Following completion of this module you should be able to:
| Investigation | Explanation |
|---|---|
| Loop recorders (reveal monitor) | This is a small battery powered device which is implanted under the skin and records the heart rate and rhythm to identify if there are any problems. It is suited to patients who have described infrequent symptoms and can remain in place once the abnormal rhythm has been isolated. It is then removed after a period of time. |
| Myocardial perfusion scintigraphy: | Also known as a thallium scan, this shows how well the blood reaches the cardiac muscle through the coronary circulation. A small amount of thallium is injected into a vein and is then visualised by a moving camera outside of the body. Thallium does not travel well to areas of poor blood supply, therefore, the pictures demonstrate the amount of blood reaching cardiac muscle. |
| Coronary angiography (also called cardiac catheterisation): | This is a specialised x-ray of the heart which can be used to assess damage to the heart and for cardiac assessment. A catheter tube is inserted under local anesthetic into the main artery in the upper leg or lower arm and passed into the aorta. Dye is then injected which illuminates the coronary circulation. (This will be discussed in more detail in Modules 3 and 4), |
| Magnetic Resonance Imaging (MRI) : | This scan uses a magnetic field to produce detailed images of the heart and blood vessels. It is very helpful in gaining images from patients whose vessels and anatomy are difficult to see using angiography. |
| Electrophysiological studies: (EP studies) : | This allows the heart’s electrical activity to be analysed in great detail. This test has revolutionised the way we understand and treat fast or abnormal heart rhythms. Catheters are placed into a vein (usually in the groin). Then it is gently moved into position within the heart. There, the special electrode tip stimulates the heart and records the subsequent electrical activity. |
| Trans-oesphageal echocardiogram (TOE/TEE): | This is a specialised echo scan which involves passing a tube into the oesophagus and can examine the heart to give a different view from the back (posterior) of the heart rather than the front. It is used when cardiologists require specific information often in relation to the valves or any infective components. |
| CT scans of the heart: | Computerised tomography (CT) has been around since the 1970s. There are two ways in which a CT scan can be used to examine the heart – one is a CT coronary angiogram and the other is a CT calcium score.
A CT scan produces multiple images of the heart from different angles, which the cardiologist can then see on a computer screen. The images are picked up using detectors. The greater the number of detectors (the UK’s most commonly used version has 64) the clearer the image and the more useful it is in helping the cardiologist to make a diagnosis. |
| CT coronary angiogram: | A CT coronary angiogram is used to measure the blood flow through the coronary arteries. Similar to a conventional coronary angiogram, a CT coronary angiogram involves injecting an iodine-based dye into the bloodstream to highlight the blood vessels. However, unlike the traditional angiogram, which is a sophisticated x-ray of the arteries, the dye is injected into a small vein in the arm rather than an artery in the groin. The CT coronary angiogram is useful if the cardiologist thinks that it is unlikely that the patient has coronary heart disease but he or she cannot explain what is causing the patient’s symptoms. it is often used to rule out coronary heart disease, rather than to confirm it. It can also be useful if the patient has developed heart failure but the underlying cause of this is not clear. If coronary heart disease (CHD) is suspected, a traditional coronary angiogram is done. Another reason for this investigation is a suspicion that there may be an abnormality in the structure of the heart. |
| Stress Echo: | Occasionally, an echocardiogram is done while the heart is “under stress”. This is done by increasing the heart rate with either exercise or medication. This test can help to diagnose coronary heart disease, heart failure and cardiomyopathy. |
Reference: British Heart Foundation
This test is an ultrasound scan of the heart.
Jelly is applied to the bare chest to ensure good probe contact and an experienced operator will move the probe around the chest to gain good views of the heart. In particular, the ECHO can tell:
Images with thanks to Dr Ninian Lang, PhD, MRCP, Fellow in Advanced Heart Failure and Cardiac Devices, Scottish Advanced Heart Failure Service, Golden Jubilee National Hospital.
Definition: This test is also known as a stress test or exercise tolerance test (ETT) or treadmill test.
This is a variation on an ECG which records the activity of the heart as it works harder by walking on a treadmill. The exercise ECG records changes that the heart experiences due to an insufficient blood supply. It can be used to diagnose angina and assess severity, as well as ruling out cardiac causes for patient’s symptoms.
The following video from British Heart Foundation demonstrates a patient guide to an ETT.
To ensure the best quality ECG you should make sure the patient is relaxed. If the patient is tense this can affect the ECG, as muscle tremor can be misinterpreted. Remember, decisions are made based on this ECG reading.
Watch the ECG video clips and move through the slides using the < > controls below:
Patient demographics should be entered into the ECG machine prior to recording the ECG. Demographics should include: patient name, DOB/age, gender, ethnicity and CHI number. The demographics will aid accurate interpretation. Any symptoms at the time of recording should be noted e.g. chest pain. Any deviation from standard lead positions should be noted e.g. electrode placed on upper thigh due to above knee amputation. Also note if patient was not in a supine position during recording.
Ensure accurate anatomical chest lead positions – ALWAYS measure the intercostal spaces before placing chest electrodes. Don’t guess as bodies vary. Measuring the intercostal spaces correctly, before commencing, reduces the variances in ECG reading although it can be challenging.
The ECG gives a recording of the electrical activity of the heart in a graph form. Each lead gives a view of the electrical activity of the heart from a particular angle across the body. The ECG reflects what is happening in different areas of the heart and helps identify abnormalities.
The ECG is painless and takes around 5-10 minutes to perform.
The following video from Glasgow University demonstrates the recording of an ECG. (6 minutes 30 seconds)
The diagnosis/exclusion of hypertension can often be assisted by carrying out additional BP monitoring.
| Definitions | Indications |
|---|---|
| ABPM records a series of BP measurements, usually set at 30-minute intervals | Increasingly, to confirm hypertension diagnosis and whether drug treatment is needed (NICE, 2011); suspected ‘white coat’ hypertension (‘false’ BP stress response to clinic setting); or unusual BP variability. Felt to more accurately predict end-organ damage (e.g. left ventricular hypertrophy, chronic kidney disease) (SIGN, 2007) . Average value of at least 14 readings during the waking period used for hypertension diagnosis (NICE, 2011). |
| Definitions | Indications |
|---|---|
| Series of twice daily home BP recordings, over 7 days. Morning and evening measurements recommended, each taking average of 2 consecutive readings, 1 minute apart (NICE, 2011) | Used as alternative to ABPM. Useful if ABPM not tolerated or impractical (NICE, 2011). Requires a validated monitor suitable for home recording (details from British Hypertension Society website) |
Treat stage 1 hypertension, in line with guidance, if further assessment shows the following: left ventricular hypertrophy on the ECG; protein in urine; or retinal changes (like microscopic changes in the arterioles). Otherwise, monitor and ensure arrangements are made to review the patient (e.g. when are you arranging to see them again). Always treat stage 2 in line with guidance.
| Stage 1 hypertension: 135/85mmHg or higher | Stage 2 hypertension: 150/95mmHg or higher |
|---|
