Cardiac Devices · Module 2 of 7

ICD Fundamentals

Technologist focusedInteractive lessonConceptual education

Understand how ICDs detect ventricular tachyarrhythmias and conceptually use ATP and shock therapy.

Learning objectives

PurposeUnderstand the distinction between pacing and defibrillation functions.
DetectionRecognize that ICDs classify ventricular rhythm using programmed detection logic.
TherapyKnow the conceptual roles of ATP and shock therapy.

What makes an ICD different?

An implantable cardioverter-defibrillator can provide bradycardia pacing while also detecting selected ventricular tachyarrhythmias and delivering programmed therapies. Depending on device type and programming, therapy may include antitachycardia pacing (ATP) and/or high-energy shock.

DETECTEvaluate ventricular events
CLASSIFYApply programmed criteria
THERAPYATP / shock when indicated
STORERecord episode data

Detection is not simply “heart rate is high”

Modern ICDs use manufacturer- and programming-specific detection zones, timing/counting criteria and discrimination features. Stored electrograms are essential for understanding why an episode was classified and treated.

Tech perspective

An ICD reports a treated episode

The important question is not only “Was there a shock?” Review the episode context with the qualified device team: stored electrograms, detection classification, therapy sequence and the rhythm before, during and after therapy.

What is ATP?

Educational scope: Device programming, implant decisions, therapy changes, alerts and patient management require appropriately credentialed clinicians, institutional protocols, and current manufacturer instructions.
Lesson progress

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Pacemaker Fundamentals