3. heart patghology; ischemic heart diseases

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3. heart patghology; ischemic heart diseases

  1. 1. Heart - Pathology Ischemic Heart Disease  Hypoxemia (diminished transport of oxygen by the blood) less deleterious than ischemia  Also called coronary artery disease (CAD) or coronary heart disease  IHD =Syndromes late manifestations of coronary atherosclerosis  Cause => 90% of cases, coronary atherosclerotic arterial obstruction 1 Dr. Krishna Tadepalli, MD, www.mletips.com
  2. 2. Heart - Pathology Ischemic Heart Disease  Classification = mainly 4 types Myocardial infarction (MI) Sudden cardiac death Angina pectoris Chronic IHD with heart failure  Acute Coronary syndromes important predisposing factor -Plaque disruption or Acute plaque change Acute myocardial infarction Unstable angina Sudden cardiac death 2 Dr. Krishna Tadepalli, MD, www.mletips.com
  3. 3. Heart - Pathology Ischemic Heart Disease  75% stenosis = symptomatic ischemia induced by exercise  90% stenosis = symptomatic even at rest  Pathogenesis  ↓ coronary perfusion relative to myocardial demand  Role of Acute Plaque Change (Erosion/ulceration, Hemorrhage into the atheroma, Rupture/fissuring, Thrombosis)  Role of Inflammation T cell, Macrophages (MMPs), CRP  Role of Coronary Thrombus The most dreaded complication  Role of Vasoconstriction (VC) Platelet & Endothelial factors, VC substances 3 Dr. Krishna Tadepalli, MD, www.mletips.com
  4. 4. Heart - Pathology 4 Dr. Krishna Tadepalli, MD, www.mletips.com
  5. 5. Heart - Pathology Plaque Disruption Syndrome Stenoses Plaque-Associated Thrombus Stable angina >75% No No Unstable angina Variable Frequent Non-occlusive Transmural MI Variable Frequent Occlusive Subendocardial MI Variable Variable Widely variable Sudden death severe Frequent Often small 5 Dr. Krishna Tadepalli, MD, www.mletips.com
  6. 6. Heart - Pathology Ischemic Heart Disease  Angina Pectoris  Chest discomfort = prolonged, recurrent, different qualities  Cause = transient myocardial ischemia( seconds to minutes)  Patterns Stable = 75% vessel block, transient ( <15 minutes), aggravated by exertion, relived by rest & Nitroglycerin (VD) Prinzmetal = coronary spasm, episodic, Typical EKG change – ST elevation, Relived by VD but not rest Unstable = 90% vessel block or Acute plaque change ( superimposed thrombus), prolonged ( >15 min.), not relived by rest, VD, Pre-infarction Angina 6 Dr. Krishna Tadepalli, MD, www.mletips.com
  7. 7. MI - Types Transmural  Full thickness  Superimposed thrombus in atherosclerosis  Focal damage Sub-endocardial  Inner 1/3 to half of ventricular wall  Decreased circulating blood volume( shock, Hypotension, Lysed thrombus)  Circumferential 7 Dr. Krishna Tadepalli, MD, www.mletips.com
  8. 8. Heart - Pathology Ischemic Heart Disease  MI= Also called Heart attack  Incidence = disease of old  elderly (45% in 65 yrs. old)  young ( 10% in 40yrs. Old),  Sex = Male > Female  Ethnic = same in African & American  Risk factors  Major modifiable- DM, HTN, Smoking, Hypercholesterolemia  HRT for Postmenopausal females – will not protect the heart 8 Dr. Krishna Tadepalli, MD, www.mletips.com
  9. 9. Heart - Pathology Ischemic Heart Disease  MI  Pathogenesis  Coronary vessel occlusion Atherosclerosis with thrombus = MC cause ( 90% cases) Others = vasospasm (10%)  Most important mechanism = dynamic changes in the plaque (rather than plaque size),  Plaque disruption PLTS aggregation thrombus and VC (happens in minutes)  Irreversible changes = after 30 minutes of ischemia ATP < 10% of normal  Mechanism of cell death = necrosis ( Coagulative) 9 Dr. Krishna Tadepalli, MD, www.mletips.com
