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Advice given for dealing with arrhythmias, AF in CTA
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ORLANDO, Fla. — Arrhythmias can have a tremendous effect on CT angiography image quality, and patients with atrial fibrillation should not be scanned because results can be unpredictable and image quality is often greatly degraded. However, data sets can often be salvaged, according to Stephan Achenbach, MD.
Achenbach is a professor of medicine in the department of cardiology at the University of Erlangen–Nurnberg, Germany.
“Available modern CT scanners allow physicians to obtain beautiful images, but they typically require a regular heart rate,” he said. “In many cases, it is possible to manipulate the electrocardiogram and the data reconstruction and remove the artifact caused by the ectopic beat.”
At the SCCT annual meeting in Orlando, he suggested the following:
Achenbach provided suggestions for dealing with artifacts caused by arrhythmias:
- Remove the trigger point of premature supraventricular contractions and/or premature ventricular contractions. (All CT scanners allow for manipulation of the ECG trace to remove or to add trigger signals.)
- It may be necessary to add additional triggers to the following diastole.
- Systolic triggering can be an alternative; sometimes data must be pieced together in diastole and systole.
- In patients with AF, good trigger instances are just before the R-wave or systole.
- Under all circumstances, avoid reconstructing the P-wave. – by Christen Haigh
Irregular rhythms remain an important consideration when performing noninvasive imaging. This is particularly true in studies such as CT, cardiovascular MRI and radionuclide imaging that require small variance in R-R intervals for the purpose of image construction. Developing methods to account for the variance introduced by rhythms such as AF remains an important area of research for imaging science.
– W. Gregory Hundley, MD
Cardiology Today Section Editor