The "brain" of the device. Sealed titanium can housing battery (lithium-iodine, 7–10 yr lifespan), circuitry, and memory. Implanted in a subcutaneous pocket — usually left infraclavicular region.
Insulated wires connecting generator to myocardium. Transvenous leads pass via subclavian/cephalic vein. Tips anchored in right atrium (RA) and/or right ventricle (RV). Active fixation (screw) vs passive fixation (tines).
Defined by the NBG/NASPE code. Key parameters: rate (e.g. 60 bpm), output (mA), sensitivity (mV), AV delay (ms for dual-chamber). Rate-response adapts to activity via accelerometer.
Class I (Definite) Indications
- Complete (3rd degree) AV block — any rate, any symptoms
- Symptomatic 2nd degree AV block — Mobitz II (high risk of progression)
- Sick sinus syndrome (SSS) with symptomatic bradycardia
- Symptomatic sinus bradycardia not reversible by medication withdrawal
- Chronotropic incompetence — failure to increase HR with exertion
- Bi-fascicular or tri-fascicular block with syncope (PR interval prolonged + BBB)
| Feature | Pacemaker | ICD |
|---|---|---|
| Primary purpose | Prevent bradycardia | Terminate VT/VF |
| Energy delivered | 0.1–10 mA (pacing) | Up to 40 J (shock) |
| Has pacing function | Yes | Yes (backup pacing) |
| Has shock function | No | Yes (ATP + shock) |
| Main indication | Heart block, SSS, bradycardia | EF <35%, VT/VF survivors |
| Device size | Smaller (~25–35 g) | Larger (~80–100 g) |
| Pocket location | Left infraclavicular | Left infraclavicular (larger pocket) |
A 5-letter code describing pacemaker function. Positions I–IV are most clinically relevant.
| Position | I — Chamber Paced | II — Chamber Sensed | III — Response to Sensing | IV — Rate Response |
|---|---|---|---|---|
| Letters used | O, A, V, D | O, A, V, D | O, I, T, D | O, R |
| O | None | None | None | None |
| A | Atrium | Atrium | — | — |
| V | Ventricle | Ventricle | — | — |
| D | Dual (A+V) | Dual (A+V) | Dual (T+I) | — |
| I / T | — | — | Inhibited / Triggered | — |
| R | — | — | — | Rate-responsive |
Paces + senses both chambers; inhibited and triggered. Gold standard for AV block. Maintains AV synchrony.
Paces and senses ventricle only; inhibited by intrinsic beats. Used in AF with slow ventricular response. No AV synchrony.
Paces and senses atrium only; inhibited. Used in isolated SSS with intact AV conduction. Single-lead device.
Asynchronous ventricular pacing — fires at fixed rate regardless of intrinsic rhythm. Used in electromagnetic interference (EMI) environments or magnet application.
VVI with rate-response. Increases pacing rate during physical activity. Common in chronotropic incompetence with AF.
DDD with rate-response. Most physiological mode. Preferred for patients with AV block who are physically active.
| Feature | Temporary | Permanent |
|---|---|---|
| Types | Transvenous, transcutaneous, epicardial | Endocardial (transvenous), epicardial (surgical) |
| Duration | Hours to days (bridge therapy) | Years (device lifespan 7–15 yr) |
| Indications | Acute MI with heart block, drug overdose, post-cardiac surgery, haemodynamic instability | Chronic symptomatic bradycardia, permanent AV block, SSS |
| Insertion site | Femoral, internal jugular, subclavian (transvenous); chest pads (transcutaneous) | Cephalic or subclavian vein; pocket in pectoral region |
| Output | Transvenous: 2–20 mA; Transcutaneous: 20–200 mA | 0.25–5 V (much lower — lead in direct contact) |
| Pain | Transcutaneous is painful — requires sedation/analgesia | None after healing |
| Nursing risk | Lead displacement, infection, EMI sensitivity | Pocket infection, lead dislodgement (early), battery depletion |
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Continuous ECG monitoringVerify pacemaker spikes followed by appropriate P/QRS. Confirm programmed rate matches device card. Document baseline ECG strip.
