Abstract 3084: Bare Metal Stenting versus Percutaneous Pulmonary Valve Implantation for Treatment of Right Ventricular Outflow Tract Obstruction - Utilization of a Catheter/Magnetic Resonance Hybrid Lab for Acute Physiological Comparison

Abstract

Background: Treatment of right ventricular outflow tract obstruction (RVOTO) is possible with a bare metal stent (BMS), though this causes pulmonary regurgitation (PR). In this study, we sought to assess the acute physiological effects of BMS vs. percutaneous pulmonary valve implantation (PPVI) using a catheter/ magnetic resonance (MR) hybrid lab (Siemens). Methods: 12 consecutive children (median age 12.9) with significant RVOTO (echo gradient > 50 mmHg) were included. Patients were initially placed in the MR scanner and the ventricular volumes and great vessel blood flow assessed under general anaesthetic (GA). Patients were then transferred into the bi-plane catheter lab (under the same GA, on a sliding table) and a BMS inserted. Catheters and wires were removed and patients were transferred back to MR for repeat assessment. This whole process was repeated for a PPVI, which was placed into the BMS. MR and pressure data were compared with repeated measures ANOVA and post-hoc testing between the 3 physiological states. Results (see Table ): BMS placement significantly reduced RV pressures and caused free PR. The increased PR was partially compensated for by a decrease in RV ESV and an increase in RV EF. There was no improvement in effective RV SV after BMS placement. Re-valvulation with PPVI resulted in a significant increase in effective RV SV, with consequent heart rate reduction at maintained cardiac output. Conclusion: Utilisation of a catheter/MR hybrid lab offers new opportunities for the assessment of acute physiology following percutaneous interventions. Using this method we have demonstrated the superior acute haemodynamic effects of PPVI over BMS in patients with RVOTO.