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— Niall O'Higgins
— Kevin Barraclough
— Joseph Perloff
— Dorian Deshauer
The world around us is overflowing with rhythms. We are always coming into contact with them, from the moment we are born. The rocking of the cradle and the singing that goes with it are both rhythms; so are the flash of a lighthouse beam and the roar of waves crashing against the shore, the rattle of a train and the croaking of frogs by the tracks. The world's rhythms pervade us, bringing in their own meter and stirring a response. Among primitive peoples rhythm is associated with the beginning of life. On the Polynesian islands a god molded a figurine of woman-as-the-mother out of clay and then danced before her for three days and three nights. Drums accelerated the rhythm, while with every movement of his dancing body he implored and incited her. Until finally-as Czeslaw Milosz writes-matter could no longer maintain its own inertia. The first shudder of rhythm ran through the figurine, waking her from an ageless sleep. Her first response was shy: she stuck out one knee, testing to see if she were really made of something other than earth.
Or maybe the rhythm beaten out on the drums came from deep inside the universe? Was it perhaps aroused by signals flowing frominterstellar space, steady and regular, emerging from inside rapidly rotating colossi that make our sun look like a speck of dust? Known as neutron stars, these gigantic concentrations of matter, the sources of powerful magnetic and gravitational fields, send radio waves of great intensity into the universe-and to us as well. They are typically so perfectly regular that the centers where they arise are called pulsars. So is it impossible to imagine that the pulsars imposed their rhythm on the beating drums, and that the first pulse of blood that ran through man, stirring him into life, was a response to their rhythm? Was the human pulse set off by the pulsars of the universe?
It is not just the world that sends its rhythms coursing through us. There are also rhythms inside us. There are so many rhythmic processes happening in our bodies, from the obvious ones, like sleeping and waking, to the most well hidden, like the secretion of hormones into the blood, that to explain their uncanny regularity and synchronicity we have adopted the figurative idea of the biological clock. Long before it was discovered, everyone agreed that if this extraordinary chronometer really did exist, then every last cell of our bodies would be able to tell the time from it.
Nowadays we locate it in the brain, in the part called the hypothalamus. The biological clock runs in two concentrations of gray matter, known as the hypothalamic nuclei, and so does its most essential part-the circadian oscillator. The clock's mechanism appears to be determined by a cycle of recurring reactions: the transcription of genes and the synthesis of proteins. These reactions form a feedback loop: so-called clock genes code proteins, which accumulate and retroactively obstruct the transcription of genes. As protein disintegrates, transcription gets going again, and the protein production cycle is resumed. This "clockwork" system, characterized by rhythmicality, is common to all species, from the fruit fly to man. It is teamed with the emission of circadian signals, which depend on changes in the cell's membrane potential. Once in existence, they spread into the nearest vicinity and to other areas of the brain as well.
But what use would a watch be if you couldn't set it to local time? The biological clock is buried in the brain just above the intersection of the optic nerves. Converted light signals take a short cut to bring it a constant supply of information about the world, just as the neurons that make up its structure provide it with information from inside the body. Within the "clock-gene" mechanism the rhythms of the internal and external worlds converge and harmonize.
Some people's biological clock runs fast. At the dawn of the third millennium several families were identified in the state of Utah, all of whose members-from grandparents to grandchildren-wake up four hours earlier than everyone else. They leap out of bed feeling full of energy, while their neighbors remain fast asleep for some time to come. Their clock seems to be set four hours ahead. In these early birds there has been a change in a single little letter, a nucleotide in one of their clock genes. Or perhaps the "night owls" carry a different, subtle genetic mutation within their clock? Medicine is now starting to look for drugs that can interfere in the working of the biological clock, to correct the disagreeable jet lag that we experience after transatlantic flights, for example. Will a new kind of doctor emerge in the future ... known as a "clockmaker"? Will the Polish minister of health have to add a new medical specialty to the current list of seventy-two? And to avoid confusion with clockmakers, will he give these specialists a scholarly name, "chronologists," for instance?
Of the many rhythms beating away inside our bodies the heartbeat is the one we care about most, perhaps because it has always been the hallmark of life-both biological and emotional. Doesn't the doctor listen to his patient's heartbeat just as attentively as the novelist listens to his hero's? Don't both of them borrow each other's words to describe the heart's condition, saying that it is throbbing, fluttering, or fading?
