Alfred Bollinger

Prospective 12-Year Follow-up Study of Clinical and Hemodynamic Sequelae After Deep Vein Thrombosis in Low-Risk Patients (Zürich Study)

BACKGROUND No prospective study of the long-term sequelae of more than 10 years after acute deep vein thrombosis exists so far. Therefore, 58 low-risk patients with DVT were included in a prospective study to evaluate the natural history of postthrombotic syndrome. METHODS AND RESULTS Clinical and hemodynamic examinations were performed at the time of admission; after 3, 6, and 12 months; after the 2nd, 3rd, 4th, 5th years; and finally after the 12th year. All patients received heparin initially and oral anticoagulants subsequently. After 12 years, 64% of the patients exhibited normal findings. Mild skin changes were found in 28%, marked trophic changes in 5%, and only one venous ulcer occurred. Regular use of compression stockings was reported by 54% of the patients with multilevel thrombosis. Although mean maximum venous outflow was significantly reduced from the acute event to 12 years later (P<.003) compared with the contralateral leg, a significant (P<.05) improvement was observed 6 months later. Recanalization of calf vein thrombosis was detected by Doppler sonography after 3 months. Sixty-four percent of the multilevel thromboses were recanalized completely or in part after 1 year; in 69%, valvular incompetence was found. CONCLUSIONS 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.

Red blood cell velocity in nailfold capillaries of man measured by a television microscopy technique.

Abstract A television microscopy technique allowing sequential measurements of RBC-velocity in human nailfold capillaries is described. The advantages and limitations of the method are discussed. The physiologic pattern of RBC-velocity was assessed in five normal subjects (six capillaries). The velocity in the arteriolar limb of the capillaries at rest averaged 0.84 ± 0.53 mm/sec (mean diameter 0.0122 ± 0.0024 mm) and in the venular limb 0.47 ± 0.29 mm/sec (mean diameter 0.0152 ± 0.0028 mm). The range of the velocities measured was 0 (on-off flow type) −3.47 mm/sec. Flow was continuous in four subjects with considerable changes of velocity (high standard deviations). In one normal subject an on-off flow pattern was observed. The RBC-velocity patterns in two patients with arterial occlusive disease and with Waldenstroms macroglobulinemia are given as first examples for measurements in clinical conditions. In both cases the mean RNC-velocity was decreased as compared to the normal subjects. The patient with macroglobulinemia showed a marked reduction of the peak velocity (below 0.1 mm/sec), and the patient with hand and finger artery occlusions, an on-off flow type with long periods of RBC-standstill. The method may in the future be used to study changes of the microcirculatory pattern in patients with cardiovascular and hematologic disorders and to evaluate drug or operative therapy.

Patterns of Diffusion through Skin Capillaries in Patients with Long-Term Diabetes

We used intravital fluorescence videomicroscopy to study the pattern of transcapillary and interstitial diffusion in the nail folds of 13 patients with long-term diabetes and of 12 healthy controls. In both groups intravenously injected sodium fluorescein left the intravascular compartment. Its distribution in the pericapillary space and in the remote parts of the interstitial space was measured on single frames of the television tape by videodensitometers that are sensitive to intensities of fluorescent light. In the diabetics the dye passed both physiologic diffusion barriers--the capillary wall and the pericapillary space--in significantly increased amounts (P less than 0.01). The enhanced penetration of the tracer into the remote area caused an early homogeneous, milky blurring of the capillary image, whereas in the controls the pericapillary space remained clearly delineated for as long as 40 to 50 minutes after the appearance of the dye. The altered pattern of diffusion could be explained by increased permeability of the diffusion barriers, or, alternatively, by either changes of the mobility of the dye due to binding of the dye by intravascular or interstitial proteins or abnormal hemodynamics in the microvascular circulation. This technique provides a quantitative, noninvasive method of studying the natural history of diabetic microangiopathy.

Microvascular Changes in Venous Disease: An Update

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.

Popliteal artery compression and force of active plantar flexion in young healthy volunteers

PURPOSE To define the prevalence of popliteal artery occlusion during active plantar flexion in normally active and highly trained young volunteers by measuring plantar flexion force and to assess the force level associated with popliteal artery occlusion. METHODS Eighty-four limbs of 42 healthy subjects were studied. Eighteen subjects were highly trained athletes, and 24 were normally active persons. Plantar flexion was progressively performed in prone position against a scale. Plantar flexion force was measured in kilograms. After determination of the maximum strength (Pmax) of plantar flexion force, the level necessary to occlude the popliteal artery (Poccl) was assessed by continuously monitoring that vessel using color duplex sonography. RESULTS Occlusion of the popliteal artery during plantar flexion was observed in 88.1% of the subjects and 77.4% of the limbs. No significant differences in prevalence were found between athletes and normally active subjects. The popliteal artery occluded at a mean plantar flexion force of 45.1 +/- 11.5 kg, which corresponded with 70.1% +/- 16.8% of the maximum force exerted during the provocation test. Poccl was not significantly different between lower limbs of athletes and nonathletes. Although in lower limbs of athletes the popliteal artery occluded at a significantly lower relative force as compared with normally active subjects (65.6% +/- 17.4% vs 74.5% +/- 17.4% of Pmax; p < 0.02), the difference was a result of two extremely low values found in a female athlete. CONCLUSION Positional occlusion of the popliteal artery during active plantar flexion is commonly found in young healthy volunteers. Prevalence of the phenomenon depends on the force level exerted during active plantar flexion. Popliteal artery occlusion during active plantar flexion is not more frequent in athletes and occurs at a similar force level than in normally active subjects.

