Not The Most Diligent

Okay, I may or may not have been a wildly ineffectively blogger for the past few weeks.

I understand this. Let's all just move past it.

We left off at the beginning of the Cardiopulmonary module. The first half the module, Cardio, is now over and I'm pleased to report it was a rousing success. While I now know more than I ever wanted to about the electrophysiology of the heart, it has been interesting and a good module. We've learned much more doctor-ly things such as how to read ECGs (there actually is information in those squiggly lines) and listen to the various heart sounds (<--INTERACTIVE!). To me, learning about heart defects has been one of the more interesting subjects. While I won't go into big hairy details, one aspect is too cool not to share. In general, I think we can all agree that having a heart defect would be an unfortunate thing. That is, unless you've got more than one defect. Sometimes, having a heart defect can actually save your life. More on that later, but first, a bit of background to fully appreciate what's going on here.

Your heart is made up of four chambers (atria and ventricles), separated by four valves, and can be divided into left and right halves. The ventricles are the lower chambers of the heart and are the real workhorses. The atria (plural for atrium) function to kind of "prime" the ventricles and keep the blood flowing.

Blood that has been in your body (deoxygenated) flows into the right atrium. From here it passes through the tricuspid valve and into the right ventricle. The right ventricle pumps blood through the pulmonic valve and into the pulmonary artery where it goes to the lungs to gain oxygen. Once the blood has oxygen, it flows from the lungs and into the left atrium. From here, the blood passes through the mitral valve (named for a bishop's mitre) and into the left ventricle. The left ventricle pumps blood through the aortic valve and into your aorta where it goes to your entire body and provides that much needed oxygen.

Having a hole in your heart that changes this flow of oxygenated/deoxygenated blood constitutes a fairly large number of heart defects and many of them either close on their own or can be fixed. (In fact, when you're growing in the womb, it's normal and necessary to have one so your blood bypasses the lungs.) But I digress.

One major heart problem is called Transposition of the Great Vessels (technically dextro-TotGV, but we're simplifying here). Because of a problem during development, a person's pulmonary artery and aorta are switched. Aside from this sounding scary (which it is), it prevents blood from undergoing its normal exchange of oxygen. Oxygen-rich blood simply cycles from the lungs, through the left side of the heart, and back into the lungs. Oxygen-depleted blood from the body enters the right side of the heart and is pumped into the aorta and back in to the body. Having this defect on its own is, as they say in school, "incompatible with life." (How's that for cold medical talk, eh?)

"Bad News"---^

Now you may be asking yourself (if you're still reading), Okay, Matthew, where does the coolness of this all come in? Cause right now, you're just talking about fatal heart defects.

I understand, dear reader(s). The cool part about this is that if a person has transposition of the great vessels AND another hole-in-the-heart defect (such as Patent Ductus Arteriosus or Atrial Septal Defect), the second defect allows just enough oxygen to intermingle and flow what is normally the wrong way that the person stays alive. When this dual defect is coupled with the (hopefully) astute actions of the medical team delivering the baby, the doctors are able to recognize what's going on, rush the baby into surgery and swap the vessels around to where they are supposed to be.

That's right, crazy-emergency-heart-surgery-on-a-baby-that-has-a-success-rate-of-OVER 90%. Medicine FTW! (FTW= For the Win)

Until next time. (Which will be much sooner- I know, I know.)