This technology includes a family of transcatheter endovenous intramyocardial tether (MIRTH) procedures to impose myocardial constraint on the LV (MIRTH), LV and RV (SCIMITAR), and cardiac resynchronization procedures. Included is a set of advanced cardiac treatment technologies that focus on minimally invasive procedures for heart patients. The main technology is the transcatheter endovenous intramyocardial tether (MIRTH) procedure, which is designed to apply physical constraint to the left ventricle (LV) of the heart. This method aims to aid in the treatment of certain heart conditions by altering the mechanical environment of the heart muscle. Additionally, the technology encompasses cardiac resynchronization procedures, which are used to improve the timing of the heart's contractions, particularly beneficial for patients with heart failure. Overall, these technologies represent a significant advancement in cardiac care, emphasizing less invasive methods to manage and treat complex heart conditions.