Determining Good Capture in a Paced Rhythm

Primary Methods for Assessing Capture

The American Heart Association and American College of Cardiology recommend verifying that each pacing stimulus produces a corresponding mechanical systole, confirmed by observing a QRS complex following each pacing spike on ECG and confirming peripheral pulse generation through arterial pressure monitoring, pulse oximetry plethysmogram, or manual pulse palpation 1, 2, 3
Verify that each pacing artifact is followed by a QRS complex (for ventricular pacing) or P wave (for atrial pacing) with appropriate morphology, as recommended by the European Society of Cardiology 4
Optimize ECG lead selection to minimize pacemaker artifact and maximize QRS visualization, as suggested by the American Heart Association 1, 5

Monitor peripheral pulse through arterial line waveform, pulse oximeter plethysmogram, or manual palpation to confirm each pacing stimulus produces a mechanical systole, as recommended by the American Society of Anesthesiologists 2, 3
Verify hemodynamic response - adequate blood pressure and perfusion confirm effective mechanical capture, according to the American College of Cardiology 1

Evaluate sensing parameters - appropriate sensing prevents oversensing that could inhibit pacing output, as recommended by the European Heart Journal 6
Confirm biventricular capture by analyzing the paced QRS morphology - look for positive R-wave in V1, as absence may indicate LV lead displacement or loss of LV capture, according to the European Journal of Heart Failure 4

Perform threshold testing by gradually decreasing pacing output until loss of capture occurs, then program output with adequate safety margin, as recommended by the European Heart Journal 6

Lead dislodgement - most common cause, occurring in 1-2% of pacemaker cases and up to 5.7% of CRT cases, with 50% occurring within first 24 hours, according to the American Heart Association and European Heart Journal 1, 6
Oversensing - large P or T waves, muscle artifact, or electrical interference can inhibit pacing output, as reported by the American Heart Association 1, 7

Continuous ECG monitoring for 12-24 hours post-implantation to detect early lead dislodgement, as recommended by the American College of Cardiology 8
All patients with temporary transvenous pacing require continuous monitoring until device removal or replacement with permanent system, according to the American Heart Association 1, 7

When the patient’s native heart rate exceeds the programmed lower rate limit, a VVI or DDD pacemaker should inhibit pacing, resulting in no spikes on the ECG【9】.
In a normal intrinsic rhythm the pacemaker does not emit spikes because it correctly senses native cardiac activity and remains inhibited【9】.
Each intrinsic ventricular beat occurs before the programmed escape interval expires, confirming proper sensing and inhibition by the device【9】.

Peripheral pulse assessment (arterial line waveform, pulse‑ox plethysmography, or manual palpation) must be used to verify that every ECG‑recorded beat—whether accompanied by a spike or not—produces a mechanical systole【9】.

Intrinsic QRS complexes are usually narrower than paced QRS complexes, unless the patient has a pre‑existing bundle‑branch block【9】.
The complete absence of pacemaker spikes when the intrinsic rhythm is adequate is a normal finding and does not indicate device malfunction【9】.
If the intrinsic rate falls below the programmed lower rate limit, pacing spikes should appear on the ECG, reflecting appropriate device activation【9】.

The only conclusive method to differentiate normal pacemaker function from malfunction is to interrogate the device with the manufacturer’s programmer, as recommended by the American Society of Anesthesiologists (ASA) guidelines【9】.