What is a pharmacological test?
Pharmacologic stress testing is a medical examination that evaluates the heart’s response to the injection of certain medications.
By subjecting the heart to simulated situations that reproduce certain physiological reactions, such as an acceleration or slowing of the heart rate, pharmacologic stress testing can be used to help diagnose anomalies or evaluate ongoing treatments.
What are the various pharmacological tests?
Depending on the patient’s symptoms, various pharmacologic provocation tests may be proposed.
Isoproterenol test:
This test is designed to reproduce a situation of intense stress or an emotion, even though the patient is comfortably lying down. This painless test results in an increased heart rate in response to an isoproterenol infusion over a period of three minutes, which could be potentially uncomfortable. By the end of the first minute, the patient starts to feel their heart beating faster. To reduce discomfort, it is essential to breathe normally, calmly and regularly, without following the frenetic pace of the heart. Some possible unpleasant feelings include tingling in the fingers, sweating and perhaps even nausea.
Once the test is completed, the heart rate will be monitored for approximately 20 minutes, and, following medical advice, the patient will be able to eat and drink after roughly one hour.
Ajmaline test:
The bodies of patients are easily able to tolerate the ajmaline test, which lasts five minutes. Most patients do not feel any particular sensation, although some experience a slight metallic taste in their mouth. A follow-up electrocardiogram will be performed approximately four hours after the test is completed to make sure that everything is okay.
Adrenaline test:
This test is quick and easy, and is performed in two five-minute sessions. Adrenaline makes the heart beat slightly faster, but most patients do not feel any particular effects during the test.
ATP (adenosine triphosphate) test:
The ATP test only lasts a few seconds but can be unpleasant. The aim is to temporarily slow the heart rate, which can make the patient feel as though they are in a rapidly dropping elevator. Sometimes the physician will ask the patient to cough during the test to speed the heart up again.
Why undergo pharmacologic stress testing?
Pharmacologic stress testing may be recommended in several situations in order to better understand certain symptoms or to narrow down a diagnosis:
- Identify the origin of the symptoms: If the patient is experiencing unexplained discomfort, palpitations or loss of consciousness, pharmacologic stress testing can help identify the cause of these symptoms by reproducing certain conditions so as to observe how the heart reacts.
- Clarify abnormalities on the electrocardiogram (ECG): During systematic work-ups (surgery, routine examination, or family screening), abnormalities may appear on the ECG without being able to make a clear diagnosis. Pharmacologic stress testing can then confirm or rule out a suspicion of an underlying pathology.
- Evaluate the risk of heart rhythm disorders: If a pathology has already been identified via a resting electrocardiogram, the test can be used to more precisely evaluate the risk of developing heart rhythm disorders related to this pathology.
- Treatment monitoring: Pharmacologic stress testing is sometimes used to measure the effectiveness of an ongoing treatment, especially within the context of heart conditions, and to adjust or guide the therapeutic management.
What happens during pharmacologic stress tests?
The patient is placed in a specially equipped room to ensure their safety. An IV line is placed in the patient’s arm for the purpose of injecting the required medications. Throughout the test, an ECG is used to continuously record the patient’s heart rate. The patient stays still in a lying down position so that a high-quality ECG recording is obtained. The entire process is supervised by a physician and a nurse to ensure optimal medical monitoring throughout the test.
How to prepare for pharmacologic stress tests
Before undergoing pharmacologic stress testing, it is important that the patient is fasting, i.e. that they have not had anything to eat or drink or have not smoked for at least six hours. This preparation is key to making sure that the test runs smoothly and to avoid any interference.
Are pharmacologic stress tests dangerous?
Pharmacologic testing carries certain risks, as with any examination involving the use of pharmacological substances.
Potential risks include:
- heart rhythm disorders (such as an accelerated heart rate, electrocardiogram changes, or ventricular arrhythmias) which are sometimes accompanied by the re-occurrence of the patient’s usual symptoms.
- allergic reactions to one of the substances administered
To minimize these risks, strict safety measures are put in place at each stage: before, during and after the tests are performed. However, these tests provide crucial data that cannot be obtained using other methods.
