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)
Define systolic dysfunction
The impaired ability of the heart to contract
Define diastolic dysfunction
Impairment of the filling of the heart.
What does heart failure cause?
Systolic dysfunction
Diastolic dysfunction
Increases ADH secretion
Inhibits nitric oxide secretion
What causes heart failure?
Ischaemic heart disease is the most common cause of heart failure
– myocardial infarction, valve rupture, hypertension (pulmonary and systemic), congenital heart diseases, anaemia, chronic lung disease
What can happen to the heart muscle itself to compensate in heart failure?
Hypertrophy of cardiac muscle causes a decreased ventricular volume which worsens the decreased cardiac output causing the heart to remodel and dilate.
What are the signs and symptoms of left heart failure?
Fatigue (C output doesn’t meet needs)
Exertional dyspnoea (cant meet increased demand)
Pulmonary oedema (increased venous pressure …)
Displaced apex beat and cardiomegaly (due to LV hypertrophy)
Tachycardia (sympathetic response to decreased CO)
Give some characteristics of pulmonary oedema
Increased venous pressure –> increased hydrostatic pressure in capillaries –> fluid moves into tissue
PULMONARY CRACKLES: fluid collects in the bottom of the lungs when upright
ORTHOPNOEA: fluid distributes when lying down, causing BREATHLESSNESS from impaired gas exchange
CYANOSIS: impaired gas exchanges leads to hypoxaemia
Why is fatigue presents in right heart failure?
Decreased flow to the lungs results in hypoxaemia due to a ventilation/perfusion mismatch. Insufficient oxygen for metabolic needs.
Why is breathlessness present in right heart failure?
Decreased oxygenated blood enters systemic circulation. Hyperventilation results in order to increase the partial pressure of oxygen.
What causes raised jugular venous pressure?
Failure of right side of the heart to pump in right heart failure causes a rise in venous pressure and distension of the jugular veins.
What is pitting oedema and why does it occur?
Oedema that when you press down on, leaves and indentation in the skin.
It is due to increased venous pressure –> increased hydrostatic pressure in capillaries –> fluid leaks out into the interstitium
Why does hepatomegaly occur in right heart failure?
Bloods backs up into inf. vena cava causing congestion of the hepatic veins –> hepatic engorgement.
What areas in the body are targeted fro drugs to help regulate the cardiac output?
KIDNEYS: regulate blood volume (Na and H20 reabsorption)
ARTERIOLES: regulate blood pressure
MYOCARDIUM: regulates force of contraction (depends on degree of stretch)
SAN: regulates heart rate
What are the main changes that are made in order to manage heart failure?
Lifestyle – diet, exercise
Drugs if lifestyle changes have been changed and are having little/need more of an effect
1. antihypertensives
2. beta-blockers to reduce cardiac workload
3. positive inotropes
4. anti-arrhythmic drugs
Name some anti-hypertensive drugs
alpha-1 antagonists
Diuretics e.g. loop diuretics & spironolactone
ACE-inhibitors
What happens in right heart failure?
Right heart does not work properly and leads to an increased venous pressure causing oedema due to increased venous pressure increasing the hydrostatic pressure in the capillaries.
What is nocturia and why does it occur?
Frequent urination throughout the night.
Due to fluid which has been built up in ankles/legs returns to the blood stream when lying down
What are the characteristic signs of right heart failure?
Pitting peripheral oedema Raised jugular venous pressure Fatigue Hepatomegaly Breathlessness Ascites
Generally, what does left heart failure have an effect on?
Lung function
Generally, what does right heart failure have effects upon?
Differing areas in the systemic circulation
What tends to me the main cause of right heart failure?
Tends to be secondary to left heart failure
What are some common signs of left heart failure?
Increased breathing rate (tachypnea) and increased work of breathing
When does cyanosis occur in left heart failure?
It is quite rare as it is a late sign of severe pulmonary oedema
What are the main causes of congestive heart failure?
Ischaemic heart disease Cigarette smoking Hypertension Obesity Diabetes Valvular heart disease (usually older populations)
How is the severity of heart failure determined and how are they differentiated?
Heart failure is divided into classes depending on the the impact on life and physical exertion
Class 1 = lowest severity
Class 4 = more severe
Describe the different classifications of heart failure
Class 1 = No symptomatic limitation of physical activity
Class 2 = Slight limitation of physical activity with ordinary physical activity resulting in symptoms. Have no symptoms at rest
Class 3 = Marked limitation of physical activity with less than ordinary activity causing symptoms
Class 4 = Unable to carry out physical activity without symptoms and may have symptoms at rest. Increased discomfort with any kind of physical activity
What stimulates renin release from the kidneys?
What does renin do?
Drop in blood pressure
Catalyses conversion of angiotensin to angiotensin 1
What effects does the sympathetic nervous system have on blood vessels?
Activates the alpha-1 receptor which causes vasoconstriction of blood vessels, increasing blood pressure which increase the after-load and the preload of the heart therefore increasing the whole workload of the heart
Also affects beta-1 receptors in order to increase the chronotropy and inotrophy of the heart
What affect do ACE inhibitors have?
Prevents conversion of angiotensin 1 to angiotensin 2. Has an indirect vasodilatory and diuretic effect, which decrease the workload on the heart.
Why can increasing the action of the RAAS be detrimental?
Angiotensin 2 has a number of effects on certain organs
Increases atherosclerosis, vasoconstriction, vascular hypertrophy, endothelial dysfunction –> STROKE and HYPERTENSION
LV hypertrophy, fibrosis and apoptosis in the heart –> MI
Can cause GFR, Proteinuria, Aldosterone release and glomerular sclerosis which can lead to RENAL FAILURE
