Monitoring the effect of anticoagulants on left atrial thrombi in patients with rheumatic heart disease: assessment with 111In-oxine-labelled platelet heart scintigraphy and transoesophageal echocardiography

Indium-111-oxine-labeled platelet scintigraphic images in the assessment of thrombogenicity in small-caliber prosthetic vascular grafts

Anti-thrombogenicity is one of the essential factors for successful development of small-caliber prosthetic vascular grafts, and its accurate evaluation is important. The purpose of this study was to investigate the efficacy of indium-111-oxine-labeled (In) platelet scintigraphic images in the assessment of graft thrombogenicity. Fibrin-coated knitted polyester vascular prostheses, 2 mm in diameter and 2 cm in length, were implanted in the bilateral common carotid arteries of 18 Japanese white rabbits. The grafts were explanted on postoperative days 1, 3, 7, 10, 14, and 30 (six grafts on each of the days), and In platelet scintigraphy was performed with visual, semiquantitative, and quantitative analysis. The relationships among the three analyses were evaluated. Platelet depositions on the luminal surface were clearly visualized with In-platelet scintigraphy if the number of In platelets was more than 4.8 x 10 counts per minute, even if a macroscopic thrombus formation was not observed. There was a highly significant correlation between the graft region of interest on the images and the total platelet deposition (p<.0001). The images in the thrombotic grafts have shown a very strong In-platelet accumulation, but there were some limitations in the In-platelet scintigraphic images. In-platelet scintigraphic images are useful for evaluating platelet deposition in small-caliber vascular prostheses if they are performed with a proper understanding of their limitations.

Treatable Potential Cardiac Sources of Embolism in Patients with Cerebral Ischemic Events: A Selective Transesophageal Echocardiographic Study

OBJECTIVES

To characterize cardiac sources of emboli detected by transesophageal echocardiography (TEE) in patients without recognizable cause of transient ischemic attack (TIA) and/or ischemic stroke and TIA.

METHODS

We examined a prospective registry that included all patients with TIA and/or stroke evaluated by TEE between July 2000 and August 2001 at our medical center. Ischemic events were classified according to clinical and neuroimaging findings as cortical, lacunar, or vertebrobasilar circulation. Demographic, clinical, neuroimaging, and echocardiographic characteristics were studied.

RESULTS

TEE was performed in 237 patients without recognized cause of TIA and/or stroke, of which 105 (44%) events were cortical, 35 (15%) were lacunar, 32 (14%) were vertebrobasilar, and 65 (27%) were in multiple distributions. Mean age of patients was 59 +/- 14 years (range, 21 to 93 years); 119 (51%) were men. Potential treatable cardioembolic sources were detected in 146 (61%) patients: patent foramen ovale with right-to-left shunt (n = 59), left atrial clot (n = 6), left atrial appendage clot (n = 8), and severe thoracic aortic atherosclerotic plaque disease (plaque thickness >4 mm) (n = 79 patients [33%], 56 had an ulcerated plaque and 4 had mobile plaque). Patient age and topography of the ischemic event did not correlate with TEE-defined cardioembolic sources.

CONCLUSIONS

TEE identified high frequencies of potential treatable cardioembolic sources in patients with ischemic events. TEE should be considered in all patients who do not have identified cause of TIA and/or stroke for early treatment and prevention of recurrent events.