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Biomedical subjects

A Maseri

Publications and source records attributed to A Maseri.

At least 19 recordsLinked to original sources
PubMed1992

Von Willebrand factor, plasminogen activator inhibitor-1 and C-reactive protein are markers of thrombolytic efficacy in acute myocardial infarction.

Plasma von Willebrand factor, plasminogen activator inhibitor activity and C-reactive protein were assessed as markers of coronary recanalisation in 30 patients with acute myocardial infarction receiving tissue-type plasminogen activator (t-PA). Blood samples were taken before t-PA (time 0), 4-hourly for 24 h and daily up to 72 h. A continuous electrocardiogram was recorded in the first 24 h. Coronary arteriography was performed 90 min and 24 h after the start of t-PA. Patients with a patent infarct artery (n = 17), compared to those with occluded artery (n = 13), showed a fall in von Willebrand factor from 0 to 24 h (p = 0.001), a greater fall in plasminogen activator inhibitor from 24 to 48 h (p = 0.04) and a fall in C-reactive protein from 48 to 72 h (p = 0.002). The accuracy of these indices compared favourably with time to peak plasma MB creatine kinase and > or = 50% resolution of maximal ST-deviation on the electrocardiogram. Thus, changes in plasma von Willebrand factor, plasminogen activator inhibitor and C-reactive protein during the first 3 days of myocardial infarction are indicative of thrombolytic efficacy. Their concordant behaviour may reflect a common regulatory mechanism.

Adult↗
PubMed1992

The significance of a dipyridamole induced 99mTc-MIBI perfusion abnormality on single photon emission tomography: a quantitative validation with labelled water and positron emission tomography.

To relate technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI) uptake to regional myocardial blood flow (rMBF), 99mTc-MIBI single photon emission tomography (SPET) and H2(15)O positron emission tomography (PET) scans were obtained at rest and after dipyridamole infusion in six patients with single vessel coronary artery disease. 99mTc-MIBI and H2(15)O data sets were created for each segment perfused by the stenotic vessel and for a normal reference area, assigning regions on the SPET tomograms to comparable regions on the PET by similar transaxial image reconstructions. All patients demonstrated post-dipyridamole 99mTc-MIBI perfusion defects in the territories supplied by the stenotic arteries. Resting rMBF in these regions was slightly lower than that in the normal areas (0.82 +/- 0.05 vs 0.90 +/- 0.09 ml/g/min, P = NS). A 43% +/- 14% reduction in 99mTc-MIBI activity in the area at risk was coupled with on average a 60% +/- 9% reduction in post-dipyridamole rMBF compared with control regions (0.98 +/- 0.08 vs 2.52 +/- 0.51 ml/g/min, P < 0.001). Thus, SPET assessment of 99mTc-MIBI uptake tends to underestimate the perfusion contrast between areas with normal and areas with low coronary vasodilatory reserve when compared to PET. However, these findings may still not affect the clinical usefulness of 99mTc-MIBI and more extensive studies are required to confirm these results in the clinical environment.

Contrast Media↗
PubMed1992

Preangioplasty complicated coronary stenosis morphology as a predictor of restenosis.

To assess whether complicated preangioplasty coronary stenosis morphology is associated with restenosis, 41 patients (47 stenoses) who underwent repeat angiography 6 to 8 months after percutaneous transluminal coronary angioplasty (PTCA) were studied. Stenosis diameter and morphology were assessed by computerized quantitative coronary angiography before and immediately after PTCA and at follow-up angiography. Before PTCA 18 stenoses were concentric (symmetric narrowings with smooth borders), 12 were eccentric (asymmetric narrowings with smooth borders), and 17 were complicated (asymmetric with rough borders and overhanging edges). Restenosis occurred in 18 lesions: two (11%) concentric, four (33%) eccentric, and 12 (70%) complicated (p less than 0.05), whereas 29 lesions remained unchanged. Stenosis diameter before and immediately after PTCA was not significantly different in the 18 patients with and the 23 patients without restenosis. Follow-up angiograms showed that 11 (61%) stenoses in the group with restenosis and 18 (63%) in the group without restenosis had morphology similar to that before PTCA. Restenosis occurred in seven (30%) patients who initially had chronic stable angina and in 11 (61%) who were first seen with unstable angina (p less than 0.05). In patients with stable angina 1 of 13 concentric stenoses, two of eight eccentric stenoses, and four of five complicated lesions restenosed. In patients with unstable angina one of five concentric, two of four eccentric, and 8 of 12 complicated lesions had restenosis. Stenoses that were complicated before PTCA tended to adopt an irregular morphology if they recurred, whereas concentric stenoses rarely occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A combination of electrocardiographic methods represents a further step toward the noninvasive identification of patients with syndrome X.

