Download pathogenisis of coronary artery disease

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Atherosclerosis is most common cause of
coronary artery disease (CAD).
 Atherosclerosis can affect one or all
three major coronary arteries i.e. LAD,
Left circumflex, right coronary artery.
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What is Atherosclerosis?
 It is type of arteriosclerosis or hardening
of arteries.
 In Atherosclerosis, there is formation of
fibro fatty lesions in the intimal lining of
the large and medium sized arteries such
as aorta and its branches, coronary
arteries and cerebral arteries.
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Major risk factor is hypercholesteremia.
Hypercholesteremia can be due to
1. Constitutional factors
2. Life style
1. Constitutional factors (can not be changed)
such as
- increasing age
- male gender
- family history of premature coronary artery
disease
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2. Life style - Factors can be modified such
as
- obesity
- hypertension
- hyperlipidaemia
- diabetes mellitus
- cigarette smoking
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
We will see the normal structure of artery
and development of atherosclerosis.
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
Development of atherosclerotic lesion is
a progressive process involving
1. Endothelial cell injury
2. Migration of inflammatory cells
3. Smooth muscle proliferation and lipid
deposition
4. Development of atheromatous
plaque with a lipid core
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
It is divided into
1. Chronic ischemic heart disease
i. Chronic Stable Angina
ii. Variant or Vasospastic Angina also
called
prinzmetal Angina
2. Acute coronary syndrome
i. Unstable angina
ii. Myocardial infarction
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
These maybe
1. Stable or fixed plaque – causes stable
angina
2. Unstable plaque – which can rupture
and can cause platelet adhesion and
thrombus formation and can cause
unstable angina and myocardial
infarction
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Why plaque rupture occurs?
 It maybe spontaneous or triggered by
change in blood flow and vessel tension
due to
- sympathetic activity
- increased BP
- heart rate
- force of cardiac contraction
 These factors may disrupt the plaque.
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
Coronary Artery Disease – two types
1. Chronic Stable Angina
2. Variant or Vasospastic Angina also
called prinzmetal Angina
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There is chest pain or pressure sensation or
discomfort due to transient myocardial
ischemia.
 Pain in angina is usually described as
constricting, squeezing or suffocating
sensation.
 Pain is located in sub-sternal area or precordial area of chest.
 Pain may radiate to left shoulder, jaw, left
arm (inner side) or epigastric region.

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
Pain is associated with fixed coronary obstruction,
usually pathology is atherosclerosis.

Stable Angina is provoked by exercise, emotional
stress and is relieved within minutes (5-10mins) by rest
or use of nitroglycerine sublingually.

Precipitating factors for pain
- physical exertion
- exposure to cold
- emotional stress
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Variant angina is due to spasm of
coronary artery.
 Cause is not completely understood but
maybe due to
- Endothelial dysfunction
- Hyperactive sympathetic response
- Defective handling of Calcium by
vascular smooth muscle
- Altered Nitric acid production
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
Variant Angina occurs at rest or with
minimal exercise (stable angina occurs
at exercise).

ECG shows Transient ST-elevation .
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Diagnosis and Treatment
 Take detail history of pain (rule out non
coronary causes e.g. esophageal reflux
or musculo skeletal disorder)
 Look for risk factors e.g. hypertension,
DM, obesity, hyperlipidemia, smoking
 Laboratory test
- Noninvasive studies
- Invasive studies
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Noninvasive Test
 ECG
 X-ray chest
 Exercise stress test
 Echo cardiography
 Nuclear imaging studies
 CT and MRI
Invasive Test
 Coronary Arteriography
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Treatment
1. Non-pharmacological
2. Pharmacological
3. Coronary intervention
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Treatment
- Non-pharmacological
 Life style modification
 Stop smoking
 Stress reduction
 Regular exercise
 Weight reduction if obesity
 Decrease dietary intake of cholesterol
 Avoid cold (it produces vasoconstriction)
 If angina – sit down and rest
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Treatment
- Pharmacological
 Nitrates
 Beta-blockers
 Calcium channel blockers
 Aspirin
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Treatment
- Coronary intervention
 PCI – Percutaneous Coronary Intervention
i.e.
-Angioplasty
-Stent
- Surgery
Coronary artery bypass graft (CABG)
Surgery is indicated in patient with double
or
triple vessel disease
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
ACS includes
- unstable angina
- acute myocardial infarction
- Non ST elevation MI
- ST elevation MI
- ACS is classified based on presence or
absence of ST-segment changes on the
ECG
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- Serum biomarkers are used to determine
whether Myocardial infarction has occured
- Serum makers done in ACS are
-- Cardiac Troponin I [TnI] & Troponin T (TnT)
-- Myoglobin
-- Creatinine Kinase MB (CK-MB)
- As myocardial cell become necrotic in MI,
their intracellular content diffuse in interstial
fluid and blood
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IMPORTANT

Troponin I and Troponin T are the most
sensitive and highly specific for
myocardial infarction
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Pain in unstable angina occurs at rest or
with minimal exertion
 Pain lasts for more than 20mins
 Unstable angina is risk for MI
 Serum markers are not increased
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MI is also known heart attack.
 There is ischemic death of myocardial
tissue.
 ECG shows ST-elevation
 Area affected depends on which
coronary artery is blocked
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Clinical Presentation
 Chest pain which is sudden and severe,
retrosternal
 Character of pain – crushing,
constricting, suffocating or as some one
sitting on the chest
 Pain is retrosternal but may radiate to left
arm (inner side), neck, or jaw or
epigastrium.
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Pain and sympathetic stimulation
combine to give rise to tachycardia,
anxiety, restlessness
 Sudden death can occur in Acute MI,
within one hour of symptoms
 Cause of death ventricular fibrillation,
ventricle pump failure.
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Relieve pain e.g. Morphine
ECG 12 lead – also monitor ECG
Oxygen
Aspirin – anti-platelet
Nitrates - vasodilator
Anti-coagulent
ACE I
IMPORTANT
Look for candidates for reperfusion therapy
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It includes PERCUTANEUS TRANSLUMINAL
CORONARY ANGIOPLASTY (PTCA) with
inflatable balloon.
 Stent implantation
 Stents are of two types
- Non-drug eluting
- Drug eluting – they provide delivery of
anti-platelet agents and decrease the risk
of restenosis and their results are better than
Non- drug eluting stents.
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Surgery is done to bypass the obstructed
coronary blood vessel.
 Graft are used from
1. Saphenous vein
2. Internal Mammary artery

NOTE – Surgery is done for patients with
coronary artery disease who do not
respond to medical treatment or not
suitable for PCI
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