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Biomedical subjects

M Ragosta

Publications and source records attributed to M Ragosta.

7 recordsLinked to original sources
PubMed1992

An association between collateral blood flow and myocardial viability in patients with recent myocardial infarction.

BACKGROUND: We hypothesized that successful reperfusion of an occluded infarct-related coronary artery even late after acute myocardial infarction would result in improved regional wall motion and that such improvement might be related to the presence of collateral blood flow within the infarct bed. METHODS: We assessed regional wall motion by two-dimensional echocardiography at base line and one month after angioplasty was attempted in the occluded infarct-related artery in 43 patients who had had a myocardial infarction two days to five weeks earlier. A wall-motion score was assigned to each patient on a five-point scale (from 1 [normal function] to 5 [dyskinesia]). The percentage of the infarct bed perfused by collateral flow was assessed with myocardial contrast echocardiography. RESULTS: In the 41 patients who had abnormal wall motion at base line, improvement in function was noted in 25 (78 percent) of the 32 in whom angioplasty was successful, as compared with only 1 (11 percent) of the 9 in whom it was unsuccessful (P < 0.001). The percentage of the infarct bed supplied by collateral flow at base line was directly correlated with wall function and inversely correlated with the wall-motion score one month after successful angioplasty (r = -0.64, P < 0.001). Among the patients in whom angioplasty was successful, the 23 in whom > 50 percent of the infarct bed was supplied by collateral flow had better wall motion (P < 0.001) and greater improvement in wall motion at one month (P = 0.004) than the 9 in whom < or = 50 percent of the bed was supplied by collateral flow. The degree of improvement in function was not influenced by the length of time between the infarction and the attempted angioplasty. CONCLUSIONS: The myocardium remains viable for a prolonged period in many patients with acute infarction and an occluded infarct-related artery. Viability appears to be associated with the presence of collateral blood flow within the infarct bed.

Angioplasty, Balloon↗
PubMed1992

Myocardial thallium-201 scintigraphy for assessment of viability in patients with severe left ventricular dysfunction.

Many patients with ischemic heart disease and depressed left ventricular (LV) function have asynergic zones with sustained microcirculatory perfusion and myocardial metabolic activity that exhibit improved systolic function after coronary revascularization. The 2 predominant noninvasive techniques used to determine myocardial viability in patients with severely depressed LV function are thallium-201 (201Tl) scintigraphy and positron emission tomography (PET). Myocardial extraction of 201Tl is unaltered under experimental conditions of myocardial stunning or short-term hibernation (characterized by decreased flow and ischemic dysfunction). Akinetic or dyskinetic LV wall segments can exhibit normal or near normal 201Tl uptake as long as some residual flow is present. 201Tl scintigraphy can identify viable asynergic segments when performed on patients with severe coronary artery disease who are in the resting state. Many of these patients have initial resting defects that demonstrate delayed redistribution, or mild persistent defects that show improved perfusion and function after revascularization. There is a direct correlation between the extent of 201Tl uptake in zones of severe regional myocardial asynergy and the magnitude of improvement in resting LV ejection fraction after coronary bypass surgery. Rest 201Tl scintigraphy may help in the selection of patients with coronary artery disease and severely depressed LV function who would benefit the most from revascularization.

Animals↗
PubMed1992

Functional significance of collateral blood flow in patients with recent acute myocardial infarction. A study using myocardial contrast echocardiography.

