Palpatations Flashcards
Name the five phases of an action potential.
Phase 0 - rapid depolarisation
Phase 1 - early depolarisation
Phase 2 - plateau phase
Phase 3 - repolarisation
Phase 4 - resting membrane potential
Describe which channels are open/closed in each phase of a ventricular action potential.
Phase 0 - Na+ channels open
Phase 1 - Na+ channels close. K+ channels begin to open.
Phase 2 - Ca2+ channels open
Phase 3 - slow delayed-rectifier K+ channels open. Ca2+ channels close.
What is the most common cause of broad complex tachycardia?
Ventricular fibrillation.
What are the four main differentials for a narrow complex tachycardia?
Sinus tachycardia
Supraventricular tachycardia (SVT)
Atrial fibrillation
Atrial flutter
How can you distinguish supraventricular tachycardia from atrial fibrillation on an ECG?
Both will have narrow complex tachycardia, but in supraventricular tachycardia the QRS complexes will be regular, whilst in atrial fibrillation, they will be irregularly irregular.
What examination findings may indicate thyrotoxicosis? (3)
Goitre
Tremor
Exophthalmos (bulging of the eyes)
What are the three common descriptions of palpations?
Flip-flopping in chest
Rapid fluttering in chest
Pounding in neck
What are the indicated aetiologies for each of the common descriptions of palpations?
Flip-flopping in chest —> extra systoles (such as supraventricular or ventricular premature contractions)
Rapid fluttering in chest —> sustained ventricular or supraventricular arrhythmia (sudden cessation of this sensation can suggest paroxysmal SVT)
Pounding in neck —> if irregular, can indicate atrioventricular dissociation (atria contracting against closed AV valves produces cannon A waves)
What pathologies can palpitations induced by exercise be suggestive of? (3)
Cardiomyopathy
Ischaemia
Channelopathies
What are the three categories of palpitation causes?
High output states
Structural cardiac causes
Catecholamine excess
Describe the pathophysiology of a bradycardic arrhythmia.
Depolarisation fails to initiate or conduct properly, such as in
SA node disease or heart block.
Describe the pathophysiology of a tachycardic arrhythmia.
There is abnormal depolarisation occurring in the heart, such as in enhanced automaticity or reentry.
Name the three types of SA node disease.
Sinus bradycardia
Sinus pause
Sinoatrial exit block (heart block)
What is sinus pause?
A condition where the SA node fails to generate an electrical impulse for what is generally a brief period of time.
What is sinoatrial exit block?
A condition where the depolarizations that occur in the sinus node cannot leave the node towards the atria; they are blocked.
Describe the four types of heart block.
1st degree - slow conduction through AV node
2nd degree (Wenckebach or Mobitz Type I) - AV conduction becomes slower and slower until it misses a beat
2nd degree (Mobitz Type II) - fixed block (usually 2:1)
3rd degree - complete heart block; there is no conduction to the ventricles and an escape pacemaker takes over from the His-bundle / bundle branch
What is automaticity?
A condition where an area of myocardial cells depolarise faster than the SA node. This may be atrial or ventricular tissue; most occur at a single ‘focal’ site.
What is reentry?
Where there is an electrical pathway that is not supposed to be there, connecting two areas that should not be connected and forming an abnormal electrical circuit.
What is supraventricular tachycardia (SVT)?
A heart condition where the heart suddenly beats much faster than normal; originates from faulty electrical impulses in the upper part of the heart, rather than from the ventricles.
What is ventricular tachycardia (VT)?
A sequence of three or more ventricular beats; the frequency must by higher than 100 bpm, mostly it is 110-250 bpm.
Name the five different types of supraventricular tachycardia (SVT).
Atrial fibrillation
Atrial flutter
AV nodal reentrant tachycardia (AVNRT)
Atrial tachycardia
Atrio-Ventricular Reentry Tachycardia (AVRT)
Which type of SVT is grossly irregular?
Atrial fibrillation
What are the two types of ventricular arrythmia?
Ventricular tachycardia
Ventricular fibrillation
Which type of ventricular arrythmia is irregular?
Ventricular fibrillation
What is Wolff-Parkinson-White (WPW) Syndrome?
A supraventricular tachycardia (SVT) that uses an atrioventricular (AV) accessory tract; the accessory pathway may also allow conduction during other supraventricular arrhythmias, such as atrial fibrillation or flutter.
What are the two types of Wolff-Parkinson-White (WPW) Syndrome classified based off of ECG results?
