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BACKGROUND: The incidence and implications of anti-heparin-platelet factor 4 (PF4) antibody seroconversion in the pediatric cardiac surgical population remain largely unexplored. We sought to prospectively characterize the incidence of seroconversion in two populations: neonates undergoing primary cardiac surgery and children undergoing reoperative cardiac surgery with a history of unfractionated heparin (UFH) exposure.

METHODS: One hundred and thirty-five consecutive patients were studied: Neonatal = 60 neonates, first time cardiac surgery. Reoperative (ReOp) = 75 children, reoperative cardiac surgery. Preoperative and postoperative day (POD) 5 and 10 blood samples were used to determine the presence of PF4 immunoglobulin (Ig)G, IgA, and IgM antibodies with enzyme-linked immunosorbent assay.

RESULTS: No anti-heparin/PF4 antibodies were detected preoperatively in either group. On POD 5, antibodies were present in 1 of 60 (1.7%) Neonatal; and in 12 of 75 (16%) ReOp; P = 0.006. On POD 10, antibodies were present in 1 of 60 (1.7%) Neonatal; and in 39 of 75 (52%) ReOp; P < 0.001. Seroconversion in ReOp patients on POD 10 was significantly associated (P = 0.03) with previous UFH exposures. Heparin-induced thrombocytopenia (HIT) was not diagnosed in any Neonatal patients. One ReOp patient (1.3%) seroconverted and developed HIT without thrombosis or skin lesions.

CONCLUSIONS: HIT is a rare occurrence in pediatric cardiac surgical patients. The incidence of anti-heparin-PF4 antibody seroconversion in children undergoing reoperation is approximately 50% at 10 days postoperatively, a finding similar to that reported in adult cardiac surgical patients. Both age and previous UFH exposure correlate with this rate of seroconversion. In contrast, the rate of seroconversion in neonates undergoing first time surgery is substantially lower.

The Day We Found the Universe
Written by Marcia Bartusiak

From one of our most acclaimed science writers: a dramatic narrative of the discovery of the true nature and startling size of the universe, delving back past the moment of revelation to trace the decades of work--by a select group of scientists--that made it possible.
On January 1, 1925, thity-five-year-old Edwin Hubble announced findings that ultimately established that our universe was a thousand trillion times larger than previously believed, filled with myriad galaxies like our own. It was a realization that reshaped how humans understood their place in the cosmos. Six years later, continuing research by Hubble and others forced Albert Einstein to renounce his own cosmic model and finally accept the astonishing fact that the universe was not immobile but instead expanding. The story of these interwoven discoveries includes battles of will, clever insights, and wrong turns made by the early investigators in this great twentieth-century pursuit, from the luminaries (Einstein, Hubble, Harlow Shapley) to the lesser known: Henrietta Leavitt, who discovered the means to measure the vast dimensions of the cosmos . . . Vesto Slipher, the first and unheralded discoverer of the universe’s expansion . . . Georges Lemaître, the Jesuit priest who correctly interpreted Einstein’s theories in relation to the universe . . . Milton Humason, who, with only an eighth-grade education, became a world-renowned expert on galaxy motions . . . and others.
Here is the watershed moment in our cosmic history, splendidly arising from the exceptional combination of human curiosity, intelligence, and enterprise.