U waves

Question 1

U wave definition

Answer 1

small 0.5 mm deflection

same direction as T wave

Question 2

Normal U wave

Answer 2

same direction as T wave
size inversely proportional to HR
- increases as HR slows down
normal voltage < 25% of T wave
max normal amplitude= 1-2 mm

Question 3

Prominent U Wave

Answer 3

> 1-2 mm

> 25% height of T wave

Question 4

Prominent U wave DDx

Answer 4

severe Hypokalemia
Hypocalcaemia
Hypomagnesemia
Hypothermia
Raised Intracranial pressure
L Ventricular Hypertrophy
Hypertrophic cardiomyopathy

Question 5

Prominent U waves: secondary to DRUGS

Answer 5

Digoxin
Phenothiazine
Class Ia antiarrhythmic: quinidine/ procainamide
Class III antiarrhythmic: sotalol/ amiodarone

Question 6

Inverted U wave

Answer 6

inversion abnormal in lead with upright T wave

negative U highly specific for presence of heart dz

Question 7

Inverted U causes

Answer 7

Coronary artery disease
HTN
Valvular Heart Disease
Congenital Heart Disease
Cardiomyopathy
Hyperthyroidism

Question 8

Inverted U and Chest Pain

Answer 8

very specific Myocardial Ischaemia
earliest marker unstable angina evolving MI
predict ≥ 75% stenosis of LAD/ LMCA & LV dysfunction