Temporary Transvenous & Epicardial Pacing

An external pulse generator sends an electrical impulse to the heart. The route is a catheter placed in the right ventricle (transvenous) or wires sewn to the heart surface (epicardial). Use it when the heart cannot generate a rate or conduction that keeps the patient perfused. It bridges the time until a permanent solution or recovery. It is a bridge, not a fix.

Key Components

Flow Path

1. Generator: sets the rate, output and sensitivity.
2. Lead: the impulse runs down the wire or catheter.
3. Myocardium: once the impulse clears the threshold, the chamber depolarizes. That is capture.
4. Sensing: it listens for the native beat, then inhibits or triggers as programmed.

Transcutaneous pacing runs on skin pads with its own settings. The transcutaneous pacing page covers that route.

What It Does

What It Depends On

• Lead position and tissue contact. The threshold and sensing change when the lead moves.
• Electrolytes and acid-base status (potassium, pH, calcium)
• Native conduction. A pacer-dependent patient has no reliable escape rhythm to fall back on.
• Drugs that change the threshold or conduction (antiarrhythmics, some sedatives)
• Pacing mode and whether the atria are paced or only sensed

Pacing Mode Letters (NBG Code)

Common Modes

• VVI: ventricular pacing. A native ventricular beat inhibits it. This is the usual temporary mode.
• AAI: atrial pacing with intact AV conduction.
• DDD: dual-chamber. It tracks the atria while AV conduction is intact. It needs both leads.
• Asynchronous (VOO or DOO): it paces at a fixed rate and ignores the native rhythm. It is used to stop oversensing or inhibition during electrocautery. The trap: a spike that lands on a native T wave can cause R-on-T and VF.

Indications

• Symptomatic bradycardia with poor perfusion that does not respond to drug therapy, per the local bradycardia algorithm
• Symptomatic Mobitz II or complete (third-degree) AV block, especially with a wide QRS or an unreliable escape rhythm
• Sinus node dysfunction with symptoms, as a bridge to a permanent device
• Bradyarrhythmia after cardiac surgery, with epicardial wires in place
• Bradycardia from drug toxicity, when drug therapy has failed and the team is arranging a pacing route

Contraindications

Limitations

• Transvenous pacing needs an operator who can place the lead and position it by fluoroscopy or ECG guidance
• Epicardial wires depend on where the surgeon placed them. Their function changes as the myocardium heals
• Temporary pacing does not treat the cause of the bradycardia

Key Evidence

Protocol-dependent. The margin for pacing output and the threshold to start pacing vary between institutions. This page sets no single number for either.

Targets

Initial Settings

1. Confirm the indication and the order; set the mode the order specifies.
2. Set the rate; start at the ordered rate.
3. Increase output in steps until capture is seen on the ECG and the pulse is checked.
4. Decrease output in steps to find the threshold (the lowest output with capture); set the working output above the threshold by the protocol margin.
5. Set sensitivity so the generator senses the native rhythm; test it by watching for inhibition with a native beat.

Sizing & Positioning

• Transvenous: fluoroscopy or the ECG pattern, plus a chest X-ray, confirm the tip position in the RV apex, per local protocol.
• Epicardial: the surgeon records which wires are atrial and which are ventricular. Keep that record with the generator.

Normal

• Capture looks like this: a spike, then a wide QRS, with the T wave pointing the opposite way, at the set rate.
• Demand pacing goes quiet when the native beat is there and sensed. No spike.
• In DDD, the atrial spike comes first. The ventricular spike follows after the programmed AV delay.

Abnormal Patterns

Positioning & Mobility

• Leads stay secured. On every move, protect them and keep the generator on the bed or in the transport case
• The entry site decides how you position the limb or neck. Avoid pulling on the cable

Tag heparin High-alert. Refer to the heparin page and the aPTT page.

Bleeding & Platelets

• Venous puncture hematoma: pressure and a dressing, check the neck or groin each shift
• Pericardial bleeding: falling blood pressure and a rising heart rate after lead placement; call immediately
• Thrombocytopenia: check the platelet count (see the platelets page)

Readiness Criteria

• The native rhythm is stable with an adequate escape rate, per the order
• Capture and sensing are stable on the current settings
• The cause of the bradycardia has resolved or is controlled
• The electrolytes are corrected

Weaning Steps

1. Lower the rate in steps, or switch to demand mode, per the order.
2. Watch the native rhythm and perfusion at each step.
3. Pause pacing only under an order, with a team present and a backup ready.

Failure Criteria: Step Back Up

• Falling blood pressure, altered mental status or chest pain with the native rate
• Pauses or junctional or idioventricular escape that is too slow

Removal & Post-Removal Care

• Removal per the order and the local protocol
• The surgical team removes epicardial wires per protocol. Do not pull against resistance
• Watch the site for bleeding. Check the chest X-ray per protocol after a transvenous removal

Before You Move

1. Check battery charge and carry a charged spare.
2. Confirm the mode, rate and output with the sending team; write them down.
3. Secure the leads and cables; keep the generator where it cannot be knocked.
4. Have transcutaneous pads ready for a backup route.
5. Have an experienced operator and an airway and drug plan.

If You Are Not the Device Specialist

• Watch the ECG for capture and the pulse with each paced beat.
• Do not disconnect the leads, change the mode or change the output.
• If capture is lost or the patient is unstable, start the transcutaneous route per protocol and call the team.
• Do not reposition a transvenous lead.

During Transport

• Keep the patient on the monitor with the pacing settings recorded
• Check the entry site and dressing at each handoff

Air Medical & Altitude

Battery life and device function at altitude depend on the manufacturer and on protocol. Check the transport team's device guidance before flight.

Handoff

• Mode, rate and output; last capture check
• Lead type and entry site; any repositioning
• Anticoagulation status and recent platelet count
• Recent alarms or complications

Pediatric & Neonatal

After pediatric cardiac surgery, epicardial wires are common. Pediatric thresholds, outputs and rates differ from adult values. They follow the pediatric cardiology protocol. The adult numbers on this page do not apply to children.

For the broader approach, see the pediatric shock page.

Pregnancy & Peripartum

Transvenous placement means fluoroscopy. Shield the abdomen and limit exposure per protocol. The team should talk through fetal dose with the radiology team. Pacing itself is managed the same way, with the obstetric team involved.

Systematic Walk-Through

1. Indication: why is the patient bradycardic, and is pacing needed now?
2. Route: transcutaneous, transvenous or epicardial?
3. Mode and settings: as ordered.
4. Capture: is there a QRS after each spike, and a pulse?
5. Sensing: does the generator inhibit when the native rhythm returns?
6. Complications and goal: what is the patient's plan today?

Pearls

• The spike proves nothing until a QRS follows it.
• A rising threshold is an early warning of a lead problem.
• Never turn off the generator in a pacer-dependent patient.
• The transcutaneous margin is a different number from the transvenous margin.