Flashcards in Cardiac Arrhythmias Deck (135)
Where is the origin in a supraventricular arrythmia?
Above ventricle i.e. SA, atrial muscle, AV node or HIS node
What are ectopic beats?
Beats or rhythms that originate in places other than the SA node
Whta may cause single beats or take over and pace the heart, dictating its entire rhythm?
Name three supraventricular tachycardias?
1. Atrial fibrillation
2. Atrial flutter
3. Ectopic atrial tachycardia
Name two bradycardia (supraventricular arrhythmias)?
1. Sinus bradycardia
2. Sinus pauses
Name three atrio-ventricular node arrythmias?
1. AVN re-entry
2. Acessory pathway (e.g. WPW)
3. AV block - 1st, 2nd and 3rd degree
Name 4 ventricular arrythmias?
1. Premature ventricular complex (PVC)
2. Ventricular tachycardia
3. Ventricular fibrillation
What can abnormal anatomy e.g. left ventricular hypertrophy, accessory pathways and congenital HD cause?
What are two autonomic causes of arrythmias?
1. Sympathetic stimulation - nervousness, exercise, CHF, hyperthyroid
2. Increased vagal tone (bradycardia, heart block)
What are three metabolic causes of arrythmias?
1. Hypoxic myocardium: chronic pulmonary disease, PE
2. Ischaemic myocardium: acute MI, angina
3. Electrolye imbalances: imbalances of K, Ca, Mg
What inflammation cause is there of arrythmias?
Name a mutation of cardiac ion channels that can cause arrythmias?
The congenital long QT syndrome
What two conditions can alter automacitiy?
Ischaemia and catecholamines
What two things can cause re-entry?
WPW syndrome - accessory pathway tachycardia
What does hypothermia do to phase 4 slope?
What do hypoxia and hypercapnia do to phase 4 slope?
What does cardiac dilatation do to phase 4 slope?
What increases automaticity of neighbouring cells?
Local areas of ischaemia or necrosis
Whay does hypokalaemia do to phase 4 slope?
Increases it and also increases ectopics, prolongs repolarisation
What is the term for: in the terminal phase of AP (phase 3), a small depolarisation may occur (called an after depolarisation), and if of sufficient magnitute may reach threshold and lead to a sustained train of depolarisations
What mechanism underlyes digoxin toxicity, Torsades de Pointes in long QT syndrome and hypokalaemia?
What requires available circuit, unidirectional block, and different conduction speed in limbs of circuit?
Where is the origin in a ventricular arrhythmia?
What type of conditions promote functional block?
Conditions that depress conduction velocity or shorten refractory period promote functional block
What are four main investigations you would do for arrythmias?
1. 12 lead ECG
4. Stress ECG
What are signs on an ECG of a previous MI?
What does pre-excitation suggest, when seen on an ECG?
Wolf Parkinson White syndrome
What investigation can assess for ischaemia and excersise induced arrythmias?
What investigation is used to assess for paroxysmal arrythmia?
24hr Holter ECG
What investigation can assess for structural disease? (e.g. enlarged atria ain AF, LV dilatation or previous MI scar, aneurysm)
What study triggers arrythmia to study its mechanism and gives an opportunity to treat the arrythmia by radiofrequency ablation?
What condition can be asymptomatic, palpitations, there is generally no treatment, b-adrenergic blockers may help and you need to avoid stimulants like caffeine?
Atrial ectopic beats
What type of STEMI is bradycardia related ischaemia common in?
What are the two treatment options for sinus bradycardia?
1. Atropine (if acute)
2. Pacing if: haemodynamic compromise such as hypotension, CHF, angina or collapse
What drugs can be used to treat sinus tachycardia?
1. B-adrenergic blockers
16 year old girl, fast palpitations, alert, no distress, good colour, HR very fast and normal physical exam?
Narrow complex tachycardia, SVT
What three things may supra-ventricular tachycardia be due to?
1. AV nodal re-entrant tachycardia
2. Accessory pathway tachycardia i.e. Wolff Parkinson White syndrome
3. Ectopic atrial tachycardia
What would you do as initial emergency treatment for an infant with SVT?
Peds vagal maneovres
What emergency initial step would you do for a child with SVT?
Blow through straw or carotid massage
What emergency step would you do for an adult with AVT?
Carotid sinus massage
For management of supra-ventricular tachycardia, what would you give after you have performed vagal manoeuvres, carotid massage?
What 3 steps of chronic management for SVTs are there?
1. Avoid stimulants
2. Radiofrequency ablation
3. Antiarrythmic drugs (Class II or IV)
What is selective cautery of cardiac tissue to prevent tachycardia, targeting either an automatic focus or part of a re-entry circuit?
What three steps are involved in ablation?
