CVS S11 - Heart Failure Flashcards
(25 cards)
Give some common causes of heart failure
Ischaemic heart disease Arrhythmia Hypertension Dilated cardiomyopathy (due to pregnancy, alcohol, drugs, poisoning) Valvular/congenital heart disease Pericardial disease Hypertrophic cardiomyopathy Restrictive cardiomyopathy (eg amyloidosis) High output heart failure
Define heart failure
A state in which the heart fails to maintain adequate circulation for the demand of the body, despite adequate filling pressure
Describe and explain the relationship between end diastolic pressure and cardiac output with increasing severity of heart failure
Starlings law states that CO increases with EDP up to a plateau where the ventricles cannot hold any more blood.
In heart failure, the heart cannot produce the same amount of force for a given level of force, so CO can actually decrease with increasing EDP
Describe class I heart failure
No symptomatic limitation of physical ability
Describe class II of heart failure
Slight limitation of physical ability
Ordinary physical activity results in symptoms
No symptoms at rest
Describe class III of heart failure
Marked limitation of physical activity
Less than ordinary physical activity results in symptoms
No symptoms at rest
Describe class IV of heart failure
Inability to carry out any physical ability without symptoms
May have symptoms at rest
Discomfort increases with any degree of physical activity
Describe congestive heart failure
When both sides (left and right) of the heart are in heart failure
How can lung disease cause right heart failure?
Chronic pulmonary disease can increase the resistance in the lung, meaning the right heart has to pump harder
How does congestive heart failure usually occur?
The left heart fails, then blood backs up in the pulmonary vein and lungs, increasing the pressure and so the force of contraction required by the right ventricle, so right heart failure occurs secondary to left.
What groups can heart failure be divided into?
Systolic heart failure Diastolic heart failure Left sided heart failure Right sided heart failure Congestive or biventricular heart failure
What are the signs and symptoms of left sided heart failure
Fatigue
Shortness of breath upon exertion or lying flat (may wake from sleep)
Tachycardia
Cardiomegaly (and so displaced apex beat)
3rd and sometimes 4th heart sounds (gallop rhythm)
Functional murmur of mitral valve regurgitation
Basal pulmonary crackles
Peripheral oedema
What are the common signs and symptoms of right sided heart failure?
Fatigue Dyspnoea Anorexia Nausea Raised JVP Tender, smooth, hepatic enlargement Pitting oedema Ascites Pleural effusion
What are the common causes of right sided heart failure?
Most often secondary to left sided heart failure Chronic lung disease Pulmonary hypertension or embolism Pulmonary/tricuspid valve disease Left to right shunts (ASD/VSD) Isolated right ventricular myopathy
Broadly, how is the renin-angiotensin-aldosterone system (RAAS) involved in heart failure
The RAAS system is activated in cardiac failure in an attempt to maintain cardiac output BUT it has the effect of making an already struggling heart work harder
Describe in detail the activation of the RAAS
Decreased BP stimulates a release of renin from the kidneys
Renin catalyses the conversion of angiotensin to angiotensin I
Angiotensin I is converted to angiotensin II by ACE
Angiotensin II is a powerful vasoconstrictor and promotes the release of aldosterone from the kidneys
Aldosterone causes water and salt retention, causing increased blood volume
Describe the involvement of the sympathetic nervous system in heart failure
The sympathetic NS causes vasoconstriction by the stimulation of the α1 receptor.
This increases blood pressure which increases the workload of the heart by increasing preload and after load
Sympathetic stimulation of the hearts β1 receptors will cause an increase in both chronotropy and inotropy
What drugs are useful in the treatment of heart failure?
ACE-inhibitors Diuretics β-blockers Ca channel blockers Organic nitrates Cardiac glycosides
How do ACE-inhibitors work?
They prevent the conversion of angiotensin I to angiotensin II
They therefore have a vasodilatory and diuretic effect, which is useful for reducing the workload of the heart
Control cardiac output
How are diuretics useful in the treatment of heart failure?
They reduce blood volume and thus reduce oedema
Control cardiac output
How are β-blockers useful in the treatment of heart failure?
They prevent sympathetic stimulation of β receptors of the heart so reduce inotropy and chronotropy
Control cardiac output
How are Ca channel blockers useful in the treatment of heart failure?
Reduce contractility of the myocardium
How are organic nitrates useful in the treatment of cardiac failure?
They act as veno/vasodilators so reduce BP
This reduces preload and after load so reduces the workload of the heart
How are cardiac glycosides useful for the treatment of heart failure?
Inhibits the Na/K pump
Raised intracellular Na inhibits NXC
Therefore intracellular Ca is increased
So contractility is increased
