On a pulmonary artery waveform, the dicrotic notch represents the closure of which valve?

The dicrotic notch on a pulmonary artery waveform is indicative of the closure of the pulmonic valve. This notch is formed during the cardiac cycle when the valve closes after ventricular systole, marking the end of the ejection of blood from the right ventricle into the pulmonary artery. The closure of the pulmonic valve corresponds with a momentary backflow of blood that causes a brief increase in the pressure waveform, resulting in the characteristic notch seen in the tracing.

Understanding this concept is crucial for interpreting hemodynamic data from patients, especially those with pulmonary or cardiac issues, as it provides valuable information regarding right heart function and pressures within the pulmonary circulation. The presence of the dicrotic notch is thus a key feature that clinicians look for when evaluating pulmonary arterial waveforms.