Structural Integrity of Mechanical Heart Valve Rings During Valve-in-Valve Interventions.

• Mechanical valve rings fracture only at supraphysiologic pressures. • Pyrolytic carbon rings show limited expansion and no meaningful diameter gain. • Structural constraints limit precise prediction of post–valve-in-valve hemodynamics. • Risk of inadvertent ring damage during leaflet fracture appears low. • Findings define biomechanical limits of transcatheter valve-in-valve in mechanical heart valves.