ECG TRIGGERING
Normal sinus rhythm
Retrospectively gate.
Irregular rate, no identifiable QRS complex
Retrospectively gate.
Use "Arrythmia Detection" and set the value to 300-400.
This will reject data from a heartbeat in which the next R wave came earlier or later than a 300-400 msec window centered on the expected R wave.
Breathhold time will increase.
Irregular rate, but good QRS complex
Neither retrospective or prospective triggering will work if the scanner cannot identify QRS complexes accurately.
First step - adjust ECG leads, and relearn VCG
Second step - reboot system
If this doesn't work, the exact can only be performed with real-time acquisitions and may not be diagnostic depending on the clinical indication