title: External counterpulsation of a systemic-to-pulmonary artery shunt increases coronary blood flow in neonatal piglets.
abstract: BACKGROUND
  Systemic-to-pulmonary artery shunt (SPS) palliation reduces coronary blood flow (CBF), which may precipitate myocardial ischemia postoperatively.
  
  
  OBJECTIVE
  Counterpulsation (CP) of SPS augments CBF.
  
  
  METHODS
  Seven neonatal piglets (4.3 ± 0.23 kg) underwent sternotomy and ductus ligation. With a 5-mm polytetrafluoroethylene graft, SPS was created from innominate to pulmonary artery. A rigid shell holding a 9.5-mm diameter balloon was placed around the graft for CP. Using electrocardiographic signal, CP was initiated to trigger balloon inflation/deflation during the diastolic/systolic intervals, respectively. Instantaneous proximal and distal pulmonary artery and mid-anterior descending coronary artery flow rates were measured using transit time flow probes. Blood pressure and flow rates were recorded during three states: shunt closed, shunt open, and shunt open with CP.
  Friedman's test and repeated measures analysis of variance.
  
  
  RESULTS
  Diastolic pressure decreased significantly with the shunt open (39 ± 8.4 to 28 ± 4.5 mm Hg, P = .05), then increased with CP (33 ± 2.3 mm Hg, P = .03). Median ratio of pulmonary to systemic flow (Qp/Qs) was 1.19, 1.9, and 1.53 with shunt closed, open, and open with CP, respectively. With CP, both diastolic coronary flow per minute (P = .018) and average diastolic flow rate per diastolic interval (P = .03) increased as well as total coronary flow per minute (P = .066; 19.6% ± 11.7%, 25.2% ± 17.0%, and 15.4% ± 13.9% change from shunt open, respectively). The percentage increase in average diastolic flow rate per diastolic interval correlated strongly with Qp/Qs (R (2) = .838).
  
  
  CONCLUSIONS
  In this model of SPS, CP increased diastolic blood pressure and CBF while maintaining significant augmentation of pulmonary blood flow (Qp/Qs). Shunt CP may aid in early postoperative management of palliative congenital heart disease.
authors.affiliation: The Heart Center at Arnold Palmer Hospital for Children, Orlando, FL, USA College of Medicine at the University of Central Florida, Orlando, FL, USA College of Engineering and Computer Science, University of Central Florida, Mechanical and Aerospace Engineering, Orlando, FL, USA william.decampli@orlandohealth.com.
authors.forename: William M
authors.initials: WM
authors.lastname: DeCampli
authors.affiliation: College of Medicine at the University of Central Florida, Orlando, FL, USA.
authors.forename: Virgil
authors.initials: V
authors.lastname: Secasanu
authors.affiliation: The Heart Center at Arnold Palmer Hospital for Children, Orlando, FL, USA.
authors.forename: I Ricardo
authors.initials: IR
authors.lastname: Argueta-Morales
authors.affiliation: College of Engineering and Computer Science, University of Central Florida, Mechanical and Aerospace Engineering, Orlando, FL, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Cox
authors.affiliation: The Heart Center at Arnold Palmer Hospital for Children, Orlando, FL, USA.
authors.forename: Constantine
authors.initials: C
authors.lastname: Ionan
authors.affiliation: College of Engineering and Computer Science, University of Central Florida, Mechanical and Aerospace Engineering, Orlando, FL, USA.
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Kassab
mesh_terms: D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000601:surgery*; D015908:Counterpulsation; D006330:Heart Defects, Congenital / Q000601:surgery; D017202:Myocardial Ischemia / Q000209:etiology / Q000517:prevention & control*; D011183:Postoperative Complications / Q000517:prevention & control*; D011651:Pulmonary Artery / Q000502:physiology / Q000601:surgery*; D011652:Pulmonary Circulation; D013552:Swine; D058017:Vascular Grafting / Q000379:methods*
keywords: animal model; circulatory hemodynamics; congenital heart disease; device; innominate-to-pulmonary artery shunt