title: Acute effects of the ACE inhibitor enalaprilat on the pulmonary, cerebral and systemic blood flow and resistance after the bidirectional cavopulmonary connection.
abstract: BACKGROUND
  The bidirectional cavopulmonary connection (BCPC) is used in the staged palliation of univentricular hearts and places the cerebral and pulmonary vascular beds in series. Angiotensin-converting enzyme inhibitors (ACEI) are often used in this complex circulation, but the effects of their vasodilation are unclear.
  
  
  OBJECTIVE
  Assessment of the acute response of perfusion pressure, flow and resistance across the systemic, cerebral and pulmonary vascular beds to ACEI in patients with a BCPC.
  
  
  METHODS
  Prospective interventional study.
  
  
  METHODS
  Single tertiary care centre.
  
  
  METHODS
  12 patients with a BCPC (median age 28 months, weight 11.8 kg) undergoing a pre-Fontan catheterisation with MRI measurement of flows.
  
  
  METHODS
  Intravenous enalaprilat 0.005 or 0.01 mg/kg.
  
  
  RESULTS
  Enalaprilat increased descending aorta flow (median 21.6%, p=0.0005), decreased total pulmonary vein flow (median 10.6%, p=0.025), and both superior caval vein flow (median 8.6%, p=0.065) and aortopulmonary collateral flow (median 15.5%, p=0.077) tended to decrease. Total cardiac output was unchanged (p=0.57). Systemic vascular resistance (median 41.9%, p=0.0005) and cerebral vascular resistance (median 23.4%, p=0.0005) decreased, but pulmonary vascular resistance (p=0.73) showed little change. There was evidence of autoregulation of cerebral blood flow. The proportion of descending aortic flow to total cardiac output increased (median 27 to 35%, p=0.001). Systemic oxygen saturation decreased from 87% to 83% (p=0.02).
  
  
  CONCLUSIONS
  Enalaprilat did not increase total cardiac output but redistributed flow to the lower body, with a concomitant decrease in arterial oxygen saturation. It is difficult to increase cardiac output in patients with a BCPC and ACEI should be used with caution in those with borderline aortic saturations.
authors.affiliation: The Labatt Family Heart Centre, Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto School of Medicine, Canada. kyong-jin.lee@sickkids.ca
authors.forename: Kyong-Jin
authors.initials: KJ
authors.lastname: Lee
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
authors.forename: Helen
authors.initials: H
authors.lastname: Holtby
authors.forename: Brian
authors.initials: B
authors.lastname: Grant
authors.forename: Dariusz
authors.initials: D
authors.lastname: Mroczek
authors.forename: Derek
authors.initials: D
authors.lastname: Wong
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
authors.forename: Leland N
authors.initials: LN
authors.lastname: Benson
authors.forename: Rajiv R
authors.initials: RR
authors.lastname: Chaturvedi
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D006328:Cardiac Catheterization / Q000379:methods; D002302:Cardiac Output / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D002675:Child, Preschool; D015773:Enalaprilat / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D018610:Heart Bypass, Right; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006352:Heart Ventricles / Q000002:abnormalities; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007223:Infant; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D011652:Pulmonary Circulation / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D015773:Enalaprilat