Heart Failure and Cardiac Arrhythmias Flashcards
What is heart failure?
The inability of the heart to deliver enough blood to meet the body’s needs/supply the body’s demands
What characterises the clinical syndrome of heart failure? (3 points)
Breathlessness
Oedema (usually ankles)
Fatigue
Which side do the pulmonary vein and aorta belong to in the heart?
Left
Which side do the pulmonary artery and superior/inferior vena cava belong to in the heart?
Right
Which atrioventricular valve is on the left?
Mitral valve
Which atrioventricular valve is on the right?
Tricuspid valve
What are the main indications of acute heart failure?
Pulmonary oedema with breathlessness at rest
Chronic heart failure has several underlying ______ causes. It is aggravated by ___________ _______-_________ regulation. It is associated with ______ mortality. Patients have a high risk of complications of procedures involving __________ __________.
Cardiac, dysfunctional neuro-hormonal, high, general anaesthesia
What happens in left-sided heart failure?
Raised pulmonary venous pressure
Pulmonary oedema
Pulmonary venous congestion
What happens in right-sided heart failure?
Peripheral oedema
Raised jugular venous pressure
Systemic venous congestion
What are the possible cardiac causes of heart failure? (4 points)
Heart muscle disease such as cardiomyopathy or ischaemic heart disease causing left ventricular systolic dysfunction where less than 40% of blood is pumped out of the left ventricle
Excessive volume load due to valvular regurgitation
Excessive pressure load due to hypertension, aortic stenosis, pulmonary hypertension
Sustained abnormal rhythm such as tachycardias, bradycardias
What are the 2 main non-cardiac causes of heart failure syndrome or what aggravates heart failure?
Excessive demand in high output caused by arteriovenous shunts (may be present in patients undergoing haemodialysis), anaemia, hyperthyroidism
Fluid overload from excessive IV therapy or renal failure (as kidney removes water from body)
What are the 4 most common causes of heart failure?
Ischaemic heart disease (which may lead to myocardial infarction resulting in left ventricular weakness)
Hypertension (excessive pressure load)
Valvular heart disease (valve stenosis and valve regurgitation causing excessive volume load)
Chronic obstructive pulmonary disease
What physical signs are examined in patients with suspected heart failure? (8 points)
Pulmonary oedema - breathless, cyanosis, basal lung crackles on auscultation
Peripheral oedema - pitting (leaves an indent and doesn’t spring back after pressing firmly for a few minutes)
Ascites
Pleural effusions
Raised jugular venous pressure
Irregular pulse
Heart murmur
Anaemia
What investigations can be done to assess cardiac causes of heart failure?
Chest X-ray (shows if the heart is enlarged or if lungs are congested with fluid)
ECG (shows signs of MI/previous MI and atrial fibrillation)
Echocardiogram (ultrasound; best test; shows how well the chambers are contracting in real-time)
What investigations can be done to assess non-cardiac causes of heart failure? (3 points)
Urea and electrolytes test (check kidney function)
Full blood count (check for anaemia)
Thyroid function test
One of the conflicting neuro-humoral compensatory mechanisms is how reduced cardiac output and blood pressure resemble dehydration or haemorrhage, therefore activating the ______-______-________ system to retain salt and water as well as the ________ nervous system to vasoconstrict (maintain blood pressure) and stimulate heart rate (maintain cardiac output). These are fine during the acute phase but will become harmful in the chronic phase as excess adrenaline can overdrive the heart and damage it, and the RAA system can lead to oedema which we wanted to avoid in the first place.
Renin-angiotensin-aldosterone, sympathetic
Another conflicting neuro-humoral compensatory mechanism: increased intracardiac pressures detected by ‘______ receptors’ in the heart resembles fluid overload causing atrial and ‘brain’ ________ peptides coming from ventricles to stimulate sodium excretion
Stretch, natriuretic
What does reduced renal blood flow stimulate?
Secretion of renin from the kidney
What does renin stimulate?
Angiotensin-Converting Enzyme (ACE)
What does ACE catalyse?
Production of angiotensin II from angiotensin I
How does angiotensin II work?
Acts as a vasoconstrictor through the AT1 receptor and stimulates aldosterone secretion from the adrenal cortex
What is aldosterone and what does it do?
A mineralocorticoid that increases sodium retention in the kidney
What does sodium retention indirectly do?
Stimulates water retention through vasopressin
(antidiuretic hormone) from the posterior pituitary
What does activation of the renin-angiotensin-aldosterone system result in? (3 points)
Increased circulating volume
Oedema
Vasoconstriction
What are the two main hormones in the sympathetic system?
Adrenaline and noradrenaline
What cardiac-related effects do adrenaline and noradrenaline cause via the sympathetic system?
Stimulate heart rate and contractility
Vasoconstrict
Thereby raises low blood pressure
How does long-term vasoconstriction damage the heart?
Increases the resistance against which the heart has to work
What are the 7 different types of medications commonly used by patients with heart failure?
ACE inhibitors —pril
Angiotensin II receptor blockers —sartan
Aldosterone antagonists - spironolactone and eplerenone
Beta blockers —olol
Vasodilators - hydralazine, nitrates
Loop diuretics
New sacubitril-valsartan treatment
What do loop diuretics do?
