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Biomedical subjects

S B Simon

Publications and source records attributed to S B Simon.

10 recordsLinked to original sources
PubMed1990

Automated quantitation of indexes of coronary lesion complexity. Comparison between patients with stable and unstable angina.

Analysis of lesion morphology is becoming increasingly important in the study of coronary artery disease. Lesion irregularity has been shown to be one of the most important predictive features for development of myocardial infarction. Most studies to date have used only qualitative assessments of morphology and are thus subject to variability and lack of standardization inherent in subjective visual inspection. We describe a new approach that allows quantitation of lesion morphology. Fifty-nine patients with unstable angina and 17 patients with stable angina were compared. Five morphometric parameters were tested (peaks per centimeter, summed maximum error per centimeter, integrated error per centimeter, number of major features per centimeter, and scaled edge length ratio), four of which were significantly different between the two groups and indicated greater lesion complexity in unstable compared with stable angina patients. No correlation was found between the parameters tested and the degree of luminal narrowing, showing the method's independence from traditional assessments of lesion severity. Excellent intraobserver and interobserver reproducibility was found for all of the parameters. This technique provides a more rigorous approach for analysis of lesion morphology than has previously been available, may provide a method for premorbid detection of high-risk lesions amenable to interventional therapy, and is especially well suited to detect subtle changes in lesion morphology after therapeutic interventions because the parameters are derived on a continuous scale and are not categorical.

Aged↗
PubMed1988

A comparison of 35 mm cine film and digital radiographic image recording: implications for quantitative coronary arteriography. Film vs. digital coronary quantification.

To assess potential differences in the intrinsic properties of image recording media and their impact on quantitative coronary arteriography, we used an automatic quantitative arteriography computer program to analyze cine film and digital radiographic images of a radiographic arterial phantom. The phantom consisted of a lucite plate with precision-drilled lumena ranging from 0.5 to 5.0 mm in diameter. Film images were digitized at 2048 X 2048 pixel resolution, and digital radiographic images were acquired at 512 X 512 and 1024 X 1024 resolution. Arterial geometric diameter, percent diameter stenosis, densitometric relative cross-sectional area, and densitometric percent area stenosis were measured. All three techniques were equivalent in measuring diameters with a high degree of overall accuracy (R greater than .992). All methods overestimated diameters below 1.0 mm. Both 512 X 512 and 1024 X 1024 digital images were superior to film for densitometric measurement of relative area (R = .995 vs. R = .940, P = .0032). We conclude that automated analysis of digital radiographic images yields results that are similar in geometric precision but greater in densitometric precision than film analysis.

Cineradiography↗
PubMed1987

Quantitative regional curvature analysis: an application of shape determination for the assessment of segmental left ventricular function in man.

All traditional techniques of regional ventricular function analysis depend upon one or more assumptions about coordinate, reference, or indexing systems, idealized ventricular geometry, and the uniformity of ventricular contraction. Therefore, a method of shape analysis was developed that allows the quantitation of regional curvature and is independent of the assumptions outlined. This was implemented on a commercial image processing unit and applied to silhouettes of 30-degree right anterior oblique left ventriculograms. Three groups with abnormal wall motion (anterior abnormality, n = 23; inferior abnormality, n = 23; anterior and inferior abnormalities, n = 22) were analyzed and compared to a group with normal regional function (n = 22). Relatively few significant quantitative curvature differences were noted at end diastole among the groups. These few abnormalities described a slight increase in curvature or globularity of the anterior and inferior walls. More marked and extensive aberrations were detected at end systole. The group with anterior wall motion disturbances showed four distinct areas of curvature abnormality. Excessive curvature was present on either side of the apex (anterior and inferoapical regions) and apical curvature was less than normal. The fourth region was in the inferior zone, which showed curvature values that were less than normal, suggesting increased inward motion contralateral to the anterior abnormality. The group with inferior wall motion abnormalities also showed excessive end-systolic curvature on either side of the apex (diaphragmatic and anteroapical zones) and deficient curvature at the apex. A combination of these regional morphologic abnormalities was noted in the group with both anterior and inferior dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed1987

Automated quantitative coronary arteriography: morphologic and physiologic validation in vivo of a rapid digital angiographic method.

