When a flow-directed balloon-tipped catheter passes from the right ventricle into the pulmonary artery and wedges, which pressure is obtained?

When a flow-directed balloon-tipped catheter passes from the right ventricle into the pulmonary artery and wedges, which pressure is obtained?

• A. Right atrial pressure
• B. Pulmonary capillary wedge pressure
• C. Left atrial pressure
• D. Pulmonary artery pressure

Answer: (B)

When the flow-directed balloon-tipped catheter is wedged in a small branch of the pulmonary artery, the distal pressure becomes equal to the pressure transmitted back from the left side of the heart through the pulmonary capillary bed. This value is the pulmonary capillary wedge pressure, which closely reflects left atrial pressure (and, by extension, left-sided filling pressures). It is used as an indirect estimate of left atrial pressure and often LV end-diastolic pressure. So, wedging yields the pressure of the left heart through the capillary network, not the right atrium or the main pulmonary artery. The right atrial pressure would be measured by other ports, and the pulmonary artery pressure is the systolic/diastolic pressure in the artery before wedging.

When the flow-directed balloon-tipped catheter is wedged in a small branch of the pulmonary artery, the distal pressure becomes equal to the pressure transmitted back from the left side of the heart through the pulmonary capillary bed. This value is the pulmonary capillary wedge pressure, which closely reflects left atrial pressure (and, by extension, left-sided filling pressures). It is used as an indirect estimate of left atrial pressure and often LV end-diastolic pressure.

So, wedging yields the pressure of the left heart through the capillary network, not the right atrium or the main pulmonary artery. The right atrial pressure would be measured by other ports, and the pulmonary artery pressure is the systolic/diastolic pressure in the artery before wedging.