Biomedical subjects

P F Moynihan

Publications and source records attributed to P F Moynihan.

8 recordsLinked to original sources

PubMed1982

Enhanced detection of the evolution of tissue changes after acute myocardial infarction using color-encoded two-dimensional echocardiography.

Acute myocardial infarction was produced in 26 dogs by ligation of the left anterior descending coronary artery. Two-dimensional echocardiograms (2-D echoes) were performed through the chest wall before and serially after coronary ligation. The dogs were then killed in four groups at the following intervals: 24-48 hours, 1-2 weeks, 3 weeks and 6-8 weeks. Each 2-D echo was processed through a video quantizer, which encoded echo amplitudes progressively into eight regions of color. The myocardium was graded with respect to color composition in regions that showed any abnormally contracting segment (ACS). The ACS exhibited a progressive increase in echo intensity that became maximal 6-8 weeks after coronary ligation. Histopathologic and histochemical studies verified that these increases in echo amplitude correlated with the evolution of healing and myocardial scar formation. At 6-8 weeks, the mean collagen content of infarcted myocardium had increased by a factor of 4; concurrently, ACS echo amplitude had increased two- to threefold. These observations suggest that color-encoded 2-D echo promotes facile perception of serial changes in tissue characteristics that result from acute myocardial infarction.

Animals↗

PubMed1981

Quantitative detection of regional left ventricular contraction abnormalities by two-dimensional echocardiography. I. Analysis of methods.

Different approaches to the quantification of regional left ventricular (LV) function from two-dimensional echocardiographic (2-D echo) images were assessed for their ability to optimize interobserver reproducibility in a heterogeneous patient population and to minimize the variability of regional function observed in a homogeneous normal population. Areas, hemiaxis and perimeter measurements were examined, as were the effect of the degree of image subdivision into halves, quadrants or octants. Each approach was also tested using both a fixed and a floating frame of reference for the definition of a regional-axis system. The area method was consistently superior to either linear method in optimizing both reproducibility and variability. Reproducibility decreased inversely with the degree of subdivision. The axis-system frame of reference had no effect on reproducibility. The floating-axis system yielded the same variability as the fixed system for short-axis sections at the mitral valve level, but slightly less variability for a papillary muscle level section. We conclude that area-based methods are superior for the evaluation of regional LV function with 2-D echo, but the degree of subdivision of the image and the frame of reference chosen do not greatly affect reproducibility or variability and should be chosen based on their performance in a well-defined clinical population.

Diastole↗

PubMed1981

Quantitative detection of regional left ventricular contraction abnormalities by two-dimensional echocardiography. II. Accuracy in coronary artery disease.

The quantitative approaches to the assessment of regional left ventricular (LV) function described in the preceding paper were applied in a well-defined population of patients with coronary artery disease. Two groups were chosen by electrocardiographic and angiographic criteria: group 1 had infarction and regional wall motion abnormalities and group 2 had no infarction and normal wall motion. Sensitivity to detect wall motion defects, specificity to correctly categorize normal segments, and overall predictive accuracy were evaluated for each two-dimensional echocardiographic approach. In addition, the ability of each method to localize regional contraction defects properly was evaluated. Area methods yielded better predictive accuracy than linear methods (87-95% vs 76-84%). No significant differences in accuracy were noted between quadrant and octant approaches. The fixed external-axis system was superior to a floating one for localizing contraction defects. We conclude that an area-based method, using a fixed-axis system and either octant or quadrant image subdivision, provides the best combination of predictive accuracy in categorizing LV segments as normal or abnormal and the greatest ability to localize LV regional abnormalities.

Adult↗

PubMed1980

Echocardiography in acute and remote myocardial infarction.

