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 . <EOS>