Search results
Results From The WOW.Com Content Network
The area enclosed by the PV loop is a measure of the ventricular stroke work, which is a product of the stroke volume and the mean aortic or pulmonary artery pressure (afterload), depending on whether one is considering the left or the right ventricle.
Left ventricular PV loops are considered to be the gold standard for hemodynamic assessment and are widely used in research to evaluate cardiac performance. While it has long been possible to measure pressure in real time from the left ventricle, measuring the volume was technically more difficult.
Afterload is largely dependent upon aortic pressure. Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. [1] As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively.
A pressure–volume diagram (or PV diagram, or volume–pressure loop) [1] is used to describe corresponding changes in volume and pressure in a system. They are commonly used in thermodynamics , cardiovascular physiology , and respiratory physiology .
Aortic regurgitation causes both volume overload (elevated preload) and pressure overload (elevated afterload) of the heart. [14] The volume overload, due to elevated pulse pressure and the systemic effects of neuroendocrine hormones causes left ventricular hypertrophy (LVH). [9] There is both concentric hypertrophy and eccentric hypertrophy in AI.
By contrast, the Anrep effect occurs at constant preload, triggered solely by afterload. [1] [2] [3] It is characterized by increased contractility (steeper end-systolic pressure-volume relationship) and higher stroke work, without changes in stroke volume or end-diastolic volume. [3] [4]
Pressure overload of the right ventricle leads to right ventricular hypertrophy; right image. Pressure overload refers to the pathological state of cardiac muscle in which it has to contract while experiencing an excessive afterload .
Arterial compliance is an important cardiovascular risk factor. Compliance diminishes with age and menopause. Arterial compliance is measured by ultrasound as a pressure (carotid artery) and volume (outflow into aorta) relationship. [5] Compliance, in simple terms, is the degree to which a container experiences pressure or force without disruption.