Variety of anatomic lesions not amenable to two ventricle repair (valve atresia/hypoplasia, outflow tracthypoplasia, etc)

Complete mixing of systemic and pulmonary venous returntypically at atrial or ventricular level

Aortic and pulmonary blood flow are in parallel circuits

Frequently there is an obstruction to outflow tract

Most are dependent on prostaglandins (PGE) until surgery

Hypoplastic left heart syndrome

Example of one type of single ventricle preoperatively

Balancing the circuits preoperatively

Goal to provide enough pulmonary flow for adequate oxygenation (70-80%) and enough systemic flow for adequate oxygen delivery to prevent acidosis without an excessive volume load to single ventricle

Ways to increase PBF

  • Alkalosis (pH > 7.4)
  • Oxygen
  • Nitric oxide
  • Sedation/ paralysis (relaxes vascular bed)

Ways to decrease PBF

  • Acidosis (pH < 7.35)
  • Permissive hypercarbia (CO2 50-60)
  • Subambient oxygen (nitrogen or CO2)
  • Increase PEEP/ MAP

Ways to increase SBF

  • Vasodilators (ex: Nipride)     
  • Afterload reduction (ex: Milrinone)  
  • Sedation/paralytics

Ways to decrease SBF

  • Phenylephrine
  • Norepinephrine

*PBF = pulmonary blood flow
*SBF = systemic blood flow

General goals of surgical repair

  1. Unobstructed systemic blood flow ( to minimizeventricular hypertrophy)
  2. Limited PBF ( to minimize ventricular volume load andrisk of pulm artery HTN)
  3. Unobstructed venous return (to minimize left atrial andsecondary pulm artery HTN)
  4. Minimize likelihood of pulmonary artery distortion
  5. Prevent arrhythmias
  6. Avoid AV valve regurgitation