OUTLIERS MEDICAL-FORENSIC FILES: Congenital Heart Disease by DP Lyle, MD

OUTLIERS MEDICAL-FORENSIC FILES: Congenital Heart Disease by DP Lyle, MD

What Congenital Heart Defect Might My Female Family Members Suffer From?

Q: I'm trying to construct a family of women who have a congenital heart defect. The mother has died from it. The older sister dies as the book begins. The middle sister is suffering, and her imminent death is part of the plot. (She's 18). What I'd like is for her to be treated by surgery, but a surgery the poor girl can't afford. The youngest (12) may or may not have the problem. (I can live with either.) So far, I've found coarctation of the aorta, but I have no clue what it means. Could the older sister simply have a worse and inoperable version?

A: Coarctation would work as would an Atrial Septal Defect (ASD) or Ventricular Septal Defect (VSD). Each, if untreated, can lead to death over time and each can be surgically repaired.

For the circumstance you described, I would go with an ASD. This is not a rare congenital heart problem, and it can be inherited. So, your two sisters could have inherited the defect. The severity and the rate of progression and the time required to become inoperable are extremely variable and depend on two things–the size of the defect and time.

Let me explain the physiology, which is very complex, but hopefully I can make it understandable. Our circulatory system is divided into two separate parts—left and right. The systemic, or arterial, circulation is the left side of the heart (left atrium and left ventricle) along with the arteries and veins of the body. This feeds the entire body with oxygen and nutrients. The right side of the circulation is called the pulmonary (lung) circulation and consists of the right atrium, right ventricle, and the pulmonary arteries and veins.

The entire circuit is a large figure of eight. Blood pumped from left ventricle goes out to the body through arteries and returns to the right atrium through the veins. Then, the right ventricle pumps the blood in the lungs, where it collects oxygen and dumps carbon dioxide, before returning to the left atrium through the pulmonary veins. The process continues in this fashion with every heartbeat.

The two sides of the circulation are separate and have no communications. But, in an ASD, or a VSD, the two sides connect to each other through the defect. In a VSD, the defect is in the ventricular septum, which separates the left and right ventricles. In an ASD, the defect is in the atrial septum, which separates the left and right atria.

The pressures throughout the left side (systemic) are much higher than are those on the right (pulmonary). For example, the systemic systolic pressure–the one obtained when someone measures your blood pressure–is typically around 120, while the pulmonary systolic pressure is typically around 30. As long as the two sides are separated, there’s no problem, but when a defect is present (ASD or VSD), the blood preferentially flows through the defect from the higher-pressure left side to the lower-pressure right side. In an ASD this happens between the two atria. This means that part of the blood coming in from the lungs that normally would be pumped out to the body, is diverted (we call this shunting) to the right side. Thus, the pulmonary blood flow is increased relative to normal. As the years go by, this increased flow causes the pulmonary arteries to become thicker, which in turn, increases the pulmonary pressure.

As long as this pressure is below 40 or 50, the person does fine. From 50 to 70 or so they develop fatigue and shortness of breath, particularly with any activity. Once the pressures reach 80 or 90, the pulmonary arteries are severely damaged. These individuals are typically inoperable. With pulmonary artery pressures that are normal or only slightly elevated, the risk of the surgery is extremely low. When the pressures reach the 50 to 70 range, the surgery is a riskier but still doable, and most of these people do well. Once the pressure reaches the 80 to 90 range operations no longer work because closing the defect can lead to fatal heart failure. The physiology here is too complex to explain and you don’t really need to struggle with that to write your story.

In your story, the mother and older sister could have had ASDs that weren’t diagnosed early enough to repair and thus they did not survive. The middle sister could have a significant issue but be operable. The younger sister could have a milder issue, or none at all.

For decades, the standard treatment for an ASD or VSD was open-heart surgery where a patch is sutured over the defect. This is still done for larger defects. But newer techniques allow the patch to be placed through a catheter. This does not require opening the chest or the use of the heart-lung bypass machine, and is performed in a Cardiac Cath Lab. In the former, the person is in the hospital for 5 to 7 days after surgery, while in the latter they often go home the next day. Each can be an expensive procedure, so either could fit your requirements.

DP Lyle MD

https://www.dplylemd.com/