What is drug infusion testing?
Drug infusion testing is when medicine is given and seeing how the body reacts to the drugs. This is done in hospital and the patient is observed carefully. Drug infusion testing helps doctors learn the cause of certain symptoms and find things that may put a patient at risk. Once these are known, a specific and effective treatment plan can be created for the patient. It can also help to identify inherited problems, which gives people the option to get genetic tests and screening for family members.
During the test, a nurse will give the patient the drugs through an intravenous or IV. The heart will be monitored by an Electrocardiogram (ECG). The medicines used in these tests include adrenaline, procainamide, and isoproterenol.
Adrenaline is a hormone that is naturally produced in our body. Its purpose is to increase the supply of oxygen to the brain and muscles. It is the “fight or flight” hormone that is released into the bloodstream during stressful situations and some exercises. This hormone allows doctors to see how the patient’s heart reacts to stress. It can also help to detect a speeding or slowing in the heart’s electrical signal seen in some inherited conditions (Catecholaminergic VT, Long QT Syndrome).
Procainamide is a medicine that is commonly used to treat improper rhythms in the heart. It does this by slowing down the electrical signal of the heart. It can help to detect a delay in electrical activation in the heart that is seen in some inherited conditions (Brugada Syndrome, Long QT Syndrome).
Isoproterenol is a medicine that is used to speed up the heart in patients with heart slowing. In the past, this medicine was also used to treat asthma because it widens the airway to make breathing easier. In conditions where there is a slow impulse in the heart (Brugada Syndrome), it can normalize the delayed impulse.
How is the test done?
The first drug in the test is adrenaline. While it is given, the patient will be closely watched for any changes in heart. Once the test is finished, the patient will have a period of rest. Procainamide is the second drug given to the patient. As with the previous test, the patient will be carefully watched and monitored by an ECG. The ECG data will be studied for patterns and changes that may suggest a diagnosis, like Brugada Syndrome.
If certain changes are seen on the ECG, the isoproterenol infusion is given as the last step in the test. This gives doctors more information about the patterns and changes seen in the prior test.
What are the risks of drug infusion testing?
All medical procedures and treatments have risks. Patients may get a sense of their heart beating stronger or faster during adrenaline test, which is similar to what happens during exercise.
Patient may also get these side effects while getting the drug infusion test:
- Infection at the infusion or IV site
- Shortness of breath
- Irregular heart rhythm
The side effects will go away over a short period of time.