Heart failure Flashcards
Heart failure
Occurs when cardiac output is unable to meet demands, the heart then tries harder to compensate for this, leading to cardiac hypertrophy
Poor prognosis; 50% die within 5 years
Causes of heart failure
- Cardiac variables
- Pre-load variables
- Post-load variables
Cardiac variables
- Defects in the myocardium itself
- Coronary artery disease
- Cardiotoxicity (e.g. chemotherapy)
- Congenital defects
Pre-load variables
Occur in the circulatory system before blood reaches the heart
- Increased venous pressure
- Pulmonary hypertension
- Increased ventricular diastolic volume & pressure
- Faulty valves
- Congenital defects
Post-load variables
Occur in the circulatory system after the blood has left the heart
-Increased peripheral resistance
This is linked with obesity; more adipose tissue means that there is a greater distance of capillaries that blood must be pushed through
Symptoms of heart disease
- Oedema
- Breathlessness
- Decreased perfusion
- Fatigue
- Cardiac hypertrophy
Oedema
Oedema refers to a build-up of tissue fluid
Usually, each contraction of the heart causes a wave of tissue fluid to flow over nearby tissues , excess fluid drains into the lymph
In heart disease, the heart beat loses strength and so tissue fluid accumulates
Breathlessness
Occurs in heart disease because oedema also occurs in the lungs
Gas exchange then becomes less efficient
Positive inotropes
A drug that increases the force of heart contractions
These drugs force the heart to work harder, this allows for better perfusion of tissues, alleviating symptoms
May speed up the progression of heart disease
Negative inotropes
Drugs which decrease the force of heart contractions
ACE inhibitors
Inhibit the formation of angiotensin II
This increases tissue perfusion and decreases blood pressure
Help to reduce oedema and breathlessness
Decreases pre & post-load variables
Diuretics
Reduce blood volume by increasing fluid loss, this lowers blood pressure
Relieves peripheral oedema and improves breathlessness
Decreases pre & post-load variables
Vasodilators
Increase the volume of the circulatory system to decrease blood pressure
When given in acute heart failure, can slow the progression of the disease
Decrease pre & post-load variables
Beta blockers
Negative inotropes
Only given in mild heart failure
Are a counter-intuitive treatment but prevent harmful activation of the sympathetic nervous system and RAAS to improve prognosis
B1-adrenoceptor antagonists
Positive inotropes
Increases cardiac contractility and tissue perfusion
Used to treat acute, potentially reversible heart failure
