capture threshold
The minimum electrical energy required from a pacemaker to consistently stimulate myocardial contraction.
Full Definition
Capture threshold represents the lowest pacemaker output (measured in volts or milliamperes) that reliably depolarizes cardiac tissue and produces a mechanical contraction. This parameter is routinely assessed during pacemaker implantation and follow-up visits to ensure adequate safety margins while optimizing battery longevity. Threshold testing involves systematically decreasing pacemaker output until loss of capture occurs, then setting the permanent output at a safe margin above this threshold. Factors affecting capture threshold include lead position, tissue maturation, medications, and metabolic conditions.
Usage
Usage note: Express measurements with units (volts/milliamperes) and pulse width; distinguish from sensing parameters.
In Context
- "Atrial capture threshold measured 0.8V at 0.5ms pulse width with adequate safety margin." — Pacemaker implant procedure note
- "Rising capture thresholds may indicate lead displacement or exit block requiring intervention." — Device clinic follow-up report