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Vital signs every 15–30 min x 2 hr, then hourlyAssess BP, HR, SpO2, respiratory rate. Hypotension may indicate pneumothorax, haemothorax, or cardiac tamponade.
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Chest X-ray (CXR)Post-procedure CXR within 1 hour: confirm lead position (RA/RV), exclude pneumothorax, haemothorax, and lead perforation.
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Wound site inspectionObserve pocket for swelling, oozing, ecchymosis. Apply pressure dressing. Ensure haemostasis before transfer to ward.
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Arm restriction (implant side)Ipsilateral arm: no overhead movements, no abduction above shoulder level for 4–6 weeks. Use arm sling for comfort if needed first 24 hours.
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Neurological statusAssess consciousness, orientation — sedation reversal. Document pre-discharge GCS.
Normal Findings
- Mild swelling and bruising first 48–72 hr
- Slight tenderness at incision site
- Dressing intact, no breakthrough bleeding
Concerning Signs — Act Now
| Finding | Suspect | Action |
|---|---|---|
| Expanding haematoma | Pocket bleeding | Pressure, notify surgeon, check anticoagulation |
| Erythema + warmth + fever | Pocket infection | Blood cultures, antibiotics, device extraction may be needed |
| Skin thinning / erosion | Impending erosion | Urgent surgical review — risk of externalisation and systemic infection |
| Device rotating in pocket | Twiddler's syndrome | ECG for lead dislodgement, restrain manipulation, surgical revision |
| Wound dehiscence | Wound breakdown | Sterile cover, wound care nurse review, surgical closure |
- Device identification card given to patient (carry at all times)
- Programmed rate and mode explained to patient and family
- Arm restriction instructions provided in writing (implant side)
- Wound care instructions: keep dry 5–7 days, no submerging
- Emergency contacts: clinic number, 24-hr pacemaker hotline
- Follow-up appointment booked: 1 week wound check, 4–6 week device interrogation
- Driving restriction explained (see below)
- MRI compatibility status documented — provide card/letter
- Medication reconciliation: anticoagulation plan if applicable
- Patient education: symptoms to report (dizziness, syncope, palpitations, swelling)
Driving Restrictions (GCC/UAE)
| Device | Restriction Period |
|---|---|
| Pacemaker (new implant) | 1 week (private vehicle) — UAE RTA guidance |
| ICD (new implant) | 4 weeks minimum — UAE/Saudi Arabia guideline |
| ICD shock delivered | 6 months (appropriate shock) per SCFHS/DHA |
| Commercial/HGV licence | Disqualified with ICD — refer to licensing authority |
Return to Work & Activities
- Desk/office work: 1–2 weeks post-implant
- Manual labour / heavy lifting: 6–8 weeks (after wound healed, arm restriction lifted)
- Sports: avoid contact sports with device side impact; swimming after full healing
- Sexual activity: resume when comfortable, typically 1–2 weeks
MRI Considerations
- MRI-conditional devices: safe at 1.5 T under specific conditions — requires device card verification
- Non-MRI-conditional: MRI contraindicated — use alternative imaging (CT, ultrasound)
- Always inform MRI team of pacemaker prior to scan
- Device must be reprogrammed to asynchronous mode by trained staff before MRI
Pacemaker spikes are narrow, sharp vertical deflections on the ECG baseline. They precede the paced P-wave (atrial pacing) or paced QRS (ventricular pacing). Spike morphology depends on lead system and recording technique.
Definition: Pacemaker fires (spike visible) but myocardium does NOT respond — no P/QRS follows the spike.
Causes: Lead dislodgement, lead fracture, exit block (fibrosis), low battery, electrolyte disturbance (hyperkalaemia), increased pacing threshold.
Nursing Actions: Increase output (mA) on temporary pacer. Check lead connections. 12-lead ECG. Check electrolytes. Notify physician — may require lead revision or temporary transcutaneous pacing.
Definition: No pacing spike when rate falls below programmed lower rate — the device should fire but doesn't. Pauses seen on ECG.
Causes: Battery depletion, lead fracture/disconnection, oversensing (device inhibited by noise), electromagnetic interference.
