Anticoagulation in cerebral ischemia.

Abstract

SUMMARYAnticoagulation clearly benefits patients at risk of stroke from cerebral embolism. Con versely, patients with completed ischemic stroke are not benefited, and may show a higher mortality and morbidity because of hemorrhagic complications. Technical advances in the early, accurate diagnosis of cerebral hemorrhage, the constant infusion of heparin, and closer monitoring of anticoagulation have continued to reduce the risk of hemorrhage in treated patients, In patients with TIA, alternative therapy with anti-platelet agents, which appears to prevent stroke at less bleeding risk, is under study. Current results show no differences between the two therapies, but only historical controls are available for evalua tion of benefit. Whether or not anticoagulation prevents progression of neurologic deficit in patients with strokes-in-evolution remains an unanswered question, which can be resolved only by prospective, random ized, controlled trials. analysis of the available literature led to the conclusion that data from randomized prospective trials of anti coagulant use in cerebral ischemia were few, that pa tient numbers were small, and that efficacy of anticoa gulants was either not proven or not deducible, particularly because of inadequate control populations.The current review will demonstrate that although new methods of diagnosis and treatment, and new means of monitoring treatment have been developed, definitive clinical studies have yet to be performed. Therefore, improved methods for differentiating ischemic infarc tion from intracranial hemorrhage, for the administra tion of heparin by infusion rather than bolus injection, for the control of hypertension, and for the monitoring of anticoagulant effect which have become available in the routine care of patients with cerebral ischemia, postdate most of the published major studies of anti coagulation for cerebral ischemia, and need to be in corporated into new trials.While it is generally agreed that thrombosis is an important cause of cerebral ischemia, the thrombotic Hemostatic Function in Patients with Cerebral IshemiaIt is difficult to document hypercoagulability in pa tients with cerebrovascular disease; that is, to fine} signs predictive of a high risk for thrombosis, particu larly imminent thrombosis. 3Plasma coagulatipn fac tors are normally present far in excess of the amounts required for normal blood clotting; elevation of these factors is, therefore, a non-specific finding. On the other hand, activated coagulation factors -evidence of intravascular coagulation -are cleared so rapidly from plasma that their elevation cannot be detected. Moreover, several coagulation factors such as fibrino gen and Factor VIII (anti hemophilic factor) which may be elevated in patients with atherosclerosis, are acute phase reactants whose levels rise with any in flammatory condition such as vasculitis, infection or tissue damage induced by stroke.Platelet hyperactivity is measured by augmented ag gregation or by increased plasma levels of platelet re lease produ...

Transluminal angioplasty for arteriosclerotic disease of the distal vertebral and basilar arteries.

“…Percutaneous transluminal angioplasty was performed in 12 patients with angiographically documented stenosis involving either the distal vertebral artery at the C 1-C2 segment or basilar artery region and who satisfied the following criteria: (1) they were clinically symptomatic with vertebrobasilar ischaemic symptoms or small infarction involving the posterior circulation; (2) they had a haemodynamically significant, angiographically documented stenosis of greater than 70% due to atherosclerosis; and (3) they were refractory to standard medical treatment including antiplatelet therapy, anticoagulation therapy, or both. In patients who had transient ischaemic attacks in the vertebrobasilar distribution, aspirin (325 mg/day) or ticlopidine (200 mg/day) was given for antiplatelet therapy for at least two to three months before all procedures and continued for six months after angioplasty.…”

Decreased incidence and mortality of stroke.

“…The treatment of cardiac emboli may in itself influence favourably the mortality and morbidity of stroke. 8 Increased recognition and treatment of arrhythmias, capable of producing stroke, non-arteriosclerotic heart disease and decreased neurological complications from open heart surgery and prosthetic heart valves 9 may be having a modest but mounting influence on the decline of stroke.…”

Usefulness of Heparin in Initial Management of Patients With Recent Transient Ischemic Attacks

“…During the treatment period that averaged 5.87 days (range, 14 hours to 15 days), 58 (77%) of the 74 patients experienced no new ischemie events, 12 (16.2%) had recurrent TIAs, and five (6.8%) had major cerebral infarc¬ tion. The cerebral infarction was fatal in one patient, and another had a TIA followed by cerebral infarction during the treatment period.…”