Laser Doppler flux measurement for the assessment of cutaneous microcirculatio--critical remarks.

Back scattered Laser Doppler (LD) signals are composed of two different individual signals. The number of the moving particles and the speed of the particles in the measured tissue volume determine the frequency shift and the band width of the Doppler signal. The dependence of the Laser Doppler flux on the number of scattering particles is highly nonlinear: at very low hematocrit and high speed the axial migration of the cells to the centre of the blood vessels is very strong, so that in these cases - because of the parabolic flow profile - the Doppler flux measurement overestimates the mean real blood flow (up to two- or three-fold). The opposite is the case when the hematocrit is very high, then the blood flow might be underestimated (due to the increased amounts of blood cells near the vessel wall). In addition, a very change in number of moving particles - as can occur during the postprandial phase or during therapy - can change the signal also at a constant cell number. Also, it must be mentioned that the LD signal possibly is not only reflected by moving blood cells in the different skin layers but also by blood cells flowing in tissues below the skin (particularly below atrophied skin areas of older patients) so that in such cases the LD Flux signal reflects not exclusively the skin blood flow. Therefore, LD flux at rest may still be within the normal range even in advanced states of disease, since the scattered light is sampled from a tissue volume which may contain also non-nutritive shunt vessels. This critical analysis of the LD signals of course shall not lead to an overall rejection of the application of laser Doppler systems. Actual progress only can, however, be obtained under the exact consideration of anatomical conditions, technical restrictions and when generalizations are avoided.

Microcirculation in hypertensive patients.

Regardless of the mechanisms that initiate the increase in blood pressure, functional and structural changes in the systemic vasculature are the final result of long-standing hypertension. These changes can occur in the macro- but also in the microvasculature. The supply of the tissues with oxygen, nutrients, and metabolites occurs almost exclusively in the microcirculation (which comprises resistance arterioles, capillaries and venules), and an adequate perfusion via the microcirculatory network is essential for the integrity of tissue and organ function. This review focuses on results from clinical studies in hypertensive patients, which have been performed in close cooperation with different clinical groups over the last three decades. Intravital microscopy was used to study skin microcirculation, microcatheters for the analysis of skeletal muscle microcirculation, the slit lamp for conjunctival microcirculation and the laser scanning ophthalmoscope for the measurement of the retinal capillary network. The first changes of the normal microcirculation can be found in about 93% of patients with essential hypertension, long before organ dysfunctions become clinically manifest. The earliest disorders were found in skin capillaries and thereafter in the retina and the skeletal muscle. In general, the disorders in the different areas were clearly correlated. While capillary rarefaction occurred mainly in the retina and the conjunctiva bulbi, in skin capillaries morphological changes were rare. A significant decrease of capillary erythrocyte velocities under resting conditions together with a marked damping of the postischemic hyperemia was found, both correlating with the duration of hypertension or WHO stage or the fundus hypertonicus stage. Also the mean oxygen tension in the skeletal muscle was correlated with the state of the disease. These data show that the microcirculatory disorders in hypertension are systemic and are hallmarks of the long-term complications of hypertension. There is now a large body of evidence that microvascular changes occur very early and may be important in their pathogenesis and progression.

Influence of acetylsalicylic acid (Aspirin) on cutaneous microcirculation.

BACKGROUND: The protective effect of acetylsalicylic acid (aspirin) in primary and secondary prophylaxis of cardiovascular events is attributed to the inhibition of platelet cyclooxygenase (COX). However, a recent animal study found a vasodilating and blood pressure lowering effect of aspirin independent of COX, but mediated by inhibition of the RhoA/Rho kinase signaling pathway. METHOD: Prospective, randomized, double-blind, placebo-controlled cross-over study. In each instance 5 healthy volunteers received either aspirin 500 mg/d or placebo for 7 days. Capillary red blood cell velocity (vRBC) at rest and after postischemic hyperemia was determined on day 1 and 7 by means of nailfold capillary microscopy. RESULTS: In the aspirin group after 7 days a significant increase of vRBC was found at rest and during hyperemia. In the placebo group vRBC did not change. The finding was confirmed by the cross-over design of the study. CONCLUSION: Aspirin at a dosage of 500 mg/d has an impact on vasoregulation in the microcirculation. At present, the underlying mode of action in humans is unknown.

