The deep venous system and reverse flow flaps.

The deep venous system of the upper and lower extremities was injected with a lead oxide mixture in 2 fresh human cadavers, dissected, radiographed and the sites of the venous valves located. These studies confirmed that the macrovenous connections between the venae comitantes of the distributing arteries were insufficient in number to bypass the venous valves in conventional, distally based reverse flow flaps (e.g. radial, ulnar, peroneal) but revealed an alternative microvenous interconnecting pathway which surrounds the artery as the venae arteriosa. This pathway was investigated in a series of distally based reverse flow saphenous flaps in dogs, comparing flaps where the microvenous connections were left intact (non-skeletonised) with those where these vessels were disconnected with the operating microscope (skeletonised). All non-skeletonised flaps survived subtotally or totally whereas total necrosis was observed in 70% of the skeletonised flaps. Finally a series of haemodynamic studies was performed to test valve competency including extrinsic pressure on the valves. It is concluded that the macrovenous and microvenous pathways, coupled with the variable anatomy of the venous valves, are major factors in determining the survival of reverse flow flaps.