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In clinical cardiology the term "diastolic function" is most commonly referred as how the heart fills. [1] Parallel to "diastolic function", the term " systolic function" is usually referenced in terms of the left ventricular ejection fraction (LVEF), which is the ratio of stroke volume and end-diastolic volume . [ 2 ]
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Effects of impaired diastolic function [ edit ] Brain natriuretic peptide (BNP) is a cardiac neurohormone secreted from ventricular myocytes (ventricular muscle cells) at the end of diastole—this in response to the normal, or sub-normal (as the case may be), stretching of cardiomyocytes (heart muscle cells) during systole.
During ventricular diastolic filling, the elevated atrial pressure is transmitted to the LV during filling so that LV end-diastolic volume (and pressure) increases. This would cause the afterload to increase if it were not for the reduced outflow resistance (due to mitral regurgitation) that tends to decrease afterload during ejection.
Diastolic dysfunction is associated with a reduced compliance, or increased stiffness, of the ventricle wall. This reduced compliance results in an inadequate filling of the ventricle and a decrease in the end-diastolic volume. The decreased end-diastolic volume then leads to a reduction in stroke volume because of the Frank-Starling mechanism. [1]
Heart rate and rhythm - loss of a normal atrial rhythm (e.g., atrial fibrillation causes loss of the A wave). The height of the E wave becomes dependent on the length of the cardiac cycle (variable) rather than a measure of diastolic function. Similarly, pacing and tachycardia result in alterations, whereas bradycardia increases the E/A ratio.
Immediately following the arterioles are the capillaries. Following the logic observed in the arterioles, we expect the blood pressure to be lower in the capillaries compared to the arterioles. Since pressure is a function of force per unit area, (P = F/A), the larger the surface area, the lesser the pressure when an external force acts on it ...
A Wiggers diagram modified from [1]. A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century.