What is Nuclear Cardiology?

Coronary heart disease is the leading cause of death in the United States. It accounts for more than 500,000 deaths each year. Early diagnosis and treatment can mean the difference between life and death for many. Over the past 20 years, advancements in the field of cardiology have made use of nuclear materials to help with the diagnosis and treatment of heart disease.

Identification

Nuclear cardiology involves the use of specialized imaging processes, and radioactive materials to diagnose the health, and functional ability of the heart. Radioactive materials are administered by injection, or pill. Once they reach the heart, special cameras are used to photograph the structures and processes taking place inside the heart. Areas of the heart that are not receiving adequate blood supply become visible under the imaging camera.

Features

The radioactive materials used are made of radioactive isotopes, which are atoms that have been destabilized. A destabilized atom is an atom that has a missing proton, or neutron. A proton, or neutron is dislodged by colliding the atom with another atom, or by using a high-powered light ray. When a proton or neutron is dislodged from an atom's center, an enormous amount of energy is released. This dispersed energy is how the cameras track what's going on inside the heart.

Significance

Chemical interactions play a role in how radioactive isotopes behave inside the body. Different parts of the body attract certain chemicals, and this is what determines what type of isotope is used. As most atoms in the body are stable atoms, they will attract destabilized atoms to them. The absence or presence of certain chemicals within the heart will attract (or not attract) the isotope material into specific areas. The cameras are then able to provide information on the physical make-up of the heart depending on where the isotope goes.

Types

There are three different techniques used within nuclear cardiology. Myocardial perfusion is the most commonly used method where patients are required to perform a stress test before pictures of the heart are taken. A radioactive imaging agent like thalium, or tetrofosim is injected into the blood prior to the stress test to see how the heart functions when it's at rest. A treadmill is then used to observe heart function during activity. Gamma cameras are used to record the heart's processes.
Radionuclide ventriculography is a second technique use to photograph how blood circulates through the heart's chambers. Once the imaging agent is injected into the bloodstream, gamma cameras provide information as to which areas of the heart are blocked, and which ones have good circulation.
Positron emission tomography is the third technique, used to examine blood supplies and metabolic activities within the heart. Images taken can show scarring from past heart attacks, and determine how damaged a particular area may be. This technique is also used to evaluate the heart's nervous system which provides information on areas that are not responding normally.

Function

The procedures used within nuclear cardiology provide information that would could otherwise only be obtained through surgery. Specialized imaging techniques make it possible to find blocked areas within the heart, assess the amount of damage an area has suffered, and determine the likelihood of recovery for a particular area without the need for exploratory surgery.
The heart's nervous system function determines the health of the heart beat. Electrical impulses within the heart can be damaged by heart attacks, or arteriosclerosis. The chemical make-up of the radioactive agents used can reveal what areas of the heart are misfiring. Combining results from a myocardial perfusion test and a positron emission tomography gives doctors the information needed to determine if surgery is necessary.

Resources

• Isotope Stress Test Information
• American Society of Nuclear Cardiology Site