ECG chamber enlargment - Hefnawy

Question 1

what do you do 1st when determining a cardiac disease process?

Answer 1

get an EKG - can give you the 1st clue

Question 2

ways to get chamber enlargement

Answer 2

1. dilation –> sarcomeres stretched due to volume overload (preload) or eccentric hypertrophy
2. hypertrophy –> increase in cardiomyocyte size due to pressure overload (afterload) or concentric hypertrophy

fibrosis and scarring in both situations

Question 3

how do you get hypertrophy from an increase in afterload?

Answer 3

• increase in resistance –> thickened walls
• ex. RV hypertrophy in pulmonary HTN
• ex. LV hypertrophy in systemic HTN

Question 4

atrial depolarization

Answer 4

• lead 2 –> both right and left atrial depolarization travel in same direction –> + reflection seen as 1 bump
• V1 –> RA travels in same direction (+ reflection) and LA travels in opposite direction (- reflection) –> 2 separate bumps
• RA depolarizes before LA bc it contains SA node

P wave no more than .12 sec duration and 2.5mm amplitude in lead 2

Question 5

right atrial abnormality (RAA)

Answer 5

• interfere with atrial emptying –> increase atrial pressure
• associated with RV enlargement (ex. pulmonary HTN with backup of fluid)

Question 6

ECG findings in RAA*** - aka P pulmonale

Answer 6

• lead 2 –> peaked 1st component of P wave** due to exaggerated + from RA
• lead V1 –> more + in the initial wave than - on the P wave**
• may see strained/depressed ST due to associated ventricular issues
• greater than 2.5mm on amplitude for P wave

look at lead 2 for RAA

Question 7

left atrial abnormality (LAA)

Answer 7

• anything that causes resistance/pressure in left atrium

- ex. aortic stenosis/regurge, mitral stenosis/regurge

Question 8

ECG findings of LAA** - aka P mitrale

Answer 8

• lead 2 –> bifid M wave** due to exaggerated 2nd component of P wave; also widening of P wave**
• lead V1 –> more neg exaggeration (wider and deeper) in the 2nd component than + in the 1st component of P wave**

Question 9

left ventricular hypertrophy (LVH)

Answer 9

• due to an increase in the afterload of the LV (anything that increases pressure/tension)
• ex. systemic HTN, aortic stenosis/coarctation
• may have left atrium enlargement, left axis deviation, and widened QRS

Question 10

QRS wave

Answer 10

• 1st peak that comes up after P wave is R**
• 1st peak that comes down after R is S**
• Q –> depolarization of septum from left to right
• R –> depolarization heading towards lead 2
• S –> depolarization of the tip of LV heading away from lead 2

Question 11

voltage criteria for LVH**

Answer 11

• V3 is equiphasic (transition)
• exaggerated + R in leads 1, aVL, V5, V6 bc are on left side of heart**
• exaggerated - S in leads V1,V2 bc are on right side of heart**
• left bundle branch block

Question 12

sokolow-lyon scale - definitive diagnosis of LVH

Answer 12

• combine exaggerated R on left side and exaggerated S on right side of heart –> >or= 35mm
• generally, R wave in aVL >11mm

Question 13

non-voltage criteria for LVH**

Answer 13

• also have strained/depressed ST-T wave and asymmetrical inversion of T wave secondarily due to stressed ventricle** –> worse prognosis leading to myocardial problems
• strained ST and inverted T in leads 1, aVL, V5,V6**

Question 14

asymmetrical inversion of T waves seen in where??**

Answer 14

• LVH and RVH –> slope is different

- due to stressed ventricles

Question 15

right ventricular hypertrophy (RVH)

Answer 15

• anytime the RV cannot empty

- ex. pulmonary stenosis/HTN, mitral stenosis, emphysema

Question 16

ECG in RVH**

Answer 16

• exaggerated + R in V1**
• exaggerated - S in V5,V6**
• faster QRS duration
• right axis deviation >or= 110 degrees
• secondary strained/depressed ST-T and asymmetrical inversion of T wave in leads V1-V3**
• right bundle branch block

-LV usually predominates and forms QRS axis, so need severe RVH to overcome LV vector