13N-Ammonia PET Can Visualize Improvement of the Left Ventricular MFR by Transcatheter Pulmonary Valve Implantation.

The patient was a woman with repaired tetralogy of Fallot. Cardiac magnetic resonance revealed right ventricular enlargement and severe pulmonary regurgitation, and we performed a transcatheter pulmonary valve implantation. Preoperative 13N-ammonia positron emission tomography indicated myocardial flow reserve (MFR) was reduced, but postoperative MFR improved to within the normal range. The increased forward flow due to pulmonary regurgitation improvement may have increased the output; the improved left-right ventricular interaction due to decreasing right ventricular load and volume reduction may have contributed to the increase in MFR. These findings indicate 13N-ammonia positron emission tomography visualizes MFR improvements by transcatheter pulmonary valve implantation.