03 - Hypertrophy and Enlargement Flashcards
What is enlargement caused by?
Volume overload from aortic insufficiency or mitral regurgitation
Enlargement vs hypertrophy
Enlargement happens when the chamber dilates to accommodate an increased amount of blood
Hypertrophy refers to an increased muscle mass
What causes hypertrophy?
Pressure overload from systemic hypertension or aortic stenosis
Enlargement and hypertrophy cause ______ in wave duration, ______ in wave amplitude, and _____ of electrical axis
Increase - chamber takes longer to depol
Increase - chamber can generate more current
Shift - larger percentage of total current can move through expanded chamber
The ECG records the _________ of electrical forces at a given moment. The average vector of all of these is the _______. Its direction is called the
Instantaneous vector
Mean vector
Mean electrical axis
Complete depol can be represented by
Sequential vectors
The first vector represents ______ depol and each successive vector represents depol of the
Ventricles
The mean electrical axis points
Leftward and inferiorly
Represents the average during ventricular depol
Any mean QRS vector between -90 and +90 will produce positive QRS in
Lead I
Any mean QRS vector between 0 and 180 produces a positive QRS in
Lead aVF
If the QRS is positive in both lead I and aVF, the QRS axis lies between
0 and +90
With right axis deviation, the deflections will be positive in ______ and negative in ______ with the electrical axis between
aVF, lead I
+90 and 180
If the axis is between -90 and 180, this is called
The QRS complex will be
Extreme right axis deviation
Negative in both lead I and aVF
The electrical axis lies between 0 and 90 for
Left axis deviation
Left axis deviation has ______ aVF and ______ lead I
Negative
Positive
All of the information needed to assess atrial enlargement is on leads
II and V1
Lead II is oriented ______ to the flow of current through atria
Parallel
Lead V1 is oriented _______ to electrical flow
Perpendicularly
In right atrial enlargement, amplitude of the first portion of the P wave ______, _____ in width, and P wave axis may shift _______
Increases
No change
Rightward, beyond 90
Right atrial enlargement is often called
P pulmonale
Left atrial enlargement is called
P mitrale
Mitral valve disease is a common cause
The second portion of the P wave may increase in amplitude during
Left atrial enlargement
Increase in P wave duration
In left atrial enlargement, the terminal portion of the P wave should
Drop at least 1 mm below baseline in V1
Increase by at least .04 sec in duration
Causes of RVH?
Pulm HTN Tetrology of Fallot Pulm valve stenosis Ventricular septal defect Pulm disease
Why does RVH cause an electrical axis > 100 and right axis deviation?
It is reflective of the new electrical dominance of the usually “submissive” right ventricle
In RVH, lead I is slightly more
Negative than positive
No R wave progression
In V1, the R wave is larger than the S wave
In v6, the S wave is larger than the R wave
RVH
Causes of LVH?
Hypertension
Aortic stenosis
Athleticism
Hypertrophic cardiomyopathy
Left axis deviation in the limb leads can represent LVH but it is
Not very useful
Which criteria of LVH is the most accurate and sensitive?
R wave in aVL > 14 mm
These are the others:
R wave in aVF > 21 mm
R wave in lead I > 14 mm
R wave in lead I plus S wave in lead III > 25
In LVH, increased ____ amplitude over leads overlaying left ventricle
R wave
In LVH, increased _____ amplitude in leads overlying the right ventricle
S wave
Which criteria of LVH is the most selective and accurate?
R wave in V5 or V6 plus S wave in V1 or v2 exceeds 35 mm
Others:
R wave in V5 > 26 mm
R wave in V6 > 18 mm
R wave in V6 exceeds R wave in V5
Global hypertrophy can cause ______ ST segment and T wave
Downsloping
Inversion
