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PubMed2002

Alterations to hepatic microcirculation in thioacetamide-induced cirrhotic livers of rats.

In liver cirrhosis, increased resistance of intrahepatic microvasculature contribute to the development of portal hypertension. This study aimed to reveal the alterations to hemodynamics in microvasculature of thioacetamide-induced fibrotic and cirrhotic rat livers, using in vivo microscopy. In fibrotic livers, although intrahepatic blood flow remained unaltered, area percentage of sinusoids was significantly decreased. In cirrhotic livers, intrahepatic blood flow was significantly increased concurrently with decrease in area percentage of sinusoids. The flow velocity and volume flow were significantly increased in terminal portal venules (TPVs) without changes in vascular diameters, whereas all these parameters were not altered in terminal hepatic venules (THVs). Intrahepatic shunts which emerged from TPVs and ran toward THVs, and anastomoses between neighboring THVs were formed in cirrhotic livers. These data indicate that the first occurring alteration of microcirculation in liver cirrhosis is decrease in sinusoidal beds.

Animals↗

PubMed2002

Hemorheology and expression of neutrophil adhesion molecules CD18 and CD62L in pancreatic microcirculation of Caerulein induced experimental acute pancreatitis.

OBJECTIVE: To explore the changes in hemorheology and expression of neutrophil adhesion molecules CD18 and CD62L in pancreatic microcirculation of Caerulein induced experimental acute pancreatitis (AP). METHODS: The Wistar rats (n = 21) were randomized into three groups. The model of AP was established by subcutaneous injection of Caerulein. The changes of apparent viscosity of whole blood were measured by Low- shear 30 rheometer. The expression of adhesion molecules on the surface of neutrophil in duced by shear stress was used with stationary control. CD18 expression was increased on neutrophils treated with shear rate, and andanalyzed using flow cytometry. RESULTS: Rat treated with Caerulein showed hyperamyleimia (t = 69.029, t = 79.734, P < 0.05). Blood viscosity of two AP groups were significantly elevated (0.512 s(-1): t = 10.725, t = 16.945; 5.96 s(-1): t = 12.781, t = 11.992, P < 0.05). Compared with stationary control, CD18 expression was increased on neutrophil treated with shear rate, and significantly induced with shear rate >/= 94.5 s(-1) (94.5 s(-1): t = 7.403, t = 13.323, t = 16.655; 128.5 s(-1): t = 10.092, t = 28.531, t = 24.563, P < 0.05). The expression of CD62L was less sensitive to low shear rate, and began to be down-regulated significantly when the shear rate >/= 94.5 s(-1) (94.5 s(-1): t = 10.687, t = 19.376, t = 12.848; 128.5 s(-1): t = 26.152, t = 48.402, t = 56.814, P < 0.05). CONCLUSIONS: The changes of apparent viscosity of whole blood, and the effect of fluid shear stress on the expression of neutrophil adhesion molecules CD18, CD62L may play an important role in the pancreatic microcirculatory failure of acute pancreatitis.

Acute Disease↗

PubMed2002

Myocardial infarction temporally related to ephedra--a possible role for the coronary microcirculation.

Myocardial infarction has been reported with ephedrine and pseudoephedrine use. It has been suggested that these agents may induce coronary artery spasm, hypercoagulable states, or oxygen demand imbalance. We report a 25-year-old male with myocardial infarction after receiving a diet pill containing ephedra. Coronary angiography revealed normal coronary arteries with very slow flow, suggestive of microcirculation abnormalities. The flow responded promptly to intracoronary verapamil.

Adult↗

PubMed2002

[Microcirculation in patients with chronic gastritis depending on its exacerbation severity and morphological type].

The study of microvasculature in bioptic specimens of gastric mucosa and of conjunctival microcirculation from 254 patients with chronic gastritis revealed that exacerbation of the disease proceeds with severe disorders of terminal blood flow which are typical for the chronic relapse trombohemorrhagic syndrome and have generalized character. The microvascular disorders is manifested by plasma- and hemorrhages, by microvascular spasm and dilatation, intravascular hemostasis and microthrombosis. These manifestations were more expressed over the period of bright marked exacerbation of the disease and in patients with erosive affection of gastric mucosa.

