Stroke Prevention Trial in Sickle Cell Anemia

Adams, Robert J.; McKie, Virgil; Brambilla, Don; Carl, Elizabeth; Gallagher, Dianne; Nichols, Fenwick T.; Roach, Steve; Abboud, Miguel R.; Berman, Brian; Driscoll, Catherine; Files, Beatrice; Hsu, Lewis L.; Hurlet, A.; Miller, Scott T.; Olivieri, Nancy F.; Pegelow, Charles H.; Scher, Charles D.; Vichinsky, Elliott; Wang, Winfred C.; Woods, Gerald M.; Kutlar, Abdullah; Wright, Elizabeth C.; Hagner, Susan; Tighe, Foss; Lewin, Jonathan S.; Curé, Joel K.; Zimmerman, Robert A.; Waclawiw, Myron A.

doi:10.1016/s0197-2456(97)00099-8

Cited by 234 publications

(168 citation statements)

References 12 publications

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“…by guest www.bloodjournal.org From levels at less than 30%. 92,93 Transfusion has also been shown to greatly reduce the risk of a first stroke in children with SCD who have abnormal results on transcranial Doppler ultrasonography. 94 Thrombotic manifestations were also observed in 2 knockouttransgenic mouse models of SCD.…”

Section: Similarity Of Thromboembolic Manifestations and Hemostatic Cmentioning

confidence: 99%

The hypercoagulable state in thalassemia

Eldor

Rachmilewitz

2002

Blood

432

372

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Thalassemia is a congenital hemolytic disorder caused by a partial or complete deficiency of ␣-or ␤-globin chain synthesis. Homozygous carriers of ␤-globin gene defects suffer from severe anemia and other serious complications from early childhood. The disease is treated by chronic blood transfusion. However, this can cause severe iron overload resulting in progressive organ failure. Some forms of ␣ thalassemia are also associated with a similar clinical picture. Despite the difficulties associated with treatment, standards of care for thalassemic patients have improved in recent years, resulting in almost doubling of the average life expectancy. As a consequence, additional previously undescribed, complications are now being recognized. In particular, profound hemostatic changes have been observed in patients with ␤-thalassemia major (␤-TM) and ␤-thalassemia intermedia (␤-TI) and also in patients with ␣ thalassemia (hemoglobin H disease). The presence of a higher than normal incidence of thromboembolic events, mainly in ␤-TI, and the existence of prothrombotic hemostatic anomalies in the majority of the patients, even from a very young age, have led to the recognition of the existence of a chronic hypercoagulable state in thalassemic patients. Despite the appearance of numerous publications on the frequent occurrence of thromboembolic complications in thalassemia, this complication has not been emphasized or comprehensively reviewed. This review summarizes the current literature and discusses possible mechanisms of the lifelong hypercoagulable state that exists in thalassemia. (Blood. 2002;99:36-43)

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Section: Similarity Of Thromboembolic Manifestations and Hemostatic Cmentioning

confidence: 99%

The hypercoagulable state in thalassemia

Eldor

Rachmilewitz

2002

Blood

432

372

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“…Transfusion, with reduction of hemoglobin S to less than 30% of total hemoglobin, will lower this risk by 70% compared with standard care alone. [5][6][7][8] An optimal timing to re-screen children with sickle cell disease and normal TCD is not set, but a repeat TCD examination every 6 months seems to be a reasonable objective.…”

