THE BEATING OF THE HEART

I

In all ages and by all peoples the heart has been looked upon as the centre of the passions, of feeling and of strength. Our word courage comes from 'coeur’—heart. Nearly two thousand years ago it was proved by physiologists that the heart was not the centre of sensibility, and yet poets and common opinion continue to say that the heart is the most sensitive part of the body.

In August 1879 Biffi showed in the Instituto Lombardo the heart of a youth, in the left wall of which, in the autopsy, he had found a needle sticking. The youth, who was of good family, was a poor unfortunate who had killed his father in a fit of insanity, had then tried repeatedly to commit suicide, and at length died mad in the hospital. While he was still living with his family, about two years before his death, he had said that he had stuck a needle into his heart, in order to put an end to his life, but no one believed him. During the whole time which he spent in the hospital the movements of the heart were regular and quiet, the pulse normal, respiration easy, sleep good; he could lie in all positions, and he never complained of any oppression in the region of the heart. When he was dead a needle with a rusted eye was found buried in the flesh and covered with a sheath which had grown around it; the sharp, polished point had penetrated into the cavity of the heart. The irritation caused by the perpetual pricking had produced fleshy excrescences at that point where the heart was continually grazed.

This instance shows how insensible the heart is, and yet, in the language of the poets and in the imagination of the people, it will always remain the centre of the passions and of feeling, because during fear, and in the decisive moments of life, we feel it hammering against the walls of the chest like a machine hidden within, the force of its contractions booming and echoing in our ears and head, exciting that strange feeling of oppression which we imagine that this rebellious organ, unchained by a storm of passion, alone produces.

The heart is nothing but a force-pump situated in the centre of the blood-vessels, which, by the play of its valves and the contractions of its muscles, keeps up the circulation in arteries and veins, driving the blood into all parts of the body, an arrangement without which life would be impossible.

II

In studying a machine one first seeks the most important part, without which it could not move nor work. In the mechanism of our body, the first part to develop and move is the heart, and it likewise is the last to stand still. The development of this organ may be better studied in the hen’s egg than in any other animal, as it can be seen on the second day of incubation. At its first appearance it is in man, as in animals, a fine, curved tube in the shape of an S. If we break an egg taken from under a brood-hen towards the end of the second or the beginning of the third day, the first rudiment of the heart may already be seen pulsating. Towards the end of the fourth week after conception, the human heart has already nearly the form which it preserves during the whole of life. It is wonderful with what resistance the heart struggles on its first appearance against every cause which threatens its life. Professor PflÜger relates that a human embryo of about three weeks’ gestation was left a whole night between two watch-glasses in a cold room. In the morning it was found that the little heart still contracted at intervals of twenty to thirty seconds, and these movements were noticeable for almost another hour, becoming gradually slower and weaker until the complete death of the embryo.

In animals incompletely developed there is no emotion capable of modifying the rhythm of the heart. In a series of experiments which I made on the heart in a hen’s egg during the first days of its development, I found that the application of the strongest inductive currents, such as were unbearable on the hands, produced not the least effect. It was a strange sight, this surprising tenacity and unexpected resistance in a little heart which was scarcely visible, and which pulsated tranquilly under electrical discharges which would have killed instantaneously the heart of a horse or an ox.

This shows us how well the organs are adapted to their functions. It is the task of the heart in the chicken to work blindly and incessantly in order to bring into circulation the little particles which gradually build up the body of the animal, using for this purpose the materials accumulated in the egg after it has received the spark of life through fecundation. In the embryo there is no need to receive the impressions of the outside world, and the organs for this purpose are still lacking, the nerves have not yet appeared, the heart is free in the midst of the chaos of matter in the course of organisation.

III

The fully-developed heart has a much more complicated innervation than the other muscles. The arm or leg cut off from the body ceases at once to move, but the heart removed from an animal continues to beat for a long time. Those who frequent the anatomical lecture-rooms notice sometimes with surprise slight movements at the base of the heart, although the rest of the corpse has been cold and motionless for a whole day. The heart owes this tenacity of life to the structure of its thin walls, to its being immersed in blood, and, more than all, to there being in its flesh little nerve-centres called ganglia. It is on this account, however, by no means independent of the brain and spinal cord, which can modify the rhythm and force of its pulsations according to the needs of the internal economy. Our organism is one of the most wonderful examples of that happy autonomy where liberty and the functions of each organ are always subordinated to the interest and advantage of all others, while the joint administration has as its object the maintenance of life and the welfare of all.

