A DYNAMIC STUDY OF THE CIRCULATION IN THE GRACILIS MUSCLE IN HUMANS

The aim of the present study was an evaluation of the relative importa nce of the proximal and distal pedicles for the perfusion of the graci lis muscle flap, as well as to evaluate the importance of the function al connections between the proximal and distal vascular territories. T en gracilis muscles were investigated in nine patients. They were all operated on in the supine position under general anesthesia. Microcirc ulatory blood flow (MBF) in the muscle was measured by a dual-channel laser Doppler flowmeter. Two angled probes were sutured opposite to th e entry of the proximal and distal pedicles into the muscle, and were kept in place throughout the measurements. Data were acquired on line via a multichannel interface with acquisition/analysis software to a p ortable computer. The following measurements were done: during baselin e with both pedicles intact; during occlusion of the proximal pedicle; after clamp release; during occlusion of the distal pedicle; after cl amp release; after motor-nerve transection; and after disinsertion of the muscle from bone attachments. After clamping the proximal pedicle, MBF decreased proximally to 57 +/- 5 percent (p < 0.01), but remained unchanged distally. After occlusion of the distal pedicle, MBF remain ed virtually unchanged proximally (92 +/- 4 percent, NS), but decrease d to 72 +/- 6 percent (p < 0.05) distally. There was a significantly g reater decrease in MBF when the proximal pedicle was clamped, than aft er clamping the distal pedicle (p < 0.01). There was a strong linear c orrelation (r = 0.85) between the proximal and distal MBF after occlus ion of the corresponding pedicle. Transection of the motor nerve resul ted in a moderate increase in MBF values proximally (130 +/- 10 percen t, p < 0.05), but not distally (108 +/- 18 percent, NS). Detachment of the muscle led to a distinct increase of MBF in both vascular territo ries (proximally 175 +/- 28, percent p < 0.05; distally 157 +/- 20 per cent, p < 0.05). These measurements demonstrated the dominant role of the proximal pedicle in the gracilis muscle in humans. Furthermore, it was shown that each of the two pedicles (proximal and distal) has its own vascular territory, and that both territories are partially conne cted by intramuscular vascular anastomoses. The predictable extent of blood flow Varies in individual cases and should be measured intraoper atively. In cases of marginal perfusion to the distal part of the musc le, a delay procedure should be considered.