<P> Afterload is the stress in the wall of the left ventricle during ejection . In other words , it is the end load against which the heart contracts to eject blood . Afterload is readily broken into components : one factor is the aortic pressure the left ventricular muscle must overcome to eject blood . The greater the aortic / pulmonary pressure , the greater the after load on the left / right ventricle , respectively . Following Laplace 's law , the tension upon the muscle fibers in the heart wall is the pressure within the ventricle multiplied by the volume within the ventricle divided by the wall thickness ( this ratio is the other factor in setting the afterload ) . Therefore , when comparing a normal heart to a heart with a dilated left ventricle , if the aortic pressure is the same in both hearts , the dilated heart must create a greater tension to overcome the same aortic pressure to eject blood because it has a larger internal radius and volume . Thus , the dilated heart has a greater total load ( tension ) on the myocytes , i.e. , has a higher afterload . This is also true in the eccentric hypertrophy consequent to high intensity aerobic training . Conversely , a concentrically hypertrophied left ventricle may have a lower afterload for a given aortic pressure . When contractility becomes impaired and the ventricle dilates , the afterload rises and limits output . This may start a vicious circle , in which cardiac output is reduced as oxygen requirements are increased . </P>
<P> Afterload is the stress in the wall of the left ventricle during ejection . In other words , it is the end load against which the heart contracts to eject blood . Afterload is readily broken into components : one factor is the aortic pressure the left ventricular muscle must overcome to eject blood . The greater the aortic / pulmonary pressure , the greater the after load on the left / right ventricle , respectively . Following Laplace 's law , the tension upon the muscle fibers in the heart wall is the pressure within the ventricle multiplied by the volume within the ventricle divided by the wall thickness ( this ratio is the other factor in setting the afterload ) . Therefore , when comparing a normal heart to a heart with a dilated left ventricle , if the aortic pressure is the same in both hearts , the dilated heart must create a greater tension to overcome the same aortic pressure to eject blood because it has a larger internal radius and volume . Thus , the dilated heart has a greater total load ( tension ) on the myocytes , i.e. , has a higher afterload . This is also true in the eccentric hypertrophy consequent to high intensity aerobic training . Conversely , a concentrically hypertrophied left ventricle may have a lower afterload for a given aortic pressure . When contractility becomes impaired and the ventricle dilates , the afterload rises and limits output . This may start a vicious circle , in which cardiac output is reduced as oxygen requirements are increased . </P>
the tension or resistance that the ventricle must overcome to eject into systemic circulation
the tension or resistance that the ventricle must overcome to eject into systemic circulation
Afterload
Afterload