Ratiology and a Complementary Class of Metrics for Cardiovascular Investigations.

Cardiovascular investigations often involve ratio-based metrics or differences: ejection fraction, arterial pressure augmentation index, coronary fractional flow reserve, pulse pressure. Focusing on a single number (ratio or difference) implies that information is lost. The lost companions constitute a well-defined but thus far unrecognized class, having additive value, a physical dimension, and often a physiological meaning.

The Pythagorean theorem reveals the inherent companion of cardiac ejection fraction.

Background: Quantification of ventricular performance requires a comprehensive metric which is manageable for patient care and clinical trials. Ejection fraction (EF) has been embraced as an attractive candidate. However, being a dimensionless ratio, EF has serious limitations.

Sex- and Age-Related Reference Values in Cardiology, with Annotations and Guidelines for Interpretation.

The definition of "abnormal" in clinical sciences is often based on so-called reference values which point to a range that experts by some sort of consensus consider as normal when looking at biological variables. Such a level is commonly calculated by taking (twice) the standard deviation from the mean, or considering certain percentiles. The suspicion or even confirmation of a disease is then established by demonstrating that the value measured exceeds the upper or lower reference value.

Ejection fraction as related to basic components in the left and right ventricular volume domains.

Background: Ejection fraction (EF) is commonly applied as a clinically relevant metric to assess ventricular function. The numerical value of EF depends on the interplay between end-systolic volume (ESV) and end-diastolic volume (EDV). Remarkably, the relative impact of the two constitutive components on EF received little attention.

Monte Carlo method applied to the evaluation of the relationship between ejection fraction and its constituent components.

Ventricular function is routinely assessed by applying the clinically accepted metric ejection fraction (EF). The numerical value of EF depends on the interplay between end-systolic volume (ESV) and end-diastolic volume (EDV). The relative impact of the two constitutive components has received little attention.

Effect of sex, age, and weight on ejection fraction and end-systolic volume reference limits in gated myocardial perfusion SPECT.

Background: The left-ventricular ejection fraction (EF) and end-systolic volume (ESV) are strong predictors of prognosis for cardiac death. Gated myocardial perfusion single-photon emission computed tomography (gSPECT) may be used to measure ESV and EF. However, systematic differences may exist between referred populations.

The effect of imaging time, radiopharmaceutical, full fat milk and water on interfering extra-cardiac activity in myocardial perfusion single photon emission computed tomography.

Background And Aim: Extra-cardiac activity can interfere with observer interpretation of myocardial perfusion single photon emission computed tomography (SPECT) images. Fatty meals and drinks to reduce interference have been tested; however, a simple study of delayed imaging with (99m)Tc-tetrofosmin and (99m)Tc-sestamibi has not been specifically addressed. The aim was to quantify the effects of imaging time, radiopharmaceutical and oral administration of full fat milk and water on interfering activity.