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CVS M2 > Ischemic Heart Disease > Flashcards

Ischemic Heart Disease Flashcards

1
Q

What is ischemic heart disease?

A

Spectrum of disorders due to imbalance between myocardial metabolic demands and coronary blood flow

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2
Q

What are the underlying causes of ischemic heart disease?

A
  1. Atherosclerosis
  2. Embolism
  3. Ostial Stenosis in Syphilitic Aortitis
  4. Dissecting Aneurysms
  5. Direct Trauma
  6. Arteritis
  7. Anomalous origin of LCA
  8. Hypoxemia - anemia, CO poisoning, hypotensive crises
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3
Q

What is the pathogenesis of ischemic heart disease?

A
  1. Reduced Coronary Flow
    - 75% occlusion of coronary artery lumen
  2. Increased myocardial demand
    - exercise, infection, pregnancy, hyperthyroidism, myocardial hypertrophy
  3. Availability of oxygen in blood
    - anemia, CO poisioning, pulmonary disease, left to right shunt
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4
Q

Describe an atherosclerotic plaque in typical angina.

A

Stable plaque. Fibrous component is predominant, smaller necrotic component

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5
Q

How can a stable plaque in fixed coronary obstruction progress?

A
  1. Plaque gradually expands and compromises lumen – severe fixed coronary obstruction (chronic ischemic heart disease)
  2. Plaque disruption (plaque rupture, clot forming); this plaque disruption can heal into severe fixed coronary obstruction OR result in mural thrombus or occlusive thrombus
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6
Q

What condition does a patient have if a mural thrombus forms?

A

Unstable angina, or acute subendocardial myocardial infarction

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7
Q

What condition would a patient have if a occlusive thrombus forms?

A

Acute transmural MI or sudden death

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8
Q

Talk about an unstable plaque.

A

Most clinically dangerous.
Often smaller plaques.
Large lipid core, thin fibrous cap.
Likely to fissure, rupture, ulcerate and plaque hemorrhage

Larger and often more occlusive plaques may be more stable (smaller lipid core and more fibrous tissue)

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9
Q

What are 4 clinical manifestations of ischemic heart disease?

A
  1. Angina Pectoris
  2. Myocardial Infarction
  3. Chronic Ischemic Heart Disease with Heart Failure (progressive heart failure consequent to previous MI)
  4. Sudden cardiac death
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10
Q

What is angina?

A

Episodic chest pain on exertion, caused by transient ischemia of the myocardium, relieved by rest or vasodilators (GTN)

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11
Q

What are symptomatic patterns of angina?

A
  1. Stable Angina
  2. Prinzmental Angina
  3. Unstable Angina
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12
Q

What is stable angina?

A
  1. Stable atherosclerotic plaque
  2. Myocardial demand is greater than coronary perfusion
  3. Relieved by rest of vasodilator
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13
Q

What is prinzmental angina?

A
  1. Uncommon form of episodic myocardial ischemia
  2. Due to arterial spasm, unrelated to physical activity, heart rate or blood pressure
  3. Responds to vasodilators
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14
Q

What happens in unstable angina?

A
  1. Disruption of atherosclerotic plaque, complicated by partially occlusive thrombosis and vasoconstriction
  2. Leads to severe but transient reductions in coronary blood flow
  3. Increasingly frequent pain, prolonged duration, precipitated by lower levels of activity
  4. Increased risk of MI; 5-8% die in 6months
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15
Q

What is myocardial infarction?

A

Death of cardiac muscle following impaired blood flow

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16
Q

Types of MI?

A
  1. Regional MI (90%)
    - Thrombus on complicated atheroma
    - Full Thickness (Regional Transmural MI) – ST Elevation
    - Partial Thickness (Regional Subendocardial MI) – ST Depression
  2. Circumferential Subendocardial Infarction (10%)
    - general hypoperfusion caused by hypotension
17
Q

Who is at risk of MI?

A

Men, post menopausal women

18
Q

What is the pathogenesis of MI?

A

Typical (90%):
- acute plaque event (atherosclerosis)
- thrombus formation
- complete occlusion of lumen
*ATP decrease, lactic acid increase; because myocytes are very oxygen dependent, induces loss of contractility as soon as 60s; if lasts more than 30min = irreversible damage

10% (absence of coronary vascular pathology):
- vasospasm: cocaine abuse
- emboli
- ischemia without atherosclerosis/thrombi
– vasculitis, shock, vascular dissection, amyloidosis, infective endocarditis vegetation

19
Q

Which area of myocardium is most prone to infarction?

A

Subendocardial layer, extending outwards

20
Q

What is areas of the heart are affected when the LAD is blocked?

A
  1. Anterior wall of LV near apex
  2. Anterior 2/3 of IV septum
21
Q

What areas of the heart are affected when the RCA is blocked?

A
  1. Inferior/posterior wall LV
  2. Posterior 1/3 of IV septum
  3. Posterior RV wall
22
Q

What areas of the heart are affected when the LCA is blocked?

A

Lateral Wall LV

23
Q

What are the proportions of MI in LAD, RCA, LCA?

A

LAD - 40-50%
RCA - 30-40%
LCA - 15-20%

24
Q

What are clinical signs and symptoms of MI?

A
  1. Symptoms: Severe, Crushing Chest Pain
  2. ECG Changes
  3. Elevated Cardiac Enzymes (Troponin)
25
Q

Describe the morphology of MI at
a) 0-12h
b)12-24h
c) 24-72h
d) 3-10d
e) 6-8weeks

A

a) macroscopically and microscopically not visble; do triphenyl tetrazolium chloride test (infarcted area is pale)

b) macroscopically - pale with blotchy discoloration; histologically - infarcted muscle brightly eosinphilic, loss of nucleus, intercellular edema, myocytolysis (large vacuolar spaces present within myocytes, identified because of edema around them)

c) macroscopically: pale and soft, yellow; histologically - neutrophil infiltration, wavey because alive myocytes pull on the dead fibres

d) macroscopically: hyperaemic border around yellow area; histologically: granulation tissue response on the border of necrotic areas (later becomes fibrosis)

e) fibrous scar

26
Q

What are 4 complications of MI

A
  1. Ventricles
    - LV failure = congestive heart failure
    - ruptured myocardium = cardiac tamponade or adhesion to pericardial sac due to inflammation
    - fibrosis and aneurysm (false wall/false aneurysm OR true aneurysm ‘outpouching’ prone to thrombus formation
    - thrombus formation = emboli
  2. Conduction System
    - arrythmias (because myocardium is irritable, tgt with areas of necrosis & fibrosis = conduction disturbances
    – VF, ventricular tachycardia, bundle of his (heart block)
    * can lead to sudden cardiac death
  3. Pericarditis - 2-3days after
  4. Valves
    - ruptured papillary muscle due to necrosis = valvular regurgitation
27
Q

What happens in chronic ischaemic heart disease?

A
  1. Chronic atherosclerotic narrowing of coronary arteries
  2. Slow loss of myocardial fibres
  3. Generalised myocardial fibrosis
  4. Insidious cardiac failure = death
28
Q

What happens in sudden cardiac death?

A
  1. Lethal arrythmias - VF
  2. Pronounced stenosis of 1 or more of major arteries
  3. Acute plaque changes

CVS M2 (10 decks)

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