Heart problems are fairly common in young adults with sickle cell disease, but physicians don't fully understand why. The researchers demonstrated that lower oxygen saturation in the blood was linked to the heart structure seen in the 44 children studied.
Sickle cell disease is an inherited blood disorder affecting red blood cells, which contain hemoglobin, the substance that carries oxygen from the lungs to all parts of the body. In patients with this disease, red blood cells contain an abnormal type of hemoglobin that causes the normally round, flexible red blood cells to become stiff and sickle- or crescent-shaped. The sickle cells can't pass through tiny blood vessels, which can prevent blood from reaching some tissues and can result in tissue and organ damage, pain and stroke.
In addition, sickle cells are short lived and lead to a shortage of red blood cells and anemia, which make the heart grow bigger because it has to work harder, says Mark C. Johnson, MD, associate professor of pediatrics at Washington University School of Medicine and first author of the study.
In this study, the first to analyze sleep studies and echocardiograms of children with sickle cell disease, these heart abnormalities were found in the left pumping chamber, or left ventricle, of the children's hearts. The findings included an enlarged left ventricle, called ventricular hypertrophy, and abnormal blood filling of the left ventricle, called diastolic dysfunction. Both are associated with early death in adults with sickle cell disease, but the meanings of the same results in children are unclear.
"This suggests that the beginning of adult heart disease may start in children, but we need to follow these patients longitudinally to strengthen the meaning of the findings," says Michael R. DeBaun, MD, a Washington University sickle cell disease specialist at St. Louis Children's Hospital and senior author of the study, published online in Blood First Edition April 8, 2010.
"Many researchers assumed it was the anemia alone that makes the heart enlarge, but this study suggests it's not that simple," Johnson says.
Researchers began the study thinking that the abnormalities in the left ventricle, the heart's main blood-pumping chamber, would be the result of sleep-disordered breathing, such as sleep apnea, commonly found in children with sickle cell disease. Sleep-disordered breathing has previously been associated with left ventricle hypertrophy and with diastolic dysfunction in children and adults. But only about one-fifth of the children had some evidence of obstructive apnea hypopnea, or recurrent episodes of upper airway collapse and obstruction during sleep.
Researchers also thought they would find lower oxygen saturation while patients were sleeping compared to when they were awake. However, the average oxygen saturation while asleep and awake were similar. Only about one-fourth of patients had average oxygen saturation values below normal.
The echocardiograms showed that 46 percent of participants had left ventricle hypertrophy in which the chamber of the left ventricle was enlarged. The research team's analysis showed that for every 1 percent drop in oxygen saturation, there was a measurable increase in the mass of the heart's left ventricle.
"The average oxygen saturation of 97 percent in these children is in a normal range, but the patients with slightly lower levels had enlarged hearts," Johnson says. "A relatively small change in oxygen levels caused a big change in the heart. That's what makes us think there's something under the surface that we don't quite understand yet."
The team also measured an indicator of pulmonary hypertension, or high blood pressure in the lungs, the major cause of death in adults with sickle cell disease. When the pulmonary hypertension level is raised in adults with sickle cell disease, it is a strong predictor of death within 24 months. However, despite the strong association between pulmonary hypertension and sleep abnormalities, no such association was demonstrated in this study, DeBaun says.
Johnson and DeBaun say more sleep and cardiac studies are needed to confirm the association of left ventricle abnormalities with low blood oxygen levels. In the future, the researchers plan to look at other indicators to find potential new therapies to prevent progression of the disease.
Johnson M, Kirkham F, Redline S, Rosen C, Yan Y, Roberts I, Gruenwald J, Marek J, DeBaun M. Left Ventricular Hypertrophy and Diastolic Dysfunction in Children with Sickle Cell Disease are Related to Asleep and Waking Oxygen Desaturation. Blood First Edition. Prepublished online April 8, 2010.
Funding for this study was provided by the National Heart, Lung, and Blood Institute.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Beth Miller | EurekAlert!
Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg
New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences