# Electroanatomic mapping
Electroanatomic mapping (EAM) is a cardiac electrophysiology technique that builds three-dimensional, navigable maps of electrical activity inside the heart chambers to guide diagnosis and catheter ablation of arrhythmias. A map combines a reconstructed chamber geometry with color-coded electrical data: activation maps time each electrogram (a recording of the heart's electrical activity) against a reference within a window of interest, voltage maps quantify scar from bipolar or unipolar amplitude, and propagation maps animate the wavefront crossing the chamber during the cycle.[1](https://pubmed.ncbi.nlm.nih.gov/18270601/) • [2](https://clinicalpub.com/electroanatomic-mapping-and-magnetic-guidance-systems/) These displays show catheter positions without fluoroscopy.[1](https://pubmed.ncbi.nlm.nih.gov/18270601/) Systems are classified by localization technology (magnetic-based versus impedance-based) and by data collection (contact versus noncontact).[3](https://www.ovid.com/journals/jarry/pdf/10.1002/joa3.12308~2019-aphrs-expert-consensus-statement-on-threedimensional)
| Key fact | Detail |
|---|---|
| What the map shows | Chamber geometry with activation times, voltage (scar), propagation, and tagged ablation lesions, registered to CT/MRI or ultrasound images[1](https://pubmed.ncbi.nlm.nih.gov/18270601/) |
| Localization principle | Magnetic triangulation from a low-field pad (0.02–0.5 G), or impedance sensing of transthoracic electric fields; hybrid systems combine both[4](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426) • [5](https://www.sciencedirect.com/science/article/pii/S1875213618300901) |
| Location accuracy | About 0.5 mm for magnetic and 0.6 mm for impedance-based catheters; sensor accuracy 0.8 mm and 5° in the original validation[4](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426) • [5](https://www.sciencedirect.com/science/article/pii/S1875213618300901) |
| Point density | High-density maps are conventionally >400 points, typically 2000–6000 per chamber; automated basket mapping collects about 25 times more points than manual mapping[6](https://www.nature.com/articles/s41598-021-96004-4) • [3](https://www.ovid.com/journals/jarry/pdf/10.1002/joa3.12308~2019-aphrs-expert-consensus-statement-on-threedimensional) |
| Radiation effect | Randomized data show fluoroscopy time falling from 28.8 to 9.3 minutes and dose from 20.8 to 6.2 Gray[7](https://onlinelibrary.wiley.com/doi/10.1111/j.1540-8167.2004.03356.x) |
| Outcome effect | Procedural efficiency improves consistently, but randomized multicenter studies have not shown improved ablation success, with AF success about 45–55% at 12–18 months[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) |
| Adoption | More than 90% of ablation procedures worldwide now use navigable catheters and 3D mapping, per the system inventor's 2025 account[9](https://doi.org/10.1016/j.hrthm.2024.10.040) |
## How it works
**Magnetic localization** underlies the CARTO platform. A location pad under the patient generates a very low-intensity magnetic field of 0.02 to 0.5 G, and a sensor mounted in the distal catheter tip reports position on the x, y, and z axes plus rotation in pitch, yaw, and roll.[4](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426) The field strength each coil produces, arranged as a triangle beneath the thorax, is inversely proportional to the sensor-coil distance, so the system triangulates the tip position in [six degrees of freedom](https://www.edgepedia.org/six-degrees-of-freedom); an external reference patch on the patient's back detects patient movement.[5](https://www.sciencedirect.com/science/article/pii/S1875213618300901) Sensor accuracy in this field is 0.8 mm and 5°.[4](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426)
**Impedance localization**, used by the EnSite platform, sends an 8 kHz signal alternately through three pairs of surface electrodes (anterior-posterior, lateral, and neck-leg), forming orthogonal transthoracic electric fields with the heart at the center; each catheter electrode senses the voltage gradient along each axis, so the system computes the three-dimensional position of all electrodes simultaneously and can track any standard catheter.[10](https://www.cardiovascular.abbott/int/en/hcp/products/electrophysiology/mapping-systems/ensite/about/how-it-works.html)
**Hybrid and noncontact collection.** CARTO 3 adds current-based Advanced Catheter Location, in which each electrode emits current at a unique frequency, to adjust the magnetically derived data.