Nursing Actions: Check all connections on external box. Apply magnet (converts to asynchronous — VOO). Remove EMI source. 12-lead ECG. Call for transcutaneous pacing backup. Urgent physician notification.
Definition: Pacemaker fails to detect intrinsic cardiac activity. Fires inappropriately — pacing spike occurs despite adequate intrinsic rhythm. Spike may fall on T-wave → R-on-T risk.
Causes: Sensitivity set too low (insensitive), lead dislodgement, lead fracture, electrolyte disturbance, fibrosis at lead tip.
Nursing Actions: Increase sensitivity setting (lower mV value = more sensitive). Check lead. Treat underlying electrolyte abnormality. Urgent review if R-on-T pattern — risk of VF.
Definition: Pacemaker senses non-cardiac signals (T-waves, myopotentials, EMI, crosstalk) and is inappropriately inhibited — device does not pace when it should.
Causes: Sensitivity set too high (too sensitive), T-wave sensing, myopotentials (muscle), EMI (electrocautery, MRI), crosstalk (A-channel sensed by V-channel).
Nursing Actions: Decrease sensitivity (increase mV threshold). Remove EMI source. Apply magnet to revert to asynchronous mode. Electrophysiology review.
Definition & Cause
Haemodynamic and symptomatic deterioration due to loss of AV synchrony — most commonly seen with VVI pacing when atria contract against closed AV valves.
Symptoms
- Fatigue, dyspnoea, dizziness, pre-syncope
- Pulsations in neck (cannon A-waves)
- Hypotension (drop in BP >20 mmHg with pacing vs intrinsic)
- Pulmonary congestion, reduced exercise tolerance
Nursing Management
- Document BP on intrinsic vs paced rhythmIf BP drops significantly with pacing → pacemaker syndrome confirmed
- Notify cardiologist / electrophysiologistMode reprogramming needed — upgrade VVI to DDD to restore AV synchrony
- Assess haemodynamics & oxygenationSpO2, BP, respiratory status. Supplemental oxygen if needed.
- Patient educationExplain symptoms, reassure device reprogramming will resolve symptoms
Clinical Features
Rapid pacing spikes on ECG at rates far exceeding programmed rate. Patient may be haemodynamically unstable, unconscious, or in VF.
Emergency Management
- Call for help — activate emergency teamEnsure defibrillator is at bedside
- Apply pacemaker magnet over deviceConverts to asynchronous (VOO) at fixed rate — stops runaway. Temporary measure only.
- If magnet unavailable: cut/disconnect leads (temporary pacemaker)For external temporary pacers only — never cut a permanent device lead without surgeon
- Defibrillate if VF/pulseless VT occursFollow ACLS. Place pads away from pulse generator (minimum 8 cm).
- Emergency electrophysiology consultationDevice will need reprogramming or emergent replacement
| Appropriate | Inappropriate | |
|---|---|---|
| Trigger | VT or VF detected | AF, SVT, T-wave oversensing, lead fracture |
| ECG | VT/VF before shock, normal sinus after | Sinus rhythm / SVT throughout |
| Patient experience | "Hard kick in the chest" during VT/VF | Shock during consciousness, normal activity |
| Action | Evaluate precipitant, antiarrhythmics, electrolytes | Device interrogation, reprogram detection, treat AF/SVT |
ICD shocks are traumatic. Patients frequently develop anxiety, depression, and PTSD. Nursing support is essential.
- Acknowledge the experience — validate fear and distress
- Explain why the shock occurred (appropriate vs inappropriate)
- Reassure patient the device is working correctly (if appropriate shock)
- Involve family members in education and support
- Refer to cardiac psychology / counselling service if available
- Provide ICD support group contacts (if available in GCC centre)
- Review driving restriction guidance after shock episode
- Document psychological assessment in nursing notes
- Apply pacing padsAnterior-posterior (preferred): anterior pad left precordium (V3–V5), posterior pad below left scapula. OR anterior-lateral: apex and right infraclavicular.
- Set parametersRate: 60–80 bpm. Output: Start at minimum, increase in 10 mA increments until electrical capture. Typical capture: 40–80 mA.
- Confirm electrical capturePacing spike followed by wide QRS on monitor. ECG artefact from muscle stimulation — look for capture beyond artefact.
