Download Lecture Note 3 - Heart Failure

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.