[11](https://www.accessdata.fda.gov/cdrh_docs/pdf9/K090017.pdf) • [8](https://link.springer.com/article/10.1007/s11936-024-01034-6) Rhythmia HDx performs continuous mapping and continuous localization using both magnetic and impedance tracking.[12](https://www.bostonscientific.com/content/dam/elabeling/ep/rhythmia-mapping-system/rhythmia_6-0_mappingsystem/51660904-01A_RHY_HDX_IFU_OUS_ML_s.pdf) In noncontact mapping, a 64-electrode array on an intracavitary balloon records far-field potentials and reconstructs 3,360 virtual electrograms on the endocardial surface through the inverse solution of Laplace's law, with accuracy best within 40 mm of the array center.[13](https://www.aerjournal.com/articles/contemporary-mapping-techniques-complex-cardiac-arrhythmias-identifying-and-modifying?language_content_entity=en)
## How it is done
Contact mapping accepts a point only when stability criteria are met, classically less than 4 mm of spatial movement and 4 ms of local activation-time variation between beats.[4](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426) Automated high-density systems instead apply continuous acquisition with user-set beat acceptance criteria; the Rhythmia workflow, for example, gates on cycle length variation under 10 ms, propagation reference under 5 ms, respiration artifact under 10–15 μV, catheter movement under 1 mm, electrogram stability under 25%, and tracking quality under 3 mm.[6](https://www.nature.com/articles/s41598-021-96004-4)
**Substrate annotation** converts electrogram amplitudes into tissue categories. A bipolar threshold of ≤0.5 mV has been arbitrarily selected for low-voltage scar delineation,[1](https://pubmed.ncbi.nlm.nih.gov/18270601/) while bipolar amplitude above 1.5 mV appears in over 95% of normal ventricular endocardial sites and amplitude below 1.5 mV is associated with fibrosis occupying more than 75% of adjacent left ventricular wall thickness; the threshold's sensitivity is limited because normal endocardium overlying fibrosis can still exceed 1.5 mV.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) Pre-acquired CT or MRI images can be merged with the electroanatomic map (CARTOMERGE software), and intracardiac echo can drive geometry creation (CARTOSOUND).[14](https://www.blackwellpublishing.com/content/bpl_images/content_store/sample_chapter/9781405157025/9781405157025_4_C001.pdf) • [11](https://www.accessdata.fda.gov/cdrh_docs/pdf9/K090017.pdf)
## Origin
Three-dimensional electroanatomic mapping systems were first proposed in the 1990s; the initial systems were CARTO, the ultrasound-based RPM with dedicated catheters, and LocaLisa, which used an electrical field with standard catheters.[5](https://www.sciencedirect.com/science/article/pii/S1875213618300901) The noncontact approach has a documented experimental lineage: Dirar S. Khoury and colleagues published three-dimensional electrophysiological imaging of the intact canine left ventricle with a noncontact multielectrode cavitary probe in Circulation in 1998,[15](https://doi.org/10.1161/01.cir.97.4.399) and the EnSite 3000/Array system used a 9-Fr catheter with a 7.6 mL (18 × 40 mm) ellipsoid balloon surrounded by a 64-electrode multielectrode array, capable of mapping nonsustained or hemodynamically unstable arrhythmias.[14](https://www.blackwellpublishing.com/content/bpl_images/content_store/sample_chapter/9781405157025/9781405157025_4_C001.pdf)
[Paulus Kirchhof](https://www.edgepedia.org/paulus-kirchhof) and colleagues described the LocaLisa nonfluoroscopic catheter visualization system, which reduced radiation exposure during supraventricular tachycardia ablation, in The American Journal of Cardiology in 2002.[16](https://doi.org/10.1016/s0002-9149%2802%2902481-5) Mark J. Earley and colleagues validated the noncontact mapping system in the left atrium in JACC in 2006,[17](https://doi.org/10.1016/j.jacc.2006.04.069) P. M. Kistler and colleagues randomized CT image integration into EAM-guided atrial fibrillation ablation in the [European Heart Journal](https://www.edgepedia.org/european-heart-journal) in 2008,[18](https://doi.org/10.1093/eurheartj/ehn453) and Nick W.F. Linton and colleagues introduced cardiac ripple mapping, a three-dimensional visualization method for use with EAM, in [Heart Rhythm](https://www.edgepedia.org/heart-rhythm) in 2009.[19](https://doi.org/10.1016/j.hrthm.2009.08.038) Contact-force information was later integrated into EAM workflows through Vivek Y. Reddy and colleagues' randomized trial of a contact force-sensing irrigated catheter (Circulation, 2015),[20](https://doi.org/10.1161/circulationaha.114.014092) Josef Kautzner and colleagues' EFFICAS II optimization of contact force for pulmonary vein isolation (EP Europace, 2015),[21](https://doi.org/10.1093/europace/euv057) and Ahmed Hussein and colleagues' prospective use of Ablation Index targets (Journal of Cardiovascular Electrophysiology, 2017).[22](https://doi.org/10.1111/jce.13281)
