1 / 19

K 305 27 June 03

K 305 27 June 03. Contractile Dysfunction. Reversible stunning hibernation Irreversible necrosis apoptosis. Contractile Dysfunction. This cell damage produces: hypocontractility enhance the likelihood of arrhythmias both of which can be lethal.

cicely
Télécharger la présentation

K 305 27 June 03

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. K 305 27 June 03

  2. Contractile Dysfunction • Reversible • stunning • hibernation • Irreversible • necrosis • apoptosis

  3. Contractile Dysfunction • This cell damage produces: • hypocontractility • enhance the likelihood of arrhythmias • both of which can be lethal

  4. Etiology of Ischemia - Reperfusion Injury • osmotic overload • number of particles in cytosol as lactate accumulates and ATP is broken down • immune response • neutrophils and complement system • pH paradox

  5. Etiology of Ischemia - Reperfusion Injury • pH paradox • ¯ pHi which increases: • Na+-H+ activity • [Na+]I • Na+-Ca2+ exchange reverse activity • [Ca2+]i overload • contractile dysfunction

  6. Regulation of Intracellular H+ • H+ extrusion (acidosis) • NHE-1 • pH paradox

  7. EKG changes with ischemia/ MI Subendocardium • results in ST segment depression • injury current at rest causes baseline elevation • during plateau causes ST segment depression • observe a J point at the point between the QRS complex and the ST segment and this point represents zero current in the heart as all parts of the ventricles are depolarized • ST segment depression is usually due to imbalance between supply and demand and will reverse when exercise is stopped during a stress test

  8. EKG changes with ischemia/ MI

  9. EKG changes with ischemia/ MI Subepicardium or transmural • immediately results in heightened T waves • may be followed by T wave inversion • T wave inversion problems with directionality of repolarization • ST segment elevation occurs due to injury current during plateau phase of the action potential which is moving towards epicardium • deep (dirty, pathological) Q waves reflect scarring

  10. EKG changes with ischemia/ MI

  11. Plasma markers of MI • 24-72 hours after MI - increases in: • CK • LDH • TnI

  12. Radionuclide Imaging of Heart • Technetium-99m-MIBI • MIBI - 2-methoxy isobutyl isonitrile • MIBI travels via CBF becomes trapped within healthy, active muscle cells in the heart • radioactivity monitored with a gamma camera • during an MI, some muscle cells will not trap the MIBI • also occurs with CAD except the lack of MIBI in some of the muscle cells is due to inadequate CBF

  13. Cardiac Ischemia

  14. Ischemic Preconditioning

More Related