Why screen for heart defects?
Congenital heart defects affect approximately 8 out of every 1,000 babies born. More than 35,000 babies are born each year with heart problems, and the most serious — known as complex heart defects — sometimes require surgery in the first weeks of life. Because the circulation of the fetus changes immediately after the first breath, complex defects must be identified and treated quickly to give the child the best possible outcome.
With innovations in surgical technique, babies born twenty years ago who did not survive now have a chance at productive lives. More than one million adults in the United States are living with congenital heart defects today. Earlier detection means better newborn care and improved long-term outcomes — which is why we provide a screening examination of the heart during each trimester of pregnancy, and maintain one of the highest fetal heart problem detection rates in Southern California.
Causes of heart defects
Over 90% of heart malformations have no known cause. For this reason, most physicians classify heart defects as multifactorial — the result of complex interaction between hereditary and environmental factors. Since most defects arise from pregnancies with no risk factors at all, many physicians now recommend examining the heart in every fetus.
Known risk factors include
1st trimester screening
12 to 15 weeks · complimentary
In 2002, Dr. DeVore wrote an editorial titled "First-trimester Fetal Echocardiography is the Future Now", in which he reviewed the medical literature and proposed that heart defects could be detected as early as 12 weeks of pregnancy. With the introduction of universal first-trimester nuchal translucency screening for Down syndrome, the Fetal Diagnostic Centers have had the opportunity to scan thousands of fetuses in the first trimester and apply the principles of fetal echocardiography during the NT examination.
In a study performed at the Fetal Diagnostic Center we reported detecting complex heart defects at a rate of 4 per 1,000 — equal to what is expected in the general population at birth. Almost all of these defects would not have been detected without examining the heart in great detail using sophisticated ultrasound equipment.
Performed at no cost. At present we are not reimbursed by insurance companies for this study, so we offer it free of charge as part of our commitment to quality care during a "routine" 1st trimester examination — which would otherwise only require us to measure fetal size and the nuchal translucency behind the fetal neck.
Our ultrasound approach uses high-resolution transducers with color Doppler of blood entering and leaving the heart. The exam includes a transabdominal study and in many cases an endovaginal examination, which often provides more detailed images of the fetal heart.
Normal anatomy
A comparison of heart images obtained using an abdominal probe versus an endovaginal probe — the endovaginal approach provides more detail of cardiac anatomy.
4D power Doppler rendering of the cardiovascular system at 12 weeks of pregnancy — used when there is concern for an identified malformation.
Abnormal findings
13 weeks — coarctation of the aorta
Sweep demonstrating findings consistent with coarctation of the aorta: a larger right ventricle than left ventricle, a ventricular septal defect, and tricuspid regurgitation.
Normal at 13 weeks, abnormal at 17 weeks
At 13 weeks the left (LV) and right (RV) ventricles measured the same size with normal contractility. By 17 weeks the left ventricle was dilated and poorly contracting. This fetus had severe aortic stenosis which developed into a serious malformation requiring surgery following birth — a powerful illustration of why serial examinations matter.