Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PERFUSION”

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 235 records · Page 13Linked to original sources
PubMed1981

[Effect of pressure and local adrenaline application on carotid sinus on the perfusion pressure in the perfused hindlimb].

On anaesthetized dogs the response of the perfusion pressure of a volume-constant perfused hindlimb and of the systemic arterial blood pressure during mechanical stimulation of the sinual baroreceptors, resulting in a rectangular increase in the intrasinual pressure and during local application of adrenaline at both carotid sinus bifurcations was determined, leaving the vagoaortic trunks intact. The mechanical stimulation of the sinual baroreceptors as well as the local application of adrenaline induced a pronounced decrease in the perfusion associated with a simultaneous fall in the systolic and diastolic blood pressure. The maximal decrease in systolic blood pressure at both types of stimulation was similar, however, the maximal fall in the perfusion pressure after application of adrenaline was less than that after rectangular mechanical stimulation of the sinual baroreceptors. A decrease in the heart rate after application of adrenaline was not observed. The mechanical stimulation of sinual baroreceptors before or after local application of adrenaline resulted in a similar decrease in the perfusion pressure of the perfused hindlimb.

Animals↗
PubMed1997

Laser Doppler perfusion imaging: new technique for determination of perfusion and reperfusion of splanchnic organs and tumor tissue.

BACKGROUND AND OBJECTIVE: Several investigations indicated that laser Doppler flowmetry on the liver surface reflects relative changes of the total liver blood flow. In this study, Laser Doppler Perfusion Imaging (LDI), monitoring the surface only, was used for measurements of tissue perfusion of normal and/or impaired liver, pancreas, spleen, stomach and intestines, and the blood flow of hepatic tumors in rats. STUDY DESIGN/MATERIALS AND METHODS: Eighty Wistar/Furth rats were divided into five groups. Group I served as controls. Groups II and III underwent ischemic injury of the liver and intestine with or without the administration of WEB2170, a platelet-activating factor receptor antagonist. Laser-induced photodynamic therapy (PDT) utilizing delta-amino levulinic acid sensitization was performed in Groups IV and V. RESULTS: Normal pancreas and intestine had a high LDI perfusion value and the liver and stomach exhibited a medium perfusion value whereas the perfusion value from the spleen was low. WEB2170 improved the reperfusion of the postischemic liver and intestine. An immediate decrease in surface blood flow of hepatic tissue treated by laser-induced PDT and a decreased blood flow in large tumors were observed. CONCLUSION: LDI is a useful technique for the measurement of tissue perfusion of various splanchnic organs or tumor tissues.

Aminolevulinic Acid↗
PubMed1990

Perfusion-time dependent enhancements of guanabenz- and KCl-induced vasoconstrictions in isolated and perfused dog pulmonary veins.

The responses of the isolated canine pulmonary vein to guanabenz and to potassium chloride (KCl) were examined by means of the cannula-inserting method. The vessel was perfused by Krebs-Ringer bicarbonate solution at a constant flow rate at 37 degrees C. In the early stage (within 2-3 hours of the perfusion period), guanabenz induced a dose-dependent vasoconstriction, whereas high doses of KCl caused, at most, a slight vasoconstriction. At the late stage (within 8-11 hours of the perfusion period), the dose-response curve for guanabenz was shifted to the left and the maximum response became approximately 3-fold larger than that in the early stage. Vasoconstriction in response to KCl was observed in 8 out of 11 preparations (73%) in the late stage. In both early and late stages, guanabenz-induced responses were similarly antagonized by DG-5128 (a selective alpha 2-adrenoceptor antagonist) but not by bunazosin (a selective alpha 1-adrenoceptor antagonist). Diltiazem caused an inhibition of guanabenz-induced constrictions, particularly in the late stage. KCl-induced vasoconstriction was not affected by bunazosin or DG-5128, but was markedly suppressed by diltiazem. In preparations in which the endothelium was removed by intraluminal treatment with saponin, the changes in guanabenz- and KCl-induced responses, which were dependent on the perfusion time, were not modified in either stage. Our results suggest that alpha 2-adrenoceptor-mediated vasoconstriction is enhanced in a perfusion-time-dependent manner in the isolated and perfused canine pulmonary vein. These enhanced responses mediated by latent alpha 2-adrenoceptors are dependent on the influx of extracellular calcium ions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed2004

Prevalence of symptomatic and silent stress-induced perfusion defects in diabetic patients with suspected coronary artery disease referred for myocardial perfusion scintigraphy.

