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Flashcards in ECG basics Deck (9)
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1

heart rate calculations
-standard paper speed
-time and length of dark/light lines
-formula

SPS: 25 mm/sec
dark: every 0.2 sec, so 5 "big boxes" per second
light: every 0.04 sec, so 1500 "small boxes" per minute

HR = # beats in 6 seconds x 10 = 1500/# light lines between beats

2

AV and IV conduction

AV = PR interval, less than or equal to 0.2 seconds
IV = QRS interval, less than or equal to 0.1 seconds

3

QTc interval

less than or equal to 0.45 seconds
-from onset of QRS to end of T (depol and repol)
-QT interval varies with HR
-QTc = QT/square root of R-R interval

4

right bundle branch block appearance

prolonged QRS
-late upward deflections in right sided leads (V1, aVR)
-late downward deflections in left sided leads (1, V6)

5

left bundle branch block appearance

prolonged QRS
-late upward deflection in left sided leads (1, aVL, V6)
-late downward deflections in right sided leads (V1)

6

AV conduction levels of heart block

1st degree: prolongation of PR interval only
2nd degree: some but not all beats are conducted
-Mobitz type 1: gradually increasing PR interval until a P wave is not conducted
--following P wave is conducted with shorter PR interval
--not serious, more common
-Mobitz type 2: sudden non-conducted P waves with no change in PR intervals
--more serious, but uncommon; may go to 3rd degree
3rd degree: no P waves are conducted, need pacemaker

7

complications of 3rd degree heart block

-escape rhythm
-junctional bradycardia with BBB or ventricular bradycardia (idioventricular rhythm)

8

ventricular tachycardia

HR > 100/min originates from one of the ventricles, resulting in a wide QRS complex
-potentially life threatening b/c can degenerate into ventricular fibrillation resulting in sudden death

9

narrow VS wide QRS complexes in tachycardias

narrow: QRS < 100 ms are supraventricular origin, with intact IV conduction
wide: QRS > 120 ms are supraventricular rhythm with aberrant IV conduction (RBBB, LBBB), or ventricular tachycardia

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