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Clinical Specialties - Cardiac

Heart Anatomy & Physiology

The heart is a highly sophisticated and specialised muscle that carries oxygen and other nutrients to every organ and living cell in the body. Sometimes, however, it does not work as well as it should causing pain, discomfort, shortness of breath or a myriad of other symptoms that need to be reviewed by a specialist. Your general practitioner (GP) will assess your condition and then advise you of the most appropriate course of action.

There are many specialists involved in the care of your heart, lungs and surrounding vessels and arteries. A cardiologists' focus is to diagnose and treat heart disease, including genetic or congenital (present at birth) disorders, while an interventional cardiologist has further specialised and is capable of treating heart disease using interventional procedures such as angioplasty or stents which are performed in cardiac catheterisation labs.

If your condition requires open surgery to the heart or lungs and cannot be fixed through a minimally invasive technique then the procedure is referred to as surgical. The San has highly skilled cardiothoracic surgeons who perform a range of surgical procedures.

Sydney Adventist Hospital has a remarkable team of cardiac specialists known for some of the best patient outcomes of any private hospital in NSW. It also offers state-of-the-art operating facilities and a remarkable level of care, making it a preferred choice for patients undergoing heart procedures and surgery.


The Anatomy and Physiology of the Heart

Anatomy of the HeartHow the Heart Functions

The heart is a specialised hollow organ that pumps blood around your body. It is about the size of your fist and is situated in the middle of your chest behind your breastbone. The blood that is pumped from the heart carries oxygen and other nutrients to every organ and living cell in the body.

Since the heart is a muscle it also needs its own regular supply of blood. This supply comes from arteries called coronary arteries. There are three main arteries and a network of vessels covering the surface of the heart.

The heart is composed of four chambers. There are two small chambers called atria (atrium is singular) at the top and two larger chambers called ventricles at the bottom. The atria collects blood that comes into the heart and then contracts to pump blood into the ventricles. The ventricles contract to pump blood out of the heart. This pumping creates your heartbeat. The heart normally beats at between 50 and 100 beats per minute (bpm).

The heart also has four valves, each of which opens and closes from the pressure of the blood inside the chambers. A normal valve opens and closes tightly preventing backflow of blood. The normal pathway of bloodflow enters the right atrium and passes through the tricuspid valve into the right ventricle. The right ventricle then pumps the blood through the pulmonary valve to the lungs, where the blood gets its oxygen. The blood returns to the heart via the left atrium and passes through the mitral valve into the left ventricle. The blood is then pumped through the aortic valve into the aorta, which takes the blood rich in oxygen to the rest of the body.


Electrical Function

The heart has its own electrical system which allows it to beat irrespective of what the brain is doing. Its own natural pacemaker is located in the upper right atrium consisting of a small bundle of specialised cells known as the sinoatrial node (S-A node). Beginning at the S-A node, a wave of electrical impulses spreads through the atria causing them to contract and squeeze blood through the valves into the ventricles. The electrical impulses continues to travel to the atrioventricular node (A-V node), a second bundle of cells located at the junction between the atria and ventricles. Once the impulses reaches the A-V node the ventricles contract.

An adult’s heart rate may rise over 100 bpm during exertion or emotional stress. The S-A node automatically increases your heart rate in response to your body’s needs when a faster bloodflow is required. For example, during exercise the heart rate will increase as the muscles in the arms and legs require a greater blood supply.


Main Types of Heart Problems

Coronary Artery Disease

In a normal healthy heart, the coronary arteries are flexible blood vessels free of fatty deposits (called "plaques"). A ‘healthy’ heart muscle receives all the blood it requires even when it is working harder than usual. Coronary artery disease is said to be present when plaque builds up on the inner wall of an artery, restricting or blocking blood flow. This is called "atherosclerosis", and symptoms may develop at varying stages of the disease process.

Angina Pectoris (commonly known as Angina)

When the artery is partially blocked and your heart needs increased oxygen, such as during exercise, stress or after a heavy meal, the heart muscle may receive insufficient oxygen and angina can occur. Angina is the term used to describe the pain or discomfort in the chest that you may experience. As the disease in the artery progresses, angina can occur at rest or during sleep. The rate of progression of heart disease varies from person to person, as does the way it is experienced.

Angina may be experienced as:

  • A tightness, cramping or gripping feeling
  • A burning sensation
  • Pressure
  • Similar to indigestion
  • A choking feeling
  • Shortness of breath
  • A sharp pain
  • A dull ache


It is commonly felt in the chest but may begin or spread to the shoulders, neck and jaw or down the arms. You may also feel weak or sweaty. Sometimes angina is relieved by slowing down or stopping what you are doing. Sufferers of angina will have prescribed medication to take to deal with these symptoms. If after resting and taking the prescribed medication symptoms continue for longer than 15 minutes, then you should call an ambulance in case you are having a heart attack.

