morphology template
A stored electrogram pattern used by ICDs to distinguish between different types of cardiac rhythms.
Full Definition
A morphology template is a digitally stored reference pattern of cardiac electrical activity that serves as a baseline for rhythm discrimination in implantable cardioverter defibrillators. During device implantation or follow-up visits, templates are typically created from the patient's intrinsic ventricular conduction pattern (usually sinus rhythm) and stored in device memory. During subsequent arrhythmic episodes, the ICD compares incoming electrograms to these stored templates to help differentiate between ventricular tachycardia (which typically has a different morphology than the template) and supraventricular tachycardia with aberrant conduction (which may match the template more closely). This morphology discrimination helps reduce inappropriate shocks by improving the device's ability to distinguish between life-threatening ventricular arrhythmias requiring therapy and supraventricular arrhythmias that should not be treated with defibrillation.
Usage
Usage note: Often simply called 'template' in device programming interfaces; specify 'morphology' for clarity.
In Context
- "The morphology template was updated to improve discrimination after the patient experienced inappropriate shocks during atrial fibrillation." — Device programming note
- "VT was correctly identified based on poor correlation with the stored morphology template despite similar rates." — Arrhythmia episode analysis