Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “circulation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
PubMed2005

Differential response of the systemic and pulmonary circulation related to disease severity of cirrhosis.

BACKGROUND: In cirrhotic patients, the degree of hepatic insufficiency has been related to a physiological landmark: arterial vasodilatation. We sought to assess how the severity of disease, which was stratified according to the Child-Pugh criteria, influences the pulmonary and systemic circulation among patients undergoing liver transplantation. METHODS: We studied 86 cirrhotic patients in three groups: grade A (n = 10), grade B (n = 54), and grade C (n = 22). The outurnes were classified based upon a complete hemodynamic profile obtained using a pulmonary artery catheter (RVEF, Baxter-Edwards, Calif, USA) after induction of anesthesia. The variables were mean arterial and pulmonary artery pressures and cardiac index (CI). Using standard formulae, afterload was calculated as elastance of systemic (Es) and pulmonary (Ep) arterial beds, expressed by the ratio of end-systolic pressure to stroke volume. The relation between pulmonary and systemic circulation was also evaluated by the ratio (Ep/Es). RESULTS: Es was significantly lower in each class than in previous one. Also, Ep was smaller in class B than in class C patients. In addition, CI was significantly higher with disease severity. CONCLUSION: We observed that the hyperdynamic circulation in cirrhosis is directly related to severity of disease. Nevertheless Ep/Es was progressively higher among each group; these data suggest that the hyperdynamic circulation is mainly due to circulatory alterations in the splanchnic area. We conclude that pulmonary vasodilatation is directly related to the severity of cirrhosis, although its evolution is independent of other vascular areas.

Blood Circulation↗
PubMed1978

Circulating lymphocytes and the spread of myeloma. Review of the evidence.

Patients with myeloma harbour circulating lymphocytes which bear the idiotypic determinants (SIg-id+ cells) of their own myeloma protein. Circulating white cells with abnormal karyotypes have been found in other patients with this disease. SIg-id+ lymphocytes have also been identified in the peripheral blood of myeloma-tumour-bearing mice. Murine myelomas have been propagated in vivo from circulating mononuclear cells that possessed myeloma-tumour-associated antigens. This and other evidence reviewed here points strongly to the involvement of circulating lymphocyte-like stem cells in the spread of human myeloma.

Animals↗
PubMed1998

Coronary collateral circulation behaviour and myocardial viability in chronic total occlusion treated with coronary angioplasty.

AIMS: We explored the role of microcirculation integrity following the chronic occlusion of an infarct-related artery to assess the behaviour of collateral circulation during and after reperfusion by coronary angioplasty METHODS AND RESULTS: Eighteen patients with a proximally occluded left anterior descending artery and firm evidence of intercoronary collateral circulation were studied with selective coronary angiography and selective intracoronary myocardial contrast echocardiography, before coronary angioplasty, and at 5 and 15 min and 12 h later. Myocardial enhancement during myocardial contrast echocardiography was evaluated with a semiquantitative score (0-3), which was correlated to basal and 6 months' regional left ventricular wall motion results. 16/18 procedures were successfully performed; four patients with an inadequate acoustic window were excluded. Restenosis was evident at the 6 months' follow-up in two patients. Basal myocardial contrast echocardiography indicated that 81/192 segments from the left anterior descending coronary artery and 90/192 from the right coronary artery were perfused; no perfusion was observed in 21 segments either before or after coronary angioplasty. After coronary angioplasty, the angiographic intercoronary collateral circulation immediately disappeared, and myocardial contrast echocardiography revealed that there was a progressive reduction of segments perfused by the right coronary artery and an increase in segments perfused by the left anterior descending coronary artery. Regional left ventricular wall motion analysis demonstrated that there was abnormal motion in 51/192 segments. There was no improvement in segments with score 0 and abnormal motion after 6 months (100% sensitivity), but 16/17 segments with score 3 did show an improvement (98% specificity). The predictive value of intermediate scores (1-2) in detecting long-term improvement, was only 43%. CONCLUSION: These data show that the adaptive mechanism observed in the behaviour of epicardial and microvascular circulation after reperfusion of a chronic occluded infarct-related artery can vary. In addition, this study clearly shows that microvascular integrity detected by myocardial contrast echocardiography can provide myocardial viability.

