Premature ventricular contractions
ECG characteristics
· P wave : absent
· PR interval : not measurable
· QRS complex : occurs earlier than expected , bizarre
configuration , duration greater than 0.12 sec.
· T wave : occurs opposite direction to QRS complex
· Other : a compensatory pause may follow the T wave.
Possible causes
· Increased catecholamine release
· Hypoxia
· Hypokalaemia
· Hypocalcaemia
· Hypomangnesaemia
· Myocardial infarction / ischaemia
· Hypothermia
· Mechanical irritability i.e. Swan Ganz or pacemaker insertion
· Digoxin toxicity
· Sympathomimetic medication i.e. Adrenaline, Isuprel
· Exercise
· Excessive Alcohol or Caffeine ingestion
· Hypercapnia associated with C.O.A.D
· Cigarette smoking
Treatment
· Resolve the cause
*Maintenance of potassium (Hypokalaemia:- most common cause)
*Maintenance of normothermia
*Sympathomimetic medication induced
ECG characteristics
· Atrial rhythm : can not be determined
· Ventricular rhythm : usually regular - may be slightly irregular
· Atrial rate : can not be determined
· Ventricular rate : usually rapid (100 - 200 beats per minute)
· P wave : usually absent , may be obscured by the QRS
complex , retrograde P waves may be seen
· PR interval : not measurable
· QRS complex : duration exceeds 0.12 seconds , bizarre
appearance , usually with increased amplitude
· T wave : direction is opposite QRS complex
· Other : fusion beats , capture beats
Possible causes
· Hypokalaemia, hypocalcaemia, hypomangnesaemia
· Hypothermia
· Acute myocardial infarction / ischaemia
· Rheumatic heart disease
· Mitral valve prolapse
· Congestive heart failure
· Cardiomyopathy
· Pulmonary embolism
· Drug toxicity (Digoxin, Quinidine, Procainamide)
· Hypertensive heart disease
· Cardiac disease
· Ventricular aneurysm
Treatment
· Conscious: - treat cause
perform cough CPR
consider drug therapy (Magnesium, Calcium, Lignocaine, Amiodarone, Bretylium, Procainamide)
cardioversion
· Unconscious: - Defibrillation, and CPR
Treat the cause
Consider drug therapy (Magnesium, Calcium, Lignocaine, Amiodarone, Bretylium, Procainamide)
