Exercise-Induced Systemic Venous Hypertension in the Fontan Circulation

Abstract

Increasingly end-organ injury is being demonstrated late after institution of the Fontan circulation, particularly liver fibrosis and cirrhosis. The exact mechanisms for these late phenomena remain largely elusive. Hypothesizing that exercise induces precipitous systemic venous hypertension and insufficient cardiac output for the exercise demand, i.e. a possible mechanism for end-organ injury, we sought to demonstrate the dynamic exercise responses in systemic venous (SVP) and concurrent end organ perfusion. Ten stable Fontan patients and 9 control subjects underwent incremental cycle ergometry based cardiopulmonary exercise testing. SVP was monitored in the right upper limb and regional tissue oxygen saturation was monitored in the brain and kidney using Near Infrared Spectroscopy. SVP rose profoundly in concert with workload in the Fontan group, described by the regression equation 15.97+0.073 Watts per mm Hg. In contrast SVP did not change in healthy controls. Regional renal (p<0.01) and cerebral tissue saturations (p<0.001) were significantly lower and fell more rapidly in Fontan patients. We conclude that in a stable group of adult patients with Fontan circulation high intensity exercise was associated with systemic venous hypertension and reduced systemic oxygen delivery. This physiologic substrate has the potential to contribute to endorgan injury.

Prediction of hemodynamics under left ventricular assist device

“…Fontan circulation is an extreme case of RV failure in which RV is interpreted to be totally nonfunc-tioning. Patients with Fontan circulation have poor exercise tolerance associated with elevated central venous pressure (4,5,14). However, this is probably not due to increased total flow in Fontan circulation.…”

Cardiovascular adaptation to the Fontan circulation

“…It is intuitive that these adaptive venous mechanisms are vulnerable to hemodynamic compromise including pathway obstruction, the presence of noncompliant prosthetic materials (eg, patches, stents, and conduits) and altered PVR. Exertion results in a profound elevation in central venous pressures (often a two‐ to threefold increase) and an inadequate augmentation of cardiac output . Not surprisingly, the prevalence of chronic venous insufficiency is very high …”

“…Exertion results in a profound elevation in central venous pressures (often a two-to threefold increase) and an inadequate augmentation of cardiac output. 72 Not surprisingly, the prevalence of chronic venous insufficiency is very high. 73…”

Transcatheter Revision of Fontan Circulation by Connecting the Classical Glenn Circulation With the Inferior Vena Cava and Pulmonary Artery Circulation

“…Transcatheter Fontan completion was performed without preconditioning in this patient due to functional decline associated with chronic cyanosis, to avoid re-do sternotomy and CPB and multi-organ complications associated with Fontan failure and tan failure, and FALD is increased in patients with elevated Fontan pressures, which are known to increase further with activity [8]. As a result these patients may require multiple surgical or transcatheter interventions to address these late-onset complications.…”