Cardiac CT including CT FFR and procedural planning studies
Cardiac Computed Tomography (Cardiac CT) is a new technology which uses x-rays to create very accurate pictures of the heart and heart arteries. We are increasingly using this test in place of coronary angiography. Wythenshawe Hospital is one of the few hospitals in the North West that is able to provide Cardiac CT and we have a dedicated Cardiac CT scanner in the North West Heart Centre. The most common reason that a Cardiac CT is performed is for the investigation of chest pain, although you will also have a Cardiac CT scan if your doctor is planning a transcatheter aortic valve implantation (TAVI) procedure and sometimes a Cardiac CT is used instead of a coronary angiogram in patients referred for valve replacement surgery and is also often used for creating accurate pictures of the main blood vessel leaving the heart (aorta).
The most common type of Cardiac CT is a CT coronary angiogram (CTCA). This is a scan where the focus is on visualising the coronary arteries to evaluate for narrowed or blocked arteries. The CT scanner creates very accurate pictures of the heart arteries.
CT fractional flow reserve (CTFFR) is a state-of-the-art technology that can be performed to evaluate whether the narrowings or blockages seen on the CT coronary angiogram are causing a problem or not. As you age, everyone develops small cholesterol plaques in their heart arteries. Some people have more plaques than others and often risk factors for heart disease mean that these plaques accumulate faster (e.g. male sex, diabetes, high blood pressure, high cholesterol etc). If these plaques build up significantly then they can cause narrowed or blocked arteries. Sometimes narrowed arteries are ‘silent’ i.e. they are not causing any problems to the heart and despite their presence the blood flow to the heart is not affected. Sometimes these blockages / narrowings are causing a problem with blood supply to the heart (usually causing chest pain or shortness of breath). When we perform a cardiac CT coronary angiogram we can see these blockages or narrowings clearly, but it is difficult to tell whether these are ‘silent’ (harmless) or causing a problem with blood supply. CT FFR can be helpful in this circumstance. CT FFR is a computer technology which uses special advanced software to tell between silent and harmful heart artery narrowings. There are only a few centres across the UK that are able to offer this service and we are pleased that Wythenshawe is one of these centres. Once your CT scan has been read by one of our experienced Doctors, if they see a narrowing it may be sent off for CT FFR analysis. The benefit of this technology is it often prevents the need for you to undergo a second test.
A CT Aortogram is a test where the CT scanner takes detailed pictures of the main blood vessel leaving the heart (aorta). We often use this test to monitor the size of the aorta prior to heart surgery or if you have been diagnosed with an aortic condition / aneurysm / stretch.
A TAVI CT is a Cardiac CT looking carefully at the heart, main blood vessel leaving the heart (aorta), coronary arteries and the arteries around the body. It allows your medical team to assess your suitability for a TAVI procedure.
You will be invited to attend the North West Heart Centre at Wythenshawe Hospital on the day of your Cardiac CT. You will be asked to complete a patient questionnaire and change into a gown. A cannula (drip) will be inserted into your arm and you will lay on your back on the CT scanner table. Some stickers will be placed on your chest to monitor your heartbeat and a cuff placed on your arm to monitor your blood pressure. For most types of scan you will be given some medication called a beta-blocker via the drip (cannula) in your arm. You may also be given a spray of a medication called GTN (the red angina spray) under your tongue. You will be asked to raise your hands above your head. The doctor or radiographer will then leave the room and ask you via the intercom to hold your breath for 10-20 seconds. The x-ray contrast (dye) will be automatically administered into the drip (cannula) in your arm and pictures of the heart will be taken. You may hear the CT scanner make a noise as the images are being taken. Sometimes the x-ray contrast (dye) makes you feel flushed and as if you have a full bladder – this is not harmful and only lasts a few minutes.
It takes less than a minute to take all the required pictures of your heart for a Cardiac CT but you should expect the procedure to take around an hour. You will be asked to stay in the department for a period of time after the scan to ensure that you feel well afterwards.
You will not receive the results of your scan on the day as the images have to be reviewed by a doctor. Your scan results will be sent to the Healthcare Professional who requested the test (usually your Cardiologist or Chest Pain Nurse).