Descent into the Swan

Another day off means another post! Let’s make this a quick one on something I pretended to understand but really don’t:

Pulmonary artery catheter waveforms! Don’t you always hate it when the heart failure attending or fellow starts saying yeah the CVP isn’t the one projected in the parenthesis and then starts staring at the screen and says A-wave, V-wave, etc?

Here are the basics first as a reminder. 10–15cm to the subclavian. I like the rule of 6’s; you can use the dimes one too. Up to you. This is all derived from the manufacturer, Edwards, page.

RA: 6, RV: 26/6, PA: 24/12 (higher diastolic seen in “step-up” and going past the PV), PAWP: 12

Right Atrial/Central venous pressure Waveform

A- wave: atrial contraction

C-wave: tricuspid valve closes and “bulging” into atrium as ventricle contractions; hence the quick upsloping

X-descent: atrial relaxation

V-wave: atrial filling (ventricular contraction/systle)

Y-descent: tricuspid valve opens

The picture above is also taken from Edwards LifeSciences Swan page. I thought it was interesting because we float swans all the time but I never knew this stuff. The last image of spontaneous wedging looks similar to a normal PA waveform to me though.

Ok I’m done.

Dk