Introduction of a New Activating Clotting Time Test System at one Institution: Relationship with changes in Heparin Management and Postoperative Bleeding after Cardiac Surgery
Patteril M, Stafford-Smith M, Bute B, Welsby I
Duke University Medical Center, Durham, NC, USA
Discussion: We confirmed an association of increased heparin dosing during CPB with the change in ACT systems. Interestingly, this change was also associated with a statistically and clinically significant reduction in post operative bleeding during a period when no other major changes in practice occurred. A possible interpretation of our findings is that increased heparin dose inhibits clotting factor consumption during CPB, thereby improving postoperative hemostasis. However, further study is required to determine the cause of the relationship between higher heparin doses and reduced bleeding in this setting.

The Effects of Aprotinin on Twelve Different ACT Tests
K. Jones, F. Nasrallah, S. Graham, E. Darling, N. Clay, M. Hauser, B. Searles
SUNY Health Science Center, Syracuse, NY
Presented at AMSECT Annual Meeting, March 2002; JECT. 2002; 34: 41 - 78
Conclusion: “Each test responded uniquely to the presence of aprotinin in the
sample producing results ranging from 12 – 51% above nonaprotinized values. Also, several tests that were affected by aprotinin in heparinized blood samples were unaffected with unheparinized blood samples.”

Utility of a Novel Heparin/Protamine Titration for Monitoring Patients Undergoing Cardiopulmonary Bypass Surgery at two Clinical Sites

Walker C.T.1, Folk T.M.1, Balega S.2, Jones D.2, McGregor N.2, Cambell S.S.2, Coombs G2, Guyer K.E.3, Carville D.G.M.3, Ridgway H.4, Rullman, R.4
1Baptist Hospital, Pensacola, FL, 2St. Mary's Hospital, Kitchener, ON, 3Indiana University South Bend, South Bend, IN, 4Helena Laboratories, Beaumont, TX. Conclusion: The clinical feasibility studies demonstrate that the Helena AMK test system may be a suitable alternative for ACT testing of heparin and protamine sulphate during CPB surgical procedures.

Comparisons of Activated Clotting Times (ACT) Between Hemochron 801 and Helena Actalyke-Max ACT Systems
John G Toffaletti, Elizabeth McDonnell. Clinical Laboratory, Dept of Pathology
PO Box 3015; Duke University Medical Center, Durham, NC  27710.
Presented at the AACC Symposium: Critical Care and Point of Care Testing, Sept.2002, Monterey, California
Conclusion: “We conclude that (1) Precision was better by the Actalyke-MaxACT system than the Hem801, especially at higher levels of heparin. (2) ACT results by the Actlyk-MaxACT were shorter than ACT results by the Hem801. The presence of the three clotting activators and the lower angle of detection in the Actalyke instrument are likely explanations for this.  (3) Appropriate therapeutic ranges must be assessed for each patient group based on the consequences of under or over-heparinizing patients.”

New ACT Systems Vary in Precision and Bias Compared to an Existing Gold Standard
Welsby I.J., McDonnell E., El-Moalem H., Stafford-Smith M., Toffaletti J.
Departments of Anesthesiology and Pathology, Duke University Medical Center, Durham, NC.
Presented at Society of Cardiovascular Anesthesia Annual Meeting, April 2002
Conclusion: “Over the quoted range, Actalyke [AL] demonstrated superior precision than Hemochron Response [HR]. AL has previously been noted to read lower ACT values during hypothermic CPB (1). In addition, our data show significantly lower ACT values over ranges relevant to heparin anticoagulation management during PTCA and CPB. Using AL ACT values as minimum targets in existing protocols may provide a better safety margin for avoidance of thrombogenesis during the above procedures.”

Use of a New Activated Clotting Time (MAX-ACT) in Patients Undergoing Extracorporeal Circulation
Linda Shore-Lesserson, MD, Galina Leyvi, MD, Donna Harrington, RN, Frances Vela-Cantos, RN. Mount Sinai Medical Center, New York, NY, USA
Abstract reprinted from the December 1999 American Society of Anesthesia Journal
Conclusion: “ACT increases during hypothermia and hemodilution on CPB even though heparin levels do not increase. MAX-ACT did not increase possibly indicating a closer relationship to heparin levels on CPB. MAX-ACT requires further evaluation as a more accurate test of heparin's anticoagulant effect than ACT.”

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