An independent provider of cardiovascular health care

In association with Phoenix Hospital Group

Tests and Diagnostics

Blood Tests

Almost all patients undergoing any form of cardiac assessment will need some baseline blood tests:

These tests may include:

  • Electrolytes (sodium and potassium levels)
  • Urea and Creatinine (kidney function)
  • Blood Count (test for anaemia)
  • Liver tests
  • Glucose and HBA1C (test for diabetes)
  • Lipid profile (Cholesterol and triglycerides)
  • Thyroid Function
  • BNP (test for heart failure)
  • Troponin (test for heart attack)
  • Genetic tests

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Chest X-Ray

A chest X-Ray is often performed as a first line fairly routine test in patients with symptoms that could be coming from the heart or lungs. It can give an approximate idea of the size of the heart but importantly it can tell your doctor about the lungs including fluid overload due to impaired cardiac function and intrinsic lung problems.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Electrocardiogram (ECG)

This is one of the most basic cardiac investigations and involves putting stickers (electrodes) on the skin to detect the electrical impulses of the heart. Typically the stickers will be put on the arms, legs and chest. This is known as a ’12 lead ECG’. It is entirely painless and can often tell your cardiologist some basic information about the rhythm and condition of your heart.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Echocardiogram

Routine ‘Transthoracic’ Echocardiogram

‘Transoesophageal’ Echocardiogram or ‘TOE’

Diagnostic transthoracic ultrasound scanning ‘TTE’ is harmless and performed using a transducer (Probe) which is placed on the chest with jelly which improves the images. This scan looks directly at the structure of the heart, its chambers and valves. In addition it can give valuable information about the flow of the blood. Sometimes the echo images will be enhanced with either a contrast agent or a bubble study.

Transoesophageal echo (TOE) is similar in concept to a transthoracic echo ‘TTE’ however it uses a very small transducer fitted to a flexible probe which is passed into the oesophagus (gullet) using local anaesthetic and if necessary mild sedation or occasionally under general anaesthetic. This test is particularly good for looking at the structure of valves of the heart since the heart lies very close to the gullet in the chest allowing high resolution images.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Holter Monitor

The ECG provides a ‘snapshot’ in that it records the electrical activity of the heart for a few heartbeats whilst the recording is being made. This has obvious limitations for heart rhythm problems that come and go in a ‘paroxysmal’ fashion rather than a sustained rhythm abnormality.

If a patient is getting palpitation every day, then a 24 hour tape recording will be able to show the cardiologist how the heart is behaving during symptoms (which should be recorded with the time on a diary card). If the symptoms are less frequent then a 48 hour, 5 day or one week monitor might be helpful.

Duration of monitor will vary according to the frequency of the rhythm disturbance or palpitation

It may also be useful to determine the ‘burden’ (ie frequency) of a known rhythm problem.

If the problem is rare-but potentially serious it is sometimes helpful use a ‘patient activated’ device or even to surgically implant a small recording device for several months to establish what the problem is.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Ambulatory Blood Pressure (ABPM)

24 Hour Ambulatory Blood Pressure Measurement (ABPM) uses a blood pressure cuff, memory card and small battery driven pump

Blood pressure measurements made in the doctors surgery are useful but do have some limitations. They are really only a ‘snapshot’ of your blood pressure and can also be influenced by anxiety (white coat effect).

A series of home blood pressures performed using an automatic blood pressure monitor can be helpful and can give useful information.

When making important decisions about blood pressure management and drug treatment however a 24 hour recording is usually considered the most thorough approach. A 24 hour ambulatory blood pressure monitor (ABPM) typically measures your blood pressure every regularly for a 24 hour period. This reduces the ‘white coat effect’ and usually gives more reliable information on which to base decisions.

