ECG Electrolyte Disturbances

Question 1

How does low K alter the ECG?

Answer 1

Enhances automaticity

U waves, inc QT interval, flat or inverted T wave

Question 2

What does high K alter the ECG?

Answer 2

Widens QRS

Peaked T wave, wide QRS, inc PR interval, loss of P wave

Question 3

How does low calcium alter the ECG?

Answer 3

Prolongs QT interval 
Triggers arrhythmias (Torsades de pointes)

Question 4

How does high Ca alter the ECG?

Answer 4

Shortens QT interval

Short ST segment

Question 5

What is the etiology for hypokalemia?

Answer 5

Diuretics, metabolic alkalosis, high aldosterone, beta agonist overdose, diarrhea, renal loss

Question 6

What is the etiology for hyperkalemia?

Answer 6

Renal failure (insufficiency), metabolic acidosis, DKA, cell breakdown (hemolysis, Rhabdomylolysis)

Question 7

What is the etiology for hypercalcemia?

Answer 7

Hyperparathyroidism, malignancy, granulomatous disroders (TB, sarcoid), endocrine disorders (adrenal insufficiency, hyperthyroid)

Question 8

What changes does hypothermia cause?

Answer 8

J wave (Osborne wave) and bradycardia

Question 9

What changes does a pulmonary embolus cause?

Answer 9

Tachycardia 
Non specific ST changes 
S1Q3T3
T wave inversion V1-4 
Transient RBBB

Question 10

What is Wolff-Parkinson-White syndrome (WPW)?

Answer 10

Short PR interval 
Slurred upstroke (delta wave) of QRS complex 
Accessory AV conduction pathway (Bundle of Kent)

Question 11

What is Brugada syndrome?

Answer 11

RBBB with ST elevation in V1, 2 and 3

Susceptible to deadly arrhythmias

Question 12

What is Wellens syndrome?

Answer 12

Marked T wave inversion in V2 and V3

Anterior descending coronary stenosis

Question 13

What is long QT syndrome?

Answer 13

QT interval more than 1/3 of the cardiac cycle

Predisposed to ventricular arrhythmia