A heart attack can occur when the blood flow through one or more of the coronary arteries to the heart is reduced
What does the cardiovascular system do?
The cardiovascular system (CVS) consists of the heart, lungs and blood vessels. It is responsible for transportation of vital nutrients, gases and hormones throughout the body. The heart functions as the central pump with the blood vessels the pipes of the body. The CVS is controlled by a number of internal and external systems, which keep the CVS in balance with the needs of the body.
The heart is a pear shaped organ positioned centrally within the chest cavity with the apex extending over to the left nipple. The heart is a divided into a right and left side, each side has an atrium and ventricle. Heart valves and the contraction of the heart muscle control blood flow through the heart. The right side receives de-oxygenated blood from the major veins of the body and pumps this blood into the lungs. The left side of the heart then receives oxygen rich blood from the lungs and pumps this blood into the Aorta and arteries of the body. This pumping action is a complex well-coordinated activity that cannot be fully explained here. The heart receives its blood supply via the left and right coronary arteries.
Poor or abnormal function of the cardiovascular system
May be a result of:
- Insufficient blood supply due to dehydration, bleeding or swelling;
- A poor blood supply to the heart, where there is not enough oxygen and other nutrients for its work;
- Poor lung function or obstruction to blood flow in the lungs, which places a strain on the heart muscle;
- Too many or too few electrolytes (eg. potassium, magnesium) that cause irregular heartbeats or dangerous rhythms in the heart.
- Weakness of blood vessel walls.
- Heart muscle weakness
This image was sourced using a google image search
What is an acute myocardial infarction?
An acute myocardial infarction is also known as a heart attack. A heart attack can occur when the blood flow through one or more of the coronary arteries to the heart is reduced, therefore reducing the vital continuous oxygen supply. Factors that may contribute to a heart attack include: ageing, a clot (thromboembolism) completely or partially obstructing a vessel, diabetes mellitus, high levels of cholesterol, high blood pressure (hypertension), a diet high in fat or salt, smoking, obesity, or a previous history or family history of cardiovascular disease. A heart attack results in an area of the heart being permanently damaged.
Signs and Symptoms
- The key sign of an impending heart attack is chest pain. This pain can be described as extreme pressure in the chest, a heaviness or tightness. It is commonly in the center fo the chest but can also be felt in the throat or going the left or both arms.
- Some patients do not get any pain but may feel extremely tired.
- Other symptoms include profuse sweating, nausea or vomiting, anxiety, shortness of breath dizziness and cough.
A heart attack is a medical emergency and it is vital the patient gets to an emergency room as soon as possible. It is probably a bad idea for them to drive themselves, so ringing an ambulance is important.
Diagnosis and treatment:
Heart attacks can be diagnosed using 12 lead ECGs (electrocardiography), blood tests, and a history from the patients. Echocardiography (ultrasound of the heart may also be used). Treatment is focused on saving as much heart muscle as possible and will be started in the emergency room. The patient will be connected to a heart monitor and an oxygen mask will be applied. An IV cannualae will also be inserted. An ECG and a chest x-ray will be done and bloods drawn. An emergency or a cardiac doctor will authorize the commencement of active treatment which would include: anginine tablet to improve blood flow to the heart and morphine for the pain. The next step depends on the hospital the patient is at. Under most circumstances the patient will receive a medication called a thrombolytic. This group of drugs dissolves the clot and restores blood flow and oxygen supply to the non-damaged areas of the heart as soon as possible. Following this the patient will be transferred to a coronary care or intensive care unit. Here, the patient will have blood taken regularly to monitor the levels of enzymes released by the heart when it is damaged. The patient will also have regular 12 lead ECGs performed to detect heart changes early. In some major centers a patient may be transferred from the emergency departement to the hospital's cardiac catheterization department. Here the cardiologist will perform coronary angiography to identify the blockages in the heart's arteries and open them up directly using drugs or balloon angioplasty.
Tests that may be done in the Coronary Care Unit
The patient in intensive/coronary care will be monitored very closely using a cardiac monitor. If the patient develops complications from the heart attack, they may require additional monitoring such as an arterial line or pulmonary artery catheter. On occasion full breathing support with a breathing tube (endotracheal tube) and breathing machine (ventilator) may also be required.
Some of the complications that can develop following a heart attack may include:
How long will the patient remain in Coronary Care?
Under most instances a patient who has had an AMI will be admitted to a coronary care unit. Outside the metropolitan areas the coronary care unit and the intensive care unit are combined. Where there is a separate coronary care unit the the patient will remain there for a short period. Ongoing treatment will depend on any ongoing symptoms and treatment options available. In rural and regional facilities, the patient will remain in the intensive/coronary care unit until the patient is stabilised for transfer to a hospital with cardiac interventions services such as angiography, cardiac stenting or cardiac surgery (cardiothoracic) .
A patient who has had an AMI will be admitted to a general intensive care unit when there condition has deteriorated to where they now require mechanical breathing (ventilator) or cardiovascular support (IABP).
The information contained on this page is general in nature and therefore cannot reflect individual patient variation. In addition it reflects Australian intensive care practice which may differ from other countries. It is meant as a back up to specific information which will be discussed with you by the Doctors and Nurses caring for your loved one. ICCMU attests to the accuracy of the information contained here BUT takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.
Acute Myocardial Infarction Version 1 (Author Meg Tuipulotu CNC GWAHS )
First Published October 2005