The centre of the cardiac nerves is in the medulla oblongata, in the most important part of the nervous system, near that point the wounding of which even with a pin-point causes instant death, because there all the paths of the nervous system converge.

Of the two nerves which carry commands to the heart, one serves principally to slacken the pulsations, and has, since it acts as a brake, received the name of inhibitory nerve; while the other, serving to increase the frequency of the beats, to spur them on, so to speak, is called the accelerator nerve.

The functions of the cardiac nerves, which may seem in this way to be extremely simple, are in reality very complicated. Galvani was the first who showed that an irritation of the spinal cord brought about an arrest, or, as he called it, an enchantment (incantesimo) of the heart.

IV

Boccaccio describes in a masterly manner the effects and changes which love produces on the pulse:

'Thus it happened that he sickened most seriously through excess of passion. Then were several physicians called to restore him, but, despite their careful watching, they could not guess his disease, and despaired of his recovery. And so it came to pass that one day, while a physician, still young indeed, but of profound science, sat near the patient, holding his arm there where the pulse beats, Giannetta came for some reason into the room where the youth was lying, who, when he saw the maiden, did not indeed betray his emotion either by word or gesture, but felt the ardour of passion increase in his heart, wherefore his pulse began to beat more violently than before. This the physician incontinently noticed and wondered, but remained still to see how long these pulsations would continue. When Giannetta left the room, the pulse became calmer. The physician, now deeming he had discovered the reason of the malady, caused the maiden to be called on the pretext of having a question to put to her, he still holding the patient by the wrist. Scarcely had she come into the room than the youth’s pulse beat more rapidly, slackening once more at her departure. Whereupon the physician, believing himself in possession of the truth, arose, and taking the parents of the young man aside, said to them: “The health of your son needs not the physician’s art; it lies in Giannetta’s hands.”'

So Boccaccio describes the diagnosis of the illness of the Count of Antwerp; and long before Boccaccio, Plutarch had already stated that the physician Erasistratus discovered the love of Antiochus to Stratonice from the tumultuous irregularity of his pulse.

We here touch upon one of the greatest problems which criminal science will propound in the future, when it asks the physiologist: 'Tell us of what does this man think, who remains impassive before the traces of his crime? Tell us if within him there is nothing pulsating—nothing, either human or animal?'

I have in my laboratory a dog which was of service to me in a few studies on fatigue. He is such a good animal that for two years I have kept him, together with two other dogs of which I have grown fond, and which, like old friends, shall always stay with me, unless some dog-lover comes to beg them from me, as so often happens with good, faithful dogs, that only in the physiological laboratories can escape from the certain and cruel death to which the Corporation condemns them. As he is a quiet dog, it occurred to me one day to try the effect of a violent noise upon him. I made use of a little instrument called a cardiograph, because it transmits the heart-beats to a lever which traces them on a cylinder covered with smoked paper. I applied this instrument, which is about the size of a half-crown, on the place where the heart beats between the ribs, fixing it by means of an elastic band fastened round the thorax. At first it wrote the curve of the cardiac pulsations represented in fig. 3, which is reproduced by means of photozincography. I regret having to present the reader with more curves, but when one is able to see what the heart itself writes, it would be unpardonable to try to translate its characteristic language into words. Besides, it is not difficult to understand these curves. The line T signifies the time; it is written by an electric clock which raises a pen every second and marks a tooth. It is, so to speak, a controlling line, indispensable in graphic studies by which one wishes to learn with the greatest exactness the changes which the frequency of the pulse undergoes. In the line T eighteen seconds are marked, and the heart-beats registered in the same time in line A amount to twenty-nine. If I had applied the cardiograph to the thorax of a man I should have obtained a similar curve with fewer pulsations. At each beat of the heart the pen rises and falls rapidly, and then writes below a trembling line during which the heart does not beat. As the thorax rises and expands during inspiration, the pen resting on the ribs must likewise rise, therefore the three or four pulsations taking place during the expansion of the thorax are marked successively higher, sinking again with the commencement of expiration, thus forming waves, as it were. From this curve, traced while the animal was tranquil, we see that its heart, as indeed is also the case in man, beats more frequently during inspiration than during expiration, the heart-beats being nearer to each other in the ascending portion of the curve, and further apart in the lower portion which corresponds to the end of each expiration.

