This study compares the results of current standard coagulation measurement devices to the Quantra System, a new device, using small amount of extra blood obtained during routine blood draws in cardiac surgery patients.

HemoSonics is developing a novel POC diagnostic device, the Quantra System, to perform whole blood coagulation analysis and which is suitable for use in surgical and intensive care settings. The Quantra System employs a patented technology named sonorheometry, which was invented at the University of Virginia. Sonorheometry uses ultrasound pulses to characterize the dynamic changes in viscoelastic properties of a blood sample during coagulation and clot lysis. The initial assay performed on the Quantra System will be the surgical assay for monitoring hemostasis during major surgical procedures in adult patients.

A clinical study will be conducted to evaluate the analytical performance as well as provide a preliminary evaluation of the performance comparability of the HemoSonics' device as compared to existing coagulation monitoring technology in heart surgery. This study will be performed at HemoSonics and the University of Virginia Health System and will involve patients undergoing cardiac surgery requiring bypass.

Inclusion Criteria:

• Subject is scheduled for cardiac surgery involving bypass circuit
• Subject is older than 18 years
• Subject is willing to participate and he/she has signed a consent form

Exclusion Criteria:

• Subject is unable to provide written informed consent
• Subject is incarcerated at the time of the study
• Subject is affected by any condition that, in the opinion of the surgical team, may pose additional risks
• Patients with renal disease (defined as serum creatinine greater than 1.5 mg/dl)
• Patients with history of active liver disease
• Patients on emergency cases
• Patients on heparin anticoagulation before the beginning of the study

Participants for this study will be recruited at UVA. The subject population will be representative of the local racial and ethnic population.