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W. B. Buchenberg 1 , G. Hoppe 1 , R. Lorenz 1 , W. Mader 2 , P. Laudy 3 ,

Experimental Study of the Magnetohydrodynamic (MHD) Effect with respect to Intracardiac ECG Signals. W. B. Buchenberg 1 , G. Hoppe 1 , R. Lorenz 1 , W. Mader 2 , P. Laudy 3 , C . Bienek 4 and B. Jung 1

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W. B. Buchenberg 1 , G. Hoppe 1 , R. Lorenz 1 , W. Mader 2 , P. Laudy 3 ,

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  1. Experimental Study of the Magnetohydrodynamic (MHD) Effect with respect to Intracardiac ECG Signals W. B. Buchenberg1, G. Hoppe1, R. Lorenz1, W. Mader2, P. Laudy3, C. Bienek4andB. Jung1 1Dept. ofRadiology, Medical Physics, University Medical Center, Freiburg, Germany, 2Freiburg Center for Data Analysis and Modeling, Albert-Ludwigs-University, Freiburg, Germany, 3CardioTek B.V., Maastricht-Airport, Netherlands, 4R&D, Schwarzer GmbH, Heilbronn, Germany

  2. 1 ELECTROPHYSIOLOGIC(EP) STUDIES • assess cardiac electrical system • diagnosis and therapy of EP disorders • catheter guidance: • X-ray fluoroscopic imaging disadvantages: • x-ray exposure (staff + patient) • poor tissue contrast • alternative imaging modalities: Magnetic Resonance Imaging (MRI) catheters

  3. MAGNETOHYDRODYNAMIC (MHD) EFFECT • s u r f a c e E C G s B = 0 T B ≈ 1.5 T • distortion of surface ECGs1,2,3 and intracardiac ECGs (iEGMs)4

  4. MAGNETOHYDRODYNAMIC (MHD) EFFECT induced voltage1,2: • mean flow velocity of axial symmetrical flow profile • B0 external magnetic field • d electrode distance 0 3

  5. OBJECTIVES establish experimental setup for simulating MHD signal with common clinical EP-devices • characterization of measured MHD-signal Umeas(bipolar): • magnetic field strength • electrode distance • filter settings of recording modality • comparison of Umeas with UMRI,calcfrom MR flow measurements • implementation of methods to remove MHD signals from intracardiac ECG signal (iEGMs)

  6. EXPERIMENTAL SETUP • simulateelectricalconductivityofblood: dist. H2O + NaCl 1.5 Tesla 50 bpm

  7. EXPERIMENTAL SETUP • simulateelectricalconductivityofblood: dist. H2O + NaCl 1.5 Tesla 50 bpm VAD (Ventricular Assist Device):

  8. EXPERIMENTAL SETUP • simulateelectricalconductivityofblood: dist. H2O + NaCl 1.5 Tesla 50 bpm UMHD (1) catheterpositioning:

  9. EXPERIMENTAL SETUP • simulateelectricalconductivityofblood: dist. H2O + NaCl 1.5 Tesla 50 bpm (1)

  10. EXPERIMENTAL SETUP • simulateelectricalconductivityofblood: dist. H2O + NaCl 1.5 Tesla 50 bpm (1)

  11. MRI FLOW MEASUREMENTS 2D slice

  12. RESULTS – MHD SIGNAL vs. TIME UMHD,PP

  13. RESULTS – MHD SIGNAL vs. TIME UMHD,PP

  14. RESULTS – MHD VOLTAGE vs. DISTANCE

  15. RESULTS – MHD VOLTAGE vs. MAGNETIC FIELD

  16. RESULTS – MHD VOLTAGES (2/9)

  17. RESULTS – MHD VOLTAGES high pass filtered (fcutoff = 0.05 Hz) (2/9)

  18. RESULTS – HIGH PASS FILTERS • UMHD,PP (fcut off : 0.2 Hz) ≈ UMHD,PP (fcut off : 0.05 Hz) (within ± 4%) • UMHD,PP (fcut off : 40 Hz) remaining UMHD,PP ≤ 3% • UMHD,PP (fcut off : 80 Hz) remaining UMHD,PP ≤ 2%

  19. DISCUSSION & OUTLOOK • experimental setupestablishedsuccessfully • MHD potential (bipolar measured) was characterized: • shows linear dependency on B0, d • followscharacteristicsofvelocitypattern • same orderofmagnitudeasintracardiac signals1 • MR flow data - post processing: • MHD signal reconstructed using MR velocity data • measured and calculated MHD signal agree very well • Outlook • iEGM data correction based on MR flow measurements

  20. ACKNOWLEDGEMENTS: Christoph Benk Mr. Knieriem, St. Jude Medical Mr. Simon, Mr. Baecke, seleon gmbh Grant supportbyEUROSTARS Program Grant #01QE1004D THANK YOU FOR YOUR ATTENTION!

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