Adult↗

PubMed2000

[A biomechanical model of local control of microcirculation].

In this paper we analyze the generation and motion of vasoactive metabolites in interstitium, the open and closure of precapillary sphincters, the factors affecting mean arteriolar diameter, and the change of amplitude of arteriolar vasomotion. A biomechanical model of local control of microcirculation has been developed. It is useful in quantitative analysis of microcirculatory local control.

Biomechanical Phenomena↗

PubMed2003

[Is blood squeezed out from the microcirculation soon after coronary occlusion?: real time myocardial contrast echocardiographic study].

BACKGROUND AND OBJECTIVES: The fate of blood trapped inside the myocardial microvessels after complete occlusion of the coronary artery has not been elucidated. Blood may be squeezed out by residual contraction even after coronary occlusion. The microcirculation was examined soon after coronary occlusion by real-time contrast echocardiography. METHODS: Myocardial opacification in the short-axis view was examined during infusion of FS69 (Optison) using the Coherent Contrast Imaging method(SIEMENS Sequoia 512) in 17 open chest dogs. The left circumflex coronary artery was completely ligated for 15 sec and the video intensity (256 gray level) of the risk area was measured at end-systole of every 3 beats before and after ligation. Temporal deterioration of the wall motion was evaluated, defined as normokinesis, mild hypokinesis and severe hypokinesis, and akinesis. Changes in the video intensity during each stage of wall motion abnormalities were examined. RESULTS: The video intensity of the risk area decreased significantly after coronary occlusion. Wall motion of the risk area deteriorated gradually after ligation, in which mild hypokinesis, severe hypokinesis and akinesis developed consecutively at 2.8 +/- 0.5, 5.4 +/- 0.5 and 7.8 +/- 0.8 sec after coronary ligation, respectively. The changes in video intensity during each stage of the wall motion abnormalities were small and not statistically significant, irrespective of severity of wall motion abnormalities. CONCLUSIONS: These findings suggest that the blood remains in the vascular bed immediately after the coronary occlusion and is not squeezed out even if wall motion of the risk area continues.

Animals↗

PubMed2000

Influence of gravity on flow distribution of red blood cells in microcirculation.

The influence of the gravity on flow distribution of erythrocytes in microcirculation was examined. We developed a new centrifuge system with a rotation disc. An observation system of blood flow in a micro-flow channel was arranged on the disc. Erythrocyte flow in the micro-flow tube was displaced under the gravity. This study suggests that the gravity affects the transfer of substances from blood vessels to tissues.

Centrifugation↗

PubMed2002

Coronary microcirculation and reperfusion failure. Do we know what diagnostic tools we have?

Almost one in five patient has reperfusion abnormalities despite the type of percutaneous interventional procedure after acute myocardial infarction. It has been shown with myocardial contrast echocardiographic and coronary angiographic studies that infarct related artery patency does not always correlate with the presence of adequate myocardial perfusion in the infarct related artery territory. Therefore, it is necessary to obtain further diagnostic and evaluation tools to assess coronary microcirculation and reperfusion failure. ST segment resolution time, TIMI flow grade, TIMI Frame Count and TIMI Myocardial Perfusion Grade (blush score) are helpful tools to assess myocardial perfusion and diagnosis of reperfusion abnormalities.

Humans↗

PubMed2003

Vascular function of forearm microcirculation in postmenopausal women with type 2 diabetes: potential benefit of hormone replacement therapy?

