In some patients with intermittent claudication blood flow to the calf muscles after exercise was in the same range as in normals. The blood pressure was lower in all patients. The hypothesis is formulated that for these high flow patients the claudication is a result of non-uniform perfusion of the calf muscles.
The peripheral vascular runoff is a predictor of graft patency especially in the popliteal and peroneal section. Scoring systems of the preoperative angiogram only give qualitative data. Intraoperative measurement allows quantification of peripheral vascular resistance. Here, a perfusion system for caversonography was used.
Between February 1989 and June 1991 the peripheral outflow resistance was measured at 45 patients during infragenual bypass surgery. In order to find out whether there is a correlation between successful bypass grafting and measured outflow resistance, all patients were controlled regularly. There was a significant difference in mean resistance between those grafts remaining patent and those that failed. 8 out of 11 bypasses, that failed up to one month after operation, had measured peripheral resistance higher than 1.1 mmHg x min/ml. 12 out of 15 bypass grafts remained patent for more than one month and had an outflow resistance less than 0.55 mmHg x min/ml. There is no definite correlation between a measured outflow resistance from 0.55 to 1.1 mmHg x min/ml because of the low number of patients in this group. The purpose of resistance measurement during peripheral vascular surgery was to determine a final value for a decision, if additional surgical or non surgical treatment for a better runoff is necessary. In our study this value is 1.1 mmHg x min/ml. Additional treatments are the peripheral AV-fistula and a jump- or sequential-graft. Another possibility is the intra- and postoperative application of Prostaglandin, which is in an experimental study in our clinic.
A calf ergometer is presented that can be used for both static and dynamic exercise in supine, sitting or standing position. During exercise each foot is fixed firmly to a pedal. During dynamic exercise the foot pedal can rotate through an angle which can be varied from 5 to 30 degrees. External work is performed only during plantar flexion. The amount of work is determined by the moment imposed to the pedal by a constant force spring and can be calculated from electrical signals that represent the angle of rotation and the moment exerted to the pedal. During static exercise the foot pedal is secured so that it cannot move.
Vascular run off has an important influence on patency rates of infrapopliteal bypasses especially when prosthetic grafts are used. Construction of a distal arteriovenous fistula can improve volume and velocity of graft flow. 39 patients, 14 of them diabetic, had femoro-crural PTFE-bypasses. A distal arteriovenous fistula in common ostium technique was established in 20 cases. The patency rate (early occlusions) was improved, especially diabetic patients seemed to profit by lowering the peripheral outflow resistance, which was measured intraoperatively. The influence of arteriovenous fistulas of different calibre on bypass flow and perfusion was analysed in a circulation model.
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