Arrhythmia Flashcards
Cardiac causes [6]
Ischemic heart disease
Structural changes
Cardiomyopathy
Pericarditis
Myocarditis
Aberrant conduction pathways (WPW syndrome)
Non cardiac causes [5]
Electrolyte imbalance
Metabolic - hypoxia/acidosis/thyroid
Caffeine, Smoking, Alcohol
Pneumonia, phaeochromocytoma
Drugs
Drugs that cause arrhythmia [5]
Levodopa
Digoxin
Beta 2 agonists (asthma drugs)
Tricyclic antidepressants
Doxorubicin
Presentation [7]
Palpitations
Dyspnoea
Chest pain
Fatigue
syncope/presyncope
Pulmonary oedema
Can be asymptomatic
Initial mx of arrhythmias [6]
ABCDE
Oxygen
Gain IV access
12 lead ECG
Correct metabolic abnormalities
Classify patient as stable or unstable
What is a sinus arrhythmia? [3]
Management?
Normal conduction at faster frequency
HR increases inspiration
Decreases expiration
No Rx needed
Causes of sinus arrhythmia [7]
Infection, fever
dehydration, hypovolaemia
pain / exercise
drugs, salbutamol
adrenaline
PE
hypothyroid
MI
Categorisation of tachyarrhythmias
Supraventricular - narrow complex
Ventricular - broad complex
Sinus tachycardia
Features suggesting VT rather than SVT with aberrant conduction
AV dissociation
fusion or capture beats
positive QRS concordance in chest leads
marked left axis deviation
history of IHD
lack of response to adenosine or carotid sinus massage
QRS > 160 ms
What is a narrow complex tachycardia and why? [4]
> 100BPM
QRS <120
Short P wave
Ventricles depolarised via normal pathway so QRS normal
Types of regular narrow complex tachycardias [5]
Regular
* Sinus tachycardia
* Atrial tachycardia (unifocal)
* Atrial flutter
* AV re-entry tachycardia (WPW pattern)
* AV nodal re-entrant tachycardia (AVNRT)
Multifocal atrial tachycardia
Definition? Demographic it is more common in
Multifocal atrial tachycardia (MAT) may be defined as a irregular cardiac rhythm caused by at least three different sites in the atria, which may be demonstrated by morphologically distinctive P waves. It is more common in elderly patients with chronic lung disease, for example COPD
How is multifocal atrial tachycardia managed?
correction of hypoxia and electrolyte disturbances
rate-limiting calcium channel blockers are often used first-line
cardioversion and digoxin are not useful in the management of MAT
What is WPW [2]
ECG [2]
AV re-entrant tachycardia - another pathway through atrial and ventricle not AV node
Complications: AF, VF
ECG:
- short PR interval
- wide QRS complexes with a slurred upstroke - ‘delta wave’
What causes irregular narrow complex [3]
Irregular NCT
* AF
* Atrial flutter with irregular block
* Multifocal atrial tachycardia
What is associated with WPW [4]
HOCM
Mitral valve prolapse
Ebstein
Thyrotoxicosis
APs can be left-sided or right-sided, and ECG features will vary depending on this:
Describe ECG features in Type A vs Type B
Left-sided AP: produces a positive delta wave in all precordial leads, with R/S > 1 in V1. Sometimes referred to as a type A WPW pattern
Right-sided AP: produces a negative delta wave in leads V1 and V2. Sometimes referred to as a type B WPW pattern
Localisation of the aberrant accessory pathway in AVRT
The closer the accesory pathway is to the sinoatrial node or site of atrial ectopy, the greater the degree of pre-excitation.
Pathway originating from right free wall
* shortened PR interval
* broader QRS
Pathway originating from left free wall
* more normal ECG
Orthodromic vs Antidromic AVRT
Orthodromic
* Atrial ectopic beat is propagated in usual anterograde fashion, then retrograde conduction occurs along aberrant accessory pathway.
Antidromic
* If ventricular ectopic is propagated in a retrograde fashion via myocardial cells not usual conduction system, this results in a boarder QRS - this may resemble VT.
Management of AVRT and AVNRT are similar
AVNRT
* Paroxysmal AVNRT - transient AV node blockade using verapamil, BB, verapamil. These induce block along slow pathway.
* Infrequent symptoms but clear onset, prescribe PRN flecainide.
* Definitive mx includes catheter ablation of the slow pathway.
Pathophysiology in AVNRT
AV NODAL re-entry
* Congenital abnormality where AVN has dual physiology - fast and slow circuits.
* Premature atrial complex occurs when fast pathway is in refractory mode > so the electricity is conducted on slow pathway. Once the electricity goes along two pathways this creates a re-entry circuit.
Remember the major difference in AVRT vs AVNRT is
AVRT = WPW and is caused by a congenital ‘aberrant’ accessory pathway connecting atria and ventricles, NOT through the AV node.
In narrow complex tachycardias, what can you use instead of adenosine if contraindicated?
Adenosine is contraindicated in asthma
Another option is to use verapamil which slows AV nodal conduction
Management of supraventricular tachycardias
Acute management
1. vagal manoeuvres:
Valsalva manoeuvre: e.g. trying to blow into an empty plastic syringe
carotid sinus massage
2. intravenous adenosine
rapid IV bolus of 6mg → if unsuccessful give 12 mg → if unsuccessful give further 18 mg
3. electrical cardioversion
Prevention of episodes
* beta-blockers
* radio-frequency ablation
What is the Valsalva manoeuvre [5]
Forced expiration against closed glottis Increases intrathoracic pressure Reduced venous return due to increased atrial pressure Reduced preload Reduced CO
Atrial flutter [4]
- characterised by a succession of rapid atrial depolarisation waves.
