QRST alternans

A 60 yo with a h/o of DM and chronic kidney disease is admitted due to respiratory failure and shock. This ECG was noted while being monitored?

Figure 1

This was refered to cardiology service because of QRS alternans. Cardiac tamponade as a cause of the QRS alternans was ruled-out by echocardiography.

On the 12 L, there is sinus rhtyhm. On the QRS with normal duration, there is diffuse flattening of the ST segment and the extra distortion could be U waves. Seeing that, the QT is prolonged. On the alternating wide QRS complexes, the PR interval are short and NOT CONSTANT. The T waves are pronounced and inverted. Thus this is thought to be fused PVC's in bigeminal pattern creating pseudo-alternans. 

This patient was noted to have hypokalemia. It was replaced and the bigeminal pattern was resolved.

#299