This study is enrolling subjects with heart failure and a preserved fraction meaning the heart is too stiff to fill properly to meet the body's needs. This study is researching an investigational device (study device) called the Alleviant ALV1 System. Investigational means it has not been approved for commercial use by the Food and Drug Administration. (FDA) This study will test the safety and effectiveness of the Alleviant ALV1 System. The Alleviant ALV1 System is intended to create a shunt (an opening) in the heart to allow for proper blood flow through the heart which may improve your symptoms. No device is left in your heart it is just used to create the shunt. This is a randomized study which means subjects are assigned by chance to either have the study device create this shunt or not have the study device create the shunt. Randomization is 50/50 meaning there is a 50% chance to have the study device create a shunt and a 50% chance the study device will not be used. Using the study device to create the shunt is performed during a right heart catheterization (RHC) so all subjects will undergo the RHC but only 50% will have the shunt. Neither the subjects nor the study doctor will know which group subjects are randomized to but other study staff will know in the event this information is needed. All subjects will stay overnight in the hospital after the procedure. Other study related procedures include echocardiograms - ultrasound test of the heart, electrocardiograms (ECG) - a tracing of the heart's electrical activity, blood work, questionnaires, 6 minute hall walk test, and assessments of heart failure status. Risks include risks related to the study device including blood vessel damage from placing the device in the vein to get to the heart, risks from the right heart catheterization such as bleeding or bruising, abnormal heart beats, and risks related to study related procedures. There may be risks that are not known at this time. Participation in this study is expected to last about 60 months and include approximately 15 in person visits and 3 telephone calls.