Arrhythmias Flashcards
What is an SVT?
Narrow complex tachyarrhythmia
Abnormally fast HR arising from atrium
What are the main types of SVT?
AF
Paroxysmal SVT
Atrial flutter
WPW Syndrome
What are the risk factors for an SVT?
Prev SVT Structural abnormality Alcohol ↑T4 Caffeine
What are the signs of someone in SVT?
Palpitations SOB Dizziness Tachycardia Anxiety
What is seen on an ECG of SVT?
Narrow QRS complexTachycardia >140
WITH P waves (may merge into QRS)
WITHOUT P waves = AF
How is SVT managed?
Conservative for REGULAR SVT: Vagal manoeuvres/ carotid massage 10s per side
Chemical for REGULAR SVT: Adenosine 6mg IV rapid - flush w/20ml saline, repeat w/12mg x2
Definitive: Pathway ablation
What is WPW Syndrome?
Re-entrant tachycardia from accessory conduction pathway between Atria & ventricles
BUNDLE OF KENT
What does an ECG of someone with WPW syndrome look like?
Tachycardia
Wide QRS
Short PR
Delta waves in V1
How is WPW Syndrome treated?
REFER to cardiology
1) Flecanide/amiodarone
2) Accessory pathway ablation
What medications are best avoided in WPW Syndrome? Why?
Beta Blockers
CCB
Adenosine
Can precipitate VT/VF
What is AVNRT?
1st beat fast conduction
New beat goes through slow conduction
Causes retrograde re-entrant conduction
Tx: As narrow complex tachycardia
What is the mechanism behind AF?
Disorganised electrical impulses AV node responds intermittently Atrial spasm Abnormal ventricular rate Ineffectively primed ventricles ↓CO
What are the causes of AF?
PIRATES: P: PE I: IHD & HF (MOST COMMON), MI R: Resp disease A: Atrial enlargement (MV disease) or myxoma, T: Thyroid disease (hyper) E: Ethanol (“Holiday heart” after binging), caffeine S: Sepsis or Sleep apnoea
What are the different types of AF?
Acute: Onset <48hours
Recurrent: >2 episodes
Paroxysmal: AF resolves spontaneously in 7d
Persistent: >2 episodes, not self-limiting, requires cardioversion
Permanent: >1yr cannot resolve w/cardioversion
How is AF investigated?
ECG: Irregularly irregular R-R intervals, absent P waves,
Bloods: TFTs, U&E, LFT, FBC, HbA1c
ECHO: LA enlargement, mitral valve disease
How is acute AF managed?
<48 hours!!
1) Cardioversion
Electrical: DC 120J shock under sedation
Chemical: Flecainide/ Amiodarone
What 2 groups of patients with stable AF are at risk of becoming unstable?
1) Patients with poor LV function
2) Whose where AF results very high HR (>150) leading to inadequate LV filling + ↓CO
What do the different CHADs-VASC scores correlate to in terms of treatment?
OFFER anticoagulant to ALL scoring >2
CONSIDER anticoagulant to MEN scoring 1
1) NOAC 2) Warfarin 3) Aspirin
What HAS-BLED score would indicate no anticoagulation?
> 2
When should Flecainide/ Amiodarone be used/ not used in chemical cardioversion?
F: If NO structural abnormalities & no ischaemia
A: If Are structural abnormalities
How is AF presenting >48hours managed?
1) RATE Control: Beta-Blocker/ CCB
2) RHYTHM Control: Persistent AF- anticoagulate for 3w + Amiodarone for 4w before
THEN DC Cardioversion + Amiodarone for 12m after + anticoagulation 4w afterwards
According to NICE who does not need to be rate controlled?
- AF with reversible cause
- HF primarily caused by AF
- New onset AF (<48hrs)
- Rhythm control strategy would be more suitable
What surgery can be offered to someone in AF?
LA ablation (rhythm control) if drugs failed LA appendage occlusion
If someone presents with AF + abdominal pain what diagnosis should be considered?
Mesenteric ischaemia!
What are the signs of Digoxin toxicity?
N&V&D Blurred/ yellow vision Confusion HypoK exacerbates Sx ECG: Prolonged PR, inverted T waves, ST depression, U waves
What is atrial flutter?