PURPOSE: Silent myocardial ischaemia--as evaluated by stress-induced perfusion defects on myocardial perfusion scintigraphy (MPS) in patients without a history of chest pain--is frequent in diabetes and is associated with increased rates of cardiovascular events. Its prevalence has been determined in asymptomatic diabetic patients, but remains largely unknown in diabetic patients with suspected coronary artery disease (CAD) in the clinical setting. In this study we therefore sought (a) to determine the prevalence of symptomatic and silent perfusion defects in diabetic patients with suspected CAD and (b) to characterise the eventual predictors of abnormal perfusion. METHODS: The patient population comprised 133 consecutive diabetic patients with suspected CAD who had been referred for MPS. Studies were performed with exercise (41%) or pharmacological stress testing (1-day protocol, (99m)Tc-sestamibi, 201Tl or both). We used semi-quantitative analysis (20-segment polar maps) to derive the summed stress score (SSS) and the summed difference score (SDS). RESULTS: Abnormal MPS (SSS> or =4) was observed in 49 (37%) patients (SSS=4.9+/-8.4, SDS=2.4+/-4.7), reversible perfusion defects (SDS> or =2) in 40 (30%) patients [SSS=13.3+/-10.9; SDS=8.0+/-5.6; 20% moderate to severe (SDS>4), 7% multivessel] and fixed defects in 21 (16%) patients. Results were comparable between patients with and patients without a history of chest pain. Of 75 patients without a history of chest pain, 23 (31%, 95% CI=21-42%) presented reversible defects (SSS=13.9+/-11.3; SDS=7.4+/-1.2), indicative of silent ischaemia. Reversible defects were associated with inducible ST segment depression during MPS stress [odds ratio (OR)=3.2, p<0.01). Fixed defects were associated with erectile dysfunction in males (OR=3.7, p=0.02) and lower aspirin use (OR=0.25, p=0.02). CONCLUSION: Silent stress-induced perfusion defects occurred in 31% of the patients, a rate similar to that in patients with a history of chest pain. MPS could identify these patients with a potentially increased risk of cardiovascular events.

Adult↗
PubMed2002

Changed skin blood perfusion in the fingertip following acupuncture needle introduction as evaluated by laser Doppler perfusion imaging.

Rapidly repeated imaging of the left middle fingertip skin blood perfusion was performed in 51 healthy volunteers (mean age +/- SD: 25.3 +/- 7.6 years) prior to, immediately after and in the early reperfusion phase following introduction of an acupuncture needle at the Neiguan point (Pe. 6) and at a placebo point respectively, using a Laser Doppler Perfusion Imager (LDPI). The average skin perfusion of the fingertip was calculated for each image and used as an indicator of the microvascular response to the acupuncture needle introduction. The results of this randomised, placebo-controlled, cross-over study showed significant differences (p < or = 0.001) in the immediate skin blood perfusion response when needling is performed in an acupuncture point (Neiguan) and a placebo point, with a more pronounced reduction in skin blood perfusion when needling the acupuncture point. In the early reperfusion phase, however, a substantial increase in skin perfusion was observed that amounted to about 18% of the level prior to needle introduction, irrespective of the site of needle application. In a single individual it was demonstrated that the vasodilatation following needling in the acupuncture point persisted for a more extended time period. These results suggest that the LDPI technology may be useful in visualising and quantifying the peripheral vascular effects of acupuncture on the microcirculation.

Acupuncture↗
PubMedDate not supplied

Value of absence of a transient myocardial perfusion defect during stress myocardial perfusion study in patients undergoing major vascular surgery.

