Sine wave pattern

The sine wave pattern is one of the manifestations of severe hyperkalemia. The sine wave pattern depicts worsening cardiac conduction delay caused by the elevated level of extracellular potassium. The morphology of this sinusoidal pattern on ECG results from the fusion of wide QRS complexes with T waves.

• Hyperkalemia induces electrophysiological changes in the myocardium leading to a series of findings on ECG. One of these ECG changes is a sine wave pattern which is a manifestation of severe hyperkalemia.
• Different levels of hyperkalemia cause different electrophysiological changes, the first sign of which is inverted T waves that are the result of accentuation of repolarization.
• Further increase in the potassium level causes a decrease in the velocity of cardiac conduction leading to PR interval prolongation, QRS widening, decrease in the amplitude of P waves and eventually absence of P waves. It is important to note that the absence of P waves does not depict sinus arrest at this level; in fact, the SA node continues to function without causing atrial contraction but rather causing only ventricular contraction. This rhythm is referred to as sinoventricular rythm.
• As the potassium level further increases, the delay in cardiac conduction worsens leading to further widening of the QRS complex which ends up in the fusion of the QRS complex with the T wave. The fusion of the QRS complex with the T wave in the absence of P wave is referred to as the sine wave pattern.^[1][2]

• Ventricular tachycardia
• SVT with bundle branch block

Shown below is an ECG demonstrating the sine wave pattern.

Copyleft image obtained courtesy of ECGpedia, http://en.ecgpedia.org/wiki/File:DVA0578.jpg

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