Heart and thoracic aorta

The thoracic aorta, deep in your chest, is not something most of us contemplate very often. Yet it can play a crucial role in your long-term health. It can determine, for instance, whether you have a stroke at age 65, develop aortic valve disease that needs to be remedied by surgical replacement of the valve to keep you alive, or have numerous other health conditions, all centering around this several inch-long artery (shown in the diagram as the purple tubular structure).

A quick anatomy lesson: the thoracic aorta is the biggest artery in the body, the first artery that receives high-volume, high-velocity, high-shear blood flow that is ejected with each heartbeat from the main pumping chamber of the heart, the left ventricle. Each time your heart beats (contracts), around 80 milliliters (just under 1/2-cup) of blood is ejected past the aortic valve and into the thoracic aorta, around 5 liters (roughly 5 quarts) of blood every minute. The thoracic aorta, normally about 3 centimeters (1.2 inches) in diameter, arises from the heart, ascends in the chest cavity, turns left (your left), then descends into the lower chest and abdomen, giving rise to the arteries of the neck/brain, arms, abdomen, pelvis, and legs along the way. But it is the initial several centimeters of thoracic aorta that is the recipient of this high-pressure, turbulent flow and the source of most health problems arising from this blood vessel.

I learned to respect the thoracic aorta by reviewing tens of thousands of CT heart scans and echocardiograms over many years of clinical practice in cardiology in which we readily see this piece of human anatomy with such imaging tests. The health of the thoracic aorta is not something you can gauge with crude measures like cholesterol, not something you can feel or detect on your own, but is readily measured by these simple tests (although it is typically not mentioned in narrative reports until it reaches near-aneurysmal diameters; see below).

By far the most common abnormality of the thoracic aorta is enlargement. A normal unstressed ascending thoracic aorta measures 3.0 cm (a little smaller in shorter females, a little larger in tall males). If it reaches 5.5 centimeters, it is then labeled a “thoracic aortic aneurysm” and becomes life-threatening because it can rupture, causing hemorrhage into the chest cavity that kills you within a few minutes. Or the internal paper-thin lining of the aorta can tear, causing what is called a “dissection” associated with excruciating pain with consequences determined by whether the torn lining blocks bloodflow into the carotid arteries to the brain or other large vessels. Both are painful and catastrophic, both of which you want nothing to do with.

One of the common consequences of a diseased thoracic aorta before it reaches aneurysm stage are so-called “mini-strokes,” typically experienced as loss of the capacity for speech, use of an arm or leg, or other neurological disabilities that last only a day or two, but leave your brain with some measure of permanent impairment. Doctors assess the carotid arteries in the neck for bulky atherosclerotic plaque that may have fragmented, showering fragments into the brain, or they look at the heart for clots, but usually find nothing and declare that the mini-stroke has no identifiable source. But the source is frequently fragmentation of atherosclerotic plaque in an enlarged thoracic aorta. In other words, an enlarged aorta is a diseased aorta, even if it has not yet reached the definition of an aneurysm because it commonly becomes lined with atherosclerotic plaque. As the recipient of the high-volume, high-pressure blood flow from the heart, you can imagine that atherosclerotic plaque can tear or fragment, sending debris to your brain (and sometimes other organs such as the kidney).

Having an enlarged aorta, even if only 3.4 or 3.7 cm, tells you that there is something wrong with your health that is causing the aorta to enlarge. Blood pressure is a big player here, as the thoracic aorta essentially acts like a balloon, responding to the pressure within. Having an ideal blood pressure is therefore important in not allowing your aorta to enlarge.

Good news: If you are already on the Wheat Belly or Undoctored lifestyles, you are already on a program for thoracic aortic health. The lack of wheat and grains (eliminating provocation of small LDL and VLDL particles), the collection of nutrients that address nutrient deficiencies common in modern life (vitamin D, omega-3 fatty acids, magnesium, iodine), and basic efforts to cultivate a healthy microbiome (thereby reducing endotoxemia) all contribute to generating an ideal blood pressure, reducing or eliminating insulin resistance and inflammation, and reduce arterial wall injury. And, of course, if you have begun to engage in strategies I outline in my Super Gut book, you have taken on dysbiosis, SIBO, and endotoxemia.

But there is another neglected factor here that I have been discussing lately: the modern collagen-depleted lifestyle. In other words, unless you make a habit of eating the skin and organs of animals, boiling the carcass for soups, stews, and broths, and slow-cook tough cuts of meat, all to mobilize collagen, you are not obtaining the collagen required to strengthen the thoracic aorta. Because many people do not want to engage in consuming organs or these other efforts, resorting to the convenience of collagen hydrolysates or peptides is a really good idea. More good news: getting sufficient collagen in your diet also smooths skin wrinkles, rebuilds joint cartilage and increases joint lubricant (glycosaminoglycan), reduces blood pressure, and may even contribute to preservation of cognitive health.

If you have had a CT heart scan or echocardiogram (heart ultrasound), you want to look at the narrative report to see whether the diameter of the thoracic aorta was reported. If not, you should call the center that performed the study and insist that they measure it. You would be shocked at the number of times a diseased and enlarged aorta of, say, 3.9 or 4.2 centimeters, a degree that predicts an aneurysm, dissection, or risk for phenomena like mini-strokes, but is reported as “normal.” This is the infuriating bias of modern healthcare: If a condition does not lead to near-term need for a drug or major procedure (e.g., replacement of the thoracic aorta, a major undertaking with high mortality), it’s not a problem, even if the condition could lead to catastrophe within a few years.



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