Angioscopic valvulotomy: evaluation of a new miniaturized prototype.
This study compares valvulotomy performed by a new experimental instrument delivered through the angioscope with the standard technique used in the in situ arterial bypass procedure. Eighteen mongrel dogs (approximately 20 kg) were anesthetized and both femoral veins were exposed from the groin to the knee. A 2.5-mm-external-diameter angioscope was passed through the medial saphenous vein to just below the proximal superficial femoral vein valve. Under direct vision, an experimental valvulotome passed through one of the angioscope ports cut the valve leaflets. In the contralateral limb, a Mills valvulotome was inserted in the same fashion and blindly cut the valve. Operative time was recorded and difficulties were noted. Bilateral ascending lower limb venography, animal sacrifice, and removal of the vein segment containing the area of previous valvulotomy for gross and histologic study were performed immediately (n = 3), and at 2 (n = 3), 7 (n = 3), 21 (n = 4), and 42 (n = 5) days after valvulotomy. In each case, both techniques had cut the valve leaflets by visual and histologic evaluation. It took significantly longer to perform the operative procedure with the angioscope (8.0 +/- 3.7 min) than with the Mills valvulotome (0.8 +/- 0.4 min) (P less than or equal to .001, Student's ttest). There was no difference in the patency of the venous system by venographic study but evaluation for a histologically normal venous system was more common with the Mills technique. The angioscopic technique demonstrated 8 of 18 samples to be histologically normal versus 14 of 18 by the Mills technique (P less than or equal to .05, chi-square test). Both techniques are effective in valve leaflet incision. The new angioscope device is more technically demanding (e.g., operative time) and may be more traumatic (e.g., histologic study). However, a gross estimation of luminal damage (venography) does not find the angioscopic method more thrombogenic. The new angioscopically directed device for venous valvulotomy does function effectively. However, adaptation to the in situ bypass technique to replace present angioscopic methods or blind valvulotomy methods requires an appraisal of just what degree of intraluminal trauma is permissible before the risks outweigh the possible benefits.