Tag Archives: Blood

BLOOD VESSELS: HUMAN “PULMONARY CIRCULATION”

Humans have a high energy requirement. Like a sports car we need to be turbosupercharged. We need an entirely separate Pulmonary circulation to handle our great oxygen demand.

Fish can get by on a single heart and circulation. They are “cold-blooded” and have no elevation of temperature above that in the environment. The water buoys them up, and they don’t need to constantly fight gravity.

Birds, and by extension, therapod dinosaurs, need more efficiency, and have a separate pulmonary circulation, just like we do. They share with us a DOUBLE CIRCULATION, a 4-chambered heart, with 2 entirely separate circuits.

In my residency, I saw a lot of congenital heart disease. In the process of development, the very early human embryo has a single circulation, just like “early” vertebrates, like fish.

In the process of development, the Systemic and Pulmonary circulations divide the previously unitary system into 2 separate systems, by a continuous spiral of partitions, or “septae”.

Ontogeny recapitulates Phylogeny: Development recaps Evolution. If this process of separation fails to happen in a given child, Congenital Heart Disease is the result:

  • IASD. Interatrial Septal Defect is failure to separate the Atria, the upper chambers of the heart;
  • IVSD, Interventricular Septal Defect, is failure to separate the Ventricles, the lower chambers of the heart;
  • AV Communis is both of the above, plus failure of Atria and Ventricles, the upper and lower chambers, to separate, giving one big inefficient chamber.

When you listen to the hearts of these children, there are prominent murmurs, or noises, which betray the presence of turbulence and inefficiency, the very thing that evolution “tried” to prevent.

In the normal Human Heart, the blood returns from it’s systemic circuit through the capillaries, depleted of oxygen, into the vena cava. It passes to the Right Atrium, through the tricuspid valves, to the right ventricle.

With the contraction of the heart, the blood goes through the pulmonary artery, into the pulmonary capillaries, into close contact with air-containing alveoli. The oxygen passes through the alveolar membrane into the capillary blood, which becomes red. The oxygenated blood then passes into the pulmonary veins and on into the left atrium, and the systemic circulation.

It is interesting, and essential that the systemic arteries contain red, oxygenated blood, and the Pulmonary artery contains blue, oxygen-depleted blood. The “tired” blood, returning from the body must be “pepped up” by passing through the pulmonary circuit, picking up oxygen in the process.

Similarly a clot, originating in a quiet vein, perhaps a dilated, or varicose vein, is pumped into the Pulmonary circuit, where it lodges in the tiny capillaries and produces a PULMONARY EMBOLISM.

The embolus clogs the pulmonary circuit, increasing resistance, raises the normally-low pulmonary artery pressure and produces PULMONARY HYPERTENSION, placing more load and strain on the Right Ventricle.

Pulmonary Hypertension is also caused by a variety of Lung, heart, inherited and kidney diseases, as well as by certain drugs, high altitude, and Obstructive Sleep Apnea.

Please check the Mayo Clinic discussion that follows.

–Dr. C

Pulmonary Hypertension Article

IN THE LAB: TESTS FOR AND DIAGNOSING “aNEMIA”

I should have known something was wrong.

I was getting short of breath with a third of a 45-minute exercise I had done for years, but I rationalized it away. I reasoned that I hadn’t been sleeping well, I am getting old. And my heart isn’t working as well because of the Atrial Fibrillation.

Physicians have a big armamentarium of excuses they can generate, and besides it is their Karma to GIVE Medical care rather than to RECEIVE it.

The AHA moment came when I bumped my leg, and peeled back some skin. My skin is old and fragile, and I’m always tearing it in small areas.

This time, I got to see the blood run all the way down my leg like a drop of grape juice, not the thick blood I’m used to. If anything, my blood should be thicker, more viscous, since my average Hemoglobin is 16 gm., on the high side of normal.

I got my blood drawn, and ordered a CBC and a ferritin. The CBC shows the Hemoglobin level, and a number of other measurements bearing on anemia, and the ferritin gives a measure of IRON STORES.

I can’t remember the first time my ferritin was ordered, or why, but it has for years been borderline, just barely in the normal range, dipping down as low as 18, and rising as high as 35.

Since a common cause of low iron stores with a good diet is colon cancer, I had about 3 colonoscopies to rule out cancer over a period of 6 years; lucky me.

At least they were all negative, and without polyps.

This time the ferritin was 12, well into the abnormal range, and the Hemoglobin was 8.6 gm. little more than half my usual.

I had been fibrillating for 5 months, and been on 5 mg. Eliquis ( an anticoagulant/blood thinner) for the same period. Having a recent normal colonoscopy, the most likely diagnosis was AVMs (arteriovenous malformations) of the small bowel, with bleeding accelerated by the Eliquis,

Since small bowel surgery contraindicated a diagnostic videocapsule, this diagnosis would have to remain an assumption.

I reduced the Eliquis by 25%, calculated my blood loss rate and started 2 capsules of feosol alternating with 3 capsules daily. Over a period of 4 months, my Hemoglobin came back up to 15 gm., and my ferritin came up to 50. I am due another test as soon as I get enough nerve to brave the Covid and go to the lab.

This story is a good illustration of treating one illness, and thereby creating another in this world awash with medication. How much better it is to stay as healthy as possible.

However, I am becoming increasingly aware of the fact that Health is not often the top priority in most peoples lives.

As an illustration, I refer to todays’ Sunday New York Times, which reviewed 2 books on walking, one written to praise its’ health benefits. To quote the reviewer, “

The issue with ‘ in praise of walking’ is Mr. O’Mara’s assumption that how good an activity may be for us is the most essential measure of its worth”. Praising health raises an issue?

Personally, my main exercise is walking, and I do it expressly for health. That doesn’t mean that I don”t enjoy walking and have other motivations. I would not be walking as FAST, however, it it were not so healthy.

–Dr.C.