You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
Time-related anticoagulation after regional and systemic administration of heparin in patients undergoing aortoiliac surgery.
Abstract 1:
Heparin anticoagulation during cardiovascular surgical procedures remains poorly investigated and understood . The objective of this investigation was to assess the effectiveness of three methods of heparin administration . Heparin sulfate ( 75 IU/kg ) administered to patients undergoing aortoiliac surgery was r and omised to one of three methods : Group I ( n = 9 ) heparin was injected into a central venous line 5 minutes before infrarenal aortic clamping ; Group II ( n = 9 ) heparin was injected into the distal aneurysm immediately after infrarenal aortic clamping ; and Group III ( n = 8) heparin was injected into a central venous line immediately after infrarenal aortic clamping . Blood sample s were analysed for anticoagulant activity from both the upper and lower extremities at 5 , 15 , 30 , 60 , and 120 minutes after heparin administration . Anticoagulation , as measured by aPTT , antifactor Xa levels , and ACT , was achieved in all three groups by 5 minutes , but initially with lower heparin activity ( measured as antifactor Xa ) in the upper extremity ( Group II ) and lower extremity ( Group III ) , respectively . These differences were also evident in ACT and aPTT determinations .  Intravenous heparin administration prior to aortic cross-clamping achieves excellent anticoagulation ( anti-factor Xa approximately 1 U/ml ) in both upper and lower extremities after 5 minutes . With regional administration , rapid heparin redistribution occurs , but it takes longer to achieve the same level of anticoagulation distant from the site of administration . Nevertheless , from a practical perspective the method of administration does not appear to have a great influence on the eventual achievement of adequate anticoagulation


Title 2:
Coagulopathy and Hyperfibrinolysis in Ruptured Abdominal Aortic Aneurysm Repair
Abstract 2:
Perioperative hemorrhage is one of the principal causes of death in patients with ruptured abdominal aortic aneurysm ( AAA ) . This study examines perioperative coagulation and fibrinolysis in patients undergoing ruptured AAA repair complicated by coagulopathy . Eight patients ( 8 men of median age 74 , range 69 - 87 , years ) who developed clinical and laboratory evidence of coagulopathy during attempted repair of ruptured infrarenal AAA were prospect ively studied .  Platelet count , fibrinogen , clotting times , prothrombin fragment ( PF ) 1 + 2 , and tissue plasminogen activator ( t-PA ) and plasminogen activator inhibitor ( PAI ) activities  were measured preoperatively , immediately before , and 5 min and 24 hr after aortic declamping . Six patients died , three intraoperatively , one within 24 hr , and two in the late postoperative period . All patients had thrombocytopenia and prolonged clotting times intraoperatively with evidence of increased thrombin generation ( as demonstrated by elevated PF 1 + 2 ) . Five patients had increased systemic fibrinolysis ( as demonstrated by elevated t-PA activity ) preoperatively and /or before aortic declamping and all of these patients died . Three patients had perioperative inhibition of systemic fibrinolysis ( as demonstrated by elevated PAI activity ) and two survived . These data demonstrate that coagulopathy in ruptured AAA repair may be associated with a hyperfibrinolytic state . Further research is required to determine if ( a ) a causal relationship exists between hyperfibrinolysis and coagulopathy and ( b ) whether antifibrinolytic agents can improve outcome if targeted at this group of patients


