Arrhythmia Flashcards
Broad complex tachycardia differential:
8 DIFFERENTIALS
SVT (any) with aberrancy
BBB morphology
Lack of VT features
AF with WPW
Irregular (may be subtle)
Rate >200
Na channel blockade
Terminal R wave aVR
HyperK
More typically brady
Accelerated IV rhythm
Differentiated on RATE- 50-120bpm
Patient stable
Typically post thrombolysis/ reperfusion
VT
Patient factors
ABDDEF+ on ECG
Rate >100/150
Variable patient state
polymorphic irregular, monomorphic reg
VF
Chaotic, no complexes
Rate 150-500
Patient arrested
Runaway PPM
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Clinically, main things are:
- IS THIS AF WITH WPW:
?irregular ?rate 200+
Avoid drugs, partic AV blockers
- IF IN DOUBT, SHOCK.
- If want to avoid DCR and SURE not WPW, adenosine may help differentiate.
In which lead are flutter waves best seen?
V1
Sick sinus syndrome:
Diseased SA node- typically surrounding fibrosis with old age.
ECG:
Sinus brady
Intermittent SA nodes failure (no P) –> sinus arrest (long pause) –> +/- escape rhythm/ tachy-brady –> resumption of sinus rhythm.
Can have collapse, instability
Mx:
Avoid antiarrythmics- all can make worse
- Atropine/ adren/ dobut/ isopren/ transcut as required
- PPM
5 causes of 1deg heart block:
PR= 3-5 sml (120 - 200ms)
Vagal tone
Drugs: CCB, BB, digoxin, amiodarone
Rarely, signifies a problem like ischaemia, myocarditis, valve disease.
No specific Tx required.
2deg heart block:
Mobitz I (Wenkebach)
Progressive lengthening
- Block AT the node. Mostly benign.
- Mx cause- avoid AV blockers etc.
- PPM if symptomatic only
Mobitz II
Regular drop
—> Not good. Structural damage BEYOND node.
–> High risk of deterioration to complete HB.
–> Admit, +- pace, PPM
Complete heart block:
Escape rhythm may be narrow (junctional) or wide (ventricular)
Unstable/ at risk sudden death
Trial atropine whilst setting up pacing (in case issue AT node)
Can trial Isoprenaline to enhance perfusingg escape rhythm
Pace, Urgent PPM
Management options in unstable bradycardia:
When vagally mediated:
- ATROPINE 20microg/kg, repeat Q10min
….OFTEN FAILS. Doesn’t work well when the SA or AV itself is dysfunctional (eg. heart block)
______
Next line (or if hypotensive +):
-
ADRENALINE 0.1microg/kg/min + titrate, max 20
Preferred in ISCHAEMIA- preserves coronary perfusion
OR
- DOBUMATINE 2.5 microg/kg/min + titrate, max 10
OR
-
ISOPRENALINE 0.5 - 2 microg/min + titrate, max 10
Contraindicated in digoxin
Only useful one in heart transplant
…Change to central access ASAP.
_________
- Transcutaneous pacing
- Transvenous pacing
- PPM
Bradycardia aetiology DDx:
‘Normal’
- Vagal (eg. vomit)
- Fit, young
Cardiac
- Heart block
- Ischaemia (incl inf AMI)
- Myocarditis
- Cardiomyopathy
- Fibrosis, infiltrative
Metabolic
- Hypothyroid
- Hypothermia
- Hypoglycaemia
- HypoMg
- Hypo/ hyper K
- Acidosis
- Hypoxia
Medication
- BB
- CCB
- Amiodarone
- Digoxin
- Na channel blockers *(TCA, amitrip/ nortrip)
- Clonidine
- Opioids
Toxicological
- Organophosphate
- Raised ICP/ Cushing’s
VAGAL predominance vs SYMPATHECTOMY vs ESCAPE RHYTHM ETC.
