Frank-Starling Mechanism Frank-Starling Mechanism • The change of heart’s force of contraction in response to

change in venous return.• During exercise, venous return i.e. blood that returns to the

heart increased which then causes increase to stroke volume.

• Frank-Starling mechanism tells how change in venous return will alters the stroke volume.

• Increased venous return increases the ventricular filling (end-diastolic volume) and therefore preload, which is the initial stretching of the cardiac myocytes prior to contraction. Myocyte stretching causes an increase in force generation. This mechanism enables the heart to eject the additional venous return, thereby increasing stroke volume.

Frank-Starling Mechanism Frank-Starling Mechanism

Frank-Starling Mechanism Frank-Starling Mechanism

Heart FailureHeart Failure• Heart Failure is inability of the heart to fill with

blood or pump blood sufficiently through the body.

• Thus, there will be inadequate supply of oxygen to peripheral tissues and organs.

• Under perfusion of organs leads to reduced exercise capacity, fatigue, and shortness of breath. It can also lead to organ dysfunction (e.g., renal failure) in some patients.

Heart FailureHeart Failure• Heart failure results in decrease in cardiac output due to

decline in stroke volume. • It might be caused by systolic dysfunction and diastolic

dysfunction.Systolic Dysfunction• Impaired ventricular contraction.• Loss of cardiac inotropy or decreased contractility, thus

heart cannot contract normally.• Weak muscle could not pump blood in sufficient amount.• Ventricle usually enlarged.

Heart FailureHeart Failure

Heart FailureHeart FailureDiastolic Dysfunction• Impaired ventricular filling.• Reduction ventricular compliance will decrease EDV and

increase EDP.• So, less volume of blood in the ventricle which cause

decline in stroke volume.

Heart FailureHeart Failure

Heart FailureHeart Failure

Heart FailureHeart Failure• Heart failure will cause rise in left atrial and pulmonary

venous pressure.• This will lead to pulmonary congestion and edema.• Pulmonary edema is accumulation of fluids in the lungs.• Other causes of heart failure is coronary artery disease,

myocardial infarction and valve disease.• Treatment involves use of several types of drugs.