Correlation between postischemic vasodilation of the arteria brachialis and of the postischemic hyperemia in the adjacent microvascular bed.

BACKGROUND: Endothelial cells secrete different mediators depending on biochemical and/or biophysical conditions, which can lead to vasodilation or vasoconstriction, respectively. Impaired endothelial responsiveness to specific vasodilator stimuli has been used as a surrogate marker of cardiovascular risk. Multiple methods allow testing endothelial responses in both microvessels and conduit arteries, but it is still unclear whether there is a relationship in endothelial function between these two different vascular beds. MATERIAL AND METHODS: In order to examine, whether such macrocirculatory data might correlate with data obtained in the supplied microvessels, a parallel investigation in the brachial artery (BA) and the supplied nailfold capillaries was performed. The duration and amplitude of the postischemic hyperemia (stasis in the vasculature of the left arm using a blood pressure cuff for 3 minutes) were measured (ultrasound technique) and simultaneously the amplitude and duration of the postischemic hyperemia in ipsilateral nailfold capillaries (intravital capillaroscopy). RESULTS: There was absolutely no correlation between the duration (n = 153, r = 0.076, p = 0.3493) of the diameter increase in the BA and in ipsilateral nailfold capillaries. CONCLUSION: The regulation of the cutaneous microcirculation did not follow diameter changes of the conduit artery (BA) but seems to be dominated by the precapillary arterioles.

[Persistent left atrial thrombus in atrial fibrillation under oral anticoagulation]. / Persistierender linksatrialer Thrombus bei Vorhofflimmern unter oraler Antikoagulation.

The case of a 78-year-old female patient who suffered atrial fibrillation and persistent thrombus in the left atrial appendage despite sufficient anticoagulation is reported. The case is chosen to demonstrate the complexity inherent in prophylaxis as well as risk evaluation of thromboembolism on the basis of clinical and echocardiographic criteria. We also discuss transesophageal echocardiography as the standard diagnostic procedure for detection of intracardiac thrombi prior to cardioversion as well as cardiac computer tomography as an alternative.

Capillary bleeding under oral anticoagulation.

BACKGROUND: Oral anticoagulants are routinely used for prevention of thromboembolism in cardiac, arterial or venous diseases. Hemorrhages are serious treatment complications, frequently occurring under long-term and/or high-dose regiments. From animal experiments it is known that coumarin-type anticoagulants may cause capillary dilatation and increased permeability, red blood cell extravasation and punctate bleeding. Controlled human trials are lacking. METHODS: 31 patients under oral anticoagulation were examined by video capillary microscopy. 52 patients with comparable diseases and treatment but without oral anticoagulation served as controls. Nailfold capillaries of four fingers of each hand were examined and analyzed off-line according to the following criteria: (1) numbers of capillaries investigated, (2) numbers of capillary bleedings, and (3) bleeding incidence (bleedings per 100 capillaries). RESULTS: In 23 out of 31 patients (74.2%) capillary bleedings were observed. The bleeding incidence ranged from 0.33 to 4.29 per 100 capillaries. In contrast, only 4 out of 52 controls were detected with capillary bleedings (2.1%, p<0.001). The bleeding incidence was 0.34-2.41. In patients on anticoagulation there was no correlation between the number of capillary bleedings and the INR or Quick values. During a two year follow-up of patients on oral anticoagulation no significant difference was found in terms of clinically obvious bleedings in patients with or without capillary bleedings. CONCLUSION: This study shows that capillary bleedings can be demonstrated in patients on oral anticoagulation. Bleedings occur independent of the INR-value. Thus, other factors than the vitamin-k-dependent coagulation effect seem to be causal for the damage of microvessels. Further, the evidence of capillary bleedings is not a prognostic indicator for future hemorrhage.

Endovascular treatment of an occluded popliteal aneurysm with locoregional thrombolysis followed by stent graft exclusion.

