Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to determine the changes in cardiac interstitial fluid (ISF) purine metabolites during 90 min of regional myocardial ischemia. To collect ISF metabolites and measure local coronary blood flow (CBF), cardiac microdialysis probes were implanted into the left anterior descending artery (LAD) and left circumflex artery (LC) perfused myocardium of chloralose-urethane anesthetized dogs (n = 7). Regional ventricular wall thickness was measured in the LAD and LC perfused regions with sonomicrometric crystals, using systolic wall thickening (SWT) as an index of regional ventricular function. Regional myocardial ischemia, produced by occlusion of the LAD, resulted in a decrease in CBF (hydrogen clearance) from 77.3 +/- 12.4 to 10.9 +/- 4.4 ml/min/100 g (P less than 0.05), and systolic wall thinning (control SWT = 15.5 +/- 2.2%; ischemic SWT = -6.8 +/- 1.7%). ISF adenosine was transiently elevated in the ischemic region, obtaining a maximum sixfold increase after 15 min of ischemia. Inosine, hypoxanthine, and to a lesser extent xanthine, composed the majority of metabolites which accumulated in the ISF of the ischemic region, accounting for greater than 95% of the total purine metabolites in the ISF after 20 min of ischemia. Despite the marked increase in ISF inosine, hypoxanthine, and xanthine levels, ISF uric acid levels did not increase in the ischemic region. Although CBF and SWT did not change in the nonischemic LC perfused area, there were small transient increases (two- to fourfold) in ISF adenosine, inosine, and hypoxanthine levels. In summary, these data demonstrate that purine metabolites accumulate rapidly in the ISF during myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Interstitial purine metabolites during regional myocardial ischemia. 235 25

To explore relationship between hypertrophy of left ventricle and its shape, blood supply and calcium turnover, the study enrolled 105 male patients with ischemic heart disease or those suspected of its presence. All patients underwent contrast coronary ventriculography, M-mode echocardiography and sectorial scanning. Moderately limited myocardial blood supply was found to be a factor, stimulating its local hypertrophy. In the event of severely impaired blood supply, no substantial myocardial hypertrophy is detectable in corresponding regions, while dynamic observation not infrequently reveals thinning of the wall. Patients with intact coronary arteries, and having more elongated shape of left ventricular cavity, demonstrate larger thickness of walls along the long axis, that is probably due to dependence of intramyocardial tension on the radius of the wall curvature. While performing ventriculography in the patients with hypertrophic myocardium, disclosed elevated level of calcium in the blood and enhanced calcium uptake by cardiac muscle versus patients without left ventricular hypertrophy.
 ...
PMID:Significance of left ventricular shape, its blood supply and calcium turnover for evolving myocardial hypertrophy. 252 3

Gated magnetic resonance imaging (MRI) provides excellent anatomic evaluation of the heart, but its capability for assessing cardiac physiology is less clear. Accordingly, regional left ventricular (LV) wall thickening was evaluated by multiphasic transverse images in 37 patients with a variety of myocardial diseases and in 9 normal subjects. Angiography and 2-dimensional echocardiography (2-D echo) were used for comparison. End-diastolic and end-systolic wall thickness, absolute systolic wall thickening and percent systolic wall thickening were determined in 7 regions. Mean systolic wall thickening in normal subjects was not significantly different among the regions. However, there was considerable individual variation in wall thickening, ranging from 18 to 100%. Patients with LV hypertrophy (n = 4), amyloid cardiomyopathy (n = 1), constrictive pericarditis (n = 5), and hypertrophic cardiomyopathy (n = 3) had absolute and percent systolic wall thickening within normal limits. Infarcted segments in patients with ischemic heart disease (n = 17) had reduced absolute and percent systolic wall thickening, often combined with diastolic wall thinning, whereas mean percent systolic wall thickening in adjacent normal myocardial regions was higher than in normal volunteers (p less than 0.001). In patients with coronary artery disease, MRI had a sensitivity and specificity of 93% in detecting regional wall motion abnormalities. Because sagittal images were not acquired, inferior wall motion abnormalities were not assessed by MRI due to parallel wall sectioning in transverse images.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Regional left ventricular wall thickening by magnetic resonance imaging: evaluation in normal persons and patients with global and regional dysfunction. 294 75

