Bengt Fagrell

The effects of light to moderate drinking on cardiovascular diseases.

3 Department of Family Preventive Medicine, UCSD, La Jolla, CA, USA; 4 Brigham and Womens Hospital, Boston, MA, USA; 5 Danish Epidemiology Science Center, Institute of Preventive Medicine, Kommunehospitalet, Copenhagen, Denmark; 6 Department of Community Health, University of Aukland, NZ; 7 Kaiser Permanente Medical Center, Oakland, CA, USA; 8 University of Kuopio, Kuopio, Finland; and 9 Royal Free and University College Medical School, London, UK

Local Microcirculation in Chronic Venous Incompetence and Leg Ulcers

Most chronic leg ulcers (90 to 95%) are caused by incompetence of the deep venous system and/or the perforators of the lower leg. Superficial venous incompetence does not give rise to necrotic skin ulcers. The primary cause of venous leg ulcers is the marked increase in pressure that builds up in the deep veins of the lower leg during walking. This pressure is transformed to the skin vessels through the ankle perforators, out to the nutritional vascular bed of the skin. The intracapillary pressure increases tremendously and this causes the capillaries to dilate and become tortuous. The blood elements leak out through the capillary wall into the surrounding tissue and form a specific microedema, which gives rise to an effective nutritional block between the capillaries and the skin cells. This microedema is most probably the main cause of the development of venous leg ulcers.

Relative hematocrit in human skin capillaries and its relation to capillary blood flow velocity.

Abstract Blood flow velocity (CBV) and relative hematocrit (Hct) in human nailfold capillaries were measured by noninvasive video-densitometric cross-correlation technique. Through a microscope a video recording was made of the flow of blood cells in the skin capillaries. Two small videophotometric windows were positioned along a monitored capillary. The velocity in the capillary was measured by continuously computing the delay-time to maximum cross-correlation between identical optical signals generated at the two windows by blood cells and plasma gaps. The relative hematocrit was deduced from continuous records of the video-densitometric output of one window. Relative calibration was accomplished by assigning zero hematocrit to the output of the window in the absence of red cells, and 100% to the maximum output recorded during a period of 5 min. More or less periodic fluctuations of CBV and relative Hct were found in most capillaries studied. The frequency of the fluctuations was in the order of 5 to 10 cycles per minute. The changes of flow were almost invariably accompanied by changes in hematocrit. In most instances changes in CBV preceded changes in Hct by one to several seconds. The normal vasomotion appears to cause a continuous change in the proportion between red cells and plasma until the diameter of the arteriole is so narrow that erythrocytes are mechanically prevented from passing into the capillary. Prior to complete closure of the arteriole there is sometimes a flow of plasma such that the capillary is empty of blood cells when flow stops. Adjacent capillaries seem to have the same major vasomotion pattern but individual variations are often seen.

MICROCIRCULATORY METHODS FOR THE CLINICAL ASSESSMENT OF HYPERTENSION, HYPOTENSION, AND ISCHEMIA

New techniques are now available for studying skin microcirculation non-invasively in humans. The clinically most useful ones are laser Doppler fluxmetry, vital capillaroscopy, dynamic capillaroscopy and fluorescence microscopy. Some of these techniques have now been used in clinical practise for studying the reactivity of the skin microcirculation in patients with hypertension, hypotension and ischemia. It was found that the reactivity to stress in patients with hypertension can be quite different in the skin microvascular bed as compared to the total circulation of the region. In patients with local hypotension due to an arterial obstruction the postocclusive reactive hyperemia response is significantly changed compared to normals. The vasomotion activity is also decreased in the low, pressure area. A marked decrease in the local blood pressure may lead to tissue ischemia. In these patients the risk of skin necrosis can be evaluated by microscopic classification of the structural changes of the capillaries in the area of ischemia. When the skin capillaries are void of erythrocytes the risk of necrosis is imminent.

Capillary Blood Cell Velocity in Full-Term Infants as Determined in Skin by Videophotometric Microscopy

ABSTRACT: In order to study the neonatal microcirculation, the capillary hemodynamics in skin was investigated in 43 full-term infants 2–7 days after birth. The nailfold capillaries of the thumb were visualized by means of television microscopy and the capillary blood cell velocity (CBV) was videophotometrically quantified in 107 microvessels. The skin temperature, mean arterial blood pressure, and heel puncture hematocrit were measured simultaneously to evaluate any relation with the CBV. The mean CBV in all infants was 0.38 ± 0.21 mm/s, with a range of 0.04 to 1.2 mm/s in individual capillaries. There was no correlation between CBV and skin temperature (27–33° C), mean arterial blood pressure (44–68 mm Hg), or postnatal age. However, a significant correlation was found between the log CBV and the skin prick hematocrit (r = −0.64, p < 0.001). It is concluded that the mean CBV during the 1st wk of life is not significantly different from the capillary velocity reported in adults. Normal variations in skin temperature and mean arterial blood pressure, as well as age differences 2–7 days after birth, do not significantly influence the neonatal skin capillary blood flow. However, the hematocrit is of major importance for skin capillary perfusion in the newborn infant.