Title 3:
Myocardial injury and systemic fibrinolysis in patients undergoing repair of ruptured abdominal aortic aneurysm: a preliminary report.
Abstract 3:
BACKGROUND ruptured abdominal aortic aneurysm ( AAA ) is associated with inhibition of systemic fibrinolysis . Hypofibrinolysis is a risk factor for ischaemic myocardial injury , one of the commonest complications of ruptured AAA repair . Cardiac troponin I ( cTnI ) is one of the most sensitive and specific marker of myocardial injury currently available . OBJECTIVE To examine , for the first time , the relationship between fibrinolytic activity and myocardial injury in patients operated for ruptured AAA . METHODS Twenty patients ( 18 men and 2 women of median age 74 , range 65 - 86 years ) undergoing repair of ruptured AAA were prospect ively studied .  Plasma tissue plasminogen activator ( t-PA ) and plasminogen activator inhibitor ( PAI-1 ) activity were measured pre-operatively , immediately before and five minutes following aortic clamp release . Serum cTnI  was measured pre-operatively , 6 and 24 h following clamp release . Results cTnI was detectable at one or more sample points in 13 ( 65 % ) patients , and in 7 out of 8 patients who suffered major cardiac complications . There was a significant negative correlation between pre-operative t-PA activity and cTnI before operation ( r = -0.55 , p = 0.01 ) and 6 h ( r = -0.51 , p = 0.02 ) after clamp release . There was a significant positive correlation between pre-operative PAI activity and cTnI before operation ( r = + 0.50 , p = 0.03 ) , 6 h ( r = + 0.47 , p = 0.04 ) and 24 h ( r = + 0.50 , p = 0.03 ) after clamp release . There was no correlation between pre- and intra-operative hypotension or blood transfusion requirement and cTnI release . CONCLUSIONS Hypofibrinolysis during ruptured AAA repair is associated with the development of peri-operative myocardial injury . The causal mechanisms underlying this state are not clear but treatment of this prothrombotic/hypofibrinolytic diathesis may help to limit myocardial cell necrosis


Title 4:
Functional outcome after open repair of ruptured abdominal aortic aneurysm.
Abstract 4:
BACKGROUND Outcome after  operative repair of ruptured abdominal aortic aneurysm ( AAA ) has traditionally been assessed in terms of survival . This study examines the functional outcome of patients who survive operation . METHODS Consecutive patients who survived open repair over an 18-month period were entered into a prospect i ve case-control study . Age- and sex-matched controls were identified from patients undergoing elective AAA repair .  The Short Form-36 health survey was administered to both groups of patients at 6 months after operation . Results were compared with the expected scores for an age- and sex-matched normal UK population . RESULTS Fifty-seven patients underwent open repair of a ruptured AAA , and 30 survived ; no patient was lost to follow-up . There were no significant differences in quality of life between patients who had an emergency repair and those who had an elective repair . Both of these groups had poorer health-related quality of life outcomes than the matched normal population . Surprisingly , compared with the normal population , patients after elective repair had poorer outcomes in more health domains than patients who survived emergency operation . CONCLUSIONS Survivors of ruptured AAA repair have a good functional outcome within 6 months of operation


Title 5:
Intraoperative heparinisation, blood loss and myocardial infarction during aortic aneurysm surgery: a Joint Vascular Research Group study.
Abstract 5:
OBJECTIVES The primary aim of this prospect i ve multi-centre study involving patients undergoing elective abdominal aortic aneurysm ( AAA ) surgery was to investigate the relationship between intraoperative intravenous heparinisation , blood loss during surgery and thrombotic complications . METHODS Two hundred and eighty-four patients were r and omised to receive intravenous heparin ( n = 145 ) or no heparin ( n = 139 ) . Groups were evenly matched for age , sex , weight , aneurysm size , haemoglobin concentration , platelet counts and distal occlusive disease measured by ankle/brachial systolic pressure . RESULTS There were no statistically significant differences in blood loss ( median 1400 ml vs. 1500 ml ; z = 0.02 , p = 0.98 , 95 % C.I. = -200 to 200 ) , blood transfused ( 4.0 units vs. 4.0 units ; z = 1.09 , p = 0.28 , 95 % C.I. = -1 to 0 ) or distal thrombosis between the two groups . However , analysis of the clinical outcome revealed that 5.7 % of the non-heparin group but only 1.4 % of the heparinised patients suffered a fatal perioperative myocardial infa rct ion ( MI ) ; p < 0.05 . All MI , including non fatal events , affected 8.5 % and 2 % respectively ( p = 0.02 ) . CONCLUSIONS Heparin does not increase blood loss or the need for blood transfusion during surgery . Heparin is not necessary to prevent distal thrombosis when the aorta is cross clamped . The results of the study are consistent with the known mechanisms leading to intraoperative MI and strategies for its prevention . Intravenous heparin , given before aortic cross clamping , is an important prophylaxic against perioperative MI in relation to AAA surgery


