Diagnostic Tests

Cardiology  

Electrocardiogram (ECG) 

What it is and how it works: An electrocardiogram (ECG) is one of the most common heart tests performed. It is used to record the electrical activity of the heart during each beat, which is done by placing a number of electrodes, or sticky pads, onto the chest, wrists, and ankles. These are then connected by wires to an ECG recording machine. It is important that the patient remains as relaxed as possible during the ECG recording to help ensure a reliable result. Normally, the test will last for only a few minutes. 

What it detects: An ECG can help to identify various heart problems. It can be used to detect unusually fast or slow heart rates, irregular heart rhythms (also called arrhythmias), and areas of reduced blood supply to the heart. 

Blood pressure 

What it is and how it works: A blood pressure test is used to measure the strength, or pressure, of blood against the walls of the arteries of the body. This pressure is caused by the pumping action of the heart. Blood pressure is usually recorded as two numbers – the systolic pressure, which is the maximum pressure generated when blood is pumped out of the heart during a single beat, and the diastolic pressure, which is the minimum pressure between beats, or when the heart is at rest. For example, a blood pressure of 140 systolic over 90 diastolic is recorded as 140/90mmHg. When a recording of your blood pressure is made, a cuff will usually be wrapped around the upper arm and filled with air until tight – this can feel a little uncomfortable. The cuff is connected to a blood pressure machine which will help to record the result. It is important to remain as relaxed as possible and not to talk during the test. This helps to ensure a reliable result. Normally, the test will last for only a few minutes. 

What it detects: Blood pressure recordings help to detect abnormally high or abnormally low results. High blood pressure is typically linked to unhealth lifestyles, consuming too much alcohol, smoking, or being overweight. If left untreated, it can lead to problems with the heart and kidneys. Low blood pressure can be caused by certain medicines, dehydration, and heart failure.  

24-hour blood pressure monitoring 

What it is and how it works: As with a blood pressure recording, an inflatable cuff is secured around your arm. However, for 24-hour blood pressure monitoring, this cuff is then connected to a small monitoring device that is worn around your waist. The cuff will inflate and deflate at regular intervals over a 24-hour period to help monitor your blood pressure. You will not need to stay in the hospital or clinic for this to be done, and you can continue with your normal day-to-day activities during this. 

What it detects: As with blood pressure assessment, blood pressure recordings help to detect abnormally high or abnormally low results.  

Tilt table test 

What it is and how it works: A tilt test is used to recreate symptoms of dizziness or fainting in a controlled and safe environment. This can help to identify the underlying cause. Before starting the test, a number of electrodes, or sticky pads, will be placed onto the chest, wrists, and ankles. These are connected to an ECG machine to monitor heart rhythm and rate. A blood pressure cuff will also be wrapped around the upper arm or finger. You will then be asked to lie flat on a special bed for five minutes. The bed will then begin to tilt upwards into an almost upright position and will either continue for 20 minutes or until you begin to feel dizzy or faint. If you feel unwell, a medicine called glyceryl trinitrate will be sprayed under the tongue. The test is then continued for a further 15 minutes. Once the test is complete, you will be allowed to sit upright and given a glass of water. The full length of an appointment will usually last between one to two hours. 

What it detects: A tilt test is used to detect causes of fainting such as vasovagal syncope. It is usually performed in patients who experience dizzy spells or fainting. 

Chest X-ray 

What it is and how it works: A chest x-ray is a quick and painless investigation used to take black and white images of the heart, lungs, and bones. It works by passing x-rays, a type of radiation, through the body to a detector (or photographic plate) at the back. While dense structures such as bones appear white, softer structures such as the heart and lungs appear dark. Sometimes, images will be taken from different angles to better visualise the organs of the body. Usually, the whole process will only take a few minutes. 

What it detects: A chest x-ray can be requested if a doctor thinks that the cause of your symptoms might be due to a lung or heart issue. It can help to detect problems with the lungs, such as pneumonia or lung cancer, or problems with the heart, such as heart failure. It can also be done as part of routine work up for an operation. 

Cardiac computed tomography (CT) and CT coronary angiogram 

What it is and how it works: A cardiac CT is an investigation that uses x-rays to take detailed images of the heart. Unlike a chest x-ray, which produces a 2D image, a cardiac CT produces a 3D image. When a cardiac CT test is used to evaluate the arteries that supply blood to the heart, this is called a CT coronary angiogram – a specialized type of CT test. This can help to identify any narrowing or blockages (coronary artery disease) that might be the cause of your symptoms. 

What it detects: A cardiac CT can be requested to help investigate certain problems of the heart, such as congenital heart disease, valve defects, blood clots, tumors, or a buildup of lipid plaque in the arteries that surround the heart. 

