1. A pharmaceutical composition comprising a pharnlaceutically acceptable carrier and pharmaceutically effective amounts of a compound having anti-Xa activity and a platelet aggregation antagonist compound. 2. The pharmaceutical composition according to claim 1 wherein the compound having anti-Xa activity is a low molecular weight heparin. 3. The pharmaceutical composition according to claim 1 wherein the low molecular weight heparin is selected from the group consisting of enoxaparin, nardroparin, dalteparin, certroparin, parnaparin, reviparin, ardeparin/RD heparin/ RDH or tinzaparin. 4. The pharmaceutical composition according to claim 1 wherein the low molecular weight heparin is enoxaparin. 5. The pharmaceutical composition according to claim 1 wherein the compound having anti-Xa activity is a heparinoid compound. 6. The pharmaceutical composition according to claim 1 wherein the heparinoid compound is danaparoid. 7. The pharmaceutical composition according to claim 1 wherein the platelet aggregation antagonist compound is abciximab, N-[N- [N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl] aspartyl]-L-β-cyclohexyl alanine, N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl] aspartyl]-L-β-cyclohexyl alanine amide or N-(n-butylsulfonyl)-4-(piperidin-4-ylbutyloxy)-L-phenylalanine. 8. The pharmaceutical composition according to claim 7 wherein the platelet aggregation antagonist compound antagonist is abciximab. 9. The pharmaceutical composition according to claim 7 wherein the platelet aggregation antagonist compound is N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl] aspartyl]-L-β-cyclohexyl alanine. 10. The pharmaceutical composition according to claim 7 wherein the platelet aggregation antagonist compound is N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl] aspartyl]-L-β-cyclohexyl alanine amide. 11. The pharmaceutical composition according to claim 7 wherein the platelet aggregation antagonist compound is N-(n-butylsulfonyl)-4-(piperidin-4-ylbutyloxy)-L-phenylalanine. 12. A method of treating or preventing a physiological condition associated with a thrombosis related ischemic disorder in a patient comprising administering to said patient pharmaceutically effective amounts of a compound having anti-Xa activity and a platelet aggregation antagonist compound. 13. The method of claim 12 wherein the physiological condition is selected from stroke, atherosclerosis, angiogenesis, thrombosis, a thromboembolic condition, disseminated intravascular coagulation, peripheral arterial occlusive disease, hemodialysis, an extra-corporeal circulation requirement associated with a surgical procedure, tissue damage caused by phospholipases A2, an acute coronary syndrome, or a thromboembolic syndrome associated with cancer, sepsis or obstetrical complications. 14. The method of claim 13 wherein the physiological condition is the acute coronary syndrome. 15. The method of claim 14 wherein the acute coronary syndrome is unstable angina or myocardial infarction. 16. The method of claim 12 wherein the treating or preventing occurs in the course of coronary artery bypass surgery or percutaneous transluminal coronary angioplasty. 17. The method of claim 12 wherein the treating or preventing occurs in the course of percutaneous transluminal coronary angioplasty. 18. The use of pharmaceutically effective amounts of a compound having anti-Xa activity and a platelet aggregation antagonist compound in the preparation of a medicament for treating or preventing a physiological condition associated with thrombosis related ischemic disorder. 19. The use according to claim 18, wherein the physiological condition is the acute coronary syndrome. 20. The use according to claim 19 wherein the acute coronary syndrome is unstable angina or myocardial infarction. 21. The use according to claim 18 wherein the treating or preventing occurs in the course of coronary artery bypass surgery or percutaneous transluminal coronary angioplasty. 22. The use according to claim 18 wherein the treating or preventing occurs in the course of percutaneous transluminal coronary angioplasty. 23. A kit for treating or preventing a physiological condition associated with thrombosis related ischemic disorder, said kit comprising a plurality of separate containers, wherein at least one of said containers contains a compound having anti-Xa activity and at least another of said containers contains a platelet aggregation antagonist compound, and said containers optionally contain a pharmaceutical carrier. 24. A kit according to claim 23 wherein of said containers at least one of said containers should contain the compound having anti-Xa activity without the presence of the platelet aggregation antagonist compound, and at least another of said containers should contain the platelet aggregation antagonist compound without the presence of the compound having anti-Xa activity. 25. A product containing a compound having anti-Xa activity and a platelet aggregation antagonist compound as a combined preparation for simultaneous, separate or sequential use for treating or preventing a physiological condition associated with thrombosis related ischemic disorder. 26. A use of a compound having anti-Xa activity and a platelet aggregation antagonist compound together in therapy for treating or preventing a physiological condition associated with thrombosis related ischemic disorder.