Lecture 18: Physiology/ Pharmacology/ Management of heart failure Flashcards
What is heart failure characterized by?
Impaired cardiac pumping such as the heart is unable to pump adequate amount of blood to meet metabolic needs.
What can heart failure result from?
Any structural or functional cardiac disorder that impairs the ability of the ventricle to eject blood or to fill with blood.
What are other words for heart failure?
- Chronic heart failure
- Congestive cardiac failure
- Congestive heart failure
What are the signs and symptoms of heart failure?
- Shortness of breath
- Excessive tiredness
- Leg swelling
What are the underlying causes and risk factors for heart failure?
- Ischemic heart disease
- Hypertension
- Myocardial infarction
- Valvular heart disease
- Congenital heart disease
- Dilated cardiomyopathy
What is congestive heart failure?
Left sided failure
- its the most common form
- Blood backs up through the left atrium into the pulmonary veins
How is cardiac output calculated?
heart rate x stroke volume
What is stroke volume?
The volume of blood pumped from each ventricle
What is stroke volume affected by?
- Preload
- Afterload
- Ventricular contractility
What happens when preload increases?
- End diastolic volume increases
- Resulting in an increase stroke volume
What happens when afterload increases?
- End systolic volume increaeses
- Resulting in a decreased stroke volume
What happens if contractility is increased?
- End systolic volume is reduced, resulting in an increse in stroke volume
How does heart rate affect cardiac output?
The higher the heart rate, the higher the cardiac output
How does excessivly high heart rate affect cardiac output?
Diastolic filling time begins to fall, causing stroke volume and cardiac output falls
What is preload?
The amount of fibre stretch in the ventricles at the end of diastole (so before the next contraction)
What is preload directly related to?
Ventricular filling
What does a higher end diastolic volume imply?
Higher preload
What does preload increase with?
- increase in blood volume
- Vasodilation
What does preload decrease with?
- Loss in blood volume
What is starlings law?
Describes the relationship between preload and cardiac output
How does the stretch of the cardiac muscle fibers affect the force of contraction?
The greater the stretch, the greater the force of contraction
What does excessive preload result in?
Excessive stretch, reduced contraction, reduced systolic volume/ cardiac output