Re-entrant rhythm in L or R atrium causing an endless loop by over-riding SA node
Contracts at >300bpm
What are the types of atrial flutter?
T1: Typical, 240-350 bpm, single circuit around tricuspid valve, counter clockwise
T2: Atypical, >350 bpm, location less defined
What are the risk factors for atrial flutter?
Male ↑age CAD Valve dysfunction HTN Obesity OH- COPD Obstructive sleep apnoea Thyrotoxicosis
How is atrial flutter investigated?
ECG- GOLD STANDARD
Bloods: TFT, FBC, ESR, U&E, LFT, Coag
CXR: Signs of HF
ECHO
How is acute unstable atrial flutter managed?
HF/Syncope/MI/Shock
DC Shock x3 → Amiodarone 300mg IV → Shock → Amiodarone 900mg
How is acute stable atrial flutter managed?
Vagal manoeuvres
Adenosine 6mg Iv → 12mg x2
Rate control: BB/ CCB
How is atrial flutter for >48hours treated?
1) Catheter ablation
2) Anticoagulate + Amiodarone (4 wks) → DC shock → Anticoagulate (4wks)
3) Rate control
4) Pacemaker
What is the mechanism of VT?
Ventricular ectopic focus →
Ventricular pacemaker cells overtake rate of SA node →
Broad complex tachycardia w/ ≥ 3 premature ventricular contractions in succession at rate > 120bpm
What are the 2 types of VT?
Monomorphic: COMMON, Regular rhythm originating from single focus with IDENTICAL QRS complexes
Polymorphic: Irregular rhythm, VARIATION in QRS complexes
What are the risk factors for VT?
IHD Trauma Hypoxia Acidosis Long QT HypoK/Ca/Mg
How does VT present?
Palpitations Dizziness SOB/ Resp distress Tachycardia Pallor !!! = HypoT, HF, MI, Syncope, Pulseless, Chest pain
How is VT investigated?
ECG: Regular tachycardia, Broad QRS, absent P waves
Bloods: U&E!!, Ionised Ca2+, PO4-, Troponin
How is VT managed?
Oxygen IV Access 1) Amiodarone 300mg IV over 20-60mins THEN 900mg IV over 24hrs Replenish electrolytes Implantable cardioverter defibrillator
How is pulseless VT or VF treated?
Unsynchronised Defibrillation
CPR
Which patients with VT are eligible for a implantable defibrillator?
Sustained VT causing:
Syncope OR EF <35%
Prev cardiac arrest due to VT/VF
MI
What are the complications of VT?
VF often proceeds!
Torsades de pointes (Tx IV Mg)
Congestive HF → ↓preload, due to fast ventricular rate → ↓blood flow to vital organs
Cardiogenic Shock
What is VF?
MEDICAL EMERGENCY
Ventricle muscle fibres fibrillate in uncoordinated, unsynchronised manner → insufficient blood pumping around body → cardiac arrest + sudden cardiac death
Which rhythms are shockable and which are not?
YES = VF & VT NO = PEA & Asystole
What are the risk factors for VF?
IHD/CAD MI Hypoxia AF Electric shock during cardioversion Long QT WPW Syndrome Electrolyte imbalance
How does VF present?
INITIAL: Chest pain, palpitations, fatigue
THEN: Sudden loss of responsiveness, ABSENT breathing & pulse
How is VF investigated?
ECG: 500bpm, no P/QRS/T waves
Bloods: CK, Trop, U&E, TFT
How is VF managed?
ALS:
CPR 30:2 (continuous compressions when advanced airway support)
1st SHOCK: Stand clear, remove O2, defibrillator to 150J
CPR for 2 mins
2nd SHOCK
CPR for 2mins
3rd SHOCK
CPR for 2mins
ADRENALINE 1mg IV 10ml 1:10000
AMIODARONE 300mg IV
Give Adrenaline after every alternate shock (5th, 7th, 9th..)
What are the reversible causes of cardiac arrest?
4 H’s + 4 T’s
- Hypothermia
- Hypoxia
- Hyper/hypokalaemia
- Hypovolaemia
- Toxins
- Tamponade
- Tension PT
- Thrombus (coronary/pulmonary)
How is refractory VF managed?
Consider Vasopressin: 40u bolus ADH
Output restored: Amiodarone 300mg IV → 900mg 24/h infusion