## Variants
Three platforms dominate clinical practice: Carto 3 (Biosense-Webster), EnSite Precision/X (Abbott), and Rhythmia HDx ([Boston Scientific](https://www.edgepedia.org/boston-scientific)), all building near real-time maps registered to tomographic images.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) Carto 3 pairs magnetic navigation with current-based localization for a reported spatial resolution under 1 mm and provides an ablation index combining stability, contact force, time, and power.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) EnSite Precision corrects nonlinear impedance via field scaling, the newer X systems add magnetic localization of sensor-enabled devices, and its LSI index combines contact force, radiofrequency duration, and current.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) • [10](https://www.cardiovascular.abbott/int/en/hcp/products/electrophysiology/mapping-systems/ensite/about/how-it-works.html)
**Rhythmia HDx** maps continuously from the 64-electrode IntellaMap Orion mini-basket (eight splines of eight flat, iridium-oxide-coated 0.4 mm² electrodes at 2.5 mm spacing, variable 3–22 mm diameter) with a 0.01 mV noise floor, and analyzes the maximum negative \( dV/dt \) of unipolar electrograms to eliminate far-field signals.[3](https://www.ovid.com/journals/jarry/pdf/10.1002/joa3.12308~2019-aphrs-expert-consensus-statement-on-threedimensional) • [8](https://link.springer.com/article/10.1007/s11936-024-01034-6) The KODEX-EPD system (EPD Solutions, Philips) uses wide-band dielectric imaging; Alexander Romanov and colleagues reported high-resolution, real-time, nonfluoroscopic 3D cardiac imaging and catheter navigation in humans with it in Heart Rhythm in 2019.[23](https://doi.org/10.1016/j.hrthm.2019.06.020)
## Applications
**Radiation and efficiency.** In a randomized study of 102 patients, CARTO guidance reduced fluoroscopy time from 28.8 (SD 19.5) to 9.3 (SD 7.6) minutes and radiation dose from 20.8 (SD 32.7) to 6.2 (SD 6.1) [Gray](https://www.edgepedia.org/gray-unit), used fewer catheters (2.5 vs 4.4) but carried higher catheter costs (13.8 vs 9.3 units, one unit equal to the cost of a nonsteerable quadripolar catheter), with similar acute success and procedure duration.[7](https://onlinelibrary.wiley.com/doi/10.1111/j.1540-8167.2004.03356.x) [Meta-analysis](https://www.edgepedia.org/meta-analysis) of randomized and non-randomized studies concluded 3D mapping is safe and consistently shortens fluoroscopy duration and radiation exposure, with a non-significant trend toward lower failure rates.[5](https://www.sciencedirect.com/science/article/pii/S1875213618300901)
**Against alternatives.** In a randomized trial of 80 AVNRT patients, intracardiac echocardiography (ICE) guidance shortened total procedure time (61.0 vs 71.5 min) and ablation time compared with CARTO 3 guidance, but EAM guidance achieved zero fluoroscopy (0 vs 83.5 s) and lower radiation dose (0 vs 3.3 mGy); 22.5% of the EAM group crossed over to ICE, and both arms reached 100% acute success.[24](https://mdpi-res.com/d_attachment/jcm/jcm-12-05577/article_deploy/jcm-12-05577-v2.pdf?version=1693194499) ICE catheters require 8F to 11F sheaths, which may raise access-site complications and limit use in smaller patients.[25](https://link.springer.com/content/pdf/10.1007/s11886-021-01461-y.pdf?error=cookies_not_supported&code=d22279cd-9fae-43f0-b524-ed61b4e0b42a) Noncontact mapping remains valuable for non-tolerated or non-sustained arrhythmias, though it is used less often today.[5](https://www.sciencedirect.com/science/article/pii/S1875213618300901)
**Outcomes and the pulsed-field era.** Despite mapping advances, AF ablation success remains about 45–55% over 12–18 months, and none of the advanced AF mapping systems has improved ablation success in randomized multicenter studies.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6) EAM has also taken on lesion quality assessment for pulsed field ablation (PFA): in 100 consecutive first-time PFA patients, post-ablation CARTO 3 voltage maps (ablated tissue below 0.05 mV, viable tissue above 0.5 mV) identified incomplete lesions in 16% of PVI-only and 48% of PVI-plus-posterior-wall patients, with detection rates unaffected by operator learning curve.
