title: Relationship of single ventricle filling and preload to total cavopulmonary connection hemodynamics.
abstract: BACKGROUND
  Single ventricle lesions are associated with gradual attrition after surgical palliation with the total cavopulmonary connection (TCPC). Ventricular dysfunction is frequently noted, particularly impaired diastolic performance. This study seeks to relate TCPC hemodynamic energy losses to single ventricle volumes and filling characteristics.
  
  
  METHODS
  Cardiac magnetic resonance (CMR) data were retrospectively analyzed for 30 single ventricle patients at an average age of 12.7 ± 4.8 years. Cine ventricular short-axis scans were semiautomatically segmented for all cardiac phases. Ventricular volumes, ejection fraction, peak filling rate, peak ejection rate, and time to peak filling were calculated. Corresponding patient-specific TCPC geometry was acquired from a stack of transverse CMR images; relevant flow rates were segmented from through-plane phase contrast CMR data at TCPC inlets and outlets. The TCPC indexed power loss was calculated from computational fluid dynamics simulations using a validated custom solver. Time-averaged flow conditions and rigid vessel walls were assumed in all cases. Pearson correlations were used to detect relationships between variables, with p less than 0.05 considered significant.
  
  
  RESULTS
  Ventricular end-diastolic (R = -0.48) and stroke volumes (R = -0.37) had significant negative correlations with the natural logarithm of a flow-independent measure of power loss. This power loss measure also had a significant positive relationship to time to peak filling rate (normalized to cycle time; R = 0.67).
  
  
  CONCLUSIONS
  Flow-independent TCPC power loss is inversely related with ventricular end-diastolic and stroke volumes. Elevated power losses may contribute to impaired diastolic filling and limited preload reserve in single ventricle patients.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Haggerty
authors.affiliation: Division of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Whitehead
authors.affiliation: Westat, Inc, Rockville, Maryland.
authors.forename: James
authors.initials: J
authors.lastname: Bethel
authors.affiliation: Division of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Fogel
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia. Electronic address: ajit.yoganathan@bme.gatech.edu.
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
mesh_terms: D002648:Child; D005260:Female; D018729:Fontan Procedure; D006352:Heart Ventricles / Q000002:abnormalities* / Q000503:physiopathology / Q000601:surgery*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013318:Stroke Volume; D018754:Ventricular Dysfunction / Q000503:physiopathology*