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Biomedical subjects

J L Bedynek

Publications and source records attributed to J L Bedynek.

At least 19 recordsLinked to original sources
PubMed2000

Tricuspid aortic valve with partial commissural fusion: prelminary report of an apparently common cause of aortic ejection sounds with potential for serious sequelae, illustrated by two cases.

We report the cases of 2 patients whose tricuspid aortic valves were found to have partial commissural fusion. Both patients experienced complications that were probably related to this abnormality: bacterial endocarditis in 1 instance and a lacunar stroke in the other. In order to illustrate the similarity of physical findings, we also describe the case of a 3rd patient, who had a typical bicuspid aortic valve. Tricuspid aortic valve with partial commissural fusion has been described in autopsy series and has been predicted to cause an ejection sound, but we could find no previously published description of this lesion in living patients. We wish to alert others to the possible presence of aortic commissural fusion, to its potential for serious and likely preventable sequelae, and to the ability of carefully performed transthoracic high-resolution digital echocardiography to demonstrate this condition when its characteristics are found on physical examination.

Aortic Valve↗
PubMed1985

Comparison of a quantitative treadmill exercise score with standard electrocardiographic criteria in screening asymptomatic young men for coronary artery disease.

A computer-derived treadmill exercise score that quantifies the electrocardiographic response to exercise has been reported to have a high sensitivity (87 per cent) and specificity (92 per cent) in patients with a high prevalence of coronary artery disease. To test its accuracy in young, asymptomatic men with a low prevalence of coronary artery disease, we evaluated the responses of 377 military officers (mean age, 36.6 years) by two independent methods. According to standard electrocardiographic criteria, 45 of the subjects (12 per cent) had positive tests, whereas the treadmill exercise score indicated that only 3 (less than 1 per cent) had positive tests. Since two of these three had left ventricular hypertrophy and met only the criteria for the latter without associated coronary artery disease, the treadmill exercise score predicted that only 1 of 377 subjects would have clinically important coronary artery disease. Coronary arteriography, performed in 10 persons with the most positive scores on standard treadmill tests and the highest scores for risk factors, showed that nine subjects did not have coronary artery disease and that one had single-vessel disease (the same subject who the treadmill score predicted would have mild disease). The treadmill exercise score appears to improve the diagnostic specificity of exercise electrocardiography and may be more useful than values on standard stress tests in screening asymptomatic populations for coronary artery disease.

Adult↗
PubMed1979

Coronary vasoactivity of adenosine in the conscious dog.

Intracoronary adenosine infusions in conscious dogs produced half-maximal coronary vasodilation at 0.57 +/- 0.18 (SD) microns and at 1.01 +/- 0.25 microns in open-chest dogs. In both preparations, adenosine at concentrations in the range found in cardiac muscle by direct analysis produced coronary vasodilation equal to that attained during a maximum reactive hyperemic response. The quantitative structure-activity relationship technique was applied to data on the coronary vasoactivity of 68 adenosine analogs to identify the chemical features of this molecule that determine its vasoactivity. These are: (1) the size of the purine base; (2) the inductive effect of C-2 substituent; (3) the electron-withdrawing effect of the C-6 substituent; (4) the glycosylic torsion angle; (5) the ability of the C-2' and C-3' hydroxyls to participate in hydrogen bonding; (7) the absence of sterically hindering groups in the vicinity of C-2' and, more importantly, C-3'; and (8) the inductive effect of the C-5' substituent. The hydrophobicity of these analogs did not correlate with vasoactivity, suggesting that the hydrophilicity of the ribose moiety overshadows any hydrophobic influence of the very weakly aromatic purine base.

Adenine Nucleotides↗
PubMed1977

An implantable semiconductor beta-radiation detector.

An implantable beta-radiation detector suitable for the measurement of reginal blood flow in the experimental animal by the indicator clearance principle is described. A lithium-drifted silicon diode encapsulated in a stainless steel case is sutured over the site of interest. A suitable beta-emitting isotope, such as 85Kr in saline solution, is injected into the arterial supply and its calibrated against a mechanical system and showed excellent agreement up to 600 ml/100 g per min. At very high rates beyond the physiological range, flow was underestimated by a maximum of 10%. In vivo comparisons of myocardial blood flow assessed by the beta detector did not agree well with estimates of flow from a precordial counter or by the microsphere technique. Possible reasons are spatial heterogeneity of regional myocardial blood flow, the greatly different masses of tissue involved, or our inability to achieve sufficient numbers of spheres for accuracy in a 50-mg mass of tissue. The unit was still functional after 50 days in a chronic animal.

Animals↗