Myocardial Infarction (commonly known as a Heart Attack)

A myocardial infarction occurs when blood flow through the coronary artery is completely occluded. The part of the heart that the artery supplies becomes deprived of oxygen and is therefore damaged. This may affect the functioning of the heart depending on the size of the heart attack. If angina symptoms remain for longer than 15 minutes, despite using prescribed medication and resting, medical attention should be sought as you may be having a heart attack.

The signs may be similar to angina and you may experience:

  • A tightness, cramping or gripping feeling
  • A burning feeling
  • Pressure on the chest area
  • Similar to indigestion
  • A choking feeling
  • Shortness of breath
  • A sharp pain
  • A dull ache


You may feel this in the centre of the chest, the left side of the chest, the upper back, into your neck or jaw or down the arms. Other symptoms include:

  • Sweating
  • Feeling weak or faint
  • Nausea or vomiting


Remember if the pain or discomfort persists for longer than 15 minutes and you have tried your nitroglycerine medication, call an ambulance. Do not attempt to drive yourself to hospital. Time is essential so if in doubt have it checked out; it is always better to err on the side of caution.

Congestive Heart Failure

This is also known as Congestive Cardiac Failure (CCF) and means your heart is not pumping as effectively as it should to meet the demands of the body. This weakness may be caused by damage to the heart from previous heart attacks, disease of the arteries in the heart, disease of the heart valves, disease of the heart muscle or long-term high blood pressure.

Your doctor will tell you if you have this condition and these are some of the common symptoms:

  • Excessive tiredness or weakness
  • Shortness of breath, wheezing or coughing with mild exertion
  • Difficulty breathing when lying down
  • Swollen ankles and/or feet
  • Dizzy spells


These symptoms may possibly be related to another condition, but if you have been told you have congestive heart failure there are ways to help your heart to function as best as it can. Various medications can be prescribed that may help reduce the amount of fluid in your body or may help the heart to pump more efficiently. Below are some things you could do to help with this condition.

  • Take the prescribed medications precisely as directed and do not allow yourself to run out.
  • Check with your doctor whether you need to limit your fluid intake.
  • Reduce your salt intake to help reduce fluid retention.
  • Ensure that you get enough rest and pace your activities.
  • Weigh yourself at the same time each day and keep a record as weight gain may indicate fluid retention.
  • Maintain close contact with your local doctor and report any changes in your condition such as increased shortness of breath, sudden weight gains, getting tired more easily, increased swelling in the feet or ankles, if you notice that you are passing urine less frequently, dizziness, or any chest pain or discomfort.
  • Ensure your blood pressure is taken regularly.
  • Alcohol intake should not exceed one standard drink per day for a woman and two standard drinks per day for a man; Excess alcohol may produce adverse effects on the heart.
  • Try to include some regular exercise daily that is appropriate for your condition.


Heart failure can also result from a condition called cardiomyopathy. There are different types of cardiomyopathy. It may be caused by infection, alcohol abuse and some drugs. It can be an inherited disease and sometimes the cause is not known. Your doctor will discuss this condition with you and how best to manage it. We can put you in contact with the Cardiomyopathy Association of Australia if you have been diagnosed with this condition.

Abnormal Heart Rhythms (Arrhythmias)

An arrhythmia is any variation from the normal rate or rhythm of the heartbeat. You may have been diagnosed with an arrhythmia while in hospital or have presented to your doctor and upon investigation of your symptoms an arrhythmia has been found. Arrhythmias may produce no symptoms or may include light-headedness, fainting, palpitations, chest pain and shortness of breath. Even in the absence of symptoms some arrhythmias may warrant treatment. However, more serious arrhythmias need to be treated. Medication may cure or control the arrhythmia but sometimes other interventions are required.

Arrhythmias occur because the heart rate is too slow (bradycardia- less than 50 beats/minute), too fast (tachycardia greater than 100 beats/minute) or irregular. Bradycardia may occur because electrical impulses arise very slowly from the cardiac pacemaker or because they fail to conduct through the specialised conduction system (heart block). Tachycardia may occur because electrical impulses generate too frequently or because of abnormal electrical pathways within the heart which essentially act as “short circuits”.

Some other common arrhythmias are:

  • Ectopic beats – when the heart beat fires too early from either the atria or ventricles (therefore you are receiving an early heartbeat.) This is very common in people with a healthy heart and requires no treatment.
  • Atrial fibrillation – an irregular heart rhythm originating from no set place in the atria.
  • Heart block – occurs when the electrical impulse becomes disturbed while travelling down the conduction pathway.
  • Ventricular tachycardia – a more serious tachycardia that originates in the ventricles.
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