THE METHODS TO calculate rate, how to determine the axis of ECG, How to identify the rhythm of ECG

1. HEART RATE, RHYTHM, QRS AXIS
DR.N.PRAVEEN

2. HEART RATE CALCULATION

12. RHYTHM
 Sinus rhythm - normal P wave and QRS
 Atrial rhythm – Abnormal P wave and normal QRS
 Junctional rhythm – No P wave, normal QRS
 Ventricular rhythm – Abnormal QRS

14. Cardiac axis represents the sum of depolarisation vectors generated by
individual cardiac myocytes. Clinically is is reflected by the ventricular axis,
and interpretation relies on determining the relationship between the QRS
axis and limb leads of the ECG (below diagram)

15.  Methods of ECG Axis Interpretation
 There are several complementary approaches to estimating QRS axis, which
are summarized below:
 The Quadrant Method – (Lead I and aVF)
 Three Lead analysis – (Lead I, Lead II and aVF)
 Isoelectric Lead analysis
 Super SAM the Axis Man

16.  The most efficient way to estimate axis is to look at LEAD I and LEAD aVF.
 Examine the QRS complex in each lead and determine if it is Positive, Isoelectric (Equiphasic) or
Negative:
• A positive QRS in Lead I puts the axis in roughly the same direction as lead I.
• A positive QRS in Lead aVF similarly aligns the axis with lead aVF.
• Combining both coloured areas – the quadrant of overlap determines the axis. So If Lead I and aVF
are both positive, the axis is between 0° and +90° (i.e. normal axis).

22. Method 2: Three Lead analysis – (Lead I, Lead II and aVF)
Next we add in Lead II to the analysis of Lead I and aVF
•A positive QRS in Lead I puts the axis in roughly the same direction as lead I.
•A positive QRS in Lead II similarly aligns the axis with lead II.
•We can then combine both coloured areas and the area of overlap determines
the axis. So If Lead I and II are both positive, the axis is between -30° and
+90° (i.e. normal axis).

23. HOW TO DETERMINE AXIS ?

26. ISOELECTRIC METHOD

27.  tep 1: Find the isoelectric lead. The isoelectric (equiphasic) lead is the frontal lead
with zero net amplitude. This can be either:
• A biphasic QRS where R wave height = Q or S wave depth.
• A flat-line QRS with no discernible features.
 Step 2: Find the positive leads.
• Look for the leads with the tallest R waves (or largest R/S ratios)
 Step 3: Calculate the QRS axis.
• The QRS axis is at 90° to the isoelectric lead, pointing in the direction of the
positive leads.

28. QRS AXIS

30. Normal Axis

31. RAD

33. LAD

34. QUESTION

35. THANK YOU