A strategy to shorten VT treatment and improve precision
Date: December 26, 2011
Electrical mapping of the heart to locate areas responsible for ventricular tachycardia (VT) is a long and laborious process. CT images of the heart are acquired beforehand to convey the shape and dimensions of the cardiac chamber, but those images do not show areas of diseased tissue where the abnormal rhythms may be coming from. So during the procedure, the tissue is meticulously probed to find low voltage areas that signal the presence of scar tissue.
To shorten the treatment time and improve precision, electrophysiologist Saman Nazarian is studying a new strategy. He’s using high-resolution cardiac MRI to locate in advance the scar tissue—the likely origination point of the abnormal electrical activity—before the patient comes in for the ablation procedure. The idea is to make mapping and therefore the treatment time shorter and also to deliver more precise therapy.
“After the patient has the MRI scan, we use special software to localize and highlight areas of scar tissue on the MRI image. We then import that previously acquired image of scar tissue and merge it with real-time catheter positions defined by fluoroscopy during the ablation procedure. This scar map is then used to guide us to areas of the heart most likely to generate the short circuit that causes VT,” says Nazarian, who is leading a clinical study on the new approach.
In the NIH-funded study, called Standard Ablation vs. MRI-Guided Ablation in the Treatment of Ventricular Tachycardia, patients are randomly assigned to have either the MRI-guided VT ablation or the standard procedure.
“When we know in advance where the scar tissue is located,” says Nazarian "we can cut the procedure time for patients, exposing them to less radiation and less catheter manipulation looking for ablation targets inside the heart.”