The purpose of this study is to investigate the pharmacokinetics of cefazolin using both plasma and microdialysate sampling methods in children with single ventricle physiology undergoing their second palliation procedure. This will provide data to determine if the current standard dosing regimen of cefazolin is adequate to achieve and maintain tissue concentrations greater than the minimum inhibitory concentrations (MIC) for common post-surgical pathogens that cause Surgical Site Infections (SSIs).

This study aims to sample interstitial fluid (IF) of infants undergoing superior cava-pulmonary anastomosis (either Glenn or Hemi-Fontan) cardiac surgical procedures who receive cefazolin as their surgical prophylactic antibiotic. Cefazolin concentrations will then be determined in both microdialysate and plasma samples and used to define the pharmacokinetics of cefazolin at the tissue level and compare that to plasma pharmacokinetics. In addition, the data gathered will be used to assess how cardiopulmonary bypass (CPB), deep hypothermic cardiac arrest (DHCA), and modified ultrafiltration (MUF) affect tissue penetration of the prophylactically administered cefazolin.

The study involves the use of microdialysis (MD) and plasma sampling methods to determine the pharmacokinetic properties of cefazolin when used as a prophylactic antibiotic during the second palliation procedure (superior vena cava-pulmonary anastomosis) for infants with single ventricle physiology. This requires the use of microdialysis (MD) catheters inserted into the left deltoid muscle in eligible subjects after the induction of general anesthesia as well as collection of microdialysate and blood samples throughout the duration of the procedure. Cefazolin will be administered as standard of care. Cefazolin concentrations in the collected samples will be measured via a validated high-performance liquid chromatography (HPLC) and mass spectrometry assay. Pharmacokinetic analyses will be performed.

Inclusion Criteria:

• Males or females with single ventricle physiology undergoing their second palliation procedure (typically performed between 3-6 months of age)
• Use of cefazolin as the prophylactic antibiotic during the operation
• Written informed consent provided by the parent or legal guardian

Exclusion Criteria:

• Use of prophylactic antibiotic other than cefazolin during the operation
• Anatomic or other abnormalities of the upper arm that would preclude insertion of a microdialysis catheter
• Known renal or hepatic function

Males or females with single ventricle physiology undergoing their second palliation procedure (typically performed between 3-6 months of age)