While the animal was perfectly quiet I motioned to my servant to fire a gun, but he failed. It was an old hunting-gun, badly loaded perhaps, and only the cartridge had caught fire. The dog, however, at once tried to rise, and became strangely excited, much to our surprise. I had my hands on the instrument which lay on the ribs where the heart beats, and felt that its palpitations had become stronger and more rapid. About a minute later we succeeded in taking the curve B in fig. 4, from which may be seen how much more frequent the pulsations were. The animal had become so restless that we had to give up the experiment and set him at liberty. When he was on the ground he went round the laboratory sniffing everywhere. Presently we took the curve C, fig. 4, from which we can see that the emotion was not yet over, since the beating of the heart is still quicker than in the normal curve marked in fig. 3.

There were several of us together when this experiment was made—the students of the laboratory, my assistants, and Professor Corona, and we were all astonished at what took place. Some of the bystanders said at once that it must be a hound. We had always taken him for a watch-dog, as he was very big, and did not look in the least like a hound. We determined to try a decisive experiment the next day.

We waited till the animal was perfectly quiet, and then held a gun so that he could see it at a distance of a few steps from him, without threatening him in any way. The dog at once recognised the weapon, and again grew excited, showing a considerable change in the cardiac curve.

But the most evident proof that it was a hound was given by the very violent emotion and the unexpected excitement which took possession of him as soon as he heard the noise caused by the loading of the gun and the click of the trigger. Even when he saw nothing, and this noise was made at some distance from him, the beating of the heart changed instantly (as may be seen in the following curve), and the animal tried to rise and sniffed the air.

The curve D, fig. 5, shows the pulsations written with the cardiograph applied to the thorax of the animal when quiet.

At a given time I signed to a person, whom the dog could not see, to load the gun. Scarcely had the animal heard the clicking than he moved; a few seconds passed, during which it was impossible to take the curve, the dog being so restless. About a minute later I succeeded in obtaining the curve E, fig. 6, in which one can see that the form of respiration, as well as the frequency and force of the cardiac pulsations, is altered.

After we had assured ourselves that these alterations of the pulse were much less marked after other noises which did not resemble the loading of a gun, we wished to convince ourselves whether the agitation was caused by a fear of weapons. The next day the dog was again brought into the laboratory, and while he lay on the table, and the action of the heart was being marked, someone walked past him with a gun on his shoulder. The dog recognised it again, became restless, tried to rise, his heart beat violently, he began to wag his tail, and followed the hunter with satisfied glances.

V

When strong emotions such as fear are concerned, one must have recourse to other methods of writing the pulse, as the animal is very uneasy and tries to escape. As this is a question as yet little considered in physiology, I shall communicate a few experiments which I made bearing upon it. Fig. 7 represents the pulse of the carotid artery of a dog. During line F the animal was quiet; the pulse is somewhat irregular, which, in the dog, is a physiological fact. In line G five normal pulsations may be seen, while at A a shot was fired two steps from the dog. The report caused such a vibration of the air that the pen trembled, as may be seen from the irregular outline of the first two pulsations. The effect of fear on the heart is immediate. The frequency of the beats becomes at once three times greater than before.

We waited till the dog was quiet again. Fifteen minutes afterwards the curve H, which represents the normal pulse-line, was written, then came six pulsations of the line I, while at B a second shot was fired, and immediately the pulse was accelerated.

But why does the heart beat more rapidly and frequently in fear? In order to explain the cause of this phenomenon I must remind the reader of the observations which I made during my studies of the pulse, and of the circulation of the blood in the human brain during sleep. In a sleeping person, at the slightest noise or touch, the pulse becomes more frequent without the sleep being interrupted. This change is indispensable in order to accelerate the circulation and to utilise to the utmost the strength of the organism in preparing it for defence. Our machine is so made that it changes automatically as required, without the interference of the will being necessary. The palpitation of the heart from fear is the exaggeration of a fact which we always notice, whenever the organism must develop its maximum of energy and increase the circulation in the nerve-centres; the heart does not work for itself, but for the brain and muscles, which are the instruments of combat, attack, defence, and flight.

