EKG 2

Question 1

Intermodal and interatrial tracts

Answer 1

. Specialized pathways of cells which more rapidly conduct the impulse from SA node to AV node and both atria

Question 2

Bachmann’s bundle

Answer 2

. Major tract from RA to LA

Question 3

AV node

Answer 3

. Specialized region in the RA
. APs similar to SA node
. Region of very slow conduction

Question 4

Bundle of His

Answer 4

. Large bundle of specialized fibers arising from AV node

. Penetrates into the ventricles and divides into L and R bundle branches

Question 5

Purkinje fibers

Answer 5

. Mesh of specialized fibers w/ very fast conduction
. Rapidly spread impulse throughout much of R/L ventricles
. Primarily on inner portion of ventricular wall subendocardium)
. Makes ventricles depolarize from endocardium to epicardium

Question 6

P wave

Answer 6

. Depolarization of both atria

Question 7

QRS complex

Answer 7

. Depolarization of both ventricles
. Q wave: initial downward deflection of complex prior to any upward deflection, corresponds to depolarization of ventricular septum
. R wave: upward deflection of complex, corresponds to ventricular depolarization
. S wave: downward deflection after R wave, corresponds to ventricular depolarization too

Question 8

QS wave

Answer 8

. Single large deflection in place of QRS complex

Question 9

T wave

Answer 9

Repolarization of ventricles

Question 10

U wave

Answer 10

. Only seen occasionally (hypokalemia)

. Due to late repolarization of some region in ventricles

Question 11

Interval in EKG

Answer 11

. Periods of time that includes waves

Question 12

Segments

Answer 12

. Periods of time btw waves

Question 13

Segment in EKG recording

Answer 13

. Periods of time btw waves

. Normally isoelectric

Question 14

P-R interval

Answer 14

. Measured from beginning of P wave to beginning of QRS complex
. Represents time for atrial depolarization and delay through AV node
. Normal value 0.12-0.2 sec

Question 15

QRS interval

Answer 15

. Measured from beginning of Q wave (or R if no Q) to end of S wave
. Represents time for depolarization of ventricles

Question 16

QT interval

Answer 16

. From beginning of QRS complex to end of T wave
. Time for ventricular depolarization and repolarization
. Approx time for ventricular AP
. Dependent on heart rate

Question 17

QTc interval

Answer 17

. Normalized QT interval
. Normalizes QT interval to heart rate
. QT interval/ sq rt of R-R interval

Question 18

P-P interval

Answer 18

. Time btw consecutive atrial depolarizations
. Measured from beginning of one P to beginning of next P
. Can be used to determine atrial rate

Question 19

R-R interval

Answer 19

. Time btw consecutive ventricular depolarizations
. Measured from beginning of 1 QRS to beginning of next one
. Can be used to determine ventricular rate

Question 20

P-R segment

Answer 20

. Isoelectric period btw end of P wave and beginning of QRS complex
. Period btw atrial and ventricular depolarization
. Used as baseline to evaluate S-T segment displacement

Question 21

S-T segment

Answer 21

. Time btw end of QRS complex and beginning of T wave
. Corresponds to period btw completion of ventricular depolarization and beginning of ventricular repolarization
. Normally isoelectric
. Does not mean ventricles are at rest
. Corresponds to plateau of ventricular AP

Question 22

Most common abnormal interval/segment

Answer 22

. Prolonged P-R interval

. Indicative of slower than normal conduction through AV node