Image Based Question-67099

Correct Answer » A Explanation

Ans: A. Hyperkalemia

This ECG image displays many of the features of hyperkalaemia:

• Prolonged PR interval.
• Broad, bizarre QRS complexes — these merge with both the preceding P wave and subsequent T wave.
• Peaked T waves.

Hyperkalemia

• Potassium is vital for regulating the normal electrical activity of the heart.
• Increased extracellular potassium reduces myocardial excitability, with depression of both pacemaking and conducting tissues.
• Progressively worsening hyperkalaemia leads to suppression of impulse generation by the SA node and reduced conduction by the AV node and His-Purkinje system, resulting in bradycardia and conduction blocks and ultimately cardiac arrest.

Classification

• Hyperkalaemia is defined as a potassium level > 5.5 mEq/L
• Moderate hyperkalaemia is a serum potassium > 6.0 mEq/L
• Severe hyperkalaemia is a serum potassium > 7.0 mE/L

Effects of Hyperkalemia on ECG

Serum potassium > 5.5 mEq/L is associated with repolarization abnormalities:

• Peaked T waves (usually the earliest sign of hyperkalaemia)
• Serum potassium > 6.5 mEq/L is associated with progressive paralysis of the atria:
• P wave widens and flattens
• PR segment lengthens
• P waves eventually disappear

Serum potassium > 7.0 mEq/L is associated with conduction abnormalities and bradycardia:

• Prolonged QRS interval with bizarre QRS morphology
• High-grade AV block with slow junctional and ventricular escape rhythms
• Any kind of conduction block (bundle branch blocks, fascicular blocks)
• Sinus bradycardia or slow AF
• Development of a sine wave appearance (a pre-terminal rhythm)

Serum potassium level of > 9.0 mEq/L causes cardiac arrest due to:

• Asystole
• Ventricular fibrillation