Activated clotting time

E.J. Cohen, L.J. Camerlengo, and J.P. Dearing, Activated clotting times and cardiopulmonary bypass I. The effect of hemodilution and hypothermia upon activated clotting time. J. Extra Corpor. Technol. 12, 139-141 (1980). 

The recommended dosage of bivalirudin is an intravenous (IV) bolus dose of 0.75 mg/kg. This should be followed by an infusion of 1.75 mg/kg/h for the duration of the PCI procedure. Five minutes after the bolus dose has been administered, an activated clotting time (ACT) should be performed and an additional bolus of 0.3 mg/kg should be given if needed. GPIIb/llla inhibitor administration should be considered in the event that any of the following conditions are present ... 

Percutaneous coronary intervention IV Infusion Initially, 25 mcg/kg/min and administer bolus of 350 mcg/kg over 3-5 min. ACT (activated clotting time) checked in 5-10 min following bolus. If ACT is less than 300 sec, give additional bolus 150 mcg/kg, increase infusion to 30 mcg/kg/min. If ACT is greater than 450 sec, decrease infusion to 15 mcg/kg/min. Once ACT of 300-450 sec achieved, proceed with procedure. 

In clinical trials, the dose of bivalirudin was not titrated according to the activated clotting time (ACT)... 

Activated partial thromboplastin time (aPTT) or protamine activated clotting time (ACT) 15 min after dose, then in several hr... 

Activated clotting time, aPTT, BP, cardiac function, and other coagulation tests... 

Most major bleeding occurs at arterial access site for cardiac catheterization prior to pulling femoral artery sheath, discontinue heparin for 3-4 hr and document activated clotting time (ACT) <180 sec or aPTT <45 sec achieve sheath hemostasis >4 hr before discharge... 

Activated clotting time (ACT) and activated partial thromboplastin time (aPTT) are relatively unaffected by LMWH. Anti-Xa activity can be used to monitor anticoagulation activity, but this is expensive and time-consuming and is seldom indicated. Although protamine has some effect on LMWH, about 60-80% of the antithrombotic activity will persist. This is because of the reduced protamine binding to these drugs and because only the anti-IIa activity is completely reversed whereas anti-Xa activity is only partially neutralised. 

Bleeding complications were doubled with GPIIb/llla blockade in early studies (8,10). However, the use of weight-adjusted low dose of heparin [activated clotting time (ACT) target of 200-250 seconds] and optimal management of vascular access site (rapid sheath removal within four to... 

Abbreviations ACT, activated clotting time GP, glycoprotein IV, intravascular. Source From Ref. 3, ... 

Cheneau E, Canos D, Kuchulakanti PK, et al, Value of monitoring activated clotting time when bivalirudin is used as the sole anticoagulation agent for percutaneous coronary intervention, AmJ Cardiol 2004 94 789-792,... 

Brener SJ, Moliterno DJ, Lincoff AM, et al, Relationship between activated clotting time and ischemic or hemorrhagic complications analysis of 4 recent randomized clinical trials of percutaneous coronary intervention, Circulation 2004 ... 

Casserly IP Kereiakes DJ, Gray WA, et al, Point-of-care ecarin clotting time versus activated clotting time in correlation with bivalirudin concentration, Thromb Res 2004 I 13 1 15-121,... 

Bivalirudin is a direct thrombin inhibitor that has found utility for reducing the rate of acute reocclusion in patients treated with PCI. It is preferential to heparin in PCI when HIT is present. This drug is a derivative of hirudin, which is a dedicated thrombin inhibitor with no other in vivo activities of significance. The molecule is semisynthetic the C-terminal of hirudin is linked by a polyglycine spacer to the tetrapeptide region of the N-terminal that reacts with the thrombin active site (22). It is monitored by the activated clotting time test. Its pharmacologic properties are shown in Table I. 

Chew DR Bhatt DL, Lincoff AM, et al. Defining the optimal activated clotting time during percutaneous coronary intervention aggregate results from 6 randomized, controlled trials. Circulation 2001 103 961 -966. 

The main cause of debate at present with regard to UFH centers on the amount used peri-PCI. The level of anticoagulation produced by UFH is measured by the activated partial thromboplastin time and activated clotting time (ACT), the latter being available in the cardiac catheter laboratory as a near-patient test. 

Abbreviations ACS, acute coronary syndrome ACT, activated clotting time BP, blood pressure CTO, chronic total occlusion i.v., intravenous MI, myocardial infarction NSTEMI, non-ST-segment elevation myocardial infarction PCI, percutaneous coronary intervention RCA, right coronaiy artery STEMI, ST-segment elevation myocardial ... 

Heparin is administered intravenously at the start of a PPI procedure either as a standard bolus injection or, as more appropriately, a weight-adjusted dose regimen. No consistent dosing regimen has been tested in a well-controlled study. The anticoagulant effect of heparin during PPI should be monitored by the activated clotting time (ACT). 

For premedication aspirin 300 mg twice a day 48 hours prior to the procedure and a loading dose of clopidogrel 300 mg (or ticlopidine 250 mg) is recommended. Endocarditis prophylaxis with a first generation cephalosporin (e.g., cefuroxime, 1, 5 g, i.v.) should be administered before and after intervention. After transseptal puncture, 10,000 units of heparin are administered. An activated clotting time of 200-300 seconds is desirable. 

In preparation for chest discomfort during alcohol injection, prophylactic analgesic medication (eg. fentanyl 25 mm IV) is administered. Antithrombotic prophylaxis with intravenous, weight-adjusted heparin is given to maintain an activated clotting time of 200 to 250 seconds. 

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