Participants in this study will undergo a series of adjustments to their pacemaker that will be made while you are in the intensive care unit recovering from your left ventricular assist device (LVAD) surgery. Participants will undergo these adjustments while still intubated (with a breathing tube left in after surgery) and sedated (in a medically-induced sleep) and the specific changes will involve increasing the rate that the pacemaker paces at and the leads (wires) that the pacemaker utilizes if more than one combination is available. While the pacemaker is set to pace at different, increasing heart rates, pressures will be measured in the different chambers of the heart utilizing a special type of intravenous (IV) line called a pulmonary artery catheter that will have been in place following the surgery. Several small blood samples will also be drawn from this venous catheter in order to measure oxygen levels in the blood. It will take approximately 30 minutes to perform the study, and when it is completed, the pacemaker will be returned to its original settings.

This research study aims to determine a less invasive way to assess heart function by taking measurements of the heart while subjects are performing an exercise cardiac MRI. Subjects will undergo two exercise phases and MRI measurements will be taken after each exercise phase. These measurements will be compared to available clinical data (including demographic, hemodynamic, radiologic, and functional) and future outcome data.

Elevated pressures in the heart can represent a severe medical condition known as pulmonary hypertension. This can result in chronic right heart failure. An abnormal increase in this pressure during exercise may be represent an early stage of vascular lung disease. This study will investigate the prognostic implications of the measured pressures obtained during exercise while undergoing a right heart catheterization procedure based on a large scale multi-center approach by using retrospective and prospective analysis of hemodynamic data.

This is an Open-Label extension of the parent study. The study will evaluate the safety and efficacy of levosimendan in PH-HFpEF subjects. All patients who enroll into this study received an open-label levosimendan. With the availability of oral levosimendan capsules, all consenting patients in TNX-LVO-05 will be transitioned to daily doses of oral levosimendan
and continue in the study for 3 years following transition to oral levosimendan or termination of the trial by the patient or physician decision.

Patients with systemic sclerosis (SSc) related pulmonary arterial hypertension (SScPAH) have a worse prognosis than those with idiopathic PAH. We have recently discovered that heart cells in SScPAH do not contract or squeeze as well as in other forms of pulmonary hypertension. However, the mechanism leading to this dysfunction is not understood. To better study this and in hopes of developing a future therapy, we plan to collect tissue samples via a heart biopsy at the time of a clinically indicated heart catheterization.