Lecture 2: ECG B6

Question 1

Leads that go around the heart at mid-chest. Used to localize infarcts

Answer 1

Precordial leads

Question 2

R-wave progresses from _________ to more ___________ through V1-V5.

Answer 2

negative to more positive

Question 3

Vector that shows where most depolarization occurs. (where most muscle mass is)

Answer 3

Mean electrical axis

Question 4

Why is the sum of al QRS vectors usually at 60 degrees?

Answer 4

that is pointing down and to the left towards the left ventricle (largest chamber with most muscle mass in heart)

Question 5

If MEA changes, then heart has changed shape. What can this lead to?

Answer 5

Hypertrophy/ dilation in response to cardiac diseases. (Quick and dirty way of seeing how heart changes shape) Or which way depolarization is going to.

Question 6

Calculating MEA. Which leads do you look at?

Answer 6

Lead I and aVF

Combining these 2 allows a good approximation of MEA

Question 7

If someone is healthy, where will Lead I and aVF show up?

Answer 7

Lead I will be positive

aVF will be positive

Question 8

There are two responses that the heart can do when it is under stress… what are they?

Answer 8

Hypertrophy- cells get bigger
-response to hypertension
-heart wall gets thicker
Dilation-chamber gets bigger
-fills with more load
-response to volume overload

Question 9

True/False: Atrial changes can overpower Ventricle changes. Right side changes can overpower right side changes.

Answer 9

False: Ventricle changes can overpower Atrial changes. (they are bigger)
Left side changes can overpower right side changes

Question 10

You receive an ECG with a positive R wave in Lead I and a negative R wave in aVF. What is this persons MEA?

Answer 10

Left axis

Question 11

You receive an ECG with a pos R wave in Lead I and a neg R wave in aVF. Which of the following could result in such an ECG change?

Answer 11

Left ventricular hypertrophy (most likely)

Left atrial hypertrophy

Question 12

ANy alteration to normal rhythm, regularity, origin or conduction of the heart beat.

Answer 12

Arrhythmias

Question 13

To determine Arrhythmias what 2 things do you look at to determine them?

Answer 13

Rate and Rhythm

Question 14

How do you know that an Arrhythmia is a sinus?

Answer 14

One P wave for every R wave

Question 15

How do you know if it is a Bradycardia?

Answer 15

HR less than 60 bpm is bradychardia

Question 16

How do you know if it is a tachycardia?

Answer 16

HR over 100 BPM is tachycardia

Question 17

What is a symptom of Bradycardia? What drug could lead to Bradycardia?

Answer 17

Long PR interval

M2 agonist

Question 18

What state of the heart changes when you have really fast heart rates?

Answer 18

Diastole, when heart fills with blood.

Question 19

If you start shortening the amount of blood that fills the heart. Shortening Diastole. what is this?

Answer 19

Tachycardia

Question 20

What is worse, bradycardia or tachycardia?

Answer 20

Tachycardia, you could have another arrhythmia. Bradycardia you just pass out.

Question 21

Rapid, regular atrial depolarizations
Sawtooth pattern
Normal QRS as AV node is refractory for most atrial depolarizations.

Answer 21

Atrial flutter

Question 22

No coordination of atrial depolarization. Irregular QRS, AV node will fire as soon as it is no longer refractory.

Answer 22

Atrial fibrilation

Question 23

Atrial fibrilation, what do you always make sure the patient is taking?

Answer 23

Anti-coagulant, blood thinner.

Question 24

What are the conduction blocks we need to know? (SPOT THESE ON A TEST)

Answer 24

1st degree- prolonged PR interval (>.2s)
-due to increased AV node delay
2nd degree blocks- not all p-waves are conducted via AV Node
-Mobitz Type I- PR interval gets progressively longer until a beat is dropped
-Mobitz Type II- PR interval is set, but still drop beats
3rd degree- No conduction via AV node between atria and ventricles
-Both P-waves and QRS have regular rhythm but are not in sync
-QRS can be wide

Question 25

Whats the diff between sinus tachycardia and ventricular tachycardia?

Answer 25

you are missing P waves in V tach (ischemic event, can lead to fibrillation)
-Vtach is very rapid contractions (probably not ejecting a whole lot of blood because it is going so fast)

Question 26

Disruption of oxygen delivery

Answer 26

Ischemia

Question 27

Whats going to start an ischemic event?

Answer 27

plaque in artery. Any interruption in delivery of oxygen.

Question 28

What is Peaked T-waves, transitioning into inverted T-waves?

Answer 28

Early Ischemia… or local Hyperkalemia outside of ventricles
(T-wave= repolarization of ventricles)

Question 29

What does ST-segment elevation do?

Answer 29

ST segment is rapidly approaching permanent dead tissue.

Question 30

If you see Q-waves it is a sign of what?

Answer 30

Permanent damage or an old infarct

Question 31

Early ischemia looks a lot like what else?

Answer 31

Hyperkalemia

Question 32

Hyperkalemia has what characteristics on an ECG?

Answer 32

Peaked T-waves
Prolonged PR interval
Widened QRS, merges with T wave

Question 33

Hypokalemia has what characteristics on an ECG?

Answer 33

• ST depression
• Flattened T-wave and long QT
• U wave

Question 34

Know rate, Rhythm, Axis, what axis shift represents, if evidence of ischemia, predict how old ischemia is… Hypo and hyperkalemia levels and what they do…

Answer 34

RATE
RHYTHM
AXIS
INFARCT

Question 35

What could result in widened QRS complex?

Answer 35

Hyperkalemia 
Sodium channel (Nav)blocker