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Editorial in #Jacc 
https://bit.ly/3mrnH3l on failing Fontan physiology with @MarcGewillig Our take on superb research by Drs. Egbe and Borlaug @MayoClinicCV 1/8
https://bit.ly/3mrnH3l on failing Fontan physiology with @MarcGewillig Our take on superb research by Drs. Egbe and Borlaug @MayoClinicCV 1/8
In Fontan patients, cardiovascular physiology is dramatically changed by putting the pulmonary vasculature as a dam between systemic venous return and the systemic ventricle. 2/8
Hence, pulmonary vasculature determines upstream congestion (and FALD for that matter) and downstream (low) flow, 2 hallmarks of Fontan failure. Flow across the dam is determined by PVR, systemic venous pressure and downstream pressure/pull. 3/8
Exercising Fontan patients is a fantastic way to improve signal-to-noise ratio since low-flow will result in larger measurement error, especially in the systemic venous circulation. 4/8
We already did exercise CMR with invasive pressure measurements to see that hemodynamics, even in well Fontan patients, differ from normals. Some of the ideas are further explored in an editorial with @ShelbyKuttyMD https://bit.ly/3fRRXSy 5/8
It's intriguing that a TPR of >3 mmHg per L/min increase in CO works equally well in Fontan patients, just as it does in patients with a biventricular circulation. I do wonder whether Fontan patients would be able to increase CVP >35 mmHg 6/8
Whether this, by definition, indicates a pulmonary vascular problem, is not so sure. The authors measured PCWP and its increase appears a bit steeper than expected. Still, we were able to lower pressure-volume plots using a dose of sildenafil. https://bit.ly/3fSFkqn 7/8
For the editorial, we plotted good Fontan patients (our data) alongside low and high TPR Fontan patients (data taken from https://bit.ly/33z2c9o ) and controls, which makes a fascinating graph. https://bit.ly/3qj6X0j 8/8
Conclusion, more studies needed, but exciting avenue to assess Fontan patients and effect of therapy..
