What does the wedge pressure of a pulmonary catheter measure?

The wedge pressure measured by a pulmonary catheter refers to the left atrial pressure. This measurement is obtained by inflating a balloon at the catheter tip, occluding a pulmonary artery branch, and allowing it to equilibrate with the blood pressure in the left atrium.

A characteristic of this measurement is its relevance to assessing left ventricular function and diagnosing conditions like heart failure. When there is elevated wedge pressure, it indicates a back pressure resulting from increased left atrial pressure, commonly due to issues such as fluid overload or diastolic dysfunction of the left ventricle.

While left end-diastolic pressure and left atrial pressure are closely related, the direct measurement obtained through the pulmonary catheter is specifically indicative of left atrial pressure indirectly, as it serves as a reflection of what the left atrium is experiencing at that moment.