Pre-operative cardiac assessment is important in the evaluation of patients undergoing major vascular surgery. Our study aims to evaluate the value of absence of a transient myocardial perfusion defect during radionuclide myocardial perfusion study for prediction of cardiac events (myocardial infarction, sudden cardiac death, unstable angina, coronary artery revascularization and congestive heart failure) in patients undergoing major vascular surgery. We studied 63 consecutive patients (ages 35-83 [avg. 64], male 39, female 24) with radiographically proven, abdominal aortic aneurysm or severe aortofemoral occlusive disease who underwent major vascular surgery (abdominal aortic aneurysm repair [38] or aortofemoral bypass [25]). The subjects all had multiple coronary artery risk factors (hypertension 48, diabetes 10, hyperlipidemia 23, tobacco use 39, family history of coronary artery disease 10), but a negative pre-operative stress myocardial perfusion study for myocardial ischemia. Of these 63 patients, 17 patients were able to exercise and achieve their adequate 85% maximal predicted heart rate. Thirty-eight patients received adenosine infusion of 140 microg/kg/min for 6 min. Six patients received dipyridamole infusion of 0.56 mg/kg over 4 min. Two patients received dobutamine infusion at 5, 10, 20, 30, and 40 mg/kg/min. Of the 63 patients, 60 received 3-4 mCi of thallium-201 ((201)Tl) and 3 patients received 8-9 mCi of technetium-99m (99mTc) at rest and 25-30 mCi 99mTc during stress. The subjects all underwent major vascular surgery and were followed up to one year for any cardiac events. Of the 63, who underwent pre-operative cardiac assessment with myocardial perfusion testing, 25 had a fixed myocardial perfusion defect (scar) and none had evidence of transient myocardial perfusion defect (ischemia). One subject had coronary artery bypass grafting 11 months after aortofemoral bypass surgery. One died from a stroke one month after aortofemoral bypass surgery. Of the remaining 61 patients, none had any cardiac events up to one year after major vascular surgery.

Adenosine↗
PubMed1999

Retrograde cerebral perfusion versus selective cerebral perfusion as evaluated by cerebral oxygen saturation during aortic arch reconstruction.

BACKGROUND: Time limits for neuroprotection by retrograde cerebral perfusion (RCP) and selective cerebral perfusion (SCP) in aortic arch aneurysm repair or dissection are undergoing definition. METHODS: Using near-infrared optical spectroscopy, changes in regional cerebrovascular oxygen saturation (rSO2) were compared between the two perfusion methods. RESULTS: Immediately before cardiopulmonary bypass, baseline rSO2 was 63.9%+/-6.9% for the RCP and 66.1%+/-5.3% for the SCP group (no significant difference). As patients were core-cooled to 20 degrees C, rSO2 increased to 73.1%+/-8.8% and 74.1%+/-7.9% in the RCP and SCP groups, respectively. With circulatory arrest, rSO2 suddenly decreased. After starting cerebral perfusion, rSO2 returned to prearrest values in the SCP group but continued decreasing steadily in the RCP group, to levels below baseline after about 25 minutes. At the end of perfusion, rSO2 was 57.4%+/-12.2% for the RCP group and 71.7%+/-6.9% for the SCP group, and the ratio of rSO2 to baseline value was 0.89 for RCP and 1.08 for SCP despite a shorter brain perfusion time for RCP (38.8+/-18.0 versus 103.3+/-43.3 minutes). Three of 5 patients whose ratios of rSO2 to baseline at the end of brain protection were 0.7 or less had neurologic deficits. CONCLUSIONS: Although SCP showed no clinically important time limitation, rSO2 continued to decrease with time during RCP. An rSO2 ratio less than 0.7 could represent a critical lower limit.

Aged↗
PubMed2003

Reduced myocardial perfusion reserve and transmural perfusion gradient in heart transplant arteriopathy assessed by magnetic resonance imaging.

