The Penn State pediatric ventricular assist device (PVAD) was designed to meet the need for a pediatric bridge-to-transplant device. While animal studies are encouraging, thrombus formation has been observed and patterns of platelet deposition are further explored. After PVAD ovine studies, blood sacs are evaluated using immunofluorescence and confocal microscopy, environmental scanning electron microscopy (ESEM), and optical profilometry (OP). Data from confocal, ESEM, and OP were correlated to find that surface topography can promote deposition.