Hypertrophy and Enlargement Flashcards
Most hypertrophy is caused by _______
pressure overload
causes of pressure overload
systemic HTN, aortic stenosis
What does ‘hypertrophy’ refer to?
increase in muscle mass
What does ‘enlargement’ refer to?
dilatation of a particular chamber
Most enlargement is caused by _______
volume overload
causes of volume overload
valvular diseases
causes left ventricular enlargement
aortic insufficiency
causes left atrial enlargement
mitral insufficiency
What wave(s) do you look at to assess atrial enlargement?
P wave
What wave(s) do you look at to assess ventricular hypertrophy?
QRS complex
What are the 3 ways enlargement/hypertrophy can manifest itself on an EKG?
- increase in wave duration (takes longer to depolarize)
- increase in amplitude (more current generated)
- electrical axis shift (more current moves through an expanded chamber)
If the QRS complex is normal it should be _____ in leads _____ and _____
positive in leads I and aVF
In a RIGHT axis deviation, the QRS will be _____ in lead I and _____ in lead aVF
negative in lead I and positive in lead aVF
In a LEFT axis deviation, the QRS will be _____ in lead I and _____ in lead aVF
positive in lead I and negative in lead aVF
In an EXTREME RIGHT axis deviation, the QRS will be _____ in lead I and _____ in lead aVF
negative in lead I and negative in lead aVF
What leads should you look at to assess atrial enlargement? What should the P waves in these leads look like?
leads II and V1
P wave in lead II should be positive
P wave in lead V1 should be biphasic
What occurs in RIGHT atrial enlargement?
the amplitude of the 1st portion of the P wave increases; the tallest P wave may appear in lead III or aVF
How do you diagnose RIGHT atrial enlargement?
P waves have an amplitude exceeding 2.5 squares in leads II, III and aVF (inferior leads)
How do you diagnose LEFT atrial enlargement?
terminal portion of P wave should drop more than 1 small square below the isoelectric line in V1 and the terminal portion of the P wave should be at least 0.04 sec (1 small square) in length
Another name for RIGHT atrial enlargement and cause
P pulmonale; severe lung disease
Another name for LEFT atrial enlargement and cause
P mitrale; mitral valve disease
The most common causes of RIGHT ventricular hypertrophy
pulmonary disease, congenital heart disease
What EKG changes are reflected with RIGHT ventricular hypertrophy?
QRS in lead I should be more negative than positive
In lead V1 the R wave is larger than the S wave
I lead V6, the S wave is larger than the R wave
Which leads are more sensitive to diagnosing LEFT ventricular hypertrophy?
In general the precordial leads (V1-V6) are more sensitive than the limb leads
What are the 4 criteria for diagnosing LEFT ventricular hypertrophy in the precordial leads?
1) the R wave amplitude in lead V5 or V6 PLUS the S wave amplitude in V1 or V2 is greater than 35mm
2) the R wave amplitude in lead V5 exceeds 26mm
3) the R wave amplitude in lead V6 exceeds 18mm
4) the R wave amplitude in lead V6 exceeds the R wave amplitude in V5
What are the 4 criteria for diagnosing LEFT ventricular hypertrophy in the limb leads?
1) R wave amplitude in lead aVL exceeds 13 mm
2) R wave amplitude in lead aVF exceeds 21mm
3) R wave amplitude in lead I exceeds 14 mm
4) R wave amplitude in lead I PLUS the S wave amplitude in lead III exceeds 25 mm
What are the leading causes of LEFT ventricular hypertrophy?
systemic HTN and valvular disease
