Coronary artery disease (CAD) occurs when the arteries that supply blood to the heart muscle (the coronary arteries) become hardened and narrowed. The arteries harden and narrow due to build-up of fatty deposits called plaque on their inner walls. The build-up of plaque is known as atherosclerosis. As the plaque increases in size, the insides of the coronary arteries get narrower and less blood can flow through them. Eventually, blood flow to the heart muscle is reduced and can cause chest pain (angina). A sudden, complete blockage can lead to a heart attack.

Many people with this disease are not aware they have it, as it develops slowly and silently over decades. It can go virtually unnoticed until it produces a heart attack.

Causes and symptoms
Coronary artery disease (CAD) is caused by atherosclerosis or hardening of the arteries due to old age.

In atherosclerosis, plaque build-up in the arteries is made up of fat, cholesterol, calcium, and other substances from the blood.

Plaque build-up in the arteries often begins in childhood. Over time, plaque build-up in the coronary arteries can:
• narrow the arteries, reducing the amount of blood and oxygen reaching the heart muscle,
• block the arteries completely which stops the flow of blood to the heart muscle,
• cause blood clots to form which can block the arteries that supply blood to the heart muscle.

The figure above shows a normal artery with normal blood flow and an artery containing plaque build-up.

CAD varies in signs and symptoms and in severity.
• No symptoms - Referred to as silent ischaemia, you do not have any symptoms although blood supply to your heart may be restricted.
• Chest pain (Angina) - Usually brought about by physical or emotional stress. It feels like a heavy weight on your chest.
• Shortness of breath - Occurs when the heart fails due to damage of heart muscles.
• Heart attack - Caused by a blood clot or rupture in a narrowed coronary artery. The part of the heart muscle fed by that artery dies. Pain from a heart attack is often described as a crushing pain and may feel similar to angina, but lasts longer.

Detection
Diagnosis normally starts with a physical examination, taking of your medical history and routine blood tests. Other tests recommended may include:
• Electrocardiogram (ECG)
• Exercise Stress Test
• Coronary Angiography
• Echocardiogram
• CT Coronary Angiography

Treatment
You can prevent or slow down coronary artery disease by improving the health of your heart and blood vessels.

Drugs and surgical techniques can open up narrowed coronary arteries. Making lifestyle choices to control the risk factors for coronary artery disease is the best long-term measure.

While many people are able to manage this disease with lifestyle changes and medications, others with severe coronary artery disease may need coronary angioplasty or surgery.

There are various procedures to improve coronary blood flow (revascularisation).
1. Percutaneous coronary intervention
A common treatment for severe blockage of the coronary arteries, it is also known as coronary or balloon angioplasty / percutaneous transluminal coronary angioplasty (PTCA) with coronary stent placement.

In PTCA, a small balloon or stent is used to help keep the part of the artery that is blocked open. The latest option within PTCA is the use of drug-eluting stents, which are stents covered with a drug, which supposedly has been shown to reduce the rate of re-narrowing of the arteries.

If percutaneous coronary intervention does not widen the artery or if complications occur, you may need coronary artery bypass surgery.

2. Coronary artery bypass surgery
This is an open heart surgery where a route is created for blood to go around a blocked part of a coronary artery to supply your heart with enough blood to relieve chest pain.

Valvular heart disease is a disorder or disease of the heart valves, which are the tissue flaps that regulate the flow of blood into and out of the chambers of the heart.

Patients with valvular heart disease have a malfunction of one or more of the heart valves. There are several types of valvular heart diseases with distinct symptoms and treatment options.

Problems with heart valves may occur as a result of infections (most commonly infective endocarditis and rheumatic fever), degeneration, or congenital abnormality.

Patients who have developed the disease may report fever, fatigue, night sweats, chills, and joint inflammation.

The symptoms of rheumatic fever include fever, joint pains, and either lumps under the skin or raised red patches on the skin.

Treatment
The treatment of specific valvular heart disease will vary, depending on the valve involved and the extent of damage or malfunction. Some patients will not require any specific treatment and many can be treated with medications. Sometimes, patients need surgery. If multi-valvular disease is suspected, the different valves may be evaluated during surgery on one of the affected valves. Women with heart valve disease and want to become pregnant should receive a thorough check-up and see a cardiologist regularly throughout their pregnancy.

Infective endocarditis - Depending on the type of bacterium that caused the disease, an appropriate antibiotic or combination of antibiotics will be used to treat infective endocarditis. Severe cases may be corrected by valve replacement surgery.

Rheumatic fever - Patients with rheumatic fever will be treated with antibiotics to eliminate streptococcal organisms that may still remain in the heart. Patients may receive antibiotics to prevent further infection, and inflammation may be treated with aspirin or cortisone-like drugs. 

