WILTYIMS #223: Defects

We had a lecture today yesterday was on congenital heart defects. Here are some of the facts I found particularly interesting:

TIL: A person can be born with a double aortic arch. You might rightly think this shouldn't be a major problem because it's simply a redundant (if super large) blood vessel. Problems arise not because of blood flow, but because the second arch completes a circle around the the esophagus and trachea/bronchi. This leads to problems swallowing and breathing.

Coarctation of the aorta is a narrowing of the superior descending aorta and is one of the only things that will make you listen for the heart sounds through the patient's back. The aorta naturally arcs backwards and the stenosis occurs just on the downturn so that the noise of the blood whooshing through is best heard on the back, between the scapulas.

Ventricular septal defect (VSD) causes left sided volume loading because the volume ejected during systole never returns to the RV. Blood squeezed through the defect from left to right will go straight into the pulmonic valve and back to the left side.

A "tet spell" is a temporary event that occurs in children with the condition called tetralogy of Fallot, a fairly common constellation of heart malformations. Tet spells are caused by increased resistance through the pulmonary artery (it's not known why this happens) which causes all the deoxygenated blood longing for the lungs to go through a hole in the septum. The deoxygenated blood just cycles back to the body, causing the child to turn blue and faint.

And finally, when is the one time you want a septal defect? If you are born with a transposition of the great arteries (the aorta and pulmonary artery) you need a septal defect to survive long enough for surgery.Transposition of great arteries sucks. In effect, the two paths of blood from the heart are switched creating two parallel and thus useless circuits. Oxygenated blood from the lungs goes right back to the lungs and deoxygenated blood from the body returns to the body. The only way to survive is if you have another birth defect: a hole between the two sides of the heart.