- Confirm mechanical capturePalpate femoral pulse (radial may show artefact). SpO2 waveform with each paced beat. BP improvement.
- Analgesia & sedationTCP is painful. IV morphine/fentanyl + midazolam. Reassure patient. Monitor sedation level.
- Arrange transvenous pacingTCP is a bridge — arrange definitive transvenous temporary pacing or permanent device as soon as possible.
High-Risk EMI Sources
| Source | Risk | Precaution |
|---|---|---|
| MRI (non-compatible device) | Reed switch activation, heating, inhibition | Absolute contraindication unless MRI-conditional |
| Electrocautery / diathermy (OR) | Oversensing → inhibition or mode reversion | Use bipolar; place dispersive pad away from device; reprogram to asynchronous |
| TENS machine | Inhibition (sensing electrical pulses) | Avoid over pocket/leads; low-frequency TENS safer |
| Arc welding | Strong EMI field | Contraindicated within 60 cm of arc |
| Ablation (RF) | Sensing, mode changes | Device programmed off or asynchronous during procedure |
Low-Risk / Safe Sources
- Mobile phones — keep >15 cm from device; do not place in breast pocket
- Microwave ovens — modern ovens are shielded; safe for patient use
- Airport security scanners — walk through quickly; do not linger; carry device card
- Induction cooktops — keep distance >60 cm; use gas alternative if concerned
- Electric blankets — generally safe; avoid direct contact over device site
- Dental drills — safe unless using electrosurgery unit
Primary Prevention Indications
- EF ≤35% despite optimal medical therapy (≥3 months)
- NYHA Class II–III heart failure on optimal therapy
- Non-ischaemic cardiomyopathy with EF ≤35%
- Post-MI (≥40 days) with EF ≤30%
Secondary Prevention Indications
- Survivors of VF cardiac arrest (not due to reversible cause)
- Sustained VT with haemodynamic compromise
- Spontaneous sustained VT with structural heart disease
ICD Therapies
| Therapy | Description | Energy |
|---|---|---|
| ATP (Anti-Tachycardia Pacing) | Burst pacing to terminate VT without shock — painless | 0 J (pacing) |
| Low-energy cardioversion | Synchronised shock for VT | 0.5–5 J |
| Defibrillation | High-energy shock for VF or VT not terminated by ATP | 15–40 J |
| Backup pacing | Post-shock bradycardia support | Pacing mA |
Cardiac Resynchronisation Therapy — Indications
- EF ≤35% + NYHA Class II–IV heart failure
- QRS duration ≥150 ms (strongest evidence)
- LBBB morphology (greatest benefit)
- Sinus rhythm (or permanent AF with high pacing burden)
Biventricular pacemaker only — no shock therapy. Three leads: RA, RV, LV (via coronary sinus). Resynchronises ventricular contraction. For patients not requiring ICD.
Biventricular pacemaker PLUS ICD capability. Four functions: A-pacing, RV-pacing, LV-pacing (CRT), and defibrillation. For HF patients who also meet ICD criteria.
- Informed consent obtained — patient understands shocks, restrictions
- Baseline 12-lead ECG documented
- Echocardiogram confirming EF ≤35%
- Electrophysiology study completed (if indicated)
- Blood group and crossmatch available
- INR/anticoagulation bridged per protocol
- Allergy check: iodine, latex, antibiotics
- Fasting confirmed (6 hours food, 2 hours clear fluids)
- IV access (large bore) — non-dominant arm preferred
- Prophylactic antibiotics given within 30 min of incision
- Skin preparation: shave if required, chlorhexidine wash
- Baseline renal function (contrast may be used)
- Patient briefed on same-day discharge protocol if applicable
- Driving restriction explained and documented
- Next of kin contact confirmed
- Pacemaker-dependent status noted for emergency planning
Electromagnetic Precautions
- Keep mobile phone >15 cm from device — use opposite ear
- Inform airport security — carry ICD card; request hand search if preferred
- Avoid anti-theft security gates — walk through quickly, do not linger
- Avoid strong magnets (industrial, MRI without clearance)
- Safe: microwave ovens, computers, TV, electric razors, hairdryers
Physical Activity
- Avoid contact sports that could impact device pocket
- Swimming allowed after wound healing (~4–6 weeks)
- Cardiac rehabilitation recommended for HF/ICD patients
- No overhead arm movements for 4–6 weeks post-implant
What to Do If Shocked
- Single shock, feel wellSit or lie down. Rest. Contact clinic same day to report shock. Clinic will interrogate device remotely or in person.
