Nuclear medicine combines computers, detectors and radioactive substances called radioisotopes to produce images of blood flow and biochemical functions in the heart and other organs. What makes the procedure so valuable is that it is possible to obtain the required information without disturbing the normal bodily functions.
Ever since the introduction of nuclear medicine in diagnosis, it has been possible to identify any structural and functional abnormality in various organs.
It has now been demonstrated for the first time that an experimental radioactive compound can show images of heart damage up to 30 hours after a brief interruption of blood flow and oxygen.
The heart normally uses fatty acid as its primary fuel source for energy. Decreased blood flow to the heart, caused either by narrowed or clogged arteries or increased demand on the heart during strenuous exercise, sets off a metabolic disturbance that slows down or halts the way fatty acid is normally utilized. The condition is called myocardial ischemia. The disturbance causes the heart to switch from fatty acid as its primary fuel to glucose.
The new tracer test keys in on this metabolic disturbance and seemingly remembers the imprint of an episode of reduced blood flow long after the episode, a process that is called "ischemic memory. When the heart is being imaged, there is a representation of the reduced fatty acid metabolism that aids diagnosis.
The radioactive tracer evaluated for this study, known by the brand name Zemiva, links a fatty acid to a radioisotope which is injected in the patient. The researchers used a technique called SPECT (Single Photon Emission Computed Tomography) to evaluate the tracer in this study.
The discovery may help physicians in emergency rooms and in their offices determine whether a patient's chest pain, which may have subsided hours earlier, is related to heart disease or something else, such as indigestion.
This probe provides a direct connection to the cause of the chest pain without requiring a treadmill stress test or use of a drug that produces stress to assess heart function, according to researchers. Additional testing will be required before this new agent can be approved by the U.S. Food and Drug Administration.