Treat symptoms due to fluid overload (make kidney get rid of salt and water)
How does the sacubitril-valsartan treatment work?
Blocks both the AT1 receptor and neprilysin - an enzyme that degrades natriuretic and vasoactive peptides
What are the non-pharmacological treatment options for heart failure?
Cardiac resynchronisation pacemaker for severe left ventricular systolic dysfunction with wide QRS
Cardiac surgery - valve replacement, repair, transplantation
Why does left-sided heart failure cause pulmonary oedema and dyspnoea?
As left ventricle fails, blood dams back in the pulmonary veins where the venous pressure rises causing the alveoli in the lungs to fill with fluid
What are the symptoms of left-sided heart failure?
Dyspnoea
Cough
Pink frothy sputum
Paroxysmal nocturnal dyspnoea
What are the symptoms of right-sided heart failure?
Subcutaneous oedema in the ankles and sacrum
Fatigue
Abdominal distension and discomfort from hepatic congestion and ascites
The conduction system
Sino-atrial node
Atrial tissue
Atrioventricular node
Ventricular conducting tissue - His-Purkinje system
What do the waves represent in the electrocardiogram (ECG)?
P wave = atrial contraction
QRS complex = ventricular contraction
T wave = ventricular repolarisation
What is the range of normal heart rate?
between 60 to 100 bpm
What is the range of heart rate in tachycardia?
> 100 bpm
What is the range of heart rate in bradycardia?
< 60 bpm
What is the most common rhythm disturbance?
Atrial fibrillation
Although sinus tachycardia (normal P waves on ECG) can be a normal response to exercise or emotion, what could it also be indicative of?
Hyperthyroidism
Hypovolaemia
Fever
Heart failure
What happens in atrial fibrillation (no P waves)?
Uncoordinated and ineffectual atrial contraction
Resulting in a rapid and irregular ventricular rate
Reduces efficiency of the heart (heart failure)
What is the heart rate of ventricular tachycardia?
Faster than 140 bpm
What disease is ventricular tachycardia often associated with?
Ischaemic heart disease
What can ventricular tachycardia sometimes be caused by?
Drugs
How would the ECG look for ventricular tachycardia?
QRS complexes wider than normal
Sinus bradycardia may be normal at rest in a young person, but what can it also be caused by?
Drugs
Hypothyroidism
What is atrioventricular block also known as?
Heart block
What is impaired when an atrioventricular block occurs?
Conduction of the impulse from the atria to the ventricles
What is extrasystole?
Single extras beats arising from atria or ventricles
What is ventricular fibrillation, and what does it cause?
Uncoordinated and ineffective electrical activity of the ventricles
Causes cardiac arrest
Rapid loss of consciousness and death within minutes
What is asystole, and what can it cause?
Absence of electrical activity and contraction (there may be evidence of atrial activity)
Causes cardiac arrest
Sudden loss of consciousness and death
What is usually used to treat bradycardias?
Pacemakers
What is usually used to prevent ventricular arrhythmias such as ventricular tachycardia and ventricular fibrillation?
Implantable defibrillators
What are the treatment options for atrial fibrillation?
Rate-controlling drugs - digoxin or beta blockers
Anticoagulation with warfarin or DOAV to reduce the risk of stroke from embolisation of left atrial thrombus
What does the anti-arrhythmic drug, amiodarone, treat?
Atrial fibrillation
In emergency situations, what is the electrical direct current (DC) cardioversion used to treat?
Ventricular fibrillation in a cardiac arrest
(Chronic) atrial fibrillation
Ventricular tachycardias
Some arrhythmias can be treated by _______ of abnormal electrical tissue in the heart during ___________ studies, effecting a permanent cure.
Ablation, electrophysiological
What are the 5 drugs classes commonly used for heart failure?
Inotropes
Diuretics
Beta-blockers
ACE inhibitors
Angiotensin receptor blockers
What drugs classed under inotropes mimic the effect of adrenaline (positive chronotropic and positive inotropic effects)?
Adrenoreceptor agonists
How do adrenoreceptor agonists/inotropes work?
Increase the force of contraction of the heart (+ve inotropic) by stimulating cardiac β1 receptors
How do diuretics work?
Increase the amount of urine
How do beta-blockers work?
Stabilise the heart rhythm and improve haemodynamics
How do ACE inhibitors and angiotensin receptor blockers work?
Cause dilatation of blood vessels
Reduce work of contraction for the heart
Why should inotropes be given in continuous intravenous infusion via central line in ITU/CCU?
It has a very short half-life
What is digoxin?
Cardiac glycosides
Classed under inotropes
What are the actions of cardiac glycosides/digoxin?
Antiarrhythmic by enhancing the action of the vagus nerve to reduce the rate and conduction velocity in sinus and AV nodes
Inotropic/increase in contractility by increasing intracellular sodium and calcium
What is digoxin used to treat?
Supraventricular arrhythmias
Chronic atrial fibrillation
Heart failure (improves symptoms but not mortality)
How is digoxin eliminated (metabolised + excreted) from the body?
Predominantly by kidneys (renal)
But some by liver (hepatic)
How should people with impaired renal function be managed when prescribing digoxin?
Give lower doses otherwise may get high conc. of digoxin in the blood
What is the half-life of digoxin?
36 hours
Longer in renal failure