It is important to be aware however that ABPM usually gives a lower BP than surgery readings and allowance needs to be made for this when looking at thresholds for treatment and measuring adequacy of treatment.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Exercise Test

The resting ECG looks at the electrical activity of the heart when the patient is lying comfortably and therefore doesn’t test the heart under load. The exercise test allows the cardiologist to see how the heart performs under load. Although the exercise test has some limitations it can be useful in screening, assessing exercise capacity, in the investigation of patients with chest pain and for some other indications such as heart rhythm problems. Exercise is usually on either a treadmill or exercise bike and performed with ECG electrodes connected. The blood pressure is measured frequently during the test.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Cardiopulmonary Exercise Test (CPET)

This test is similar to the exercise ECG in that involves the same exercise with continuous ECG monitoring and blood pressure measurements. The important difference is that the exercise ECG is focussed principally on the heart. The cardiopulmonary Exercise Test (CPET) is more ’holistic’. It examines multiple causes of exertional breathlessness, be they due to the heart, the lungs or indeed problems of general conditioning and can often differentiate between these. CPET can also be used to evaluate fitness levels in athletes, and to assess patients capacity to tolerate surgical operations. CPET achieves these aims by measuring the oxygen consumption and expired carbon dioxide levels during exercise.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Myocardial Perfusion Scan

Whilst the CTCA scan and coronary angiogram give anatomical information about the coronary arteries and any possible narrowing, Myocardial Perfusion Scanning (MPS, Myoview, Thallium scan) looks at the functional uptake of blood by the heart muscle and by implication the coronary blood supply to the heart. This is achieved by exercising the heart either with physical exercise (eg treadmill or exercise bike) or in some situations by using a drug infusion to increase the heart rate.

In Myocardial Perfusion Scans a small dose of a radioisotope is injected into a vein and images of the heart are observed using a special scanner (gamma camera) following exercise ‘stress’ and at rest. The basic principle of the test is to look at whether tracer uptake is reduced in the stress image which can suggest limitation in blood supply to the heart and the possible need for further tests. A further useful function of myocardial perfusion scanning is in planning for operations since it is a non-invasive way of assessing the potential cardiac risk of non-cardiac surgery.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Stress Echo

Whilst the CTCA scan and coronary angiogram give anatomical information about the coronary arteries and any possible narrowing, stress echo looks at the functional performance of the muscle of the heart and by implication the coronary blood supply to the heart. This is achieved by exercising the heart either with physical exercise (eg treadmill or exercise bike) or in some situations by using a drug infusion to increase the heart rate. Stress echo does not use ionising radiation.

In Stress Echo the performance of the heart muscle is evaluated following exercise ‘stress’ and at rest. Failure of the muscle of the heart to pump harder during stress can suggest limitation in blood supply to the heart and the possible need for further tests.

A further useful function of stress echo scanning is in planning for operations since it is a non-invasive way of assessing the potential cardiac risk of non-cardiac surgery.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

MRI Scan

Magnetic Resonance Imaging (MRI) scanning of the heart has moved on considerably in recent years and has moved from being a fairly rare test to use to a much more routine examination. The scan does not use ionising radiation.

MRI scanning provides excellent high resolution images of the structure of the heart and in particular allows the cardiologist to evaluate the muscle of the heart.

Although MRI is not routinely used to evaluate the anatomy of the coronary arteries (for which CTCA and coronary angiography are superior) stress perfusion MRI can give functional information about coronary artery perfusion and is growing in popularity.

MRI has a number of other strengths and is also a very good test for examining the thoracic and abdominal aorta.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

National Heart Lung and Blood Institute

CT Scan

CT scanning of the heart has developed considerably in recent years and is now a very valuable investigation. It is important to understand the difference between Coronary CT Calcium Scoring (a screening test which can help establish the presence of coronary artery disease and help with cardiovascular risk assessment) and CT Coronary Angiography (CTCA -a high resolution scan establishing the presence or absence of coronary artery disease and evaluating the significance or severity of any coronary artery narrowing that might be present).

National Heart Lung and Blood Institute

Calcium scoring uses a lower radiation dose and doesn’t require any needles or injections. CTCA does expose the patient to more radiation and requires an intravenous injection of an iodine containing contrast medium however it gives more information.

