title: Novel insights into RV adaptation and function in hypoplastic left heart syndrome between the first 2 stages of surgical palliation.
abstract: OBJECTIVE
  This study sought to examine the changes in ventricular function of hypoplastic left heart syndrome (HLHS) between the first 2 stages of surgical palliation.
  
  
  BACKGROUND
  The mortality risk between first and second stages of surgical palliation in HLHS remains high. Right ventricular (RV) dysfunction predicts mortality. Postulated mechanisms include a maladaptive contraction pattern, myocardial ischemia, or contraction asynchrony. Speckle tracking imaging allows accurate measurement of myocardial deformation without geometric assumptions.
  
  
  METHODS
  Prospective echocardiography pre-Norwood and pre-bidirectional cavopulmonary anastomosis (BCPA) examinations were performed in 20 HLHS patients, with comparisons made between stages. Measurements of ventricular function included: longitudinal/circumferential strain ratio, reflecting changes in contraction pattern; post-systolic strain index, a potential marker of myocardial ischemia; and mechanical dyssynchrony index. Relationships between echocardiographic variables and magnetic resonance imaging RV parameters before BCPA were examined.
  
  
  RESULTS
  Before BCPA, myocardial contractility estimated by isovolumic acceleration and strain rate was reduced, paralleled by an increased in post-systolic strain index (p < 0.01). Right ventricular longitudinal/circumferential strain ratio decreased, becoming similar to a left ventricle-like contraction pattern, and this correlated with decreased mechanical dyssynchrony index (r = 0.65, p < 0.01), magnetic resonance imaging RV end-diastolic volume (r = 0.65, p < 0.05) and mass (r = 0.71, p < 0.01). Ventricular strain (r = -0.72, p < 0.01), strain rate (r = -0.85, p < 0.001), and mechanical dyssynchrony index (r = -0.73, p < 0.01) correlated linearly with magnetic resonance imaging-derived RV ejection fraction.
  
  
  CONCLUSIONS
  Reduced RV contractility occurred before BCPA. RV with a left ventricle-like contraction pattern was associated with improved contraction synchrony as well as a reduction in RV size and mass in HLHS. The finding of increased post-systolic strain index before BCPA is novel and its potential link with myocardial ischemia warrants further investigation. RV strain, strain rate, and contraction synchrony measured by speckle tracking imaging correlated closely with ventricular function and might be useful for monitoring ventricular function in HLHS.
authors.affiliation: University of Alberta, Stollery Children's Hospital, Edmonton, Alberta, Canada. khoo@ualberta.ca
authors.forename: Nee Scze
authors.initials: NS
authors.lastname: Khoo
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Smallhorn
authors.forename: Sachie
authors.initials: S
authors.lastname: Kaneko
authors.forename: Kimberly
authors.initials: K
authors.lastname: Myers
authors.forename: Shelby
authors.initials: S
authors.lastname: Kutty
authors.forename: Edythe B
authors.initials: EB
authors.lastname: Tham
mesh_terms: D000222:Adaptation, Physiological; D000416:Alberta; D018618:Echocardiography, Doppler, Color; D018729:Fontan Procedure / Q000009:adverse effects / Q000401:mortality; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D009200:Myocardial Contraction; D009329:Nebraska; D058327:Norwood Procedures / Q000009:adverse effects / Q000401:mortality; D015588:Observer Variation; D010166:Palliative Care; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016278:Ventricular Function, Right