Aged↗
PubMedDate not supplied

A single skeletal muscle powered ventricle that assists both systemic and pulmonary circulations.

Extraaortic counterpulsation using skeletal muscle powered ventricles (SMPVs) has been studied mainly for the purpose of assisting the systemic circulation. The purpose of this study was to investigate the possibility of assisting both the systemic and pulmonary circulations using a single SMPV. An SMPV that counterpulses the systemic circulation is placed beside the right atrium (RA) or the right ventricle (RV), the former after procedures such as a Fontan operation, and the latter in cases of biventricular failure. Because the SMPV dilates passively during cardiac systole, it is designed to press the RA or the RV directly from outside. This study is a preliminary report, and only the ability of a specially constructed SMPV to dilate was assessed. Using seven dogs with heart failure, the SMPV dilated with an internal pressure of 88 mmHg and 1.0 cm, while the volume inside increased by 10.8 ml. From these results, it is suggested that the SMPV has enough dilating power to press the RA or to assist the RV while counterpulsing the systemic circulation.

Animals↗
PubMed1973

The continuous bioassay of the release and disappearance of histamine in the circulation.

1. The blood-bathed organ technique was used for the continuous assay of histamine in circulating blood.2. Longitudinal strips of cat or kitten terminal ileum detect concentrations of histamine of 2-5 ng/ml; these are below the threshold at which hypotension is induced in dogs.3. The cat or kitten terminal ileum also contract to bradykinin. However, the simultaneous use of a cat jejunum strip, which is selectively sensitive to bradykinin, will distinguish between histamine and bradykinin.4. The utility of the method for detecting and quantitating circulating histamine was exemplified by measuring: (a) its half-life in the circulation, (b) its disappearance during a passage through the vascular beds of lungs, liver and lower limbs, and (c) its release into the circulation by compound 48/80.

Animals↗
PubMed1970

Limitations of circulation time in the diagnosis of intracranial disease.

The mode circulation time was measured using intravenously injected technetium 99(m) and a collimation system devised to discriminate between the right and left sides of the head. The results in 21 normal men were used as a basis of assessing the findings in 205 patients, made up of five diagnostic groups (ischaemia, haematoma, subarachnoid haemorrhage, intracranial tumour, and head injury). The average mode circulation time in the affected hemisphere for the three groups with vascular disease was increased, but even in these groups half the patients had a mode circulation time within 1 SD of normal mean; similar results were found for asymmetry between the hemispheres. In serial measurements in 45 patients no correlation was found between change in mode circulation time and the clinical state. That so many results are within the normal range limits the value of this method.

Blood Circulation Time↗
PubMed1993

Capsaicin treatment blocks development of hyperkinetic circulation in portal hypertensive and cirrhotic rats.

To investigate a possible role of primary afferent innervation in the pathogenesis of hyperkinetic circulation in cirrhosis or portal hypertension, we used capsaicin to denervate the primary afferent nerves. Rat pups were injected with capsaicin (50 mg/kg) or a vehicle and were allowed to grow. When they reached young adulthood, operations to induce portal hypertension by portal vein stenosis or cirrhosis by bile duct ligation were performed. A control group had sham operation. Cardiac output and regional blood flows were measured in unrestrained conscious rats by radioactive microspheres. Capsaicin-treated portal hypertensive and cirrhotic rats had cardiac output and systemic vascular resistance similar to sham-operated rats, whereas the vehicle-treated portal hypertensive and cirrhotic rats showed the hyperkinetic circulation. No hemodynamic effect of capsaicin on sham-operated rats was detected. Capsaicin-treated rats did not demonstrate a splanchnic or renal hyperemia, but the percentage of cardiac output in these vascular beds was similar to controls. These results suggest that capsaicin treatment blocked the generalized vasodilatation in cirrhotic and portal hypertensive rats. Arterial pressure and heart rate were not modified in any group. These results show that denervation of capsaicin-sensitive primary afferent nerves in cirrhotic and portal hypertensive rats blocked the expected development of hyperkinetic circulation. We conclude that primary afferent innervation may be important in the genesis of hyperdynamic circulation in portal hypertension and cirrhosis.

