Pulmonary Capillary Wedge Pressure (PCWP) reflects which cardiac pressure?

Pulmonary Capillary Wedge Pressure (PCWP) reflects which cardiac pressure?

• A. Right atrial pressure
• B. Pulmonary arterial pressure
• C. Left atrial pressure
• D. Left ventricular filling pressure

Answer: (D)

Pulmonary capillary wedge pressure is a measure of pressure on the left side of the heart that reflects the preload of the left ventricle. When the catheter is wedged in a small pulmonary artery branch, the pressure distal to the balloon equilibrates with the pressure in the pulmonary capillaries and, via the pulmonary veins, with the left atrial pressure. Because the left atrial pressure is governed by the filling (preload) of the left ventricle, PCWP serves as an indirect estimate of left-sided filling pressure, i.e., the left ventricular end-diastolic pressure. In other words, it tells you about how much pressure the left ventricle is filling against during diastole. This is why elevated PCWP points to cardiogenic causes of pulmonary edema and helps distinguish left-sided preload from right-sided pressures. If the mitral valve is diseased, or there are significant left atrial–pulmonary venous abnormalities, the correlation can be less exact, but the general principle remains that PCWP reflects left-sided filling pressures rather than right atrial or pure pulmonary arterial pressures.

Pulmonary capillary wedge pressure is a measure of pressure on the left side of the heart that reflects the preload of the left ventricle. When the catheter is wedged in a small pulmonary artery branch, the pressure distal to the balloon equilibrates with the pressure in the pulmonary capillaries and, via the pulmonary veins, with the left atrial pressure. Because the left atrial pressure is governed by the filling (preload) of the left ventricle, PCWP serves as an indirect estimate of left-sided filling pressure, i.e., the left ventricular end-diastolic pressure. In other words, it tells you about how much pressure the left ventricle is filling against during diastole. This is why elevated PCWP points to cardiogenic causes of pulmonary edema and helps distinguish left-sided preload from right-sided pressures. If the mitral valve is diseased, or there are significant left atrial–pulmonary venous abnormalities, the correlation can be less exact, but the general principle remains that PCWP reflects left-sided filling pressures rather than right atrial or pure pulmonary arterial pressures.