pathophysiology of coronary artery disease l.
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Pathophysiology of Coronary Artery Disease. Blood supply to the heart. Coronary Blood Flow : Constant Demand Arteries & veins are located on the surface of the heart, lying within groves called sulci Blood flows through coronaries during the RELAXATION phase (diastole) Why?.

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blood supply to the heart
Blood supply to the heart
  • Coronary Blood Flow: Constant Demand
  • Arteries & veins are located on the surface of the heart, lying within groves called sulci
  • Blood flows through coronaries during the RELAXATION phase (diastole) Why?
primary superficial arteries
Primary Superficial Arteries
  • Right Coronary
  • Right Marginal Branch
  • Left Coronary
  • Left Anterior Descending
  • Left Circumflex
areas of coronary artery perfusion
Areas of Coronary Artery Perfusion:
  • LAD: Majority of the left ventricle: Anterior/Inferior
  • Circumflex (Cx):Inferior and Posterior LV
  • RCA: RV, Posterior and Septal
slide8

RCA

Rt. Marginal

step 1 endothelial injury
Step 1: Endothelial Injury
  • Location? coronaries, carotids, renal arteries, lower extremities
  • Tunica Intima damaged (How?)
  • LDL Oxidation: Initiates Inflammatory Process:
  • Monocytes: Attracted and “glued” to endothelium by “ELAMS” (endothelial-leukocyte adhesion molecules)
step 2 inflammation gone haywire
STEP 2: Inflammation gone Haywire
  • Monocytes/Leukocytes enter the Sub-endothelial space
  • Initiate Smooth Muscle Cell proliferation
  • Attract more LDL to create a “fatty streak”
slide12

Ouch!

Blood Clot

Normal

Narrowed

Occluded

ldl s and atherosclerosis
LDL’s and Atherosclerosis
  • Oxidized LDLs act as a “free radical”, which induces endothelial injury inflammation begins
  • Some LDLs are removed by macrophages, but high LDLs will cause much injury
  • LDLs = accelerated atherosclerosis
slide14

Vessel

Lumen

Smooth

Muscle

myocardial oxygen supply
Myocardial Oxygen Supply
  • Cardiac cells extract most of the oxygen delivered (high A-vO2 diff)
  • Thus additional oxygen can only be met by delivering more blood by the coronary arteries
  • A reduction in coronary artery lumen size attenuates blood flow
blood flow
Blood Flow
  • Big reduction beyond 75% occlusion
  • Severity of disease depends on # of occluded arteries
  • Also location of occlusion (left coronary vs apical)
myocardial o2 demand mvo 2 depends on
Myocardial O2 demand (MVO2) depends on..
  • Myocardial tension (pressure x volume)
  • Inotropic State (Measure?)
  • Chronotropic state (Measure?)
  • Myocardial mass
indirect measure of mvo 2
Indirect measure of MVO2
  • Rate pressure product (a.k.a. double product, tension-time index)
  • Considers 2 of the MVO2 indices:
    • HR X SBP
  • Good estimate of oxygen use by the heart.
  • Used to determine angina threshold
end results of atherosclerosis

End Results of Atherosclerosis

Unstable Angina

Stable Angina

Acute Myocardial Infarction

Sudden Cardiac Death

stable angina
Stable Angina
  • Angina occurs at a consistent and predictable level of MVO2
  • Reduced Coronary Blood Flow
  • Always exercise at an intensity below the angina threshold
  • How would you identify the angina threshold?
anginal symptoms
Anginal Symptoms
  • Varied: Chest pressure/heaviness
  • Back, neck, shoulder ache
  • Diaphoresis
  • Pallor
  • Dyspnea
  • Does it occur upon exertion?
unstable angina
Unstable Angina
  • Due in part to intra-coronary spasm
  • This reduces lumen diameter
  • May occur ANY time (unpredictable) and at any work intensity
  • Termed “Vasospastic” or “Prinzmetal’s Angina”
acute myocardial infarction
Acute Myocardial Infarction
  • Intra-lumenal thrombus formation
  • Thrombus lodges in coronary artery, stops blood flow
  • Cells downstream are starved of O2
  • Leads to tissue necrosis
slide25

LAD:

Thrombosis

Area of

Infarct

sudden death
Sudden Death
  • May be due to the death of heart tissue from large vessel occlusion
  • or.. emboli (ischemia) induce ventricular arrhythmias that will kill

(i.e. ventricular fibrillation)

infarction symptoms
Infarction symptoms
  • Similar to angina: diaphoretic, pallor complexion, pain
  • Vomiting, dyspnea
  • Symptoms are often ignored or denied by the patient
  • Odds of survival are greatest if they get help within 1 hour
complications of mi
Complications of MI
  • Cardiac Tamponade: Fluid between pericardium/myocardium
  • Pericarditis: Inflammation of the pericardium
  • Emboli: From either MI thrombus or atrial clots formed with atrial pooling
most common complications
Most Common Complications:
  • Congestive Heart Failure:
    • 75% of MI’s experience overt CHF Fluid backs up…
    • 25% of MI’s experience “compensated” CHF reduced perfusion to “vital organs”?
  • Dysrhythmias:The importance of ECG monitoring post-MI
assignment
Assignment:
  • Read: “Cardiovascular disease and the endothelium”
  • Answer: How does understanding the mechanism of the disease (pathophysiology) improve prevention, detection and intervention strategies?