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Flashcards in ECG axis and hypertrophy Deck (18):

What is the normal Heart axis?

90 to -30 degrees


How do you quickly determine if heart axis is normal?

Check for positive QRS in Lead I and AvF

(If AvF is negative, a positive II lead means the axis is still normal, but between 0 and -30 degrees)


How can you define the axis precisely?

Look for the limb lead with the most biphasic QRS. The axis is aproximately perpendicular to this.

I.e if it is most biphasic in lead I (0). Then the the axis must be +/- 90 degrees.


What is the normal P wave axis?

0 - 70
(0-90 in children)


What is the normal T-wave axis?

Within 50-60 degrees of the QRS axis


What can be the cause of left axis deviation?

Left ventricular hypertrophy


What can be the cause of right axis deviation?

Huge right ventricular hypetrophy
- (COPD -> pulm. hypertension)
- Congenital with big pressure overload of RV


What are three signs of enlargement/hypertrophy?

1. Increased wave duration
2. Increased wave amplitude
3. Axis deviation


What are ECG signs of right atrial enlargement?

Right axis deviation of the P wave
Tallest P no longer in II, but aVF or III

Diagnostic: P wave > 2,5mm in at least one inf. leads

P pulmonale (severe lung disease common cause)


How do you diagnose LA enlargement?

Terminal part of P wave drop more than 1mm below isoelectric line in V1 + at least 0.04 s duration

(No axis deviation - LA is normally dominant)

P mitrale (mitral valve disease is common cause)


What is two simple criteria for diagnosing RV hypertrophy, looking at V1 and V6?

V1: R > S wave
V6 S > R wave

also QRS axis should be > 100


What are the two most common causes of RV hypertrophy?

Pulmonary disease
Congenital heart disease


What are four criterias in the precordial leads for diagnosing LV hypertrophy?

1. R amplitude in V5 or V6 + S amplitude in V1 or V2 > 35mm

2. R amplitude in V5 > 26 mm
3. R amplitude in V6 >20 mm
4. R amplitude in V6 > V5


What are four criterias in the limb leads for diagnosing LV hypertrophy?

1. R amplitude in aVL > 11 mm
2. aVF > 20 mm
3. lead I > 13 mm
4. R amp in I + S amp in III > 25 mm


What is the most aacurate criteria for diagnosing LV hypetrophy, combining limb and precordial leads?

Cornell criteria:

R amplitude in aVL + S amplitude in V3
> 20 in women
> 28 in men


What the top 2 causes of LV hypertrophy?

systemic hypertension
valvular disease


What happens to the duration of the QRS complex in ventricular hypertrophy?

May be slightly prolonged, but rarely beyond 0.1 s


What secondary repolarization changes can be seen in ventricular hypertrophy?

1. downsloping ST segment depression
2. T - wave inversion ( T axis different from QRS)

RV - seen in V1/V2
LV -I, AvL, V5, V6 - more common

Repolarization abnormalities usually accompany severe hypertrophy