Last week during morning rounds, I was in the newborn nursery auscultating heart and breath sounds of each brand new infant. As I came across this one beautiful baby, I noticed that its heartbeat sounded completely different. Normally, you can clearly distinguish between the first heart sound (S1) and the second heart sound (S2); however, this baby’s S1 continued straight into the S2 sound in a harsh high pitched-blowing manner. This was my first time auscultating a ‘holosystolic murmur’ in real life. Bare in mind I had heard dozens of simulations, done dozens of questions and read about this type of murmur for many years before I actually got to hear it with my own ears. This type of murmur in infants typically raises suspicions of a hole in the heart or abnormal blood flow such as regurgitation, and also demands screening for the critical congenital heart defects (CCHDs) which include: Hypoplastic left heart syndrome, Pulmonary atresia (with intact septum), Tetrology of Fallot, Total anomalous pulmonary venous return, Transposition of the great arteries, Tricuspid atresia and Truncus arteriosus. Babies with CCHDs usually require surgery or catheter intervention in the first year of life and the majority of them will go on to live healthy lives post-operation. In the United States, about 7,200 (or 18 per 10,000) babies suffer from one of these conditions each year.
The human fetal heartbeat can be detected as early as four weeks into pregnancy. By week six, fetal cardiac activity is visible via transvaginal ultrasound. At twenty weeks gestation, the fetal heart looks like the one here. During our development within the mother’s womb, each one of us had a hole in our heart known as the “foramen ovale.” While in the womb, a baby does not breathe in oxygen, but instead receives oxygen from the mother’s blood supply. Blood flow from the mother actually bypasses the baby’s lungs and is directed through the foramen ovale and pumped into the aorta to supply the fetal head and body. At birth, once the baby’s lungs become functional and the baby takes its first breath, this blood is then shunted towards the baby’s pulmonary circulation. This precise moment is when the baby oxygenates its own blood cells for the first time! The pressure changes in the heart due to the inhalation of oxygen, force the foramen ovale to then close. If this hole fails to close however, it can result in a condition called patent foramen ovale (PFO). Other conditions in which a hole in the heart persists include atrial septal defects (ASD), ventricular septal defects (VSD) & Tetralogy of Fallot (TOF). These defects can range from being benign / asymptomatic in presentation to life-threatening where they are classified under the category of “critical congenital heart diseases.”
As a medical student, there is something about experiencing real-life situations that we have been training for which makes me more eager to learn each day! That way, I too can learn to save lives on the daily.
Next week, we will be continuing our hole in the heart series and elaborating more on the holosystolic murmur that was originally discussed.
Written by Student Doctor: Navpreet Singh Badesha ©07/21/2017 All Rights Reserved.
For more statistics on PFOs, check out this study from the National Library of Medicine.
