VSD: Assessment & Diagnosis

"Prenatal screening programmes typically recommend detailed assessment of fetuses judged to be at high risk of congenital heart disease. However, most cases of congenital heart disease arise in the low-risk population, and detection of affected fetuses in this setting depends on recognizing abnormalities of the heart during the midtrimester scan (Hunter, 2014)".

Current recommendations focus on screening newborns for CHD in the well-baby nursery and in intermediate care nurseries or other units in which discharge from the hospital is common during a newborn’s first week of life. Timing the screening around the time of the newborn hearing screening can help improve efficiency. A pulse oximeter is used to measure the percentage of hemoglobin in the blood that is saturated with oxygen (CDC, 2022).

Ventricular septal defect is often not diagnosed before 4 to 8 weeks of age. Prior to this age the lung's alveoli are not completely opened. As a result, there is high pulmonary artery resistance. This resistance limits the amount blood shunted through the defect.

As lungs develop, pulmonary circulation expands and pulmonary resistance decreases. When pulmonary resistance falls below the pressure generated by the left ventricle, blood will flow across the vsd toward the area of lower pressure.

If a child shows signs of congestive heart failure, further assessments are made. Findings that suggest VSD include:

• At about 4 to 8 weeks of age, a loud, harsh, systolic murmur may be heard along the left sternal border at the 3rd or 4th interspace. The murmur is widely transmitted and a thrill may be palpated.

• The additional shunted blood to the right side, and extra work the right side has to perform to pump this blood, leads to right-sided cardiac enlargement. Xrays and ECGs will indicate right ventricular hypertrophy.

• Echocardiograms/ultrasound and magnetic resonance imaging (MRI) will also show right ventricular hypertrophy. They will also show pulmonary artery dilatation from the increased blood flow.

• Cardiac catheterization procedures measure oxygen saturation levels and pressures in the vessels and ventricles. With VSD, the oxygen saturation level of the right ventricle is higher than normal, because oxygenated blood is entering this ventricle through the defect. If pressure in the pulmonary artery is measured with the catheter, it will generally be above normal because of the increased flow in the vessel.

Instant Feedback:
Ventricular septal defects are commonly diagnosed in the first few days of the neonate's life.

With VSD, the oxygen saturation level may be higher than normal in the right ventricle.

References

CDC, (2022). Congenital Heart Defects Information for Healthcare Providers. Accessed April 25, 2022 from: https://www.cdc.gov/ncbddd/heartdefects/hcp.html

Hunter, L. E., & Simpson, J. M. (2014). Prenatal screening for structural congenital heart disease. Nature reviews. Cardiology, 11(6), 323–334. https://doi.org/10.1038/nrcardio.2014.34

Kemper AR, Mahle WT, Martin GR, Cooley WC, Kumar P, Morrow WR, Kelm K, Pearson GD, Glidewell J, Grosse SD, Lloyd-Puryear M, Howell RR. Strategies for implementing screening for critical congenital heart disease. Pediatrics. 2011; 128:e1-8 (Graphic from https://www.cdc.gov/ncbddd/heartdefects/hcp.html)