OBJECTIVE: To study the potential effects of hormone replacement therapy (HRT) on vascular function of the peripheral circulation in postmenopausal women with type 2 diabetes. METHODS: Seventeen premenopausal women aged 47.4 +/- 4.4 years (PreM), 23 nondiabetic postmenopausal women aged 59.4 +/- 7.0 years (PM), 15 postmenopausal women with type 2 diabetes aged 60.3 +/- 7.2 years (PMD) and 12 postmenopausal women with type 2 diabetes using HRT aged 61.2 +/- 4.0 years (PMDHRT) were studied. Vascular function of the peripheral circulation was investigated by measuring hyperemic responses of the forearm microcirculation following an ischemic stimulus using venous occlusion, strain-gauge plethysmography. Fasting lipids, glucose and glycated hemoglobin (HbA1c) were also measured. RESULTS: Forearm vascular function was significantly impaired in the PMD group: maximal blood flow (ml/100 ml/min) was 15.23 +/- 8.19 vs. 28.21 +/- 12.30 (PreM), 23.62 +/- 6.62 (PM) and 23.37 +/- 5.78 (PMDHRT) (p = 0.004); flow debt (ml/100 ml) was 3.99 +/- 2.83 vs. 7.40 +/- 4.92 (PreM), 5.66 +/- 3.67 (PM) and 8.57 +/- 4.84 (PMDHRT) (p = 0.0018); vascular resistance (mmHg/ml/100 ml/min) was 11.90 +/- 9.02 vs. 5.04 +/- 2.41 (PreM), 5.55 +/- 2.69 (PM) and 5.96 +/- 1.88 (PMDHRT) (p = 0.003). Fasting lipids, HbA1c and body mass index were not significantly different between the two diabetic groups. CONCLUSIONS: Postmenopausal women with diabetes have abnormal vascular function of resistance arteries that may improve with HRT. HRT may therefore reduce cardiovascular risk in postmenopausal women with type 2 diabetes, and a clinical end-point trial is warranted to test this hypothesis.

Adult↗

PubMed2001

[Impact of WPY on pancreatic microcirculation of acute pancreatitis in mice].

OBJECTIVE: To explore the pathogenesis of acute pancreatitis (AP) and evaluate the effect of a Chinese herb WPY on the course of AP. METHODS: Intravital fluorescence microscopy was used. The pancreatic microvascular diameter, RBC velocities and functional capillary density (FCD) were estimated following intracutaneous injection of caerulein alone or with gastropipe WPY. RESULTS: Caerulein mediated a significant decrease in functional capillary density (FCD), RBC velocities and diameter of interlobular arteriole (P < 0.01). Compared with AP group, WPY was effective in restoring functional capillary density, interlobular arteriole diameter and RBC velocity. CONCLUSION: Impairment of pancreatic microcirculation in the early phase of acute pancreatitis may play a key role in the progression of this disease. Possible contributory mechanisms include reduced blood flow and functional capillary density, interlobular arteriole spasm, and leukocyte-endothelial cell interaction. WPY has a beneficial effect on the course of acute pancreatitis. Possible causes include attenuating microcirculatory failure.

Acute Disease↗

PubMed2003

[New pathogenetic mechanisms of idiopathic dilated cardiomyopathy: changes in coronary microcirculation].

There is growing evidence of the presence and relevance of coronary microvascular abnormalities in many cardiac diseases. In particular, it has been recently shown that dilated cardiomyopathy is characterized by coronary microvascular dysfunction since its early onset. Abnormal coronary microcirculatory function is not an effect of myocardial damage but in turn seems to be able to cause progressive contractile dysfunction, ventricular dilatation and heart failure. The mechanisms are largely unknown but both myocardial hypoperfusion and myocardial ischaemia are most probably involved. It has been demonstrated that in patients with dilated cardiomyopathy the presence of severe coronary microcirculatory dysfunction is an independent and relevant prognostic factor. From these studies it is more and more evident that coronary microvascular dysfunction is a new pathogenetic mechanism in dilated cardiomyopathy and that the coronary microcirculation should be considered a new target of treatment in cardiac diseases at risk to evolve towards heart failure.

Cardiomyopathy, Dilated↗

PubMed2003

[Microcirculation of the small intestines in local and generalized circulatory disorders].