Title 6:
Compensated activation of coagulation in patients with abdominal aortic aneurysm: effects of heparin treatment prior to elective surgery.
Abstract 6:
Elective surgery of abdominal aortic aneurysm ( AAA ) sometimes leads to excessive bleeding and disseminated intravascular coagulation ( DIC ) , even in patients with normal preoperative coagulation parameters . Coagulation screen , performed routinely before surgery is of limited value in the assessment of compensated activation of the haemostatic system . In this study , we used a number of additional tests ( D-dimer , prothrombin fragment 1 + 2 , antithrombin , and activation of fibrinolysis in the platelet poor plasma ) for the diagnosis of compensated activation of the haemostatic system in AAA- patients .  D-dimer and marker of thrombin generation ( prothrombin fragment 1 + 2 ) positively correlated with each other ( r = 0.768 , P < 0.001 ) . Out of 71 AAA patients , 15 patients had normal  global coagulation times  , but those with a D- dimer concentration above 3000 ng/ml were selected for preoperative low molecular weight heparin ( LMWH ) treatment . Administration of LMWH diminished coagulation abnormalities ( D-dimer and prothrombin fragment 1 + 2 decreased significantly ) and result ed in the increase of platelet number and fibrinogen concentration , indicating their previous consumption . Despite differences in aneurysm diameters between the groups of 15 LMWH treated patients ( mean 70.9 + /- 16 mm ) and the reference group of 20 untreated AAA patients ( mean 52.3 + /- 8.0 mm ) , intraoperative parameters ( operation time , blood loss and transfusion dem and s ) were similar


Title 7:
Systemic Administration of Heparin Intraoperatively in Patients Undergoing Open Repair of Leaking Abdominal Aortic Aneurysm May Be Beneficial and Does Not Cause Problems
Abstract 7:
The aim of this study was to investigate whether intravenous heparin administration was associated with a reduction in perioperative mortality and late distal thrombectomy in patients with ruptured abdominal aortic aneuryms ( AAAs ) . One hundred thirty-one patients had repair of ruptured AAA between January 1999 and January 2004 . Sixty-three received heparin according to the consultant 's preference at the time of the operation . Data were prospect ively collected , and multivariate analysis was performed for independent predictive factors . Thirty-day mortality was 29 % . Patients receiving  heparin had lower perioperative mortality ( 16 % vs 42 % ; p = .001 ) . Heparin administration was not associated with increased hemorrhage or transfusion . Multivariate analysis confirmed that heparin administration was independently predictive of survival ( p = .036 ) . Other factors found to reduce survival were age ( p = .023 ) , smoking ( p = .042 ) , and systolic blood pressure ( < 100 mmHg ) at presentation ( p = .045 ) . Fewer patients had thrombectomy after heparin ( 8 % vs 12 % ) , but this was not statistically significant . Perioperative complications were similar in both groups . The administration of systemic heparin before the clamp is applied to leaking aneurysms does not appear to increase hemorrhage and subsequent mortality and may reduce the need for early thrombectomy


Title 8:
Low molecular weight heparin treatment decreases MMP-9 plasma activity in patients with abdominal aortic aneurysm.
Abstract 8:
Large abdominal aortic aneurysms ( AAAs ) are associated with coagulation abnormalities , which are significantly reduced by low molecular weight heparin ( LMWH ) . Considering anti-inflammatory properties of heparin we verified , whether LMWH influences MMP-2/-9 in AAA patients . The study involved 26 AAA individuals , 10 patients with coagulation abnormalities received LMWH and 16 were a control group .  The plasma activity of MMP-2/-9 was measured using zymography . We found that , in addition to the reduction of coagulation abnormalities , LMWH treatment was associated with the decreased MMP-9 but not MMP-2 activity . Therefore , LMWH use could be considered as a valuable pretreatment before an elective aneurysm repair
Therefore , we were unable to assess the effect of intravenous heparin on all-cause mortality and incidence of general arterial disease , for example , cardiovascular , cerebral , pulmonary and renal pathologies in rAAA management in people undergoing an emergency repair .