Recent data shows that more than 500,000 women in the U.S. report drinking during pregnancy, with about 20 percent of this population admitting to binge drinking. Even one episode of heavy drinking can lead to the collection of birth defects known as fetal alcohol syndrome (FAS). Along with growth retardation, head and face abnormalities, and neurological problems, FAS also causes heart problems in just over half of those with this condition. Though much research has focused on looking for the cause of these alcohol-induced heart defects, they remain largely a mystery.
To investigate this question, Ganga Karunamuni of Case Western University and her colleagues studied heart formation in quail embryos, whose heart development is very similar to that of humans. The researchers used an innovative imaging technique, optical coherence tomography, to compare embryos exposed to a single, large dose of alcohol to those who hadn't received alcohol. They looked both at how alcohol changed the function of the developing hearts as well as their structure. They found that significant changes in heart function appeared to come well before changes in structure that are hallmarks of the well-known FAS heart anomalies. These changes in function, the study authors suggest, might be the cause of the structural problems that arise later by exerting forces on the heart that change its development.
The article is entitled "Ethanol Exposure Alters Early Cardiac Function in the Looping Heart: A Mechanism for Congenital Heart Defects?" It appears in the Articles in Press section of the American Journal of Physiology – Heart and Circulatory Physiology, published by the American Physiological Society.
Methodology
The researchers studied three sets of quail embryos. In one set of these embryos, the researchers injected a quantity of alcohol into their shells proportional to the amount that would be considered a single episode of binge drinking in a pregnant woman. They purposely chose a time during early development in which embryos are especially vulnerable to the effects of alcohol. In another set of embryos, the researchers injected their shells with saline, a placebo not known to have any harmful effects. The researchers left a third set of embryos to develop without any interventions.
Using an imaging modality called optical coherence tomography, which gives the ability to peer through layers of tissue, the researchers kept an eye on the developing hearts at a particular stage when the primitive heart switches from a tube shape to a loop-shaped circuit. The researchers compared both heart blood flow and anatomy at this stage between the three different sets of embryos. They also compared heart anatomy between the different sets both at this looping stage and at a stage closer to hatching.
Results
As expected, the researchers found that the hearts of embryos exposed to alcohol had dramatic defects close to hatching, including thinner walls separating the heart's four chambers and damaged valves. Long before these defects formed, the researchers saw significant differences in heart blood flow between embryos that weren't exposed to alcohol and those that were. In those whose shells weren't injected with alcohol, a small portion of the blood flowed backward through the heart circuit after each beat. In those exposed to alcohol, a much larger portion of blood flowed backward in the circuit. These malfunctioning hearts had smaller "cardiac cushions"—collections of cells that later become chamber walls and valves—compared to unexposed hearts.
Importance of the Findings
The authors suggest that this improper function may itself steer developing hearts in the wrong direction during development, setting the stage for larger defects to arise. Previous studies have shown that because cells in the heart and elsewhere are responsive to mechanical forces, those forces exerted by blood flow can affect heart formation. By learning more about these functional changes in the early heart, the researchers suggest that it may eventually be possible to redirect blood flow to a more healthful pattern, thereby rescuing FAS hearts before they form defects.
"With an average of 4 million U.S. pregnancies per year, there will be approximately 10,000 cases of alcohol-induced congenital heart defects," the study authors write. "Continued study of the mechanisms involved in the development of alcohol-induced cardiac birth defects is warranted in order to implement effective treatments and/or prevention strategies."
Explore further: Environmental toxins linked to heart defects
More information: ajpheart.physiology.org/content/early/2013/11/20/ajpheart.00600.2013
Medical Xpress on facebook
Related Stories
First-ever 3-D stress map of developing embryonic heart sheds light on why defects form
Oct 31, 2012
As a human fetus develops, its heart has to keep pace with the new body's ever-growing demands. Much of this is controlled by following genetic blueprints, but the embryonic heart also matures in response ...
Folate prevents alcohol-induced congenital heart defects in mice
May 24, 2010
A new animal study has found that high levels of the B-vitamin folate (folic acid) prevented heart birth defects induced by alcohol exposure in early pregnancy, a condition known as fetal alcohol syndrome.