Both tests are of value and guidance will be needed form your cardiologist about whether a CT scan is needed and the relative merits of the two methods for an individual patient.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Cardiac Catheter

This test is also known as a diagnostic coronary angiogram or sometimes abbreviated to just ’cardiac cath’ or ‘angio’. It is the ‘gold standard’ test for looking at the coronary arteries. Cardiac catheters can be performed as a purely diagnostic procedure, or combined with an angioplasty and stent procedure.

Cardiac catheterisation is performed by passing a long tube or catheter into the coronary arteries and injecting an iodine containing ‘contrast’ medium liquid so that the inside or ‘lumen’ of the arteries can be seen on an x-ray machine in real time. The access to the blood vessels is through a small ‘sheath’ introduced via the femoral artery (groin) or radial artery (wrist). At the end of the procedure the sheath is withdrawn and bleeding is stopped by pressing or using a ‘vessel closure’ device.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Electrophysiological Study (EPS)

If patients are suffering from problems with the heart rhythm or are considered to be at high risk of serious heart rhythm problems it is sometimes useful to study the electrical behaviour of the heart in more detail that that afforded by the ordinary ECG. EPS is performed in the cardiac catheter laboratory and electrodes are passes on long catheters through the veins in the groin into the heart. These wires are then used to study how the electricity travels in the heart in its normal rhythm, and during a palpitation where possible known as ‘mapping’. It may be necessary to use electrical stimulation to elicit an abnormal rhythm as part of the procedure. EPS can be performed as a diagnostic procedure or sometimes combined with treatment, by performing an ablation.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Carotid Ultrasound and IMT

Ultrasound of the carotid arteries (the arteries in the neck supplying blood to the brain) is undertaken for two reasons.

Firstly, in patients who have had a stroke or transient ischaemic attack (TIA) or in whom there is a clinical suspicion of problems with blood flow to the brain, an ultrasound or ‘carotid Doppler’ may be recommended. This is to look for severe narrowing of the arteries that might require treatment with surgical ‘endarterectomy’ or stenting.

An second application however relates to screening. The carotid arteries are very superficial and represent a part of the cardiovascular system which is very easy to access with ultrasound.

National Heart Lung and Blood Institute

Since cardiovascular disease also known as hardening of the arteries or atherosclerosis usually occurs diffusely throughout the vascular system, a scan of the carotid arteries allows one to look at a ‘window’ of the condition of the arteries.

This is potentially very useful because if there is any evidence of atheroma or hardening of the arteries, we should go to great lengths to prevent further progression and the possibility of cardiovascular events in the future.

All test results should be treated with caution and interpreted in the context of a clinical assessment.

Abdominal Aorta Ultrasound

Atherosclerosis usually causes narrowing (stenosis) of arteries however it can also cause bulging or dilatation of arteries (aneurysms). Abdominal aortic aneurysm (AAA)-bulging of the main artery in the abdomen is a particularly important type of aneurysm because if it ruptures it needs emergency treatment and can be fatal, however AAA develops over many years and if found through screening it can be monitored and often treated electively either with a surgical repair or using a covered stent passed through a catheter when appropriate.

Screening for AAA has been shown to be of benefit in certain patient groups and as such forms an important part of an overall cardiovascular screening program.

The abdominal aorta can be scanned in detail using ‘body scans’ such as CT and MRI which give a very accurate assessment however AAA can also be screened for using simple abdominal ultrasound.

National Heart Lung and Blood Institute

If there is evidence of AAA on screening then if the aneurysm is small, regular scans will usually be recommended. If the aneurysm is large then it may be appropriate to consider repairing it.

This treatment may often be lead by a vascular surgeon but might also involve an interventional radiologist or cardiologist if a stent is being considered. Preventive therapies will also be important to reduce as much as possible the risk of future cardiovascular events.

All test results should be treated with caution and interpreted in the context of a clinical assessment.