Analysis of Variance↗
PubMed1987

Effects of parathyroid hormone on blood flow in different regional circulations.

Parathyroid hormone and, in particular, its 1-34 aminoterminal fragment, PTH-(1-34), are potent vasodilators of the coronary circulation. In addition the hormone exerts a powerful hypotensive effect in a variety of animals, suggesting that the polypeptide hormone is vasoactive in peripheral regional circulations as well. The purpose of this study was to determine the regional circulations that were responsive and the relative sensitivity of each to the vasoactive properties of the hormone fragment. An anesthetized instrumented open-chest and/or open-abdomen dog model was used. Blood flow was continuously monitored in left circumflex, left pulmonary, right renal, celiac, and superior mesenteric arteries. Doses of synthetic human PTH-(1-34) ranging from 0.00024 to 0.24 nmol/kg were administered by bolus intra-arterial injections. Although PTH-(1-34) produced a dose-related vasodilation in each of the above regional vascular beds, marked differences in sensitivity were observed. The peptide elicited large increases in coronary (178%) and celiac (162%) blood flow. Maximal renal and pulmonary responses were relatively small (increases of 30 and 23%, respectively). Compared with control values, blood flow in the superior mesenteric circulation increased only at the highest dose tested. Thus sensitivity to the vascular effects of the hormone fragment differs markedly between the regional vascular beds of the dog.

Animals↗
PubMed1999

Quantification of conversion and degradation of circulating angiotensin in rats.

The aim of the present study was to quantify with a uniform technique the rates of conversion of ANG I to ANG II in the lung and kidney and the degradation of both peptides to biologically inactive products in the pulmonary, renal, and systemic circulation. We infused the peptides intravenously, into the left ventricle, and into the left renal artery of rats and compared their effects on renal blood flow. The measured change in renal blood flow was used as a bioassay parameter to estimate the concentration of circulating ANG II. Mathematical analysis of our data allowed us to calculate conversion and degradation rates. Furthermore, the role of aminopeptidases A (EC 3.4.11.7) and N (EC 3.4.11.2) in the degradation of the peptides in the kidney was investigated by intrarenal infusion of the inhibitor amastatin. Our results show that the conversion rate of ANG I is 75% in the pulmonary and 21% in the renal circulation. Both peptides are degraded by 5% in the pulmonary, by 67% in the systemic, and by 93% in the renal circulation. Amastatin prevented 60% of the renal degradation of the peptides to inactive products, and this effect could be attributed to inhibition of aminopeptidase N. The results indicate that the converting capacity of the kidney is of minor importance for endocrine generation of ANG II but could be useful for the paracrine production.

Aminopeptidases↗
PubMed1992

Differential uptake of endothelin-1 by the coronary and pulmonary circulations.

Substantial removal of the vasoconstrictor peptide endothelin-1 (ET-1) by the pulmonary circulation has been reported to occur in perfused guinea pig and rat lungs. We examined the uptake of ET-1 by coronary and pulmonary circulations of the rabbit by measuring single-pass extraction of ET-1 in the isolated heart and lung. In separate experiments, each organ was perfused at 30 ml/min with Krebs-albumin (3%) solution. A bolus of 125I-ET-1 and [14C]dextran in 0.3 ml Krebs-albumin solution was injected, and extraction of endothelin (EET), relative to that of an intravascular reference indicator, [14C]dextran, was determined by multiple indicator-dilution technique. EET was 5 +/- 2% (SE) in the heart and 49 +/- 4% in the lung. Increasing flow rate in the lung preparation to approximate the mean transit time in the heart preparation did not significantly alter EET. Despite insignificant uptake of ET-1, the coronary circulation extracted an angiotensin-converting enzyme inhibitor (351A) and metabolized a synthetic angiotensin-converting enzyme substrate (benzoyl-phenyl-alanyl-proline), both properties of the normal pulmonary circulation. We therefore conclude that there is no significant ET-1 uptake in the coronary vascular bed.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2005

Time course of changes in optic nerve head circulation after acute reduction in intraocular pressure.

