afterload
1. The arrangement of a muscle so that, in shortening, it lifts a weight from an adjustable support or otherwise does work against a constant opposing force to which it is not exposed at rest. 2. The load or force thus encountered in shortening.
- ventricular a. formerly and erroneously, the arterial pressure or some other measure of the force that a ventricle must overcome while it contracts during ejection, contributed to by aortic or pulmonic artery impedance, peripheral vascular resistance, and mass and viscosity of blood; now, more rigorously expressed in terms of the wall stress, i.e., the tension per unit cross-sectional area in the ventricular muscle fibers (calculated by an expansion of Laplace law using pressure, internal radius, and wall thickness) that is required to produce the intracavitary pressure required during ejection.

* * *

af·ter·load 'af-tər-.lōd n the force against which a ventricle contracts that is contributed to by the vascular resistance esp. of the arteries and by the physical characteristics (as mass and viscosity) of the blood

* * *

af·ter·load (afґtər-lōd″) in cardiac physiology, the force against which cardiac muscle shortens. In isolated muscle it is the force resisting shortening after the muscle is stimulated to contract; in the intact heart it is the pressure against which the ventricle ejects blood, as measured by the stress acting on the ventricular wall following the onset of contraction, determined largely by the peripheral vascular resistance and by the physical characteristics of and blood volume in the arterial system. It is often estimated by determining systolic arterial pressure, from which can be determined the systolic wall stress; see also Laplace's law, under law.

Medical dictionary. 2011.

Look at other dictionaries:

  • Afterload — In cardiac physiology, afterload is used to mean the tension produced by a chamber of the heart in order to contract. If the chamber is not mentioned, it is usually assumed to be the left ventricle. However, the strict definition of the term… …   Wikipedia

  • Afterload — Als Nachlast (engl. afterload) wird eine den Herzmuskel beeinflussende Kraft bezeichnet, welche dem Blutauswurf aus den Herzkammern (Ventrikel) in das Blutgefäßsystem des Körpers hinein entgegenwirkt. Sie kann am besten als Gesamtwiderstand der… …   Deutsch Wikipedia

  • afterload — noun The load on a working muscle from a constant opposing force …   Wiktionary

  • Afterload — After|load [á̱fterlo̱ud; Neubildung aus engl. after = nach u. engl. load = Last, Druck] s; s, s: „Nachlast“, Belastung, gegen die sich ein Muskel verkürzt (für das Herz der Aorten bzw. Pulmonaldruck) …   Das Wörterbuch medizinischer Fachausdrücke

  • afterload — n. (In Cardiac Physiology) tension caused by the heart muscle after contraction …   English contemporary dictionary

  • afterload — …   Useful english dictionary

  • Stroke volume — (SV) is the volume of blood pumped by the right/left ventricle of the heart in one contraction. Specifically, it is the volume of blood ejected from ventricles during systole.The stroke volume is not all of the blood contained in the left… …   Wikipedia

  • Contractility — Myocardial contractility is the intrinsic ability of the heart to contract independent of preload and afterload. Changes in the ability to produce force during contraction result from different degrees of binding between myosin (thick) and actin… …   Wikipedia

  • Enhanced external counterpulsation — External counterpulsation (ECP) is a procedure performed on individuals with ischemic cardiomyopathy in order to diminish the symptoms of their ischemia. In various studies, ECP has been shown to relieve angina1,2, improve exercise tolerance³,… …   Wikipedia

  • Aortic insufficiency — See also: mitral regurgitation and tricuspid insufficiency Aortic insufficiency Classification and external resources Micrograph of myxomatous degeneration – a cause of aortic insufficiency …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”