DDx narrow complex tachycardia:
REGULAR
- Sinus tachy
- SVT
- Flutter
- Junctional tachycardia
IRREGULAR
- AF
- SVT/ AF/ flutter with variable block
- MAT
- Dig toxicity
DDx broad complex tachycardia:
REGULAR
- VT (monomorphic)
- SVT with aberrancy
- Accelerated idioventric
- Na channel blockade
- Post-cardioversion
- HyperK (usually brady)
- Pacemaker tachycardia
IRREGULAR
- VF
- Polymorphic VT (incl. Torsades)
- AF with WPW
- AF with aberrancy
DDx narrow complex bradycardia
REGULAR
- Sinus brady
- Junctional
- 1st degree block
- Complete block
- Flutter with high degree block
IRREGULAR
- Sinus arrythmia
- Sinus pause/ arrests
- Slow AF
- Flutter with variable block
- Second degree heart block
DDx broad complex bradycardia
REGULAR
- Sinus brady with aberrhancy
- Idioventricular
- Ventricular escape
- Paced
- Hyperkalaemia
- Hypothermia
IRREGULAR
VT vs SVT with aberrancy:
IN SUPPORT OF VT:
Patient:
Age > 35 (PPV 85%)
Structural heart disease
IHD- active or past
FHX sudden cardiac death
ECG
ABCDEF+
A: Northwest/extreme axis (1 neg, aVf neg, aVr pos), Abscence of BBB
B: Broad >200ms
C: Concordance (+-, v1-6, no RS complexes), Capture beats
D: Dissociation (Ie. P waves)
E: Ear: LEFT rabbit ear V1 (as opposed to right in RBBB)
F: Fusion beats
+:
Josephson’s sign (notching of S wave nadir)
RS interval >100ms (‘Brugada Sign’) in a praecordial lead
If ANY of these present, 90-100% specific
What overall % of broad, regular tachy is VT?
70%
APPROACH to broad complex tachycardia:
Main question: Could this be AF with WPW
Avoid drugs- partic AV blockers.
–> If happens to be WPW, will precipitate VF.
If in doubt, shock.
Define non-sustained VT:
3 or more PVCs
but < 30 secs duration
Management of monomorphic VT:
1- AMIODARONE
5mg/kg IV stat –> 15mg/kg in 24-hour infusion
2- LIGNOCAINE
1mg/kg
Repeat 10 minutely up to 3x
–> 1-4mg/kg/hr infusion
3- SOTALOL
1mg/kg
- DCR 100 –> 150 –> 200J
- Overdrive pacing
- Optimise myocardial responsiveness (acidosis, hypoxia, temp)
________
STABLE:
–> Amiodarone
UNSTABLE: chest pain, ischaemia, syncope, hypoTN
–> 1- Synchronised DCR plus amiodarone
–> 2- Repeat DCR up to 3, second line agents (sotalol, ligno)
–> 3- Overdrive pace
PULSELESS:
–> ACLS
–> 3x unsynchronised stacked if monitored, witnessed
Management of Torsades (long QT PMVT):
Notoriously difficult to treat
1- UNSYNCHRONISED DCR if unstable
—> Lignocaine 1.5mg/kg is only safe antiarrhythmic (shortens QT)
2- MAGNESIUM
2g IV over 2 mins
–> 2g/hr infusion
(0.2mmol/kg kids)
Stop if Mg levels >=3mmol
3- Optimise QT
- Correct K, Ca
- Cease culprit meds
- Keep pulse rate >90
–> Isoprenaline
–> Overdrive pacing
_______
Pulseless: ACLS
Unstable: Unsynch DCR 200J
Stable: meds
What is Torsades?
Polymorphic VT in setting of QT prolongation
QT prolongation may be congenital, or acquired.
May be perfusing. But, can degenerate to RonT —> VF
Management is MAGNESIUM and OPTIMISE QT
(correct K, Ca, stop meds, increase PR- isoprenaline or pacing)
What 4 causes must be considered in the young person with VT? How can these be diagnosed?
1- Arrhythmogenic RV Dysplasia (ARVD)
- Fibrofatty deposits –> conduction disturbance
- Exertional
- VT with RVH and epsilon wave, RV strain
- Mx ablation
2- 1- Right Ventricular Outflow Tract VT (RVOT)
- Idiopathic
- Exertional or random
- VT with LBBB
- Mx as per SVT
3- Catecholaminergic polymorphic VT
- Dx in childhood
- Exertion, emotion or stress
- *Mx Beta blockers
4- Congenital long QT with Torsades