Right heart catheterization

Overview
Synonyms include: Pulmonary artery catheterization, wedge, PA line, Swan Ganz catheterization, right heart cath.

Pulmonary artery catheterization is the insertion of a catheter into a pulmonary artery. Its purpose is diagnostic; it is used to detect heart failure or sepsis, monitor therapy, and evaluate the effects of drugs. The pulmonary artery catheter allows direct, simultaneous measurement of pressures in the right atrium, right ventricle, pulmonary artery, and the filling pressure ("wedge" pressure) of the left atrium.

The pulmonary artery catheter is frequently referred to as a Swan-Ganz catheter, in honor of its inventors Jeremy Swan and William Ganz, from Cedars-Sinai Medical Center. The idea for this catheter (as later revealed by Dr. Swan) came about from the observation of sailboats on the water.

Indications
General indications are
 * Management of complicated myocardial infarction:
 * To differentiate hypovolemia vs cardiogenic shock
 * To differentiate ventricular septal defect (VSD) vs acute mitral regurgitation
 * To tailor therapy in severe left ventricular failure
 * To manage volume administration in right ventricular infarction


 * Assessment of respiratory distress
 * To differentiate cardiogenic vs non-cardiogenic pulmonary edema
 * To differentiate primary vs secondary pulmonary hypertension


 * Assessment of type of shock


 * Assessment of response to therapy
 * Afterload reduction
 * Vasopressors
 * Beta blockers
 * Intra-aortic balloon counterpulsation


 * Assessment of fluid requirement in critically ill patients with:
 * Hemorrhage
 * Sepsis
 * Acute renal failure
 * Burns


 * Management of postoperative open heart surgical patients


 * Assessment of valvular heart disease


 * Assessment of cardiac tamponade / constriction

Procedure
The catheter is introduced through a large vein&mdash;often the internal jugular, subclavian, or femoral veins. From this entry site, it is threaded, often with the aid of fluoroscopy, through the right atrium of the heart, the right ventricle, and subsequently into the pulmonary artery.

The standard pulmonary artery catheter is equipped with an inflatable balloon at the tip, which facilitates its placement into the pulmonary artery through the flow of blood. The balloon, when inflated, causes the catheter to "wedge" in a small pulmonary blood vessel. So wedged, the catheter can provide a measurement of the pressure in the left atrium of the heart.

Complications
The procedure is not without risk, and complications can be life threatening. It can lead to arrhythmias, rupture of the pulmonary artery, thrombosis, infection, pneumothorax, bleeding, and other problems.

Controversy
The benefit of the use of this type of catheter has been controversial. Therefore many clinicians minimize its use.

Evidence of benefit
Several studies in the 1980s seemed to show a benefit of the increase in physiological information. Many reports showing benefit of the PA catheter are from anesthestic and surgical settings. In these settings cardiovascular performance was optimized thinking patients would have supranormal metabolic requirements.

Evidence of harm or lack of benefit
Contrary to earlier studies there is growing evidence the use of a PA catheter (PAC) does not necessarily lead to improved outcome. For example, see. The following explanations have been advanced. One explanation could be that nurses and physicians were insufficiently knowledgeable to adequately interpret the PA catheter measurements. Also, the benefits might be reduced by the complications from the use of the PAC. Furthermore, using information from the PAC might result in a more aggressive therapy causing the detrimental effect. Or, it could give rise to more harmful therapies (i.e. achieving supranormal values could be associated with increased mortality).

Additional resources

 * Intensive Care Medicine by Irwin and Rippe
 * The ICU Book by Marino
 * Procedures and Techniques in Intensive Care Medicine by Irwin and Rippe