Quantitative coronary arteriography has been shown to be useful in assessing the extent of coronary disease, its functional significance, and its response to therapeutic interventions. Most current methods rely either on hand-drawn arterial contours or automatic edge-detection algorithms applied to 35 mm cineangiograms. To assess the performance in vivo of a new, fully automatic, rapid coronary quantitation program, dogs were instrumented with precision-drilled, plastic cylinders to create intraluminal stenoses in the left anterior descending and/or circumflex arteries, as well as with high-fidelity micromanometers and electromagnetic flow probes. Stenosis diameters ranged from 0.83 to 1.83 mm. Biplane, on-line, digital coronary angiograms and cineangiograms were recorded during standard selective coronary arteriography in the closed-chest preparation. The on-line digital images were analyzed in nonsubtracted and subtracted modes. Cineangiograms were digitized to allow coronary quantitation by the same computer program. There was an excellent correlation between known and measured minimal diameter stenoses (r = .87 to .98, SEE = 0.09 to 0.24 mm). Interobserver and intraobserver variability analysis showed high reproducibility (r = .90 to .97, SEE = 0.12 to 0.23 mm). The best results in both analyses were achieved by nonsubtracted digital imaging and the worst by cineradiography. Measures of percent diameter stenosis, percent area stenosis (geometric and videometric), and absolute minimal cross-sectional area (geometric and videometric) were all significantly correlated with independent measures of actual coronary flow reserve. This study provides direct anatomic and physiologic validation in vivo of a new and rapid coronary quantitation method suitable for analysis of both digital angiograms and cineangiograms.

Angiography↗
PubMed1985

Validation in dogs of a rapid digital angiographic technique to measure relative coronary blood flow during routine cardiac catheterization.

Assessment of the functional significance of anatomically defined coronary stenoses has been hampered by the lack of clinically applicable techniques of measuring coronary blood flow or flow ratios. A digital angiographic technique is reported that allows rapid analysis of relative regional coronary blood flow during routine cardiac catheterization. This technique was validated in dogs by comparing digital flow ratio estimates with electromagnetic-flow (EMF) ratio measurements. Fourteen open-chest dogs had EMF probes placed on the proximal left anterior descending artery before selective coronary angiography. Electrocardiographically gated images were acquired directly by a digital radiographic system during both baseline blood flow and either contrast or papaverine-induced hyperemia. Dual-parameter functional images were generated using color and intensity coding to represent contrast arrival time and contrast density, respectively. For analysis, myocardial areas of interest were created over the distal perfusion bed of the left anterior descending coronary artery. Mean contrast density/appearance time (CD/AT) values were computer calculated as the mean density divided by the mean arrival time for each. Coronary flow reserve was determined as the ratio of the CD/AT value for a hyperemic image divided by the CD/AT value for the corresponding baseline image. CD/AT ratios correlated well (r = 0.92) with actual EMF ratios (CD/AT Ratio = 0.90 EMF Ratio +0.12, n = 48 ratios). Reproducibility was +/- 13%. Interobserver (r = 0.99) and intraobserver (r = 0.98) variability was excellent. Thus, rapid, accurate and reproducible estimates of relative regional coronary blood flow are possible using digital radiography.

Animals↗
PubMed1979

Multiple, prolonged actions of neuroendocrine bag cells on neurons in Aplysia. I. Effects on bursting pacemaker neurons.

1. The bag cells are a group of neuroendocrine cells located in the abdominal ganglion of Aplysia. Accumulated evidence suggests they synthesize and release egg-laying hormone (ELH), a peptide that induces egg laying. In this and the following paper (37) we describe five types of prolonged neural responses in cells of the isolated abdominal ganglion that are produced by stimulated bag cell activity. 2. Prolonged, 5- to 40-min bursts of spike activity were triggered in the normally silent bag cells by local stimulation of one of the bag cell clusters with brief, 0.6- to 2-strains of pulses. This local stimulation minimized the possible effects of the stimulus on other ganglion cells and initiated bag cell activity similar to what has been recorded in intact animals at the initiation of egg laying. 3. Following onset of triggered bag cell activity there is an increase in the amplitude of the bursting pacemaker potential in cell R15 that results in augmented bursting activity in this autoactive cell for up to 3 h. The increase begins in less than 1 min and reaches a maximim after 8--20 min. In two other bursting pacemaker cells, L3 and L6, there is a second type of response, slow inhibition, consisting of a smoothly graded hyperpolarization that begins in 5--14 s, reaches a peak value of 10--20 mV after 30 s, and results in a decrease in the spontaneous spike activity of these cells for 3 h or longer. Both types of responses are contingent on the occurrence of bag cell activity, they depend on prolonged bag cell activity for their normal expression, and they occur in the absence of the fast interactions characteristic of conventional synapses. 4. The results reveal at the level of intracellular recordings prolonged actions of peptide-secreting neuroendocrine cells on the central nervous system. The role of ELH as a putative mediator of one or more of these actions is discussed.

Animals↗