Flashcards in 17. EKG Evidence of Hypertrophy and Ischemia Deck (19):
How is the EKG evidence of hypertrophy and ischemia different than that of arrhythmias?
-Primarily affects voltage (Y axis of EKG) rather than time (X axis)
-Conditions persist for minutes to days and present in each complex unlike the on/off nature of arrhythmias
How does hypertrophy affect voltage?
Hypertrophy adds myocardial mass --> more voltage
How does death of myocardial tissue affect an EKG?
-Pathological Q waves
How does transient ischemia affect an EKG?
Delays & distorts repolarization --> elevates/depresses the ST segment
What is the significance of a flipped T wave?
"Soft indication" of ischemia
In what order is hypertrophy assessed?
RA --> LA --> RV --> LV
What characterizes RA enlargement on an EKG? Cause? What lead?
Extra mass "stacked" around the SA node produces a tall (>2.5 mm), peaked P wave in lead II
What characterizes LA enlargement on an EKG? Cause?
-Adds mass far to the left of the SA node, making for a long P wave > 0.12 sec, often w/ a 0.04 sec "notch"
-Commonly results from mitral valve abnormalities
What characterizes RV enlargement on an EKG?
-A large upright R waves in lead I
-R wave is greater than S wave in V1
-Peaked, tall P wave in lead II
-"Strain" pattern (inverted T wave, especially in V1 and V2)
What are the common causes of RV hypertrophy?
-Increased pulmonary vascular resistance due to emphysema and other chronic pulmonary diseases
-Pulmonic valve disease
How is LV hypertrophy assessed on an EKG?
-measure the deepest S wave in lead V1 or V2 and add it to the tallest R wave in leads V5 or V6
-a sum > 35 mm suggests LVH
Summarize the steps of analyzing an EKG for hypertrophy.
1. Measure the P wave height in lead II: > 2.5 mm is RA hypertrophy
2. Measure P wave duration in lead II: >/= 0.12 sec w/ notch is LA hypertrophy
3. R taller than depth of S wave in lead V1 is RV hypertrophy
4. Measure deepest S wave in V1 or V2 and add this to the tallest R wave in V5 or V6. > 35 mm is LV hypertrophy
What does the final diagnoses of chamber hypertrophy require?
What distinguishes athletic LV hypertrophy from pathologic LV hypertrophy?
-Athletic: LV hypertrophy only meets voltage criteria
-Pathologic (due to valve disease, hypertension, cardiomyopathy): often have additional signs like axis deviation, atrial involvement, depolarization abnormalities like "strain" pattern of T wave
What are the 3 criteria that are examined in each lead for ischemia? What does each mean?
-Pathologic Q waves > 0.03 sec suggest dead myocardium from an old MI
-ST elevation > 1mm represents acute, transmural ischemia (MI is starting)
-ST depression > 1mm represents sub-endocardial ischemia (reversible by lowering demand on the heart)
-T wave inversions are a "soft" indication of ischemia
What are the 2 varieties of ST elevation?
-Acute transmural ischemia
What characterizes early repolarization on an EKG?
-ST elevation that is seen in young athletes
-Concave upward (nike swoosh)
-Accompanied by other signs of athleticism
What characterizes an acute transmural ischemia on an EKG?
ST elevation concave downward suggest an MI is starting