Cardiac Imaging
Transthoracic Echocardiogram (TTE)
An echocardiogram or “echo” is a type of ultrasound. In terms of a transthoracic echo (TTE), the test is non-invasive and uses sound waves to produce a moving image of your heart. The cardiac sonographer will use a device known as a transducer to press against gel applied to the skin of your chest, and direct sound waves to your heart. These sound waves generate images of the tissues and spaces in your heart, and allows a doctor to see any abnormalities in the cardiac structure or blood flow.
Your doctors may refer you for an echocardiogram to gather information about how your heart is built, and how it is positioned within your chest.
By creating an ultrasound image, we can view the size and thickness of your heart chambers, valves, and the sac that holds your heart muscles and assess how well they function, as well as evaluate your risk of having blocked arteries, also known as coronary artery disease.
During an Echocardiogram, you will be asked by the cardiac sonographer to remove your top clothing and lie on the exam couch. The lights will be dimmed so that the cardiac sonographer can see the black and white images as clearly as possible. You may be asked to roll on your side or hold your breath, so the heart is at its most visible through the chest wall. The sonographer may press firmly with the transducer which can cause some discomfort, but it is tolerable and often only for a few seconds. The entire test should take no more than 30 minutes, and you are able to return to normal activities as soon as you have completed the procedure. There are also no known risks associated with an Echocardiogram, with no radiation used in the test, and no invasive measures used.
For the test you should wear comfortable clothing with tops that are easily removed. Smoking should be avoided for 4 hours before the test, and caffeine products such as coffee, cola, or tea for 2 hours before the test. There will be no down time after the procedure and you can return to normal activity immediately.
Transoesophageal Echocardiogram (TOE)
An echocardiogram or 'echo' is a type of ultrasound. Ultrasound waves are used to create a moving image of your heart, which allows your doctor to assess the tissues and spaces in your heart. There are cases in which a transthoracic echocardiogram cannot obtain a sufficient image of difficult to access areas of your heart, due to the ribs and lungs interfering with the sound waves. In these situations, or when there are concerns of infections, growths, or tumours in hidden parts of the heart, a transoesophageal echo (TOE) is required.
At Heart of Melbourne, we maintain great networks within private and public hospitals which allows your doctor greater flexibility when arranging a TOE for you. Our staff will organise for you to attend one of these hospitals, and under a sedation or general anaesthetic, a thin scope will be inserted through your mouth, into the throat and oesophagus. By producing the sound waves from this vantage point, the heart can be visualised very closely and in further detail than the standard TTE.
At the time of your TOE, an intravenous line will be inserted to allow for administration of sedation or anaesthetic. You will be given a numbing spray and gargle, and you will be asked to lie on your left side on the exam table. You will be given a plastic guard to protect your teeth and the scope during the procedure. The scope will pass into your mouth and throat, and swallowing may be required to ease the positioning in the oesophagus. Once the scope is in place, there should be no discomfort, and the process should take between 30 – 90 minutes.
Once the procedure is complete, you will be required to wait until the sedation and numbness has worn off, and invited to drink some cool fluids. As long as there are no issues with this, the nursing staff will offer you something to eat, and encourage you towards discharge. Your accompanying person is then able to transport you home.
CT Coronary Angiogram (CTCA)
CT Coronary Angiography (CTCA) is a non-invasive way of checking your heart and its arteries.
A conventional or “invasive” Coronary Angiography remains the gold standard for diagnosing coronary artery disease (narrowing or blockages in the arteries of your heart). However, CTCA avoids the risks associated with invasive procedures for patients with intermediate risk for CAD, and is performed using the ultrafast CT scanners. While it is a very good alternative, you cardiologist will decide if it is suitable for you or not.
The test involves radiations and contrast. Your cardiologist will ensure if your kidneys are able to handle the contrast dose required for this scan.
The preparation for this procedure is fairly similar to other CT scans with some additions. You will be asked to change into a gown. Your blood pressure and heart rate will be monitored. An ideal heart rate for this scan is around 60 beats per minute. Your cardiologist will give you a prescription for the heart slowing medications if your heart rate is high. You may require additional medication on the day of scan.
You will have a cannula inserted in your arm to give you the contrast injection for the test. It may give you a warm feeling which is normal.
While the procedure itself takes approximately 5-10 minutes, allow up to 2 hours for the whole process of preparation etc.
Medications:
Your cardiologist will usually prescribe you the following regimen (or something similar):
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If heart rate less than 65, no medication required
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If heart rate between 65 and 75, Metoprolol 50 mg half an hour prior to the appointment
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If heart rate more than 75, Metoprolol 50 mg previous night and 50 mg half an hour prior to the appointment
Avoid caffeine, coffee, tea, or energy drinks for 24 hours prior to the test. You will be required to fast for 3 hours before the test however you are allowed to drink water during these 3 hours.
CT Calcium Score
CT Calcium score is a specialised type of CT scan for your heart that provides information on the calcium-containing plaque in the arteries. By measuring the amount of calcium in your heart arteries, your cardiologist would be able to inform you of your risk of having coronary heart disease before having any signs and symptoms.
With age, plaque can build up inside your heart arteries. This is often called hardening of the arteries. The amount of calcium in the arteries varies with age. The older you are the more likely you are to have some degree of calcium in the arteries.
This is a screening test, i.e. it will tell you the risk of having disease whether it is low, intermediate, or high. It does not help diagnose or rule out narrowing or blockages in the arteries, and is therefore not recommended for people who have symptoms or are considered high risk for developing heart disease.
The test involves radiation however the dose is fairly low. This CT scan does not require contrast injection. The actual CT scan is very quick but it may require you to hold your breath between 5 to 10 seconds.
A general guide to Calcium score (also known as Agatston):
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Score 0: Low risk of heart disease or future heart attacks
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Score 1-10: Mild Risk
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Score 11-100: Moderate Risk
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Score 101-400: High Risk
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Score greater than 400: Severe disease
