EKG Quiz

Question 1

What two leads should you consult to assess for RBBB or LBBB? How can you differentiate between the two?

Answer 1

look at V1 and V6
RBBB: V1 will have “rabbit ears”
LBBB: V6 will show abnormally wide QRS with a notched R wave

Question 2

How can you assess for first degree heart block on an EKG?

Answer 2

PR interval >0.20 seconds and is constant from beat to beat

Question 3

How can you assess for second degree AV block-Mobitz Type I on an EKG?

Answer 3

a progressive increase in the PR interval from beat to beat until finally the QRS complex, and a beat, is dropped.

Question 4

What is another name for second degree AV block-Mobitz I?

Answer 4

Wenckebach

Question 5

How can you assess for second degree AV block-Mobitz II?

Answer 5

a sudden appearance of a nonconducted P wave; p waves are normal but some are not followed by QRS complexes; PR and RR intervals are constant.

Question 6

Which is more serious…. Wenckebach or Mobitz Type II?

Answer 6

Type II

Question 7

How can you assess for third degree heart block on an EKG?

Answer 7

independent (dissociated) atrial (P) and ventricular (QRS) activity; the P waves have no fixed relationship to the QRS complexes.

Question 8

What is seen during inspiration with sinus arrhythmia?

Answer 8

an increase in HR

Question 9

What is the reflex that is seen during sinus arrhythmia and what is occurring?

Answer 9

bainbridge reflex–> HR increases during inspiration b\c intrathoracic pressure falls…. so, IVC widens and venous blood pressure falls…. increasing venous return to the right atrium…. right atrium stretches and reflexively HR increases

Question 10

How can you spot an atrial premature contraction?

Answer 10

The p wave is normally different than the sinus P waves and is conducted slightly earlier. Some may have a QRS follow, and some may not.

Question 11

What happens if the p wave for an APC occurs too early?

Answer 11

it may fall on the T wave (when the ventricles are in the absolute refractory period) and thus be non-conducted.

Question 12

What does subendocardial ischemia mean?

Answer 12

occurring beneath the endocardium or between endocardium and myocardium

Question 13

What does transmural ischemia mean?

Answer 13

occurring across the entire wall

Question 14

What is seen during subendocardial ischemia and injury in the ST segment?

Answer 14

depression of > 1 mm

Question 15

What is seen in the ST segment during transmural ischemia and injury?

Answer 15

transmural ischemia: symmetrically inverted T waves

transmural injury: ST segment elevation > 1mm

Question 16

Think about what is happening in the action potential of myocardial cells during contraction and the corresponding EKG tracing. Ventricular depolarization occurs from Q all the way until ventricular repolarization in the T wave. So in regards to calcium, what is seen on the EKG tracing with hypocalcemia and hypercalcemia?

Answer 16

hypocalcemia: prolonged QT segment
hypercalcemia: shortened QT segment
QT is normally around ~2 big boxes (0.4sec)

Question 17

What does the QT interval represent?

Answer 17

the duration of the plateau phase (calcium)

Question 18

What phase of the myocardial action potential represents ventricular depolarization?

Answer 18

phase 0 (Na influx)

Question 19

What phase of the myocardial action potential represents ventricular repolarization?

Answer 19

phase 3 (K efflux)

Question 20

What can be seen on an EKG in the presence of hyperkalemia?

Answer 20

peaked T waves (this is phase 3 when K+ efflux is occuring, so there is MORE K+ than usual= peaked T)

Question 21

What can be seen on an EKG in the presence of hypokalemia?

Answer 21

U waves (not usually seen)

Question 22

What HR is seen with paroxysmal atrial tachycardia (PAT)?

Answer 22

150-250

Question 23

How do you treat PAT?

Answer 23

1) vagal maneuvers (carotid massage)
2) verapamil 5-10mg terminates AV nodal reentry (successful in ~90% of cases–> drug of choice)
3) esmolol 1mg/kg bolus and 50-200mcg/kg/min infusion shown effective in treating postop SVT’s
4) propanolol in 0.5mg IV bolus doses
5) edrophonium (tensilon) in 5-10mg IV bolus doses
6) phenylephrine 100mcg bolus doses (if pt is hypotensive–> in effort to increase BP and achieve a reflex vagal slowing of HR)
7) IV digitalization with one of the short acting digitalis preparations: ouabain (0.25-0.5mg IV) or digoxin (0.5-1.0mg IV)
8) rapid overdrive pacing in effort to capture ectopic focus
9) cardioversion with appropriate synchronization

Question 24

How do the P waves look with a PVC?

Answer 24

like nothing… there are none :)

Question 25

What are the treatments for PVC’s?

Answer 25

1st step: treat underlying abnormalities such as hypokalemia or low PaO2

2nd: lidocaine is usually the treatment of choice (initial bolus of 1.5mg/kg IV)
* recurrent PVCs can be treated with lidocaine infusion of 1-4mg/min
* additional therapy can include esmolol, propanolol, procainamide, quinidine, verapamil, disopyramide, atropine, or overdrive pacing

Question 26

What two drugs should be avoided in WPW, and why?

Answer 26

digoxin and verapamil–> increases conduction through the accessory bypass tract (bundle of Kent) and decreases AV node conduction–> v-fib can occur

Question 27

What is the hallmark EKG finding for WPW?

Answer 27

p waves normal; PR interval short (<100bpm

Question 28

What are the best leads to detect posterior and inferior wall infarction? name the coronary artery that supplies it.

Answer 28

II, III, aVF–> right (RCA)

Question 29

What are the best leads to detect septum and anterior wall infarction? name the coronary artery that supplies it.

Answer 29

V2-V5–> left anterior descending (LAD)

Question 30

What are the best leads to detect lateral wall infarction? name the coronary artery that supplies it.

Answer 30

I, aVL, V4-V6–> left circumflex

Question 31

What is the best overall lead for an MI?

Answer 31

V5