been chewing on this for a couple weeks. Systrom’s group at Brigham does invasive CPET, catheters in the pulmonary artery and radial artery during exercise, actual pressure readings while you’re on the bike. not just breath analysis like the Workwell two-day protocol I posted about before. this measures what the heart is doing in real time.
what he keeps finding in ME/CFS and long covid patients is a preload failure pattern. right atrial pressure stays low during exercise when it should climb. the heart isn’t filling with enough blood coming back from the periphery, so stroke volume tanks and the body compensates by cranking heart rate. that’s the tachycardia so many of us get standing up or two minutes into a light walk.
it’s not deconditioning and it’s not the heart itself failing, it’s the return circuit. as a PT this landed different than the CPET data did. I’ve spent 20 years thinking about return of function in terms of muscle and joint mechanics. reading this, I kept thinking about my own tilt table result, HR spiking with no BP drop, and realizing that’s probably the same preload story playing out standing instead of pedaling.
the catch is almost nobody gets access to iCPET. it’s invasive, it’s a handful of centers, insurance fights it. so we’re left with a mechanism that explains a lot and almost no path to actually getting tested for it. anyone here actually gotten iCPET done, and did it change how your doctor treated the POTS piece?