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Understanding Atherosclerosis and Ischemic Heart Disease Pathophysiology

Explore the development of fibrous plaque, metabolic syndrome, and the impact of atherosclerosis on oxygen delivery in Ischemic Heart Disease. Learn about myocardial oxygen demand, manifestations of ischemia, and the risks of sudden cardiac death and strokes.

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Understanding Atherosclerosis and Ischemic Heart Disease Pathophysiology

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  1. Atherosclerosis

  2. The Arterial Wall www-ermm.cbcu.cam.ac.uk/nfig003jal.gif

  3. Cross-section of an Arterial Wall

  4. Yellow Streak

  5. http://www.surrey.ac.uk/SBMS/MicrobialSciences/research/immunology.htmlhttp://www.surrey.ac.uk/SBMS/MicrobialSciences/research/immunology.html

  6. Development of Fibrous Plaque

  7. The Metabolic Syndrome 1. Abdominal obesity (waist circumference >40 inches for men, 35 inches for women) 2. Triglyceride levels >150 mg/dL 3. HDL cholesterol <40 mg/dL for men, <50 mg/dl for women 4. Blood pressure >130>85 mmHg (normal is about 120/80) 5. Fasting blood glucose >110 mg/dL (normal is 100 mg/dL)

  8. Ischemic Heart Disease A mismatch between oxygen demand and oxygen delivery

  9. What influences O2 Delivery? • O2 carrying capacity of blood. • Coronary blood flow • Influenced by neural, endothelial and metabolic factors • Can be compromised by atherosclerosis

  10. What influences the myocardial O2 demand? • Heart Rate – Inc. HR inc. O2 demand • Cardiac contractility – Inc. contractility inc. O2 demand • Ventricular wall stress – proportional to afterload and the radius of ventricle => Law of Laplace

  11. Law of LaPlace • The ventricular wall stress (T) is the energy required to pull the cardiac muscle fibers together, so that they can contract. • Tension is proportional to the product of Intraventricular pressure (P), (which = afterload) and Radius of ventricle (R) • So, the greater the volume of the ventricle, the more energy required for contraction.

  12. What enlarges the volume of the ventricle? • A large blood volume (preload) => increase EDV, distends the ventricle • Ventricular dilation – a pathologic condition

  13. Manifestations of ischemia • Angina chest pain associated with intermittent myocardial ischemia. • Myocardial infarction (MI) is irreversible necrosis of cardiac muscle cells resulting from a prolonged period with of insufficient myocardial blood flow.

  14. http://www.smbs.buffalo.edu/pth600/IMC-Path/images/yr2/Coronary_Thrombosis_Schematic-Robbins.jpghttp://www.smbs.buffalo.edu/pth600/IMC-Path/images/yr2/Coronary_Thrombosis_Schematic-Robbins.jpg

  15. Vulnerable plaques are most likely to rupture, causing a myocardial infarction or a stroke

  16. Pathophysiology of Heart Disease 3/e. Leonard S. Lilly, Ed. Lippincott Williams and Wilkins. 2003

  17. Serum Markers of Myocardial Infarction Pathophysiology of Heart Disease 3/e. Leonard S. Lilly, Ed. Lippincott Williams and Wilkins. 2003

  18. Sudden Cardiac Death aka: Cardiac arrest • Often triggered by cardiac arrhythmia, which prevents the heart from contracting effectively. • Cause is often coronary artery disease. • Death of muscle tissue can make the heart more vulnerable to the type of arrhythmia that leads to SCD.

  19. There are two types of strokes • Ischemic or occlusive strokes, which occur when a portion of the blood flow to the brain is blocked. • Intracranial hemorrhages occur when a blood vessel in the brain ruptures.

  20. A Complete Circle of Willis Protects Against Stroke

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