OBJECTIVES: The goal of this study was to detect transplant arteriopathy (Tx-CHD) by a reduced myocardial perfusion reserve (MPR) and resting endomyocardial/epimyocardial perfusion ratio (Endo/Epi ratio). BACKGROUND: Transplant arteriopathy often lacks clinical symptoms and is the reason for frequent surveillance angiography in heart transplant (Tx) recipients. Magnetic resonance perfusion imaging (MRPI) allows noninvasive assessment of transmural and selective endomyocardial and epimyocardial perfusion. METHODS: Fifteen healthy volunteers (controls) and three groups (A, B, C) of Tx recipients were included. In controls and patients, MPR (hyperemic/resting perfusion) and Endo/Epi ratio were determined with MRPI after injection of gadolinium-diethylenetriamine pentaacetic acid at rest and during hyperemia (intravenous adenosine). Group A (n = 10) had no left ventricular (LV) hypertrophy and/or prior rejection, while patients in group B (n = 10) had at least one of these characteristics. Patients in group A and B had a normal coronary angiogram and a coronary flow reserve (CFR) of > or =2.5 (CFR = hyperemic/resting blood flow). Group C (n = 7) had Tx-CHD diagnosed by angiography and a reduced CFR (<2.5). RESULTS: In group C, MPR (1.7 +/- 0.5) and Endo/Epi ratio (1.1 +/- 0.2) were significantly reduced compared with controls (4.2 +/- 0.7 and 1.6 +/- 0.3; both p < 0.0001), group A (3.6 +/- 0.7 and 1.6 +/- 0.2; both p < 0.0001) and B (2.7 +/- 0.9, p < 0.01 and 1.4 +/- 0.1, p < 0.04). Transplant arteriopathy can be excluded by an MPR of >2.3 with sensitivity and specificity of 100% and 85%. If LV hypertrophy and prior rejection are excluded, Tx-CHD can be excluded by an Endo/Epi ratio of >1.3 with 100% and 80%. CONCLUSIONS: Magnetic resonance perfusion imaging detects Tx-CHD by a decreased MPR. After exclusion of LV hypertrophy and prior rejection, resting Endo/Epi ratio alone might be sufficient to indicate Tx-CHD.

Adult↗
PubMed2000

Cerebral perfusion abnormalities in abstinent cocaine abusers: a perfusion MRI and SPECT study.

Nuclear medicine studies found decreased regional cerebral blood flow (rCBF) in the cortex and deep gray matter of cocaine users. Perfusion magnetic resonance imaging (MRI), a non-radioactive technique, has not been applied to evaluate persistent rCBF abnormalities. Twenty-five abstinent cocaine users and 15 healthy subjects without a history of drug use were examined with perfusion MRI, using dynamic bolus-tracking, and single photon emission computed tomography (SPECT), using 133Xe-calibrated 99mTc-HMPAO. After coregistration of SPECT with MRI, the relative rCBF (from perfusion MRI and SPECT) and absolute rCBF (from SPECT) were determined in 10 brain regions in each hemisphere. There was a statistically significant interaction between drug use and brain region on SPECT alone (relative and absolute rCBF), and on SPECT and perfusion MRI combined, but not on perfusion MRI alone. There also was a significant interaction among gender, drug use, and brain region. Compared to the control subjects, cocaine users showed increased rCBF in the frontal white matter (+8.6%, P=0.02) and in the globus pallidus (+6.3%, P=0.05), and decreased rCBF in the putamen (-3.9%, P=0.04) and the temporal cortex (-2.4%, P=0.02). SPECT and perfusion MRI detect a regional pattern of rCBF abnormalities in cocaine users that is consistent across the two methods. The hypoperfusion in the cortex and deep gray matter of the cocaine users is consistent with previous results. The increased rCBF in the white matter of cocaine users may be due to the presence of reactive glia.

Adolescent↗
PubMedDate not supplied

Usefulness of thallium-201 muscle perfusion scan to investigate perfusion reserve in the lower limbs of Type 2 diabetic patients.

