• Shyamal Asher, Andrew Maslow, Vikas Mishra, Devon Flaherty, Geoffrey Hayward, Stephanie Whiteneck, Tracey Cheves, and Joseph Sweeney.
• Department of Anesthesiology, Rhode Island Hospital, Providence, RI. Electronic address: ashershy@gmail.com.
• J. Cardiothorac. Vasc. Anesth. 2022 Dec 1; 36 (12): 428142884281-4288.

ObjectivesTo determine the onset of heparin anticoagulation, using 2 different measures of activated clotting times (ACT), thromboelastography (TEG; R-time), and anti-Xa levels, after administering low- (100 U/kg) and high- (300 U/kg) dose intravenous (IV) heparin to patients undergoing transcatheter aortic valve replacement (TAVR) and cardiac surgery, respectively.DesignProspective study.SettingSingle academic institution.ParticipantsPatients with normal baseline coagulation presenting for TAVR or cardiac valve surgery.InterventionsCoagulation studies were performed at baseline, 30 seconds, 90 seconds, and 180 seconds after IV heparin administration. The tests included iSTAT (iACT) and Hemochron ACT (hACT), TEG R-Time, and anti-Xa levels. At the authors' institution, anti-Xa is the preferred measure of heparin anticoagulation when time permits. ACT, a rapid point- of-care test, is used to assess intraprocedural anticoagulation.Measurements And Main ResultsAfter both low- and high-dose heparin, there are peak increases in ACT and anti-Xa at 30 seconds, followed by a decline at 90 seconds and plateau at 180 seconds. The TEG R-time remained elevated (>80 minutes) throughout. For TAVR cases, all anti-Xa was >1.5 IU/mL, and was associated with an iACT >180 seconds and an hACT >200 seconds. For cardiac valve surgery cases, all anti-Xa was >2.4 and associated with an iACT >420 seconds and and hACT >340 seconds. Compared with hACT, iACTs were significantly lower at all time points after low-dose heparin, but not after high-dose heparin.ConclusionsIn this pilot study, heparin anticoagulation was detected as early as 30 seconds after IV administration, based on ACT, anti-Xa levels, and TEG R-time.Copyright © 2022 Elsevier Inc. All rights reserved.

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