BACKGROUND: We hypothesized that myocardial contrast echocardiography (MCE) can be used to both measure collateral blood flow as well as assess the functional significance of collaterals in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: MCE was performed in 33 patients with recent AMI (12 +/- 7 days) and an occluded infarct-related artery (IRA), both before and after attempted percutaneous transluminal coronary angioplasty (PTCA). The size of the occluded bed was defined in patients with successful PTCA by injecting contrast directly into the opened IRA and expressed as a percent of the myocardium in the short-axis view. The percent of the perfusion bed supplied by collaterals before PTCA was determined. Transit rates of the microbubbles within the collateralized regions were also measured and were expressed as a percent of the transit rates in the normal adjacent beds. Regional function within the occluded bed was assessed using echocardiography and was graded as 1 (normal) to 5 (dyskinetic). Collaterals were graded on coronary angiography as 0 (none) to 3 (abundant). The perfusion bed size was larger for the left anterior descending (LAD) than for the right (RCA) and left circumflex (LCx) coronary arteries (37 +/- 6% versus 27 +/- 12% of the myocardium, p = 0.02). The percent of the occluded bed supplied by collateral flow was greater for RCA and LCx compared with the LAD (87 +/- 30% versus 72 +/- 22%, p less than 0.01). There was poor correlation between MCE-defined percent of occluded bed supplied by collaterals and angiographic collateral grade (r = 0.13). Regions supplied by collaterals were less likely to show confluent hypoperfused zones after reperfusion compared with those not supplied by collaterals. Similarly, the percent of myocardium not perfused by either anterograde or collateral flow correlated well (r = 0.67, p less than 0.01) with peak creatine kinase levels and was more likely to be associated with Q waves. Finally, although there was poor correlation between angiographic collaterals and regional function (r = 0.20), there was a significant negative correlation between MCE-defined spatial extent of collateral flow and regional function (r = -0.57, p less than 0.01). CONCLUSION: MCE can be used to measure collateral flow in patients with recent AMI and to assess the functional significance of collaterals in these patients. This technique may be ideally suited for the assessment of collateral perfusion in patients undergoing cardiac catheterization.

Angioplasty, Balloon, Coronary↗
PubMed1992

Effect of chronic subcutaneous or intramural administration of heparin on femoral artery restenosis after balloon angioplasty in hypercholesterolemic rabbits. A quantitative angiographic and histopathological study.

BACKGROUND: Heparin is known to have antithrombotic, anticoagulant, and antiproliferative effects. We hypothesized that chronic subcutaneous and/or direct intramural administration of heparin would reduce restenosis and inhibit plaque growth after balloon angioplasty. METHODS AND RESULTS: Focal atherosclerosis was induced bilaterally in the femoral arteries of 59 rabbits by air desiccation intimal injury and a 2% cholesterol diet. After angioplasty, the rabbits were assigned to one of four treatment groups. Control arteries (n = 21) received no additional heparin. A second group of 20 arteries was treated with a porous balloon that delivered heparin (1,500 units) directly into the arterial wall. A third group (n = 29) received subcutaneous heparin (350 units.kg-1.day-1) for 28 days, and a fourth group (n = 23) was treated with subcutaneous and intramural heparin. Quantitative angiography showed a modest reduction in restenosis (defined as the change in minimal luminal diameter from immediately after angioplasty to 28 days) with subcutaneous heparin compared with control arteries (0.32 +/- 0.18 versus 0.58 +/- 0.34 mm, p < 0.01); however, luminal diameter was not improved at 28 days compared with before angioplasty. Intramural delivery of heparin by the porous balloon catheter was confirmed by use of fluoresceinated heparin in one animal. Angiographic restenosis was not reduced in arteries treated with intramural heparin versus controls (0.61 +/- 0.54 versus 0.58 +/- 0.34 mm, p = NS). Blinded planimetric analysis of histological sections showed no differences in luminal cross-sectional area narrowing by atherosclerotic plaque, in plaque area, or in plaque/media ratio at 28 days among the four treatment groups. CONCLUSIONS: Chronic subcutaneous heparin after balloon angioplasty results in a modest reduction in angiographic restenosis in this model; however, the absolute luminal diameter is not improved compared with before angioplasty, and plaque area and percent luminal narrowing by plaque were not different among the four treatment groups. Heparin can be delivered into an atherosclerotic plaque by a porous balloon, but this treatment does not reduce restenosis after angioplasty in this model.

Angioplasty, Balloon↗
PubMed1990

Characterization of nucleotidic sequences using maximum entropy techniques.

A statistical method for characterizing nucleotidic sequences based on maximum entropy techniques is presented. The method uses only codon usage tables and takes into account the length of sequences, and preserves the information contained in each codon by a punctual index. We present the methodological aspects of the analysis, showing an application relative to nucleotidic sequences of eukaryotes.

Animals↗