Arrhythmias
Syncope
Ix
ECG to diagnose
ECHO to exclude cardiac tumour
Sinus rhythm: p before every qrs, qrs after every p
Sinus arrhythmia: HR increases with inspiration
Junctional rhythm: narrow complex
Heart block (AV node dysfunction)
SVT
Ventricular tachyarrhythmias
Long QT
K
Antiarrhythmics
Ix
ECG to diagnose
ECHO to exclude cardiac tumour
Sinus rhythm: p before every qrs, qrs after every p
Sinus arrhythmia: HR increases with inspiration
Junctional rhythm: narrow complex
- J. escape rhythm (AV node paces in sinus node dysfunction) HR 40-60
- Accelerated Junctional rhythm (AV node paces but faster) HR 60-100 ?drugs
Heart block (AV node dysfunction)
- 1st Degree: ALL conducted but prolonged PR
- 2nd Degree: Intermittant conduction, can have pattern of 2:1, 3:1 (p:q) but this is not specific to either Mobitz (3:1 or > = high gd)
- Mobitz I: (Wenckebach) progressively longer PR, then conduction dropped
- Mobitz II: constant PR, but intermittent non conduction
- 3rd Degree: complete block i.e. no conduction
- Congenital lupus (Anti Ro/La)
SVT
- Atrial
- Sinus tachycardia (treat cause first line, beta blocker secondline)
- Atrial tachycardia aka a. ectopic/unifocal a./paroxysmal a. (betablocker first line, if not requiring cardioversion)
- Atrial fibrillation (betablocker first line, if not requiring cardioversion)
- Atrial flutter (betablocker first line, if not requiring cardioversion)
- Multifocal (chaotic) atrial tachycardia (different p wave morphologies, irreg-irreg)
- Atrioventricular (Junctional) (automated (AVN pacing) v reentrant)
- Junctional tachycardia: >100bpm (usually reentrant)
- atrioventricular reentry tachycardias (AVRT)
- accessory pathway can be antegrade (causing preexcitation i.e. short PR and delta wave) or retrograde ('concealed' as no sign on ECG)
- WPW (b-blocker, radio frequency ablation, NO digoxin as can increase conduction through accessory path)
- Lown-Ganong-Levine: short PR, no delta wave
- orthodromic = SVT with antegrade down AV / His then retrograde up accessory (most common)
- Permanent junctional reciprocating tachycardia (slow AVN, slow rentrant = stable)
- antidromic = SVT with antegrade down accessory and retro up AVN (<5%)
- accessory pathway can be antegrade (causing preexcitation i.e. short PR and delta wave) or retrograde ('concealed' as no sign on ECG)
- atrioventricular nodal reentry tachycardias (2 pathways in AV node, one fast one slow)
- atrioventricular reentry tachycardias (AVRT)
- Junctional tachycardia: >100bpm (usually reentrant)
Ventricular tachyarrhythmias
- VT
- Non-sustained
- Sustained
- Polymorphic (inc torsardes de pointes)
- VF
Long QT
- risk of polymorphic VT (called torsardes de pointes in pt with long QT when sinus)
- Rx Mg if conscious, debif if unconcious
- long QT syndrome: normal = 0.37-0.44s (nb can't exclude on a single ECG)
- Acquired
- drugs
- electrolyte disturbance
- Congenital
- 12 LQT locuses (1,2,5-7,11 = K efflux prob, 3,9,10,12 = Na influx, 8=Ca influx)
- Romano-Ward (AD i.e. heterozygous)
- Jervell and Lange-Nielsen syndrome (with sensorineural hearing loss) (AR i.e. homozygous)
- risk of polymorphic VT
- disorder of repolarisation
- Diagnosis is made using a scoring system (?On known genes now)
- Acquired
K
- high: disappearing p wave, prolonged PR, wide QRS, amplified R, short QT, peaked t-waves, can progress to sinusoidal > VF > asystole
- low: prolonged PR, prolonged QT, ST depression, flattened t-wave, u-waves (can lead to virtually any arrhythmia)
Antiarrhythmics
- Bradyarrhythmias
- Atropine
- Isoprenaline (Beta agonist: chronotropic, inotropic. It increases automaticity and atrioventricular nodal conduction)
- Pacemaker
- Tachyarrhythmias
- Adenosine (Depresses SN activity and slows AVN conduction)
- Amiodarone (Decreases SN and AVN automaticity, slows AVN and bypass tract conduction and prolongs refractory period of myocardial tissues)
- Digoxin (Slows heart rate, reduces AV nodal conduction by an increase in vagal tone and a reduction in sympathetic activity)
- Flecainide (Slows conduction, increases refractory period in all myocardial tissues/conduction tracts)
- Lignocaine (reduces automaticity of myocardial tissue)
- Sotalol (prolongs the refractory period of atria, ventricles and bypass tract)