EKG Intro

Question 1

What are some limitations of the EKG?

Answer 1

1. Is only a “snapshot.”
   (May not capture the cardiac problem at that exact moment)
2. Done at rest (Cannot reproduce CV issues that only occur during times of stress)
3. Represent electrical activity; not mechanical

Question 2

What happens to the myocytes during depolarization?

Answer 2

Myocyte membrane potential is made more NEGATIVELY CHARGED to physically CONTRACT the myocyte.

Question 3

What is the primary function of the myocyte?

Answer 3

To contract.

Contraction creates knock-on/chain reaction effect between myocytes

Question 4

What is the pacemaker of the heart?

What is it innervated by?

Answer 4

SA Node (Initiates electrical impulses and action potentials)

Can depol without stimulation (Automaticity), but also innervated by symp. and parasymp. (vagal) fibers

Question 5

Where do action potentials travel from the SA Node?

Answer 5

SA Node to Bachmann’s bundle to contract atria

SA Node to AV node, signal passed along to bundle of His –> Purkinje fibers –> Endocardium –> Vent. myocardium

Question 6

What does the P wave represent in an EKG?

Answer 6

Depolarization of atria.

Question 7

What is the quick estimation method for Rate of EKG’s?

Answer 7

300-150-100-75-60-50-(

or a NORMAL 6 sec strip x 10

Question 8

What is the Q wave

Answer 8

Intraseptal depolarization

Question 9

What does the QRS complex represent?

Answer 9

RAPID depolarization of both ventricles. (If prolonged start thinking LBBB/RBBB, LVH, Ventricular defects, HOCM, etc.)

Question 10

How can you determine if a PT is displaying LVH on an EKG?

Answer 10

The sum of the deep S wave in V1 and R wave in V5 = >35 mm

R wave in aVL > 11mm

Question 11

If Extreme/Marked RAD what should you consider?

Answer 11

1. Leads are reversed

2. Dextracardia

Question 12

What would indicate an infarct on an EKG?

Answer 12

Q wave >.04 sec (one small block
OR
Q wave (1/3rd amplitude or more of the QRS complex)

Question 13

Leads II, III, and aVF would indicate what kind of infarct?

Answer 13

Inferior wall: Leads II, III, and aVF

Question 14

Leads V1 and V2 would suggest what kind of infarct?

Answer 14

Anteroseptal wall defect: leads V1 and V2. (same as posterior wall MI)

Question 15

What leads would indicate a lateral wall defect? What about anterolateral?

Answer 15

Lateral wall MI: I and aVL

Anterolateral are V5 and V6

Question 16

What leads would indicate an anterior wall MI?

Answer 16

Anterior wall MI: V3 and V4

Question 17

What leads would indicate a posterior wall MI?

Answer 17

Posterior wall MI: V1 and V2. (same as anteroseptal wall) MI)

Question 18

What is a normal PR interval on an EKG?

Answer 18

0.12 to 0.20sec

Question 19

What is a normal QRS duration?

Answer 19

<0.12sec

Question 20

Chest pain with a new Left BBB on a PT what should you be concerned with?

Answer 20

MI. Order cardiac enzymes. You cannot interpret the EKG the same as you usually would though due to the LBBB (depolarization dysfunction)

Question 21

Where will a RBBB be visualized?

Answer 21

V1 and V2 with “Bunny ears” (b/c bunny ears are always right). If visualized look back at leads I and III for (Q1S3) for left anterior vasicular block/ a biphasic block

Question 22

What defining characteristic would clue you into a Mobitz 1 block (Wenckebach)?

Answer 22

Progressive elongation of PR intervals. Then a dropped beat (due to AV node inability to conduct stimulus)

Question 23

What is the rate of Atrial flutter and what is its general appearance on an EKG?

Answer 23

Sawtooth pattern

250-350bpm (THE FLUTTERS ARE 250 to 350 / FIBRILLATION is 350-450)

Question 24

Smooth, fine, sine waves appear on the EKG with very rapid intervals. The rate on the EKG is appx. 300bpm. What condition do you suspect?

Answer 24

V-flutter. Can also present as Torsades des Pointes with the “ribbon-like” appearance