Cardiac Implantable Electronic Devices

Device types

• Pacemaker — treats bradycardia (see Bradyarrhythmias).
• Implantable cardioverter-defibrillator (ICD) — treats ventricular arrhythmias (see VT/VF).
• Cardiac resynchronisation therapy (CRT) — a specialised pacemaker stimulating the left ventricle in heart failure with reduced ejection fraction; may include a defibrillator (CRT-D) or pacemaker only (CRT-P).
• Implantable loop recorder (ILR) — monitors/diagnoses rhythm disorders when non-invasive methods (e.g. Holter monitoring) have been exhausted, such as infrequent, undifferentiated syncope.

Indications

Permanent pacemaker (regardless of symptoms): Mobitz II second-degree, high-grade, or third-degree AV block. Symptomatic patients: sinus node dysfunction; AF with bradycardia; bradycardia from required medical therapy (e.g. beta-blockers in heart failure). Special circumstances: Mobitz I second-degree or marked first-degree AV block; refractory vasovagal syncope; long QT syndrome. Sinus bradycardia is defined as < 50bpm, but slower asymptomatic rates may not require pacing.

ICD — secondary prevention: survived cardiac arrest; sustained VT > 30 seconds. Primary prevention: LVEF < 35% (NYHA II–III) or < 30% (NYHA I), on guideline-directed medical therapy, prognosis > 12 months, and at least 40 days post-MI/90 days post-PCI or CABG. Special populations (per disease-specific guidelines): hypertrophic cardiomyopathy, long QT syndrome, Brugada syndrome, arrhythmogenic right ventricular cardiomyopathy.

Recent technology advances

• MRI-conditional/compatible devices: most contemporary CIEDs and leads are now labelled “MRI conditional,” reversing the old blanket contraindication — an estimated 50–75% of device patients will need an MRI over their lifetime. Safe scanning requires predefined safety checks and a management plan (radiologist + cardiologist discussion). Patients with older non-conditional devices or abandoned leads can sometimes still be scanned safely at expert centres with electrophysiology support if the MRI is genuinely essential.
• Remote monitoring: now standard for most CIEDs — device data transmits from home (via a bedside monitor or a smartphone app over Bluetooth/cellular/WiFi) to the device clinic, without needing an in-person visit. Detects dangerous arrhythmias early (reducing mortality and painful inappropriate shocks) and preclinical heart failure episodes, and reduces the frequency of routine in-clinic checks.
• Leadless pacemakers and subcutaneous ICDs — alternatives to conventional transvenous leads, reducing lead-related infection and vascular complications.
• Conduction system pacing — a newer technique capturing the heart’s native conduction system for more physiological cardiac activation, used for both standard pacing and heart failure treatment/prevention.

Practical points for general practice

• Driving: restrictions apply after new implantation or a significant arrhythmic event (per Austroads medical standards) — check current requirements with the patient’s cardiologist/device clinic rather than assuming a fixed period, as this varies by device indication (pacemaker vs ICD) and by private/commercial licence.
• Magnet application (over an ICD, to suspend shock therapy — e.g. during surgery with electrocautery) and end-of-life device deactivation are both specialist/ device-clinic-led decisions — involve the patient’s cardiology team or device clinic rather than managing these independently in general practice.
• Refer any concerns about device malfunction, recurrent shocks, or wound complications back to the implanting service/device clinic.