PURPOSE: To study the time course of changes in circulation in the optic nerve head (ONH) after acute reduction in intraocular pressure (IOP) and to evaluate the effects of a calcium antagonist, a nitric oxide synthetase (NOS) inhibitor, indomethacin, and sympathetic nerve amputation on the changes in ONH circulation after reduction of IOP. METHODS: In anesthetized albino rabbits, acute reduction of IOP (acute increase in ocular perfusion pressure [OPP]) was manometrically achieved and normalized blur (NB), a quantitative index of tissue blood velocity obtained with the laser speckle method, was serially monitored for 30 seconds and 60 minutes. The effects of systemic administration of 1 microg/kg per hour nilvadipine (a calcium antagonist), 300 microg/kg Nomega-nitro-l-arginine (l-NAME, a nonselective NOS inhibitor), and 5 mg/kg indomethacin or sympathetic nerve amputation on the changes in NB after reduction of IOP were studied. RESULTS: During changes in IOP from 10 to 40 mm Hg and then back to 10 mm Hg, NB exhibited no significant change. During changes in IOP from 10 to 60 mm Hg and then back to 10 mm Hg, NB initially decreased with an increase in IOP to 60 mm Hg and then increased to baseline level when IOP was returned to 10 mm Hg. In the nilvadipine-treated rabbits, during changes in IOP from 10 to 40 mm Hg and back to 10 mm Hg and during the changes from 10 to 60 mm Hg and back to 10 mm Hg, NB decreased with increase in IOP to 40 or 60 mm Hg and then increased to slightly above the baseline when IOP returned to 10 mm Hg. l-NAME, indomethacin, and sympathetic nerve amputation each had little effect on the time course of change in NB. CONCLUSIONS: ONH circulation was stably maintained after reduction of IOP from 40 to 10 mm Hg but not after that from 60 to 10 mm Hg. The changes in NB after reduction of IOP occurred quickly and were partially impaired with a calcium antagonist, but not with the NOS inhibitor, indomethacin, or sympathetic nerve amputation. These findings suggest the importance of vascular smooth muscle in maintaining stable ONH circulation against reduction of IOP in a fashion nearly independent of NO, endogenous prostaglandins, and the sympathetic nervous system.

Acute Disease↗
PubMed2005

The effects of pulsatile versus non-pulsatile extracorporeal circulation on the pattern of coronary artery blood flow during cardiac arrest.

BACKGROUND: In sudden cardiac arrest, the effective maintenance of coronary artery blood flow is of paramount importance for myocardial preservation as well as cardiac recovery and patient survival. The purpose of this study was to directly compare the effects of pulsatile versus non-pulsatile circulation to coronary artery flow and myocardial preservation in a cardiac arrest condition. METHODS: A cardiopulmonary bypass circuit was constructed in a ventricular fibrillation model using fourteen Yorkshire swine weighing 25-35 kg each. The animals were randomly assigned to group I (n=7, non-pulsatile centrifugal pump) or group II (n=7, pulsatile T-PLS pump). Extracorporeal circulation was maintained for two hours at a pump flow of 2 L/min. The left anterior descending coronary artery flow was measured with an ultrasonic coronary artery flow measurement system at baseline (before bypass) and at every 20 minutes after bypass. Serologic parameters were collected simultaneously at baseline, 1 hour, and 2 hours after bypass in the systemic arterial and coronary sinus venous blood. The Mann-Whitney U test of STATISTICA 6.0 was used to determine intergroup significances using a p value of <0.05. RESULTS: The resistance index of the coronary artery was lower in group II and the difference was significant at 40 min, 80 min, 100 min and 120 min (p<0.05). The mean velocity of the coronary artery was higher in group II throughout the study, and the difference was significant from 20 min after starting the pump (p<0.05). The coronary artery blood flow was higher in group II throughout the study, and the difference was significant from 40 min to 120 min (p<0.05) except at 80 min. Serologic parameters showed no differences between the groups at 1 hour and 2 hours after bypass in the systemic and coronary sinus blood (p=NS). CONCLUSION: In the cardiac arrest condition, pulsatile extracorporeal circulation provides more blood flow, higher flow velocity and less resistance to coronary artery than non-pulsatile circulation.

