title: Intravenous vitamin K1 prior to orthotopic heart transplantation: effects in vivo and in vitro.
abstract: BACKGROUND
  Vitamin K1 is used to reverse warfarin's anticoagulant action. It is unclear whether intravenous vitamin K1 is safe or efficacious prior to urgent cardiac surgery.
  
  
  METHODS
  We retrospectively and prospectively examined the effects of preoperative intravenous vitamin K1 in vivo (administered for warfarin reversal immediately before heart transplantation) on intraoperative blood product utilization, hemodynamics and coagulation parameters. We also determined the direct effects of vitamin K1 in vitro on rings of human saphenous vein and internal mammary artery.
  
  
  RESULTS
  In the retrospective limb, 29 of 67 patients were administered vitamin K1 preoperatively via slow intravenous infusion. Vitamin K1 administration produced no adverse outcome but did not affect subsequent perioperative use of blood products. In the prospective limb (n = 10), vitamin K1 significantly (P < or = 0.01, Student t-test) altered mean arterial pressure (from 85 +/- 15 to 76 +/- 16 mmHg), systemic vascular resistance (from 1364 +/- 308 to 1078 +/- 252 dyn.s.cm-5), and cardiac index (from 2.3 +/- 0.3 to 2.7 +/- 0.3 L/min/m2) (mean +/- SD). Significant decreases in prothrombin time (19.8 +/- 2.7 to 17.7 +/- 1.8 s) and activated clotting time (164 +/- 26 to 137 +/- 24 s) were observed at 60 min. In vitro vitamin K1 (10(-7) to 10(-4) M) had no effect on the tone of noradrenaline-constricted rings.
  
  
  CONCLUSIONS
  Vitamin K1, administered by intravenous infusion prior to heart transplantation, did not alter subsequent perioperative blood product administration. Vitamin K1 rapidly reversed the anticoagulant effect of warfarin and produced modest hemodynamic changes. The decrease in systemic vascular resistance is probably not due to a direct effect of vitamin K1 on vascular smooth muscle.
authors.affiliation: Department of Anesthesiology, Temple University Hospital, Philadelphia, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Barnette
authors.forename: W W
authors.initials: WW
authors.lastname: Wendling
authors.forename: J W
authors.initials: JW
authors.lastname: Schweiger
authors.forename: N W
authors.initials: NW
authors.lastname: Brister
authors.forename: S A
authors.initials: SA
authors.lastname: Schartel
authors.forename: D
authors.initials: D
authors.lastname: Chen
authors.forename: C A
authors.initials: CA
authors.lastname: Shuman
authors.forename: J B
authors.initials: JB
authors.lastname: McClurken
authors.forename: V
authors.initials: V
authors.lastname: Jeevanandam
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D001780:Blood Coagulation Tests; D001803:Blood Transfusion; D005260:Female; D016027:Heart Transplantation; D006439:Hemodynamics / Q000187:drug effects; D006490:Hemostatics / Q000008:administration & dosage*; D006801:Humans; D066298:In Vitro Techniques; D007262:Infusions, Intravenous; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011300:Preoperative Care; D011446:Prospective Studies; D012189:Retrospective Studies; D012501:Saphenous Vein / Q000187:drug effects / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014812:Vitamin K / Q000008:administration & dosage*; D014859:Warfarin / Q000008:administration & dosage
chemical_list: D000925:Anticoagulants; D006490:Hemostatics; D014812:Vitamin K; D014859:Warfarin