Cardiovascular Reactions during Psychiatric Interview A Non-Invasive Study on a Twin Sample

A sample of 18 monozygotic and 13 dizygotic male twin pairs in the ages 51-74 (mean 62) was exposed to a stressful psychiatric interview. Genetic influence over blood pressure and peripheral pulse volume was observed to be most evident at the end of the interview, while heart rate was genetically strongly influenced both at rest and during the whole interview.

Skin microcirculation in neonatal polycythaemia and effects of haemodilution. Interaction between haematocrit, vasomotor activity and perfusion

The cutaneous microcirculation was investigated before and 2–4 h after haemodilution in 13 newborn infants with polycythaemia. Skin microvascular perfusion was related to the haematocrit and to the presence of rhythmical changes in blood flow, reflecting vasomotor activity. The microcirculation was studied with a laser Doppler fluxmeter in a superficial microvascular bed represented by the dorsal hand skin. In five subjects, it was possible to combine laser Doppler flux measurements with microscopic quantitations of blood cell velocity in single, nailfold capillaries. In neonates less than 12 h postnatal age (n= 6), microvascular perfusion was only one‐third that of the equally polycythaemic, but older infants (n= 7, p < 0.01). The higher perfusion in the older neonates with polycythaemia was associated with rhythmical variations in blood flow (3–5 cycles/min). There was no difference in skin temperature, blood pressure or heart rate between the two age groups. After haemodilution, the younger infants had developed rhythmical blood flow variations with the same characteristics as in the older group, in which the flow pattern was unchanged. In association, the laser Doppler flux had increased 304% in the younger and 73% in the older group (median values, p<0.05 versus pretreatment values). The post‐treatment change in laser Doppler flux corresponded to an increase in nailfold capillary blood cell velocity from 0.08 (0.02–0.23) mmjs prior to haemodilution to 0.21 (0.07–0.32) mmjs after treatment (n = 5, p < 0.05). Skin microcirculatory effects of neonatal polycythaemia and haemodilution vary in relation to vasomotor activity.

Effects of neonatal polycythemia and hemodilution on capillary perfusion

The effects of neonatal polycythemia on nutritive capillary perfusion were investigated by a television microscopy technique. The capillary blood flow velocity in skin was measured in 12 neonates with polycythemia before and after treatment with hemodilution, and in 13 healthy control infants. The capillary blood flow velocity in the patients was 0.11 (0.02 to 0.34) mm/sec and in the healthy control infants 0.30 (0.17 to 0.44) mm/sec ( p r =−0.98; p

Reactive hyperemia in term neonates and adults—A laser Doppler fluxmetry study of skin microcirculation

The reactivities of neonatal and adult microcirculation have been studied and compared. The cutaneous reactive hyperemia after 1 and 4 min of arterial occlusion (AO) was measured with a laser-Doppler fluxmeter in 21 healthy neonates and 10 adults. Local skin temperature, mean arterial blood pressure (MAP), and skin prick hematocrit were also determined at the same time. The magnitude of neonatal reactive hyperemia was approximately one-third that of the adult response regardless of the duration of AO. In both groups, with age-specific regressions, the hyperemic blood flow response after 4 min of AO developed more slowly in subjects with low MAP and was of low magnitude in subjects with high hematocrit values. In response to a prolongation of AO, from 1 to 4 min, the magnitude and duration of hyperemia increased significantly and similarly in both neonates and adults. We conclude that compared to adults neonates have a less pronounced ability to increase skin microcirculation in response to local ischemia. The normally low blood pressure and high hematocrit in newborn infants contribute further to this conclusion.

(D)-Penicillamine Treatment in Systemic Sclerosis (Scleroderma): Effect on Nutritional Capillary Circulation

Four patients with systemic sclerosis (scleroderma) were treated with (D)-penicillamine (1.2-1.8 g/d) for 18-60 months. All patients improved. Vital capillary microscopy demonstrated that the number of visible skin capillaries increased during therapy, thus indicating a more efficient nutritional circulation.