Cardiovascular System 2: Arrhythmias 1&2

ARRHYTHMIAS 1 & 2
When diagnosing arrhythmias:

 Look at QRS – is it broad or narrow?
 Look at P wave in relation to QRS complex.

Normal Sinus Rhythm: P:QRS ratio is a 1:1 ratio.

Calculate Heart Rate on an ECG: 300/no. of squares between 2 QRS complexes’.

TACHYARRHYTHMIAS

If irregular rhythm – then it is atrial fibrillation.
If regular rhythm – with narrow QRS (atrial flutter or super ventricular tachycardia) or broad
QRS (ventricular tachycardia).

 If they have tachyarrhythmia’s then they’ll have palpitations.
 Hyperthyroidism can cause atrial fibrillation.
 Hypothyroidism can cause bradycardia.
 Anaemia – increase risk of arrhythmia.

Sinus Tachycardia

 Regular narrow QRS.
 P waves visible and normal P:QRS ratio (1:1).
 80-120 bpm.

Ectopic Beats

 Missed beats and thumps.
 Usually benign.

Supraventricular Tachycardia

 Rapid more than 100 bpm.
 AV node re-entry.
 Regular narrow QRS complex.
 Can be terminated with valsalver maneuver or with adenosine.

AV Node Re-entry Tachycardia

 Have 2 pathways through the AV node.
 An ectopic atrial beat comes and blocks the fast pathway and conducts slow
pathway instead.
 Therefore, get re-entry down slow pathway and back up the fast pathway
repeatedly. So you get atria and ventricles contracting at the same time.