In left heart failure, how are the Pulmonary Artery Pressure (PAP) and Pulmonary Capillary Wedge Pressure (PCWP) affected?

In left heart failure, the dynamics of blood flow and pressure within the heart and pulmonary circulation are significantly altered. When the left ventricle fails to effectively pump blood out to the systemic circulation, blood can back up into the pulmonary circulation. This congestion leads to an increase in both the Pulmonary Artery Pressure (PAP) and the Pulmonary Capillary Wedge Pressure (PCWP).

The PAP reflects the pressure within the pulmonary arteries and normally ranges from 8 to 20 mmHg. In left heart failure, as the left ventricle struggles to eject blood, the pressure within the lungs rises because of the backlog, resulting in elevated PAP levels.

PCWP, which is a measure of the pressure in the left atrium and reflects left-sided heart pressures more accurately, also rises due to the increased fluid accumulation and pressure from the left heart. Normal PCWP values should be around 6 to 12 mmHg; however, it can increase significantly in left heart failure, often exceeding 18 mmHg, indicating congestion in the pulmonary capillaries.

Thus, in left heart failure, both PAP and PCWP are increased, leading to pulmonary congestion and possible manifestations of pulmonary edema due to the elevated pressures. This is why the