“Amazing. You can see straight through to the left ventricle,” Josh said. “Look at that. Will you sew it closed or patch it, Alec?”

The defect Alec and Pete tackle in The Stars That Govern Us is the ventricular septal defect or VSD. This page supplements the novel and discusses the condition in a little more detail.

Public Domain – Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities.

A ventricular septal defect (VSD) is a congenital heart defect involving a hole in the wall between the ventricles, or pumping chambers, of the heart. About 42 in every 10,000 babies are born with a ventricular septal defect, and prior to the invention of the heart-lung machine, children with significant defects would be expected to die in childhood or as young adults.

The ventricular septum is the wall of fibrous tissue and muscle that separates the right and left sides of the heart’s pumping chambers. The heart is a double-sided pump, and keeping the two sides separate is critical; pressure on the right side of the heart (responsible for sending blood to the lungs) is very low, while pressure on the left side of the heart (responsible for pumping blood out to the body) is very high.

A VSD, is, essentially a shunt. In children with a VSD, blood from the left ventricle flows through the hole and into the right ventricle and lungs. This extra blood and the higher pressures force the lungs and the heart to work harder than usual. This leads, over time, to complications including heart failure, pulmonary hypertension, arrhythmias, and strokes.

Prior to the invention of the heart-lung machine, a child’s prognosis and life expectancy were mostly dependent on the size and location of their defect and the presence of other problems; symptoms could begin at birth (or shortly thereafter) or many years in the future.

VSDs are sometimes associated with other inheritable congenital conditions, particularly Down Syndrome, but in most cases, there is no known cause. VSDs can also exist alongside other congenital heart problems. For example, the Tetralogy of Fallot is four separate congenital heart defects, one of which is a VSD.

Treatment for a VSD in 1956 would have been through open-heart surgery as depicted in the novel and would have been considered very high-risk, with mortality rates approaching up to fifty percent in the early days. Today, smaller VSDs may be observed to see if they close on their own or are treated with medication while larger VSDs may be repaired through cardiac catheterization or through open-heart surgery.