Temporary Cardiac Pacing in ICU 

Definition

Temporary cardiac pacing refers to short-term electrical stimulation of the heart to maintain adequate heart rate and cardiac output in patients with reversible or potentially reversible bradyarrhythmias or conduction disturbances.

 

Physiological Rationale

Bradyarrhythmias → ↓ HR → ↓ CO → hypotension, shock, ischemia, syncope, cardiac arrest

CO = HR × SV
When SV cannot compensate → pacing becomes life-saving

 

Indications for Temporary Pacing (EXAM-FAVORITE)

A. Absolute Indications

(Any of the following with hemodynamic compromise)

  1. Symptomatic bradycardia
    • Hypotension
    • Altered sensorium
    • Ischemic chest pain
    • Acute heart failure
    • Shock
  1. High-grade AV block
    • Mobitz type II
    • Complete heart block (3° AV block)
    • Advanced 2:1 AV block with wide QRS
  1. Asystole / severe bradycardia
    • HR < 30–40/min with symptoms

 

B. Relative / Prophylactic Indications

  • Inferior MI with transient AV block
  • Anterior MI with new BBB
  • Drug-induced bradycardia (β-blockers, CCBs, digoxin)
  • Post-cardiac surgery conduction block
  • Electrolyte-induced AV block (hyperkalemia)
  • Before procedures causing bradycardia (e.g., TAVI, ablation)

 

Types of Temporary Pacing (VERY IMPORTANT TABLE)

Type

Route

ICU Use

Advantages

Limitations

Transcutaneous (TCP)

Skin pads

Emergency

Fast, non-invasive

Painful, unreliable capture

Transvenous (TVP)

Central vein → RV

ICU standard

Reliable, sustained

Invasive, complications

Epicardial

Surgical wires

Post-cardiac surgery

Stable threshold

Surgical only

Transesophageal

Esophagus

Rare ICU use

Atrial pacing

Poor ventricular capture

 

Transcutaneous Pacing (TCP)

Indications

  • Immediate stabilization in unstable bradycardia
  • Bridge to transvenous pacing

Technique

  • Anterior–posterior pad placement
  • Start:
    • Rate: 70–80 bpm
    • Current: Start at 50 mA → increase until capture

Confirmation of Capture

  • Electrical capture (paced QRS)
  • Mechanical capture (pulse, BP rise) → MUST confirm

Sedation

  • Often required due to severe pain
  • Midazolam / fentanyl (if BP allows)

⚠️ Exam Pearl: Electrical capture ≠ mechanical capture

 

Transvenous Temporary Pacing (TVP) – CORE ICU SECTION

Venous Access

Site

Advantage

Disadvantage

Right internal jugular (preferred)

Straight path to RV

Infection risk

Femoral vein

Easy, fast

Infection, DVT

Subclavian

Stable

Pneumothorax

 

Catheter Placement

  • Balloon-tipped pacing catheter
  • Advanced under:
    • ECG guidance (paced beats)
    • Fluoroscopy (ideal)
    • Echo guidance (ICU increasingly common)

Final Position

  • Right ventricular apex or septum

 

Pacing Modes in Temporary Pacemakers

Mode

Meaning

ICU Use

VVI

Ventricular pace, sense, inhibit

Most common

AAI

Atrial pacing

Rare

DDD

Dual chamber

Rare in ICU

👉 VVI is default in ICU

 

Pacemaker Settings (HIGH-YIELD)

Rate

  • 60–80 bpm (individualized)

Output (mA)

  • Find capture threshold
  • Set output = 2–3 × capture threshold

Sensitivity

  • Adjust to avoid:
    • Undersensing → inappropriate pacing
    • Oversensing → pacing inhibition

 

Confirmation of Effective Pacing

Electrical Capture

  • Paced QRS after pacing spike
  • Wide QRS (LBBB-like morphology)

Mechanical Capture (MOST IMPORTANT)

  • Palpable pulse
  • Improved BP
  • Arterial waveform
  • Echo showing ventricular contraction

 

Common Complications (EXAM FAVORITE)

Procedure-Related

  • Pneumothorax
  • Hematoma
  • Arterial puncture
  • Air embolism

Catheter-Related

  • Failure to capture
  • Lead dislodgement
  • RV perforation → tamponade
  • Ventricular arrhythmias
  • Tricuspid regurgitation

Infection

  • Sepsis
  • Endocarditis (prolonged use)

 

Causes of Failure to Capture (VERY IMPORTANT)

Cause

Mechanism

Lead displacement

Loss of myocardial contact

↑ pacing threshold

MI, ischemia, fibrosis

Electrolyte imbalance

Hyperkalemia, acidosis

Drug effects

Antiarrhythmics

Battery failure

Equipment issue

 

Temporary Pacing in Special ICU Situations

1. Acute MI

  • Inferior MI: usually transient AV block
  • Anterior MI: extensive conduction disease → poor prognosis

2. Hyperkalemia

  • Pacing may fail
  • Correct K⁺ urgently (Ca²⁺, insulin, dialysis)

3. Drug-Induced Bradycardia

  • TVP as bridge until drug clearance
  • Along with antidotes (glucagon, calcium)

 

Duration of Temporary Pacing

  • Shortest possible duration
  • If pacing required > 5–7 days → evaluate for permanent pacemaker

 

When to Convert to Permanent Pacemaker

  • Persistent high-grade AV block
  • No reversible cause
  • Post-MI AV block not resolving
  • Symptomatic sinus node dysfunction

 

Exam Pearls & Pitfalls

  • TCP is bridge therapy, not definitive
  • Always confirm mechanical capture
  • VVI mode is most commonly used
  • Hyperkalemia → pacing may be ineffective
  • Prolonged temporary pacing ↑ infection risk