Gating errors on cardiac nuclear stress testing

Case contributed by Dr Jayanth Keshavamurthy

Presentation

Cardiac nuclear testing performed as a preoperative assessment for renal transplant.

Patient Data

Age: 75 years
Gender: Male

Abnormal cardiac gated stress test

Nuclear medicine

1. Technologist should have noticed that there is a gating problem. 

2. The examination should have been converted to a non-gated stress test.

3. See the ratio of accepted to rejected heartbeats. 

4. This test should not have been post-processed.

5. On reporting- it was reported as the most abnormal stress test ever seen.

6. On an immediate, subsequent echocardiogram the ejection fraction (EF) was normal.

7. Troubleshooting was performed and the gating error was found.

The patient was called back for a repeat stress test and another unnecessary radiation exposure.

Repeat study with improved cardiac gating

Nuclear medicine

1. On repeat study the QA parameters are so different. Gating errors are usually due to atrial fibrillation and PVC's. But sometimes the ECG leads and connections can be faulty.

2. EF now matches with the echo findings.

3. No ischemia, the slightly fixed decreased counts in the apex are likely from apical thinning.

 

Case Discussion

A very important lesson to always look at the QA page first to look for gating errors.

If the number of rejected beats are high the ejection fraction in a nuclear stress test may not be as accurate as the echocardiographic ejection fraction.

Do not expect your technologist to catch all the errors.

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