The catheter is not the Hollywood starlet of medical devices. Hardly glamorous, it’s a tube that goes inside the body. Despite their diminutive size and seemingly basic function, however, catheters have become an integral part of the modern healthcare system and are driving innovation in the industry.
Navigating the human circulatory system can be a difficult endeavor, but modern technology has brought us from reeds and metal-jointed tubes to space-age polymers and microscopic sizes that can perform a plethora of tasks and tap the inner reaches of our bodies without painful, invasive open surgeries.
Catheters are a central piece in modern hospitals and healthcare facilities, treating life-threatening lesions, scraping calcified plaque off arteries, reshaping our hearts, delivering new artificial valves and snaking into our brain to prevent fatal aneurysms.
The most basic and recognizable is the Foley catheter, designed to serve a basic function in the urinary tract. But it’s rather advanced compared to its ancestor, a tube made from jointed metal segments hinged together with wire developed by Benjamin Franklin in the 18th century.
Franklin credited the invention to Francesco Roncelli-Pardino, but the idea of using straw-like devices to create pathways into the human body can be traced back thousands of years. Materials then were less than ideal – reeds, palm leaves and straw.
New materials introduced in the mid-19th and early 20th centuries, in the form of rubbers and plastics, revolutionized the devices. In the 1930s, Boston-based surgeon Dr. Frederick Foley devised the catheter we still see in use today. Foley, recognizing that urinary catheters had a tendency to slip out of bodies during use, designed a catheter with a small balloon on the end to hold it in place.
But catheters do more than just treat urinary issues. Catheters were pivotal in the development and deployment of the 1st coronary stents and scaffolds – now a standard of care for percutaneous coronary interventions. The first coronary stent was deployed in 1986; 13 years later, stenting made up 84.2% of all PCIs.
Catheter-based stenting has come a long way since its initial, bare-metal introduction. In the early 2000s, drug-eluting stents were introduced to minimize restenosis and the reinterventions associated with early bare-metal stents. Unlike their simpler ancestors, the polymer-coated drug-eluting devices contained antiproliferative agents to prevent neointimal hyperplasia, reducing restenosis rates significantly.
Development of new materials, which could be absorbed into the body after use, has lead to the development of bioabsorbable stents. Over the last decade, major players in medical devices including Abbott, Boston Scientific, Biotronik and Reva Medical have invested heavily in developing bioabsorbable stents.
In the U.S., bioabsorbable stents have yet to cross the finish line with the FDA. The closest product to win approval here is Boston Scientific’s polymer-coated, bioresorbable Synergy device, which features a polymer coating that’s designed to dissolve after delivering its drug payload, leaving a bare-metal scaffold behind.
Abbott is on track to win clearance for its fully absorbable Absorb stent, which has already been approved in the European Union. Absorb is made out of a poly-l-lactide acid biopolymer with an everolimus coating and is designed to be entirely reabsorbed over a matter of months after it’s deployed with an advanced catheter-based delivery system.
Beyond deploying stents, catheters are the driving force in a number of newly developed procedures to repair the peripheral vasculature. Diamond-tipped, pneumatically driven catheters are at the heart of orbital atherectomy, a new procedure designed to treat peripheral artery disease. PAD is a narrowing or blockage of vessels that carry blood from the heart and lungs to the arms and legs, primarily due to the buildup of fatty plaque in the arteries. Approximately 8 million people in the U.S. have the disease, according to the Centers for Disease Control & Prevention, affecting between 12% and 20% of all individuals older than 60.
In orbital atherectomy procedures, which are being spearheaded by St. Paul, Minn.-based Cardiovascular Systems and its Diamondback series of devices, a catheter tipped with a diamond-coated crown and powered by a pneumatic drive console is used to physically debulk and remove the plaque from within diseased arterial segments. The system uses a larger guidewire than earlier rotational atherectomy procedures to advance more easily through tight stenoses while allowing continuous blood flow through the vessels.
Catheters have also been at the center of other heart treatments for more than 30 years. The first catheter ablation to correct atrial fibrillation occurred in 1981. The early procedure used high-energy DC electricity to cauterize the muscle of the heart, disrupting dangerous arrhythmias. Ablation has come a long way since then, with energy sources varying from lasers to cryogenic freezing, and newer devices are being designed to allow surgeons to see the tissue they’re ablating.
Cardiofocus, based in Marlborough, Mass., has developed a visually guided laser balloon designed for ablation procedures for treating paroxysmal atrial fibrillation. The system incorporates an endoscope to provide physicians with the ability to see within the heart, for the first time ever, and visually direct the application of laser energy to achieve durable pulmonary vein isolation. The device is already approved in the European Union and the company is on track for FDA approval after submitting an application with the agency last fall.
In addition to shaping the heart, catheters are helping surgeons add to it with micro-sized valve replacements. Through the use of catheters, surgeons are able to guide expanding replacement valves into place in patients too sick to undergo open surgery. Transcatheter aortic valve repairs have been around for nearly 20 years, but new developments are pushing the envelope with replacements designed for the mitral, pulmonary and even tricuspid valves.
Mitral valve regurgitation is a much more common problem that aortic stenosis, affecting nearly 10% of all people age 75 or older, meaning the potential market for TMVR could be two or three times larger than its older TAVR cousin. But the mitral valve’s anatomy is much more complex than the aortic valve’s, making TMVR devices and their delivery systems much more difficult to design.
The FDA cleared the first transcatheter mitral repair product, Abbot’s MitraClip, in 2013, though the device is not designed to replace worn-out or heavily stenosed valves. Many big players in medtech are tilting at TMVR, having dropped more than $2 billion combined last year to buy early developers of the tech. Medtronic paid $458 million for TMVR developer Twelve Inc., Abbott dropped $250 million on TMVR developer Tendyne and Edwards LifeSciences spent $400 million to buy CardiAQ Valve Technologies and their TMVR tech.
Innovations in catheter technology have brought the devices into every part of our body, including our brains. New catheter technology is allowing for the minimally invasive treatment of brain aneurysms – dangerous bulging or weaknesses in artery walls. Normally, procedures to correct the life-threatening problem are carried out by physically clipping the base of the aneurysm, which requires intensely invasive surgery in which the patient’s skull or brow is opened to provide access.
Medtronic recently won approval from the FDA for its catheter-based Pipeline Flex embolization device (also a former Covidien product) to treat brain aneurysms. With the Pipeline device, a catheter is snaked into the delicate vasculature of the brain, where it deploys a flexible tube from the base to the end of the embolism to guide blood flow along the vessel and away from the possibly fatal vascular expansion.
Both Boston Scientific and Cordis have developed devices to treat the same problem through the deployment of coils – microsized cords that range from smaller than a human hair to twice its width, made of soft platinum metal and shaped like a spring. A microcatheter is fed into the brain and the coil is deployed to fill the aneurysm.
Innovation is continuing with catheters – they’re connected to new developments including leadless pacemaker deployment, repairing holes in the heart with the aid of biodegradable adhesives and filtering out dangerous blood clots.
Although small in stature, catheters are driving medtech innovations that reach into every corner of the human body.