How to read ECG for Beginners?

How to read ECG for Beginners?

1.    First you should look at Rhythm is t steady or not? To look at rhythm you measure the R and the next R waves if they are equal then the rhythm is steady.

2.    Calculate Heart rate: one of the most important things to do but How? It's easy by counting the large squares between R-R interval then do the calculation
Heart rate = 300/Number of large squares.

 

Heart rate abnormalities:
If the sum of calculation is less than 60 beats/minute then the patient has bradycardia
If Heart rate more than 100 the patient has tachycardia

3.    Examine the waves P,QRS,T is they are normal or inverted or absent

4.    Check P-R interval normal it is 3-4 small squares or .04 seconds.

5.    Detect the mean electrical axis: refers to the net ventricular depolarization direction.

How to calculate MEA by calculate net deflection of QRS complex in the LEAD I and aVF
Net deflection is QRS is net Positive or net Negative or isoelectric. Calculate it by substract Down waves from up waves.

Normally the QRS is positive in LEAD I and aVF and the MEA is between -30 and 110 but there is some abnormalities which causes:

Right axis deviation - QRS is Negative in LEAD I and Positive in aVf the axis between 0 and -90 -as

• right heart hypertrophy or dilation
• Conduction defect of right ventricle
• Acute myocardial infarction of left side of the heart

Left axis deviation – QRS is positive in LEAD I and Negative in aVf the axis between 0 and -90 - as

• left heart hypertrophy or dilation
• Conduction defect of left ventricle except for posterior bundle branch
• Acute myocardial infarction of right side of the heart