endocardial pacing threshold
The minimum electrical energy required to consistently capture the heart muscle through an endocardial lead placed inside the heart chamber.
Full Definition
The endocardial pacing threshold represents the lowest electrical stimulus amplitude that reliably depolarizes cardiac tissue when delivered through a lead positioned on the inner surface of the heart chamber. This threshold is measured in volts or millijoules and is a critical parameter for programming pacemakers and ICDs to ensure adequate safety margins while preserving battery life. Threshold measurements are typically performed during device implantation and follow-up visits, with normal values ranging from 0.5-1.5 volts at 0.4-0.5 millisecond pulse width. Elevated thresholds may indicate lead maturation issues, fibrosis at the lead-tissue interface, or lead malfunction.
Usage
Usage note: Often abbreviated as 'pacing threshold' in clinical contexts, but editors should maintain the full term for clarity in technical documentation.
In Context
- "The endocardial pacing threshold remained stable at 0.8 volts throughout the six-month follow-up period." — Device interrogation report
- "An elevation in endocardial pacing threshold to 3.2 volts prompted lead revision surgery." — Clinical case report