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Biomedical subjects

Andrew M Kates

Publications and source records attributed to Andrew M Kates.

6 recordsLinked to original sources
PubMed2006

Possible paradoxical embolism as a rare cause for an acute myocardial infarction.

Paradoxical embolus is a rare entity and it has been incriminated as a cause of both cryptogenic strokes and myocardial infarctions (MI). Herein, we present a case of a patient diagnosed with a pulmonary embolism 1 week prior who now presented with an acute MI. Subsequent evaluation revealed a patent foramen ovale and a large thrombus in the right pulmonary artery. It was presumed that the etiology of her infarct was due to paradoxical embolus. The management of the patient is discussed and the literature is reviewed.

Aged↗
PubMed2005

The bicuspid aortic valve.

The bicuspid aortic valve affects 1 to 2% of the population and may be complicated by aortic stenosis or aortic insufficiency and infective endocarditis. The bicuspid aortic valve is associated with abnormalities of the aortic wall such as coarctation of the aorta, aortic dissection, and aortic aneurysm. Most patients with a bicuspid aortic valve will develop some complication during life. Individuals with a bicuspid valve may be unaware of its presence and are at risk for unsuspected complications. Aortic wall abnormalities associated with bicuspid aortic valve are due to cystic medial necrosis. This process is associated with increased metalloproteinase activity and apoptosis of vascular smooth muscle cells. The clinical correlates of aortopathy in the bicuspid aortic valve include significant enlargement of the ascending aorta with aneurysm formation and dissection. This process continues after valve replacement. The person with bicuspid aortic valve requires continuous surveillance to treat associated lesions and prevent complications.

Aortic Valve↗
PubMed2004

Noninvasive, quantitative assessment of left ventricular function in ischemic cardiomyopathy.

BACKGROUND: Coronary artery disease characteristically impacts left ventricular (LV) function on a regional basis, although ultimately global function may be affected as well. Echocardiography is commonly clinically used for the assessment of regional function; however, it is only semiquantitative and in its current iteration is only two-dimensional in nature. Magnetic resonance imaging (MRI) with tissue tagging offers the possibility for noninvasive, three-dimensional (3D) assessment of transmural and segmental left ventricular strain and, thereby, function. Accordingly, we have explored methodologies to accurately and quantitatively characterize regional systolic function in three dimensions in patients with ischemic heart disease using MRI. MATERIALS AND METHODS: MRI radiofrequency tissue tagging was performed at rest and during dobutamine administration (10 mg/kg/min) on 10 normal volunteers (age: 26 +/- 6) and 8 patients with severe ischemic cardiomyopathy (age: 60 +/- 5, EF 26 +/- 11%). Three-dimensional global and regional systolic strain calculations were made based on 3D myocardial point displacements and compared with conventional measures. RESULTS: Global left ventricular strains were significantly decreased in ischemic patients at rest (0.14 +/- 0.04 versus 0.25 +/- 0.02, P < 0.001) and with dobutamine (0.14 +/- 0.03 versus 0.29 +/- 0.03, P < 0.001). In the regional analysis (216 LV wall segments) this methodology accurately differentiated normal from abnormally contracting regions. CONCLUSIONS: Noninvasive dobutamine MRI tissue tagging with calculation of 3D regional strains has significant promise as a clinical tool which is capable of the identification, quantification, and display of regionally varying ventricular function.

Aged↗
PubMed2003

Impact of aging on myocardial metabolic response to dobutamine.

In humans, under resting conditions there is an age-related decrease in myocardial fatty acid utilization (MFAU) and oxidation (MFAO) and a relative increase in myocardial glucose utilization (MGU). The impact of age on an individual's myocardial metabolic response to catecholamines is not well defined. Sixteen younger (mean age, 26 +/- 5 yr) and 14 older (mean age, 69 +/- 4 yr) volunteers underwent positron emission tomography to measure myocardial blood flow, myocardial oxygen consumption (M.VO2), MFAU, MFAO, and MGU both under resting conditions and during dobutamine infusion. In response to dobutamine administration, the rate-pressure product, myocardial blood flow, and M.VO2 measurements increased by similar amounts in both groups. No age-related differences were noted in the responses of plasma insulin, glucose, fatty acid, or lactate levels to dobutamine. With dobutamine infusion, MFAU and MFAO increased by a similar extent in both younger and older volunteers (age/dobutamine interactions, P = 0.62 and 0.75, respectively). In contrast, MGU increased with dobutamine administration in the younger (from 149 +/- 71 to 209 +/- 78 nmol.g(-1).min(-1); P = 0.04) but not in the older (from 235 +/- 147 to 176 +/- 84 nmol.g(-1).min(-1); P = 0.23; age/dobutamine interaction, P = 0.03) group. With dobutamine infusion, hearts in both younger and older volunteers responded by increasing their MFAU and MFAO values. Whereas younger hearts also responded with an increase in MGU, older hearts did not. Although the clinical significance of these findings awaits further study, these results may partially explain the impaired contractile reserve and the increased incidence of cardiovascular disease in older individuals.

Adrenergic beta-Agonists↗
PubMed2003

Impact of aging on substrate metabolism by the human heart.

BACKGROUND: Results of studies in experimental animals have shown that, with age, myocardial fatty acid metabolism decreases, and glucose metabolism increases. Whether similar changes occur in humans is unknown. METHODS: Seventeen healthy younger normal volunteers (six males, 26 +/- 5 years) and 19 healthy older volunteers (nine males, 67 +/- 5 years) underwent positron emission tomography (PET) under resting conditions in the fasted state. Myocardial blood flow (MBF), myocardial oxygen consumption (MVO(2)), myocardial fatty acid utilization (MFAU) and oxidation (MFAO), and myocardial glucose utilization (MGU) were quantified by PET with (15)O-water, (11)C-acetate, (11)C-palmitate, and(11)C-glucose, respectively. RESULTS: Although MBF was similar between the groups, MVO(2) was higher in the older subjects (5.6 +/- 1.6 micromol/g/min) compared with younger subjects (4.6 +/- 1.0 micromol/g/min, p < 0.04). Rates of MFAU and MFAO (corrected for MVO(2)) were significantly lower in older subjects than in younger subjects (MFAU/MVO(2): 35 +/- 10 vs. 51 +/- 20 nmol free fatty acids (FFA)/nmol O(2) x 10(-3), p < 0.005, and MFAO/MVO(2): 33 +/- 10 vs. 48 +/- 18 nmol FFA/nmol O(2) x 10(-3), p < 0.004). In contrast, the rates of MGU corrected for MVO(2) did not differ between the groups. CONCLUSIONS: With aging, humans exhibit a decline in MFAU and MFAO. Although absolute rates of MGU do not increase, by virtue of the decline in MFAU there is likely an increase in relative contribution of MGU to substrate metabolism. The clinical significance of this metabolic switch awaits further study.

Adult↗