What we set up and why
A 3D mapping system — Carto from Biosense Webster or EnSite from Abbott — gives us catheter localization in space without continuous fluoroscopy, plus the ability to build anatomy, tag points, and create activation and voltage maps. Setup is the difference between mapping a smooth, accurate chamber and chasing drift artifacts all afternoon.
Patches and references
Carto (magnetic + impedance)
- Location pad under the patient, centered roughly at the heart
- Patient reference patch on the back, between the scapulae
- ECG patches for body surface ECG integration
- Confirm the magnetic field locator is positioned correctly under the table before the patient lies down
EnSite (impedance + magnetic depending on system)
- Six surface patches: anterior chest, back, lateral chest, lateral back, and limb patches
- Patches placed with patient supine, arms in final position — moving arms changes the field
- Skin must be dry; alcohol prep before patch placement helps adherence
- Confirm patch impedance values in normal range before drape
For either system: patches go on before the sterile drape. Adding a missing patch later means breaking the field.
System boot and pre-case check
- Power up the workstation as soon as the room turns over — software boot and patient registration take time
- Enter patient demographics from the order, double-checked against the wristband
- Select the case type — AF, atrial flutter, VT, SVT — this loads the right defaults
- Connect cables: catheter inputs, reference, system interface to the recording system
- Confirm signal acquisition: ECG visible, impedance values stable, no drift on a stationary catheter
Catheter setup
- Plug in the mapping catheter and confirm it shows on screen before insertion
- Confirm electrode spacing matches what the system expects (high-density vs. duo-decapolar vs. focal tip)
- Test electrode bipoles on the bench if signals look wrong — better to swap on the table than mid-map
- For ablation catheters, confirm impedance, temperature, and tip force readings are live
Building anatomy
Strategy varies by chamber and operator, but the principles are constant:
- Start with the catheter that builds anatomy best (high-density multi-electrode for chambers, ICE for left-sided)
- Sweep slowly along the wall — fast sweeps make jagged geometry
- Save anatomy at logical checkpoints — every chamber, before transseptal, after PVI
- Tag landmarks as we go: His, CS os, PV ostia, esophagus position
Map types we use
- Activation maps — color-coded timing of local activation; used for re-entry circuits and focal sources
- Voltage maps — peak-to-peak signal amplitude; scar appears as low voltage
- Propagation / Ripple — visualizing the wavefront moving through tissue
- CFAE / complex fractionated — historical for AF substrate, less used now
- Force / contact maps — for RF cases, shows where good contact was achieved
Common omissions to catch on the pre-case timeout
- Patches placed but not plugged in — system reads “no reference”
- Patient demographics wrong on the case file
- Old map from prior patient still loaded — happens more than we admit
- Mapping cable not connected to the recording system, so points won’t annotate
- Wrong catheter profile selected — measurements will be off
- ECG reference channel not chosen — annotations will float
Safety habits
- Save often. The system is software. Software crashes. Save anatomy after every meaningful checkpoint.
- Don’t move patches mid-case — if a patch peels off and gets replaced, the geometry shifts and the existing map is no longer accurate. Re-register if you have to.
- Watch impedance values during long cases — sweating, patient movement, and patch lift all change them.
- Backup fluoroscopy — if the mapping system fails, we can finish the case on fluoro. Know that fallback exists and have the C-arm settings ready.
- Communicate between operator and mapping tech: every point taken, every map saved, every change in catheter is called out.