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Biomedical subjects

R L Huxley

Publications and source records attributed to R L Huxley.

5 recordsLinked to original sources
PubMed1984

99mTc-pyrophosphate imaging in patients with acute myocardial infarction: comparison of planar imaging with single-photon tomography with and without blood pool overlay.

To test the hypothesis that single-photon emission computed tomography (SPECT) of 99mTc-pyrophosphate (99mTc-PPi) with and without the overlay of tomographic blood pool scintigrams might detect small infarcts not identified by planar imaging, 52 patients were studied 3.2 +/- 2.0(SD) days after hospital admission for suspected acute myocardial infarction. Patients were chosen prospectively for tomographic study primarily, but not exclusively, because planar four-view imaging with 99mTc-PPi was either negative or equivocal. SPECT was performed with a commercial rotating detector system immediately after planar imaging on one occasion. Corresponding 99mTc-PPi and blood pool sections were mapped into opposite halves of a bichromic color table and displayed as an overlay. Planar images, SPECT and SPECT with blood pool overlay were interpreted separately and in random order without knowledge of clinical data. Seventeen patients had transmural infarcts (four anterior, 13 inferior), 19 had nontransmural infarcts, and 16 patients did not have acute myocardial infarction. The sensitivity of SPECT with blood pool overlay was significantly better than planar imaging for the entire group with myocardial infarction (97% vs 78%; p less than .025); this was primarily due to increased sensitivity in the detection of nontransmural myocardial infarction (95% vs 67%; p less than .05), although in one additional patient inferior transmural myocardial infarction was also detected by the SPECT overlay technique. The specificities of the SPECT overlay technique and planar imaging were not significantly different; however, receiver operating characteristic analysis showed enhanced observer confidence with the tomographic method. SPECT without overlay was intermediate in sensitivity and specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Radionuclide ventriculography to evaluate myocardial function.

Developments over the past decade have allowed one to visualize the right and left ventricles using radionuclide techniques and to study the influence of a wide range of physiologic, pharmacologic and surgical interventions on global and regional ventricular function thereby providing important diagnostic insight and improved therapeutic capabilities. These tests are relatively non-invasive, they can be performed serially, they may be performed in patients that are seriously ill, and they have no recognized risk other than low level radiation exposure. With continued improvement in noninvasive imaging and processing and in the sophistication of associated computer systems, one may expect significant and wide ranging additional contributions in the assessment of myocardial function using radionuclide ventriculographic techniques.

Cardiac Output↗
PubMed1983

Left ventricular functional alterations at rest and during submaximal exercise in patients with recent myocardial infarction.

Submaximal exercise testing with radionuclide ventriculography was performed in 117 patients prior to hospital discharge 16.7 +/- 6.7 days (SD) following acute myocardial infarction. The hypothesis tested in this study was that patients with different locations and types of infarction have different functional responses to submaximal exercise prior to discharge. The distribution of the myocardial infarctions were anterior transmural in 33, inferior transmural in 39, anterior nontransmural in 23, inferior nontransmural in 19, and indeterminant in three. Patients with transmural infarction generally had significantly larger resting left ventricular volumes at end-diastole and end-systole and lower ejection fractions and systolic blood pressure/end-systolic volume indexes than patients with nontransmural infarctions (p less than 0.05). During submaximal exercise, the change in end-systolic volume was significantly different in these two groups. When patients were separated further into anterior and inferior transmural subgroups, the patients with anterior transmural infarction had significantly lower left ventricular ejection fractions and higher right ventricular ejection fractions than the group with inferior transmural infarction (p less than 0.05). In response to exercise, the group with anterior transmural infarction had a significant decrease in left ventricular ejection fraction and a blunted systolic blood pressure/left ventricular end-systolic volume index, in comparison to patients with inferior myocardial infarction (p less than 0.05); this was the only group to have a significant increase in end-systolic volume. The group variance for the parameters studied was large, particularly during exercise when the individual responses were frequently directionally opposite from the group means. The group with anterior transmural infarction was the most homogeneous, with 26 of 33 having a directionally abnormal response to submaximal exercise. It was concluded that the group with anterior transmural infarction generally displayed the most abnormal left ventricular function. However, despite significant group differences in resting ventricular function with different infarcts, the intragroup variability at rest and in response to exercise was too great to permit an accurate prediction of the subject's resting ventricular performance or to permit a prediction of exercise response based solely on location of the infarct.

Aged↗