Catheters are highly useful tools in the diagnosis and treatment of heart disease. They can be used to diagnose conditions such as arrhythmias and coronary artery disease, and to treat these same conditions, as well as many others. In some cases, both diagnosis and treatment can be performed during the same catheter-based procedure. Because they cause less trauma than open heart surgery, catheter-based procedures are often referred to as minimally invasive alternatives to surgery.

During a catheter-based treatment to fix a cardiac condition, a physician inserts a small tube called a catheter into a patient’s blood vessel and passes the tube toward the heart. The catheter may be equipped with any number of special devices, such as balloons, grinding burrs, baskets, suction devices or stents. Examples of catheter-based procedures include:

• Balloon angioplasty. About 670,000 balloon angioplasties (sometimes called percutaneous coronary interventions) are performed annually in the United States, making this procedure more common than coronary artery bypass graft surgery. During a balloon angioplasty, the physician inflates a small balloon located at the tip of a catheter to crush plaque back against the artery wall, allowing for better blood flow through the artery. This procedure is usually accompanied by implantation of a stent. A stent is a small metal tube-shaped device that is implanted in the diseased portion of the artery after angioplasty. Just as scaffolding supports a weak building, stents support the damaged artery walls, reducing the chance that the vessel will close again (restenosis) after treatment. Stents called drug-eluting stents are coated with a drug that reduces the chances of restenosis. Newer studies have questioned the long-term effectiveness of drug-eluting stents, but in general, these devices are considered very safe and are used in the majority of stent procedures. 
  
  
• Atherectomy. If arterial plaque is particularly hard, the physician may choose to do an atherectomy. There are three types of atherectomy, all of which cut away plaque from a clogged artery. A stent may be implanted after an atherectomy.
  
  
• Transmyocardial revascularization (TMR). In some cases when patients suffer from severe coronary artery disease and is not a candidate for other techniques, a laser delivered by a catheter (or through a surgical incision) can be used to burn a series of small holes into the heart muscle to improve blood flow to relieve the pain of angina.
  
  
• Percutaneous balloon valvoplasty. A procedure in which a balloon at the end of a catheter is inflated to widen abnormally narrowed heart valves in newborns or adults. This procedure may also be called valvotomy.
  
  
• Percutaneous balloon pericardiotomy. A procedure where a balloon-tipped catheter creates a tear in the wall of the pericardium, through which a drainage tube can be inserted. This is a treatment option in cardiac tamponade.
  
  
• Rashkind procedure. A procedure in which a balloon-tipped catheter is snaked through an abnormal hole in the septum (the wall between the left and right sides of the heart). The balloon is first inflated and then drawn through the hole. The purpose is to enlarge the hole in order to temporarily stabilize a child born with a major congenital heart defect, such as transposition of the great arteries. When the child is strong enough, the defect will be repaired with another type of surgery.
  
  
• Closing a congenital heart defect, such as an atrial septal defect (a hole between the upper chambers of the heart) or a patent ductus arteriosus (an open blood vessel that should normally close by itself after birth). For example, coil embolization is a relatively new technique for closing a patent ductus arteriosus (PDA). Placed inside the PDA via a catheter, the coil is held in place while the fibers encourage the formation of a blood clot, sealing the PDA closed. The coil is left in place and, over time, a scar forms that keeps the PDA permanently closed. For atrial septal defect (and ventricular septal defect), catheter-based delivery of “patches” seals off the open hole. The patch eventually becomes covered with the body’s tissue.
  
  
• Ablation. During ablation, very small, carefully selected parts of the heart are destroyed either with electrical impulses or alcohol injection. This may be used to prevent tachycardia, an abnormally fast heartbeat, or reduce the size of abnormally large heart structures (alcohol septal ablation). Special catheters are also being developed to detect and “map” arrhythmic areas of the heart (e.g., atrial fibrillation, paroxysmal atrial fibrillation).
  
  
• Insertion of a temporary pacemaker or an intra-aortic balloon pump.
  
  
• Carotid angiograms. Similar to a coronary angiogram, this procedure is performed in the carotid artery, which lies in the neck and supplies oxygen-rich blood to the brain. Using this test, physicians can detect aneurysms in the brain, which may cause a stroke if they rupture. Catheters may also be used to treat these aneurysms by implanting tiny coils in the aneurysm that cause a blood clot to form and seal off the aneurysm.
  
  
• To deliver clot-busting drugs directly into a blood clot. This is a valuable technique in the treatment of ischemic stroke, which occurs when a blood clot obstructs blood flow to the brain.
  
  
• Heart valve replacement. Studies are ongoing to develop methods to replace certain heart valves using catheters instead of traditional heart surgery. Currently, however, these methods are highly experimental and are not part of clinical practice.
  
  
• Infusion therapy to deliver vasodilator drugs in patients with severe primary pulmonary hypertension, or for heart failure.
  
  
• Percutaneous in situ coronary venous arterialization (PICVA). This procedure may be recommended in very severe cases of coronary artery disease. During this procedure, blood flow is routed from a coronary artery into one of the coronary veins, which normally drain oxygen-poor blood from the heart muscle. Studies have shown that, by doing this, physicians can force oxygen-rich blood backward through the venous system, thus providing a new supply of oxygen-rich blood for the heart muscle. This procedure uses a system of highly specialized catheters and is still under development.

Catheter-based procedures are also being used in experimental gene therapy studies to inject genetically altered substances into the heart muscle. As an example, catheters are used to inject growth factors into the myocardium to promote the growth of new blood vessels (therapeutic angiogenesis). They are also used to inject stem cells into the heart for patients with heart failure. Other innovations include:

• Catheters to advance medical devices to “seal off” areas of the heart susceptible to blood clot formation. This may be particularly useful in patients with atrial fibrillation, which is associated with an increased risk of blood clots.
  
  
• Small sensors for heart failure and aneurysm patients. These are advanced by a catheter to a blood vessel to continuously measure pressure inside an artery.
  
  
• Photoangioplasty, where a special light-sensitive drug is injected directly into the patient’s veins about 24 hours before the procedure. In the bloodstream, the drug attaches itself to areas of fatty plaque buildup. A fiber-optic laser in then threaded through the body via a catheter and into the affected areas. Once in the target area, the laser is activated and its light triggers a reaction in the drug that dissolves the plaque and spares the local tissue. Although this procedure is still considered experimental, early clinical trials have yielded encouraging results.
  
  
• Catheter-vacuum extractors. These combination catheters are sometimes used during angioplasty following a heart attack. The metal tip of the catheter destroys the blood clot, and the vacuum extractor removes it.