In contrast to earlier reports, this prospective study up to 12 years after deep vein thrombosis demonstrates a low incidence of postthrombotic syndrome by administration of oral anticoagulants and regular compression therapy. However, the adverse clinical event rate (mortality 14%) and a recurrence rate of 24% show that the prognosis after deep vein thrombosis does not appear favorable even in low-risk patients.
The transparent oxygen electrode, recently developed by Huch and his co-workers, permits monitoring of transcutaneous oxygen tension (tcPo2) at defined sites on the capillaroscopic image obtained by videomicroscopy. This combined system has been applied to study the nutritional skin capillaries of patients with chronic venous incompetence (CVI). 806 simultaneous measurement of the oxygen tension of the skin (tcPo2) and examination of the nutritional skin capillaries at the monitoring site by videomicroscopy. This combined system was applied in the study of 17 patients with CVI and the results were compared with those obtained in a group of 24 healthy subjects.
Materials and methodsPatients. The CVI group consisted of 17 patients (six women, 1 1 men) with a mean age of 56 years (range 22 to 76). Fortyfour measurements were obtained in this group. The method of selection of sites of measurement is described below.In 12 patients CVI was caused by deep venous thrombosis (obstruction and/or incompetence of deep veins, incompetent perforating veins) and in five CVI resulted from primary varicose veins with incompetent perforating veins.Nine patients had trophic skin changes without ulcers and eight had trophic skin changes with ulcers or healed ulcers. The diagnosis was based on patient history, clinical findings, and results of Doppler ultrasound examination. Venograms were obtained in seven patients.No patient had clinical evidence of peripheral arterial occlusive disease. Palpation of pulses, auscultation, and photoplethysmography at the big toe were normal in all cases.Control subjects.
The purpose of this study was to investigate the previously unknown flow velocity in single lymphatic capillaries of humans in the supine position. Fifteen healthy subjects (10 women and 5 men; mean age 35.8 +/- 13.1 yr) were studied. Ten microliters of fluorescein isothiocyanate-dextran (150,000 mol wt) were injected into the subepidermal layer of the foot dorsum. The filling of the microlymphatics from the resulting depot was visualized by fluorescence video microscopy and stored on videotape. Flow velocity in the microlymphatics was determined on the video screen by direct measurement of the advancement of dyed lymph during a given time. The following median velocities were obtained: 0.51 mm/s (0.27 and 0.61 mm/s for lower and upper quartiles, respectively) for velocity during initial network filling and 9.7 microns/s (6.9 and 14.2 microns/s for lower and upper quartiles, respectively) for resting velocity at the end of the filling period. Mean lymphatic capillary diameter was 54.8 +/- 8.2 microns, and mean network extension was 8.3 +/- 3.2 mm. The high filling velocities are probably due to increased interstitial pressure and volume caused by dye microinjection, whereas the values measured during the end of network filling seem to approach resting flow velocities.
In an overview the microvascular involvement in chronic venous insufficiency (CVI) is described. Microangiopathy in the lower leg areas is characterized by the presence of typical enlarged and ramified blood capillaries, reduced capillary number, microvascular thrombosis and obliterations, and/or increased permeability of microlymphatics. Transcutaneous oxygen tension (tcPO2) is decreased and directly correlated to the number of perfused capillaries, whereas laser Doppler flux is enhanced. This apparent paradox may be explained by hyperperfusion in the deeper skin layers (mainly shunt vessels) and hypoperfusion in the superficial nutritive vessels. Microvascular changes are of patchy distribution. Trophic changes up to overt venous ulceration are mainly caused by microvascular ischemia and edema formation due to increased capillary permeability and deficient lymphatic drainage.
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