## Limitations and alternatives
Map accuracy depends on location-system noise, fiducial reproducibility, cardiac and respiratory mechanics, electrogram annotation, catheter contact, sampling density, rhythm, wavefront direction, and electrode size and spacing.[2](https://clinicalpub.com/electroanatomic-mapping-and-magnetic-guidance-systems/) Incorrect application, such as a wrong tachycardia cycle length window or wrong electrogram annotation, can produce confusing erroneous activation maps and should not replace careful interpretation of the data.[1](https://pubmed.ncbi.nlm.nih.gov/18270601/) Impedance-based systems are more susceptible to field distortion and drift, whereas magnetic systems may offer greater positional stability but require specialized hardware.[26](https://pmc.ncbi.nlm.nih.gov/articles/PMC12471145/) Inadequate catheter contact and catheter-induced ectopy remain impediments to voltage mapping with multipolar catheters.[8](https://link.springer.com/article/10.1007/s11936-024-01034-6)
[Activation mapping](https://www.edgepedia.org/activation-mapping)'s main limitation is the time needed for complete mapping, so the tachycardia must be sustained or tolerated enough to map.[5](https://www.sciencedirect.com/science/article/pii/S1875213618300901) EAM maps delineate chamber geometry and surface contours but provide no information about tissue depth or wall composition.[26](https://pmc.ncbi.nlm.nih.gov/articles/PMC12471145/)
## References
1. [Principles of electroanatomic mapping (Bhakta & Miller, Indian Pacing Electrophysiol J 2008)](https://pubmed.ncbi.nlm.nih.gov/18270601/)
2. [Electroanatomic mapping and magnetic guidance systems (Clinical Tree)](https://clinicalpub.com/electroanatomic-mapping-and-magnetic-guidance-systems/)
3. [2019 APHRS expert consensus statement on three-dimensional mapping systems (J Arrhythm 2020)](https://www.ovid.com/journals/jarry/pdf/10.1002/joa3.12308~2019-aphrs-expert-consensus-statement-on-threedimensional)
4. [New Method for Nonfluoroscopic Endocardial Mapping in Humans | Circulation](https://www.ahajournals.org/doi/10.1161/01.CIR.97.24.2426)
5. [Three-dimensional mapping in the electrophysiological laboratory (review)](https://www.sciencedirect.com/science/article/pii/S1875213618300901)
6. [High density mapping guided partial antral ablation for a pulmonary vein isolation](https://www.nature.com/articles/s41598-021-96004-4)
7. [Electroanatomic Versus Fluoroscopic Mapping for Catheter Ablation Procedures: A Prospective Randomized Study](https://onlinelibrary.wiley.com/doi/10.1111/j.1540-8167.2004.03356.x)
8. [Advanced Electroanatomic Mapping: Current and Emerging Approaches (Narayan & John, Curr Treat Options Cardiovasc Med 2024)](https://link.springer.com/article/10.1007/s11936-024-01034-6)
9. [My journey with the CARTO system (Ben-Haim, Heart Rhythm 2025)](https://doi.org/10.1016/j.hrthm.2024.10.040)
10. [How the EnSite Precision Cardiac Mapping System Works (Abbott)](https://www.cardiovascular.abbott/int/en/hcp/products/electrophysiology/mapping-systems/ensite/about/how-it-works.html)
11. [FDA 510(k) K090017: CARTO 3 V1.0 EP Navigation System](https://www.accessdata.fda.gov/cdrh_docs/pdf9/K090017.pdf)
12. [RHYTHMIA HDx Mapping System Instructions for Use (Boston Scientific)](https://www.bostonscientific.com/content/dam/elabeling/ep/rhythmia-mapping-system/rhythmia_6-0_mappingsystem/51660904-01A_RHY_HDX_IFU_OUS_ML_s.pdf)
13. [Contemporary Mapping Techniques of Complex Cardiac Arrhythmias – Identifying and Modifying the Arrhythmogenic Substrate](https://www.aerjournal.com/articles/contemporary-mapping-techniques-complex-cardiac-arrhythmias-identifying-and-modifying?language_content_entity=en)