This study evaluated the usefulness of thallium-201 muscle perfusion scan (Tl-201 muscle scan) to investigate perfusion reserve in the lower limbs of asymptomatic Type 2 diabetic patients without peripheral ischemia findings. Tl-201 muscle scan was carried out in 36 diabetic male patients with Type 2 diabetes mellitus of more than 10 years in duration who had no evidence of peripheral arterial disease in their history, physical examination, or Doppler ultrasonography. A control group consisted of 24 healthy age-matched nondiabetic men. Each subject flexed their right foot maximally both dorsally and plantar 60 times. In the middle of this exercise, 2mCi Tl-201 was injected intravenously. Three minutes after the injection, a posterior image of both calves was obtained using a gamma camera. Rectangular regions of interest (ROIs) were symmetrically drawn over both calves. The total count (Ct) in the resting calf was subtracted from the Ct in the exercising calf, and the percentage increase, termed the perfusion reserve, was determined. A significant difference was found between the perfusion reserves of the Type 2 diabetic patients and control groups (70.2+/-10.7% and 98.6+/-9.4%, respectively; P<.05). In conclusion, the perfusion reserve in the lower limb muscles in Type 2 diabetic patients may be measured by Tl-201 muscle perfusion scan.

Body Mass Index↗
PubMed1981

Degradation of insulin in perfused liver and skeletal muscle and insulin secretion in perfused pancreas of liver injury rat.

To study the mechanism of hyperinsulinism and glucose intolerance in liver disease, insulin removal rate by liver and muscle, glucose uptake by muscle and insulin secretion from pancreas were measured using the perfusion in rats with injured liver induced by carbon tetrachloride (liver injury rat). In the perfused liver, insulin removal rate of liver injury rat decreased to 62% of that of normal rat, but it did not alter in the perfused muscle. Insulin response to arginine by the perfused pancreas of liver injury rat was similar to that of normal rat. Before insulin infusion, glucose uptake by the perfused muscle was similar in liver injury rat and normal rat. In contrast, during insulin infusion, glucose uptake by the perfused muscle was 1.5 times higher in liver injury rat than in normal rat. These results suggested that the peripheral hyperinsulinism was solely due to decreased hepatic insulin degradation, but not hypersecretion of insulin from pancreas and furthermore, might suggest that the insulin resistance was related to appearance of biologically inactive endogenous insulin, because of exogenous insulin completely acting on peripheral target tissue.

Animals↗
PubMed2002

Assessment of perfusion of facial microvascular transplants and early detection of ischemia by perfusion-CT scan.

OBJECTIVE: Perfusion-computed tomography (CT) is a promising new technique to assess ischemic lesions caused by ischemic brain stroke. In this study, the use of perfusion-CT scans to predict ischemia in microvascular transplants of the face was examined. STUDY DESIGN: Thirty-eight patients with microvascular latissimus dorsi transplants after tumor surgery were assessed by perfusion-CT scan 34 to 72 hours after surgery. In these cases, clinical examination of the transplant and examination by means of O(2)-probes were either unsuccessful or impossible. An electron beam tomography of the region of interest was performed by using an intravenous nonionic iodine-containing contrast medium (Ultravist 300, Nycomed, Germany) that was applied with an injector at a flow rate of 5 mL/min. Twenty scans with a scanning time of 300 ms and an interscanning time of 3 seconds were carried out. Changes in the Houndsfield units within the transplant as well as the region of the contralateral erector spinae muscle were measured. RESULTS: Central malperfusion resulting in later complete transplant loss was detected in 2 cases. Peripheral malperfusion was found in 6 cases, resulting in localized resection and secondary wound closure. When no malperfusion was registered, the straightforward healing process took place. CONCLUSION: Perfusion-CT scans are of great aid in the assessment of microvascular transplant perfusion in the face, when adequate perfusion is not verifiable clinically or by O(2)-probe because of removal or malfunction.

Bone Transplantation↗
PubMed2005

Enhanced perfusion defect clarity and inhomogeneity in smokers' lungs with deep-inspiratory breath-hold perfusion SPECT images.

