A bendable medical instrument comprising: a handle at a proximal end of the bendable medical instrument; a modular distal shaft including a plurality of vertebrae, wherein the modular distal shaft is configured to bend at the vertebrae and is situated near a distal end of the bendable medical instrument; a bendable internal rod disposed through at least some of the plurality of vertebrae, the bendable internal rod having a modular cell structure; and a distal tip coupled to the modular distal shaft at the distal end, wherein the modular distal shaft is configured to bend at the plurality of vertebrae to position the distal tip in a patient and the bendable internal rod is configured to bend with the modular distal shaft at the plurality of vertebrae, wherein the distal tip comprises a deployable component and the handle comprises a deployable component control knob configured to provide at least one of control over a degree of deployment of the deployable component and measuring of the degree of deployment of the deployable component, wherein the deployable component includes a valve annulus sizing device comprising: a holder having a proximal end and a distal end, the proximal end of the holder being coupled to the modular distal shaft, a hub member rotationally coupled to the bendable internal rod and rotatably mounted into a central chamber of the holder, a measuring band having a first end and a second end, the first end of the measuring band being coupled to the holder, and the second end of the measuring band being coupled to the hub member, wherein the measuring band is wound about the holder and extends through a slot of the holder to the hub member. a handle at a proximal end of the bendable medical instrument; a modular distal shaft including a plurality of vertebrae, wherein the modular distal shaft is configured to bend at the vertebrae and is situated near a distal end of the bendable medical instrument; a bendable internal rod disposed through at least some of the plurality of vertebrae, the bendable internal rod having a modular cell structure; and a distal tip coupled to the modular distal shaft at the distal end, wherein the modular distal shaft is configured to bend at the plurality of vertebrae to position the distal tip in a patient and the bendable internal rod is configured to bend with the modular distal shaft at the plurality of vertebrae, wherein the distal tip comprises a deployable component and the handle comprises a deployable component control knob configured to provide at least one of control over a degree of deployment of the deployable component and measuring of the degree of deployment of the deployable component, a holder having a proximal end and a distal end, the proximal end of the holder being coupled to the modular distal shaft, a hub member rotationally coupled to the bendable internal rod and rotatably mounted into a central chamber of the holder, a measuring band having a first end and a second end, the first end of the measuring band being coupled to the holder, and the second end of the measuring band being coupled to the hub member, wherein the measuring band is wound about the holder and extends through a slot of the holder to the hub member.