16 - Heart Failure Flashcards
What is the definition of heart failure?
The heart fails to maintain an adequate circulation for he needs of the body despite an adequate filling pressure
What can heart failure be due to?
- Inability to fill properly
- Inability to contract properly
In terms of conditions, what are the most common conditions causing heart failure?
- Most common: IHD
- MI damaging left ventricle, aortic stenosis, chronic hypertension
- Rare: sepsis, severe anaemia, thyrotoxicosis (high output heart failure) (treat underlying cause)
What are the factors affecting stroke volume?
- Pre-load
- After-load
- Myocardial contractility (healthy heart muscle)
What is ejection fraction, what is the normal value and how is it measured?
- EF= (SV/EDV) X 100
- 50-70% normal, any less than 40% suggests LV not pumping properly and heart failure
- Echocardiography
Draw a Frank Starling curve and explain it’s shape.
- Intrinsic property of myocytes the greater they are stretched the greater they contract
- Falls due to overstretching of the filaments
If sympathetic innervation to the heart increases what happens to the Starling curve?
Why might someone be in heart failure but still have an ejection fraction of 70%?
May have an issue with filling, not contractility, where the ventricle is recieving less blood so ejecting less
HFrEF
Why is cardiac output reduced during heart failure?
- Reduced pre-load
- Reduced myocardial contractility
- Increased afterload
What are some filling and contractility problems with the heart?
How can you classify heart failure in terms of ejection fraction?
- Normal >50%
- HFrEF (most common)
- HFpEF
How can you classify heart failure accoding to ventricles involved?
- Left (most common)
- Right (rare)
- Biventricular/Congestive (when both involved)
What are the causes of right sided heart failure?
- Mainly left sided heart failure
- Secondary to chronic lung diseases (called cor pulmonale)
- Isolation
What is Cor Pulmonale ?
- Abnormal enlargement of the right side of the heart as a result of disease of the lungs or the pulmonary blood vessels
- Leads to right sided heart failure
What happens to Frank Starling’s curve in heart failure?
In heart failure, what happens to the CO, what does the body do to try and combat this, and what is the issue with this?
- Falls so neurohumoral activation
- SNS, RAAS, ADH activated due to drop in b.p and renal perfusion to increase b.v and therefore b.p
- Cause the workload of the heart to increase and increases venous congestion
How does the body positively combat heart failure?
Late stage heart failure, atria stretches and this causes ANP and BNP to be released. They cause natiuresis, inhibit renin secretion and promote vasodilation. However, not enough to overcome effects of other symptoms
What happens in heart failure to cause oedema?
The hydrostatic pressure at the venule end increases as there is congestion from the atria, therefore less tissue fluid being reabsorbed
What is the difference in the signs and symptoms of left and right heart failure?
- Left: pulmonary oedema
- Right: peripheral tissue oedema
MAY HAVE MIXTURE OF BOTH AS MAY HAVE CONGESTIVE
Why do people get orthopnea with heart failure?
- When you lay flat there is an increase in venous return to the right side of the heart as no gravity
- Left ventricle may be in failure then cannot cope with increased demand so there is pulmonary congestion
- Therefore, increase in hydrostatic pressure causes exudate and pulmonary oedema so air spaces filled with fluid not air so diffusion cannot occur
What does pulmonary oedema look like on chest x-ray?
Fluffy lungs as fluid
Draw a diagram to show how myocardial damage leads to deleterious effects on the heart.
