April 23, 2014
Critical Congenital Heart Defect Screening - A Simple Newborn Test that Saves Lives
By: Sharon Muza, BS, LCCE, FACCE, CD/BDT(DONA), CLE | 0 Comments
By Elias Kass, ND, CPM, LM
Critical Congenital Heart Defect screening can help identify and save the lives of newborns born with previously undetected but serious malformations of the heart that can significantly impact them as they transition to life on the outside. Families can learn about the simple screening procedure in a childbirth education class and be prepared to discuss the screening with their health care providers. Dr. Elias Kass, naturopath and midwife, shares information on the screening, stats on the incidence of CCHDs and how you can help spread the word on the importance of all newborns being screened. - Sharon Muza, Community Manager, Science & Sensibility
There's a new newborn screening being implemented in many birth settings - critical congenital heart defect screening, or CCHD. What is this screening? What does it look for, and how can you educate and prepare your childbirth education students for the screening and possible results?
Critical congenital heart defects refer to heart defects that babies are born with and that require surgical intervention within the first month (or year, depending on the defining organization). About 1 in 100 babies have heart defects (1%), and about 1 in 4 of those with a heart defect have a defect so severe that it needs to be corrected immediately (0.25% of all babies) Only some of these defects will be picked up by prenatal ultrasound, and they may not show up on exam before the baby goes home (or the midwife leaves in the case of a home birth). Depending on the defect, some babies may be able to compensate with structures that were in place during the fetal period but begin to go away after the baby is born.
Fetal circulation and changes after birth
By KellyPhD (Own work) [CC-BY-SA-3.0], via Wikimedia Commons
Because a fetus receives oxygen through the placenta and umbilical cord, there's no need for him to send a significant amount of blood to the lungs, so a fetus has very different heart and lung circulation than they will after making the transition to life on the outside. One of the big differences (simplified for this article) is the ductus arteriosis - this is a bypass that takes blood from the pulmonary artery and provides a shortcut to the aorta, instead of continuing on to the lungs. Another big difference is the foramen ovale - this is an oval-shaped window between the right atrium and left atrium, which allows blood to bypass being pumped out to the lungs entirely. After birth, pressure changes cause massive changes in flow. Pressure increases in the left atrium cause a flap to slam shut across the foramen ovale. Blood also finds it easier to flow to the lungs, so less blood flows through the ductus arteriosus. Over the course of days and weeks, the foramen ovale seals shut and the ductus arteriosus starts to shrivel.
Typically blood being pumped out to the body is loaded with oxygen. If there are structural problems, it's possible that this blood would be a mix of oxygenated and deoxygenated blood - there would be less oxygen available in this blood, but at least it's getting out to the body. Sometimes those fetal structures are what allows that mixed blood to circulate. So what if the baby was really depending on those shortcuts and bypasses? And then the shortcuts and bypasses go away? These babies may look well and do fine, until the fetal structures start to go away.
This March of Dimes article describes seven conditions considered to be part of CCHD:
- Hypoplastic left heart syndrome (also called HLHS)
- Pulmonary atresia (also called PA)
- Tetralogy of Fallot (also called TOF)
- Total anomalous pulmonary venous return (also called TAPV or TAPVR)
- Transposition of the great arteries (also called TGA)
- Tricuspid atresia (also called TA)
- Truncus arteriosis
Circulation after birth [GFDL http://www.gnu.org/copyleft/fdl.html
or CC-BY-SA-3.0 http://creativecommons.org/licenses/by-sa/3.0/],
via Wikimedia Commons
CCHD screening of the newborn is intended to catch babies who might need intervention, before they decompensate and their heart defects are made obvious.
The screening process
CCHD screening involves using a pulse oximeter at two locations - the right hand (or wrist), and either foot. The right arm receives its blood supply before the ductus arteriosus enters the aorta, so it's known as "pre-ductal." The left hand and the lower body receive "post-ductal" blood.
The pulse oximeter senses oxygen saturation by shining light through the skin. Red blood cells that are loaded with oxygen deflect light differently than red blood cells without oxygen. The opposite sensor collects the light and calculates how much was lost. By using multiple wavelengths of light, the unit can isolate arterial flow and disregard venous flow (veins return blood to the heart after the tissues have 'used' the oxygen the blood was carrying). For babies, an adhesive probe is typically wrapped around the hand or wrist, and then around a foot. The thin strip might be covered with a foam band to help block out the room light. Some facilities use reusable probes that are more like clips. Not all pulse oximeters are well suited for this purpose - they need to be able to sense low saturations and not be confused by an infant's constant motion.
There are three possible results from the screening - pass, fail, and an in between, or "try again."
If a baby's oxygen saturation is ≥ 95% in the right hand and foot, and there is less than a 3% difference between the two readings, then she passes the screening.
For a baby whose saturation is between 90-95%, or has a greater than 3% difference between the right hand and foot, the screening test is repeated in an hour. If she still doesn't pass or fail, she can have one more chance. If she still doesn't pass after three tries (one initial and two retries), that's considered a fail, and she should be evaluated.
If a baby's oxygen saturation is under 90% in either the right hand or foot, or she didn't pass in three tries, this is considered a fail, or a positive screening. This baby should be referred to a pediatric cardiologist who can assess her and do an echocardiogram (ultrasound of the heart), and/or other workup. Depending on her health at the time, that might mean an immediate consult, or it might mean having her scheduled for a visit soon.