14. [Electroanatomic mapping (book chapter)](https://www.blackwellpublishing.com/content/bpl_images/content_store/sample_chapter/9781405157025/9781405157025_4_C001.pdf)
15. [Dirar S. Khoury and colleagues (1998). Three-Dimensional Electrophysiological Imaging of the Intact Canine Left Ventricle Using a Noncontact Multielectrode Cavitary Probe: Study of Sinus, Paced, and Spontaneous Premature Beats. Circulation.](https://doi.org/10.1161/01.cir.97.4.399)
16. [A novel nonfluoroscopic catheter visualization system (LocaLisa) to reduce radiation exposure during catheter ablation of supraventricular tachycardias (The American Journal of Cardiology, 2002)](https://doi.org/10.1016/s0002-9149%2802%2902481-5)
17. [Mark J. Earley and colleagues (2006). Validation of the Noncontact Mapping System in the Left Atrium During Permanent Atrial Fibrillation and Sinus Rhythm. Journal of the American College of Cardiology.](https://doi.org/10.1016/j.jacc.2006.04.069)
18. [P. M. Kistler and colleagues (2008). The impact of image integration on catheter ablation of atrial fibrillation using electroanatomic mapping: a prospective randomized study. European Heart Journal.](https://doi.org/10.1093/eurheartj/ehn453)
19. [Nick W.F. Linton and colleagues (2009). Cardiac ripple mapping: A novel three-dimensional visualization method for use with electroanatomic mapping of cardiac arrhythmias. Heart Rhythm.](https://doi.org/10.1016/j.hrthm.2009.08.038)
20. [Vivek Y. Reddy and colleagues (2015). Randomized, Controlled Trial of the Safety and Effectiveness of a Contact Force–Sensing Irrigated Catheter for Ablation of Paroxysmal Atrial Fibrillation. Circulation.](https://doi.org/10.1161/circulationaha.114.014092)
21. [Josef Kautzner and colleagues (2015). EFFICAS II: optimization of catheter contact force improves outcome of pulmonary vein isolation for paroxysmal atrial fibrillation. EP Europace.](https://doi.org/10.1093/europace/euv057)
22. [Ahmed Hussein and colleagues (2017). Prospective use of Ablation Index targets improves clinical outcomes following ablation for atrial fibrillation. Journal of Cardiovascular Electrophysiology.](https://doi.org/10.1111/jce.13281)
23. [Alexander Romanov and colleagues (2019). High-resolution, real-time, and nonfluoroscopic 3-dimensional cardiac imaging and catheter navigation in humans using a novel dielectric-based system. Heart Rhythm.](https://doi.org/10.1016/j.hrthm.2019.06.020)
24. [Electroanatomical Mapping System-Guided vs. Intracardiac Echocardiography-Guided Slow Pathway Ablation: A Randomized, Single-Center Trial (J Clin Med, 2023)](https://mdpi-res.com/d_attachment/jcm/jcm-12-05577/article_deploy/jcm-12-05577-v2.pdf?version=1693194499)
25. [Into a Fluoroless Future: an Appraisal of Fluoroscopy-Free Techniques in Clinical Cardiac Electrophysiology (Curr Treat Options Cardiovasc Med, 2021)](https://link.springer.com/content/pdf/10.1007/s11886-021-01461-y.pdf?error=cookies_not_supported&code=d22279cd-9fae-43f0-b524-ed61b4e0b42a)
26. [Expanding Applications of Three-Dimensional Cardiac Mapping Systems: A Review (PMC, 2025)](https://pmc.ncbi.nlm.nih.gov/articles/PMC12471145/)
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*Topic: Encyclopedia › Life and health › Human health and medicine › Clinical assessment and procedures › Diagnosis and clinical assessment › Diagnostic classification and scoring › Neurological rating scales*
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