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Pacemaker

The Anesthesia Guide » Topics » Pacemaker

Author:
Kai Knudsen



Updated:
6 May, 2025

A pacemaker generates electrical impulses to the heart in a regulated and controlled manner through an electrophysiological system that can be implanted in the body or external via transcutaneous electrodes.

Content:
  1. Pacemaker

Pacemaker

A pacemaker consists of two parts. One part is the pacemaker device, which is an encapsulated computer with a battery. The other part consists of the electrodes, which detect the heart rhythm and, if necessary, deliver electrical impulses to make the heart contract.

Implanted pacemaker:

  • A small device placed under the skin, usually near the collarbone.
  • Connected to the heart with one or more leads (wires) that deliver electrical impulses directly to the heart muscle.
  • Used for long-term treatment of slow or irregular heart rhythms.
  • Continuously monitors and adjusts the heart rate as needed.

External (transcutaneous) pacemaker:

  • A temporary device placed outside the body.
  • Delivers electrical impulses through electrodes attached to the skin (usually on the chest).
  • Used in emergency situations or short-term care, such as during surgery or acute heart rhythm disturbances.
  • Less comfortable than implanted pacemakers due to external stimulation.
An implantable ICD pacemaker with wires and a modem for remote monitoring. The device sends data to the hospital regularly.
In patients with severe heart failure, pacemaker implants can save lives. This is known as a heart failure pacemaker.
  • VOO = Fixed-rate ventricular pacing
  • VVI = Ventricular-inhibited pacing
  • AAI = Atrial-inhibited pacing
  • DDD = Dual atrial & ventricular pacing

Pace

  • Atrium
  • Ventricle
  • Dual (A+V)
  • O = None

Sense

  • Atrium
  • Ventricle
  • Dual (A+V)
  • O = None

Sense Response

  • Triggered
  • Inhibited
  • Dual (T+I)
  • O = None
Diagram of a pacemaker with dual chambers/electrodes.

External Temporary PM after Heart Surgery

Blue contact – atrium, white contact – ventricle

SC electrode to positive (+) pole

EMERGENCY – asynchronous high-energy stimulation with VVO (unlock the PM first!)

Pacemaker equipment for treating heart rate issues.

Stimulation

  • Atrial – normally 2-10 V (max range 0.1-18.0 V)
  • Ventricle – normally 5-10 V (max range 0.1-18.0 V)
  • Guideline – 5 V above capture threshold

Sensing

  • Atrial – normally 0.5-1 mV (max range 0.2-20 mV)
  • Ventricle – normally 2-3 mV (max range 1.0-20 mV)
  • AV interval usually 150-180 ms – compare with patient’s PQ time

 

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