Critical Congenital Heart Disease (CCHD)

What is CCHD? 

Critical Congenital Heart Disease (CCHD) refers to conditions where structural complications exist in the heart and great vessels around the heart. These conditions are called critical because affected newborns require surgery or catheter intervention in the first year of life to ensure their survival.

CCHDs that can be screened for with pulse oximetry include: hypoplastic left heart syndrome, pulmonary atresia (with intact septum), tetralogy of Fallot, total anomalous pulmonary venous return, transposition of the great arteries, tricuspid atresia and truncus arteriosis.

What is the incidence of CCHD?

Approximately 3 per 1000 babies will have CCHD.

Why should we offer clients pulse oximetry screening for CCHD?

Pulse oximetry is a simple, non-invasive screening test that measures the level of oxygenation in the arterial blood of newborns and is a recommended standard of care. Pulse oximetry screening is the best approach to identify asymptomatic newborns with invisible hypoxia. 

Approximately 50% of newborns with CCHD will be diagnosed by ultrasound in pregnancy, and another 20-30% will be identified during physical examination of the newborn by the following signs and symptoms: heart murmur, central cyanosis, tachycardia, tachypnea, feeding difficulties, low birth weight or delayed weight gain, excessive sweating, pale cool or clammy skin and lethargy. However, many infants with CCHD have no clinical signs before decompensation.

It is important to note that compensatory cardiac measures can allow a newborn with CCHD to appear well, and the condition may be missed in the first few days of life. Newborns primarily have fetal hemoglobin at birth, which has higher oxygen affinity, and their oxygen saturation (SpO2) levels can decrease to 75-80% before cyanosis becomes visible.

Pulse oximetry testing can detect low oxygen saturation before physical assessment findings are apparent. With the addition of pulse oximetry screening for CCHD, earlier detection and improved outcomes can be expected for about 50-100 babies each year in Ontario. 

How accurate is pulse oximetry screening for CCHD?

The sensitivity of pulse oximetry screening (proportion of people with the disease who have a positive result) is moderate at 76.5%.

The specificity of pulse oximetry screening (proportion of people without the disease who have a negative result) is very high at 99.9% for detection of CCHD. 

The false positive rate for detection of CCHD is significantly lower when screening occurs at or after 24 hours, with no difference in sensitivity.

1. Pulse oximetry CCHD screening false positive rate < 24 hours of age:  0.5%

2. Pulse oximetry CCHD screening false positive rate ≥ 24 hours of age:  0.05%

When is the best time to perform pulse oximetry screening for CCHD, and why?

Evidence supports pulse oximetry screening of newborns between 24 and 48 hours of age, with an optimal window of 24-36 hours of age.

In the first 24 hours of life, as newborns transition from fetal to newborn circulation, the ductus arteriosis may remain patent causing transiently low SpO2 and higher false positive results of 0.5%.

Screening after 24 hours allows sufficient time for the ductus arteriosis to close, significantly lowering false-positive results to 0.05%.

Delaying screening beyond 48 hours increases the risk of a rare undiagnosed newborn with CCHD to rapidly deteriorate, increasing the risk of organ damage and life-threatening complications.

If a screen is done in the first 24 hours of life and results in a screen positive/REFER, can I wait and retest in the recommended window (24–48 hours)?

No. Health care providers must respond to screening results as they arise whenever the screen is done. A positive screen in the first 24 hours is a positive screen and the newborn requires immediate consultation with a physician. To reduce the likelihood of false positive results, it is recommended to screen between 24 and 48 hours of age.

Who performs pulse oximetry screening for CCHD? Where is it done?

It is likely that CCHD screening for most midwifery clients will occur in the community setting and screening will be done by the midwife or midwifery student; however, if the client is in the hospital at 24-36 hours, CCHD screening may be conducted by a nurse.

How do I perform pulse oximetry screening?

Screening is best done when the infant is awake, in a quiet, non-fussing state prior to any disruptive care activities (e.g. bloodwork) and can be conducted while breastfeeding. 

CCHD screening should be offered as part of an informed choice discussion. It is not a mandatory screening; all parents have the right to decline. Document declined CCHD screening on the newborn postpartum record, as well as the reverse side of the screening sheet and return it to NSO.

