Pacemakers & ICDs

A patient with a pacemaker reports hiccups and muscle twitching near the device — is this a benign complaint or a sign the lead has migrated? Knowing pacemaker and ICD nursing care separates safe practice from missed complications.

Pacemakers deliver electrical impulses to maintain a minimum heart rate when the heart's conduction system fails. An ICD (implantable cardioverter-defibrillator) does everything a pacemaker does plus monitors for lethal ventricular dysrhythmias and delivers a shock to terminate them. On telemetry, a functioning pacemaker produces a visible pacing spike immediately before the captured complex — an atrial spike before the P wave, a ventricular spike before the QRS, or both in dual-chamber devices. Failure to capture means the spike fires but no complex follows; failure to sense means the device doesn't detect native beats and fires inappropriately, risking competition with the heart's own rhythm. After implantation, the arm on the insertion side is restricted from reaching above shoulder level for 4–6 weeks to prevent lead displacement. Monitor the insertion site for hematoma, infection, and signs of pneumothorax (sudden dyspnea, absent breath sounds) since subclavian access is common. Patients must avoid MRI (unless the device is MRI-conditional and cleared), stay at least 6 inches from strong magnets, and carry their device ID card. For ICD patients, teach them that a shock feels like a chest kick; if they receive multiple shocks in a row, call 911.

Key Distinctions

Failure to capture (spike present, no QRS) versus failure to sense (device ignores native beats, fires at wrong times) — these are opposite malfunctions with different interventions. A pacemaker only paces; an ICD paces AND defibrillates — students mix up which device treats bradycardia alone versus lethal tachyarrhythmias. Placing a magnet over an ICD disables shock therapy; over a pacemaker it switches to asynchronous pacing — these are not the same response.

Clinical Pearl

Spike then capture — that's the rhythm you want. Spike with nothing after it means the lead isn't talking to the heart, and that's an emergency call to the provider.