Cardiac magnetic resonance imaging (cardiac MRI) 

What it is and how it works: A cardiac MRI is an investigation used to take high-resolution images of the heart using a powerful magnet. Unlike a chest x-ray or CT scan, an MRI does not use x-rays. However, it is very important to remove any metal objects before having the test. During a cardiac MRI, you will be asked to lie down on a table before being moved inside of the machine. It can get quite noisy during the test, however you will be provided with headphones or given the option to listen to some music. You may be asked to hold your breath for some images too. It is also important to remain as still as possible to prevent the final images from being blurred. Although scan times may vary, a cardiac MRI may last from about 30 minutes to over an hour. 

What it detects: A cardiac MRI can be requested to help diagnose a range of heart problems, such as coronary heart disease, inherited heart conditions like hypertrophic or dilated cardiomyopathy, and valvular heart disease. 

Myocardial perfusion scan 

What it is and how it works: A myocardial perfusion scan is an imaging test used to investigate how well the heart is able to pump blood. It also looks at the flow of blood through the heart itself. During the test, a small amount of radioactive substance is used. This travels through the blood and is absorbed by healthy heart tissue. Areas of unhealthy or damaged tissue, or areas with poor blood flow, do not absorb the radioactive substance. On imaging, these areas will therefore appear as ‘cold spots’. Often, the test is performed after some gentle exercise to see how well the heart copes under stress. 

What it detects: A myocardial perfusion scan is used to find out the cause of unexplained chest pain or pain that is caused by exercise. It can see whether the arteries supplying the heart are narrowed or blocked and can help to determine the extent of damage after a heart attack. 

Echocardiogram 

What it is and how it works: An echocardiogram, or echo, is a painless and non-invasive test used to investigate the structure and function of the heart. It looks at the heart valves, heart chambers, and blood vessels. It uses sounds waves (or ultrasound) that are emitted from a probe onto the body, and that are then reflected off from the muscles and tissues of the heart to create a moving picture. The most common type of echocardiogram performed is called a transthoracic echocardiogram. This is where a lubricating gel and probe are placed onto the chest and moved around to produce an image. This is then displayed onto a monitor. Other types of echocardiogram include a transoesophageal echocardiogram, which is where a probe is passed down the oesophagus (food pipe), or a stress echocardiogram, which is done to see how well the heart works under stress. Usually, the whole test takes between 15 minutes to an hour. 

What it detects: An echocardiogram can help detect a variety of conditions. These include damage from a heart attack, problems with the heart valves such as infection in the case of endocarditis, or heart failure – this is where the heart is unable to pump enough blood around the body. 

Bubble echo 

What it is and how it works: A bubble echocardiogram is a test that involves injecting salt (saline) water bubbles into the blood stream to see whether they stay within the correct side of the heart or not. A normal heart should retain the bubbles within the right chamber (atrium). If the bubbles leak into the left side, this indicates that there might be a structural problem with the heart. During the test, a small drip containing the saline bubbles will be attached to your arm. You will also be connected to an ECG. An ultrasound will be applied to your chest to help take images of your heart. Once the saline bubbles have been injected, your doctor will observe how the solution fills the heart. Usually, the test takes around 30 minutes. 

What it detects: A bubble echocardiogram is a test to help diagnose a patent foramen ovale or an atrial septal defect. These are also referred to as congenital heart defects. 

Heart monitor 

What it is and how it works: A heart monitor is a device that can be used to continuously monitor your heart rate and rhythm for 24 hours or longer. This can help detect any irregular beats that might not have been picked up during a routine ECG because they occur on an infrequent basis. When given a heart monitor, the monitor itself can be attached to a waistband, or put in a pocket, and a number of stickers will be placed on your chest. The most common type of heart monitor is a Holter monitor – this can be worn for between 1 to 7 days, depending on what your doctor recommends. Usually, it takes around 30 minutes to be fitted with a heart monitor. 

What it detects: A heart monitor device can help diagnose unexplained dizziness or fainting, heart palpitations, and atrial fibrillation. 

Implantable loop recorder 

What it is and how it works: An implantable loop recorder (ILR) is a small heart monitor that is placed under the skin, usually on the left side of the chest, through a minor operation. It is used to record the electrical activity of the heart for up to three years and to detect any heart rhythm or rate irregularities. This information is then recorded and stored for your doctor to review. Once a diagnosis has been made, or the battery of the ILR has come to an end, the device will be removed in a similar way to when it was first implanted. Usually, the procedure to fit an ILR will take around 10 to 15 minutes. 

What it detects: An implantable loop recorder may be recommended by your doctor if your symptoms cannot be explained after a routine ECG. These symptoms may include dizzy spells, blackouts, or palpitations. 