As far back as the longest-lasting consistent civilization ever to have existed, the world of ancient Egypt, the heart played an enormous role, as the center of psychological strength too. It comes into poetry, religion, and hieratic texts, and rises to the rank of not only the central organ in the body, but also the main seat of the emotions-virtually becoming "the essence of the essence" of man. In the era of the Old Kingdom, five thousand years ago, nothing but a man's heart would be tossed onto the scales at the posthumous judgment of Osiris. To be pure, a heart set on the scales before the god had to weigh less than the lightest feather. Otherwise, it was immediately gobbled up by a monster waiting by, and the Egyptian's life beyond the grave ended in eternal ignominy.
As for the heart, it's not so much its harmony with the rhythms of the surrounding world as its rhythm's independence that is its most amazing feature. Think back to our school biology lessons-if you remove a frog's heart and put it on the table top, it goes on beating for several long minutes. Every day in hundreds of operating theaters all over Europe surgeons stop a sick heart and cool down the body to perform complex operations, and once they've finished, they set the heart going again with an electric shock. During transplantation the heart taken from the donor's body is left on its own for several hours in a nourishing liquid that is simple to make; later on it ends up inside an organism that is alien to it, but once aroused by a current applied to its walls for a split second, it starts up a steady beat. These examples show that within the heart itself there must be a mechanism capable of setting it going rhythmically.
This mechanism is made up of specialized cells that generate and distribute impulses. They are not scattered at random, but are linked to form a compound structure. We call it the automatic system of the heart or, more often, the conductive system. The first name stresses the independence and above all the infallible, mechanical regularity with which the system works, and the second emphasizes the role it plays in dispersing the impulses. Large clusters of cells within the system form nodes, or stations, between which the impulses run along the tracks of fibers. Just like an army at the front, the conductive system has its own hierarchy, assuring that leadership is continually handed on in the event of the leader's death. At the top of the hierarchical ladder stands the sinoatrial, or sinus, node, which sets the pace, or takes the first step. It produces the highest-frequency impulses and thus stifles all the other potential pacemakers, dictating the rhythm of the entire heart. If it should become impaired, the role of leader is assumed by the next nodes down the hierarchy, successively setting rhythms of lower and lower frequency. When they too fall silent, the heart activates its emergency rescue mechanism, concealed in the muscle, and starts beating at the slowest rhythm that will guarantee a supply of blood to the organs at rest but will not allow for any effort at all. In such cases we speak of total heart block, as the intermediate stations and previously passable routes to them have been destroyed or obstructed.
What are the signals we have followed to make the journey from the first station right through to the last? We describe them as being electrical in nature, and we say that they come into being when fissures appear in the cell walls, tiny channels along which some charged atoms drop inside and others drop out. This event recurs rhythmically, causing potential differences. The electrical discharges travel along the routes familiar to us all the way to the muscle fibers, where they set off a contraction. But inside the cell walls, who opens the gate to such a precise rhythm, allowing the charged atoms to leap through in opposite directions? What sort of metronome beats out this primary rhythm, which sets the rhythm of the heart? We don't know the answer, and even with the idea of an electrical current we are skating over the surface of what actually occurs.
Do our hearts beat with the mechanical perfection of a metronome? Not everyone's does, as the following explanation shows. Impulses repeatedly continue to arise in the cells of the sinoatrial node to a perfect rhythm, like the beat of the most sensitive of metronomes. But before an impulse leaves the node, in order to disperse along the trails created for it and prompt the heart to contract, it experiences the extremely subtle influence of the sympathetic nervous system. This is a very delicate effect, which as a rule we are unable to detect with a stethoscope. However, we can perceive it by analyzing a long electrocardiogram recording. When we measure the gaps between consecutive heartbeats over a period of several minutes, we notice that in many of us there are tiny differences between them, and that they deviate from the average by hundredths of a second.
This reminds us of the musical tempo rubato, which is a typical feature of Chopin's work. There are lots of familiar definitions of Chopin's rubato. Some say it describes performing a composition "with a subtle rhythmic anxiety." Other say that rubato relies on "tiny shifts between the notes of the melody within the range of its own beat, against a steadily paced bass." Franz Liszt characterized Chopin's rubato by comparing it to a tree, "when its crown bends in all directions in the wind, but its roots are stuck firmly in the ground."
Chopin used the term rubato to denote playing senzo rigore in his mazurkas and nocturnes written in the years 1824-1835, but from 1836 he stopped using it. According to Gastone Belotti the reasons for this are obvious: as soon as he reached maturity all his compositions were to be played rubato.
There are some hearts in which the rubato, that "subtle rhythmic anxiety," clearly registers, as in Chopin's mature work, and there are others in which-as in his earlier, youthful work-it is not perceptible. When struck by a dangerous illness, the former are less likely to stop suddenly, as if a lack of stiffness, a sort of flexibility, or a tendency toward a free and easy beat had prepared them better for the onset of malevolent, morbid rhythms. Analysis of these discreet deviations from the perfect rhythm under the influence of the nervous system (known as "heart rate variability") is finding ever wider application in assessing the risk of sudden cardiac arrest in patients who have already suffered a heart attack.
