Heparin is introduced in cardiac patient with pregnancy:(LQ)
|D||At the time of labour|
a. Heparins (Hepa=liver) are most commonly used parenteral anticoagulants.
b. The drug acts by inhibiting the activation of clotting factors 2,7,9,10, 11, 12 and activates antithrombin-3.
c. The drug is not absorbed by oral route and therefore is given either by SC or IM route, the drug is not given by intramuscular route. Now days, however a drug that selectively blocks Xa factor called rivoroxaban is available, It can be given orally.
d. Half life is 1 hour and the drug is 99% protein bound. It follows zero order kinetics. Since, the action of the drug starts instantaneously therefore; heparin is used during the acute phase while warfarin is waiting to take its effect.
a. Most common side effect of heparins is bleeding and earliest manifestation is hematuria.
b. The drug produces alopecia and osteomalacia like warfarin. Both bleeding and clotting can occur. Bleeding occurs because of heparin induced thrombocytopenia (HIT).
c. It is treated by argatroban, which is a direct thrombin inhibitor. Clotting occurs because; some of the platelets are injured and are not dead.
d. Dead platelets are cleared by immune cells but the injured platelets combine with each other leading to clotting.
e. Heparins should be stopped at bleeding or clotting. Thrombocytopenia or mild to moderate degree is not an indication of stopping the drug. Clotting is treated by thrombolytic drugs.
f. Serious bleeding is treated by antiplasmin drugs and the heparin is stopped. There is an antidote of heparin available named protamine sulphate. However, it is also a low molecular weight heparin.
g. Therefore, it should only rarely be used. Hyperkalemia also occurs during heparin therapy.
Heparin is the drug of choice for anticoagulant action during pregnancy.
For patients at risk of thromboembolism and those who have prosthetic heart valves, guidelines from the American College of Chest Physicians (ACCP) consensus on antithrombotic therapy recommend one of three regimens:
a. Aggressive adjusted-dose low molecular weight heparin (LMWH) throughout pregnancy with monitoring of anti-Xa levels;
b. Adjusted-dose subcutaneous UFH throughout pregnancy with monitoring of the aPTT;
Use of either subcutaneous LMWH or UFH between 6 and 12 weeks and close to term (i.e., at week 36 and thereafter)