Identification of patients with angina but normal coronary arteriograms (syndrome X) using noninvasive means would be desirable. The ability of four established exercise electrocardiographic methods to identify angina patients with and without coronary artery disease was compared with that of a method based on a combination of the above (combined method). A treadmill score, a multivariate method, the ST segment recovery loop, the ST/heart rate adjustment, and the combined method were applied to 112 patients who had typical exertional angina and positive exercise tests (greater than 1 mm ST segment depression); 90 had documented coronary artery disease and 22 had syndrome X. The combined method and the treadmill score had a significantly higher diagnostic accuracy (both 81%, as 91 of the 112 patients were correctly identified by both methods) than the multivariate (66%) and ST segment recovery loop (64%) methods (p less than 0.05). The ST/heart rate adjustment had a lower sensitivity for syndrome X than any other method (1 of 22). Thus methods that involve the assessment of both ST and non ST segment variables have greater accuracy in separating syndrome X and coronary artery disease patients than methods relying more heavily on ST segment changes.

Adrenergic beta-Antagonists↗
PubMed1992

Dipyridamole vasodilator response after human orthotopic heart transplantation: quantification by oxygen-15-labeled water and positron emission tomography.

To assess coronary vasodilator reserve after orthotopic heart transplantation, regional myocardial perfusion was measured with oxygen-15-labeled water and dynamic positron emission tomography in 14 cardiac allograft recipients who were not experiencing rejection and who had no angiographic evidence of epicardial coronary sclerosis 15 to 73 months (mean +/- SD 43 +/- 19) after transplantation (group I). Twelve normal men with an average age of 31 years (group II) served as a control group. Regional perfusion was measured at rest and after the intravenous administration of 0.6 mg/kg body weight of dipyridamole. Rest regional myocardial blood flow was homogeneously distributed throughout the left ventricle and was significantly higher in transplant recipients (mean 1.16 +/- 0.26 ml/g per min [range 0.8 to 1.73] than in normal subjects (mean 0.85 +/- 0.13 ml/g per min [range 0.57 to 0.99]; p = 0.001) as was rest heart rate-systolic blood pressure product (rate-pressure product 11,255 +/- 2,540 vs. 7,073 +/- 1,306; p less than 0.001). After dipyridamole, perfusion in the transplant recipients was homogeneous and slightly lower (2.73 +/- 1.03 vs. 3.40 +/- 1.09 ml/g per min; p = NS), whereas rate-pressure product was slightly higher (12,179 +/- 2,266 vs. 10,885 +/- 1,895; p = NS) than the value in normal subjects. Dipyridamole vasodilator response (dipyridamole/rest myocardial blood flow) ranged from 1.23 to 4.92 (mean 2.50 +/- 1.13) in group I and from 2.65 to 5.45 (3.97 +/- 0.89) in group II (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Relation between stimulation site of cardiac afferent nerves by adenosine and distribution of cardiac pain: results of a study in patients with stable angina.