Environmental toxins linked to heart defects
Nov 17, 2013
Children's congenital heart defects may be associated with their mothers' exposure to specific mixtures of environmental toxins during pregnancy, according to research presented at the American Heart Association's Scientific ...
Congenital heart defects could have their origin during very early pregnancy
Dec 13, 2012
The origins of congenital heart defects could be traced right back to the first stages of embryonic development, according to University of East Anglia (UEA) research.
Finding triggers of birth defects in an embryo heart
Oct 30, 2012
Researchers at Case Western Reserve University have found a way to create three-dimensional maps of the stress that circulating blood places on the developing heart in an animal model – a key to understanding triggers of ...
Recommended for you
Researchers say fructose does not impact emerging indicator for cardiovascular disease
57 seconds ago
Fructose, the sugar often blamed for the obesity epidemic, does not itself have any impact on an emerging marker for the risk of cardiovascular disease known as postprandial triglycerides, new research has found.
Too few Americans aware of their high blood pressure
Dec 24, 2013
(HealthDay)—High blood pressure is a preventable and treatable risk factor for heart attack and stroke, but about one-quarter of adults don't know they have it, according to a large new study.
California family celebrates three heart transplants
Dec 24, 2013
Deanna Kremis remembers the exhilarating day her young sons first had the energy to race each other up a flight of stairs.
Study finds black women most likely to have high blood pressure
Dec 23, 2013
(HealthDay)—Black women in the United States are much more likely to have high blood pressure than black men or white women and men, according to a new study.
Bah humbug: Heart woes can spike this time of year
Dec 23, 2013
'Tis the season—for heart attacks? Not to dampen any spirits, but studies show heart troubles spike this time of year.
Fewer than one in ten Canadians in ideal cardiovascular health
Dec 23, 2013
Fewer than 1 in 10 adult Canadians is in ideal cardiovascular health, according to the new CANHEART health index developed to measure heart health published in CMAJ (Canadian Medical Association Journal).
User comments
© Medical Xpress 2011-2013, Science X network
Recent data shows that more than 500,000 women in the U.S. report drinking during pregnancy, with about 20 percent of this population admitting to binge drinking. Even one episode of heavy drinking can lead to the collection of birth defects known as fetal alcohol syndrome (FAS). Along with growth retardation, head and face abnormalities, and neurological problems, FAS also causes heart problems in just over half of those with this condition. Though much research has focused on looking for the cause of these alcohol-induced heart defects, they remain largely a mystery.
To investigate this question, Ganga Karunamuni of Case Western University and her colleagues studied heart formation in quail embryos, whose heart development is very similar to that of humans. The researchers used an innovative imaging technique, optical coherence tomography, to compare embryos exposed to a single, large dose of alcohol to those who hadn't received alcohol. They looked both at how alcohol changed the function of the developing hearts as well as their structure. They found that significant changes in heart function appeared to come well before changes in structure that are hallmarks of the well-known FAS heart anomalies. These changes in function, the study authors suggest, might be the cause of the structural problems that arise later by exerting forces on the heart that change its development.
The article is entitled "Ethanol Exposure Alters Early Cardiac Function in the Looping Heart: A Mechanism for Congenital Heart Defects?" It appears in the Articles in Press section of the American Journal of Physiology – Heart and Circulatory Physiology, published by the American Physiological Society.
Methodology
The researchers studied three sets of quail embryos. In one set of these embryos, the researchers injected a quantity of alcohol into their shells proportional to the amount that would be considered a single episode of binge drinking in a pregnant woman. They purposely chose a time during early development in which embryos are especially vulnerable to the effects of alcohol. In another set of embryos, the researchers injected their shells with saline, a placebo not known to have any harmful effects. The researchers left a third set of embryos to develop without any interventions.
Using an imaging modality called optical coherence tomography, which gives the ability to peer through layers of tissue, the researchers kept an eye on the developing hearts at a particular stage when the primitive heart switches from a tube shape to a loop-shaped circuit. The researchers compared both heart blood flow and anatomy at this stage between the three different sets of embryos. They also compared heart anatomy between the different sets both at this looping stage and at a stage closer to hatching.