Type A: delta wave and QRS complex are predominantly upright in the precordial leads. (May be mistaken for RBBB.)
Type B: delta wave and QRS complex are predominantly negative in leads V1 and V2 and positive in the other precordial leads (may be mistaken for LBBB).
What are vagal manoeuvres?
Physical actions that stimulate your vagus nerve to act on the heart’s natural pacemaker, slowing down the electrical impulses there.
What are the diagnostic indications for use of vagal manoeuvres? (2)
-Valsalva manoeuvre can be used to distinguish between ventricular tachycardia and supraventricular tachycardia by slowing the rate of conduction at the SA or AV nodes.
-Carotid sinus massage can be used to diagnose carotid sinus hypersensitivity.
What are the therapeutic indications for use of vagal manoeuvres?
They are first-line treatment of hemodynamically stable supraventricular tachycardia, serving to slow down or terminate the arrhythmia.
How do you perform the valsalva manoeuvre?
While lying on your back, take a deep breath and act like you’re exhaling but with your nose and mouth closed for 10 to 30 seconds. It should feel like trying to breathe air out into a blocked straw.
When is it unsafe to perform vagal manoeuvres?
When the patient is haemodynamically unstable - they may have low BP, chest pain, SOB, oxygen deficit or perfusion deficit.
What is ectopy (in a cardiology context)?
One of the commonest causes of palpitations - the origination of cardiac electrical impulses in the myocardium outside of the sinoatrial (SA) node.
What is the only way atrial fibrillation can be confirmed?
An ECG demonstrating an irregularly irregular R-R interval and absent or abnormal p waves for more than 30 seconds.
What features should you ask about when taking a palpitations history? (11)
-Nature
-Rate
-Regularity (“can you tap out the rhythm?”)
-Duration
-Onset/offset
-Frequency
-Associated symptoms
-Red flags (syncope!)
-PMH of structural heart disease
-FMH of sudden cardiac/premature death
-Drug and medication history
Why is there usually a degree of AV block during atrial fibrillation?
The atrioventricular (AV) node is usually unable to conduct at the rapid rates of disorganised depolarisation occurring in the atria. This makes ventricular conduction random and irregular.
What is the difference between paroxysmal and persistent atrial fibrillation (AF)?
Paroxysmal AF lasts between 30 seconds and 1 week, whilst persistent AF lasts over 1 week.
What are three potential major adverse consequences of atrial fibrillation (AF)?
Stroke
Heart failure
Anxiety/depression
What is the HASBLED score?
A useful means of identifying risk factors associated with a high bleeding risk - patients with a HASBLED score of 3 or more are deemed high risk and require close monitoring.
Which DOAC is licensed for use in patients with Chronic Kidney Disease (CKD)?
Apixaban
Give four available treatment options for atrial fibrillation (AF).
-Medications for rate control (i.e beta blockers)
-Medications to maintain sinus rhythm
-Catheter ablation to maintain sinus rhythm
-Permanent pacemaker to allow use of medications +/- an AV node ablation (i.e., pace and ablate)
What should patients with mechanical heart valves or moderate to severe rheumatic mitral stenosis be offered for anticoagulation instead of DOACs?
Warfarin
What is the aim for heart rate control in atrial fibrillation (AF) patients?
An average HR<100 bpm or <110 bpm in older patients over 70 years.
What are the four rate control treatments available for atrial fibrillation (AF), in order of first-line to ‘last resort’?
Beta blockers (1st line)
Calcium channel blockers (2nd line)
Digoxin (can be added as adjunct if rate poorly controlled despite first line or second line)
Permanent pacemaker
What are the six types of rhythm control available for treatment of atrial fibrillation (AF)?
Flecainide
Sotalol
Amiodarone
Dronedarone
Catheter ablation
DC cardioversion
When should calcium channel blockers for atrial fibrillation (AF) be avoided?
In patients with left ventricular systolic dysfunction.
What is flecainide?
A cardiac sodium channel blocker - the most commonly used antiarrhythmic drug for AF in the UK.
When should flecainide be avoided?
In patients with coronary artery disease and structural heart disease.
What needs to be monitored in patients taking sotalol or amiodarone?
QTc interval should be measured prior to starting and after any dose adjustments, because sotalol can cause QTc prolongation.
Which rhythm control treatment available for atrial fibrillation (AF) can be given to patients with structural heart disease?
Amiodarone