Popliteal artery aneurysms can thrombose or cause distal embolization and are therefore potentially limb-threatening lesions. This report describes the case of a 70-year-old man with severe claudication due to a thrombosed aneurysm of the left popliteal artery. He gave consent for a locoregional thrombolytical therapy, but refused standard surgical treatment. Thus, we developed the idea to restore blood flow by means of thrombolysis first, and then to perform a definitive repair of the aneurysm after a period of time. After successful thrombolysis and after 14 days as an outpatient with weight adjusted subcutaneous heparin and daily exercise, the man was free of symptoms. An endovascular repair with a Hemobahn stentgraft was performed. At the end, the procedure was successfull. This stepwise endovascular approach can change an acute into an elective situation and positively influence long-term results.

Dobutamine stress magnetocardiography for the detection of significant coronary artery stenoses - a prospective study in comparison with simultaneous 12-lead electrocardiography.

BACKGROUND: Exercise electrocardiography is an imperfect test for the detection of coronary artery disease (CAD). Magnetocardiography detects cardiac electrical disturbances associated with myocardial ischemia. We prospectively investigated the accuracy of high-dose dobutamine stress magnetocardiography (DS-MCG) and simultaneous electrocardiography (DS-ECG) for the detection of significant CAD. METHODS: 100 patients with an intermediate pre-test probability for CAD underwent DS-MCG using a multichannel magnetometer prior to invasive coronary angiography. Patients were examined at rest and during a standard dobutamine-atropine scheme. Significant reduction of epicardial current strength/density during stress, reconstructed from the magnetic field map and superposed on a virtual heart model indicates myocardial ischemia. A 12-lead DS-ECG was recorded simultaneously. Significant coronary artery stenosis was defined as > or = 70% of lumen reduction. RESULTS: Without beta-blocker all 100 patients reached the targeted heart rate. The image quality of DS-MCG and DS-ECG was sufficient for analysis in all patients. In 19 patients CAD was ruled out angiographically. Thirty two or seven patients revealed coronary artery stenoses of 30-49% or of 50-69%, respectively. In 42 patients we found significant stenoses of > or = 70%. In 41 of these patients DS-MCG revealed myocardial ischemia. The sensitivity of DS-MCG and DS-ECG for the detection of significant coronary artery stenosis was 97.6% and 26.2%, the specificity of DS-MCG and DS-ECG 82.8% and 82.8%, respectively. CONCLUSIONS: DS-MCG can be performed with a standard dobutamine/atropine stress protocol. DS-MCG yields a significantly higher accuracy for the detection of significant coronary artery stenosis than DS-ECG.

Influence of xantinole nicotinic acid on cutaneous microcirculation in patients with coronary artery disease and hyperlipoproteinemia.

Xantinole nicotinic acid (NA) dose dependently lowers plasma levels of atherogenic lipoproteins and increases blood flow through vasodilation. The aim of this study was to evaluate the effect of NA on cutaneous microcirculation in patients with coronary artery disease and hyperlipidemia. In this open pilot study, five men and three women (74.2+/-9.1 yrs; 81.4+/-7.9 kg; 171.6+/-7.0 cm) with angiographically proven coronary artery disease and hyperlipidemia were included. Nailfold capillary microscopy was used for measurements of erythrocyte velocities at rest and after three minutes of ischemia, before and one hour after intake of 1000 mg of NA. The blood pressure (120+/-12/73+/-8 mmHg vs. 113+/-10/72+/-5 mmHg; p=0.19/0.83) and the heart rate (72+/-8/min vs. 70+/-7/min; p=0.38) remained unchanged. The mean capillary red blood cell velocity at rest (v(RBC); 0.27+/-0.23 mm/s vs. 0.32+/-0.18 mm/s; p=0.089) and the time to maximal post ischemia erythrocyte velocity (t(peak); 21.0+/-7.9 s vs. 24.3+/-15.5 s; p=0.49) did not change. The maximal post ischemic erythrocyte velocity (v(maxRBC); 0.93+/-0.33 mm/s vs. 1.19+/-0.19 mm/s; p=0.0096) raised slightly but significantly, the duration of post-ischemia hyperemia (DpH; 101+/-16 s vs. 127+/-15 s; p=0.0005) increased markedly. One patient reported about flush in the whole body. The administration of 1000 mg of NA resulted in a significant improvement of the cutaneous microcirculation in patients with coronary artery disease and hyperlipidemia.