Results
As expected, the researchers found that the hearts of embryos exposed to alcohol had dramatic defects close to hatching, including thinner walls separating the heart's four chambers and damaged valves. Long before these defects formed, the researchers saw significant differences in heart blood flow between embryos that weren't exposed to alcohol and those that were. In those whose shells weren't injected with alcohol, a small portion of the blood flowed backward through the heart circuit after each beat. In those exposed to alcohol, a much larger portion of blood flowed backward in the circuit. These malfunctioning hearts had smaller "cardiac cushions"—collections of cells that later become chamber walls and valves—compared to unexposed hearts.
Importance of the Findings
The authors suggest that this improper function may itself steer developing hearts in the wrong direction during development, setting the stage for larger defects to arise. Previous studies have shown that because cells in the heart and elsewhere are responsive to mechanical forces, those forces exerted by blood flow can affect heart formation. By learning more about these functional changes in the early heart, the researchers suggest that it may eventually be possible to redirect blood flow to a more healthful pattern, thereby rescuing FAS hearts before they form defects.
"With an average of 4 million U.S. pregnancies per year, there will be approximately 10,000 cases of alcohol-induced congenital heart defects," the study authors write. "Continued study of the mechanisms involved in the development of alcohol-induced cardiac birth defects is warranted in order to implement effective treatments and/or prevention strategies."
Explore further: Environmental toxins linked to heart defects
More information: ajpheart.physiology.org/content/early/2013/11/20/ajpheart.00600.2013
Medical Xpress on facebook
Related Stories
First-ever 3-D stress map of developing embryonic heart sheds light on why defects form
Oct 31, 2012
As a human fetus develops, its heart has to keep pace with the new body's ever-growing demands. Much of this is controlled by following genetic blueprints, but the embryonic heart also matures in response ...
Folate prevents alcohol-induced congenital heart defects in mice
May 24, 2010
A new animal study has found that high levels of the B-vitamin folate (folic acid) prevented heart birth defects induced by alcohol exposure in early pregnancy, a condition known as fetal alcohol syndrome.
Environmental toxins linked to heart defects
Nov 17, 2013
Children's congenital heart defects may be associated with their mothers' exposure to specific mixtures of environmental toxins during pregnancy, according to research presented at the American Heart Association's Scientific ...
Congenital heart defects could have their origin during very early pregnancy
Dec 13, 2012
The origins of congenital heart defects could be traced right back to the first stages of embryonic development, according to University of East Anglia (UEA) research.
Finding triggers of birth defects in an embryo heart
Oct 30, 2012
Researchers at Case Western Reserve University have found a way to create three-dimensional maps of the stress that circulating blood places on the developing heart in an animal model – a key to understanding triggers of ...
Recommended for you
Researchers say fructose does not impact emerging indicator for cardiovascular disease
57 seconds ago
Fructose, the sugar often blamed for the obesity epidemic, does not itself have any impact on an emerging marker for the risk of cardiovascular disease known as postprandial triglycerides, new research has found.
Too few Americans aware of their high blood pressure
Dec 24, 2013
(HealthDay)—High blood pressure is a preventable and treatable risk factor for heart attack and stroke, but about one-quarter of adults don't know they have it, according to a large new study.
California family celebrates three heart transplants
Dec 24, 2013
Deanna Kremis remembers the exhilarating day her young sons first had the energy to race each other up a flight of stairs.
Study finds black women most likely to have high blood pressure
Dec 23, 2013
(HealthDay)—Black women in the United States are much more likely to have high blood pressure than black men or white women and men, according to a new study.
Bah humbug: Heart woes can spike this time of year
Dec 23, 2013
'Tis the season—for heart attacks? Not to dampen any spirits, but studies show heart troubles spike this time of year.
Fewer than one in ten Canadians in ideal cardiovascular health
Dec 23, 2013
Fewer than 1 in 10 adult Canadians is in ideal cardiovascular health, according to the new CANHEART health index developed to measure heart health published in CMAJ (Canadian Medical Association Journal).
User comments
© Medical Xpress 2011-2013, Science X network
0 comments:
Post a Comment