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At least 721 records · Page 40Linked to original sources
PubMed1996

Myocardial perfusion patterns related to thrombolysis in myocardial infarction perfusion grades after coronary angioplasty in patients with acute anterior wall myocardial infarction.

BACKGROUND: Epicardial coronary flow is occasionally reduced even after coronary intervention despite the absence of vessel obstruction in patients with acute myocardial infarction. Our aim was to clarify the cause and outcomes of radiocontrast slow filling in patients with reperfused acute anterior myocardial infarction by assessing microvascular damage with the use of myocardial contrast echocardiography (MCE) and functional outcomes. METHODS AND RESULTS: We carefully reviewed the cineangiograms of 86 patients who achieved coronary revascularization within 12 hours of the onset and underwent MCE before and soon after recanalization with the intracoronary injection of sonicated microbubbles. Antegrade coronary flow after recanalization was graded by two observers based on Thrombolysis in Myocardial Infarction (TIMI) trial flow grades. Left ventricular ejection fraction was measured on the day of infarction and 1 month later. TIMI grade 2 was observed in 18 patients (21%), and the other 68 patients manifested TIMI grade 3 after recanalization. All patients with TIMI 2 showed substantial MCE no reflow, whereas only 11 patients (16%) with TIMI 3 showed MCE no reflow. Functional improvement was worse in patients with TIMI 2 than in those with TIMI 3 (TIMI 2, 38 +/- 8% versus 40 +/- 8%, P = NS [acute versus late]; TIMI 3, 44 +/- 13% versus 55 +/- 13%, P < .001). Among patients with TIMI 3, significant functional improvement was observed only in patients with MCE reflow (MCE reflow, 46 +/- 13% versus 57 +/- 12%, P < .001; MCE no reflow, 35 +/- 11% versus 45 +/- 12%, P = NS). CONCLUSIONS: Despite no obstructive lesion of the vessel, TIMI 2 is caused by advanced microvascular damage and is a highly specific, although not sensitive, predictor of poor functional outcomes in patients with acute myocardial infarction. TIMI 3 does not necessarily indicate myocardial salvage, and detection of MCE no reflow in these patients is particularly useful for the prediction of functional outcome.

Adult↗
PubMed1999

Endothelium-dependent and -independent perfusion reserve and the effect of L-arginine on myocardial perfusion in patients with syndrome X.

BACKGROUND: Impaired vasodilatation capacity in patients with angina pectoris and a normal coronary arteriogram (syndrome X [SX]) has been reported. Most studies report on the response in epicardial vessels. This does not necessarily reflect compromised myocardial microcirculation. Lack of the NO precursor L-arginine has been suggested as a possible cause. METHODS AND RESULTS: Myocardial blood flow (MBF) was measured, using PET, at rest (MBF-rest) and during intravenous dipyridamole (MBF-DIP) in 25 women (mean age 53+/-7 years) with SX. Thirty healthy volunteers served as controls. One group (A) consisted of 15 age-matched female volunteers (54+/-10 years). The other control group consisted of 15 young healthy women (B; 24+/-5 years). In 12 SX patients, MBF-rest and MBF during cold pressor testing were also measured after infusion of L-arginine (6.7 g/min for 45 minutes). The increase in MBF after cold pressor testing was similar in the SX group compared with controls. L-arginine did not affect MBF-rest (0.83+/-0.14 versus 0.89+/-0.13 mL. g-1. min-1) or MBF after cold pressor test (0.95+/-0.10 versus 1. 03+/-0.17 mL. g-1min-1). In contrast, the hyperemic response to DIP was blunted compared with the group A controls (1.68+/-0.49 versus 2. 34+/-0.45 mL. g-1. min-1, P<0.05); this resulted in a significant reduction of the coronary flow reserve in SX patients relative to controls (2.03+/-0.53 versus 2.96+/-0.63 mL. g-1. min-1, P<0.01). CONCLUSIONS: In patients with SX, the microcirculatory response to cold, reflecting the endothelium function, is normal and unaltered by intravenous L-arginine. This suggests preserved microcirculatory endothelial function. However, a markedly attenuated hyperemic flow and flow reserve after DIP suggest a dysfunction of the adenosine-mediated endothelium-independent vasodilatation at the microcirculatory level in these patients.

Arginine↗
PubMed1988

Effects of stroma-free hemoglobin solutions on isolated perfused rabbit hearts and isolated perfused rat kidneys.

"Stroma-free" hemoglobin solutions (SFH) cause hemodynamic alterations indicative of vasoconstriction. We studied vasoconstrictor activity in isolated rabbit hearts and rat kidneys of unmodified SFH and of SFH modified by pyridoxylation or glyoxylation, with or without glutaraldehyde cross-linking. The purity and chemical composition of the solutions, all prepared by other laboratories, were not characterized by us. In isolated hearts SFH prepared by conventional methods had potent vasoconstrictor activity. Pyridoxylation or purification by ion exchange chromatography did not alter the constrictor activity. Decreased constrictor activity was observed with human SFH cross-linked by glutaraldehyde treatment, or purified by affinity chromatography, and with bovine SFH purified by ultrafiltration and preparative HPLC. In isolated kidneys modified and unmodified SFH increased renal vascular resistance and decreased glomerular filtration rate with no morphologic evidence of tubular damage.

Animals↗
PubMed1999

[Myocardial perfusion scintigraphy with 99mTC-sestamibi and gated SPECT and myocardial perfusion scintigraphy with reinjection of 201Tl at 24 hours. Are the techniques comparable?].

AIM: To compare the results obtained with 99mTc-sestamibi and gated-SPECT (gated SPECT in stress and rest) with 201Tl (stress, redistribution, and 24 hour reinjection SPECT). METHODS: Twenty patients underwent two SPECT studies, one with 201Tl and the other with 99mTc-sestamibi. RESULTS: Using 201Tl as a reference, 177 segments were considered normal, 31 viable and 32 with myocardial necrosis. The overall concordance with 99mTc-sestamibi was 84.2%. In the subgroup of defects that improved after reinjection of 201Tl, it was much less (45%), even after wall thickness and movement (55%) were analyzed. CONCLUSION: The overall concordance between 201Tl scintigraphy compared to 99mTc-sestamibi is acceptable. Correlation is low in the viable segments with 99mTc-sestamibi, even after analyzing the Gated-SPECT.

Adult↗