17. EKG Evidence of Hypertrophy and Ischemia Flashcards Preview

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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?

-Diminish voltage
-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
-Pulmonary hypertension
-Pulmonic valve disease


How is LV hypertrophy assessed on an EKG?

Scott's Criteria:
-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?

-Early repolarization
-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


In what leads are T waves allowed to be inverted? Why?

aVR, III, V1 b/c these are the only 3 leads whose (+) poles are to the right of the body's mid-line