Physiology of heart failure

Question 1

What is chronic heart failure?

Answer 1

When the heart is unable to pump blood around the body.

Question 2

What is ejection fraction?

Answer 2

Volume ejected / Total volume filled up in the ventricle

Question 3

What is a normal ejection fraction?

Answer 3

Normal is >55%

Question 4

How is heart failure classified?

Answer 4

Heart failure is classified when ejection fraction <40%

Question 5

What are the types of heart failure?

Answer 5

Systolic = impaired ventricular contraction
Ventricular = impaired ventricular relaxation
Right (Cor-pulmonale) vs Left-sided

Question 6

Name 4 causes of systolic HF
Explain the pathophysiology of systolic HF

Answer 6

1. Heart muscle disease - e.g. cardiomyopathy
2. Reduced blood supply to the heart - e.g. CAD
3. Valvular disease - e.g. Aortic stenosis
   Arrhythmias - e.g. AF

All of these can lead to heart failure as they reduce the pumping efficiency of the heart muscle. This leads to the heart muscle having to work harder and puts strain on the heart and overtime the ventricles cannot contract properly.

Question 7

Name 2 causes of diastolic HF
Explain the pathophysiology of diastolic HF

Answer 7

1. Chronic HTN - increased BP in your vessels means the heart has to work harder and so ventricular hypertrophy occurs
2. Aortic stenos - heart muscle bulks so it can pump against stenosed valve.

The underlying pathophysiology is due to ventricular hypertrophy as the heart muscle is bigger and so leads to less room for blood to be filled. The bigger muscles are stiffer and so do not stretch as much.

Question 8

What is diastolic heart failure with preserved ejection fraction?

Answer 8

With diastolic heart failure, the total volume of blood in ventricles decreases but also at the same time, you can get reduced ejection fraction and therefore your ejection fraction may be normal.