins (length 34.4 ± 10.8 cm) were analyzed regarding diameter irregularities, side branch distribution, and microstructure.
Results
The mean outer diameter of surgically distended saphenous veins was 4.2 ± 0.6 mm (men, 4.3 ± 0.6 mm vs women, 3.9 ± 0.5 mm; P < .0001). Although the outer diameter significantly decreased over the initial 18 cm (−7.6%; P < .0001), the overall increase between malleolus and thigh was not significant (+11.2%). Smaller-diameter veins (<3.5 mm) had more pronounced diameter fluctuations than larger veins (31.8% ± 11.0% vs 21.2% ± 8.8%; P < .0001), with more than 71% of all veins showing caliber changes of more than 20%. There was 1 side branch every 5.4 ± 4.3 cm, with a significantly higher incidence between 20 and 32 cm from the malleolus (P < .0001 to distal, P < .0004 to proximal). Generally, women had more side branches than men (0.30 ± 0.15 cm−1 vs 0.25 ± 0.12 cm−1; P = .0190). Thick-walled veins (565.7 ± 138.4 μm) had a significantly higher number of large side branches (P < .0001), and thin-walled veins (398.7 ± 123.2 μm) had significantly more small side branches (P < .0001). Pronounced intimal thickening (“cushions”) was found in 28% of vessels (119.8 ± 28.0 μm vs 40.1 ± 18.2 μm; P < .0001).
Conclusion
Although the preferential location of side branches may be addressed by the deliberate discarding of infragenicular vein segments, a diameter constriction of 27% on average would eliminate diameter irregularities in 98% of vein grafts.
Christiaan Barnard Department of Cardiothoracic Surgery, University of Cape Town, Observatory, South Africa
Address for reprints: Peter Zilla, MD, PhD, Christiaan Barnard Department of Cardiothoracic Surgery, Cape Heart Centre, Faculty of Health Sciences, University of Cape Town, Anzio Road, 7925 Observatory, South Africa.
Dr Zilla reports royalty agreements and grant support from Medtronic. Drs Human and Franz report salary and grant support from Medtronic. The Medtronic grant also funded development of an external mesh support for vein grafts.
ABSTRACT