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

Heart 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 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 Failure

Heart Failure Diastolic 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 Failure

Heart Failure

Heart 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.