Invasive Tests

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Some of the tests listed below are carried out regularly with someone who has CHD but some are carried out once or not at all. It all depends on the individual or should we say that it all depends of the complexity of the CHD.

Some tests can involve chemicals being injected into the body – invasive – or readings taken externally only – non-invasive.   On this page we are concentrating on Invasive Tests, for non-invasive tests click here

Aortography (aortographic a·or’to·graph’ic [-t?-graf'ik])

Aortography is a an examination of the aorta and its branches by using radiographic visualization (x-rays). An injection using a dye called contrast media (radiopaque substance) which contains iodine and is opaque to x-rays.  This is done using percutaneous puncture or catheterization procedures.  So, basically the dye is injected into an artery through a needle or thin plastic tube which is called a catheter and x-rays are then taken.  With the dye in the arteries showing up on the x-ray thus any narrowing or blockage will be seen.  This will allow the surgeon to decide if an operation is necessary and he can then plan any details of how the blockage can be dealt with.

Arteriography showing coarctation of the aorta at the typical site (arrows) and a saccular dilatation of the proximal left subclavian artery)

Coronary angiogram – cardiac catheterisation

Cardiac catheterisation is often used to assess whether people with angina require surgery.
The test gives vital information about blood pressure within the heart, how much oxygen is in the blood, the function of the pumping chambers and valves, and the exact severity and positioning of any narrowings in the coronary arteries.

A coronary angiogram - a picture of the coronary arteries

The catheter – a long, flexible, plastic tube – is inserted into a vein or artery in the groin or the arm after a local anaesthetic is given.
The catheter is used to inject dye into the coronary arteries – this is called coronary angiography or coronary arteriograpy.
High speed X-ray “films” record the course of the liquid as it flows through the heart and arteries. Obstructions in the arteries can be identified by tracing the liquid’s passage.

Cerebral arteriography is used to show the extent and location of hardening of the arteries in the brain in order to diagnose patients at risk of stroke.
The test takes between 20 minutes and an hour and is often done as day case, though some patients may have a short stay in hospital.
There is a very small risk – one in 700 – that the test will cause a heart attack.

Electrophysiologic Study (EPS)

An electrophysiology (EP) study is a test that records the electrical activity and the electrical pathways of your heart (the system that generates the heart beat). This test is used to help determine the cause of your heart rhythm disturbance and the best treatment for you. During the EP study, your doctor will safely reproduce your abnormal heart rhythm and then may give you different medications to see which one controls it best or to determine the best procedure or device to treat your heart rhythm.

Electrophysiologic study (EPS) of the heart is done by threading thin plastic tubes (catheters) into a vein where the leg connects to the abdomen. A local anesthetic is given as well as a mild sedative. The procedure is not painful and the patient is not put to sleep. After being placed into the vein, the catheters are then passed under fluoroscopic guidance into the heart. These catheters measure the electrical signals generated by the heart. They can be a much more detailed analysis of these signals than a simple electrocardiogram (ECG). The catheters are used to rapidly pace the heart — to make the heart beat quickly.

The electrical conduction system of the heart is also measured during this rapid pacing and the heart is observed to see if any abnormal heart rhythms develop.

The reason for doing EPS may to determine:

  • If a person needs a pacemaker. (This can usually be decided without an EPS but once in a while EPS is necessary.)
  • Why a person is fainting (if other tests to find a basis have failed to find one).
  • If a person is prone to a fast heart rhythm (tachycardia) and guide the appropriate treatment for this abnormal heart rhythm (arrhythmia).
  • Whether past treatment for a fast heart rhythm has been satisfactory

Nuclear imaging

A very small and harmless quantity of radioactive substance, called an isotope, is injected into the blood, often while exercising.
Gamma rays emitted by the isotope – usually technetium or thallium – are picked up by a “camera” positioned close to the chest.
Technetium is used to test the size and pumping function of the heart chambers, taking pictures of the inside of the heart as it empties and fills.

Thallium is used to study the blood flow to the heart muscle, by taking pictures of the flow of blood to the muscular walls of the heart, and to provide more detailed information than the exercise ECG test.

Transesophageal echocardiography, or TEE/T.O.E

The transesophageal echocardiogram (TEE/T.O.E) is an alternative means of producing echocardiograms of the heart. It carries more risk than the standard
echocardiogram procedure (which is essentially risk-free), but is still quite safe and under the right circumstances can be extremely useful.

As opposed to the standard echocardiogram, in which the transducer is placed over the chest wall, in TEE/T.O.E the transducer is passed into the esophagus (the swallowing tube) and is positioned directly behind the heart.

To do the procedure, the patient is sedated, and the gag reflex is suppressed by spraying a local anesthetic into the back of the throat. The transducer is then passed through the mouth and throat, and down the esophagus.

Once in position directly behind the heart, the transducer bounces sound waves off the heart (just as in the standard echocardiogram), and images of the
cardiac structures are produced.

Related Links:

BBC – Medical Notes
www.medterms.com
www.webmd.com
www.about.com
www.surgerydoor.co.uk
www.nlm.nih.gov

Disclaimer: The facts and opinions shown in this article are as accurate and up to date as possible, but are provided as general “information resources”, which may not be relevant to individual persons. This article is not a substitute for individual assessment and always take advice from a doctor who is familiar with the particular person..

Consult your child’s physician regarding the specific outlook for your child.