Animals↗
PubMed1997

Evaluation of coronary collateral circulation in early ischemia in rat hearts. A morphological study.

Histological changes were examined in the left ventricular free wall of the heart in 40 rats after ligation of the distal anterior descending coronary artery for 15, 30 minutes and 1, 2, 3, 4, 5, 6 hours. Auto-injection of tracers for light microscopy was used to examine the development of collateral circulation. Morphological changes of the ischemic myocardium were observed by PAS staining and transmission electron microscopy. Fifteen minutes after coronary occlusion, the dye was observed in the vein of the ischemic zone; however, 30 minutes after coronary occlusion, the dye appeared in the capillaries of the outer-third layer. These findings suggested that the collateral circulation becomes functional between 15 and 30 minutes after coronary occlusion. Collateral circulation increased gradually in the capillaries of the ischemic zone. Thirty minutes after coronary occlusion the dye was seen only in the outer-third layer of the ventricular ischemic zone. One hour after occlusion, the dye appeared in the superficial space and the middle-third layer. Three hours after occlusion, the dye was seen in all layers of the ischemic zone. The dye appeared in the ischemic zone, where myocardium damage was not homogeneous. The positive reaction obtained by PAS staining corresponded with the capillaries, veins and superficial spaces in which the dye was evident. These results suggest that collateral circulation, verural back flow and superficial space flow are able to prevent myocardial infarction in early ischemia.

Animals↗
PubMed2006

Angiotensin II type 1 receptor blockers do not promote coronary collateral circulation in patients with coronary artery disease.

We previously reported that angiotensin-converting enzyme inhibitors (ACE-Is) promote collateral circulation in patients with coronary artery disease (CAD). There have been many reports on the beneficial effects of angiotensin II type 1 receptor blockers (ARBs) on the cardiac microvasculature. Therefore, the following studies were performed to evaluate the association between treatment with an ARB and the enhancement of coronary collateral circulation as assessed by the Rentrop Score (RS) (Study 1) and to compare these results to those obtained with an ACE-I (Study 2). The subjects were 456 patients with angina who underwent coronary angiography. Study 1: Those who had one (1-V), two (2-V) or three significantly stenosed vessels (3-V) and who received only an ARB without any other anti-hypertensive medication were defined as the ARB group (n=81), and age-, sex- and body mass index-matched subjects (n=146) were selected as a comparative group. There were no significant differences in the percentage of patients with RS>or=1 between the two groups. Study 2: Those who received an ACE-I as the only anti-hypertensive treatment were defined as the ACE-I group (n=67), which was matched to the ARB group in Study 1. The percentage of patients with RS>or=1 in the ACE-I group was significantly higher than that in the ARB group as assessed by a Cochran-Mantel-Haenszel analysis. In addition, patients with 3-V disease who were treated with an ACE-I, but not an ARB, were most likely (odds ratio [confidence Interval]): 27.7 [4.8-161.0]) to show enhanced collateral circulation, as assessed by a multiple logistic regression analysis. These results suggest that treatment with an ACE-I, but not treatment with an ARB, was associated with the enhancement of collateral circulation in patients with CAD.

Aged↗
PubMed1998

Functional assessment of collaterals in the human coronary circulation.

The coronary collateral circulation is an alternative source of blood supply to a myocardial area jeopardized by the failure of the stenotic or occluded vessel to provide enough blood flow to this region. Until recently, only qualitative or semiqualitative methods have been available for the assessment of the coronary collateral circulation in humans, such as the patient's history of walk-through angina pectoris, the registration of intracoronary ECG signs for myocardial ischaemia or angina pectoris during coronary occlusion, or coronary angiographic classification (score 0-3) of collaterals. Studies of coronary wedge pressure measurements distal of a balloon-occluded coronary artery and the recent advent of ultrathin pressure and Doppler angioplasty guidewires have made it possible to obtain pressure or flow velocity data in remote vascular areas and, thus, to calculate functional variables for coronary collateral flow. Those coronary occlusive pressure- and flow velocity-derived parameters express collateral flow as a fraction of antegrade coronary flow during vessel patency of the collateral-receiving vessel. They are both interchangeable, and they have been validated in comparison to 'traditional' methods and against each other. The possibility of accurately measuring coronary collateral flow indices in humans undergoing coronary balloon angioplasty opens areas of investigation of the pathogenesis, pathophysiology and therapeutic promotion of the collateral circulation previously reserved for exclusively experimental studies. The purpose of this article is to review several clinically available methods for the functional characterization of the coronary collateral circulation.