Cardiopulmonary exercise test 

What it is and how it works: An exercise stress or cardiopulmonary exercise test is used to assess the function of the heart and lungs during increased levels of activity. It involves walking on a treadmill, or riding a stationary bike, while your blood pressure, ECG, and breathing are recorded. During the test you will gradually exercise at a faster speed and a greater incline to make your heart and body work faster. This will usually go on for a total of 12 to 15 minutes. Although not painful, sometimes your symptoms might be brought on by exercise – it is important to tell your doctor if this happens. You should also wear comfortable clothes and trainers during the day of your test. Usually, the test will take about 30 minutes. 

What it detects: An exercise stress test can be used to detect coronary artery disease. If your test shows an abnormal heart rhythm or that the heart’s blood supply is insufficient, your doctor might recommend further tests. 

Six-minute walk test 

What it is and how it works: A six-minute walk test is used to assess the ability of the heart and lungs to respond to six minutes of self-paced walking. During this, you will be asked to walk a distance that is covered over a six-minute time frame. You will also be fitted with a monitor and a pulse oximeter on your finger (to monitor oxygen saturation during the test). The test is entirely self-paced, and you will be asked to walk between two cones and to do as many laps as you can manage. There will also be chairs available for you to rest if needed.  

What it detects: A six-minute walk test is used to evaluate the level of physical activity of a person, and to evaluate exercise tolerance in people with respiratory diseases.  

Electrophysiological study 

What it is and how it works: An electrophysiological (EP) study is a minimally invasive test that looks at the electrical activity of the heart. During the study, a thin flexible tube (a catheter) will be inserted into a vein, usually in the groin. This is then passed up to the heart where your doctor will try to stimulate and diagnose an abnormal heart rhythm. It can also help to identify which parts of the heart are affected. The results of this study will help your doctor to decide whether you need a medicine, a cardiac device, or catheter ablation to manage the condition. During the test, you might feel chest discomfort or palpitations – it is important to tell your doctor if this happens. Usually, the test will take about 2-3 hours. 

What it detects: An EP study helps to diagnose a variety of abnormal heart rhythms and to predict the risk of sudden cardiac death. 

Blood tests 

What it is and how it works: A blood test is where a sample of blood is taken for analysis in a laboratory. This is done by inserting a needle into a vein, usually at a site that is located inside the elbow or on the back of the hands. Before the needle is inserted, a tight band (tourniquet) is placed above the site from which the blood is due to be drawn. The skin is then cleaned with an antiseptic wipe. Once the required number of samples have been taken, these will then be sent to a laboratory for tests. 

What it detects: Several blood parameters can be looked at during a blood test. These include a Full Blood Count (FBC – to look for infection or anaemia), Urea and Electrolytes (U&Es – to look for any electrolyte imbalances), Liver Tests (to look for any liver problems), Lipid Profile (to look for any abnormalities in cholesterol, good and bad fat levels, as well as performing an advance lipid profile for e.g., familiar hypercholesterolaemia), Thyroid Function Tests (TFTs – to look for an over or underactive thyroid which can cause problems with the heart, or that might be resulting in palpitations), Clotting Screen (to monitor medicines such as warfarin), Cardiac Enzyme Tests such as troponin (to diagnose or rule out a heart attack), B-type Natriuretic Peptide (BNP – to look for signs of heart failure), and inflammatory markers such as ESR/CRP (for pericarditis and myocarditis) 

Respiratory 

Ambulatory oxygen therapy assessment 

What it is and how it works: Ambulatory oxygen is a therapy used in patients whose oxygen levels become low during periods of increased activity. This can be caused by some diseases of the lungs and can lead to a patient feeling exhausted quicker than usual as well as an inability to do much before needing to stop. Ambulatory oxygen therefore works by delivering additional oxygen to the muscles of the body whilst active to keep them going for longer. Assessment for therapy involves your doctor asking you a number of questions such as those related to your levels of mobility, and you will be asked to perform a six-minute walk test. During this you wear a probe on your finger to help monitor your blood oxygen levels. The information from these tests will allow your doctor to determine whether ambulatory oxygen therapy is suitable for you. 

What it detects: Ambulatory oxygen therapy assessment is used to detect low blood oxygen levels during increased physical activity, which might be due to a disease of the lungs. 

Allergy skin test 

What it is and how it works: Allergies are when the immune system reacts to a particular food, substance, or material – this is called an allergen. Examples of these include tree pollen, dust mites, nuts and shellfish, as well as insect bites and stings. During an allergic reaction, symptoms such as sneezing, coughing, wheezing, and rashes can happen. Allergies are common in the UK, particularly in children, and there are a number of ways to test for these. These can include skin prick testing and patch tests. These tests involve placing a small amount of the suspected allergen onto the skin and then waiting a specific duration of time to see whether a reaction happens or not. 