PURPOSE: Deep-inspiratory breath-hold (DIBrH) Tc-99m-macroaggregated albumin (MAA) SPECT images were developed to accurately evaluate perfusion impairment in smokers' lungs. METHODS: DIBrH SPECT was performed in 28 smokers with or without low attenuation areas (LAA) on CT images, using a triple-headed SPECT system and a laser light respiratory tracking device. DIBrH SPECT images were reconstructed from every 4 degrees projection of five adequate 360 degrees projection data sets with almost the same respiratory dimension at 20 sec DIBrH. Perfusion defect clarity was assessed by the lesion (defect)-to-contralateral normal lung count ratios (L/N ratios). Perfusion inhomogeneity was assessed by the coefficient of variation (CV) values of pixel counts and correlated with the diffusing capacity of the lungs for carbon monoxide/alveolar volume (DLCO/VA) ratios. The results were compared with those on conventional images. RESULTS: Five DIBrH projection data sets with minimal dimension differences of 2.9+/-0.6 mm were obtained in all subjects. DIBrH images enhanced perfusion defects compared with conventional images, with significantly higher L/N ratios (P<0.0001), and detected a total of 109 (26.9%) additional detects (513 vs. 404), with excellent inter-observer agreement (kappa value of 0.816). CV values in the smokers' lungs on DIBrH images were also significantly higher compared with those on conventional images (0.31+/-0.10 vs. 0.19+/-0.06, P<0.0001). CV values in smokers on DIBrH images showed a significantly closer correlation with DLCO/VA ratios compared with conventional images (R = 0.872, P<0.0001 vs. R=0.499, P<0.01). CONCLUSION: By reducing adverse effect of respiratory motion, DIBrH SPECT images enhance perfusion defect clarity and inhomogeneity, and provide more accurate assessment of impaired perfusion in smokers' lungs compared with conventional images.

Artifacts↗
PubMed2006

Real-time perfusion adenosine stress echocardiography versus myocardial perfusion adenosine scintigraphy for the detection of myocardial ischaemia in patients with stable coronary artery disease.

BACKGROUND: Real-time perfusion (RTP) contrast echocardiography using low mechanical index power modulation technique allows for simultaneous myocardial perfusion and wall motion analysis. RTP-adenosine stress echocardiography (ASE) could be an alternative to dobutamine-atropine stress echocardiography; more tolerable for the patients and possibly similarly accurate. We aimed to evaluate RTP-ASE for the detection of myocardial ischaemia, compared to 99mTc-sestamibi single-photon emission computed tomography (SPECT). METHODS: Patients with suspected coronary artery disease, admitted to SPECT evaluation, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using infusion of Sonovue (Bracco, Milano, Italy) before and during ASE. Two separate readers performed off-line analysis of myocardial perfusion and wall motion by RTP-ASE. A perfusion defect was the principal marker of ischaemia. Wall motion assessment was used to evaluate ischaemia in segments with perfusion artefacts. Each segment was attributed to one of the three main coronary vessel areas of interest: the left anterior descending (LAD); the left circumflex (LCx) and the right posterior descending (RPD). Normal SPECT at stress was judged normal at rest. RESULTS: In 33 patients, 99 coronary territories were analysed by SPECT and RTP-ASE. SPECT showed evidence of ischaemia in 9 of 33 patients. For the detection of ischaemia, the overall level of agreement between RTP-ASE and SPECT was 92% in all segments. The level of agreement was 88% in LAD, 97% in LCx and 91% in RPD segments. CONCLUSION: Real-time perfusion-adenosine stress echocardiography using power modulation could be an accurate and feasible tool for evaluation of ischaemia in patients with suspected coronary artery disease. The results from this study need confirmation by a study of a larger patient sample.

Adenosine↗
PubMed2005

Myocardial perfusion after angioplasty in patients suspected of having single-vessel coronary artery disease: improvement detected at rest-stress first-pass perfusion MR imaging--initial experience.

