Heart & Types of heart disease

1399/07/01 - 15:43 / 208

Structure of the Heart


The human heart is a four-chambered muscular organ shaped and sized roughly like a man's closed fist with two-thirds of the mass to the left of midline.

The heart is enclosed in a pericardial sac that is lined with the parietal layers of a serous membrane. The visceral layer of the serous membrane forms the epicardium 

Layers of the Heart Wall

Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.


Chambers of the Heart

The internal cavity of the heart is divided into four chambers:

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle

The two atria are thin-walled chambers that receive blood from the veins. The two ventricles are thick-walled chambers that forcefully pump blood out of the heart. Differences in thickness of the heart chamber walls are due to variations in the amount of myocardium present, which reflects the amount of force each chamber is required to generate.

The right atrium receives deoxygenated blood from systemic veins; the left atrium receives oxygenated blood from the pulmonary veins








Valves of the Heart

Pumps need a set of valves to keep the fluid flowing in one direction and the heart is no exception. The heart has two types of valves that keep the blood flowing in the correct direction. The valves between the atria and ventricles are called atrioventricular valves (also called cuspid valves), while those at the bases of the large vessels leaving the ventricles are called semilunar valves.

The right atrioventricular valve is the tricuspid valve. The left atrioventricular valve is the bicuspid, or mitral, valve. The valve between the right ventricle and pulmonary trunk is the pulmonary semilunar valve. The valve between the left ventricle and the aorta is the aortic semilunar valve.

When the ventricles contract, atrioventricular valves close to prevent blood from flowing back into the atria. When the ventricles relax, semilunar valves close to prevent blood from flowing back into the ventricles.


Pathway of Blood through the Heart


While it is convenient to describe the flow of blood through the right side of the heart and then through the left side, it is important to realize that both atria and ventricles contract at the same time. The heart works as two pumps, one on the right and one on the left, working simultaneously. Blood flows from the right atrium to the right ventricle, and then is pumped to the lungs to receive oxygen. From the lungs, the blood flows to the left atrium, then to the left ventricle. From there it is pumped to the systemic circulation.

Blood Supply to the Myocardium

The myocardium of the heart wall is a working muscle that needs a continuous supply of oxygen and nutrients to function efficiently. For this reason, cardiac muscle has an extensive network of blood vessels to bring oxygen to the contracting cells and to remove waste products.

The right and left coronary arteries, branches of the ascending aorta, supply blood to the walls of the myocardium. After blood passes through the capillaries in the myocardium, it enters a system of cardiac (coronary) veins. Most of the cardiac veins drain into the coronary sinus, which opens into the right atrium.


What is heart disease?

Heart disease is any condition that affects the structure or function of the heart. Most people think of heart disease as one condition. But in fact, heart disease is a group of conditions with many different root causes.












Types of heart disease

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There are many different types of heart disease. Some types can be grouped together according to how they affect the structure or function of your heart.  

1. Heart rhythm disorders (arrhythmias) cause the heart to beat too slowly, too quickly or in a disorganised fashion. There are many types of arrhythmias – some have no symptoms or warning signs; others can be sudden and fatal.

2. Coronary artery and vascular disease are due to hardening of the arteries (atherosclerosis). It happens when the arteries in your heart are narrowed or blocked. It’s the most common kind of heart disease and causes most heart attacks as well as Angina (chest pain). Vascular disease is problems in other blood vessels which reduce blood flow and affect the function of your heart.


If your coronary arteries become partially blocked, it can cause chest pain (angina). This can be a mild, uncomfortable feeling similar to indigestion.

However, a severe angina attack can cause a painful feeling of heaviness or tightness, usually in the centre of the chest, which may spread to the arms, neck, jaw, back or stomach.

Angina is often triggered by physical activity or stressful situations. Symptoms usually pass in less than 10 minutes, and can be relieved by resting or using a nitrate tablet or spray.

3. Structural heart disease refers to abnormalities of the heart’s structure – including its valves, walls, muscles or blood vessels near the heart. It can be present at birth or acquired after birth through infection, wear and tear, or other factors. People living with heart defects and their families need support throughout every age and stage of their life, often requiring ongoing medical care and surgical procedures.




4. Heart failure

Heart failure  is a serious condition that develops after the heart becomes damaged or weakened. The two most common causes of heart failure are Heart attacks and

 high blood pressure. There is no cure, but early diagnosis, lifestyle changes and medication can help people lead an active life, stay out of hospital and live longer.

Other heart diseases include infections, enlarged heart muscle and inherited disorders.

 Heart failure can also happen in people with CHD. The heart becomes too weak to pump blood around the body, which can cause fluid to build up in the lungs, making it increasingly difficult to breathe.

Heart failure can happen suddenly (acute heart failure) or gradually, over time (chronic heart failure).

Heart attacks

If your arteries become completely blocked, it can cause a heart attack (myocardial infarction).

Heart attacks can permanently damage the heart muscle and, if not treated straight away, can be fatal.

Dial 115 for immediate medical assistance if you think you're having a heart attack.

Although symptoms can vary, the discomfort or pain of a heart attack is usually similar to that of angina. However, it's often more severe and may happen when you're resting.









During a heart attack, you may also have the following symptoms:

•         pain in other parts of the body – it can feel as if the pain is travelling from your chest to your arms, jaw, neck, back or stomach

•         lightheadedness

•         sweating

•         nausea

•         breathlessness

The symptoms of a heart attack can also be similar to indigestion. For example, they may include a feeling of heaviness in your chest, a stomach ache or heartburn.