Two dimensional echocardiography is just beginning to be used to characterize cardiac damage in patients with acute myocardial infarction. The two dimensional approach allows for a more comprehensive evaluation of cardiac anatomy and is able to detect with high sensitivity changes in regional wall motion that previously were sometimes missed or only found with difficulty using M mode echocardiography. Two dimensional echocardiography appears to offer a basis for quantifying the extent of myocardial damage in acute myocardial infarction and thus may permit objective assessment of therapeutic modalities and prognosis. In addition, the technique facilitates recognition of specific complications in acute myocardial infarction. In particular, the technique offers te ability to distinguish true from false ventricular aneurysm, postinfarction ventricular septal defect from papillary muscle dysfunction and rupture, and right ventricular infarction from cardiac tamponade.

Animals↗

PubMed1980

Echocardiographic evaluation of left ventricular function.

The ability of echocardiography to assess left ventricular function is entering an era of transition. Most existing data have been derived from M-mode measurements made along a single echo beam axis and, as such, were based on the assumption that the performance of the sampled segment represented that of the whole ventricle. The recent availability of two dimenensional echocardiography lessens the need to rely on this assumption.

Echocardiography↗

PubMed1979

Approaches to determination of left ventricular volume and ejection fraction by real-time two-dimensional echocardiography.

Left ventricular volumes and ejection fraction were derived from real time two-dimensional echocardiographic images (2 DE) and single plane (RAO) left ventricular cineangiograms in a series of 50 patients. Prospective application of a series of 6 alternate algorithms showed that a modified Simpson's rule approach using mitral and papillary muscle cross sections and an apical four chamber view provided the best 2 DE - angiographic correlations: for end-diastolic volume r = 0.82, SEE = 39 ml; for end-systolic volume r = 0.90, SEE = 29 ml and for ejection fraction r = 0.80, SEE = 0.09. The large SEE for volume determination indicates that further refinements are necessary to predict left ventricular volumes adequately; however, ejection fraction can be derived with an accuracy which allows practical clinical decisions in patients with satisfactory 2 DE images.

Cardiac Output↗

PubMed1979

Assessment of left ventricular ejection fraction and volumes by real-time, two-dimensional echocardiography. A comparison of cineangiographic and radionuclide techniques.

Five different algorithms for determining left ventricular (LV) ejection fraction (EF) and volumes from two-dimensional echocardiographic examination (TDE) were compared with standard methods for obtaining EF and volume from x-ray cineangiography (cine) and EF from radionuclide ventriculography (RVG) in 35 patients. Although all methods correlated positively, the degree of correlation varied with the algorithm used. For EF determination, TDE algorithms (especially those using multiple planes of section) were superior to unidimensional algorithms commonly used with M-mode echocardiography. The best algorithm (modified Simpson's rule) correlated well enough with cine EF (r = 0.78; SEE 0.097) and RVG EF (r = 0.75; SEE 0.087) to make clinically useful estimates. TDE volumes also correlated meaningfully with cine end-diastolic and end-systole volumes (r = 084; n = 70) but were associated with a large standard error of the estimate (43 ml) and offered less advantage over unidimensional volume estimates. Quantitative application of TDE appears to be a useful noninvasive method of evaluating LVEF, but is not as useful for estimating LV volumes.

Cineangiography↗

PubMedDate not supplied

A system for quantitative evaluation of left ventricular function with two-dimensional ultrasonography.

Phased-array ultrasonic imaging systems produce real-time sectional images of the left ventricle. To quantify left ventricular function, a light-pen-based system was developed using a minicomputer to analyze the geometry of ultrasound images and measure left ventricular volume, ejection fraction, and regional contraction. System accuracy was evaluated by comparing measurements abtained from left ventricular cineangiograms at cardiac catheterization on a series of 25 patients to echocardiographic left ventricular long- and short-axis linear dimensions (r = 0.92, S.E.E. = 0.67 cm), end-diastolic volume (r = 0.84, S.E.E. = 45 cm3), and ejection fraction (r = 0.80, S.E.E. = 0.10). Five patients from the study population with electrocardiographically documented transmural myocardial infarcts had regional contraction abnormalities detected by this analytic approach. Quantitative application of two-dimensional echocardiography appears to be a useful noninvasive method of evaluating left ventricular ejection fraction and has potential to define regional contraction abnormalities objectively.

Cardiac Output↗