doctor's tips for ECG

First degree AV heart block

ECG characteristics

· Atrial rhythm : regular

· Ventricular rhythm : regular

· Atrial rate : usually normal ( 60 to 100 beat / minute )

· Ventricular rate : usually normal ( 60 to 100 beat / minute )

· P wave : present - uniform configuration

· PR interval : constant - lengthened - greater than 0.12 seconds

· QRS complex : duration and configuration usually normal

· Other : each P wave is followed by QRS complex , there

are nil non-conducted beats

Possible causes

· Acute inferior myocardial infarction

· Degeneration of conduction system

· Hyperkalaemia

· Digoxin toxicity , Quinidine toxicity

· Rheumatic fever

· Acute myocarditis

· Calcium channel blockade administration

· May occur in well trained athletes

· Common in elderly people without evidence of heart disease

Treatment

· Usually nil required

· Treatment of cause

Second degree AV heart block - Mobitz Type I (Wenckebach)

ECG characteristics

· Atrial rhythm : regular

· Ventricular rhythm : irregular , R-R interval shortens progressively

until P wave appears without QRS complex

and then cycle repeats.

· atrial rate : exceeds ventricular rate

· P wave : present - usually normal configuration

· PR interval : progressively lengthening , until P wave appears

without QRS complex , PR interval following

non conducted beat is shorter than the preceding

PR interval

· QRS complex : duration and configuration is usually normal

Complex is periodically abnormal

Possible causes

· Inferior wall myocardial infarction

· Cardiac surgery - particularly AVR and MVR

· Vagal stimulation

· Digoxin toxicity

· Medication administration (Propanolol , Quinidine , Procainamide Verapamil)

· Bacterial / viral / fungal infection

· Acute infection - i.e. Rheumatic fever

· Electrolyte imbalance

· Uraemia

· May occur in well trained athletes

This type of block is usually temporary and benign and seldom requires pacing

Treatment

· No treatment required if asymptomatic , monitor for progression of heart block

· If symptomatic -atropine or isuprel may be administered

-if atropine or isuprel not effective - consider pacing therapy