Effects of desmopressin on platelet membrane glycoproteins and platelet aggregation in volunteers on clopidogrel.

PURPOSE: The use of clopidogrel is standard in interventional cardiology. Haemorrhage occurs in some patients, which implies a need for a non-transfusional therapy. Desmopressin showed its efficacy as an antidote of acetylsalicylic acid. In this trial the effects of desmopressin on platelet glycoproteins and the platelet's ability to aggregate under the influence of clopidogrel are studied. METHODS: The trial was conducted as an open, prospective, single-centre, randomised pilot study with n=17 healthy volunteers in a parallel-group design. 1 h after an oral loading dose of 375 mg clopidogrel the effects of a single-dose of 300 mug of Octostim nasal spray (n=9) on platelet aggregation, activity of platelets on the density of membrane-bound receptors are measured. RESULTS: Ristocetin cofactor and platelet reactivity rose significantly after the administration of Octostim nasal spray with 31.9% and 5.3%, respectively (p=0.0329; p=0.0414). The ADP-induced platelet aggregation increased after the administration of Octostim nasal spray by approximately 20% (p=0.0564). The fraction of CD62- and CD63-positive platelets did not change after clopidogrel nor after desmopressin (p=0.4203; p=0.6774). The density of GPIIb/IIIa receptors per platelet did not change after desmopressin (p=0.9652). The density of GPIb/IX receptors per platelet rose after desmopressin without reaching the level of significance (p=0.0802). In the desmopressin group alone the receptor density rose by 5.5% (p=0.0783). CONCLUSION: The administration of desmopressin improved the primary haemostasis when given in addition to a clopidogrel therapy. Patients undergoing a heart catheter procedure with clopidogrel might benefit from the use of desmopressin when having a bleeding episode.

Sublingual application of liquid nitrendipine does not result in critical hypotension in healthy volunteers under phosphodiesterase-5 inhibition.

INTRODUCTION: The introduction of phosphodiesterase-5 inhibitors as sildenafil, tadalafil, or vardenafil, has tremendously improved the treatment of erectile dysfunction. Patients with the common comorbidity of cardiovascular disease and erectile dysfunction, however, are at risk for critical hypotension in case of self-treatment of cardiac angina with nitrates after the intake of a phosphodiesterase-5 inhibitor. METHODS: We evaluated the safety of 5 mg sublingual nitrendipine after pre-treatment of 8 healthy male volunteers (42.1+/-9.6 yrs) with 20 mg tadalafil. Randomly four different protocols were compared using six hours blood pressure recordings: (1) baseline, (2) 20 mg tadalafil, (3) 5 mg nitrendipine, and (4) 20 mg tadalafil+5 mg nitrendipine. RESULTS: The blood pressure was not significantly affected by tadalafil. Nitrendipine lowered the systolic blood pressure significantly by -1.91 mmHg (p=0.0079). The co-medication of 20 mg tadalafil+5 mg nitrendipine lowered the blood pressure significantly by -2.86 mmHg (p<0.0001). There was no statistically significant difference between tadalafil and nitrendipine (p=0.598). Relevant hypotension (systolic blood pressure of <85 mmHg) was observed in none of the study individuals during the four protocols. CONCLUSIONS: Sublingual nitrendipine seems to be safe for self-treatment of an anginal attack in patients with stable coronary artery disease, who have taken a phosphodiesterase-5 inhibitor. However, our findings on hemodynamic changes in apparently healthy volunteers have to be confirmed in patients with coronary artery disease.

Cutaneous microcirculatory function predicts the responsiveness to tadalafil in patients with erectile dysfunction and coronary artery disease.