Proton NMR imaging of myocardial ischemia without infarction requires the use of paramagnetic contrast agents. Even during the first few hours of infarction, imaging without contrast enhancement reveals only slight natural image contrast. Myocardial infarction, however, is much more readily detected during the first few days and weeks post coronary occlusion; this is due to a marked elevation in T2 during this time period. Chronic infarction, several months after the acute event, does not demonstrate altered signal intensity, but can be detected by visualizing myocardial wall thinning and aneurysm formation. Information regarding high energy phosphate metabolism can be acquired in vivo in ischemic animal preparations; preliminary data has demonstrated that it is possible to acquire similar information noninvasively in man. Development of this technique will eventually permit the study of pharmacological and mechanical interventions aimed at preserving myocardium in the ischemic heart. Exogenous labelling of myocardial tissue with carbon-13 permits the study of the effects of substrates on cellular metabolism. Ultimately, the technique of chemical shift imaging will provide a method of spatially resolving valuable metabolic information in the form of an NMR image. Eventually, with the gradual development of NMR technology, imaging and spectroscopy will become truly important clinical tools in the investigation of ischemic heart disease in man.
 ...
PMID:Evaluation of myocardial ischemia and infarction by nuclear magnetic resonance techniques. 328 14

To assess the usefulness of X-ray computed tomography (CT) and magnetic resonance imaging (MRI) in detecting and evaluating ischemic heart disease, conventional and enhanced CT were performed for 180 patients (150 with transmural infarction, 12 with subendocardial infarction, and 18 with angina pectoris). MRI examinations were performed for 38 patients (31 with transmural infarction, three with subendocardial infarction, and four with angina pectoris). With enhanced CT, two findings in the myocardium were direct evidence of myocardial infarction: 1. filling defects on the early scans, and 2. late enhancement of the myocardium on the delayed scans. The former were observed mainly at the sites of recent anterior myocardial infarction and the latter were seen in about half of the patients with recent and remote anterior myocardial infarctions. However, these findings were inadequately imaged in patients with inferoposterior infarction and subendocardial infarction. Among 137 patients with transmural infarction, enhanced CT revealed left ventricular aneurysms in 51 (37%) and ventricular thrombi in 26 (19%). ECG-gated MRI apparatus having a superconducting magnetic operating at 0.25 Tesla was used, and data for this study were collected using the single-slice spin echo technique. In eight of nine patients with acute myocardial infarction, gated MRI demonstrated the infarcted myocardium as regions of high signal intensity relative to that of the adjacent normal myocardium. Such a difference in MRI signal intensity was scarcely recognized in the chronic stage of myocardial infarction, but the indirect findings of infarction, such as regional wall thinning, wall motion disturbances, left ventricular aneurysms, and ventricular thrombi were easily detected using MRI. No characteristic finding was obtained by CT or MRI in patients with angina pectoris.
 ...
PMID:[Diagnostic evaluation of ischemic heart disease by X-ray computed tomography and magnetic resonance imaging]. 342 26

In vivo gated magnetic resonance (MR) imaging was performed in 12 dogs immediately after occlusion of the left anterior descending coronary artery and serially up to 5 hours and again between 4 and 14 days. This was done to evaluate the appearance of acute myocardial infarcts and to determine how soon after coronary artery occlusion MR imaging can demonstrate the site of acute myocardial ischemia. In nine dogs with postmortem evidence of myocardial infarction, regional increase of signal intensity of the myocardium was present by 3 hours after coronary artery occlusion and conformed to the site of myocardial infarct found at autopsy. The signal intensity on T2-weighted images of the infarcted myocardium was significantly greater than that of normal myocardium at 3, 4, and 5 hours after occlusion. The T2 (spin-spin) relaxation time was significantly prolonged in the region of myocardial infarct at 3, 4, and 5 hours postocclusion compared with normal myocardium. Myocardial wall thinning and increased intracavitary flow signal were found in six dogs with comparable pre- and postocclusion images in late systole.
 ...
PMID:Early-phase myocardial infarction: evaluation by MR imaging. 370 48

A continuing theme in our laboratory has been the use of echocardiographically-measured systolic myocardial wall thickening to demonstrate and evaluate the consequences of regional myocardial ischemia. This presentation focuses on two areas: the immediate mechanical consequences of induced myocardial ischemia in two experimental models: canine and human; the correlation between persistent regional myocardial dysfunction and morphologic infarction after sequences of coronary artery occlusion and reperfusion. Many experiments using animal models have demonstrated that acute myocardial ischemia produces almost immediate replacement of normal systolic myocardial wall thickening by systolic thinning. Less is known about the immediate mechanical response of human myocardium to acute ischemia. This was studied in 5 open-chest humans undergoing various cardiac operations. Wall thickening was continuously displayed by a 7 MHz M-mode echocardiographic transducer coupled to the epicardium by suction to maintain constant position. Coronary flow velocity was displayed by a pulsed Doppler device coupled to an epicardial coronary artery by suction. Ischemia was induced by the surgeon who manually occluded the coronary artery with a soft-tipped Kitner dissector or vascular forceps for 30 seconds. It was found that cessation of coronary flow was accompanied by reductions in normal systolic thickening but systolic thinning or expansion only rarely occurred. In contrast, when the identical techniques were used in 5 dogs, systolic thinning always occurred immediately after coronary arterial occlusion. This suggests that there are important species differences between canine and human myocardium in the immediate mechanical response to myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Transient myocardial ischemia: experimental echocardiographic demonstration and evaluation of myocardial contraction abnormalities. 375 77