A heart attack can happen at any time, including while you're resting. If heart pains last longer than 15 minutes, it may be the start of a heart attack.

Unlike angina, the symptoms of a heart attack are not usually relieved using a nitrate tablet or spray.

A heart attack can sometimes happen without any symptoms. This is known as a silent myocardial infarction and is more common in older people and people with diabetes.



When someone has a heart attack, a bystander – often a relative with no medical expertise – is usually the first on the scene. However, less than 1% of the population have attended an emergency life support course. The build-up of atheroma makes the arteries narrower, restricting the flow of blood to the heart muscle. This process is called atherosclerosis

Causes of Atherosclerosis

Your risk of developing atherosclerosis is significantly increased if you:

· smoke

· have high blood pressure (hypertension) 

· have high cholestrol

· have high levels of lipoprotein (a)

· do not exrcise regulary

· have diabetes











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Other risk factors for developing atherosclerosis include:

· being obese or overweight

· having a family history of CHD – the risk is increased if you have a male relative under the age of 55, or a female relative under 65, with CHD

· Smoking

· Smoking is a major risk factor for coronary heart disease. Both nicotine and carbon monoxide (from the smoke) put a strain on the heart by making it work faster. They also increase your risk of Blood clots.

· Other chemicals in cigarette smoke can damage the lining of your coronary arteries, leading to furring of the arteries. Smoking significantly increases your risk of developing heart disease.

· Read about how to stop smoking and stop smoking treatments.

· High blood pressure

· High blood pressure (hypertension) puts a strain on your heart and can lead to CHD.

· Read more about high blood pressure. 

· High cholesterol

· Cholesterol is a fat made by the liver from the saturated fat in your diet. It's essential for healthy cells, but too much in the blood can lead to CHD.

· Read more about high cholesterol. 

· High lipoprotein (a)

· Like cholesterol, lipoprotein (a), also known as LP(a), is a type of fat made by the liver. It's a known risk factor for cardiovascular disease and atherosclerosis.

· The level of LP(a) in your blood is inherited from your parents. It's not routinely measured, but screening is recommended for people with a moderate or high risk of developing cardiovascular disease.

· Heart UK has more information about high lipoprotein. 

· Lack of regular exercise

· If you're inactive, fatty deposits can build up in your arteries.

· If the arteries that supply blood to your heart become blocked, it can lead to a heart attack. If the arteries that supply blood to your brain are affected it can cause a stroke.

· Read about the physical activity guidelines for adults aged19 to 64. 

· Diabetes

· A high blood sugar level may lead to diabetes, which can more than double your risk of developing CHD.

· Diabetes can lead to CHD because it may cause the lining of blood vessels to become thicker, which can restrict blood flow.



Heart disease can be caused by:

· Medical conditions

· High blood pressure

· High cholesterol levels

· Diabetes

· high blood pressure during pregnancy pre-eclampsia

· sleep apnea

· Lifestyle risk factors

· Unhealthy diet

o not enough physical activity

o unhealthy weight 

o  smoking (tobacco misuse)

o too much alcohol 

o stress

o recreational drug use

o birth control or hormonr replacement therapy

· Risk factors you cannot control

· sex– a woman’s risk of heart disease and stroke changes over her lifetime

o age – the older you are, the higher your risk of heart disease

o family and medical history

o South Asian and African heritage

o Indigenous heritage 

o personal circumstances – including access to healthy food, safe drinking water, health services and social services


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A number of different tests are used to diagnose heart-related problems, including:

•         exercise stress tests

•         electrocardiogram (ECG)

•         X-rays

•         echocardiogram

•         blood tests

•         coronary angiography

•         radionuclide tests

•         MRI scans

•         CT scans

•         Treatment-Coronary heart disease



Heart disease is preventable. And if you’ve been diagnosed with a heart condition, there are ways you can reduce your risk of developing more heart problems. Consider these heart-healthy steps:

· Be smoke-free.

· Be physically active.

· Know and control your blood pressure.

· Eat a healthy diet that is lower in fat, especially saturated and trans fat.

· Achieve and maintain a healthy weight.

· Manage your diabetes.

· Limit alcohol use.

· Reduce stress.

· Visit your doctor regularly and follow their advice.

For more information about how to live a healthier lifestyle, look in the get healthy section of this website.


To diagnose heart disease, your healthcare provider will review your medical and family history, and give you a complete physical exam. They may also run tests. The type of tests depends on the signs and symptoms you are experiencing.


Treatment for heart disease includes medication, lifestyle changes (healthy eating, stay active, reduce stress) and surgery or other procedures. Treatment depends on the type and severity of your heart disease. You and your doctor will discuss the treatment options and decide which is best for you and your circumstances.





cardiac rehabilitation is a personalised program of exercise, education and counselling to help you recover from heart disease. Rehab will help you regain your strength and reduce your risk of having other heart problems in the future. Talk to your doctor about how to find a program in your area or contact your public health department or hospital. 
It’s normal to feel worried or afraid after a diagnosis of heart disease. Find someone you can turn to for emotional support like a family member, friend, doctor, mental health worker or support group

The recovery and support section is full of practical advice and tips to support you on your recovery journey. 

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Neshat Khosravi - Microbiologist






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