OBJECTIVES: The purpose of this study was to establish whether stimulation of cardiac sensory receptors in different myocardial regions results in different distributions of cardiac pain. BACKGROUND: Previous studies have shown that adenosine provokes cardiac pain through stimulation of sensory receptors in the absence of myocardial ischemia. In this study adenosine was used to obtain a regional stimulation of cardiac sensory receptors. METHODS: Increasing doses of adenosine (0.25, 0.5 and 1 mg/min) were selectively infused into the right and then into the left coronary artery in 26 patients with stable angina. RESULTS: No patient developed ischemic electrocardiographic changes during either adenosine infusion. Eighteen patients experienced cardiac pain during both infusions. Despite the stimulation of sensory receptors in different myocardial regions, 13 patients experienced cardiac pain in the same body area. Adenosine-induced pain was always similar to the anginal pain. By contrast, the remaining five patients experienced adenosine-induced cardiac pain in different body areas. In two of these patients, the distribution of anginal pain was similar to that experienced during one of the two adenosine infusions. In the remaining three patients, the distribution of anginal pain was similar to that experienced during adenosine infusion into the right coronary artery during some anginal episodes and to that experienced during adenosine infusion into the left coronary artery during other episodes. CONCLUSIONS: During stimulation by adenosine of sensory receptors in different myocardial regions, the majority of patients experience cardiac pain in the same body area; only a few experience pain in different areas. These differences might be caused by different organizations of the ascending neural pathways to the cortex. Our results suggest that in the same patient different distributions of pain during anginal attacks are probably due to ischemia in different myocardial regions.

Adenosine↗
PubMed1992

WEB 2086 inhibits neutrophil dependent increases in coronary resistance in blood perfused rabbit heart.

OBJECTIVE: The aim was to investigate the mechanism of the pressor action of the chemotactic peptide formyl-methionyl-leucyl-phenylalanine in the blood perfused Langendorff preparation of the isolated rabbit heart; and in particular to establish whether the response was dependent on the presence of neutrophils and whether the release of platelet activating factor contributed to the pressor effect. METHODS: An isolated rabbit heart was perfused with blood from an anesthetised support rabbit. Formyl-methionyl-leucyl-phenylalanine was injected intra-arterially proximal to the isolated heart and measures of cardiac performance recorded. In some experiments the support animal was depleted of neutrophils by pretreatment with mechlorethamine while in others the specific platelet activating factor receptor antagonist WEB 2086 was given to the support animal before formyl-methionyl-leucyl-phenylalanine. Differential blood cell counts were determined throughout the course of each experiment. Each heart was examined histologically after the experiment. RESULTS: Formyl-methionyl-leucyl-phenylalanine caused a significant rise in perfusion pressure which was virtually abolished by leucocyte depletion of the support animal. The response could also be reduced by about 80% with intravenous WEB 2086. Histological examination of the perfused hearts showed that the number of accumulated neutrophils was very variable and not correlated with the rise in perfusion pressure. There was no significant difference between control hearts and those receiving WEB 2086. CONCLUSIONS: The results confirm previous reports that the response to formyl-methionyl-leucyl-phenylalanine is neutrophil dependent and show that this model of a blood perfused heart can be used successfully to examine the response to a leucocyte dependent stimulus. The results also suggest that the response to formyl-methionyl-leucyl-phenylalanine may not only be due to physical obstruction of the coronary circulation or "neutrophil plugging", but may also be due to the release of platelet activating factor.

Animals↗
PubMed1992

Variant angina pectoris. Role of coronary spasm in the development of fixed coronary obstructions.

