Lecture 22-23

Question 1

What are some things the that can be determined by reading the EKG?

Answer 1

Rate, Rhythm, Hypertrophy, Infarction.

Question 2

How do you determine HR from and EKG?

Answer 2

1. Find R wave that falls on a heavy black line.
2. Count off 300, 150, 100, 75, 60, 50 for each consecutive heavy line
3. Where the next R wave falls determines the rate

Question 3

What is normal, bradycardia, tachycardia sinus rhythm rates?

Answer 3

Normal 60-100 beats/min
Bradycardia is < than 60 beats/min
Tachycardia is > than 100 beats/min

Question 4

What causes a premature beat?

Answer 4

Ectopic focus discharging spontaneously producing a beat which appears earlier than expected in the rhythm.

Question 5

Originates suddenly in an atrial ectopic focus and produces an abnormal P wave earlier than expected describes ____ ____ _____.

Answer 5

Premature Atrial contraction (PAC)

Question 6

Originates suddenly in an ectopic focus in a ventricle producing a giant ventricular complex describes _____ _____ _____

Answer 6

Premature Ventricular Contraction (PVC)

Question 7

Why is the QRS complex wider than normal in a PVC?

Answer 7

Depolarization originates in the myocardium (instead of conduction system) and therefore depolarization impulse conducted very slowly across both ventricles.

Question 8

Why is QRS taller/deeper than normal in a PVC?

Answer 8

PVC originates in one ventricle which depolarizes before the other and there is no simultaneous opposing depolarization from opposite sides. Therefore, QRS is very large.

Question 9

What are the rapid ectopic rhythms?

Answer 9

Flutter and Fibrillation

Question 10

What are the characteristics of atrial flutter?

Answer 10

1. Atrial flutter originates in an atrial ectopic focus
2. P waves occur in rapid succession and each is identical to the next
3. P waves look identical because they arise from the same ectopic focus
4. Only occasionally will the atrial stimulus penetrate the AV node and produce a QRS complex

Question 11

What are the characteristics of ventricular flutter?

Answer 11

1. Ventricular flutter is produced by a single ventricular ectopic focus firing at an extremely rapid rate
2. Forms a smooth sine wave
3. No P waves or T waves

Question 12

What is the characteristic of atrial fibrillation?

Answer 12

1. Caused by many atrial ectopic foci firing at rapid rates causing an exceedingly rapid, erratic atrial rhythm
2. No true P wave—just spikes appear

Question 13

T or F? You can live with atrial fibrillation.

Answer 13

True, it won’t directly kill you, however, major concern is development of blood clots due to POOLING OF BLOOD.

Question 14

What is the characteristic of ventricular fibrillation?

Answer 14

1. Caused by rapid-rate discharges from many ventricular ectopic foci producing erratic, rapid twitching of the ventricles
2. Because so many foci are firing at once, each only depolarized a small area of ventricle and produces “twitching” of ventricle instead of full contraction of ventricle

Question 15

T or F? Ventricular fibrillation cannot kill you.

Answer 15

False, No effective pumping—will directly kill you!

Question 16

____ _____ are electrical blocks which retard or prevent the passage of electrical (depolarization) stimuli.

Answer 16

Heart blocks

Question 17

The SA node stops its pacing activity for at least one cycle is characteristic of a ______ _______

Answer 17

Sinus Block. Also, the P waves are identical because the same SA node pacemaker is functioning before and after the pause (missed cycle)

Question 18

What is an AV block?

Answer 18

Delay in transmission of the impulse through the AV node

Question 19

What are characteristics of a 1st degree AV block?

Answer 19

1° AV Block- Results in longer pause before stimulating the ventricles; P-R interval prolonged (>0.20 seconds)

Question 20

What are characteristics of a 2nd degree AV block?

Answer 20

2° AV Block- progressive P-R prolongation until QRS is dropped.

Question 21

What are characteristics of a 3rd degree AV block?

Answer 21

3° AV Block (complete block)- Complete dissociation of atria and ventricles.

Question 22

How is a bundle branch block caused?

Answer 22

Caused by block of depolarization in the right or in the left bundle branch

Question 23

ischemia

Answer 23

Inverted T-wave

Question 24

What are the general characteristic of ischemia/infarct on an ECG?

Answer 24

Inverted symmetrical T waves
Elevated or depressed S-T Segments
Presence of significant Q waves makes the diagnosis of infarct

Question 25

What causes an T-wave inversion?

Answer 25

1. Prolonged depolarization of ventricles during ischemia changes pattern of repolarization 2. Ventricles repolarize in opposite direction to normal repolarization

Question 26

Ischemia/infarct: Elevated or depressed S-T segments is a sign of _____ injury.

Answer 26

acute. Can return to baseline with time.

Question 27

The presence of significant Q waves makes the diagnosis of ________.

Answer 27

Infarct. (Q-wave increases over time) Significant is considered > 1mm deep.