Valve Interventions in Utero: Understanding the Timing, Indications, and Approaches.

Efficient use of fetal echocardiography has enabled early detection of congenital heart disease and of its often irreversible complications, such as ventricular hypoplasia in case of severe stenosis of the semilunar valves. Experience of the past 25 years has proved that balloon dilatation of the severely stenotic or atretic valve in fetuses as early as the 23rd week of gestation is technically feasible with a learning curve. Reported results regarding the ultimate biventricular circulation outcome after fetal valve intervention are at best controversial, with the desired improvements in the quality of life and cost-benefits of the postnatal treatment being as yet unconfirmed. Despite acute hemodynamic success with a relatively low rate of fetal complications, the number of suitable candidates for the fetal valve intervention remains low. High valvular tissue plasticity in the fetus and difficulties of assessing the point of no return of the myocardial damage often makes the success of fetal valve intervention short-lived and unpredictable. Hopefully, future refinements of the equipment, imaging, and biodegradable tissue regeneration materials will lead to better results of the fetal valve interventions beyond their technical success.