Microvascular Blood Flow in Sickle Cell Anemia

Study Overview
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Brief Summary
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Sickle cell disease (SCD) is an inherited blood disorder that causes the red blood cells to change their shape from a round shape to a half-moon/crescent or sickled shape. Sickle-shaped cells can cause problems by getting stuck in blood vessels, blocking blood flow, and can cause inflammation and injury to important body parts. There are no specific treatments that improve this condition and promote blood flow hindered by sickle cell blockages. Another big challenge in managing sickle cell disease is that there are no good measures to determine changes and improvements in blood flow. Contrast-enhanced ultrasound is a technique currently used to detect blood flow in the heart, muscles, and other organs. It is extremely sensitive and can detect blood flow in the smallest of blood vessels. It would be very useful in helping healthcare providers know whether treatment strategies are improving blood flow during sickle cell blockages. The hypothesis is that contrast-enhanced ultrasound will be a feasible tool for determining changes in blood flow of subjects with sickle cell disease.

Detailed Description
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Sickle cell disease is an inherited blood disorder that affects one of every 400 African-Americans newborns in the United States. Sickle cell disease causes the red blood cells to change their shape from a round shape to a half-moon sickle shape. Individuals who have sickle cell disease have a different type of protein that carries oxygen in the blood (hemoglobin) than individuals without sickle cell disease. This different type of hemoglobin makes the red blood cell change into a crescent shape under certain conditions. Sickle shaped cells are a problem because the often get stuck on blood vessels blocking the flow of blood, and cause inflammation and injury to important areas of the body. These symptoms can lead to a painful occurrence called a sickle cell crisis. Many individuals have to be admitted into the hospital because of the pain caused by a sickle cell crisis. Regadenoson is a drug that may help prevent inflammation and injury caused by the sickle shaped cells. This drug is approved by the FDA to be used as a bolus during a heart stress test in people unable to exercise enough to put stress on the heart by making it beat faster. In a recent Phase I study, a safe dose for regadenoson was determined for adults with sickle cell disease. This dose was given by a slow IV infusion for a 24-48 hour period. Hydroxyurea is the only FDA approved drug for the treatment of sickle cell disease. Hydroxyurea is a pill taken orally and works well but is not useful during a severe sickle cell crisis. In this study researchers will use a new method, contrast-enhanced ultrasound (CEU), to visualize tiny blood vessels in cardiac and skeletal muscle. Changes in CEU measurements before, during and after administration of regadenoson will be examined. Contrast-enhanced ultrasounds will also be performed in individuals who are not having a sickle cell crisis. Some of those individuals will also undergo CEU while they are having a sickle cell crisis to compare those measurements . Lastly CEU results will be compared between individuals with sickle cell anemia and healthy African-Americans. These CEU's will be used to determine if there are changes in the blood flow of tiny blood vessels in certain conditions. This study wants to know if this new method of contrast-enhanced ultrasound will be a useful tool for physicians to use in individuals with sickle cell anemia. The researchers also want to determine if this new method of CEU can be used to reveal if some treatments for sickle cell anemia work better than others.

Official Title
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Effect of Adenosine 2A Receptor Agonist Regadenoson on Microvascular Blood Flow in Sickle Cell Anemia

Conditions
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Sickle Cell Disease, Sickle Cell Anemia

Intervention / Treatment
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* Drug: regadenoson infusion with contrast-enhanced ultrasound
* Procedure: contrast-enhanced ultrasound
* Procedure: contrast-enhanced ultrasound
* Procedure: contrast-enhanced ultrasound
* Procedure: contrast-enhanced ultrasound


