exercise-induced QRS alternans
Beat-to-beat variation in QRS morphology or amplitude that appears during exercise, potentially indicating electrical instability.
Full Definition
Exercise-induced QRS alternans is an electrocardiographic phenomenon characterized by alternating QRS complex morphology or amplitude on a beat-to-beat basis during exercise stress testing. This finding may indicate underlying electrical instability, ischemia, or increased risk for ventricular arrhythmias during physical exertion. Unlike microvolt T-wave alternans, QRS alternans involves visible changes in the QRS complex and may be associated with structural heart disease or ion channel abnormalities that become apparent during exercise stress.
Usage
Usage note: Distinguish from T-wave alternans and from normal QRS variations due to respiratory or postural changes.
In Context
- "Exercise testing revealed concerning QRS alternans at submaximal workloads." — Cardiology consultation report
- "The presence of exercise-induced QRS alternans prompted further cardiac evaluation." — Risk stratification assessment