BACKGROUND: It has been suggested that recurring coronary artery spasm may lead to the development of fixed atherosclerotic coronary obstructions. METHODS AND RESULTS: We studied 10 patients with typical Prinzmetal's variant angina in whom the disease remained active for years and in whom occlusive coronary spasm occurred reproducibly at the same arterial site during repeat coronary arteriography (25 +/- 12 months after initial angiography). At initial evaluation, four patients had significant (greater than or equal to 50% fixed coronary diameter reduction) one-vessel coronary artery disease, and six had nonsignificant disease. Spasm developed at stenotic sites (20-65% diameter reduction) in nine patients and at an angiographically normal site in one patient. Progression of coronary disease was assessed in 62 segments: 10 spastic (of which nine were stenotic) and 52 nonspastic (eight stenotic and 44 angiographically normal), using computerized arteriography. Mean diameters (millimeters) of spastic segments, nonspastic stenoses, and angiographically normal nonspastic segments were not significantly different at first and second arteriograms (1.52 +/- 0.14 versus 1.43 +/- 0.21, 1.32 +/- 0.17 versus 1.12 +/- 0.23, and 2.40 +/- 0.12 versus 2.42 +/- 0.12, respectively). Stenosis progression (from 65% diameter reduction to total occlusion) occurred in one patient at a spastic site and in two at nonspastic sites (from 34% to 65% and from 84% to 100%). Complicated stenoses suggestive of plaque fissuring were not observed during the study. CONCLUSIONS: In patients with chronic Prinzmetal's variant angina without myocardial infarction, stenosis progression was not frequently observed at spastic sites despite the recurrence of focal coronary spasm over relatively long periods of time.

Adult↗
PubMed1992

Effect of ketanserin on proximal and distal coronary constrictor responses to intracoronary infusion of serotonin in patients with stable angina, patients with variant angina, and control patients.

BACKGROUND: Serotonin, released by aggregating platelets, may contribute to or cause myocardial ischemia by constricting epicardial vessels. Experimental studies suggest that this constriction is mediated by two distinct serotonin receptor subtypes: 5-hydroxytryptamine1-like (S1-like) and 5-hydroxytryptamine2 (S2). METHODS AND RESULTS: To determine the relative contribution of S1-like and S2 receptors to the vasoconstrictor effects of serotonin, we studied the effect of ketanserin (0.75 mg, intracoronary), a selective S2 receptor antagonist, on the constrictor response of human coronary vessels to intracoronary infusions of serotonin. In control patients (n = 7), serotonin (10(-4) mol/l) caused significant (p less than 0.05) constriction only in distal segments, which was significantly (p less than 0.05) inhibited by ketanserin. In stable angina patients (n = 8), serotonin (10(-4) mol/l) caused significant constriction in proximal (p less than 0.01) and distal (p less than 0.01) segments, which was significantly inhibited by ketanserin in proximal (p less than 0.05) but not distal (p = 0.30) segments. In patients with variant angina (n = 3), epicardial occlusion at the site of preexisting stenoses in proximal locations occurred at infused concentrations of 10(-6) (one patient) or 10(-5) (two patients) mol/l. The infusion of the same concentration of serotonin after ketanserin again caused epicardial occlusion. CONCLUSIONS: Our results suggest that functionally important S1-like receptors that mediate vasoconstriction exist in the epicardial vessels of patients with stable or variant angina. Their activation, either at hyperreactive sites in patients with variant angina or in the distal epicardial vessels of patients with chronic stable angina, may contribute to or cause myocardial ischemia when serotonin is released after the intracoronary activation of platelets.

Adult↗
PubMed1992

Preoperative prediction of the outcome of coronary revascularization using positron emission tomography.