  10. 10. Heart - Pathology Ischemic Heart Disease TTC 10 Dr. Krishna Tadepalli, MD, www.mletips.com
  11. 11. Heart - Pathology Ischemic Heart Disease  MI -Morphology  light microscopy  First 12 hrs. after MI – no change  Up to 3 days = Coagulative necrosis, neutrophils  1-2 weeks = Granulation tissue  ≥ 3 weeks = fine scar  ≥ 2 months = dense scar  EM – membrane disruption and Mitochondrial densities  Special stain = TTC ( Triphenyl Tetrazolium chloride),  Detects and stains Mahogany brown with Lactate dehydrogenase  Unstained area = infarction  Mahogany brown = viable  White, glistening= scar  Most common and nonspecific change in ischemia = subendocardial myocyte vacuolization 11 Dr. Krishna Tadepalli, MD, www.mletips.com
  12. 12. MI- Microscopic features One-day-old infarct Up to 3 days duration wavy fibers coagulative necrosis 1 -2 weeks Granulation tissue Neutrophilic infiltrate >3 weeks Scar 12 Dr. Krishna Tadepalli, MD, www.mletips.com
  13. 13. Heart - Pathology Ischemic Heart Disease  MI –Reperfusion  Mechanisms  Intrinsic  Extrinsic = Thrombolytic drugs = < 1hr. After onset of MI PTCA/CABG = > 1hr. After onset of MI  Target = clot lysis and restoration of blood flow  Post- reperfusion changes =  Contraction bands = hyper contracting myocytes,  Stunned myocardium = transient, protective dysfunction  Reperfusion damage = mostly apoptosis by free radicals ( unlike MI) 13 Dr. Krishna Tadepalli, MD, www.mletips.com
  14. 14. Heart - Pathology Ischemic Heart Disease 14 Dr. Krishna Tadepalli, MD, www.mletips.com
  15. 15. Heart - Pathology Ischemic Heart Disease  MI = Clinical  Silent MI = DM, Elderly, Cardiac transplantation recipients,  Typical features = Rapid, weak pulse and sweating profusely (diaphoretic), Dyspnea, chest pain  Lab=  Diagnostic Best markers = Troponins ( T & I), both sensitive and cardio – specific Next best – CK-MB  Predictive CRP- >3mg/l – highest risk 15 Dr. Krishna Tadepalli, MD, www.mletips.com
  16. 16. Heart - Pathology Ischemic Heart Disease MI –Complications   In 75% of Patients with MI Poor prognosis in = elderly, females, DM, old case of MI, Anterior wall infarct – worst, posterior –worse, Inferior wall – best  1. Arrhythmia = Ventr. Fibrillation – MC arrhythmia lead to sudden death in MI patients, before they reach hospital  2. pump failure – LVF, cariogenic shock, if >LV wall infarcts, lead to death ( 70% of hospitalized MI patients)  3.Ventricular rupture = Free or lateral LV wall – MC site, later cause false aneurysm,  4.True aneurysm = rupture is very rare  5.Pericarditis = Dressler’s syndrome ( Late MI complication)  6.Recurrence 16 Dr. Krishna Tadepalli, MD, www.mletips.com
  17. 17. Heart - Pathology Ischemic Heart Disease  Sudden cardiac death = unexpected death in one hour due to cardiac causes with or without clinical symptoms  Cause – Atherosclerosis ( 90%), others (10%)  Romano- Ward syndrome – Long Q-T syndrome ( K+, Na+ channel defects)  Mechanism- Most likely due to arrhythmias ( VF)  Patients – young athletes, with Pul. HTN, IHD  Morphology  Prominent finding – increased heart mass  Vacuolations in Sub – endocardial myocardium 17 Dr. Krishna Tadepalli, MD, www.mletips.com
  18. 18. Heart - Pathology Ischemic Heart Disease  Chronic IHD = also called ischemic cardiomyopathy  Patients = post heart transplant receipts, previous MI or CABG pts  Cause =compromised ventricular function  Morphology =vacuoles, Myocyte Hypertrophy  Diagnosis= by exclusion 18 Dr. Krishna Tadepalli, MD, www.mletips.com
  19. 19. Heart - Pathology What is it? 19 Dr. Krishna Tadepalli, MD, www.mletips.com
  20. 20. Heart - Pathology What are these? 20 Dr. Krishna Tadepalli, MD, www.mletips.com

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