The following newborns do not require CCHD screening: those already diagnosed by prenatal ultrasound or by physical assessment within the first 24 hours of life, or any newborn in the NICU/SCN/PICU with cardio-respiratory instability and an expected length of hospital stay longer than 7 days - all who are receiving appropriate monitoring and treatment.

The following NSO educational resources are comprehensive and informative:

• NSO video (demonstrates CCHD pulse oximetry screening in the community)
• NSO CCHD screening algorithm (outlines how to interpret screening results)
• NSO screening evaluation chart (provides a tool for evaluating pulse oximetry results)
• NSO CCHD decision pathway (assists with decision making for CCHD screening evaluation)

Where do I document CCHD pulse oximetry screening results?

The NSO blood spot form has been modified to include a detachable CCHD page within the form, with matching bar codes. This CCHD sheet can be removed and conducted at a different time from the dried blood spot screening if necessary. Document the date and time of screen, pre- and post-ductal result, as well as the interpretation of the result (PASS/REPEAT/REFER) and forward as usual to NSO.

If the parents decline pulse oximetry screening, document relevant information on both sides of the NSO CCHD screening results sheet and forward to NSO.

What is a screen negative or "PASS"?

Any screen with SpO2 ≥ 95% in the right hand or either foot with a ≤ 3% absolute difference is considered a negative screen “PASS”. 

Receiving a negative screen or “PASS” for CCHD is reassuring, however, the newborn’s caregivers should be aware that the screen does not detect all CCHDs. Optimal management includes routine physical examination of the infant and teaching about signs and symptoms of the unwell baby, and when to page the midwife if they develop, in addition to pulse oximetry screening to detect potential concerns.

What is a screen positive or "REFER"?

1. Any SpO2 (oxygen saturation) measure < 90% (in the initial screen or in repeat screens)
2. SpO2 <95% in the right hand and either foot on two (community setting) or three (hospital setting) measures¹, each separated by one hour, or
3. A > 3% absolute difference in SpO2 between the right hand and either foot on two (community) or three (hospital) measures¹, each separated by an hour

Receiving a positive CCHD screen or “REFER” does not necessarily mean that the newborn has a CCHD. The false positive rate for “REFER” results is 0.05% when performed ≥ 24 hours.

¹ A midwife may choose to arrange for a third screen and physician assessment in hospital, and not perform the third screen in the community setting. The rationale for this is twofold. First, it is highly unlikely a third screen will result in a “PASS” after two “REPEAT” screens, and second, time required to arrange for a consultation and to move into hospital for a physician assessment delays potential treatment for the newborn. Arrangements for a referral with a physician will vary depending on access to referral services (e.g. distance to hospital, time of day and availability of physician).

Why wait an hour between screens in the event of a "REPEAT" result?

The optimal timing between screening and frequency of rescreening has not been studied; however, studies with rescreening have most commonly used a one-hour interval to provide more time for the transitional circulation to adapt and decrease false positive results.

Why monitor SpO2 for 30 seconds during screening?

NSO has adopted this standardization of screening times, including 30 seconds of monitoring per screen to allow for a comprehensive look at the newborns’ saturation values over time.

How likely is it that the newborn will need a second (or third) screen?

It appears the need for repeat CCHD screening is infrequent from the limited research found on this topic (rates varied from 0.9-1.8% repeat tests performed).  In one U.S. quality evaluation (3) of 7828 CCHD screens performed in hospital using the same hospital screening algorithm recommended by NSO:

• 99.1% of newborns received a negative screen or “PASS”
• 0.9% of newborns required a second screen or “REPEAT” result, of these:
  • 79% received a negative 2nd screen or “PASS”
  • 21% received a 2nd “REPEAT” result
• 0.2% of newborns required a 3rd screen, of these:
  • 100% received a “REFER” result or a screen positive
• 1 newborn of 7828 newborns screened was diagnosed with a CCHD (less than the typical incidence of approximately 3 per 1000 babies who will have a CCHD)

How do I arrange an immediate consultation with a physician for assessment?

Consultation processes differ by community.  Some midwifery practices may page pediatrics on call or the emergency room physician for a telephone consultation and send the newborn (with NSO CCHD results sheet and consult note) to the hospital for immediate assessment. 