What it detects: Allergy skin tests help to detect things, such as foods, substances, or materials, that a patient might be allergic to. 

Arterial blood gas analysis 

What it is and how it works: An arterial blood gas (ABG) is a test that is used to measure the acidity (pH), oxygen, and carbon dioxide levels of arterial blood. It is used to assess the function of the lungs, kidneys, as well as the ability of the body to maintain a normal metabolic state. During the test, a needle will be inserted into an artery in the wrist to collect a sample of blood. This may cause some pain however it should fade away quickly after the test. Usually, an ABG will take only a few minutes to complete, and the results will be available shortly after. 

What it detects: An ABG is used to detect problems with the lungs such as COPD or issues with the kidneys such as kidney failure.  

Lung function test 

What it is and how it works: A lung function test is a non-invasive investigation used to determine how well the lungs work and whether there are any functional problems. There are several different tests that can be performed. These include spirometry, single breath gas transfer, and body plethysmography. During a full test, you will be asked to breathe into and out of a mouthpiece, which is connected to a machine that records the result. These tests will help to determine the speed at which air can be breathed in and out of the lungs, how well oxygen is able to travel from the lungs into the blood, and the total size or volume of air in the lungs. Usually, the test will take about 30 minutes to an hour.  

What it detects: A lung function test helps to look for lung disease such as COPD. It may also be performed before you are due to undergo an operation.  

Spirometry 

What it is and how it works: Spirometry is a common test used to diagnose and monitor conditions that affect the lungs. It does this by assessing how well your lungs work when breathing in and out. It is performed by using a device called a spirometer, which is connected by a cable to a mouthpiece. During the test, a soft clip will be placed on your nose to prevent any air from escaping. You will then be asked to breathe in as much as possible and to breathe out into the mouthpiece. The test will normally be repeated at least three times to ensure a reliable result. Usually, the test takes about 30 to 90 minutes. 

What it detects: Spirometry can be used to diagnose and monitor asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis, and pulmonary fibrosis. 

Peak flow measurement 

What it is and how it works: A peak flow is a test that measures how quickly air can be blow out of the lungs. This is done to detect and monitor certain changes such as narrowing of the airways. During the test, you will be given a small hand-held device called a peak flow meter. It is important to make a tight seal around the mouthpiece of the device in order to ensure a reliable result. When ready, you will be asked to breathe out as fast and as quickly as possible. Three attempts will usually be made, and the best score will be recorded. If your peak flow reading shows signs of a narrowed airway, your doctor may request additional tests such as spirometry. Usually, a peak flow test is quick and painless and will only last for a few minutes. 

What it detects: A peak flow can be used to diagnose conditions such as asthma and to monitor this condition over time. This will help your doctor to decide what medicines or management to recommend. 

Sleep study 

What it is and how it works: A sleep study is a non-invasive overnight test used to collect information about the way in which the body functions while sleeping. An overnight stay is required to complete this study. During the test, a recording of your oxygen levels, breathing, and movements will be made and monitored on a computer. This is done by attaching a small sensor to your finger, between the nose and upper lip, and by placing a few on the chest and abdomen. These sensors are then removed the following morning. Overall, most patients are able to enjoy a normal night’s sleep and the test itself is painless. 

What it detects: A sleep study can help to diagnose problems such as sleep apnoea, which is when there are pauses in breathing during sleep.  

Computed tomography (CT) pulmonary angiography (CTPA) 

What it is and how it works: A computed tomography (CT) pulmonary angiogram (CTPA) is a test that uses x-rays to look at the flow of blood to the lungs if there is suspicion of a clot. It involves injecting a special contrast dye into a blood vessel of the body, typically in the arm or groin, to help visualise the blood vessels. Usually, the test will take about 30 minutes to two hours.  

What it detects: A pulmonary angiogram can be used to investigate blood flow to the lungs, to look for any abnormal blood vessel narrowing, or to check and treat any blood clots – for example, in the case of a pulmonary embolism. 

Bronchoscopy 

What it is and how it works: Bronchoscopy is a procedure that looks at the trachea (windpipe), branches of the airways, and some parts of the lungs. This is done by using a bronchoscope, which is a long flexible tube, that is passed down through the nose or mouth. Images can then be taken to look for the presence of any abnormalities. Sometimes a biopsy, or a small sample of tissue, can be taken for analysis in a laboratory. During the procedure you will be given a sedative through a vein and your throat will be sprayed with an anaesthetic to help you relax. Usually, the procedure will last for around 30 minutes to an hour. 

What it detects: Bronchoscopy can be used to detect lung cancer, to remove blockages such as food, to take biopsies for further investigation, or to deliver radiation (brachytherapy).