L7: Drug and Electrolyte effects Flashcards
Benign Early Repolarization
J point notching
T wave asymmetry, concordance with QRS
Upsloping ST segment, minimal elevation,
Diffuse ST elevation that returns to baseline without T wave inversion, no Q waves
Pericarditis
Low voltage seen on EKG
Pericarditis with effusion
Changing amplitude of the QRS complexes
Electrical alternans
Large pericardial effusion
Small Pulmonary embolism on ECG
Sinus tachycardia
S1 Q3 T3
Large PE
Lead I→ large S
Lead III→ deep Q wave
Lead III→ inverted T
What else might be seen with a PE?
- 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!
V1-V3 in PE
RBBB +/- T wave inversions in V1-4
PEs can cause
acute right heart failure
QTI < ___ = Short QT syndrome
QTI < .35 sec
Long QTc
Women > .46 s
Men > . 44 s
At what QTc does the risk of Torsades de Pointes occur?
QTc > .5
Tall peaked T waves
Hyperkalemia 5.5-6.5
Tall peaked T waves
Flattened P waves
Wide QRS
Hyperkalemia >6.5
Sine-wave pattern
Merging of S and T waves
Hyperkalemia > 7.0
U waves
hypokalemia
Moderately low potassium
T wave flattens, U wave
Extremely low potassium
very prominent U wave
Hypercalcemia
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
Electrolyte effects that prolong QT interval
Hypokalemia
Hypocalcemia
Hypomagnesemia
Therapeutic digoxin levels ECG (don’t d/c)
Shortened QT interval
Flattened T waves
Asymmetric ST depression and T wave inversion in leads with tall R waves
Gradual downslope of ST
Therapeutic digoxin levels are ____ ng/ml
> 8-2.0 ng/ml
Toxic digoxin levels are ____ ng/ml
> 2.4 ng/ml
3 situations where toxic digoxin levels are more likely
Renal disease (renal excretion)
hypokalemia (exacerbates)
aging
Most characteristic sign of digoxin toxicity
PAT with 2nd degree AV block (2:1)
Other possible signs of digoxin toxicity
Slows conduction through AV node→ 1st/2nd/3rd degree block
Any tachydysrhythmia possible (atach, VT, VF
Discontinue a drug if the QTI increases by more than ___ or _____-
> 35%
QTc > .5 sec
Prolonged QTI:
Narrow QR
Widened RS
+/- long PRI hidden beneath T
TCA overdose
All intervals are prolonged + Osborn waves
Hypothermia
Osborn waves
ST segment elevation + abrupt ascent at J point, plunge back to baseline
Seen in hypothermia
Brugada syndrome
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
2 things that decrease QTI
Hypercalcemia
Digoxin
Things the increase QTI
Hypocalcemia (and other low electorlytes) Antiarrhythmics TCAs Phenothiazines Macrolides
