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Biomedical subjects

J R Corbett

Publications and source records attributed to J R Corbett.

At least 91 records · Page 5Linked to original sources
PubMed1982

Radionuclide techniques for valvular regurgitant index: comparison in patients with normal and depressed ventricular function.

We compared contrast angiography with three techniques of quantitating valvular regurgitation from radionuclide ventriculograms in 70 patients: 45 with documented regurgitation graded 1-4+, and 25 without regurgitation. The radionuclide "regurgitant index" (ratio of L to R ventricular stroke counts) was measured from fixed end-diastolic regions of interest (method A), from separate end-diastolic and end-systolic regions of interest (method B), and from a "stroke-volume image" (method C). Sensitivities for detecting 1+ or more regurgitation were: method A = 57.8%, method B = 37.8% and method C = 62.2%. Sensitivities for detecting 2+ or more regurgitation were: method A = 74.2%, method B = 54.8%, and method C = 77.4%. All methods are greater than 97% specific. Interobserver coefficients of variability were: method A = 9.1%, method B = 19.2%, and method C = 5.4%. The sensitivity of each method was improved when left-ventricular ejection fractions were greater than 0.35. No method consistently differentiated between 2+, 3+, and 4+ valvular regurgitation.

Angiography↗
PubMed1981

Double-blind, randomized, placebo-controlled comparison of propranolol and verapamil in the treatment of patients with stable angina pectoris.

This study was performed to compare the relative efficacies of propranolol and verapamil in patients with stable angina pectoris. In 18 patients (16 men, two women, mean age 58 years) with coronary artery disease and angina of effort, the results of low (40 mg every 6 hours) and high-dose (80 mg every 6 hours) propranolol therapy were compared to those of low (80 mg every 6 hours) and high-dose (120 mg every 6 hours) verapamil therapy in a double-blind, randomized, placebo-controlled evaluation which lasted eight weeks: two weeks of placebo therapy, two weeks of propranolol or verapamil (one week low-dose, one week high-dose) therapy, three days of down-titration followed by one week of placebo therapy, two weeks of propranolol or verapamil therapy (whichever was not given earlier in the trial) (one week low-dose, one week hgh-dose) and three days of down-titration. During each period the following were quantitated: (1) chest pains/week; (2) nitroglycerin used/week; (3) transient ischemic S-T segment deviations and highest grade of ventricular ectopic activity on two-channel Holter monitor; (4) S-T segment deviations during supine bicycle exercise; (5) left ventricular volumes and ejection fraction at rest and during exercise (assessed by equilibrium gated blood pool scintigraphy); and (6) pulmonary function studies. Propranolol and high-dose verapamil therapy significantly reduced the frequency of angina, and high-dose verapamil therapy diminished both the need for nitroglycerin and the frequency of transient ischemic S-T segment deviations on Holter monitor. Neither agent exerted a clinically-important deleterious influence on left ventricular volumes or the ejection fraction. Forced vital capacity and forced expiratory volume were worsened by propranolol but not by verapamil. Thus, in the patient with angina of effort, verapamil is a satisfactory therapeutic alternative to propranolol.

Adult↗
PubMed1981

The prognostic value of submaximal exercise testing with radionuclide ventriculography before hospital discharge in patients with recent myocardial infarction.

