NHLBI SESAME (SEptal Scoring Along Midline Endocardium) Early Feasibility Study

Background: Some people have a condition in which the wall (septum) that separates the two main pumping chambers of the heart is too thick. This thick septum causes a condition called "left ventricular outflow tract obstruction" (LVOTO), which reduces blood flow out of the heart. LVOTO can cause serious heart disease; symptoms may include shortness of breath, chest pain, heart failure, or death. Researchers want to find better ways to treat LVOTO. Objective: To test a new procedure where excess tissue is sliced away from the septum in people with LVOTO. This procedure is called "septal scoring along midline endocardium" (SESAME). Eligibility: Adults aged 21 years with LVOTO. Design: Participants will have baseline tests. They will have imaging scans and tests of their heart structure and function. They will take a walking test and answer questions about how their heart condition affects their life. Participants will stay in the hospital 2 to 6 days for the SESAME procedure. They will be completely or partially asleep for the procedure. A tube will be inserted into the mouth and down the throat to take pictures of the heart. Pictures may also be taken with a tube inserted inside the heart. Next, tubes will be inserted into the groin and guided through the blood vessels up to the heart. Guidewires will be inserted into the heart. Doctors will watch the path the wires take with x-rays and ultrasound. When the wire is in the correct place, it will be electrified to slice excess tissue away from the septum. Participants will have 3 follow-up visits within 1 year.