title: Pneumatically-driven external pressure applicator to augment Fontan hemodynamics: preliminary findings.
abstract: BACKGROUND
  This study investigated the application of circumferentially applied, external pressure to the lower extremities as a preventative measure and long-term clinical treatment strategy for Fontan patients.
  
  
  OBJECTIVE
  We hypothesized that the application of circumferential pressure to the lower limbs will augment venous return and thus cardiac output.
  
  
  METHODS
  Two patients (an extra-cardiac and intra-atrial Fontan) were evaluated. Both trials were conducted during a routine cardiac catheterization. The aortic and inferior vena cava (IVC) pressures were recorded. We applied three different external pressures to the lower limbs based on the patient's diastolic pressure. Each pressure was applied with a one-minute rapid inflate/deflate period for a total of five cycles and a rest period between pressure intervals.
  
  
  RESULTS
  Patient 1 (age 37, female) demonstrated pressure rises of 10-15 mmHg in both the aortic and IVC pressures. Patient 2 (age 24, male) had undetectable pressure rise during the first pressure cycles and notable pressures rise of approximately 8-12 mmHg during the third cycle.
  
  
  CONCLUSIONS
  External pressure application redistributes blood volume or cardiac output as a result of impedance in the lower extremities, enhancing venous pressure and return. Our findings strongly suggest an acute benefit from the implementation of external mechanical compression of the lower vasculature to increase cardiac output in Fontan patients.
authors.affiliation: BioCirc Research Laboratory, School of Biomedical Engineering, Science and Health Systems, Drexel University, USA ;
authors.forename: Amy L
authors.initials: AL
authors.lastname: Throckmorton
authors.affiliation: Department of Mechanical and Nuclear Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA, USA ;
authors.forename: Sonya S
authors.initials: SS
authors.lastname: Bhavsar
authors.affiliation: Department of Mechanical and Nuclear Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA, USA ;
authors.forename: Steven G
authors.initials: SG
authors.lastname: Chopski
authors.affiliation: Division of Pediatric Cardiology, Children's Hospital of Richmond and School of Medicine, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: William B
authors.initials: WB
authors.lastname: Moskowitz
keywords: Fontan; blood pump; counterpulsation; single ventricule physiology; total cavopulmonary connection
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