To test the hypothesis that patients at risk of future cardiac events can be identified by sub-maximal exercise testing with radionuclide ventriculography (RVG), 61 patients were studied a mean of 19 +/- 1.0 days (+/- SEM) after acute myocardial infarction (MI). RVGs were used to measure left ventricular ejection fraction (LVEF), wall motion score (WMS), end-diastolic volume (EDV) and end-systolic volume (ESV), and the ratio of systolic blood pressure to ESV (P/V index) at rest and during submaximal exercise. Frank lead ECGs were analyzed for ST-segment change and arrhythmias. These patients were followed for a mean of 9.6 months (60 for 6 months or more and one for 3 months) to determine the incidence of cardiac death, recurrent MI, unstable or medically refractory angina, persistent congestive heart failure (CHF) or limiting angina; these problems were considered to be important cardiac events. At the 6-month follow-up, 37 patients had important complications: four patients died, five had MI, seven had unstable or medically refractory angina, 11 had persistent CHF and 10 had severe limiting angina. The sensitivity and specificity of RVG in predicting the important postinfarct complications listed above were 95% and 96% for failure to increase LVEF by at least 5 units, 95% and 96% for an increase in ESV of more than 5%, 97% and 88% for failure of the P/V index to increase by more than 35%, and 81% and 88%, respectively, for a decrease in WMS. The sensitivity and specificity of the ECG in predicting important complications were 54% and 58%, respectively. The rest and submaximal exercise RVG variables, the ECG, a history of MI, the location of the infarction, Killip class III, age, sex, and maximal work load performed were analyzed statistically to determine the best predictors of prognosis. The change with exercise in LVEF, ESV and the P/V index were most significant variables in predicting prognosis during the 6-month follow-up period. When patients with subsequent cardiac events were separated into those with death, recurrent MI and unstable or medically refractory angina as major cardiac events, and patients with persistent CHF and limiting angina as less important ("minor") cardiac events, only the peak submaximal exercise LVEF and history of MI were significant in distinguishing these groups. In patients without important cardiac events during the 3- and 6-month follow-up, 70% and 88%, respectively, no abnormality in the responses of LVEF, ESV, or P/V index to submaximal exercise. These results suggest that submaximal exercise testing with RVG is a highly sensitive means of classifying patients at the time of hospital discharge after MI according to the likelihood of having cardiac events during the ensuing 6 months.

Adult↗
PubMed1981

Simultaneous display of gated technetium-99m stannous pyrophosphate and gated blood-pool scintigrams.

We have developed a method by which any two sets of R-wave-synchronized radionuclide images may be registered, color-coded, and displayed in cinematic fashion so that the image sets are superimposed and shown simultaneously in contrasting colors. The technique has been applied to technetium-99m stannous pyrophosphate (Tc-99m PPi) and equilibrium blood-pool images. Gated Tc-99m PPi and gated blood-pool image sets (16 frames per cardiac cycle) were acquired in identical projections. Image sets were then registered, if necessary, and color-coded by a computer algorithm. Our initial experience suggests that this overlay technique may be of value to: (a) detect right ventricular infarction with greater precision; (b) provide a better estimate of anatomic location and circumferential extent of Tc-99m PPi myocardial uptake relative to the ventricular blood pool; and (c) distinguish between segmental contraction abnormalities caused by recent infarction (identified by abnormal Tc-99m PPi uptake) and segmental contraction abnormalities caused by ischemia or previous myocardial infarction.

Adult↗
PubMed1977

Industrial dermatitis in Northern Ireland.

Industrial injuries and disablement benefits paid for industrial dermatitis (PD 42) in Northern Ireland are analyzed by age, industry and substance responsible. The most significant trend is a decrease in the number of cases due to cement and an increase in the number of nickel cases.

Dermatitis, Contact↗
PubMed1967

Intracellular Distribution of p-Nitrophenyl-Phosphatase in Plants.

Less than 10% of the acid p-nitrophenylphosphatase activity of plant extracts was sedimentable under a variety of conditions including zonal centrifugation. The sedimentable fraction did not show the latency properties characteristic of animal lysosomes. We conclude that, at least operationally, plant acid phosphatase is a soluble enzyme and that it is not suitable as a lysosomal marker. The plant tissues employed were pea cotyledons, cauliflower florets, turnip storage organs, onion embryos, and leaves of red oak and soybean.

Journal Article↗
PubMedDate not supplied

Clinical review of attenuation-corrected cardiac SPECT.

Rather than the introduction of a heralded technologic advancement in cardiac SPECT imaging challenging the accuracy of PET perfusion imaging, the commercial introduction of attenuation correction has been met with at least as many negative as positive reports. Some studies have reported significant improvements in specificity or specificity and sensitivity, especially for high-risk patterns of coronary artery disease; others have reported no improvement or a decrease in accuracy resulting from the introduction of troublesome artifacts. Although this review has attempted to emphasize the positive aspects of attenuation-corrected cardiac SPECT perfusion imaging and the potential for improved patient care it may provide, several negative reports continue to appear. Still there has been sufficient positive data reported to suggest that with fully developed, accurate, and robust correction methods, significant gains in SPECT assessments of the presence and extent of CHD, patient risk, and myocardial viability can be anticipated. Ultimately attenuation correction for cardiac SPECT should have a positive impact on the management of patients with coronary artery disease with important savings in lives and health care dollars.

Coronary Disease↗