Despite the proven clinical efficacy of phosphodiesterase inhibitors in the treatment of erectile dysfunction (ED), some patients do not respond to the medication. By means of nailfold capillary microscopy in patients with concomitant coronary artery disease (CAD) and ED, it was evaluated whether the extent of microvascular dysregulation predicts the responsiveness to tadalafil (TAD) in terms of erectile function. The ED of each patient was assessed by the International Index of Erectile Function (IIEF). Patients presenting both, documented CAD and ED, showed a significantly reduced capillary red blood cell velocity (v(RBC)) at rest and after 3 min of ischemia compared with age-matched controls. At 2 h after intake of 20 mg of TAD, a significant increase of v(RBC) at rest as well as during postischemic hyperemia was found. Patients who reported no improvement of their ED after the use of TAD demonstrated no changes in the duration of postischemic (DpH) hyperemia, or even a reduction of the DpH. The majority of the patients, who reported at least one successful sexual intercourse due to TAD, had a prolongation of DpH. We conclude that assessment of microvascular regulation by nailfold capillary microscopy can predict the probability of a treatment failure with phosphodiesterase inhibitors in patients with ED. Moreover, as endothelial dysfunction is the common underlying pathophysiological process of ED and cardiovascular diseases, the test may help to identify patients at risk for the development of atherosclerosis and following cardiovascular events.

[Cardio-pulmonary vascular system. Three-dimensional quantitative evaluation by microcomputed tomography]. / Kardiopulmonales Gefässsystem. Dreidimensionale quantitative Evaluation mit der Mikrocomputertomographie.

In recent years microcomputed tomography (microCT) has become more and more important in basic research. Now commercial microCT scanners are available. Thus, it is very likely that this new, accurate and promising method for three-dimensional and non-destructive quantitative evaluation of intact tissues including vessels will be applied more frequently. The review provides a survey of the basic technology of microCT and its current use for high resolution three-dimensional morphometric and functional analysis within the cardio-pulmonary vascular system.

Genome sequence of Halobacterium species NRC-1.

We report the complete sequence of an extreme halophile, Halobacterium sp. NRC-1, harboring a dynamic 2,571,010-bp genome containing 91 insertion sequences representing 12 families and organized into a large chromosome and 2 related minichromosomes. The Halobacterium NRC-1 genome codes for 2,630 predicted proteins, 36% of which are unrelated to any previously reported. Analysis of the genome sequence shows the presence of pathways for uptake and utilization of amino acids, active sodium-proton antiporter and potassium uptake systems, sophisticated photosensory and signal transduction pathways, and DNA replication, transcription, and translation systems resembling more complex eukaryotic organisms. Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria. The ease of culturing Halobacterium and the availability of methods for its genetic manipulation in the laboratory, including construction of gene knockouts and replacements, indicate this halophile can serve as an excellent model system among the archaea.

Influence of antithrombin III on coagulation and inflammation in porcine septic shock.

The physiological inhibitor of thrombin, antithrombin III (ATIII, Kybernin P) was investigated for its antiinflammatory and anticoagulant effects in a pig model of septic shock. Pigs were infused with a dose of 0.25 microgram. kg-1. h-1 of lipopolysaccharide (LPS) over a period of 3 hours. Animals developed systemic inflammation, disseminated intravascular coagulation (DIC), organ failure and cardiovascular abnormalities, namely pulmonary hypertension and systemic hypotension. Twenty septic pigs were allocated to 2 study groups, treated either with ATIII (n=10) or placebo (n=10). ATIII was administered as a 250-U/kg IV bolus infusion for 30 minutes (-60 to -30 minutes) followed by a single IV bolus of 125 U/kg (t=0) and a second 30-minute infusion of 250 U/kg (120 to 150 minutes). ATIII significantly prevented the development of a DIC; the increase in fibrin monomers (placebo, 11.4+/-9.1 reciprocal titers, at 6 hours) was completely overcome by ATIII (P<0. 05). ATIII significantly prevented the increase in thromboxane (TXB2) levels, which were 809+/-287 pg/mL in the placebo and 420+/-174 pg/mL in the verum group after 6 hours (P<0.02). On the other hand, ATIII had no influence on TNF levels. In a lethal study with an increased dose of LPS (0.5 microgram. kg-1. h-1). A significant reduction in mortality was observed in the ATIII group (0 of 7) compared with the placebo group (4 of 6) (P<0.05, chi2 test) a significant reduction of pulmonary hypertension (placebo, 42.0+/-11. 1 mm Hg; ATIII, 23.6+/-7.5 mm Hg, P<0.05), but no effect on systemic hypotension, was noted in the ATIII group. It was thus concluded that modulation of the procoagulatory state by substitution of ATIII results in a late beneficial antiinflammatory effect in this model of septic shock.

