Imaging Electrical Activity of the Heart Özlem Özmen Okur BM573 CARDIOVASCULAR IMAGING Student Presentation

Imaging Electrical Activity of the Heart2/21 Contraction of a Cardiac Muscle Cell In the heart: Iionic current triggers the rhythmic muscle contractions that pump blood in and out.

Imaging Electrical Activity of the Heart3/21 The Different Waveforms for Each of the Specialized Cells

Imaging Electrical Activity of the Heart4/21 Need for Mapping of Electrical Activity To understand the mechanisms responsible for the normal cardiac rhythm and for the initation and maintenance of arrhythmias.

Imaging Electrical Activity of the Heart5/21 Problems (1)  Normal Sinus Rhythm (: All complexes normal, evenly spaced Rate /min  Sinus Bradycardia: All complexes normal, evenly spaced Rate < /min  Sinus Tachycardia: All complexes normal, evenly spaced Rate > 100/min  Sinus Arrythmia: All complexes normal, rhythm is irregular

Imaging Electrical Activity of the Heart6/21 Problems (2)  WANDERING PACEMAKER (Impulses originate from varying points in atria): Variation in P-wave contour, P-R and P-P interval and therefore in R-R intervals  ATRIAL FLUTTER (Impulses travel in circular course in atria): Rapid flutter waves, ventricular response irregular  ATRIAL FIBRILLATION (Impulses have chaotic, random pathways in atria): Baseline irregular, ventricular response irregular  VENTRICULAR FIBRILLATION Chaotic ventricular depolarization

Imaging Electrical Activity of the Heart7/21 Wave pattern (a single spiral) on the ventricular surface, during monomorphic tachycardia

Imaging Electrical Activity of the Heart8/21 Surface View of Fibrillation

Imaging Electrical Activity of the Heart9/21 Imaging Electrical Activity of the Heart  Reconstruction from internally located electrodes  Electrocardiographic Imaging  Optical Imaging  Magnetocardiographic Imaging

Imaging Electrical Activity of the Heart10/21 Ventricular Jacket Array Vahlhaus, Christian, et al; “Direct epicardial mapping predicts the recovery of left ventricular dysfunction in chronic ischaemic myocardium”; European Heart Journal; v. 25; n. 2; pp ; 2003.

Imaging Electrical Activity of the Heart11/21 Internally Located Defibrillation Electrodes  Left: anterior, right: posterior view of the heart and the major vessels of the heart.  Red: regions of large current densities  Blue: regions of relatively lower current densities.

Imaging Electrical Activity of the Heart12/21 Electrocardiographic Imaging  Noninvasive  Using body surface measurements  Reconstruction on the heart's surface using geometrical information from computed tomography (CT) and a mathematical algorithm. Burnes, John, et al; "A Noninvasive Imaging Modality for Cardiac Arrhythmias"; Nature Medicine; n. 10; pp ; Burnes, John, et al; "A Noninvasive Imaging Modality for Cardiac Arrhythmias"; Nature Medicine; n. 10; pp ; 2004.

Imaging Electrical Activity of the Heart13/21 Optical Imaging of Electrical Activity in the Heart Cardiac action potentials are recorded using voltage-sensitive dyes to monitor Cardiac action potentials are recorded using voltage-sensitive dyes to monitor cellular potential, cellular potential, cell to cell interactions, and cell to cell interactions, and propagation and repolarization "patterns" propagation and repolarization "patterns" underlying cardiac arrhythmias.

Imaging Electrical Activity of the Heart14/21 Optical Properties of Membrane-Bound Dyes That Have Been Used to Measure Membrane Potential Changes   Fluorescence,   Absorption,   Dichroism,   Birefringence,   Fluorescence resonance energy transfer,   Nonlinear second harmonic generation, and   Resonance Raman absorption. considerably less sensitive to movement artifacts generated by muscle contractions Efimov, Igor, et al; "Optical Imaging of the Heart"; Circ. Res.; n.95; pp ; 2004.

Imaging Electrical Activity of the Heart15/21 Schematics of a Typical Optical Mapping System

Imaging Electrical Activity of the Heart16/21 Mapping of Activation and Repolarization

Imaging Electrical Activity of the Heart17/21 Magnetocardiographic Imaging Magnetocardiographs taken from the front and back of the heart. Using a special magnetic sensor called SQUID (8100 fT to severeal tens of pT is emitted from the heart) While clothed.

Imaging Electrical Activity of the Heart18/21 Ischemic Heart Disease Example

Imaging Electrical Activity of the Heart19/21 Magnetocardiographic 3-D Visualization of Heart Current Distribution

Imaging Electrical Activity of the Heart20/21 References  Burnes, John, et al; "A Noninvasive Imaging Modality for Cardiac Arrhythmias"; Nature Medicine; n. 10; pp ;  Vahlhaus, Christian, et al; “Direct epicardial mapping predicts the recovery of left ventricular dysfunction in chronic ischaemic myocardium”; European Heart Journal; v. 25; n. 2; pp ;  Efimov, Igor, et al; "Optical Imaging of the Heart"; Circ. Res.; n.95; pp ;       

Imaging Electrical Activity of the Heart21/21 Thank You...