Performance of a fully automated program for measurement of left ventricular ejection fraction

Amino Acids in Swine Nutrition and Production

Amino acids are the building blocks of proteins in animals, including swine. With the development of new analytical methods and biochemical research, there is a growing interest in fundamental and applied studies to reexamine the roles and usage of amino acids (AAs) in swine production. In animal nutrition, AAs have been traditionally classified as nutritionally essential (EAAs) or nutritionally nonessential (NEAAs). AAs that are not synthesized de novo must be provided in diets. However, NEAAs synthesized by cells of animals are more abundant than EAAs in the body, but are not synthesized de novo in sufficient amounts for the maximal productivity or optimal health (including resistance to infectious diseases) of swine. This underscores the conceptual limitations of NEAAs in swine protein nutrition. Notably, the National Research Council (NRC 2012) has recognized both arginine and glutamine as conditionally essential AAs for pigs to improve their growth, development, reproduction, and lactation. Results of recent work have also provided compelling evidence for the nutritional essentiality of glutamate, glycine, and proline for young pigs. The inclusion of so-called NEAAs in diets can help balance AAs in diets, reduce the dietary levels of EAAs, and protect the small intestine from oxidative stress, while enhancing the growth performance, feed efficiency, and health of pigs. Thus, both EAAs and NEAAs are needed in diets to meet the requirements of pigs. This notion represents a new paradigm shift in our understanding of swine protein nutrition and is transforming pork production worldwide.

Comparison of post-stress ejection fraction and relative left ventricular volumes by automatic analysis of gated myocardial perfusion single-photon emission computed tomography acquired in the supine and prone positions

BACKGROUND

We have previously described an automatic method for measuring left ventricular ejection fraction (LVEF) for myocardial perfusion single-photon emission computed tomography (SPECT). The repeatability of this method has not been previously described.

METHODS AND RESULTS

This study compares LVEF and relative end-systolic and end-diastolic volumes assessed from myocardial perfusion SPECT by our automatic method in 180 consecutive patients undergoing gated myocardial perfusion SPECT with injection of 99mTc-labeled sestamibi in whom the acquisitions were performed sequentially in supine and prone positions. The algorithm operated completely automatically in the prone and supine positions in 178 of the 180 patients. Very high correlations were observed for LVEF (r = 0.93), relative left ventricular end-systolic volume (r = 0.98), and relative left ventricular end-diastolic volume (r = 0.97). The mean paired absolute difference between LVEFs in the prone and supine position was 3.8+/-3.2, for left ventricular end-systolic volume was 4.9+/-4.8 ml, and for left ventricular end-diastolic volume was 7.4+/-6.7 ml. When patients were classified by the extent and severity of stress perfusion defect, there was no significant difference in repeatability for the measurements in any category.

CONCLUSIONS

Our algorithm for automatic quantification of LVEF and relative end-systolic and end-diastolic volumes from gated 99mTc sestamibi myocardial perfusion SPECT is repeatable. When performed in the prone position, values of ejection fractions and ventricular volumes are essentially identical to those obtained in the supine position.

Quantitative radionuclide angiocardiography

Quantitation of cardiac pump function using radionuclide angiocardiography provides objective information for the management of patients with heart disease. Left and right ventricular ejection fraction, stroke volume ratio, ejection rate, diastolic function, ventricular volume, parametric imaging, amplitude and phase analysis, and shunt quantification can be measured from the radionuclide angiocardiogram at rest, during exercise, and during pharmacologic interventions. This review describes these methods and discusses their reliability and their role in the clinical assessment of patients with cardiac disease.

Linear discriminant analysis of regional ejection fractions in the diagnosis of coronary artery disease

We studied the application of linear discriminant analysis to the computer assisted interpretation of rest and exercise gated blood pool studies. Data were obtained in 45 patients in whom the presence or absence of coronary artery disease was determined by coronary angiography. Automated analysis of regional ejection fractions using a linear discriminant function (LDF) was compared to the fully automated calculation of global ejection fraction and to the subjective evaluation of wall motion. A LDF constructed from the data for the first 31 consecutive patients correctly classified 25/31 (81%). The change in global ejection fraction correctly classified 24/31 (77%) and wall motion analysis 25/31 (81%). In a distinct group of 14 patients the same LDF correctly classified 12/14 (86%), global ejection fraction 9/14 (64%) and wall motion analysis 10/14 (71%).

Mechanism of decreased left ventricular stroke volume during inspiration in man

Radionuclide ventriculography was performed in 15 healthy subjects during quiet breathing and during inspiration against a 24 cm H2O threshold load with a respiratory gating technique. Inspiratory threshold loading caused an inspiratory decrease in ejection fraction from 64% to 59% (p less than .001). Stroke counts proportional to stroke volume decreased by 9.6% (p less than .02) due to an increase in end-systolic counts of 15.9% (p less than .05). End-diastolic counts decreased in four subjects and increased in three subjects, but the mean counts did not change significantly. These findings suggest that negative pleural pressure causes an impediment to left ventricular ejection comparable to an increase in arterial pressure. Respiratory gating of radionuclide ventriculography during loaded breathing is suggested as a controlled stress on the ventricle for diagnostic purposes.