Section: Sickle Cell Diseasementioning

confidence: 99%

Transcranial Doppler: An Introduction for Primary Care Physicians

Kassab¹,

Majid²,

Farooq³

et al. 2007

The Journal of the American Board of Family Medicine

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Christian Johann Doppler, a mathematician, physician, and astronomer, first described the Doppler principle in 1843. Its use in neurology was first reported in 1982, 1 and since then, its convenience and growing range of uses have made it an attractive tool to evaluate the cerebrovascular tree in patients with neurovascular disorders. Transcranial Doppler (TCD) is a noninvasive ultrasound device that allows real-time evaluation of the intracranial cerebral circulation. It is currently under-utilized in part due to the lack of awareness about the diagnostic usefulness of this test. In this article, we will review TCD testing as a procedure and discuss its clinical applications of special interest to the primary care physician. Examination and Doppler InstrumentUltrasound examination of a vessel by means of TCD is referred to as insonation. The TCD probe is placed over different "acoustic windows" that are specific areas of skull where there is a lack of boney covering or the cranial bone is thin (Figure 1). The transtemporal (temporal) window is used to insonate the middle cerebral artery (MCA), the anterior cerebral artery (ACA), the posterior cerebral artery (PCA), and the terminal portion of the internal carotid artery (TICA), before its bifurcation. The transorbital (orbital) window gives access to insonate the ophthalmic artery (OA) as well as the internal carotid artery at the siphon level. The transforaminal (occipital) window allows insonation of the distal vertebral arteries (VA) and the basilar artery (BA). Finally, the submandibular window allows insonation of the more distal portions of the extracranial internal carotid artery. TCD does not allow direct visualization of insonated vessels like carotid Doplex, rather it is an indirect evaluation by means of an ultrasonic beam of 2 MHz frequency that is produced from piezoelectric crystals that have been stimulated electrically. This beam bounces off the erythrocytes within the insonated artery. The reflected signal is received by the transducer and converted to an electric signal (Figure 2). This information is subtracted from the transmitted signal and then processed to obtain a waveform that allows accurate determination of blood flow velocities, direction of flow, and also allows for certain calculated parameters to be added to the evaluation. The pulsatility index (PI) is one of the useful calculated parameters, and it is considered a reliable marker of resistance distal to the insonated site. It is usually calculated by the Gosling equation. 2 PI ϭ (Peak systolic velocity Ϫ end diastolic velocity)/mean velocity.

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“…The trial design is described in detail elsewhere. 7 Recruitment and TCD screening for STOP occurred from February 1995 to November 1996, and stroke surveillance continued until June 2000.…”

Section: Subjectsmentioning

confidence: 99%

“…Each study center used a TCD standard protocol developed for children with SCD, and examiners were trained for this protocol with identical equipment and software (2-MHz pulsed Doppler; Nicolet EME TC 2000; Nicolet, Madison, WI). 6,7 The TCD examiner moved the sample volume depth in 2-mm increments to record the highest TAMMvel and the clearest waveform profile in these arterial segments: from the right and left temporal approaches, the MCA at 3 or more points along the artery separated by 2 mm; the distal ICA; the anterior cerebral artery (ACA) and posterior cerebral artery (PCA); and the basilar artery from the suboccipital approach. Each TCD was interpreted at the Medical College of Georgia (Augusta, GA) without knowledge of its source and categorized by TAMMvel values as normal (all recordings lower than 170 cm/s); conditional (at least 170 but lower than 200 cm/s); abnormal (TAMMvel of at least 200 cm/s in either the ICA or MCA); or inadequate.…”

Section: Subjectsmentioning

confidence: 99%

Stroke and conversion to high risk in children screened with transcranial Doppler ultrasound during the STOP study

Adams

Brambilla

Granger

et al. 2004

Blood

162

124

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The Stroke Prevention Trial in Sickle Cell Anemia (STOP) was a randomized multicenter controlled trial comparing prophylactic blood transfusion with standard care in sickle cell anemia (SCA) children aged 2 to 16 years selected for high stroke risk by transcranial Doppler (TCD). More than 2000 children were screened with TCD to identify the 130 high-risk children who entered the randomized trial. A total of 5613 TCD studies from 2324 children were evaluated. We also collected information on stroke. We describe the changes in TCD with repeated testing and report the outcome without transfusion in the STOP screened cohort. Risk of stroke was higher with abnormal TCD than with normal or conditional TCD (P < .001) or inadequate TCD (P ‫؍‬ .002), and risk with conditional TCD was higher than with normal TCD (P < .001). Repeated TCD in 1215 children showed that the condition of 9.4% of children became abnormal during observation. Younger patients and those with higher initial flow velocities were most likely to convert to abnormal TCDs. Screening in STOP confirmed the predictive value of TCD for stroke. Substantial differences in the probability of conversion to abnormal TCD were observed, with younger children and those with higher velocity more likely to have an abnormal TCD with rescreening.

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Stroke Prevention Trial in Sickle Cell Anemia

Cited by 234 publications

References 12 publications

The hypercoagulable state in thalassemia

The hypercoagulable state in thalassemia

Transcranial Doppler: An Introduction for Primary Care Physicians

Stroke and conversion to high risk in children screened with transcranial Doppler ultrasound during the STOP study

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