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B Pitt

Publications and source records attributed to B Pitt.

382 records · Page 22Linked to original sources
PubMedDate not supplied

Variations on calculating left-ventricular volume with the radionuclide count-based method.

Various methods for the calculation of left-ventricular volume by the count-based method utilizing red-blood-cell labeling with 99mTc and a parallel-hole collimator are evaluated. Attenuation correction, linked to an additional left posterior oblique view, is utilized for all 26 patients. We examine (1) two methods of calculating depth, (2) the use of a pair of attenuation coefficients, (3) the optimization of attenuation coefficients, and (4) the employment of an automated program for expansion of the region of interest. The standard error of the estimate (SEE) from the correlation of the radionuclide volumes with the contrast-angiography volumes, and the root-mean-square difference between the two volume sets at the minimum SEE are computed. It is found that optimizing a single linear attenuation coefficient assumed for attenuation correction best reduces the value of the SEE. The average of the optimum value from the end-diastolic data and that from the end-systolic data is 0.11 cm-1. This value agrees with the mean minus one standard deviation value determined independently from computed tomography scans (0.13-0.02 cm-1). It is also found that expansion of the region of interest beyond the second-derivative edge with an automated program, in order to correctly include more counts, does not lower the SEE as hoped. This result is in contrast to the results of others with different data and a manual method. Possible causes for the difference are given.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Pulmonary metabolic function can serve as a monitor for lung preservation.

A minimally invasive method for detecting early signs of pulmonary injury through the examination of peripheral blood samples was investigated as a potential method for assaying the effectiveness of lung preservation techniques. A mild, ischemic injury was imposed on lungs in situ by diverting total pulmonary artery blood flow to a pump oxygenator for 1 to 4 hours (average 2 hours) in 16 dogs. Before bypass and at 1/2, 1, and 2 hours following bypass, pulmonary metabolic function was determined by injecting known amounts of the metabolizable vasoactive hormones 14C-5-hydroxytryptamine and 3H-norepinephrine into venous blood and then measuring their single pass concentration-time curves in arterial blood in relation to the concentration of the nonmetabolizable intravascular reference marker indocyanine green (Cardio-Green). The results showed that the ischemic injury produced a significant and reproducible reduction of amine metabolism by the lung. In addition, metabolites of 14C-5-hydroxytryptamine showed a 50% decrease in left atrial blood at the 40% decay point of the intravascular marker, thereby further reflecting the inability of the lung to metabolize 14C-5-hydroxytryptamine in the presence of endothelial injury. The method is a sensitive assay for lung injury that can be performed in serial fashion in the closed-chest experimental animal or patient. The procedure may have potential evaluating techniques of lung preservation or for detecting early signs of rejection in the transplanted lung before histologic or radiographic changes become apparent.

Animals↗