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Regadenoson ARM Inclusion Criteria: Diagnosis of sickle cell anemia confirmed by hemoglobin analysis Ages 18 to 70 years Subjects must have laboratory indices as outlined by the protocol Reliable IV access as determined by physician Sickle Cell Controls ARM Inclusion Criteria: Diagnosis of sickle cell anemia confirmed by hemoglobin analysis Ages 18 to 70 years Sickle Cell CEU ARM Inclusion Criteria: Diagnosis of sickle cell anemia, confirmed by hemoglobin analysis Males and females age 18-70 years Healthy Control ARM Inclusion Criteria: African American Ages 18 to 70 years Technique Optimization Control ARM Inclusion Criteria: -Ages 18 to 70 years Exclusion Criteria: Regadenoson ARM Exclusion Criteria Hospitalization, emergency department visit or self-reported crisis within last 2 weeks for any reason or 4 weeks from acute chest syndrome Current physician diagnosis of active asthma (within last 12 months) or current use of asthma medications Second or third degree AV block or sinus node dysfunction Known or suspected right to left sided cardiac shunts History of a bleeding diathesis History of clinically overt stroke History of severe hypertension not adequately controlled with anti-hypertensive medications Receiving chronic anti-coagulation or anti-platelet therapy History of metastatic cancer Receiving other investigational study agents, or have received a study agent in the last 30 days Uncontrolled intercurrent illness Pregnant or breastfeeding women Subjects who have a HIV infection Subjects who have had a hematopoietic stem cell transplant Subjects who are taking medications that may interact with the investigational agent Prior hypersensitivity reactions to either regadenoson or ultrasound contrast agents Sickle Cell Controls Exclusion Criteria: Hospitalization, emergency department visit or self-reported crisis within last 2 weeks for any reason or 4 weeks from acute chest syndrome Known pregnancy Known history of HIV Known or suspected right to left sided cardiac shunts Receiving other investigational study agents, or have received a study agent within the last 30 days Subjects who have had a hematopoietic stem cell transplant Prior hypersensitivity reactions to ultrasound contrast agents History of severe hypertension not adequately controlled with anti-hypertensive medications Uncontrolled intercurrent illness Sickle Cell CEU ARM Exclusion Criteria: Pregnant women Subjects who have a HIV infection History of stem cell transplant Current involvement in a therapeutic clinical trial Known or suspected right to left sided cardiac shunts Prior hypersensitivity reactions to ultrasound contrast agents History of severe hypertension not adequately controlled with anti-hypertensive medications Uncontrolled intercurrent illness Healthy Control ARM Exclusion Criteria: Sickle cell disease or sickle cell trait Known or suspected right to left sided cardiac shunts Diagnosis of type 1 or type 2 diabetes mellitus Hypertension History or current diagnosis of dyslipidemia or taking lipid lowering drugs Diagnosis of coronary artery disease or peripheral vascular disease Body weight greater than 10% of ideal weight Uncontrolled intercurrent illness Pregnant or breastfeeding women Subjects who have a HIV infection Prior hypersensitivity reactions to ultrasound contrast agents Technique Optimization Control ARM Exclusion Criteria: Known sickle cell disease or sickle cell trait Known or suspected right to left sided cardiac shunts Uncontrolled intercurrent illness Known pregnant or breastfeeding women Prior hypersensitivity reactions to ultrasound contrast agents

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Regadenoson ARM<br>Adult subjects with sickle cell anemia will receive a regadenoson infusion with contrast-enhanced ultrasound | Drug: regadenoson infusion with contrast-enhanced ultrasound<br>* Subjects who are not having a pain crisis receive a 24-hour infusion of regadenoson. Contrast-enhanced ultrasound will be performed four times during the 24 hour regadenoson infusion<br>* Other names: regadenoson;|
| Other: Sickle Cell Controls ARM<br>Adult subjects with sickle cell anemia will receive contrast-enhanced ultrasound | Procedure: contrast-enhanced ultrasound<br>* Subjects who are not having a pain crisis will have contrast-enhanced ultrasound performed up to four times over a two-day period. Time points will resemble the time course used for the Regadenoson Arm, although no investigational drug will be given.<br>|
| Other: Sickle Cell CEU ARM<br>Adults subjects with sickle cell anemia will receive contrast-enhanced ultrasound | Procedure: contrast-enhanced ultrasound<br>* Contrast-enhanced ultrasound will be performed on adults with sickle cell anemia at baseline who are not having a pain crisis and performed again during a pain crisis<br>|
| Other: Healthy Control ARM<br>Healthy African American control subjects without sickle cell anemia will receive contrast-enhanced ultrasound | Procedure: contrast-enhanced ultrasound<br>* Contrast-enhanced ultrasound will be performed on healthy control subjects at baseline, on the first day of the study and 30 days later<br>|
| Other: Technique Optimization Controls<br>Healthy volunteers will undergo contrast-enhanced ultrasound. | Procedure: contrast-enhanced ultrasound<br>* Contrast-enhanced ultrasound will be performed on healthy volunteers (Technique Optimization Controls)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microvascular Blood Flow in Sickle Cell Anemia with Regadenoson Use | To determine changes in microvascular blood flow using contrast-enhanced ultrasound in adults with sickle cell anemia before, during and after a 24 hour infusion of regadenoson | 5 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in Microvascular Blood Flow in Subjects with Sickle Cell Anemia During a Pain Crisis | To examine differences in microvascular blood flow using contrast-enhanced ultrasound in adults with sickle cell anemia at a baseline state, and also comparing to contrast-enhanced ultrasound measurements during a pain crisis | 5 years | 
| Microvascular Blood Flow in Sickle Cell Anemia Subjects Versus Control Subjects | Examine microvascular blood flow using contrast-enhanced ultrasounds in adult subjects with sickle cell anemia compared to microvascular blood flow of healthy African-American adults | 5 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sickle cell, sickle cell crisis, sickle cell pain crisis, vaso-occlusive crisis, vaso-occlusion, sickle cell anemia, sickle cell disease, genetic diseases, adenosine 2A Receptor Agonists, Lexiscan, Regadenoson, contrast-enhanced ultrasound, Hydroxyurea