L7: Drug and Electrolyte effects

Question 1

Benign Early Repolarization

Answer 1

J point notching

T wave asymmetry, concordance with QRS
Upsloping ST segment, minimal elevation,

Question 2

Diffuse ST elevation that returns to baseline without T wave inversion, no Q waves

Answer 2

Pericarditis

Question 3

Low voltage seen on EKG

Answer 3

Pericarditis with effusion

Question 4

Changing amplitude of the QRS complexes

Answer 4

Electrical alternans

Large pericardial effusion

Question 5

Small Pulmonary embolism on ECG

Answer 5

Sinus tachycardia

Question 6

S1 Q3 T3

Answer 6

Large PE
Lead I→ large S
Lead III→ deep Q wave
Lead III→ inverted T

Question 7

What else might be seen with a PE?

Answer 7

• Right axis deviation
• Signs of RAE
• New RBBB may be seen acutely
• T waves may be inverted in precordial leads (V1-4)
• Persistence of lateral S-waves (even without complete RBBB)
• Tachyarrhythmias!

Question 8

V1-V3 in PE

Answer 8

RBBB +/- T wave inversions in V1-4

Question 9

PEs can cause

Answer 9

acute right heart failure

Question 10

QTI < ___ = Short QT syndrome

Answer 10

QTI < .35 sec

Question 11

Long QTc

Answer 11

Women > .46 s

Men > . 44 s

Question 12

At what QTc does the risk of Torsades de Pointes occur?

Answer 12

QTc > .5

Question 13

Tall peaked T waves

Answer 13

Hyperkalemia 5.5-6.5

Question 14

Tall peaked T waves
Flattened P waves
Wide QRS

Answer 14

Hyperkalemia >6.5

Question 15

Sine-wave pattern

Answer 15

Merging of S and T waves

Hyperkalemia > 7.0

Question 16

U waves

Answer 16

hypokalemia

Question 17

Moderately low potassium

Answer 17

T wave flattens, U wave

Question 18

Extremely low potassium

Answer 18

very prominent U wave

Question 19

Hypercalcemia

Answer 19

Decreased automaticity with slowed conduction
Shorter refractory period

Increased PR interval and QRS interval
Bundle branch blocks and AV block
Shorter ST segment and shorter QT interval

Question 20

Electrolyte effects that prolong QT interval

Answer 20

Hypokalemia
Hypocalcemia
Hypomagnesemia

Question 21

Therapeutic digoxin levels ECG (don’t d/c)

Answer 21

Shortened QT interval
Flattened T waves
Asymmetric ST depression and T wave inversion in leads with tall R waves
Gradual downslope of ST

Question 22

Therapeutic digoxin levels are ____ ng/ml

Answer 22

> 8-2.0 ng/ml

Question 23

Toxic digoxin levels are ____ ng/ml

Answer 23

> 2.4 ng/ml

Question 24

3 situations where toxic digoxin levels are more likely

Answer 24

Renal disease (renal excretion)
hypokalemia (exacerbates)
aging

Question 25

Most characteristic sign of digoxin toxicity

Answer 25

PAT with 2nd degree AV block (2:1)

Question 26

Other possible signs of digoxin toxicity

Answer 26

Slows conduction through AV node→ 1st/2nd/3rd degree block

Any tachydysrhythmia possible (atach, VT, VF

Question 27

Discontinue a drug if the QTI increases by more than ___ or _____-

Answer 27

> 35%

QTc > .5 sec

Question 28

Prolonged QTI:
Narrow QR
Widened RS
+/- long PRI hidden beneath T

Answer 28

TCA overdose

Question 29

All intervals are prolonged + Osborn waves

Answer 29

Hypothermia

Question 30

Osborn waves

Answer 30

ST segment elevation + abrupt ascent at J point, plunge back to baseline
Seen in hypothermia

Question 31

Brugada syndrome

Answer 31

Rare inherited autosomal
dominant genetic defect
Family history of sudden cardiac death
Personal history of serious heart rhythm problems
Personal history of severe fainting spells
More common in younger patients (30’s)
More prevalent in Asian populations
ST segment elevation abnormalities

Question 32

2 things that decrease QTI

Answer 32

Hypercalcemia

Digoxin

Question 33

Things the increase QTI

Answer 33

Hypocalcemia (and other low electorlytes)
Antiarrhythmics
TCAs
Phenothiazines
Macrolides