A functionally integratable catheter system (FICS) capable of mechanical actuation for treating chronic total occlusions, comprising: a support catheter; a mechanically actuatable dilator; a PTA catheter; and a lock-grip handle, wherein the support catheter comprises: (i) a shaft member, a manifold member, and a female luer lock adapter capable of connecting to the lock-grip handle; (ii) a straight-edged distal end for an interoperable design; and (iii) a central lumen capable of receiving (a) a mechanically actuated dilator; or (b) a PTA catheter for enhancing maneuverability; wherein the lock-grip handle is configured to coaxially receive a shaft member of (a) the mechanically actuated dilator or (b) the PTA catheter, when the lock-grip handle is pre-assembled with the support catheter; characterized in that the lock-grip handle comprises: (i) a pushing handle formed by a shaft locking handle, a proximal connector element, and a compressible seal; (ii) a shaft-locking mechanism enabled by an engagement of the shaft member (132, 142) of the mechanically actuated dilator or the PTA catheter by the compressible seal contained in the pushing handle; (iii) a spring-loaded actuation mechanism formed by an external casing member enclosing an upper cam body, a lower cam body, and a spring element, the external casing member attached to the pushing handle; wherein the shaft-locking mechanism and the spring-loaded actuation mechanism enhance at least one of (a) the positional control over the dilator tip, (b) the extension range of the PTA catheter balloon member, and (c) the tip propagation of the dilator or the PTA catheter; wherein the support catheter, the mechanically actuatable dilator, the PTA catheter, and the lock-grip handle are selectively configurable in situ by a clinician operator enabling several therapeutic-specific configurations for each phase of a multi-staged angioplasty procedure; wherein the PTA catheter comprises a balloon member of constant length concentrically concealed within the distal end of the support catheter in an uninflated state, and wherein the PTA catheter exhibits a variable usable length during operability; and wherein the support catheter, the mechanically actuatable dilator, and the PTA catheter are each dimensionally adaptable in vivo for interoperability for lesion-length selective treatment. a support catheter; a mechanically actuatable dilator; a PTA catheter; and a lock-grip handle, wherein the support catheter comprises: (i) a shaft member, a manifold member, and a female luer lock adapter capable of connecting to the lock-grip handle; (ii) a straight-edged distal end for an interoperable design; and (iii) a central lumen capable of receiving (a) a mechanically actuated dilator; or (b) a PTA catheter for enhancing maneuverability; (i) a shaft member, a manifold member, and a female luer lock adapter capable of connecting to the lock-grip handle; (ii) a straight-edged distal end for an interoperable design; and (iii) a central lumen capable of receiving (a) a mechanically actuated dilator; or (b) a PTA catheter for enhancing maneuverability; wherein the lock-grip handle is configured to coaxially receive a shaft member of (a) the mechanically actuated dilator or (b) the PTA catheter, when the lock-grip handle is pre-assembled with the support catheter; characterized in that the lock-grip handle comprises: (i) a pushing handle formed by a shaft locking handle, a proximal connector element, and a compressible seal; (ii) a shaft-locking mechanism enabled by an engagement of the shaft member (132, 142) of the mechanically actuated dilator or the PTA catheter by the compressible seal contained in the pushing handle; (iii) a spring-loaded actuation mechanism formed by an external casing member enclosing an upper cam body, a lower cam body, and a spring element, the external casing member attached to the pushing handle; (i) a pushing handle formed by a shaft locking handle, a proximal connector element, and a compressible seal; (ii) a shaft-locking mechanism enabled by an engagement of the shaft member (132, 142) of the mechanically actuated dilator or the PTA catheter by the compressible seal contained in the pushing handle; (iii) a spring-loaded actuation mechanism formed by an external casing member enclosing an upper cam body, a lower cam body, and a spring element, the external casing member attached to the pushing handle; wherein the shaft-locking mechanism and the spring-loaded actuation mechanism enhance at least one of (a) the positional control over the dilator tip, (b) the extension range of the PTA catheter balloon member, and (c) the tip propagation of the dilator or the PTA catheter; wherein the support catheter, the mechanically actuatable dilator, the PTA catheter, and the lock-grip handle are selectively configurable in situ by a clinician operator enabling several therapeutic-specific configurations for each phase of a multi-staged angioplasty procedure; wherein the PTA catheter comprises a balloon member of constant length concentrically concealed within the distal end of the support catheter in an uninflated state, and wherein the PTA catheter exhibits a variable usable length during operability; and wherein the support catheter, the mechanically actuatable dilator, and the PTA catheter are each dimensionally adaptable in vivo for interoperability for lesion-length selective treatment.