- ECG: sawtooth appearance
- as the underlying atrial rate is often around 300/min
- the ventricular or heart rate is dependent on the degree of AV block.
For example if there is 2:1 block the ventricular rate will be 150/min
Atrial flutter management [2]
- cardioversion
- radiofrequency ablation of the tricuspid valve isthmus is curative for most patients
Atrial fibrillation pathophysiology [3]
Types [3]
- SA node isn’t firing properly = disorganised signal
- Other sites as well as SA node initiate conduction
- CO drops as ventricles not primed reliably leading to HF / increased risk of stroke
Paroxysmal - <7 days and self terminate
Persistent
Permanent - resistant to Rx
What are cardiac causes of AF: valvular [1] and non-valvular [9]
Valvular = MS / prosthetic heart valve issue
Non-valvular
* Ischaemia = most common UK
* Rheumatic = common world wide
* HF
* Hypertension
* IHD
* Cardiomyopathy
* Myocarditis
* Endocarditis
* Surgery
What are non-cardiac causes [8]
Sepsis PE, Bleed Pneumonia Hyperthyroid Alcohol, Caffiene, Drugs Post op Metabolic: Low K / Mg / Ca, Acidosis
Most common causes of AF (SMITH)
SMITH
Sepsis
Mitral valve - S or R
IHD
Thyrotoxicosis
Hypertension
Aetiology Bradycardia
split into extrinsic or intrinsic
Intrinsic
* Idiopathic degeneration - ageing
* Infiltrative disease - sarcoidosis, amyloidosis
* Infectious - endocarditis
* Autoimmune - SLE, RA, scleroderma
* Trauma - valve replacement
Extrinsic
* Increased vagal tone from Vasovagal syncope ir exercise training
* Electrolyte imbalancce - hypo/hyperkaelemia, hyponatremia
* Metabolic - hypothyroidism, hypothermia
* Neurological - raised ICP
What is the complication in WPW and management principles
Patient has AF
1:1 conduction > VF > SCD
So this affects clinical management because blocking AV node will encourage conduction along aberrant pathway.
PRN flecainide can be an option in infrequent episodes with no LV dysfunction, no IHD.
Definitive treatment
Catheter ablation
Management of peri-arrest bradycardia
◆ IV atropine ± isoprenaline if symptomatic.
◆ Treat reversible causes (e.g. metabolic abnormality or stop offending drug).
◆ Consider pacemaker insertion.
Indications for pacing [7]
- Sinus node disease
- Acquired AV Block
- Congenital AV block
- Neurocardiogenic syncope
- Overdrive pacing for atrial tachyarrhythmias
- Left ventricular outflow tract obstruction in HOCM
*–Right ventricular apical pacing with short AV delay reduces LVOT gradient and symptoms in a subset of HOCM patients - Acquired long QT syndrome e.g., amiodarone overdose
What is considered persistent or permanent atrial fibrillation
persistent (>7 days, but ‘cardiovertable’) or permanent (>7 days + NSR not
possible).
Annual stroke risk
CHA2DS2VASC score
Remember that if a CHA2DS2-VASc score suggests no need for anticoagulation it is important to ensure a transthoracic echocardiogram has been done to exclude valvular heart disease, which in combination with AF is an absolute indication for anticoagulation.
Same risk for paroxysmal vs persistent
Apixaban 5mg BD lifelong
May be used in conjunction with the CHA₂DS₂-Vasc Score to risk stratify patients for clinically significant bleeding to help guide decisions on anticoagulation in patients with atrial fibrillation.
ORBIT score
- Age >74 +1
- Bleeding history - any history of GI bleed, intracranial bleeding/ haemorrhagic stroke +2
- GFR<60 +1
- Treatment with antiplatelet agents
Management of atrial fibrillation, what factors do you have to consider?
- Age: elderly > rate control. Young symptomatic patients, consider rhythm control
- If young patient and adverse featurse > DC cardioversion
- Onset of symptoms >48h: delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks (if considered for long term rhythm control). If elderly then just rate control
What is sinus arrest? [2]
Management [2]
SA node fails to generate an impulse
No pulse
Mx:
CPR pathway
Adrenaline
Palpitations
24 hour ECG or event recorder electrocardiogram?
Those who have episodes less than 24 hours apart should have a 24-hour ambulatory electrocardiogram. In patients who experience episodes more than 24 hours apart, an event recorder electrocardiogram would be the most suitable investigation of choice.
Long QT syndromes
an inherited condition associated with delayed repolarization of the ventricles. It is important to recognise as it may lead to ventricular tachycardia/torsade de pointes and can therefore cause collapse/sudden death.
Long QT1 - usually associated with exertional syncope, often swimming
Long QT2 - often associated with syncope occurring following emotional stress, exercise or auditory stimuli
Long QT3 - events often occur at night or at rest
2 Congenital causes of Long QT
Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel)
Romano-Ward syndrome (no deafness)
Drugs that cause long QT
amiodarone, sotalol, class 1a antiarrhythmic drugs
tricyclic antidepressants, selective serotonin reuptake inhibitors (especially citalopram)
methadone
chloroquine
terfenadine
erythromycin
haloperidol
ondanestron
