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Second Congress of Cardiology and Angiology of Bosnia & Herzegovina

ASPIRIN THERAPY AND POSTOPERATIVE BLEEDING AFTER CORONARY ARTERY BY PASS GRAFTING
E. Mujicic, M. Kulic, F.Kucukalic, S.Straus, E. Donlic
Cardiac Surgery Clinic, University of Sarajevo Clinical Center, Bosnia and Herzegovina

Introduction

Aspirin, the salicylic ester of acetic acid, was introduced into medicine in 1899. It is used for its analgesic, antiinflammatory, antipyretic and antithrombotic effects. More recently, it has been shown that long-term ( 10 years) regular consumption of Aspirin may lower the risk of developing colorectal cancer- antiproliferative actions.
Most pharmacology texts state that Aspirin interferes with prostaglandin synthesis by irreversibly inhibiting cyclooxygenase, one of two major enzymes that act upon arachidonic acid.
Cyclooxygenase exist in 2 isozymes: Cyclooxygenase -1 or COX-1 and Cyclooxygenase -2 or COX-2. These isozymes are encoded by different genes, reside in different sites (COX-1 occurs in endoplasmatic reticulum, COX-2 is found in the nuclear envelope). COX-1 may be more important for hormonal regulation, hemostasis, and thrombosis, while COX-2 may be more important in the inflammatory response.
Aspirin acetylates serine in both isozymes. Acetylated COX-1 can no longer generate prostaglandins. Acetylated COX-2, however, retains the ability to generate metabolotes of arachidonic acid that are thought to possess antiproliferative effects.

Antiinflammatory action of Aspirin is belived to be a result of peripheral inhibition of prostaglandin synthesis, but Aspirin may also inhibit the action and synthesis of other mediators of inflammation.
Antipyretic effects of Aspirin are a result of inhibition of prostaglandin synthesis in the hypothalamus but also be result of Aspirin- induced peripheral vasodilation and sweating.
The analgesic property of Aspirin is thought to be mainly a result of periferal actions but direct effects on the CNS are possible.By inhibiting prostaglandin synthesis, Aspirin decreases the perception of pain.

Antithrombotic action
Plateled-derived COX-1 generates thromboxane A2, potent vasoconstrictor and platelet agonist. In contrast, entothelial cell COX-1 generates prostacyclin which possesses vasodilatory and antiplatelet actions. Inhibition of plateled COX-1 results in decreased platelet aggregation, leading to a prolonged bleeding time. This is desirable in patients with coronary artery disease.
Aspirin is recommended for chronic administration in patient with a known history of coronary artery disease, for myocardial infarcion prophylaxis, for the treatment of unstable angina, for arterial throboembolism prophylaxis in combination with warfarin in patients with prosthetic heart valves....
Platelets are unable to regenerate cyclooxygenase and show impaired aggregation for approximately seven days. Aspirin should be discontinued at least 1 week before surgery to minimize postoperative bleeding.

Material and methods

At Sarajevo Cardio-surgery Clinic we have observed two groups of patients:

  1. patients who stoped taking Aspirin 7 days and more than 7 days before elective surgery, and
  2. group of patients who, due to different reasons, have stoped taking Aspirin less than 7 days before surgery

Patients are picked randomly, at the age from 50 to 70 yeras, male, all patients had coronary artery disease and surgery on the coronary vessels. Surgery procedure have been the same for all patients ( open heart surgery with extra corporal circulation). Preoperative findings on coagulability of blood ( findings include INR, APTT, period of bleeding and coagulation) have been in normale range. They have no another disease which can influence on the cagulability of the blood.

Ahestethic technique was the same for all patients ( NLA), cardiopulmonalni by-pass lasted from 1 to 1,5 hours.
12 hours postoperative bleeding ( before starting with Heparine) was monitored on both groups of patients.

Results

First group of the patients ( they stoped taking Aspirin more than 7 days before surgery)

Patient number of by pass Aspirin stop before surgery Bleeding for 12 postop.hours
64 years 3 9 days 710ml
64 years 3 10 days 720ml
68 years 3 8 days 670 ml
57 years 3 8 days 800 ml
65 years 3 15 days 710ml
65 years 3 15 days 770 ml
62 years 4 10 days 590 ml
58 years 4 10 days 600ml
50 years 2 13 days 450 ml
58 years 3 1 month 520 ml
56 years 2 13 days 440 ml
58 years 1 7 days 490 ml
61 years 2 1 month 680 ml
59 years 3 1 month 740 ml
55 years 2 1 month 430 ml

Second groupe of the patients:

Patient number of by pass Aspirin stop before surgery Bleeding for 12 postop.hours
70 years 1 1 day 2200 ml
62 years 3 3 days 2350 ml
58 years 1 1 day 1600 ml
57 years 3 3 days 2150ml
61 years 3 1 day 1690 ml
58 years 4 4 days 2730 ml
69 years 3 4 days 1400 ml
62 years 3 2 days 2150 ml
62 years 3 3 days 1400ml
74 years 2 3 days 1400ml
57 years 2 1 day 1200ml
59 years 3 2 days 1300ml
65 years 2 3 days 1250 ml
61 years 3 2 days 1400ml
68 years 3 2 days 1300ml

Conclusion

The postoperative bleeding (12 hours after the operation) was increased in second group ( who had stopped taking aspirin less than one week before the operation). Bleeding was between 1200 ml and 2700 ml in this group. In the group where aspirin had been stopped more than one week before the CABG, bleeding was between 400 ml and 800 ml, in first 12 hours following the operation.

Due to these reasons, for the second group, we have used more units of blood, fresch frosen plasma, Trasylol , Minirin and K vitamin. The treatment of this group was more expensive.

Literature:

  1. Can pre-operative antiplatelet treatment increase the need of blood transfusions during open heart surgery? XXII Congress of the European Society of Cardiology; August 26-30 2000. Amsterdam
  2. The effect of aspirin therapy on thromboelastogram ( TEG) variables patients exposed to cardio-pulmonary bypass; J K Nanason, N McGill, D O Shaughnessy, M Herbertson, J Whiteside, R Gill Southampton General Hospital, Tremona Road, Sothampton, SO16 6YD
  3. Aspirin, Telegram 1/ 2001. Abstrakts
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