Tachyarrhythmias Flashcards
What is the definition of a narrow complex tachycardia?
Heart rate > 100bpm and a QRS less than 120ms
What are some examples of REGULAR narrow complex tachycardia?
- Sinus tachycardia
- focal atrial tachycardia
- Atrial flutter,
- Atrioventricular re-entry tachycardia (occurs when there is an accessory pathway - WPW)
- Atrioventricular nodal re-entry tachycardia - SVT
- Junctional tachycardia
What are some causes of IRREGULAR narrow complex tachycardia?
- Atrial fibrillation - irregularly irregular rhythm with no P waves.
- Atrial flutter with variable block
- Multifocal atrial tachycardia (COPD)
What are the symptoms and signs of narrow complex tachycardia?
Symptoms: Palpitations, lightheadedness, dyspnoea, chest pain, syncope
Signs - tachycardia. Hemodynamic instability (shock, chest pain, heart failure or syncope)
What are the investigations for a narrow complex tachycardia?
- ECG,
- 24 hour tape is rhythm is paroxysmal
- Bloods (electrolytes)
- Imaging (ECHO)
What is the management of a regular narrow complex tachycardia?
- A-E exam. If signs of hemodynamic instability then synchronized DC cardioversion +/- amiodarone
- 1st line = Vagal maneuvers (valsalva or carotid sinus massage)
- 2nd line = Rapid bolus of adenosine (verapamil is asthmatic). Start with 6mg, if unsuccessful then 12mg, if unsuccessful then 18mg.
- 3rd line is electrical cardioversion
How can you prevent episodes of SVT?
Beta blockers or radiofrequency ablation
What is the management of acute irregular narrow complex tachycardia?
- If probable AF then beta blockers (not in the context of sepsis)
- If signs of heart failure then digoxin
- If onset was >48 hours then anticoagulation
What are the types of atrial fibrillation?
- Paroxysmal AF (episodes usually last less than 24 hours but must last than 7 days)
- Persistent AF (Lasts more than 7 days and doesn’t terminate)
- Permanent AF (cannot be cardioverted)
What is the principles of managing AF?
- Rate control (most common) of rhythm control
- Stroke prevention
- Catheter ablation in area between pulmonary veins and left atrium. (in those whose AF has not responded to antiarrhythmic meds
What are the causes of AF?
- Ischaemic heart disease,
Hypertension,
Symptomatic heart failure,
Valvular heart disease,
Cardiomyopathies,
ASD/other congenital heart disease,
Coronary artery disease,
Thyroid dysfunction,
Obesity,
Diabetes mellitus,
COPD and sleep apnoea,
Chronic renal disease - Non cardiac causes: dehydration, hyperthyroidism, sepsis, pneumonia/PE, alcohol abuse, hypokalaemia or hypomagnesaemia
When should rhythm control be offered for AF?
- AF secondary to a reversible cause,
- Heart failure thought to be caused by AF,
- New onset AF
- Younger patients
- Symptomatic patients despite good rate control
Describe features of rate control for AF
- First line - Beta blocker (bisoprolol) or rate limiting calcium channel blocker (contra-indicated in heart failure).
- If hypotension or heart failure then use Digoxin as first line
- Second line = Combination of 2 of following: beta-blocker, or digoxin
- Aim for HR <110 but if still symptomatic then aim <80bpm
Describe features of rhythm control
- Can only be done if onset is less than 48h or they have been anti-coagulated for >3 weeks. Can be done via meds or DC cardioversion.
Meds: Flecanide (pill in pocket or given regularly. Fatal in those with structural heart disease). Amiodarone (for older, sedentary patients). Sotalol (for those who dont meet demographics for flecanide or amiodarone)
Explain the CHA2DS2VASc score
C - congestive HF,
H - Hypertension
A2 - Age > 75
D - diabetes,
S2 - Prior stroke, TIA or thromboembolism
V - vascular disease
A - Age 65-74
S - Female sex
Offer anticoagulation if men score 1+ and women score 2+
What is the anticoagulation for AF?
- DOAC (first line)
- Warfarin: requires cover with LMWH for 5 days when initiating as warfarin is initially prothrombotic. Used for valvular AH
What scoring system is used to assess risk of bleeding?
ORBIT score: Sex, Hb, Age >74, bleeding history, renal function and use of antiplatelets
When should you start anticoagulation in AF patients post stroke?
- If they had a TIA then start anticoagulation as soon as haemorrhage is excluded.
- In stroke patients anticoagulation should start 2 weeks after stroke. Antiplatelet should be given during this time period.
What are the complications of atrial fibrillation?
- Heart failure
- Systemic emboli
- Bleeding
What are the causes of atrial flutter?
Similar to AF but more likely to occur with pulmonary disease such as COPD, obstructive sleep apnoea, pulmonary emboli or pulmonary hypertension
What is the treatment for atrial flutter
If haemodynamically unstable - Cardioversion
If haemodynamically stable then treat reversible cause and rate control using BB or CCB
Name examples of broad complex tachycardia
- Monomorphic ventricular tachycardia: Most commonly caused by MI.
- Polyphorphic VT, eg, torsades de pointes which is caused by prolongation of the QT interval.
what are some causes of QT prolongation?
Congenital: Jervell-Lange-Nielsen syndrome, Romano-Ward syndrome
Drugs: Amiodarone, Tricyclic antidepressants, fluoxitine, cloroquine, erythromycin, quinolones.
Other: Hypokalaemia, hypocalaemia, hypomagnesaemia, acute MI, myocarditis, hypothermia, SAH
What are the ECG findings of VT?
- Tachycardia
- Abscent P waves,
- broad QRS >120ms
What is the management of VT?
Pulseless - 200J unsynchronised shock, IC adrenaline and IV amiodarone administered after 3rd shock. Then Adrenaline every 3-5mins.
Pulsed VT with haemodynamic instability - Synchronised DC shocks and senior guided amiodarone
Pulsed VT with haemodynamic stability - Amiodarone 300mg over 10-60mins, if ineffective then DC shocks
Never use verapamil!!
What are features of ventricular fibrillation and ECG findings
- VF is an irregular broad complex tachy. It is ALWAYS pulseless.
- ECG: Tachycardia, QRS complexes which are polymorphic and irregular
What is the management of VF?
- 200J biphasic unsynchronised shock
- IV adrenaline (1mg of 10ml 1:10,000) and IV amiodarone (300mg) after 3rd shock.
- Adrenaline every 3-5mins thereafter
What is the management of torsades de pointes
IV magnesium sulphate
