EQUILIBRIUM GATED BLOOD POOL STUDY

INDICATIONS:

1. Assessment of cardiac function:

Left Ventricular ejection fraction (LVEF).

Right Ventricular ejection fraction (RVEF).

Chamber size.

Sequence of chamber contraction.

Chamber wall motion, including detection of akinetic and dyskinetic segments.

2. Detection of ventricular aneurysm.

3. Prospective evaluation prior to cardiac medications or drugs known to affect myocardial function (i.e. Adriamycin). Follow-up post-treatment.

4. Quantification of left-to-right intracardiac shunt (only with first pass technique).

5. Measurement of diastolic dysfunction.

6.Evaluation of valvular disease

PATIENT PREPARATION:

None.

RADIOPHARMACEUTICAL

The patient's own RBC's are labeled with Tc-99m. The 20-25 mCi given results in splenic radiation dose of 2.9 rad.

SCANNING TIME:

Labeling the RBC's with Tc-99m involves several steps and takes about 30 minutes. Once the tagged cells are injected, image acquisition can begin. This is "gated" to the cardiac cycle (EKG) and takes approximately 25 minutes. Longer times are required in patients with ectopic beats. Computer processing then takes 30-60 minutes to complete.

OTHER CONSIDERATIONS:

1. Imaging is linked to the cardiac cycle; images acquired during "aberrant beats" are rejected. Patients, therefore, with multiple aberrant ventricular beats require longer scan times to gather enough "good data". The study is not suited for patients with a markedly irregular heart rhythm.
2. Images are obtained in the LAO position that best demonstrates separation of both ventricles. In some cases additional image acquisitions may be required. A thorough history will help us to obtain the best possible study.
3. "First-pass technique" is only performed when specifically requested. It is a short duration study (<30 sec) that is useful for evaluation of RV function, pulmonary transit time, and intracardiac shunts (left-to-right). It is limited because only the first-pass of radioactive bolus is counted and spatial resolution may not be adequate to assess regional wall motion.
4. Pre-and post-stress examination can be done using a stationary bicycle.

RATIONALE:

Tc-99m labeled RBCs image the vascular pool and allow visualization of intracardiac blood flow. Scanning is linked to the EKG "R" wave and multiple systolic and diastolic images are obtained. These are summed and computer analyzed to generate the final images and quantitative data. The "first pass" technique is discussed above.

Functional images give valuable information about the synchrony and kinetic behavior of the walls of the left ventricle.

SOME NORMAL VALUES (for our Laboratory):

LVEF = > 50%

RVEF = > 40%

RI = .6 to 1.6