BACKGROUND: Previous assessments of myocardial viability using positron emission tomography (PET) relied on demonstration of glucose metabolism in hypoperfused asynergic segments using the glucose analogue [18F]2-fluoro-2-deoxyglucose (FDG). Recently, it was shown that myocardial viability could be assessed by calculating the water-perfusable tissue index (PTI) for the asynergic region. PTI represents the proportion of the myocardium that is capable of rapid transsarcolemmal exchange of water and thus perfusable by water. The aim of the present study was to assess myocardial viability by PET using PTI in patients undergoing coronary revascularization. METHODS AND RESULTS: Twelve patients with chronic coronary artery disease and previous myocardial infarction were studied. Analysis of transmission (tissue density) and 15O-labeled carbon monoxide (blood pool), and 15O-labeled water (myocardial blood flow [MBF]) emission PET data enabled the simultaneous quantification of MBF (ml.min-1.g perfusable tissue-1) and PTI (gram of perfusable tissue per gram of total anatomic tissue). In addition, PET imaging with FDG after 75-g oral glucose load was performed in eight patients. Preoperative echocardiography identified 33 hypocontractile and 26 control segments. Follow-up echocardiography performed 3 to 5 months later demonstrated 26 of 33 segments with improved wall motion (recovery) and seven of 33 segments without improvement (nonrecovery). MBF in the control segments (0.97 +/- 0.22 ml.min-1.g perfusable tissue-1) was significantly higher (p < 0.001) than in both the recovery (0.73 +/- 0.18 ml.min-1.g perfusable tissue-1) and the nonrecovery (0.45 +/- 0.11 ml.min-1.g perfusable tissue-1) segments. PTI in the recovery regions (0.99 +/- 0.15) was > or = 0.7 in all cases and slightly less than in control regions (1.10 +/- 0.15, p < 0.02). FDG uptake in these regions was 92 +/- 17% (n = 13) of the uptake in control segments with normal wall motion. In the nonrecovery group, PTI was 0.62 +/- 0.06 (p < 0.02 versus control and recovery) and always < 0.7. In the one patient in whom a comparison with metabolic imaging was made, FDG uptake was 46% of the uptake in a reference region with normal wall motion. CONCLUSIONS: These data showed that contractile recovery occurred only in segments where PTI was > or = 0.7, suggesting that > or = 70% of myocardial tissue in a given asynergic segment should be perfusable by water to enable contractile recovery. There was good agreement between the PTI and FDG methods for predicting improvements in regional wall motion after revascularization. Although further studies should be performed in a larger patient group, the preliminary results are promising and suggest that PTI may be a good predictor of contractile recovery after coronary revascularization.

Angioplasty, Balloon, Coronary↗
PubMed1992

Cultured rat aortic vascular smooth muscle cells digest naturally produced extracellular matrix. Involvement of plasminogen-dependent and plasminogen-independent pathways.

Vascular smooth muscle (VSM) cell migration and proliferation play a major role in the development of atherosclerotic lesions, graft occlusion, and restenosis after angioplasty. Cell migration implies the digestion of the surrounding extracellular matrix. Cell-associated proteolysis has been extensively studied in neoplastic and inflammatory cells, but very little is known about the proteolytic properties of VSM. We have evaluated the ability of rat cultured VSM cells to solubilize [3H]amino acid-labeled extracellular matrices produced by bovine VSM. When plated at a density of 30,000 cells per well in 24 multiwell plates, VSM cells were able to solubilize 63.3 +/- 7.0% of the extracellular matrix after 10 days in culture. Extracellular matrix digestion occurred also when the cells were cultured in plasminogen-depleted serum but was higher in the presence of 10 micrograms/ml purified plasminogen (net percent digestion after the subtraction of the appropriate control, 8.6 +/- 3.0% versus 21.2 +/- 3.5% after 3 days in culture, p less than 0.005, respectively). The involvement of other enzymes in addition to plasmin is confirmed by the ability of VSM cells to degrade extracellular matrices from which the plasmin-sensitive component was removed with plasmin pretreatment. Rat VSM cells were able to solubilize 52.3 +/- 2.0% of this residual extracellular matrix-associated radioactivity after 6 days in culture versus 26.1 +/- 1.5% in the control dishes (p less than 0.01, n = 5). Cell contact was required for extracellular matrix degradation: cell-conditioned medium did not have any effect on extracellular matrix digestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Abnormal coronary vasomotion in ischemic heart disease.

Myocardial ischemia has long been thought to be caused by only critical arteriosclerotic plaques, which are the most obvious single denominators of ischemic cardiac syndromes. The author argues that just because other transient and dynamic mechanisms are more elusive than atherosclerotic plaques, we should not presume them to be unimportant. He reviews the work of his group and others, which suggests that dilation and constriction can occur at the site of coronary artery stenoses and in distal coronary vessels. Clinical and angiographic findings and the possible pathophysiological causes of vasomotor dysfunction that may modulate residual coronary flow in patients with chronic stable, unstable, and variant angina, and syndrome X are reviewed. Only when these mechanisms are more fully understood will it be possible to develop specific therapy.

Angina Pectoris, Variant↗