Hello thanks for your query. As you havent mentioned details, I assume you are talking about the heart of your fetus, where the left chambers are underdeveloped. If this is the case, it is called - Hypoplastic left heart syndrome (HLHS) - one of the most challenging congenital heart defects to care for. A diagnosis of HLHS through prenatal cardiac ultrasound enables you to plan to treat your newborn immediately after delivery. The family and medical team should plan for delivery at, or next to, a cardiac center that’s equipped to care for the newborn, such as: a children’s hospital with an adult or obstetric hospital attached or very near, or a medical center that has obstetric facilities coupled with neonatal/pediatric cardiac facilities. At first, a newborn with HLHS may appear normal. But symptoms usually develop in the first few hours or days of life. Lack of vital blood flow causes the baby to go into profound shock, endangering the brain, liver, kidneys and other vital organs. Symptoms may include: rapid breathing or shortness of breath rapid heartbeat or pounding heart poor suckling and feeding cold extremities (poor perfusion) blue color of the skin, lips and nailbeds (cyanosis) lethargy Your child will need at least three staged surgeries in his first few years of life.Children with hypoplastic left heart syndrome will need follow-up care throughout their lives to ensure that their hearts continue to function adequately. Most children will also need heart medication(s). Complications going forward can include arrhythmias (abnormal heart rhythms), heart failure, blood clots, and a few other rare problems. Yes, the treatment is expensive. Please consult your obstetrician and a Fetal Medicine specialist for how to proceed ahead. take care.