1. Catheters placed in heart via femoral veins
2. Intracardiac ECG recorded during sinus rhythm, tachycardia and during pacing manoeuvres
3. Catheter placed over focus/pathway and tip heated to 55-65C
What investigation shows the activation sequence of the heart and has more detail than a surface ECG?
What type of arrythmic disease can ageing, acute MIs, myocarditis and infiltrative disease (amyloid) cause?
AVN conduction disease
What two classes of drugs cause AVN conduction disease?
Calcium channel blockers
What two genetic causes are there of AVN conduction disease?
Can calcific aortic valve disease and post-aortic valve surgery lead to AVN conduction disease?
In first degree AV block, what is the PR interval like?
Longer than >0.2 seconds
What is the treatment for first degree AV block?
What degree of block is an intermittent block at the AVN (dropped beats)?
2nd degree AV block
What are the two types of 2nd degree AV block?
Give two features of Mobitz type I 2nd degree AV block?
1. Progressive lengthening of the PR interval, eventually resulting in a dropped beat
2. Usually vagal in tone
Give three features of Mobitz II, 2nd degree AV block?
1. Pathological, may progress to complete heart block (3rd degree HB)
2. Usually 2:1, or 3:1, but may be variable
3. Permanent pacemaker indicated
In 2nd degree AV block, Mobitz II what do some action potentials fail to do?
Get through the AV node
What is the treatment for 2nd degree AV block Mobitz type II?
What can be said about hte action potentials in 3rd degree AV block?
No action potentials from the SA node/atria get through the AV node
What is the treatment for 3rd degree AV block?
What are two options for acute pacing?
1. Transcutaneous pacer
2. Transvenous pacer
What two types of pacemakers are there?
1. Single chamber (paces the right atria or right ventricle only)
2. Dual chamber (paces the RA and RV)
When are atrial pacemakers used?
In isolated SA node disease but normal AV node
When are ventricular pacemakers used?
In AF with slow ventricualr rate
What pacemakers maintain AV synchrony and are used for AVN dsiease?
What might premature ventricular ectopics be a marker for?
Inherited arrhythmia syndromes e.g. cardiomyopathy
What happens to the atrial pressure in ventricular tachycardia?
Large, sustained reduction
What two conditions do most patients have before getting ventricular tachycardia?
Coronary artery disease and previous MI
What are two inherited/familial arrhythmia syndromes that can cause ventricular tachycardia?
1. Long QT
2. Brugada syndrome
What can rates range from in ventricular tachycardia?
What are these ECG findings characteristic of: QRS complexes are rapid, wide and distorted, T waves are large with deflections opposite the QRS complexes, ventricular rhythm is usually regular, P waves are usually not visible, PR interval is not measurable, AV dissociation may be present, VA condution may or may not be present?
What arrythmia is chaotic ventricular electrical activity which causes the heart to lose the ability to function as a pump?
What are the two treatment methods for ventricular fibrillation?
What are two acute treatment options for VT?
1. DC cardioversion if unstable
2. If stable consider pharmacologic cardioversion with AAD
What do sotalol, quinidine, terfenadine and erythromycin do to the QT interval?
What are three causes of VT?
1. Hypokalaemia, hypomagnesaemia
For a monomorphic stable VT, what 4 drugs would you administer?
1. IV procainamide
2. IV sotalol
3. IV amiodarone
4. IV beta blockers
What can you implant if life threatening VT is there long term?
Implantable cardiovertor defibrillator (ICD)
What two arrythmias are life threatening?
VT and VF
What do most ventricular arrythmias occur in the setting of?
Structural heart disease
60 female, hypertension for years, palpitations, SOB, fatigue, on enalapril, irregularly irregular pulse?
Atrial fibrillation & LVH
What is the atrial activity like in AF?
Chaotic and disorganised
What three things can AF be defined as either?
Give two features of paroxysmal AF?
1. Paroxysmal and lasting less than 48 hours
2. Often recurrent
Give two features of persistent AF?
1. An episode of AF lasting greater than 48 hours, which can still be cardioverted to NSR
2. Unlikely to spontaneously revert to NSR
Give one feature of permanent AF?
Inability of pharmacological or non-pharmacologic methods to restore NSR
What are hypertension, congestive heart failure, sick sinus syndrome, coronary heart disease, thyroid disease, familial and valvular heart disease all causes of?
What are COPD, pneumonia, septicaemia, pericarditis and tumours all causes of?
What occurs in the absence of any heart disease and no evidence of ventricular dysfunction, a diagnosis of exclusion?
Give 5 symptoms of AF?
1. Palpitations and chest pain
2. Pre-syncope dizziness and syncope
Give two features of the mechanism of AF?