Diffusion, pericapillary distribution and clearance of Na-fluorescein in the human nailfold.

An intravital fluorescence videomicroscopy technique is described in an attempt to develop noninvasive methods for the study of transcapillary exchange in human physiology and clinical medicine. The apparatus used consists of a Ploemopak incident light fluorescence microscope and a low light level television camera with linear output. After intravenous bolus injection of Na-fluorescein in 12 healthy subjects the movement of the dye particles in the nailfold was observed and stored on video-tape.Immediately after arrival the dye leaks into a halolike section and later into the more remote parts of the pericapillary space. By moving a densitometric window on an axis transversal to the capillary loop (single frames of the tape), characteristic patterns of fluorescent light intensity distribution were obtained at different time intervals. At the edge to the halo the high pericapillary light intensity decreases abruptly moving further away from the capillary (mean: 10.0 μm) for 20 min and more in each individual indicating the presence of a diffusion barrier at this location between halo and more remote areas. Clearance of the dye is much slower than transcapillary diffusion and lasts approximately 2 h.

Evaluation of Flux Motion in Man by the Laser Doppler Technique

Analysis of flux motion by the laser Doppler technique in the forefoot of healthy controls and patients with peripheral arterial occlusive disease was performed by establishing computerized frequency histograms. It was found that the low frequency components (1-10 cycles/min) are caused by local vasomotion. The prevalence of high frequency flux waves (15-25 cycles/min) is significantly increased in peripheral ischemia compared to normal conditions. After successful reopening of large arteries by angioplasty the prevalence decreases (p less than 0.001). Preliminary results indicate that these high frequency rhythmic fluctuations might by induced by respiration.

Measurement of foot artery blood pressure by micromanometry in normal subjects and in patients with arterial occlusive disease.

Blood pressure was measured continuously in the posterior tibial or dorsalis pedis arteries using an isovolumetric system (steel cannulas of 0.18 mm, external diameter). The systolic values in the ankle arteries of 13 normal subjects at rest (154.3 ± 22.3 mm Hg) exceeded the systolic arm pressure (128.9 ± 20.1 mm Hg, P < 0.001), while diastolic values (69.9 ± 8.7 mm Hg) were not significantly different from the arm pressure. In 13 patients with arterial occlusive disease (AOD) the dicrotic notch, normally situated close to the footpoint of the downslope, was either displaced upward or abolished. Both mean systolic and diastolic values (94.9 ± 35.9 mm Hg and 62.5 ± 18.5 mm Hg, respectively) and also mean pressure amplitude were reduced compared to the corresponding arm values (158.5 ± 28.2 mm Hg and 87.7 ± 6.0 mm Hg, respectively, all P < 0.001). Comparison between the systolic pressure values measured by micromanometry and by an indirect technique using Doppler ultrasound showed a good correlation (r = 0.87). During postocclusive reactive hyperemia, the initial pressure values were markedly diminished in normal subjects and reached control values within 40 sec. In patients with AOD, however, this reduction in pressure was more pronounced and prolonged. Flow measurements using plethysmography showed flow diversion from the foot to the calf as long as pressure values ranged below 40 mm Hg. This almost painless method appears useful for experimental and diagnostic studies in low pressure areas of the peripheral circulation.

The frequency histogram—A new method for the evaluation of laser doppler flux motion

A digital filter system (DFS) was implemented to describe the frequency components of laser Doppler signals. The DFS calculates a frequency histogram on the basis of the prevalence of a certain frequency band during the sample period. This approach seems to be more suitable for the detection of low-power small-amplitude flux motion components recorded by laser Doppler as compared to the commonly used fast Fourier algorithm. Fourier analysis provides an amplitude-relevant frequency spectrum which may overlook relevant frequency components with small amplitude due to low power or short duration. DFS allows better detection of such signals as demonstrated by the initial clinical results of this study evaluating flux motion on the feet of 4 healthy controls and 10 patients with peripheral arterial occlusive disease. Three frequency components are easily distinguished corresponding to low (3.6 +/- 1.5 cycles/minute) and high (18.6 +/- 4.5 cycles/min) frequency flux motion and the pulsatile waves due to cardiac action.

A new therapeutic approach to popliteal artery entrapment syndrome (PAES)

OBJECTIVES An alternative therapeutic approach to popliteal artery entrapment syndrome (PAES) with vascular complications. MATERIALS Three male patients (16, 42 and 68 years) with thrombotic and/or embolic obstructions of popliteal or crural vessels as a consequence of popliteal entrapment syndrome. METHODS Combined catheter treatment consisting of percutaneous transluminal thrombembolectomy (PTEE), local thrombolysis (LTL) and percutaneous transluminal dilatation (PTA) was performed for thrombotic and embolic obstructions of popliteal or crural vessels. The aberrant tendomuscular structures were surgically corrected at a later date. RESULTS After the procedure systolic ankle/arm pressure ratios in the three patients improved from 0.66 to 1.13, 0.57 to 1.07 and 0.46 to 1.10. Twelve, 8 and 4 months later the patients were asymptomatic. None of the patients showed popliteal artery compression during plantar flexion on Duplex scanning. CONCLUSIONS This new therapeutic approach avoids direct vascular surgery with bypass or patch implantation in patients with PAES who are often young. The long term results remain to be evaluated.