Pulmonary Hypertension

I think the hardest of all of Nathan's conditions for us to try and explain and for other people to understand was pulmonary hypertension.  But in order to understand a number of things going forward, it becomes really important to understand it.  So here goes...

Pulmonary Hypertension is a persistent, abnormally high elevation of the pressure in the blood vessels of the lungs.  Essentially it is "high blood pressure in the lungs."  For convenience sake, that's how we generally referred to it when talking to others.

In order to better understand Pulmonary Hypertension and its effects and dangers, it's important to understand the normal workings of the circulatory system.

Blood that has been circulated through your body is brought back to your heart into the right atrium, where it is then moved to the right ventricle.  From there it is transported through the pulmonary artery to the lungs, where it is oxygenated from the air that you've breathed in.

The blood is then taken back to the heart into the left atrium, where it is then moved to the left ventricle, and then out to the body through the aorta to repeat the process all over again.

As the blood is circulated through the body, it exerts pressure on the walls of the blood vessels.  This force is known as blood pressure.  Normally, the left side of the heart produces a high blood pressure in order to pump the blood to the body.  The right side of the heart pumps blood to the lungs under a much lower pressure.

In pulmonary hypertension, the small arteries in the lungs are too narrow, thus restricting the normal flow of blood through them, which then causes the pressure in the vessels to rise above normal levels, resulting in an increased resistance to blood flowing through them, as can be seen in the diagram below.

In addition, the blood pressure in the pulmonary artery also rises above normal levels.  Sometimes far above normal levels. As a result, the right side of the heart, the side that pumps blood to the lungs, has to pump against a higher resistance to blood flow.  This makes it more difficult to pump the blood through the lungs.

The increased resistance places a strain on the right ventricle, which has to work harder than usual to move adequate amounts of blood through the lungs.  Over time, the right side of the heart may become enlarged, as can be seen in the diagram below.

If the right ventricle enlarges too much, it may struggle to function properly.  In many such cases, blood is often forced backwards through the tricuspid valve, as shown below.

If left untreated, eventually, the heart will fail.