The greater or lesser frequency and force of the pulse in emotion depends upon the greater or lesser excitability of the nerve-centres. Women and children, who are more sensitive, experience this palpitation in greater intensity. When we say that women have more tender hearts, we refer to the fact that their hearts respond to stimuli to which the hearts of men remain impassive. We say of anyone who blushes and grows pale easily, and is soon moved to tears or laughter, that he has a good heart and a sincere character. But even cold, sceptical, egotistic, impassive men, when they are suffering from some illness, or when the excitability of their nervous system is intensified by some cause or other, may be deeply moved, and betray their feelings like children.

One must be a physician in order to see how the most courageous men become faint-hearted at a trifling loss of blood, and timid people, in consequence of a more abundant flow of blood to the brain, perform miracles of bravery. Weakness quickens the heart-beat even when we are not moved by anything. We all know that we avoid giving certain news to the convalescent which at other times would have produced little effect upon them.

One of my colleagues had been ill eight days from a quinsy. When he recovered and came to the laboratory, I hastened to visit him, and found him sitting in an arm-chair, pale and exhausted. I asked him how he was, to which he answered 'Very well,’ but that while scolding his servant on account of some trifling matter, such a feeling of oppression had seized him that he had to desist, as he was scarcely able to draw breath. I felt his pulse, and found that it was above a hundred. He laughed, and said, 'I never dreamt that my strong body was such a paltry piece of machinery as to run down during the few days I have not eaten as usual.’

VI

It is necessary for the heart, as for all muscles, to be fed. For it, indeed, this need is more imperative, as it may not stand still in order to rest when it is tired. The continuous work to which it is condemned explains to us how every alteration in the composition and amount of blood is immediately manifested by changing its nutrition and consequently its strength. Knowing that the heart is in constant contact with the blood, that is, with the nutriment distributed by it to all parts of the body, one might think that it could in this way take the best part for itself, as it helps itself at first hand; at the least, that it would take a more abundant portion than the other organs, or that nature allowed it to satisfy its appetite unreservedly. But this is not the case. In our body the rations of all organs are calculated and distributed according to the need of each. There is also a very strict economy of nutrition observed, because when any part of the body works more than usual, its increased needs are supplied by diminishing the rations of the other organs. The vaso-motor nerves are charged with this distribution of victuals, if I may so express myself. The heart, like all other muscles, takes as much blood as it needs for its maintenance out of its cavity by means of the coronary arteries branching off from the aorta. There is a control exercised over the heart also, and the vaso-motor nerves could, if it were absolutely necessary, diminish its rations and leave it barely sufficient strength to distribute the food to all the other parts of the body.

Physiologists have endeavoured in vain during the last centuries to find in the greater or lesser nutrition of the cardiac muscle the cause of its more or less accelerated movements. One of the most daring theories was propounded by Giovanni Lancisi, the celebrated Roman court-physician, one of the most illustrious physiologists Italy has ever possessed.

In his book 'De motu cordis,’ printed in the year 1728 by the Roman University Press, he develops a theory so manifestly materialistic of the origin of the pulsation of the heart during emotion and mental suffering, that it seems almost impossible the book should have been dedicated to the memory of Clement XI. and printed with the pontifical types, by permission of the Sacred College. The Roman curia did not foresee that those first steps would lead physiology so far away from their dogmas, and did not suspect that such simple notions about the functions of the human machine were pregnant with the innovative germs of modern philosophy, since it allowed its great physician to speak freely, and since it furnished him with the means for his physiological investigations, heaped honours upon him, and handed down splendid editions of his immortal books to posterity.

Mental functions are placed by Lancisi in close dependence on the nerves, the ganglia, and the coronary vessels of the heart. The material organs it is which influence mental movements. The heat of passion, the storm of emotions, have in the heart mechanisms by which they may be moderated and regulated. It is as though the nerves and ganglia of the heart, by driving the blood with more or less violence into the brain, could excite the instincts; as though the character and disposition of the mind depended on the material structure and the physical modifications of the body.