|  | Conditions Treatments | Heart Disease

Dipyridamole & Cardiolite Protocol

A doctor may have prescribed a pharmacological stress test because of a decreased capacity for exercise and the need to capture an image of the blood flow in your heart. While an exercise stress test requires the patient to increase his heart rate by using a treadmill, the dipyridamole and cardiolite protocol artificially increases the heart rate. The radioactive nucleotide in cardiolite allows technicians to use nuclear imaging to visualize the blood flow in your heart.

  1. The Components

    • Dipyridamole is a vasodilator that inhibits the reuptake of adenosine, increasing blood flow in the heart. This medicine increases the heart rate and thus the blood flow into the heart. In combination with the radionucleotide cardiolite, it is possible to raise a patient's heart rate and image the functional capacity of the heart valves with nuclear imaging. Cardiolite is minimally radioactive and has a half-life of six hours.

    Who Should and Should Not Be Tested

    • Patients with limited physical capacity due to injury, arthritis, orthopedic problems or cardiovascular disease are candidates for pharmacologic stress testing. Patients who have a ventricular pace maker should be tested with dipyridamole and cardiolite, since traditional exercise stress tests produce false-positive perfusion defects in the interventricular septum, or the appearance of a leak between the ventricular chambers. Since exercise stress tests aim to raise the heart rate, any patients taking beta-blockers or other medicines to regulate heart rate should be tested by pharmocological means to achieve accurate results.

    Contraindications

    • Do not take any methylzanthines, like caffeine or aminophylline, at least 24 hours prior to your appointment. These drugs compete for adenosine receptors, decreasing or blocking the effects of the dipyridamole. Patients experiencing bronchospasm, being treated for bronchospasms or suffering from other breathing difficulties such as asthma or COPD should not undergo the dipyridamole and cardiolite protocol. Patients with a systolic blood pressure lower than 90 mmHg should not use dipyridamole because it could further decrease blood pressure. Women who are pregnant or trying to become pregnant should only undergo cardiolite testing if absolutely necessary. Cardiolite is a Category C drug with no animal or human trials to indicate the short- or long-term effects of radiation on the fetus. Cardiolite radiation focuses most strongly in the tissue of the ovaries, and its temporary or long-term effects on fertility are unknown.

    The Test

    • Fast for four to six hours before the test. You will receive an intravenous injection of cardiolite and be instructed to return 90 minutes later for radioimaging. The first set of images provide the technicians with a resting or baseline image of the blood flow in your heart. Next, you will be attached to an electrocardiogram (ECG) to monitor your heart rate before and during the pharmacological stress test. Throughout the testing the technician will also monitor your heart rate. A phlebotomist will insert an IV for administration of the dipyridamole. The dipyridamole must be administered slowly over approximately four minutes. Side effects after the injection include dizziness, decreased blood pressure and chest pain. After initial monitoring to ensure that you have no adverse side effects, the technician will administer another injection of cardiolite. Return in one hour for a final imaging.

Heart Disease - Related Articles