Hearts Made for More

Even now, in the short, dark days of this pandemic extending past the solstice and the turn of the calendar, our viral nemesis is not the greatest threat to years in life and life in years. Even now, with more than 350,000 deaths in the United States attributed to SARS-CoV-2 since this time last year, another assailant steals more of our loved ones from us, this year and every year.

That assailant, and there are several others nearly as bad, is cardiovascular disease. Every year in the U.S., well over 650,000 succumb to heart disease, and many if not most of those deaths are premature, if anything more so than for COVID. And, like COVID, heart disease produces “long haulers” as or more often than it kills. Congestive heart failure, cardiomyopathy, and diastolic dysfunction are illustrative labels for hearts permanently damaged by our cultural contagion of lifestyle-induced chronic diseases.

The matter of lifestyle demands three particular reflections. 

First, the flagrant fact of outsized influence on heart disease by lifestyle - diet, physical activity, stress, toxic exposures, etc.- is incontrovertibly established. Where lifestyle prevails as medicine, generally mediated more by cultural norms than extremes of personally responsible effort, heart disease is reduced to a rounding error of its mainstream prevalence. There is no rebuttal to the contention that at least 80% of all coronary disease could be eliminated with a simple suite of salutary lifestyle practices, and a general consensus the figure is much closer to 100%. Like smallpox and polio, coronary artery disease is potentially eradicable; lifestyle constitutes the requisite vaccine.

Second, even causes have causes. One cannot speak equitably of lifestyle practices without conceding that the playing field of opportunity is precipitously inclined. For some, environments all but preclude healthful food selection, safe outdoor recreation, or the avoidance of toxins including frequent duress. There are genetic undercurrents, too, but far more important to outcomes than one’s genetic code is one’s zip code. The choices we make are subordinate to the choices we have, and those in turn are bounded by social and spatial and built environments. Like COVID, the toll of heart disease is mediated by these.

And then third, a crucial consideration along a departing tangent. For the ghastly, perennial toll of eminently preventable heart disease derives not only from lifestyle practices gone awry on a bedrock of social, ecological, and economic disparities. It derives as well from the confluence of physiology with a parade of poets through the ages, and their propounded passions. All that poets have had to say about the heart- is true.

Consider that the heart is arguably the hardest working construct in the body. If we adopt the lower end of a normal heart rate, namely 60 beats per minute, and apply that across a lifespan of 80 years, that heart will beat 2,522,880,000 times. It will never rest, for it never can. It can be called upon for greater effort, but never lesser.

There is so much more. Feel your own pulse- you can find it most readily in the radial artery, just at the base of your thumb where it meets your palm. You will note that the pulse is short relative to the pause between pulses. Each pulse represents systole, the contraction of the cardiac ventricles that drive blood throughout the body (and lungs). The space between pulses corresponds with diastole, the inter-beat period of ventricular recovery and respite.

Now, if inclined to play along to a full, empirical appreciation of the point in development- please jump up and down (if you can do so safely), or do jumping jacks, or pushups, or lunges- for 30 seconds. Now, check your pulse again.

You will note that your heart rate has shot up. While the pulses themselves may have shortened slightly, mostly the reactive tachycardia (i.e., fast heart) you are discerning is drawn from diastole. That’s where most of the time to pack in more heart beats per minute resided; from there, that time was drained. Stated bluntly, with increased demands on the heart, diastole- the heart’s recovery time- is by requirement diminished.

There’s more. Like all working muscle- or any living tissue for that matter- the heart requires constant oxygen and nourishment across the thick expanse of its myocardium (i.e., cardiac muscle). How are these provided?

The heart is “fed” via coronary arteries. There is a left, and a right, and branches of each we needn’t explore in detail here. The coronary arteries open directly from the aorta, the body’s great artery, just beyond the leaflets of the aortic valve. The cardiac choreography of life, every minute of it, is as follows: the right and left ventricles fill to capacity while relaxed, and that filling upon completion slams shut the “doors” leading into these chambers, the tricuspid and mitral valves, respectively. That is the famous “lub.” Then, the ventricles contract to express the blood that fills them, and once they empty to the requisite degree, the “doors” leading out slam shut in turn- the pulmonic and aortic valves, respectively- and that, of course, gives us “dub.”

The span from “lub” to “dub” is systole. Diastole populates the expanse from each lub/dub cycle to the next. 

That expanse shortens- potentially by quite a lot- when the body has cause to ask more of the heart. It has such cause every time we climb a flight of stairs; carry groceries; become alarmed. From the trivial activities of homely routines to the supreme feats of great athleticism, the body calls, and the heart answers.

The heart answers ever, and always, at its own expense. For when the body has greater need of oxygen, fuel, and the flow of blood that delivers these- so, too, does the heart. To increase its delivery and fulfill the demand, the heart beats both faster and stronger. These amplify the energy expended by every myocardial cell, and in tandem- their need for oxygen and fuel. Therein lies the great cardiac conundrum that explains why heart attacks are so much part of our cultural zeitgeist, but spleen attacks are not; thyroid attacks are not; tibial and femoral and humeral attacks are not. The heart, and only the heart, attenuates its own access to breath for the sake of all other organs. 

When heart rate goes up, diastole shortens. Diastole is when the heart breathes. Diastole is when the blood pouring into the coronary ostia from the base of the aorta must race through the full thickness of myocardium before that muscle contracts yet again. A tight run race it is, under the best of circumstances. Slow the flow through the coronary arteries with some atherosclerotic plaque, and then compound that liability with an elevated heart rate that truncates diastole- and all too often it is a race to the death. Think of it in this graphically simplistic way: the heart must breathe between its own beats that give away breath to the rest of the body.

The heart is all that the poets have ever said: generous, selfless, steadfast to the fullest measure of devotion. How well that perpetual pulsing represents the poetic impulse to find in its cadence redoubtable courage, relentless fortitude, and something very near the romance of heroism.

That tale, in its every incarnation, is written in the rhythms coursing through our many inner miles. That will do- you may take your fingers off your radial pulse now.

The year has turned, and we take the pulse of a year that has exacted a great toll. In part, because of what fell upon us all. In part because of our cultural neglect of the native health that was the best bulwark against this new assault. But largely, too, because of all the ways we fell apart, and turned on one another.

As we take the pulse of a passing year, I am inclined to find more meaning in our own. In our every pulse there is a fervor of expression to rival Shakespeare; passion to put Byron and Beaudelaire to shame; a selfless devotion to something other than self that could goad even saints to greater charity.

If our hearts within us are made for so much more than themselves; if selflessness pulses in our chests- we need never send to know for whom that cadence tolls. It tolls for thee. And me. 

Our hearts within us were made for better than discord and division, and arguably then, so were we. With our every exertion, hearts bequeath their very breath to service the greater body’s common cause.

Well we may lament the cost of this where preventable coronary atherosclerosis compounds the toll. We might simply marvel at it. 

Better, though, that we strive in some small measure to emulate it, and march to the primal beat of the drummer within.

-fin

Dr. David L. Katz     is a board-certified specialist in Preventive Medicine/Public Health.

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