- Multiple shocks or feel unwellCall emergency services (999/112) immediately. Do not drive. Go to nearest emergency department.
- Bystander safetyICD shock is NOT dangerous to bystanders. Touching patient during shock is safe — no risk of electrocution. CPR if patient unresponsive.
| Code | Full Name | Chambers | Clinical Use | AV Synchrony |
|---|---|---|---|---|
| DDD | Dual-Dual-Dual | A + V paced & sensed | Complete AV block, SSS — gold standard | Yes |
| DDDR | Dual-Dual-Dual-Rate | A + V + rate-adaptive | Active patients with AV block | Yes |
| VVI | Vent-Vent-Inhibited | V only | AF with slow ventricular response | No |
| VVIR | Vent-Vent-Inhibited-Rate | V + rate-adaptive | AF + chronotropic incompetence | No |
| AAI | Atrial-Atrial-Inhibited | A only | SSS with intact AV node | Intrinsic |
| VOO | Vent-None-None | V asynchronous | EMI present, magnet mode, testing | No |
| DOO | Dual-None-None | A + V asynchronous | Magnet application in DDD device | Fixed |
| ECG Finding | Diagnosis | First Action |
|---|---|---|
| Spike present, NO QRS follows | Failure to Capture | Increase output (mA); check lead |
| No spike when HR < set rate | Failure to Pace | Check connections; apply magnet |
| Spike falls on T-wave (intrinsic beat) | Failure to Sense (Undersensing) | Increase sensitivity (lower mV); urgent review |
| Pacemaker inhibited by noise/artefact | Oversensing | Remove EMI; decrease sensitivity |
| Rapid pacing at abnormal rate (>200 bpm) | Runaway Pacemaker | Apply magnet; emergency team |
| BP drop with VVI pacing, cannon waves | Pacemaker Syndrome | Notify EP; reprogram to DDD |
| Spike followed by LBBB-pattern QRS | Normal RV Pacing | No action — expected finding |
| Two spikes (short gap) then wide QRS | Normal DDD Pacing | No action — expected finding |
First 24 Hours
- Continuous ECG monitoring — verify pacing and sensing
- CXR within 1 hour — rule out pneumothorax, confirm lead position
- Wound check every 4 hours — haemostasis
- Arm restriction ipsilateral side — no overhead movements
- 12-lead ECG — document baseline paced morphology
- Device settings verified against programmer printout
Before Discharge
- Device ID card issued — patient must carry at all times
- Driving restriction explained and documented
- Follow-up booked: 1-week wound, 6-week device check
- Emergency symptoms listed: syncope, shoulder pain, rapid pulse, infection
- MRI compatibility status documented
- Wound care instructions in writing (keep dry 5–7 days)
1. A patient with complete heart block has a VVI pacemaker. The ECG shows pacing spikes followed by wide QRS complexes. The patient reports dizziness and has cannon A-waves on examination. What is the most likely diagnosis?
2. A nurse observes pacing spikes on the ECG monitor but no QRS complexes follow each spike. The patient has a temporary transvenous pacemaker set at 70 bpm. The HR on the monitor reads 40 bpm. What is the priority nursing action?
3. Which pacemaker mode is MOST appropriate for a patient with sick sinus syndrome and an intact AV node?
4. A patient with a permanent pacemaker is admitted for an elective surgical procedure requiring monopolar electrocautery. What is the MOST important pre-operative nursing preparation?
5. According to GCC/UAE guidelines, a patient who received an appropriate ICD shock for VF should be advised NOT to drive for a minimum of:
6. Cardiac resynchronisation therapy (CRT) is indicated in a patient with heart failure. Which ECG finding provides the STRONGEST indication for CRT?