The Electrocardiogram Flashcards
Can give a vasoconstrictor to increase
afterload
Fick Principle:
calculates the rate at which a substance is being added to or removed from the blood as it passes through an organ
Fick equation
Xtc = Q × ([X]a – [X]v) Q = Xtc / ([X]a – [X]v)
Cardiac Index =
Cardiac Output / body surface area
Relates cardiac function to the size of the individual
Normal values range from 2.6 – 4.2 L/min per square meter
PR interval
from start of P to the beginning of Q
Conduction time through atria & AV node (120 – 200 msec)
P wave
atrial depolarization
QRS complex
start of Q to the end of S
Ventricular depolarization
QT interval
start of Q to the end of T
Total duration of ventricular systole
(
ST segment
end of S to the beginning of T
the plateau phase of ventricular AP
T wave
ventricular repolarization
ECG paper: small box = ___seconds
.04 seconds or 40 ms
ecg paper: 10 mm = ____mv
1 mv
End of PR Interval: where nothing is seen on ecg, what is happening
- Depolarization wave reaches non-muscular (non-excitable) border between atria & ventricles
- Atrial muscle cells depolarized (Phase 2)
- Ventricular cells still resting
- Electrical field created during passage through AV node too small to see
ST Segment: nothing is seen on ecg, what is happening
- No rapid changes in membrane potential occurring anywhere
- Atrial cells returned to resting
- Ventricular cells depolarized (Phase 2)–>can be elevated/depressed in myocardial injury or inadequate blood flow
Left Axis Deviation:
