A system for the treatment of conditions affecting the mitral valve, comprising an interventional device for deployment upon and/or along the mitral valve comprising: a proximal stabilizing structure having a first pair of arm members (16A, 16B) pivotably joined to a proximal engagement link, and wherein each arm member of the first pair of arm members is further pivotably joined to a respective joining member of a first pair of joining members (18A, 18B), wherein each joining member of the first pair of joining members (18A, 18B) is pivotably coupled to an arm member of a second pair of arm members (20A, 20B) via a respective link of a first pair of links (34A, 34B), wherein each arm member of the second pair of arm members is further coupled pivotably to a respective joining member of a second pair of joining members (22A, 22B), and wherein each joining member of the second pair of joining members (22A, 22B) is further pivotably coupled to a middle engagement link; and a distal stabilizing structure having a third pair of arm members (26A, 26B), wherein each arm member of the third pair of arm members is pivotably coupled to a respective joining member of a third pair of joining members (28A, 28B) via a respective link of a second pair of links (38A, 38B), wherein each joining member of the third pair of joining members (28A, 28B) is pivotably coupled to a respective arm member of a fourth pair of arm members (30A, 30B) pivotably joined to a distal engagement link, wherein each of the arm members of the third pair of arm members (26A, 26B) is further pivotably coupled to a respective joining member of a fourth pair of joining members (24A, 24B), and wherein each joining member of the fourth pair of joining members (24A, 24B) is pivotably coupled to the middle engagement link; wherein the distal and proximal stabilizing structures (14, 12) are pivotably coupled via the engagement link such that the distal and proximal stabilizing structures (14, 12) are configurable between an axially-elongated configuration and a laterally-elongated configuration. a proximal stabilizing structure having a first pair of arm members (16A, 16B) pivotably joined to a proximal engagement link, and wherein each arm member of the first pair of arm members is further pivotably joined to a respective joining member of a first pair of joining members (18A, 18B), wherein each joining member of the first pair of joining members (18A, 18B) is pivotably coupled to an arm member of a second pair of arm members (20A, 20B) via a respective link of a first pair of links (34A, 34B), wherein each arm member of the second pair of arm members is further coupled pivotably to a respective joining member of a second pair of joining members (22A, 22B), and wherein each joining member of the second pair of joining members (22A, 22B) is further pivotably coupled to a middle engagement link; and a distal stabilizing structure having a third pair of arm members (26A, 26B), wherein each arm member of the third pair of arm members is pivotably coupled to a respective joining member of a third pair of joining members (28A, 28B) via a respective link of a second pair of links (38A, 38B), wherein each joining member of the third pair of joining members (28A, 28B) is pivotably coupled to a respective arm member of a fourth pair of arm members (30A, 30B) pivotably joined to a distal engagement link, wherein each of the arm members of the third pair of arm members (26A, 26B) is further pivotably coupled to a respective joining member of a fourth pair of joining members (24A, 24B), and wherein each joining member of the fourth pair of joining members (24A, 24B) is pivotably coupled to the middle engagement link; wherein the distal and proximal stabilizing structures (14, 12) are pivotably coupled via the engagement link such that the distal and proximal stabilizing structures (14, 12) are configurable between an axially-elongated configuration and a laterally-elongated configuration.