Angina Pectoris↗
PubMed1999

[Immediate collateral coronary circulation after a methylergometrin test].

The development of a collateral coronary circulation has been well studied by angiography in two main clinical situations: myocardial infarction (by durable coronary occlusion) and angina (due to significant coronary artery stenosis), but only rarely in spastic angina. The authors report the case of severe spasm at the site of non-significant stenosis after a methylergometrine test, with immediate contro-lateral collateral circulation in a patient with a short history of spastic angina without myocardial infarction. This observation demonstrates that collateral circulation may develop very rapidly in spastic angina (without basal ischaemia in the absence of significant coronary stenosis), because this patient only had seven ten-minute episodes of clinical ischaemia. As collateral circulation may mask clinical and electrical signs in spastic angina, this case suggests that angiographic control should be systematic during the methylergometrine test.

Collateral Circulation↗
PubMed1998

[Effect of 7 d head down bed rest on cardiopulmonary circulation in human].

Changes of cardiopulmonary circulation in 6 healthy young men during 7 d head down bed rest (-6 degrees HDT) were observed with the XXH-2000 lesser circulation and cardiac function instrument. Decrease of Q-j and Q-j/j-z, increase of hz, hc, and hc/hz were found during the initial 24 h. After 24 h, j-z decreased and Q-j/j-z increased. The results showed that increased pulmonary arterial pressure, increased preload of left and right heart, increased right myocardial contractility and congestion of the lungs appeared during 24 h bed rest, after which right myocardial contractility decreased. It suggests that the lesser circulation and cardiac function testing is a sensitive method for evaluating the cardiopulmonary circulation function during HDT.

Adult↗
PubMed2002

[Are there effects due to the existence of coronary collateral circulation on left ventricular function in patients with coronary artery disease?].

OBJECTIVE: The role of coronary collateral circulation (CCC) on the improvement of left ventricular function in coronary artery disease is controversial. The aim of this study is to investigate the effect of CCC on left ventricular function in patients with ischaemic heart disease. METHODS: Accordingly, 76 patients (39 female, 37 male, mean age--61 +/- 17 years) who had single vessel disease with > 85% narrowing in left anterior descending coronary artery were enrolled in this study. Coronary collateral circulation was determined according to the Rentrop classification (Class 0 = no collateral circulation; class 1 = small branches of occluded vessel fill with CCC; class 2 = epicardial segment of the occluded vessel partially fills with CCC; class 3 = epicardial segment of the occluded vessel totally fills with CCC). Left ventricular function was assessed with echocardiography and left ventricular regional wall motion score (0 = normokinetic; 1 = hypokinetic; 2 = akinetic; 3 = dyskinetic; 4 = aneurysmatic). Rentrop classification of the patients were compared with left ventricular regional wall motion scores and ejection fractions. RESULTS: Twenty one of 76 patients had no collateral circulation. The regional wall motion score of class 0 patients was similar with that of patients with CCC (class 1,2,3) (2.28 +/- 2.1 vs 3.39 +/- 2.1, p > 0.05). Particularly, the regional wall motion score was positively correlated with Rentrop classes (p < 0.05). Class 3 patients had the highest wall motion score (4.24 +/- 2.5, p < 0.05). Patients with and without CCC had similar left ventricular ejection fractions (49 +/- 11 vs 46 +/- 17, p > 0.05). CONCLUSION: This study showed that development of CCC has no preventive effect on left ventricular functions in patients with coronary artery disease. Interestingly as the stage of CCC increases left ventricular function worsens. It may be the result of the fact that patients with well developed CCC have more severe coronary artery disease.

Collateral Circulation↗