Flashcards in ECG and ECG waves Deck (27)
The heart impulse is initially generated where?
SA node has its own intrinsic rhythm/rate of depolarization of what?
80-100 times per minute
Impulse from SA node spreads through the __________ causing both atria to contract simultaneously.
Impulse spread from intra-atrial bundles to where?
AV node has intrinsic rhythmicity/rate of depolarization of what?
40-60 times per minute
When SA nodal rhythm is superimposed on AV nodal rhythm, what is the result?
70 beats/ min
The AV node impulse is transmitted to what?
The bundle of His
From the bundle of His the impulse travels where?
To right and left bundle branches located in the muscular part of interventricular septum.
Impulse travels slowest where? Fastest?
Slowest - AV node (0.5 m/sec)
Fastest - purkinjie fibers (4 m/sec)
The rate of depolarization is slowest where? Fastest?
Slowest - purkinjie fibers
Fastest - SA node
PR interval extends from? How long?
P wave to beginning of Q wave
What is a 1st degree AV block?
Causes prolonged PR interval (>200 msec)
This AV block causes progressive prolonged PR interval with dropped beats.
2nd degree AV block
2nd degree AV block is aka
Mobitz 1 - Wenckebach phenomenon
What is a 3rd degree AV block?
No association btw P and QRS complex
Ventricular depolarization (
QT interval extends from?
Beginning of Q wave to start of T wave
ST segment extends from?
End of S wave to start of T wave - isoelectric line
Is atrial depolarization seen on ECG?
Why is atrial depolarization not seen on ECG?
Buried in QRS complex
Increase in pressure without change in volume?
Isovolumic contraction occurs between what?
Closure of AV valves and opening of aortic valve
How much of the blood is ejected?
70 mL of the 120 mL, approx. 60%
What is a decrease in pressure without a change in volume?