A cardiac catheterization is a minimally invasive procedure performed inside a specialized hospital setting known as the cardiac catheterization laboratory, or “cath lab.” This environment is equipped with advanced diagnostic imaging technology, allowing specialists to visualize the heart’s arteries and chambers in real-time. The procedure uses slender, flexible tubes called catheters, which are guided through the blood vessels to the heart to gather data or perform treatments.
Why Cardiac Catheterization Is Performed
The purposes of a cardiac catheterization fall into two main categories: diagnostic and interventional. A diagnostic procedure is performed to gather information about the structure and function of the heart. For example, coronary angiography involves injecting a contrast dye to map the coronary arteries, identifying the location and severity of any blockages.
Diagnostic catheterization also allows physicians to measure pressures within the heart chambers and major blood vessels, which is helpful in assessing heart valve function or diagnosing pulmonary hypertension. The procedure can also be used to collect blood samples to determine oxygen levels or to perform a biopsy by taking a small tissue sample.
When a problem is identified, the physician may immediately transition to an interventional, or treatment, procedure. These therapeutic interventions include opening narrowed arteries through percutaneous coronary intervention (PCI), often involving balloon angioplasty and the placement of a stent to keep the vessel open. Catheterization can also be used to repair structural heart defects, such as certain valve issues or congenital holes in the heart.
Preparing for the Catheterization Procedure
Preparation for a cardiac catheterization typically begins with a review of the patient’s medical history and current medications. Patients are instructed not to eat or drink anything for six to eight hours before the procedure to prevent complications from sedation. Specific instructions are provided regarding regular medications, as blood thinners like warfarin or certain diabetes medications may need to be temporarily stopped or adjusted beforehand.
Pre-procedure testing commonly involves blood work, including kidney function tests, and an electrocardiogram (ECG) to assess the heart’s electrical activity. The care team ensures the patient and family understand the procedure, its risks, and its benefits, completing the informed consent process. On the day of the procedure, a nurse will start an intravenous (IV) line to administer fluids and medication to help the patient relax.
The Step-by-Step Procedure Inside the Cath Lab
Once inside the cath lab, the patient is positioned on a procedure table and connected to monitoring equipment, including an ECG machine and blood pressure cuff, for continuous observation of vital signs. A sedative is usually administered through the IV line to ensure comfort, though the patient remains awake and able to follow instructions throughout the procedure. The physician then cleans and prepares the chosen access site, which is most often the radial artery in the wrist or the femoral artery in the groin.
The access site is numbed with a local anesthetic injection, making the initial incision the only part of the procedure where the patient may feel a sharp sensation. A small puncture is made, and a short, hollow plastic tube called a sheath is inserted into the artery, providing a secure port for the physician to work through. A thin, flexible guidewire is then threaded through the sheath and into the blood vessel.
The catheter, a long, narrow tube, is advanced over the guidewire and carefully maneuvered through the arterial network toward the heart. The physician uses an X-ray technique called fluoroscopy, which generates a real-time image of the internal structures, to guide the catheter’s tip. Because the inner walls of blood vessels do not have pain receptors, the patient does not feel the catheter moving through the body.
To visualize the coronary arteries or heart chambers, a radiopaque contrast dye is injected through the catheter. This dye highlights the blood vessels on the fluoroscopy screen, creating an angiogram that reveals any areas of narrowing or blockage. Patients may feel a temporary warm or flushed sensation as the contrast material circulates through the bloodstream. If a block is found, the physician may proceed directly to an intervention like angioplasty, using a balloon-tipped catheter to widen the artery and often placing a stent to support the vessel wall.
Immediate Recovery and Post-Procedure Care
After the diagnostic or interventional phase is complete, the catheter and the introducer sheath are removed from the access site. Controlling bleeding at this puncture point is a primary focus of post-procedure care. If the femoral artery in the groin was used, bleeding is stopped either by applying firm manual pressure or by deploying a specialized closure device.
The patient is then moved to a recovery area for continuous monitoring of the heart rhythm, blood pressure, and the access site. If the groin was used, the patient must lie flat for several hours, typically between two and six, to allow the artery to seal completely. Access through the radial artery often requires less downtime and allows the patient to sit up sooner.
Before discharge, patients are encouraged to drink plenty of fluids to help flush the contrast dye from their system. Instructions for home recovery include specific activity restrictions:
- Avoiding heavy lifting for several days.
- Refraining from submerging the puncture site (e.g., bathing or swimming) for about one week.
- Monitoring the access site for signs of excessive bleeding.
- Monitoring the access site for swelling or infection.