Week 5- Electrolytes and ECG Changes

Question 1

Where are electrolytes found?

Answer 1

• Found in extracellular and intracellular fluid of most cells

Question 2

What are the most important electrolytes?

Answer 2

• sodium, potassium, and calcium

Question 3

What are the 2 main electrolytes that cause diagnostic and recognizable changes on ECG?

Answer 3

• Potassium and calcium

Question 4

What are hyperkalemia and its effects?

Answer 4

• High potassium level
• Hyperkalemia is most dangerous of all electrolyte changes, can kill in seconds, and prevents response to drugs used in resuscitation
• It causes change in appearance of QRS complex, any and all arrhythmias

Question 5

What are the main changes in hyperkalemia?

Answer 5

• T wave abnormalities, especially tall and peaked T waves
• P waves missing or decrease amplitude
• ST segment changes simulating an injury pattern
• Cardiac arrhythmias, any and all varieties (any wide rhythm could be due to hyperkalemia)

Question 6

Spectrum of hyperkalemia

Answer 6

• Hyperkalemia occurs across a spectrum:
  
  • T waves becomes a tall and sharp
  • All intervals begin to widen and decrease in amplitude
  • P waves loses amplitude until its not seen
  • As K+ levels rise, whole morphology of complexes is lost
  • Finally, a straight line

Question 7

T Wave Abnormalities

Answer 7

• T waves abnormalities are the first changes seen in a patient developing hyperkalemia
• Occurs when K+ levels exceeds 5.5 mEg/L (normal lvls= 3.5-5.0 mEq/L)
• Most famous T wave change is tall, peaked, narrow T
• At 5.5 mEq/L, T wave are tall, peaked, and narrow, normal or slightly prolonged QT
• As K+ increases, T waves and PR, QRS and QT interval widen. Amplitude becomes smaller
• Affect appearance of T waves

Question 8

P Waves and Hyperkalemia

Answer 8

• As K+ level increases above 7.0 mEq/L, PR interval increases
• P wave amplitude decreases
• Eventually, you won’t see any P waves
• As K+ levels increase, atrial myocardial cells stop depolarizing
• SA node and conduction system of the atria continue to function, but myocardial cell will not

Question 9

What is hypokalemia?

Answer 9

• Changes on ECG aren’t very dramatic
• There are nonspecific changes:
  
  • Mild ST segment depression
  • Mild decrease amplitude of T wave
  • Minimal prolongation of QRS interval
  • Prominent U wave (small wave that occurs after T wave)

Question 10

Hypokalemia- differential diagnosis of U waves

Answer 10

• Hypokalemia
• Bradycardia
• Left ventricle hypertrophy
• Drug use: digoxin, antiarrhythmic
• Probability of developing an arrhythmia because of hypokalemia is low

Question 11

What is hypercalcemia?

Answer 11

• High calcium level
• Changes on ECG are also minimal: (shortening of ST segment, shortened QT interval, widened, flat T waves)
• Severe hypercalcemia can also mimic an acute MI
• Cardiac arrhythmia are rare

Question 12

What is hypocalcemia?

Answer 12

• Low calcium level
• Main ECG change is prolongation of ST segment that produces a lengthening of the QT interval
• Cardiac arrhythmia are rare (any QT prolongation has sanger to develop torsade de pointes, which can cause sudden death)