[Microcirculation and hemostasis in inflammatory processes. Modulation by administration of physiologic protease inhibitors as a therapeutic approach]. / Mikrozirkulation und Hämostase bei entzündlichen Prozessen. Modulation durch den Einsatz physiologischer Protease-Inhibitoren als therapeutischer Ansatz.

BACKGROUND: The course of an inflammatory process is based upon complex interactions between the vessel wall and the humoral or cellular compounds of the vascular content as a consequence of a defense reaction. There are no substantial differences between the pathophysiology of local or of whole body inflammation on the molecular and cellular level. Sepsis, which is clinically regarded as a systemic inflammatory process requires the broad therapeutical spectrum of nowaday intensive care medicine, but still has a high mortality. The pathophysiology and clinical examples for both systemic and local inflammatory reactions are presented in this paper. Thereby, similar interactions between the vascular endothelium, the mediator systems to which the hemostatic system has to be considered as a part of, and the microcirculation remain in the foreground at first. Based on that, the use of polyvalent protease inhibitors in the therapy of local or systemic inflammatory reactions of different origin will be discussed. The spotlight falls on physiological inhibitors of the hemostatic and complement system, antithrombin III and C1-esterase inhibitor, which may have a regulatory function within these systems because of their multiple targets. CONCLUSION: The possibility of an adjuvant therapy of local or generalized inflammatory processes with physiologic protease inhibitors seems to be very promising. Nevertheless, at yet the substantial mechanisms of action are not fully understood.

Hemostatic abnormalities and the severity of illness in patients at the onset of clinically defined sepsis. Possible indication of the degree of endothelial cell activation?

OBJECTIVE: To find out whether changes within the hemostatic system are related to the severity of illness and organ failure in patients at the onset of clinically defined sepsis and to find some indications for the contribution of endothelial cell activation or perturbation to the patient's status. The following measurements were undertaken: Acute Physiology and Chronic Health Evaluation (APACHE) II score, multiple organ failure (MOF) score, plasma levels of thrombin-antithrombin III complexes (TAT), antithrombin III (AT III), protein C antigen, factor XII, and plasminogen activator inhibitor type 1 antigen (PAI-1), neopterin, and interleukin 6 (IL-6). DESIGN: A prospective case series study. SETTING: Intensive care unit (ICU) of the Department of Internal Medicine, Justus Liebig University, Giessen, Germany. PATIENTS: 28 consecutive patients (11 females, 17 males; mean age 58 years) with clinically defined sepsis. Eleven patients were admitted from the surgical ICU (9 after elective surgery, 2 after trauma surgery). The operations were done 1-26 days (mean 14 days) prior to the onset of sepsis. MAIN RESULTS: At the onset of sepsis we found elevated plasma levels of TAT, PAI-1, neopterin, and IL-6, and lowered plasma levels of AT III, factor XII, and protein Cantigen. Neopterin, PAI-1, IL-6, and factor XII showed a statistically significant correlation with the APACHE II score. The MOF score is significantly correlated with IL-6 and neopterin. The extent of hemostatic abnormalities was related to increasing levels of IL-6. CONCLUSIONS: Clinical evidence of a septic process is most likely to be preceded by activation of the hemostatic system, the vascular endothelium, and the monocyte/macrophage system. IL-6 may have a regulatory function for hemostasis in inflammation. Laboratory monitoring could be helpful in deciding whether to start early intensive therapy in patients at risk for sepsis.