PURPOSE: To prospectively assess myocardial perfusion before and after successful intervention in patients suspected of having single-vessel coronary artery disease by using a steady-state free precession (SSFP) perfusion magnetic resonance (MR) imaging sequence. MATERIALS AND METHODS: Local ethics committee approval and informed consent were obtained. Rest-stress perfusion MR imaging studies were performed in 18 patients with coronary artery disease (12 men, six women; mean age, 58.6 years +/- 13.6 [standard deviation]; range, 30-79 years) at 1.5 T with a multisection saturation-recovery SSFP sequence and 0.025 mmol gadopentetate dimeglumine per kilogram of body weight. MR studies were performed before (n = 18), several days after (n = 18), and 8 months after (n = 10) coronary intervention. Nine patients underwent percutaneous transluminal coronary angioplasty (PTCA) alone, and nine patients underwent PTCA with stent placement. Myocardial perfusion reserve index (MPRI) was calculated by dividing results of myocardial perfusion at maximal vasodilation by results at rest. The standard for myocardial perfusion was technetium 99m tetrofosmin single photon emission computed tomography. Statistical significance was tested with univariate variance analysis and Student t tests. RESULTS: In the area of the stenosed vessel, MPRI was 1.04 +/- 0.24 before treatment and 2.18 +/- 0.57 several days afterward (P < .001). In remote areas, MPRI was 2.42 +/- 0.44. In the stent group, MPRI increased by 156%, from 0.99 +/- 0.20 before stent placement to 2.53 +/- 0.53 after (P < .001). Similarly, in the PTCA only group, MPRI increased by 72%, from 1.08 +/- 0.27 before PTCA to 1.87 +/- 0.39 after (P < .001). At follow-up in patients without recurring chest pain, MPRI was 2.14 +/- 0.37 in the area of the treated artery and 2.29 +/- 0.47 in remote areas (P = .06). CONCLUSION: The MPRI, derived from rest-stress examinations, can provide information on success of interventional procedures in stenosed coronary arteries.

Adult↗
PubMed1983

Effect of changes in perfusion pressure on renal and urinary kallikrein in the isolated perfused rat kidney.

Kallikrein activity in urine and in the renal cortex of the isolated rat kidney, perfused at constant pressure, decreased, while renal perfusate flow, glomerular filtration rate, excretion of sodium and of potassium and urine flow remained unchanged. Abrupt changes in perfusion pressure resulted in corresponding changes in renal perfusate flow, glomerular filtration rate, excretion of sodium and of potassium and urine flow. Urinary kallikrein increased little and transiently only, each time perfusion pressure was elevated. At the end of the experiments, a marked decrease in kallikrein activity in the renal tissue was found. From these results, it might be concluded that the excretion of kallikrein from the isolated perfused rat kidney resulted in a marked depletion of kallikrein stores in the kidney, probably due to an insufficient kallikrein synthesis.

Animals↗
PubMed2001

Quantitative assessment of the ischemic brain by means of perfusion-related parameters derived from perfusion CT.

BACKGROUND AND PURPOSE: Besides the delineation of hypoperfused brain tissue, the characterization of ischemia with respect to severity is of major clinical relevance, because the degree of hypoperfusion is the most critical factor in determining whether an ischemic lesion becomes an infarct or represents viable brain tissue. CT perfusion imaging yields a set of perfusion related parameters which might be useful to describe the hemodynamic status of the ischemic brain. Our objective was to determine whether measurements of the relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative time to peak (rTP) can be used to differentiate areas undergoing infarction from reversible ischemic tissue. METHODS: In 34 patients with acute hemispheric ischemic stroke <6 hours after onset, perfusion CT was used to calculate rCBF, rCBV, and rTP values from areas of ischemic cortical and subcortical gray matter. Results were obtained separately from areas of infarction and noninfarction, according to the findings on follow-up imaging studies. The efficiency of each parameter to predict tissue outcome was tested. RESULTS: There was a significant difference between infarct and peri-infarct tissue for both rCBF and rCBV but not for rTP. Threshold values of 0.48 and 0.60 for rCBF and rCBV, respectively, were found to discriminate best between areas of infarction and noninfarction, with the efficiency of the rCBV being slightly superior to that of rCBF. The prediction of tissue outcome could not be increased by using a combination of various perfusion parameters. CONCLUSIONS: The assessment of cerebral ischemia by means of perfusion parameters derived from perfusion CT provides valuable information to predict tissue outcome. Quantitative analyses of the severity of ischemic lesions should be implemented into the diagnostic management of stroke patients.

Aged↗