INTRODUCTION: Microcirculatory disturbances are known to affect the integrity of the gastrointestinal barrier. In our experiments, we aimed at characterizing the intramural microcirculatory reactions in response to various circulatory disorders using intravital microscopy with orthogonal spectral imaging technique. For the analysis and comparison of the microcirculatory reactions in the intestinal ileal mucosa, longitudinal muscle and Peyer's patches, a novel mathematical formula was established. METHODS: The microcirculatory consequences of mesenteric artery occlusion, endotoxemia, hemorrhagic shock and nitric oxide synthesis inhibition were characterized. RESULTS: During reperfusion, red blood cell velocity (RBCV) decreased by approx. 20% in all layers which persisted by end of the observation. In response to endotoxin, microcirculation of the muscle was more affected than that of the mucosa. In the hypovolemic phase of hemorrhagic shock and the late phase of resuscitation, a characteristic oscillatory flow pattern appeared in the villi and the weighed arithmetic average of RBCV decreased by 50%. NO synthesis inhibition caused an approx. 40% fall in RBCV in all layers and a spatial heterogeneity in the villi. CONCLUSION: Systemic circulatory disorders are characterized by a non-uniform microcirculatory failure and a redistribution of blood flow between the different layers favouring the mucosa. Using the suggested mathematical formula, the microcirculatory alterations can be characterized and compared.

Animals↗

PubMed1992

The effect of somatostatin, gabexate mesilate and dextran 40 on the microcirculation in sodium taurocholate-induced pancreatitis.

In vivo microscopy was performed to assess the effect of dextran 40, gabexate mesilate and somatostatin on the microcirculation in sodium taurocholate-induced pancreatitis in rats. Intraductal infusion of 0.4 ml of a 4% solution of sodium taurocholate decreased capillary blood flow, induced capillary stasis and increased vascular permeability in the head of the pancreas. Dextran 40, gabexate mesilate and somatostatin improved capillary blood flow in the initial phase of acute pancreatitis significantly and prevented stasis in 5 of 9, 3 of 8 and 7 of 10 (p < 0.05) cases. Only dextran 40 reduced the increase of vascular permeability. Decrease of capillary blood flow, capillary stasis and vascular permeability changes are important factors contributing to the pathogenesis of sodium taurocholate-induced pancreatitis. Dextran 40, gabexate mesilate and somatostatin exert a beneficial effect on the microcirculatory changes in this model of acute pancreatitis.

Animals↗

PubMed2003

Preservation of myocardial microcirculation during mechanical reperfusion for myocardial ischemia with either abciximab or eptifibatide.

Myocardial Blush Grade (MBG) is an angiographic method of assessing myocardial microcirculation and provides independent risk stratification among patients with normal TIMI 3 flow. Although the beneficial effect of abciximab on microvascular perfusion is well established, the efficacy of eptifibatide in the prevention of platelet aggregation and distal microembolization is less proven. After a pharmacologic shift by our institution towards the use of eptifibatide in patients with unstable angina presenting for PCI, we sought to evaluate our experience by retrospectively comparing the effect on myocardial perfusion between abciximab and eptifibatide following PCI in stable angina or acute coronary syndrome. Microcirculatory perfusion was reviewed in 101 consecutive patients (23 stable angina, 61 unstable angina, 17 non-q MI) undergoing PTCA/stenting. This comparison was between the last group of 51 patients who routinely received standard bolus and infusion of abciximab and the first group of 50 patients who began receiving standard bolus and infusion of eptifibatide. Baseline characteristics between the two groups were balanced, except for more patients with previous CABG in the eptifibatide group. Angiograms were evaluated by 2 blinded independent reviewers for MBG as follows: 0, no blush; 1, minimal blush; 2, moderate blush; and 3, normal blush. TIMI 3 flow was seen in 98 patients. MBG scores were not significantly different in the abciximab group (67% MBG 3; 31% MBG 2; 2.0% MBG 0 1) than in the eptifibatide group (58% MBG 3; 36% MBG 2; 6.0% MBG 0 1); p = 0.34. Patients with prior PTCA/stenting had lower MBG scores (0 2) compared to patients without prior PTCA (58% vs 31%; p = 0.03). There were significantly lower MBG scores in all patients with prior PTCA or CABG compared to patients without (55% vs 30%; p = 0.03). MBG scores significantly and inversely correlated with peak troponin I levels (r = -0.18, one-tailed p = 0.04). The similarity in myocardial perfusion between abciximab and eptifibatide suggests that both compounds are equally effective in reducing platelet aggregation and microembolization during mechanical reperfusion. Lower MBG scores in patients with prior PTCA or revascularization may be explained by irreversible microvascular dysfunction resulting from distal microembolization during the previous procedure. Lower MBG scores in patients with higher troponin I levels may reflect more frequent microemboli and microinfarcts during an ischemic event. Larger prospective studies need to be performed to validate these findings.

