Heart Failure -- Session 11 Flashcards
Define heart failure
A state in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure
Give some chronic causes of L heart failure
Systemic hypertension Arrhythmias Coarctation of the aorta Anaemia Thyrotoxicosis Ischaemic heart disease
Give some chronic causes of R heart failure
Pulmonary hypertension Arrhythmias Chronic lung disease Chronic pulmonary/tricuspid valve dysfunction Left to right shunt Left heart failure
Give some acute causes of R heart failure
Pulmonary embolism
Rupture of tricuspid valve cusp
Give some acute causes of L heart failure
Myocardial infarction
Rupture of mitral or aortic valve
What are some causes on congestive heart failure?
Thyrotoxicosis
Lesions of the aortic and mitral valves
Anaemia
What are the 6 compensatory mechanisms for heart failure?
SNS activation RAAS activation Anti-diuretic hormones Nitric-oxide Prostaglandin E2 and I2 Hypertrophy of cardiac muscle
How is the sympathetic nervous system activated?
Falls in BP and blood volume are detected by baroreceptors in the aortic arch and carotid sinus
What does the SNS do to compensate in heart failure?
Increased HR and force of contraction –> increase cardiac output and then increasing the work load of the heart
Secretes renin to activate RAAS
What does vasoconstriction of the arterioles of?
increases the blood pressure and the after load
How can left heart failure cause right heart failure?
Left heart failure raises pulmonary arterial pressure which the causes right heart failure
What is the name used when both ventricles are affected in heart failure?
Congestive heart failure
Why are the sympathetic nervous system and the renin-angiotensin-aldosterone-system activated in heart failure?
What affect do they have?
To maintain cardiac output
They cause the struggling heart to work harder
How if the RAAS activated?
Caused by reduced blood flow to the kidneys and SNS causing renin secretion.
Causes endothelin secretion by vascular endothelial cells. Leads to renal vasoconstriction which activates RAAS
What does the RAAS do?
Angiotensin is converted to angiotensin 1 by renin.
Angiotensin 1 is converted to angiotensin 2 by angiotensin converting enzyme.
Angiotensin 2 promotes vasoconstriction and aldosterone release from the adrenal cortex.
What effects does aldosterone have?
Increases BP, NA and H2O retention by the kidneys causing and increase in blood volume, increasing venous return and stroke volume.
Why are diuretics used in heart failure?
You want to prevent water retention and increased blood volume in order to limit oedema
When does peripheral oedema occur?
Due to right-sided heart failure.
Failure to pump correctly causes and increase in venous pressure and capillary pressure, forcing fluid out into the tissues.
When does pulmonary oedema occur?
Due to left-sided heart failure.
Causes an increased left-atrial pressure which also causes a rise in pressure of the vessels in the pulmonary circulation.
(Also increases pulmonary artery pressure due to low resistance of these vessels)