Intracoronary ST-segment alternans during coronary balloon angioplasty.

ST-segment alternans has been described in experimental coronary artery occlusion and in patients with variant angina. It is also seen during coronary angioplasty. This report describes a patient who on balloon inflation during coronary angioplasty demonstrated ST-segment alternans only on intracoronary electrocardiogram but did not on surface 12 lead electrocardiogram. Hemodynamic pulsus alternans of the aortic pressure tracing was not observed during electrical alternans.