Abstract 2193: Percutaneous Pulmonary Valve Implantation for Right Ventricular Outflow Tract Obstruction Enhances Cardiac Response to Exercise by Improved Bi-ventricular Stroke Volume
Background - Magnetic resonance imaging (MRI) often guides the management of patients with congenital heart disease involving right ventricular outflow tract (RVOT) dysfunction. However, the impact of RVOT dysfunction, and its relief, on cardiac response to exercise stress is unknown.
Methods - 10 patients, who underwent percutaneous pulmonary valve implantation (PPVI) for significant RVOT obstruction (echo gradient >50mmHg), were included. MRI was performed at rest and during supine exercise stress at the same intensity pre- and within 1 month post-PPVI. Bi-ventricular volumes and function were assessed during free breathing and continuation of exercise using a radial k-t SENSE real-time sequence. Pulmonary regurgitation fraction was calculated as follows: RV stroke volume (SV) - LV SV. Results (see Table⇓) - Prior to PPVI, augmentation of cardiac output during exercise was mainly achieved by increased heart rate, with only slight increases in RV and LV effective SV. After relief of RVOT obstruction by PPVI, augmentation of RV and LV SV during exercise improved significantly compared to the assessment pre-PPVI. This was achieved by increasing RV ejection fraction and LV end-diastolic volume. This improved RV and LV SV augmentation during exercise resulted in heart rate reduction at maintained cardiac output compared to the response to exercise seen prior to PPVI.
Conclusion - PPVI for RVOT dysfunction improves bi-ventricular response to exercise. Utilisation of such real-time MR imaging techniques during exercise stress may refine the assessment of procedural success post RVOT interventions in patients with congenital heart disease.