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Flashcards in Diagnostic Features of ECG Deck (18):

Associate each of the waves on ECG with what's going on in the heart:
P wave
QRS complex
T wave

P wave = atrial depolarization
QRS complex = ventricular depolarization
T wave = ventricular repolarization


If your QRS takes up 3 heavy lines, what is your HR?

100 bpm

HR = 300 / # heavy lines between 2 QRS's
HR = 1500 / # mm between 2 QRS's


EKG leads measure:

1. Two different points on body (bipolar)
2. One point on the body and a virtual reference point with 0 potential in the center of heart (unipolar)


Depolarization moving ___ a positive electrode produces a ___ deflection

Toward a positive electrode produces a positive deflection


V1 & V2 are what type of leads?

R-sided chest leads, measuring R ventricle


V5 & V6 are what type of leads?

L-sided chest leads, measuring L ventricle


If have LV hypertrophy, expect to see large R waves on which leads?

L-sided leads: V5 & V6, sometimes I, aVL


More muscle = more volts = greater amplitude can be seen in which cardiomyopathy?

Ventricular hypertrophy


If have RV hypertrophy, expect to see large R waves on which leads?

R-sided leads: V1 & V2


How does demand ischemia change the EKG?

Depression of ST segment


How does acute coronary artery obstruction change EKG?

T wave inversion


How do demand ischemia and acute coronary obstruction differ?

Demand - normal ECG @ rest
Obstruction - abnormal even at rest


Transmural infarcts produce which kinds of waves?

Q - waves;
Absence of normal transmural vector produces a negative deflection in leads over infarcted myocardium


What rules can you use to determine if you can associate infarct with a Q wave?

1. Is > 1/4 of the amplitude of the R wave
2. Is one small box (0.04) seconds wide
3. Is usually in at least 2 leads reflecting the same region of the LV


Transmural vs subendocardial infarct as seen by ECG

Transmural: ST elevation with Q waves
Subendocardial: ST depression without Q wave


Why are we worried about prolonged QT interval? What is normal?

Increases susceptibility to arrhythmias
Normally: < 1/2 of total difference of 1 QRS to the next
Bad if > 1/2


What acquired things prolong QT interval?

Hypokalemia, Hypomagnesemia, Class 1A or 3 anti-arrhythmic drugs, Hypothermia


How does hypercalcemia affect ECG?

Shortened QT interval