Modified microsample ACT test for heparin monitoring

Chi Miau Pan, David Jobes, Dan Van Riper, John David Ogilby, Chung Yuan Lin, Jan Horrow, Roger Blumenthal, Marsha Mendoza, Frank LaDuca

Research output: Contribution to journalArticle


The activated clotting time (ACT) is a standard method of heparin monitoring during cardiac angioplasty and cardiac surgery. A modified ACT (ACT+) which employs a microsample blood volume (0.05 ml) and yields faster clotting time results than a conventional Hemochron ACT was evaluated and compared to the standard ACT. The ACT+, determined using a single channel general purpose analyzer (Hemochron Jr.), employs a plastic cuvette containing dried ACT reagents (kaolin-silica-phospholipid). In vitro evaluation of heparinized normal donor blood demonstrated the test insensitivity to aprotinin. Using split blood specimens, duplicate ACT and ACT+ were performed (n=92) and a correlation between the two was established. In evaluation of 79 cardiac surgery and 53 angioplasty patients, good correlation was observed between ACT+ and Hemochron ACT (r=0.93, n=574). Mean versus difference plots demonstrated an improved reproducibility of the ACT+ (Mean SD=35 seconds) compared to the ACT (Mean SD=53 seconds), presumably due to automation of the blood sample sizing and blood/reagent mixing. These studies indicate that the microsample ACT+ is an alternative to the conventional ACT with an advantage of small sample requirement and rapid reproducible results.

Original languageEnglish (US)
Pages (from-to)16-20
Number of pages5
JournalJournal of Extra-Corporeal Technology
Issue number1
StatePublished - Jan 1 1996
Externally publishedYes



  • activated clotting time
  • anticoagulation
  • aprotinin
  • dose-response
  • heparin

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Health Professions (miscellaneous)
  • Cardiology and Cardiovascular Medicine

Cite this

Pan, C. M., Jobes, D., Van Riper, D., Ogilby, J. D., Lin, C. Y., Horrow, J., Blumenthal, R., Mendoza, M., & LaDuca, F. (1996). Modified microsample ACT test for heparin monitoring. Journal of Extra-Corporeal Technology, 28(1), 16-20.