Arrhythmias

Normal Conduction

Regular rhythm tachycardia

1. Sinus tachycardia - from SAN - infection, pain, exercise, anxiety, dehydration, hypovolaemia
2. Focal atrial tachycardia - a group of atrial cells act as a pacemaker out pacing the SAN - p wave morphology
3. Atrial flutter - atrial activity cycles the atria at 300 bpm giving a sawtooth baseline. The AVN passes some of these impulses on giving ventricular creates that are factors of 300 
4. Atrioventricular re-entry tachycardia - accessory pathway (eg in WPW) allows electrical activity from the ventricles to pass to the resting atrial myocytes creating a circuit. 'Orthodromic' direction, results in narrow QRS. Conduction in the other direction is 'antidromic' and results in broad QRS (atrial trigger ventricular contraction not via bundle of His)
5. Atrioventricular nodal re-entry - circuits form within the AVN causing narrow complex tachycardias
6. Junctional tachycardia - cells in AVN become pacemaker giving narrow QRS complexes. p waves may be inverted or late
7. Bundle branch block - any of the conditions above can result in a broad complex tachycardia if there is a BBB
8. VT - Similar to atrial flutter circuits - broad QRS. The plane of the circuit can rotate when in action seen as increasing and decreasing amplitude - torsades de pointes