Introduction to the ecg Flashcards Preview

Physiology Exam 2 > Introduction to the ecg > Flashcards

Flashcards in Introduction to the ecg Deck (24):
1

direction of action potentials from SA node

ALL DIRECTIONS

2

electrode placement and resultant signal

largest signal is PARALLEL vectors, no signal is perpendicular

3

einthovens triangle

three locations for electrodes- right arm, left arm, ll. recording is always at the POSITIVE end

4

Nodes and charge

LL always+, RA always -

5

what are the three main leads for EKG?

Lead I (RA to LA), Lead II (RA to LL), and Lead III (LA-LL)

6

what are the sections in an EKG waveform

P, QRS, T, U

7

P wave

atrial depolarization after SA firing

8

QRS

ventricular depolarization and atrial repolarization

9

T

ventricle depolarization

10

QRS waveform is composed of

four mean vectors, each with length related to size of muscle. LBB fires faster than the right.

11

augmented chest leads

AVL: -30, AVR: -150, AVF (+90)

additional positive electrodes referenced against the others.

12

vectors analysis

determine net amplitude of QRS- count number of boxes, transfer values to axes, draw perpendicular lines, draw resultant vector

13

inspection method

find lead without signal- mean vector is at a right angle!

14

what is a lead

a lead is a pair of electrodes. Only worry about two at a time. provideys electrical axis.

15

x axis and y axis of waveform

x axis: time, y axis: amplitude

16

PR segment

amount of time to pass through juncitional fibers of AV

17

ST segment

depolarized ventricles, plateau phase of ventricular AP

18

QRS segment vector 1

the q wave: points to the right, because conduction is LR (Left depolarizes faster). negative signal, towards neg electrode

19

QRS segment vector 2

R wave, depolarization of axis . down lead II, large mass of tissue

20

QRS segment vector 3

R wave, ventricular wall depolarization outward, to left cause of larger mass

21

QRS segment vector 4

S wave, end of V depolarization, upwards because base of heart depolarizes last. (neg, towards neg)

22

normal aVR

negative signal, depolarization away from positive,

23

normal aVL

small Q/R, almost right angle to depolarization

24

normal aVF

positive, points towards lead