Doctors have always set great store by examining the pulse and have become highly proficient at it. In the third century BC Herophilus of Alexandria assessed separate phases of the pulse by using a clock of his own construction, which he took with him on visits to his patients. For centuries the pulse rate has been tested by all possible means, in the not unreasonable belief that it will provide a way to discover the secrets of how the heart and the entire body function. Only a few years ago medical students had to stand at the patient's bedside and define in a single breath such basic features of the pulse as its regularity, frequency, intensity, fullness, and tension. The terms used to encapsulate the main quality of a pulse must have seemed countless, as they spoke of a bigeminal pulse, a thready, or filiform, pulse, or when they ran out of adjectives, a paradoxical pulse. Surely in the present era of omnipotent technology all this knowledge has fallen by the wayside? Not at all-the 2000 edition of the renowned Dorland's Medical Dictionary, advertised as a compendium of the most essential information for medical practice in the third millennium, describes eighty-two different types of pulse!
Naturally, examining the pulse has had its stiffest competition from listening to the heart. The French doctor René Laënnec was the founder of auscultation; one day, to avoid placing his ear inappropriately close to the chest of a young female patient, he rolled a piece of paper into a tube, tied it with string and set it to her heart, never for a moment imagining that his invention would open up a whole new world of sounds-the ones that are literally closest to us, but that had been closed to our hearing until then. Arrhythmia provides the perfect example. A single extrasystole is like a slight stumble in a dance-one little sway that we don't even notice before we pick up the rhythm in the next step and it sweeps us onward. A heartbeat that is punctuated by recurring premature contractions makes us think that syncopation was not the original discovery of jazz musicians. In atrial fibrillation the pause between contractions changes, while the rhythmic accent shifts. The pace of a galloping horse can be heard in left heart failure (the "gallop rhythm"). The beating of a heart affected by a total block is interrupted at lengthy intervals by noisy "cannon fire" (when the atria and ventricles contract simultaneously), which is repeated by a faint echo of the atria contracting.
Echo was the name of a mountain nymph. The Greek myths give various explanations for how she came to personify a disembodied, recurring voice. After falling in unrequited love with Narcissus she sank into such despair that she began to disappear, until nothing was left of her but her voice. In another version, for keeping Zeus's love affairs secret Hera condemned Echo to repeat the last word of anyone who spoke to her. Not surprisingly, as new languages arose, they began to repeat her name. She found herself a home in them for ever, ultimately becoming one of the most frequently used words in modern medicine. Echo, echosonography, echocardiograph.... We penetrate the heart with sound waves, and they bounce back, returning to us as an echo, from which we can construct an image of the heart itself, one that is astoundingly precise in its details. The diagnostic equipment is developing so fast you might think it was trying to catch up with the perfect echolocation techniques of ... bats.
By revealing the details of the anatomy of the heart or the power of its muscles to contract, the echocardiogram enables us to understand the causes of heartbeat disturbances. An electrocardiogram then enables us to diagnose them. An especially valuable tool is the around-the-clock ECG recorder, popularly named the Holter after an American doctor. It produces a diary, written by the heart, recording every single one of its contractions, and of course every, even the briefest, arrhythmia or ischemia. This record is an invaluable aid in everyday medical diagnostics. More refined analyses are also being developed to detect subtle asynchronicities in the action of the heart. Mathematicians and physicists are helping medical researchers with these extremely complex phenomena by applying the dynamics of nonlinear systems and chaos theory.
What a range of facilities there is nowadays for medical students trying to fathom the music of the heart! We lay a diaphragm fitted with an electronic amplifier over the sternum, at the point where the ribs join. It has six pairs of acoustic ducts coming out of it, just like the tube of an ordinary stethoscope. This allows six people to listen to the sounds issuing from the same point above the heart simultaneously. Meanwhile, the screen of a portable computer displays an electrocardiographic curve, and beneath it a phonocardiogram-a nonstop recording of all the tones, murmurs, and other acoustic features produced by the heart. You can stop it, "freeze" it, and analyze it.
Excerpted from Catharsis by Andrzej Szczeklik Copyright © 2005 by University of Chicago. Excerpted by permission.
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|3||The elixir of life||21|
|4||A tangle of serpents||33|
|5||In between art and science||42|
|6||The rhythm of the heart||55|
|7||A purifying power||68|
|11||After the genome||114|
|12||Alterations and returns||131|
Posted November 8, 2009
No text was provided for this review.