A balloon catheter is a medical device featuring a flexible tube with a small, inflatable balloon at its tip. It is used in minimally invasive procedures to gently expand or create space within bodily structures. Its ability to inflate and deflate precisely allows medical professionals to navigate complex anatomical pathways and achieve specific therapeutic outcomes without extensive open surgery.
Fundamental Design and Operation
A balloon catheter consists of a catheter shaft, a guidewire lumen, an inflation lumen, and the balloon itself, usually made from materials like nylon or polyurethane. The catheter shaft provides the main body of the device, allowing it to be maneuvered through the body’s vessels or lumens. A guidewire lumen runs through the catheter, enabling doctors to thread the catheter over a guidewire, which acts as a rail to guide the device to the target area.
The balloon, located at the catheter’s tip, is designed to inflate to a predetermined size and shape. This inflation is achieved by injecting a sterile liquid, such as saline solution or a contrast solution, through the inflation lumen. Precise control over the balloon’s size and the pressure exerted during inflation is maintained using specialized inflation devices. After the procedure, the liquid is withdrawn, causing the balloon to deflate, allowing for easy removal of the catheter.
The materials used for the balloon are chosen based on the procedure’s requirements. Some are designed to be semi-compliant or non-compliant, meaning they expand to a specific diameter regardless of pressure, offering predictable expansion.
How It Works in Angioplasty
In coronary angioplasty, a common procedure for blocked heart arteries, a balloon catheter widens narrowed vessels. The procedure begins with inserting the catheter, often through an artery in the groin or arm. It is guided by X-ray imaging to the blockage in the coronary artery. Once positioned, the deflated balloon is inflated.
Inflating the balloon presses accumulated plaque against the artery walls, widening the artery and improving blood flow to the heart. This action alleviates symptoms like chest pain and reduces the risk of serious complications, such as a heart attack. The balloon may be inflated and deflated multiple times to achieve the desired widening.
After the artery is widened, the balloon is deflated and the catheter is removed. Often, a small, expandable metal mesh tube called a stent is then placed in the newly opened artery. The stent, often pre-mounted on the balloon catheter, expands as the balloon inflates, remaining in place to keep the artery open and prevent re-narrowing. Many modern stents are drug-eluting, coated with medication that slowly releases to inhibit scar tissue growth and maintain patency.
How It Works in Other Medical Procedures
Beyond angioplasty, balloon catheters are used in various medical fields due to their ability to expand or hold structures in place. In urology, Foley catheters, which are a type of balloon catheter, are commonly used to drain urine from the bladder. A small balloon at the tip of the Foley catheter is inflated with sterile water once inside the bladder, which anchors the catheter securely in place, preventing it from slipping out.
Balloon catheters are also employed in gastroenterology for esophageal and gastrointestinal dilation. When a patient experiences a narrowed passage, such as an esophageal stricture, a balloon catheter is guided to the site and inflated to stretch the constricted area, improving the passage of food and liquids. This helps relieve swallowing difficulties and discomfort.
Some advanced balloon catheters, known as drug-eluting balloons, deliver medication directly to a specific site within the body. These balloons rapidly transfer medication to the vessel wall upon inflation, used for conditions like restenosis in arteries. Additionally, balloon catheters can be used for temporary vascular occlusion, where the inflated balloon temporarily blocks blood flow in a vessel for surgical or interventional purposes.