Arrhythmias refer to any change in the normal sequence of electrical impulses produced by the heart. The abnormal heart rhythms can be slow or fast, have an extra beat, or otherwise beats irregularly.

Age increases the probability of experiencing an arrhythmia. It can occur in people who do not have heart disease. Arrhythmias often occur during and after heart attacks.

Some types of arrhythmias, such as ventricular tachycardia, are serious and even life threatening.

Arrhythmias are the primary cause of sudden cardiac death, accounting for more than 200 deaths each year in Singapore.

Slow heart rates (less than 60 beats per minute) are called bradycardias. It can result in poor circulation of blood with resulting lack of oxygen throughout the body, especially the brain.

Fast heart rates (more than 120 beats per minute) or tachycardias compromise the heart's ability to pump effectively.

Supraventricular Arrhythmia is less serious, and Ventricular Fibrillation is the most serious type of arrhythmia and is fatal unless medical help is available immediately.

Causes and symptoms
In many cases, the cause of an arrhythmia is unknown. Some known causes of arrhythmias include heart disease, stress, caffeine, tobacco, alcohol, diet pills and decongestants in cough and cold medicines.

Symptoms of an arrhythmia include a fast heartbeat, pounding or fluttering chest sensations, skipping a heartbeat, "flip-flops," dizziness, faintness, shortness of breath, and chest pains.

Detection
It is diagnosed by examination with a stethoscope, electrocardiograms and electrophysiologic studies.

Sometimes, arrhythmias can be identified by listening to the patient's heart through a stethoscope. But as arrhythmias are not always present, they may not occur during the physical examination.

Treatment
Many arrhythmias do not require any treatment. For serious arrhythmias, treating the underlying heart disease sometimes controls the arrhythmia.

In some cases, the arrhythmia itself is treated with drugs, electrical shock (cardioversion), implanting automatic implantable defibrillators, pacemakers, catheter ablation, or surgery.

Supraventricular Arrhythmias are often treated with drug therapy while Ventricular Arrhythmias require more complex treatment.

1. Drug therapy can manage many arrhythmias, but finding the right drug and dosage requires care and takes time.

Common drugs for suppressing arrhythmias include beta-blockers, calcium channel blockers, quinidine, digitalis preparations, and procainamide. Because of their potential serious side effects, stronger drugs are used only to treat life-threatening arrhythmias. All the drugs used to treat arrhythmias have possible side effects, ranging from mild complications with beta-blockers and calcium channel blockers to more serious effects of stronger drugs that can cause or make arrhythmias worse. Response to drugs is usually measured by ECG, Holter monitor or electrophysiologic study.

2. Pacemakers that send electrical signals to make the heart beat properly can be implanted under the skin during a simple procedure. Pacemakers are used to correct bradycardia and are sometimes used after surgical or catheter ablation.

3. Automatic implantable defibrillators correct life-threatening ventricular arrhythmias by recognising them and then restoring a normal heart rhythm by pacing the heart or giving it an electric shock. They are implanted within the chest wall without major surgery and store information for future evaluation by physicians.

Automatic implantable defibrillators have proven to be more effective in saving lives than drugs alone.

They are often used in conjunction with drug therapy.

4. Ablation, a procedure to alter or remove the heart tissue causing the arrhythmia in order to prevent a recurrence, can be performed through a catheter or surgery. Supraventricular tachycardia can be treated successfully with ablation. Ablation treatments are used when medications fail.

5. Maze surgery treats atrial fibrillation by making multiple incisions through the atrium to allow electrical impulses to move effectively. This is often recommended for patients who have not responded to drugs or cardioversion.

Heart failure is a condition in which the heart loses the ability to pump enough blood to the body's tissues. As a result, the main body organs and other tissues do not receive enough oxygen and nutrients to function properly.

A person with heart failure suffers a build-up of fluid in the tissues, called oedema. Heart failure as a result of fluid build-up is called congestive heart failure. Where oedema occurs in the body depends on the part of the heart that is affected by heart failure. For most people, heart failure is a chronic disease with no cure.

However, it can be managed and treated with medicines and changes in diet, exercise and lifestyle habits. Heart transplantation is considered in some cases.

Causes and symptoms
The most common causes of heart failure are:
• coronary heart disease and heart attack (which may be "silent")
• cardiomyopathy (disease of the heart muscles)
• high blood pressure (hypertension)
• heart valve disease
• congenital heart disease
• alcoholism and drug abuse

In coronary heart disease, the arteries supplying blood to the heart become narrowed or blocked. A person has a heart attack when blood flow to an area of the heart is completely blocked. The heart muscle suffers damage when its blood supply is reduced or blocked. If the damage affects the heart's ability to pump blood, heart failure develops. Some heart attacks go unrecognised.

