Drug Management of Heart Failure: Chronic Heart Failure Acute Pulmonary Oedema Flashcards
What happens under normal circumstances when there is an activation of the sympathetic nervous system in response to a fall in blood pressure?
Sympathetic nervous system activation which will drive positive chrono and inotropic responses as well as positive trophic response.
The kidney will produce much more renin. (salt and water retention)
Peripheral vasoconstriction
Cardiac remodelling
What is cardiac remodelling?
A trophic response to make the heart grow.
What symptoms does sympathetic activation associated with fall in cardiac output during heart failure result in?
Increase in peripheral vascular resistance
Increase in cardiac afterload
Causes cardiac arrhythmia
What symptoms does RAAS activation associated with fall in cardiac output during heart failure result in?
Peripheral vascular resistance
Salt and water retention
What symptoms does raised pulmonary venous pressure associated with heart failure result in?
Dyspnoea and pulmonary oedema
What symptoms does raised central venous pressure associated with heart failure result in?
Peripheral and viceral oedema
What symptoms does reduced cardiac output associated with heart failure result in?
Impaired organ function, fatigue
What symptoms does peripheral vasoconstriction associated with heart failure result in?
Impaired organ function and fatigue
What symptoms does cardiac remodelling associated with heart failure result in?
Functional deterioration
Earlier mortality
What is afterload?
Obstruction blood faces when ventricle is contracting
What is preload?
Pressure from the venous system
Name some renin-angiotensin inhibitor families:
AtII acts on AT1 receptor which can be blocked by “sartan” blockers
ACE1 inhibitors are “pril”
Name an aldosterone blocker:
Spironolactone which blocks myocardial remodelling and blocks sodium, potassium and water retention
What does the heart do in response to the RAAS system?
Aldosterone has trophic effects on the ventricle
Why are beta1 adrenoceptors blocked pharmacologically?
To prevent cardiac remodelling
What are the most predictable adverse effects of beta blockers?
Bronchospasm (due to beta 2 receptors on bronchial smooth muscle.) [not to be used in people with airway obstructions]
Bradycardia
Acute worsening heart failure [should not be used for acute attacks because it worsens heart failure short term]
Why are diuretics used for heart failure?
To reduce peripheral and pulmonary oedema
Name a loop diuretic:
Frusemide
Name an aldosterone blocker:
Spironolactone
What drug can be used in short term to create an inotropic effect?
Digoxin
What does digoxin do?
It is a cardiac glycoside due to presence of 3 sugars. Water soluble and renally excreted.
It blocks sodium potassium pump reducing the sodium and potassium gradient
It makes less efficient Ca2+ exchange increasing intracellular calcium because the calcium sodium gradient exchanger can take calcium out less effectively. This results in more calcium entering the sarcoplasmic reticulum thus causing an inotropic effect while not being chronotropic.
More efficient myocyte contraction
What else can result from digoxin interference?
It decreases heart rate and slows down AV conduction.
It affects the cardiovascular center in the brain that affects vagal tone by making the vagus nerve less effective.
It interferes with potassium flow by decreasing the potassium gradient and so resting membrane potential ends up being much higher. This means too much digoxin results in arrhythmia.
What clinical symptoms indicate a need to stop using digoxin?
Serious arrhythmias (due to hypokalaemia)
Nausea, confusion, and visual neurological symptoms.
What is the half life of digoxin? What does this mean?
1 day. it will take some time before being completely out of the body.