Immediate assessment is understood to be within 2 hours of screening (although this may not be possible in rural or remote communities).

Depending on the larger clinical picture with a screen positive (more than one “REPEAT” result or a “REFER” result), midwives may call ahead and send the baby in with parents by car (if close to hospital, and baby appears well); or call EMS for urgent transport if baby appears unwell (cyanosis, tachycardia, tachypnea, feeding difficulties, delayed weight gain, excessive sweating, lethargy, pale cool or clammy skin).

How can I prepare my client for next steps in the event of a positive screen?

An immediate consultation with a physician should occur to evaluate for causes of hypoxemia.  This evaluation will include a comprehensive assessment involving the following:  four limb BP; femoral pulses, full vital signs and pre- and post-ductal saturations. 

Additional diagnostic tests such as electrocardiogram, chest X-Ray and/or other tests to rule out other non-cardiac causes of cyanosis may be ordered.  If the most likely cause remains cardiac or is unclear, consultation with paediatric cardiology and an echocardiogram is warranted to rule out CCHD.

What are the implications of false positive and false negative results?

A false positive screening result occurs when a healthy individual is incorrectly given a positive screening result.

False positive screens will result in the newborn and parent(s) going to the hospital and having an assessment by a physician, which may also include a fetal echocardiogram or possibly in other interventions.  There may, however, be value in false positives:  false positive screening may detect other conditions such as infections or pulmonary/respiratory disorders such as pulmonary hypertension.

A false negative screening result occurs when an individual with a CCHD incorrectly receives a negative “PASS” screening result.

The moderate sensitivity rate of pulse oximetry screening for CCHD means that approximately 23% of newborns with a CCHD or other congenital heart defect will not be detected with pulse oximetry screening alone.  Missed CCHD screens are associated with multiple congenital malformations, low birth weight, prematurity, intrauterine growth restriction and critical congenital heart defects associated with obstruction of the aorta (coarctation) and interruption of the aortic arch.

Why did NSO change the recommended timing of the newborn screen (dried blood spot screening), to 24-48 hours after birth?

The recommended timing changed based on a literature review conducted by NSO suggesting that earlier screening will be lifesaving for 5-10% of infants diagnosed using the dried blood spot screen.

Are there any additional resources?

• NSO CCHD educational resources, screening tools and e-Learning modules:
  • CCHD e-Learning Module (for first time learners)
    • Interactive learning module about CCHD, screening practices and evaluation of results for first time learners.
  • CCHD Recertification e-Learning Module (recertification)
    • Interactive learning module about CCHD pulse oximetry screening, for recertification purposes.
• PulseOxTool app aids clinicians in screening for CCHD; contains an algorithm that allows clinicians to calculate whether the result is negative or positive.
  • Download via App Store or Google Play.
• Wisconsin Shine Heart Atlas provides anatomical information on the heart and CCHD with diagrams and brief descriptions of the 12 target diagnoses of the disease.
• Refer to the AOM’s Normal Newborn Behaviour document for clients (for signs of an unwell baby).
• Visit the AOM’s Pulse Oximeter Maintenance and Cleaning Instructions webpage.

References

1. Andrea J. Implications of Using Pulse Oximetry to Screen for Critical Congenital Heart Disease in Newborns. Nurs Womens Health. 2015;19(4):314–23.
2. Thangaratinam S, Brown K, Zamora J, Khan KS, Ewer AK. Pulse oximetry screening for critical congenital heart defects in asymptomatic newborn babies: a systematic review and meta-analysis. Lancet (London, England). Elsevier Ltd; 2012 Jun 30;379(9835):2459–64.
3. Pflugeisen BM, Amoroso PJ, Zook D, Welke KF, Reedy A, Park M V. Quality improvement measures in pulse-oximetry newborn heart screening: a time series analysis. Pediatrics. 2015 Feb;135(2):e531–9.
4. Lhost JJ, Goetz EM, Belling JD, van Roojen WM, Spicer G, Hokanson JS. Pulse oximetry screening for critical congenital heart disease in planned out-of-hospital births. J Pediatr. 2014 Sep;165(3):485–9.