1. Multiple wavelets of reentry
2. Ectopic focus around the pulmonary veins
Give three terminations of AF?
1. Pharmacologic cardioversion with anti-arrythmic drugs
2. Electrical cardioversion
3. Spontaneous reversion to sinus rhythm
What three drugs can terminate and prevent AF?
What is the atrial rate and rythm of an ECG in AF?
1. Atrial rate > 300bpm
2. Rhythm: irregularly irregular
What three things is the ventricular rate on ECG in AF dependent upon?
1. AV node conduction properties
2. Sympahtetic and parasympathetic tone
3. Presence of drugs with act on the AV node
What is there the absence of P waves and the presence of "f" waves in?
What two classes of drugs decrease conduction in the AV node and are useful in controlling ventricular rate during AF?
Calcium channel blockers
For patients with hypertrophic cardiomyopathy, what can loss of atrial kick and decreased filling times result in?
Congestive heart failure
What can patients with pre-excitation (Wolff-Parkinson-White Syndrome) result in?
Ventricular fibrillation and sudden cardiac death
What in AF does lost 'atrial kick' and decreased filling times (reduced diastole) lead to?
Reduced cardiac output
What two approaches of management are there for AF?
Rhythm control - maintain SR predominantly
Rate control - accept AF but control ventricular rate
If there is a high risk for thromboembolism for both rhythm control and rate control, what should be done?
During rate control in AF, what 4 pharmacological therapies are there to slow down AVN conduction?
During rhythm control of AF, what two methods are there for restoring NSR?
1. Pharmacologic cardioversion (anti-arrythmic drugs e.g. amiodarone)
2. Direct current cardioversion (DCCV)
What three methods are there for rhythm control - maintainence of NSR in AF?
1. Anti-arrythmic drugs
2. Catheter ablation of atrial focus/pulmonary veins
3. Surgery (maze procedure)
What do flecainid, sotalol and amiodarone do to AF rythm?
Maintain sinus rhythm
During an episode of AF, what can immediatly restore normal sinus rhythm?
How do anti-arrythmic drugs act?
Through electrophysiological mechanisms by blocking the ionic currents across cell membranes that create the action potentials
What channel block, action potential phase and main use in AF are for Class I anti-arrythmic drugs?
Channel blocked: Na+
Action potential phase: 0
Main uses in AF: Rythm control
What class of anti-arrythmic drugs are flecainide and propafenone?
What are channels blocked, action potential phase and main uses in AF for class II anti-arrythmic drugs?
Channels blocked: beta-receptors
Action potential phase: 4
Main uses in AF: Rate control
What are channels blocked, action potential phase and main uses in AF for class III anti-arrythmic drugs?
Channels blocked: K+
Action potential phase: 3
Main uses in AF: Rhythm control
What are channels blocked, action potential phase and main uses in AF for class IV anti-arrythmic drugs?
Channels blocked: Ca2+
Action potential phase: 2
Main uses in AF: rate control
Name 4 class I anti-arrythmic drugs?
Give 1 class II anti-arrythmic drug?
Give three class III anti-arrythmic drugs?
Give one example of a class IV anti-arrythmic drug?
What is a rapid, distinct VT with a twisting configuration of the QRS morphology and associated with prolonged repolarisation?
Torsades de Pointes
What is the heart rate in Torsades de Pointes?
200 - 250bpm
What is the rhythm like in Torosades de Pointes?
Give three features for ECG recognation of Torsades de Pointes?
1. Long QT interval
2. Wide QRS
3. Continuously changing QRS morphology
Give three events leading to TdP?
2. Prolongation of the action potential duration (drug induced)
3. Renal impairment (increased drug levels)
What two valvular AF conditions would indicate for anti-coagulation?
What does CHA(2)DS(2)-VAS Score stand for?
Congestive heart failure/LV dysfunction - 1
Hypertension - 1
Age>75 - 2
Diabetes mellitus - 1
Stroke (TIA/TE) - 2
Vascular disease - 1
Age 65-74 years - 1
Sex - 1
What does HASBLED assess?
What does HASBLED stand for? (>3 is high risk)
Abnormal renal or liver function
Elderly > 65
Drugs or alcohol
How does radiofrequency ablation in AF maintain SR?
By ablating AF focus (usually in the pulmonary veins)
How does radiofrequency ablation in AF control rate?
Ablation of the AVN to stop fast conduction to the ventricles
Name a rapid and regular form of atrial tachycardia?
What is atrial flutter (paroxysmal) sustained by?
Where is the atrial flutter circuit combined to?
What does chronic atrial flutter usually progress to?
What is the rate usually in atrial flutter?
What is seen instead of a p-wave in atrial flutter?
Saw tooth 'F' wave
Is atrial flutter clockwise or counterclockwise?