Axis and Atrial Enlargement Flashcards
the direction of the depolarization as it moves through the heart
mean electrical axis
which limb leads are used to figure out axis?
Lead I and aVF
what is the axis if both lead 1 and aVF are mostly positive?
normal axis
what is the axis if lead 1 is mostly negative and aVF is mostly positive?
right axis deviation
what is the axis if lead 1 is mostly positive and aVF is mostly negative?
left axis deviation
what is the axis if lead 1 and aVF are both mostly negative?
extreme right axis
what is an important cause of right axis deviation?
right ventricular hypertrophy
what is an important cause of left axis deviation?
left ventricular hypertrophy
In a biphasic P wave in lead V1, what does the first part represent?
right atrial depolarization
In a biphasic P wave in lead V1, what does the second part represent?
left atrial depolarization
what 2 criteria should be met to diagnose right atrial enlargement?
- tall P wave in lead 2
- increased right atrial component in V1
what is the main cause of right atrial enlargement?
severe lung disease (p pulmonale)
briefly, how does p pulmonale cause right atrial enlargement?
blood reverses from lungs into right ventricle
then into right atrium
what 2 criteria should be met to diagnose left atrial enlargement?
- longer than 0.12 sec (3 small boxes) in lead 2 - m-shaped
- second part of P wave in V1 is deeper and longer than 1 small box
what is the main cause of left atrial enlargement?
aortic or mitral valve disease (p-mitrale)
