Letter by Rudolph Regarding Article, “Reduced Fetal Cerebral Oxygen Consumption Is Associated With Smaller Brain Size in Fetuses With Congenital Heart Disease”
To the Editor:
In the article “Reduced Fetal Cerebral Oxygen Consumption Is Associated With Smaller Brain Size in Fetuses With Congenital Heart Disease” by Sun et al,1 the authors state: “This study supports a direct link between reduced cerebral oxygenation and impaired brain growth in fetuses with CHD and raises the possibility that in utero brain development could be improved with maternal oxygen therapy.”
I have a serious concern that this could lead to widespread introduction of chronic administration of oxygen to pregnant women whose fetuses have been diagnosed with a congenital cardiovascular malformation.
The authors’ conclusion is based on their finding that, in a group of human fetuses with varied congenital cardiovascular malformations, both brain size and cerebral oxygen consumption are reduced in comparison with a group of healthy fetuses. They have chosen to express cerebral oxygen consumption in relation to fetal body weight (milliliters per minute per kilogram) in Table 3 or to body surface area (milliliters per minute per square meter) in Figure 5. Because brain size is smaller in the group with congenital heart disease, although total body weight is similar in the 2 groups, it is not surprising that oxygen consumption by the brain would be reduced. Thus, it is quite possible that the reduced brain size could be the result of some other disturbance and the reduced size could account for the reduced oxygen consumption.
The oxygen delivery to the brain was not significantly different in the fetuses with congenital heart disease in comparison with the healthy fetuses. Thus, oxygen is available if required. Therefore, there does not appear to be an indication for administering oxygen to the mother in an attempt to further increase oxygen delivery to the brain.
A second issue I would like to raise is that fetuses with cardiovascular malformations that result in vastly different hemodynamic disturbances have all been grouped together as having congenital heart disease. It is quite apparent in Table 3 of the article that there are major differences in the groups of fetuses with different types of cardiovascular malformation. Based on the suggestion that maternal oxygen therapy be considered for fetuses with congenital heart disease, this could be applied irrespective of the type of cardiovascular malformation.
I strongly recommend that the time has come for us to consider specific cardiovascular malformations when recommending therapeutic approaches.
Abraham M. Rudolph, MD
University of California San Francisco
San Francisco, CA
- © 2015 American Heart Association, Inc.
- Sun L,
- Macgowan CK,
- Sled JG,
- Yoo SJ,
- Manlhiot C,
- Porayette P,
- Grosse-Wortmann L,
- Jaeggi E,
- McCrindle BW,
- Kingdom J,
- Hickey E,
- Miller S,
- Seed M.