Cardiomyopathy may be caused by coronary artery disease and various other heart problems. Sometimes, the cause cannot be found, in which case it is called idiopathic cardiomyopathy. Cardiomyopathy can weaken the heart muscle, leading to heart failure.

High blood pressure is another common cause of heart failure. High blood pressure makes the heart work harder to pump blood. After a while, the heart cannot keep up and the symptoms of heart failure develop.

Defects of the heart valves, congenital heart diseases, alcoholism, and drug abuse cause damage to the heart that can all lead to heart failure.

A person with heart failure may experience the following:
• shortness of breath
• frequent coughing, especially when lying down
• swollen feet, ankles, and legs
• abdominal swelling and pain
• fatigue
• dizziness or fainting
• sudden death

A person with heart failure may have shortness of breath and coughing caused by the fluid build-up in the lungs. Pulmonary oedema may cause the person to cough up bubbly phlegm that contains blood. Other symptoms of heart failure include fluid build-up in the veins and body tissues causing swelling of the feet, legs and abdomen. When body tissues, such as organs and muscles, do not receive enough oxygen and nutrients, they cannot function well, leading to tiredness and dizziness.

Detection
Diagnosis of heart failure is based on:
• symptoms
• medical history
• physical examination
• chest radiograph
• electrocardiogram (ECG; also called EKG)
• other imaging tests
• cardiac catheterisation

Symptoms can provide important clues to the presence of heart failure.

Shortness of breath while engaging in activities and episodes of shortness of breath during sleep are classic symptoms of heart failure.

During the physical examination, the physician listens to the heart and lungs with a stethoscope for tell-tale signs of heart failure such as irregular heart sounds, "gallops," a rapid heart rate, and murmurs of the heart valves. If there is fluid in the lungs, crackling sounds may be heard. Rapid breathing or other changes in breathing may also be present. Patients with heart failure may also have a rapid pulse.

By pressing on the abdomen, the physician can feel if the liver is enlarged. The skin of the fingers and toes may have a bluish tint and feel cool if not enough oxygen is reaching them.

Chest radiographs can show if there is fluid in the lungs or if the heart is enlarged. Abnormalities of heart valves and other structures also may be seen on chest radiograph.

An electrocardiogram gives information on the heart rhythm and the size of the heart and shows if the heart chamber is enlarged or if there is damage to the heart muscle from blocked arteries.

Echocardiography can show if the heart wall or chambers are enlarged and if there are abnormalities of the heart valves. An echocardiogram can be used to find out how much blood the heart is pumping.

Radionuclide ventriculography also measures the ejection fraction by imaging with very low doses of an injected radioactive substance as it travels through the heart.

Cardiac catheterisation is used to measure pressure in the heart and the amount of blood pumped by the heart. This test can help find abnormalities of the coronary arteries, heart valves, heart muscle, and other blood vessels. Combined with echocardiography and other tests, cardiac catheterisation can help find the cause of heart failure. However, this is not always necessary.

Treatment
Heart failure is usually treated with lifestyle changes and medicines. Dietary changes to maintain proper weight and reduction of salt intake may be needed. Reducing salt intake helps to lessen swelling in the legs, feet and abdomen. Appropriate exercise such as alking, cycling, swimming, or low-impact aerobic exercises may be recommended, but it is important that heart failure patients begin an exercise programme with the advice of their doctors. The

National Heart Centre Singapore and Changi General Hospital offer good Cardiovascular Rehabilitation and Preventive Cardiology Programmes for patients identified to have multiple risk factors for heart disease or who have just undergone open-heart surgery.

Other lifestyle changes that may reduce the symptoms of heart failure include stopping smoking or other tobacco use, eliminating or reducing alcohol consumption and not using harmful drugs.

One or more of the following types of medicines may be prescribed for heart failure:
• diuretics
• diagoxin
• vasodilators
• beta blockers
• angiotensin converting enzyme inhibitors (ACE inhibitors)
• angiotensin receptor blockers (ARBs)
• calcium channel blockers

Diuretics eliminate excess salt and water through the kidneys by making patients urinate more often. This helps reduce the swelling caused by fluid build-up in the tissues. Digoxin helps the heart muscles have a stronger pumping action. Vasodilators, ACE inhibitors, ARBs and calcium channel blockers lower blood pressure and expand the blood vessels making it easier for the heart to pump blood through the vessels.

Sometimes, surgery is needed to correct abnormalities of the heart or heart valves that cause heart failure.

Congenital heart defects and abnormal heart valves can be repaired with surgery. Blocked coronary arteries can usually be treated with angioplasty or coronary artery bypass surgery.

With severe heart failure, the heart muscle may become so damaged that available treatments do not help. Patients with end-stage heart failure are usually considered for heart transplantation when all other treatments do not work.