Externally applied compression therapy for Fontan patients

Abstract

Background: Limited therapeutic options are available for Fontan patients with dysfunctional or failing single ventricle physiology. This study describes the evaluation of an alternative, non-invasive, at-home therapeutic compression treatment for Fontan patients. Our hypothesis is that routinely administered, externally applied compression treatments to the lower extremities will augment systemic venous return, improve ventricular preload, and thus enhance cardiac output in Fontan patients.

Methods: To initially evaluate this hypothesis, we employed the NormaTec pneumatic compression device (PCD) in a pilot clinical study (n=2). This device is composed of inflatable trouser compartments that facilitate circumferentially and uniformly applied pressure to a patient's lower extremities. Following an initial health screening, test subjects were pre-evaluated with a modified-Bruce treadmill exercise stress test, and baseline data on cardiorespiratory health was collected. After training, test subjects conducted 6 days of external compression therapy at-home. Subjects were then re-evaluated with a final treadmill stress test and data acquisition of new cardiorespiratory parameters.

Results: Both subjects demonstrated improvement in exercise duration time, peak oxygen volume, and ventilator threshold, as compared to the baseline evaluation.

Conclusions: These findings are promising and provide the foundation for future studies that will focus on increasing study participation (sample size) to better assess the clinical benefit of compression therapy for Fontan patients.

Keywords: Enhanced external counterpulsation (EECP); congenital heart disease (CHD); single ventricle physiology.

Figure 1

Single ventricle Fontan physiology (2). SV, single ventricle; RPA, right pulmonary artery; LPA, left pulmonary artery; TCPC, total cavopulmonary connection; EC, extra-cardiac; IVC, inferior vena cava; SVC, superior vena cava.

Figure 2

NormaTec pneumatic compression device (PCD).

Figure 3

NormaTec PCD action. Initial compression of the feet and ankles results in an upward push of blood volume that is supported by subsequent compartment compressions from 2 to 5. PCD, pneumatic compression device.

Figure 4

Clinical study timeline of events.

Figure 5

RER (VCO₂/VO₂) vs. time (mm:ss) subject #1 (pre- and post-treatment stress test). RER, respiratory exchange rate.

Figure 6

VO₂ (mL/kg/min) vs. time (mm:ss) subject #1 (pre- and post-treatment stress test).

Figure 7

VO₂ (mL/kg/min) vs. time (mm:ss) subject #2 (pre- and post-treatment stress test).