Pathogenesis of coronary heart disease:

Formation of plaque occurs by the response of dyslipidaemia. During dyslipidaemia the LDL-C accumulates in the inner layer of the artery called intima. Rigid endothelial membrane is formed over the plaque.

Pro inflammatory cytokines are released from the plaque and other inflammatory chemical and monocytes are attracted to the plaque making the inflamed plaque more inflamed and the macrophages eats cholesterol called foam cells. These all contribute to the athermateus plaque causing blockage of the luminal arteries.

Composition of atherosclerotic plaques:

· Monocytes (neutrophils and macrophages)

· Red blood cells and platelets

· Foam cells

· LDL (cholesterol, phospholipids, lipoproteins)

· Inflammatory mediators (IL, cytokines)

These all substances forms together to form an atherosclerotic plaque.

Layers of blood vessels:

There are 3 layers of the blood vessels

1. Intima (inner most layer)

2. Media (median layer)

3. Adventitia (outermost layer)

Smoking causes increase level of oxidize LDL. In diabetes mellitus the metabolism of lipid is impaired leading to atherosclerotic plaque.

What is the Function of an LDL?

Function of an LDL is transport the lipids from the intestine to the arteries (bad cholesterol).

What is the function of an HDL?

Function of HDL is transport the lipids from the arteries to the liver (good cholesterol).

Diagnosis of coronary heart disease:

· History (previous history, family history, mediation history, chronic disease history)

· Physical examination

· Angiography (fluorescence)

· Check cardiac enzymes (troponin / myoglobin) when cells break release molecules called biomarkers.

· Nuclear imaging (C11, C14, O15, technetium, gallium, I123)

· Stress test (exercise tolerance test (ETT) to find out work load.

· ECHO

· Electrocardiogram (ECG).

This is a fast and painless testing to measures the electrical activity of the heart.

· Echocardiogram.

This test is using sound waves to create pictures of beating heart.

Clinical presentation of coronary heart disease:

1. Chest pain / angina:

Angina pectoris is the main and chief symptom of coronary heart disease. If the lumen is blocked up to 50%, the perfusion of the blood is enough during rest, the pain starts only during increase nor epinephrine induced by exercise or stress as in stable angina.

If the coronary artery is blocked more than 90% it may cause pain even during in rest as in unstable angina. During unstable angina the previously formed thrombus may become amboli can occlude small arteries

What is the mechanism of pain?

Ischemia in cardio myocytes cause production of pain mediators which irritates nerve endings cause pain.

For example;

· Lactic acid

· Adenosine

· Prostaglandins

· Substance-P

· Bradykinin

Upto some extent our body produces natural pain killer

For example;

· Oxytocin

· Endorphins

To counter the pain.

How does angina pain feel?

The anginal pain may be felt as heartburn and epigastric pain.

2. dyspnoea

Dyspnoea is the shortness of breath.

3. diaphoresis

Diaphoresis is the excessive sweating.

Inflammation and release of certain mediators increase sweating increase work load of heart and release of nor epinephrine

4. dysrhythmia

Dysrhythmia is the abnormal heart condition, tachycardia is the example of dysrhythmia.

5. ECG changes:

The ST segment may be elevated.

6. Fainting

7. Rapid pulse

8. Fatigue