Question

Discuss the value of looking for signs of all types of electrolyte imbalances on the 12-Lead (not just hyperkalemia).

Answer 1

Imbalance between intracellular and extracellular electrolyte concentration may alter cardiac action potential. These changes in the rhythm of heart can be seen on ECG.

1. ECG changes due to sodium imbalance: no change in ECG due to no effect on cardiace rhythm

2. ECG changes due to hypercalcemia : increased calcium concentration can cause bradycardia, AV block, sinus node dysfunction, ventricular tachycardia and ventricular fibrillations. ECG changes include short QT interval, lengthened QRS interval, Increased QRS amplitude, reduced amplitude of T wave, Osborn-like waves,ST segment elevation is seen sometimes in leads V1–V2.

3. ECG changes due to hypocalcemia: can result in AV block, SA block, Sinus bradycardia, Ventricular fibrillation. ECG changes include short QRS duration and increased QT interval.

4. ECG changes due to hyperkalemia : slowing of electrical impulse in heart.

ECG changed include pointed T wave, wider P wave, prolonged PR interval, ST segment elevation may occur in V1–V3.

5. ECG changes due to hypokalemia : wider T-waves with lower amplitude, T-wave inversion,  ST segment depression, P-wave amplitude increases, increased P-wave duration and PR interval, U-waves become visible which are best seen in leads V2–V3.

6. ECG changes due to magnesium imbalance: increased magnesium concentration may cause atrioventricular and intraventricular conduction impairments.

Decreased magnesium concentration can cause supra-ventricular and ventricular tachyarrhythmias.