13.17 - Cardiovascular Disease

Coronary heart disease

• The coronary arteries branch from the base of the aorta and run over the surface of the heart, supplying the heart muscle itself with oxygen-rich blood so it can keep contracting.
• Coronary heart disease is what happens when these arteries become blocked.

How the arteries become blocked

1. Over time, layers of fatty material build up on the inside walls of the coronary arteries.
2. This narrows the space inside them (the lumen), so blood flow through the arteries is restricted and less oxygen reaches the heart muscle.
3. The heart muscle needs a constant supply of oxygen to respire and keep working, so this lack of oxygen puts the heart under strain.

Heart attacks and strokes

• The fatty deposits can harden and damage the artery wall. A piece breaking off can trigger a blood clot.
• If a clot blocks a coronary artery completely, the heart muscle beyond the blockage is cut off from blood altogether, causing a heart attack - part of the heart muscle is starved of oxygen and its cells die.
• The same kind of blockage can happen in the blood vessels supplying the brain. There it cuts off oxygen to the brain cells, which die, resulting in a stroke, with reduced brain function.
• A number of risk factors, including smoking, raise a person's chance of developing the disease.

Risk factors for cardiovascular disease

• Coronary heart disease has no single cause - instead, a number of risk factors raise a person's chance of developing it.
• A risk factor is something linked to a greater likelihood of getting a disease, without guaranteeing it.

Lifestyle (controllable) risk factors

• A diet high in saturated fat and salt
• Smoking
• Stress
• Drinking too much alcohol
• A lack of exercise

How some of these raise the risk:

• Too much saturated fat raises the level of cholesterol in the blood.
• High cholesterol and high blood pressure both encourage fatty deposits to form in the arteries.
• Smoking raises blood pressure and damages the artery walls.

Fixed risk factors

• Getting older
• Being male rather than female
• Inheriting certain genes

Lowering the risk

Reducing the controllable factors lowers the risk of the disease:

• Eating a diet low in saturated fat and salt
• Exercising regularly
• Not smoking

Treating cardiovascular disease with lifestyle changes

• Cardiovascular disease can be treated in three broad ways: lifestyle changes, medication, and surgery.
• These are often used together, and each has its own balance of benefits and drawbacks.
• Lifestyle changes are usually tried first.

A person may be advised to:

• Eat a healthy diet low in saturated fat
• Exercise regularly
• Stop smoking

These changes lower the risk of developing the disease and form part of the treatment once someone has it.

Benefits and drawbacks

• Advantage - They have almost no harmful side effects.
• Drawback - They take a lot of self-discipline to keep up.

Drug treatments for cardiovascular disease

Two main medications are used to treat cardiovascular disease: statins and aspirin.

Statins

• Statins change the balance of cholesterol in the blood.
• They reduce the amount of 'bad' (LDL) cholesterol, which slows the build-up of fatty deposits in the arteries.
• They can raise the level of 'good' (HDL) cholesterol, which helps remove the bad type.
• Overall, this lowers the risk of heart attacks and strokes.

Drawbacks of statins:

• Must be taken regularly over years.
• They take time to work.
• They can cause side effects, ranging from headaches to liver or kidney damage.

Aspirin

• Aspirin is taken to make the blood less likely to clot, so clots are less likely to form and block an artery.
• Drawback: blood that clots less easily means a greater risk of bleeding.

Surgical treatments for cardiovascular disease

Two main surgical treatments open up a narrowed coronary artery so blood can keep flowing to the heart muscle.

Stents

• A stent is an expandable tube placed inside the artery to hold it open.
• This keeps blood flowing to the heart muscle, so the risk of a heart attack falls.
• Advantages - Stents work for a long time and recovery is fairly quick.
• Disadvantages - The operation carries the usual surgical risks, and a blood clot (a thrombosis) can form near the stent.

Angioplasty

• Angioplasty uses a small balloon, which is passed into the narrowed artery and inflated to widen it, restoring blood flow.
• Advantages - It can be the only way to clear an artery after a heart attack.
• Disadvantages - The artery can narrow again later, and as with any surgery there is a risk of bleeding, infection, and clots.