Abciximab↗

PubMed2003

[Changes of regional hemodynamics and microcirculation in tissues of lower extremities in patients with obliterating atherosclerosis in stages I and II].

Basing on analysis of results of ultrasonic investigation and laser Doppler flowmetry, performed in 125 patients with obliterating atherosclerosis of lower extremities arteries in I-II stages, the criterions of the chronic arterial insufficiency severity diagnosis were determined. There was established, that in high functional reserve of microcirculation present it is expedient to recommend to the patients the conservative treatment, as well as physiotherapeutic and sanatorium health resort procedures.

Arteriosclerosis↗

PubMed1992

[Experimental study on monitor of microcirculation of random skin flaps and early division of their pedicles].

In a series of 30 random skin flaps formed in pigs, the skin capillary blood flow was measured with laser doppler flowmetry (LDF) pre-, and postoperatively and within 48 hours after pedicle division. The results showed that the change in the microcirculation can be divided into three phases: (1) rapid rising, (2) plateau, and (3) slow rising. The plateau stage may be considered as the critical period. Division of the flap before this "critical" period causes flap necrosis, while division after the period resulted in flap survival (100 percent). Comparison of preoperative and postoperative LDF values can be regarded as a reliable objective criterion for division of the pedicle.

Animals↗

PubMed1992

[A study on virus localization and microcirculation in the liver in patients with epidemic hemorrhagic fever].

The findings in our clinical study was consistent with those reported by others that a temporary elevation of serum alanine aminotransferase activity is associated with epidemic hemorrhagic fever (EHF). However, the pathogenesis of the concomitant changes in liver function tests is still not clear. To clarify whether EHF virus is cytopathic or not for the liver, percutaneous liver biopsy was done in 19 patients with EHF within 3-12 days after the onset of symptoms. These liver biopsy specimens were examined with immunofluorescence assay and cell cultural technique, showing the presence of active viral replication in liver cells. Electron microscopy observation of the infected liver cells showed that ultrastructural distortions was accompanied by the existence of inclusion bodies of EHF virus in vacuoles of rough endoplasmic reticulum, endotheliocyte and microvilli. These findings strongly suggest that EHF virus may play a causative role in liver injury in patients suffering from EHF and hepatic microcirculation disturbance may be involved in the pathogenesis of EHF-related liver dysfunction as well.

Adolescent↗

PubMed1992

[Effect of hemosorption on microcirculation, humoral autoimmunity and lipid peroxidation in patients with stable angina pectoris].

Microhemo- and lymphocirculation, capillary permeability, humoral autoimmunity and lipid peroxidation were determined in 46 patients with Functional Classes III-IV stable angina concurrent with multiple atherosclerotic coronary lesions 24 hours following the second hemosorption session. The clinical efficiency of hemosorption was observed in 47.8% of patients with stenotic coronary atherosclerosis refractory to antianginal therapy. In this group of patients, hemosorption led to accelerated microcirculation, increased microcirculatory reserve potentials and decreased microvascular resistance at rest and in reactive postischemic hyperemia. In patients with abnormal humoral autoimmunity and lipid peroxidation, hemosorption resulted in their hormalization.

Angina Pectoris↗