Comparison of Bare Metal Stenting and Percutaneous Pulmonary Valve Implantation for Treatment of Right Ventricular Outflow Tract Obstruction Use of an X-Ray/Magnetic Resonance Hybrid Laboratory for Acute Physiological Assessment

Background-Treatment of right ventricular outflow tract obstruction is possible with a bare metal stent (BMS), although this treatment causes pulmonary regurgitation. In this study, we assessed the acute physiological effects of BMS versus percutaneous pulmonary valve implantation (PPVI) using an x-ray/magnetic resonance hybrid laboratory. Methods and Results-Fourteen consecutive children ( median age, 12.9 years) with significant right ventricular outflow tract obstruction underwent BMS followed by PPVI. Magnetic resonance imaging ( ventricular volumes and function and great vessel blood flow) and hemodynamic assessment ( invasive pressure measurements) were performed before BMS, after BMS, and after PPVI; all were performed under general anesthesia in an x-ray/magnetic resonance hybrid laboratory. BMS significantly reduced the ratio of right ventricular to systemic pressure (0.75 +/- 0.17% versus 0.41 +/- 0.14%; P<0.001) with no further change after PPVI (0.42 +/- 0.11; P=1.0). However, BMS resulted in free pulmonary regurgitation ( 21.3 +/- 10.7% versus 41.4 +/- 7.5%; P<0.001), which was nearly abolished after PPVI (3.6 +/- 5.6%; P<0.001). Effective right ventricular stroke volume ( right ventricular stroke volume minus pulmonary regurgitant volume) after BMS remained unchanged (33.8 +/- 7.3 versus 32.6 +/- 8.7 mL/m(2); P=1.0) but was significantly increased after revalvulation with PPVI (41.0 +/- 8.0 mL/m(2); P=0.004). These improvements after PPVI were accompanied by a significant heart rate reduction (75.5 +/- 17.7 bpm after BMS versus 69.0 +/- 16.9 bpm after PPVI; P=0.006) at maintained cardiac output (2.5 +/- 0.5 versus 2.4 +/- 0.5 versus 2.7 +/- 0.5 mL . min(-1) . m(-2); P=0.14). Conclusion-Using an x-ray/ magnetic resonance hybrid laboratory, we have demonstrated the superior acute hemodynamic effects of PPVI over BMS in patients with right ventricular outflow tract obstruction. ( Circulation. 2009; 119: 2995-3001.)