The usefulness of coronal and sagittal sections of the cardiovascular system by magnetic resonance imaging was evaluated. Coronal, sagittal and transverse spin echo scans using ECG-non-gating and gating during systole and diastole were performed for five normal volunteers, 91 with heart diseases (25 valvular disease, 28 ischemic heart disease, 14 cardiomyopathies, 14 congenital malformations, four pericardial diseases, and six others) and 32 patients with aortic abnormalities (17 aneurysms, 10 dissections and five others) using a 2.5 KGauss unit. Cardiac gating necessitated six to eight min per scan, but it was mandatory to obtain clear images of the details. On the other hand, in most of the aortic abnormalities, diagnostic images were obtained by the ECG-non-gating technique which required only about 2.5 min per scan. Coronal and sagittal sections were useful for estimating the entire shape and size of each cardiac chamber and intracardiac thrombi, the extent of postinfarctional wall thinning and cardiac aneurysms, and hypertrophy or narrowing of both the ventricular outflow tracts and apex. These planes were particularly useful, and more contributory than transverse planes for detecting inferior myocardial damage such as infarction. A few coronal and sagittal scans were sufficient to diagnose extensive lesions of the aorta, such as atherosclerosis, dissections and the aortitis syndrome. Local lesions such as coarctation, supravalvular aortic stenosis, annulo-aortic ectasia and aneurysm, especially those originating in the inferior wall of the aortic arch were easily discovered. Since the main arteries, such as the innominate, left common carotid, left subclavian and renal arteries, were clearly demonstrated by coronal images, coronal scans were considered more useful than transverse ones for observing the relationship between these arteries and dissections or aneurysms of the arch and of the abdominal aorta.
 ...
PMID:[Magnetic resonance imaging of cardiovascular diseases: advantages of coronal and sagittal planes]. 384 98

In view of clinical interest in the efficacy of beta-adrenergic blockade during acute myocardial infarction (AMI), we have determined the long-term effect of therapy on scar formation after experimental myocardial ischemia. Intact anesthetized dogs underwent acute occlusion of the left anterior descending coronary artery, by means of a balloon catheter, which permitted monitoring of the aortic-peripheral coronary artery pressure gradient during the 4-hour period of balloon inflation. Practolol administration was begun 15 minutes after the onset of ischemia in group A. Control animals (group B) received procainamide to approximate the antiarrhythmic action of beta blockade. Only group A exhibited significant reduction in the ST segments during acute ischemia. Chronic therapy was maintained for 1 month and the mature scar formed in the myocardium was assessed after 4 months. The extent of subendocardial scar was similar in both groups but subepicardial scar formation was significantly less in group A. There was also a significant decrease in the percentage of total myocardium involved with scar in this treatment group. Although thinning of the left ventricular wall was similar for both groups in the central scar region, this process was significantly reduced at the lateral margin in group A. Thus, specific beta-receptor blockade during acute myocardial ischemia and sustained during the repair process can result in a reduced quantity and altered distribution of mature scar.
 ...
PMID:Effects of beta-adrenergic inhibition on scar formation after myocardial infarction. 614 52

Coronary heart disease can be detected via echocardiography, if myocardial ischemia or infarction are present leading to segmental abnormalities of left ventricular function. The capability to demonstrate these regional changes is limited as far as TM echocardiography is concerned, whereas 2D echocardiography is more reliable. For this purpose, cross-sectional imaging of all segments in several planes is necessary. The complex mosaic of findings obtained in this way is best documented by means of a segmental scheme of representative sections. Infarct size then can be estimated by a segmental score. Depressed wall motion and systolic wall thickening are used as criteria for ischaemia and infarction. In the chronic phase, morphological changes can be identified additionally: Thinning, expansion and increased reflectivity of the infarcted areas. In acute myocardial infarction, echocardiography is mainly used if the course is complicated, in the chronic phase, if ECG-changes are questionable, or to evaluate residual ventricular function after large infarcts. Even the TM echocardiogram reliably estimates the ventricular damage caused by the infarct in the chronic phase.
 ...
PMID:[Echocardiography in coronary heart disease]. 623 Jul 19


<< Previous 1 2 3 4 5 6 Next >>