indium-oxine and Ischemic-Attack--Transient

Topics: Aged; Aortic Aneurysm; Blood Platelets; Blood Vessel Prosthesis; Cell Survival; Cerebrovascular Disorders; Heart Diseases; Humans; Indium; Ischemic Attack, Transient; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Pulmonary Embolism; Radioisotopes; Radionuclide Imaging; Thrombocytopenia; Thromboembolism; Thrombophlebitis; Time Factors

Platelet half-life was assessed with autologous 111In-marked platelets in fourteen subjects, four women and ten men, who previously had suffered vascular accidents (myocardial infarction, TIA, stroke or peripheral obstructive arterial disease). Results, compared to findings in low risk subjects showed a statistically significant correlation of platelet half-life to certain pathologies (TIA, stroke) as well as to habits (tobacco, alcohol) and biological variables (age, sex). By and large, data were analogous to those of the current scientific literature in so far as certain factors shorten platelet half-life. A correlation was also found between platelet half-life and time elapsed since the pathological event. Liver sequestration evaluated by total body scintigraphy showed high levels in one case each with a history of stroke, a history of TIA, and a history of peripheral arterial disease, and splenic sequestration in only one case with a history of stroke.

Topics: Adult; Aged; Blood Platelets; Cell Survival; Cerebrovascular Disorders; Coronary Disease; Female; Humans; Indium Radioisotopes; Ischemia; Ischemic Attack, Transient; Male; Middle Aged; Models, Biological; Organometallic Compounds; Oxyquinoline; Peripheral Vascular Diseases

To investigate the pathophysiological process of transient ischaemic events in a clinically relevant model, we produced transient focal cerebral ischaemia in five baboons using endogenously generated platelet microemboli. Thrombogenic segments of Dacron vascular graft were incorporated as unilateral carotid arterio-arterial shunts to produce endogenous platelet microemboli. The embolized microparticles were quantified by isotopic imaging using 111In-platelets and by transcranial Doppler ultrasonography. Platelet microemboli accumulated rapidly in the shunted carotid territory and reached a maximum value of 3.2 +/- 0.8 x 10(9) in the embolized hemisphere 20 min after initiating blood flow through the graft segment. Sixty min after removing the grafts 111In-platelets were largely cleared from hemispheric vasculature. Recovered animals exhibited mild contralateral hemiparesis which disappeared completely within 24 h. We conclude that endogenously generated platelet microemboli accumulate transiently in the dependent cerebral circulation and produce corresponding transient focal neurological dysfunction. This model may be useful in the evaluation of new therapeutic strategies in acute stroke.

Topics: Animals; Brain; Cerebrovascular Circulation; Echoencephalography; Indium Radioisotopes; Ischemic Attack, Transient; Male; Organometallic Compounds; Oxyquinoline; Papio; Platelet Count; Thromboembolism; Tomography, Emission-Computed

A new dual isotope scintigraphic (DISC) examination of the carotid arteries consisting of simultaneous injections of 111In-labeled platelets and 99mTc-labeled red cells was performed on eight male patients suffering from amaurosis fugax attacks. In concordance with the angiographically proven high percentage of significant extracranial carotid disease in patients with amaurosis fugax, six of the eight patients examined had an increased platelet accumulation in the carotid artery clinically affected. In one patient with normal angiography and one amaurosis fugax attack the platelet scintigraphy even revealed a pathological platelet accumulation in the ipsilateral carotid artery. These findings confirm the hypothesis that most amaurosis fugax attacks are due to arterio-arterial emboli originating from atherosclerotic plaques of the carotid bifurcation.

Topics: Aged; Arteriosclerosis; Blindness; Carotid Artery Diseases; Carotid Artery Thrombosis; Carotid Artery, External; Carotid Artery, Internal; Cerebral Angiography; Constriction, Pathologic; Humans; Indium; Ischemic Attack, Transient; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Radionuclide Imaging; Serum Albumin; Technetium Tc 99m Aggregated Albumin; Tin; Tin Compounds

Topics: Adult; Aged; Blood Platelets; Carotid Artery Thrombosis; Cerebral Infarction; Erythrocytes; Female; Humans; Indium; Ischemic Attack, Transient; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Radioisotopes; Radionuclide Imaging; Serum Albumin; Technetium Tc 99m Aggregated Albumin; Tin; Tin Compounds