Venous myogenic tone: studies in human and canine vessels.

Active and passive mechanical properties of human saphenous and canine femoral and saphenous vein segments were measured in vitro to assess the degree of pressure-dependent venous myogenic tone (% change in diameter, physiological saline solution vs. Ca(2+)-free solution) in these vessels. Stepwise elevation of intraluminal pressure from 2 to 20 mmHg caused an active myogenic response, which was calcium dependent. Side branches of human saphenous veins (OD at 20 mmHg: 1.92 +/- 0.15 mm control; 2.41 +/- 0.18 mm relaxed) displayed a larger degree of myogenic tone (approximately 25%) compared with dog saphenous (OD: 2.84 +/- 0.16 mm control; 2.89 +/- 0.16 mm relaxed) and femoral (OD: 3.56 +/- 0.32 control; 3.66 +/- 0.31 mm relaxed) veins (2-3%). This alteration in myogenic tone results in over 120% change in lumen capacity for the human saphenous vein, whereas for the dog saphenous and femoral veins, the change in lumen capacity is less than 10%. The vessels showed a constriction to norepinephrine as well as a reversible dilation to Ca(2+)-free perfusion. These results support the hypothesis that an active myogenic response may play an important role in the regulation of vascular capacity in the human saphenous vein, which is subject to substantial pressure variations due to changing orthostatic loads.

[Treatment of thoracic outlet syndrome following fracture of the clavicle with resection of the 1st rib (author's transl)]. / Clavicula-törés gyógyulása után kialakult thoracic outlet-szindróma kezelése az I. borda reszekciójával.

The resection of the first rib with a transaxillary approach has been used in the operative treatment of this condition. This approach is though to have more advantages over the anterior (supraclavicular) or posterior (parascapular) ones. The segment resection of the middle third of clavicle would not seem to be justified in these cases. A case is reported in details, where the results support their concept.