Right heart catheterization (RHC) is an invasive diagnostic procedure used to assess the heart’s pumping function and measure blood flow and pressures within the heart and lungs. This procedure provides detailed, real-time information about cardiovascular performance that non-invasive tests cannot capture. RHC is also widely known as Swan-Ganz catheterization, named after its inventors. It remains an important tool for understanding heart and lung function in complex medical situations.
Defining Right Heart Catheterization
RHC involves inserting a specialized, flexible tube, known as a pulmonary artery catheter, into a large vein. This catheter is characterized by a small, inflatable balloon at its tip. The procedure is often referred to as pulmonary artery catheterization because the catheter is ultimately guided into the main artery leading to the lungs.
The catheter is typically inserted through a vein in the neck, groin, or arm. Once in the venous system, the balloon is inflated, allowing the flow of blood to gently carry the catheter through the right atrium and right ventricle, and finally into the pulmonary artery. This design made the procedure safer and simpler to perform. The catheter’s ability to measure pressures in various parts of the right side of the heart as it advances is fundamental to the procedure.
Clinical Indications for the Procedure
The information gathered from RHC is used to answer specific questions about a patient’s cardiopulmonary status. A primary indication is the diagnosis of pulmonary hypertension (high blood pressure in the arteries of the lungs). RHC is considered the definitive method for accurately measuring these pressures and confirming the diagnosis.
The procedure is also used to evaluate the severity and cause of heart failure, especially when the diagnosis is unclear or resistant to standard treatment. By directly measuring pressures, doctors determine if the heart failure affects the right side, the left side, or both. RHC also plays a role in managing complex forms of shock, such as cardiogenic shock, by helping to determine the precise volume status and the most appropriate medication strategy.
RHC is an integral part of the evaluation process for patients considered for heart transplantation. Measuring pulmonary pressures beforehand ensures the new heart will be able to pump effectively against the existing resistance in the lungs. The procedure may also be performed after a transplant to monitor how well the new organ is functioning and to check for signs of rejection.
The Procedure Steps and Patient Experience
Preparation for RHC involves fasting for several hours before the procedure. Patients lie on a padded table in a specialized procedure room, such as a cardiac catheterization laboratory. Electrodes are placed on the chest to continuously monitor the heart’s electrical activity throughout the test.
A mild sedative is often given to help the patient relax, though they remain awake during the entire procedure. The insertion site, commonly the neck or groin area, is cleaned and numbed with a local anesthetic injection. Patients may feel a brief sting or burning sensation when the numbing medication is administered.
A thin introducer sheath is placed into the vein, and the pulmonary artery catheter is threaded through it. The doctor uses pressure monitoring screens and X-ray imaging (fluoroscopy) to guide the catheter safely through the heart chambers and into the pulmonary artery. Patients typically feel pressure, but not sharp pain, as the catheter moves, and some may experience a brief feeling of a skipped heartbeat or flutter.
The RHC procedure usually takes less than an hour to complete. After the catheter is removed, pressure is applied to the insertion site to stop bleeding, and a dressing is placed. Patients are monitored in a recovery area for a few hours and are often discharged the same day, though they are advised not to drive for 24 hours due to the sedative effects.
Interpreting the Hemodynamic Results
The purpose of RHC is to collect precise hemodynamic data, which measures blood flow and pressure within the circulatory system. One core measurement is the Central Venous Pressure (CVP), the pressure in the right atrium. CVP indicates the blood volume returning to the heart, and an elevated CVP suggests fluid overload or right heart failure.
The procedure also measures the Pulmonary Artery Pressure (PAP), detailing the systolic (peak) and diastolic (lowest) pressures in the artery carrying blood from the right heart to the lungs. These values calculate the mean PAP, the defining metric for diagnosing pulmonary hypertension. Historically, a mean PAP greater than 25 mmHg has been used to confirm this diagnosis.
Another measurement is the Pulmonary Capillary Wedge Pressure (PCWP), an accurate estimate of the pressure in the left atrium and the filling pressure of the left ventricle. PCWP is obtained when the catheter balloon is inflated, temporarily “wedging” it into a small branch of the pulmonary artery. This value helps determine if high pulmonary pressures are caused by problems in the left side of the heart.
Finally, RHC calculates the Cardiac Output (CO), the total volume of blood the heart pumps per minute. CO is often determined using thermodilution, which involves injecting cool fluid into the catheter and measuring the change in blood temperature. Combining CO with pressure measurements allows doctors to calculate the Pulmonary Vascular Resistance (PVR), a measure of the resistance blood encounters flowing through the lung arteries.