Extending his inventiveness to his familys medical problems, Benjamin Franklin invented the flexible catheter in 1752 when his brother John suffered from bladder stones. Franklins catheter was made of metal with segments hinged together with a wire enclosed to provide rigidity during insertion.According to a footnote in his letter in Volume 4 of the Papers of Benjamin Franklin (1959), Franklin credits Francesco Roncelli-Pardino from 1720 as the inventor of a flexible catheter. In fact, Franklin claims the flexible catheter may have been designed even earlier.An early modern application of the catheter was employed by Claude Bernard for the purpose of cardiac catheterization in 1844. The procedure involved entering a horses ventricles via the jugular vein and carotid artery. This appears to be an earlier and modern application of the catheter because this catheter approach technique is still performed by neurosurgeons, cardiologists, and cardiothoracic surgeons.David S. Sheridan invented the modern disposable catheter in the 1940s. Prior to this, some reusable catheters consisted of braided cotton tubes, which were varnished, heat-treated and polished. As these were primarily produced in France, the advent of World War II threatened the supply chain.In 1959, Teschan first described central venous catheter as means of blood vessel access for haemodialysis.Other reusable catheters consisted of red rubber tubes. Although sterilized prior to reuse, they still posed a high risk of infection and often led to the spread of disease.
Catheters used in interventional procedures
Polyimides are used to manufacture vascular catheters for insertion into small vessels in the neck, head and brain.Guiding catheters (catheters that guides angioplasty balloons and stents) is made up of polytetrafluoroethylene (PTFE) innermost layer which is lubricant, followed by stainless steel braid wire outer layer which helps to provide support for the catheter and prevent kinking while travelling through blood vessels, and Nylon elastomer outermost layer which provides extra support for the catheter and preserve the curvature of the catheter while passing through tortuous vessels.Some catheters have a thin hydrophilic surface coating. When immersed in water this coating swells to a smooth, slippery film making the catheter safer and more comfortable to insert. Since this wire is too slippery to handle,  torque devices are used to control the direction and spin the wire. It is useful in subintimal angioplasty. However, care should be taken as it can easily cause dissection of vascular wall. Interventional procedures
Diagnostic catheters
There are various catheters used in angiography procedures. Diagnostic catheters direct wires through blood vessels. Radiocontrast agent is then injected through the catheter to visualise the vessels via various imaging methods such as computed tomography (CT), projectional radiography, and fluoroscopy. Pigtail catheter is a non-selective catheter with multiple side holes that can deliver large volumes of contrast into a blood vessel for imaging purposes. Cobra catheter is a selective catheter used to catheterise downgoing vessels in the abdomen. Cobra catheters move forward by pushing and are removed by pulling.