PATHOGENISIS OF CORONARY ARTERY DISEASE

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PATHOGENISIS OF CORONARY ARTERY DISEASE

LECTURE 2Dr. Zahoor Ali Shaikh

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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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NORMAL STRUCTURE OF ARTERY

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TYPES OF LIPOPROTEINS

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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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Development of Atherosclerosis

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What is Atherosclerotic plaque? Atherosclerotic plaque consist of

aggregation of smooth muscle cells, macrophages, leukocytes, collagen and lipids

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Site of atherosclerosis

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CORONARY ARTERY DISEASE

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CORONARY ARTERY DISEASE

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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ATHEROSCLEROTIC LESIONS IN CORONARY ARTERIES

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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UNSTABLE PLAQUE

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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CHRONIC ISCHEMIC HEART DISEASE

Coronary Artery Disease – two types 1. Chronic Stable Angina 2. Variant or Vasospastic Angina also

called prinzmetal Angina

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1- Chronic Stable Angina

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 pre-cordial area of chest.

Pain may radiate to left shoulder, jaw, left arm (inner side) or epigastric region.

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1- Chronic Stable Angina

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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2- VARIANT OR VASOSPASTIC OR PRINZMETAL ANGINA

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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2- VARIANT OR VASOSPASTIC OR PRINZMETAL ANGINA

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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Treatment1. 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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II. ACUTE CORONARY SYNDROME [ACS]

ACS includes 1- unstable angina 2- acute myocardial infarction - acute MI may be NSTEMI or STEMI - ACS is classified based on presence or absence of ST-segment changes on the ECG

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ACUTE CORONARY SYNDROME [ACS]

- 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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ACUTE CORONARY SYNDROME [ACS]

IMPORTANT

Troponin I and Troponin T are the most sensitive and highly specific for myocardial infarction

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UNSTABLE ANGINA

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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MYOCARDIAL INFARCTION [MI]

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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TREATMENT IN ACUTE CORONARY SYNDROME

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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PERCUTANEUS CORONARY INTERVENTION

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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CORONARY ARTERY BYPASS SURGERY (CABG)

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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THANK YOU

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PATHOGENISIS OF CORONARY ARTERY DISEASE

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