In Washington state, Seattle Children's Hospital and the other regional pediatric cardiology groups are available to talk with the clinician who has a patient with a problematic screening and help figure out when and where the baby should be seen. If there is no local pediatric cardiology group, some cardiology groups can do telemetry or read studies remotely. Before implementing screening in their practice or facility, there should be a clear process for how to obtain consultation and referral (who should be called, how to contact them, how to transmit images if able, etc). Evaluation should be arranged before the baby is discharged because a baby's condition can deteriorate rapidly.
There are tools available to help with this algorithm. The Center for Disease Control and Prevention (CDC) has a flow chart to help guide the screening process, and Children's Health Care of Atlanta has a web site and Pulse Ox Tool app to help guide providers.
When should the screening be done?
The screening should be done between 24-48 hours after birth. Before 24 hours, there is an increased incidence of false positives, but a baby who passes before 24 hours is still considered to have passed (i.e., it still "counts"). If a baby is being discharged before 24 hours, the recommendation is to do it as close to discharge as possible. For babies born at home, this screening should be done at the 24-48 hour home visit, along with the metabolic screening. For the screening to be most accurate, baby should be awake and calm, but not feeding. (Feeding causes some decrease in oxygen saturation even in normal term newborns.)
What about a failed screen?
It's helpful to know that not all babies with a failed screen have a critical congenital heart defect. Like all screening tools, this screening has false positives. The false positive rate overall is about 1/200 (0.5%), but it falls to 1/2000 (.05%) when the screening is performed after 24 hours of age according to the FAQ on the Seattle Children's Hospital Pulse Oximetry Screening for Newborns resource page for providers. About a quarter of the babies who fail the screening truly have a Critical Congenital Heart Defect(true positive), while half have condition that causes low blood oxygen, like pneumonia and sepsis, and a quarter are well (false positive).
Who should be screened?
All babies should be screened, unless the baby is already known to have a critical congenital heart defect, identified during ultrasounds done during the pregnancy or immediately after birth. Most states mandate screening - 31 by legislation and one by executive order. An additional six states have regulations or guidance. In states without mandated screenings, most birth settings have adopted the screening, but not all. For some settings there are logistical challenges in terms of purchasing equipment (particularly independent midwives who might not have other use for the pulse oximeter, although since it was recommended to be used as part of neonatal resuscitation that has begun to change), arranging for consultation (particularly in rural areas or regions without adequate pediatric cardiology support), or logistical challenges in terms of who will do the screening and when. The Secretary of Health and Human Services (HHS) has recommended that CCHD screening be added to the newborn screening panel (like metabolic screening and hearing screening). The American Academy of Pediatrics also supports the universal adoption of this screening.
Cost can be a barrier in offering this screening. There is currently no procedure (CPT) code for this screening, and insurance companies are generally bundling it into the general newborn care (and not reimbursing for it as a separate service), though there are groups working to change this, since there is significant up-front investment and on-going costs in terms of probes and staff time to provide the screening. Most appropriate pulse oximeters start at $500 and the disposable probes around $3-5. Using reusable probes can decrease the cost of providing this screening.
If the hospital or midwife doesn't provide this screening, parents can ask their pediatric provider to perform the screening at the baby's first office visit. The goal is to catch these conditions as quickly as possible, ideally before the baby's condition decompensates. Getting a screening a little later is better than not getting it at all.The screening is no less accurate later on.
The childbirth educator perspective
As a childbirth educator, you can share information about this quick screening test, when you discuss other newborn care procedures. You can encourage your students to ask their midwife or doctor about the screening, or ask on the hospital tour. If the hospital or health care provider hasn't yet implemented this screening, families can ask why not, and if there's anyone they can talk to encourage implementation. Facilities and providers should hear from families that they know about this screening and expect it as part of their newborn's care. Universal screening will go a long way to identifying those children who were not previously diagnosed with a Critical Congenital Heart Defect and who can begin to receive care for the CCHD as soon as possible by pediatric cardiologists. Your childbirth class may be the only opportunity for these families to hear about and understand the importance of the CCHD screening test.
Are you already talking about this screening test for CCHD in your classes? If not, might you begin to share this information as a result of what you learned today? Are providers and facilities in your area already offering this test as part of normal newborn screening? Do you know any families who have had this screening and their baby was diagnosed with an heart defect? Share your experiences in our comments and let's discuss.- SM
References and Resources
March of Dimes, with general information about CCHD screening targeted towards families
American Academy of Pediatrics - detailed information about screening and implementation, targeted towards providers and facilities
Dr. Amy Schultz (a pediatric cardiologist at Seattle Children's) frequently presents on CCHD screening - this presentation, with detailed information about critical congenital heart defects and screening, was recorded and can be streamed online
About Dr. Elias Kass
Elias Kass, ND, LM, CPM, is a naturopathic physician and licensed midwife practicing as part of One Sky Family Medicine in Seattle, Washington. He provides integrative family primary care for children and their parents, including prenatal, birth and pediatric care. He loves working with babies! Practice information and Dr Kass's contact info is available at One Sky Family Medicine.
TagsMarch of Dimes CCHD Critical Congenital Heart Defect Newborn Screening Labor/Birth Maternal Infant Care Elias Kass