Medical Data Interpretation

Cardiac axis Cardiac axis describes the overall direction of electrical spread within the heart. In a healthy individual the axis should spread from 11 o’clock to 5 o’clock. To determine the cardiac axis you need to look at leads I,II and III. Normal cardiac axis In normal cardiac axis:     Lead II has the most positive deflection compared to Leads I and III . Right axis deviation In right axis deviation:      Lead III has the most positive deflection and Lead I should be negative      This is commonly seen in individuals with right ventricular hypertrophy Left axis deviation In left axis deviation:      Lead I has the most positive deflection      Leads II and III are negative      Left axis deviation is seen in individuals with heart conduction defects

Heart Rhythm The heart rhythm can be regular or irregular. Irregular rhythms can be either:      Regularly irregular (i.e. a recurrent pattern of irregularity)      Irregularly irregular (i.e. completely disorganised) Mark out several consecutive R-R intervals on a piece of paper, then move them along the rhythm strip to check if the subsequent intervals are the same. Hint – if you are suspicious that there is some atrioventricular block, map out the atrial rate and the ventricular rhythm separately (i.e. mark the P waves and R waves). As you move along the rhythm strip, you can then see if the PR interval changes, if QRS complexes are missing or if there is complete dissociation between the two.