19. Tricuspid insufficiency wwwwww 10. I come case as fig. 9. Left radial. 20. Complicated heart disease." Original Communications. motion of the end of the lever is accurately and permanently recorded. The two portions are immovably attached to a metallic frame, by which the whole is firmTHE SPHYGMOGRAPH, AND SOME OF ITS ly bound over the artery, the pulsations of which it is USES: desired to investigate. BEING THE SUBSTANCE OF A PAPER READ BEFORE THE NEW understood by an examination of the woodcut, fig. 1. The construction of the first portion will be readily YORK MEDICAL JOURNAL ASSOCIATION, BY SAMUEL B. WARD, M.D., NEW YORK. DESCRIPTION OF THE INSTRUMENT. QR is a brass rod, immovably fastened to the frame. K is a flat piece of ivory, intended to lie over the artery, and attached to the rod QR by the spring I, which keeps it firmly pressed against the artery, and yet allows THE best instrument which we have at present for the it to move up and down with each pulsation. By means study of the pulse is Marey's Improved Sphygmograph. of the screw P the amount of this pressure can be As the name is formed from the two Greek words ouy-increased or diminished. DBE is a comparatively light uós, the pulse, and ypápew, to write-so the instru- brass rod which rotates freely around a pivot at E, and ment itself may be considered as composed essentially which is terminated at D in a knife-blade. CA is a long, light lever, which rotates around the point C, the only resistance being the light, curved spring Y, which presses it downward. The end of the lever A is armed with a pen. The instrument needs to be applied quite firmly; and the pressure made by the artery against the piece of ivory K carries it, with the spring to which it is attached, upward, until the upper surface of the spring touches the rod BE. It then carries this rod, which rotates around the fixed point E, still further upward, until the knife-blade D touches the under surface of the lever CA at a point very near the centre of motion, C. The bar DBE is in a different plane from the bar QR, and moves freely past it without touching. Now it is necessary that the end of the lever A should vibrate opposite the centre of the paper on which the trace is to be received; otherwise the pen would be raised too high with each pulsation, or drop too low after the wave had passed. This object is accomplished by means of the screw TN, which is a long screw with a milled head, working entirely free both of the lever CA and the bar QR, but which is screwed through the bar BE, and the point of which, N, rests on the spring I. Now, if when we have applied the instrument to the forearm, the point D presses the lever A upward, with just sufficient force to bring the pen opposite the centre of the paper, we have no use for the screw; but if the point D does not quite reach the lever it is only necessary to turn the screw downward. The point N becomes fixed against the upper surface of the plate K, and the bar BD is carried upwards by the screw until the point D reaches the lever and raises the pen to the desired level. 01 of two portions: first, that by which the wave of blood in the artery is translated into the motion of the long arm of a lever; and second, that by which the Fig. 2 represents the entire instrument in position; and here the registering portion is shown. It consists of a perfectly smooth brass plate, XZ, to which a strip of glazed paper is fastened, and which is moved along, in the direction indicated by the arrows, by a little watch-work contained in the box S. The watchwork is wound up by turning the screw-head V, is set in motion by moving the lever G in one direction, and is stopped at will by moving it in the opposite direction. The motion of the watch-work is perfectly uniform, and the passage of the entire length of the plate past the pen, A, occupies ten seconds. Both of these figures are modified from woodcuts contained in Marey's Medical Physiology of the Circulation of the Blood. By changing the form of the frame the instrument can be adapted to any artery which lies sufficiently near the surface. This particular form, which is the most generally applicable at the bed-side, is intended for the radial, and is attached to the forearm by a tape passing backward and forward underneath the limb and over. hooks on the frame itself. This same instrument can, with a little management, be applied to the posterior tibial if any lesion-an aneurism of the popliteal, for. instance-renders it desirable. From the construction of the instrument it is evident that the trace is the result of the action of two forces. If the paper stood still and the lever alone moved, the pen would describe a short are of a circle, which for practical purposes may be considered as a vertical line. If the pen stood still and only the paper moved, the line described would be perfectly straight and horizontal. If the pen moves up and the paper moves forward with the same velocity, the trace will be a diagonal, making an angle of 45° with the horizontal; and so on ad infinitum. The more rapidly, then, any line ascends or descends, the more rapid must have been the ascent or descent of the pen, and the more sudden must have been the change in the tension of the artery. In Marey's instrument the short arm of the lever measures about one-twelfth of an inch, and the long arm rather more than five inches and a quarter; therefore, each variation in the pulse is magnified about sixty-five times. ITS HISTORY. idea of the character of a given pulse, we are no longer CHARACTER OF THE TRACE IN HEALTH. Fig. 1, in the accompanying lithograph, is copied from the trace of my own radial artery, taken in Aug., 1866, at which time I was in perfect health. Probably the most noticeable point to a person seeing a sphygmographic trace for the first time is, that with each beat of the heart we have the lever raised twice, which means that there are two pulsations in the radial artery -the second much weaker than the first, but nevertheless perfectly distinct. This phenomenon is called dichrotism, and the pulse is said to be dichrotic. The second beat is not always so well marked as in this Of the history of this instrument we can only say a case; but it exists almost universally in healthy perfew words. The first instrument for rendering the char- sons. Careful auscultation shows that there is only acter of the pulse more evident than it is to the sense one beat of the heart, though there are two pulsations of touch was the invention of Hérisson, and was called in the radial; and this latter phenomenon was at first the sphygmometer. In its essential points it was ex- accounted for by supposing that the second pulsation actly like the instrument which Dr. Hammond exhibited was due to the contraction of the aorta and large bloodsome weeks ago, designed to measure the pressure of vessels after they had been filled from the ventricle and blood in the brain. It consisted of a metallic cylinder the aortic valves had closed. The contractility of or drum, over the bottom of which was stretched an certain portions of the arterial system is a well-settled elastic membrane. To the top of the drum a cork was fact; but the rhythmic contractions of arteries never fitted through which ran a glass tube, and the instru- have the frequency of the heart-beat. To investigate ment was filled with mercury, which rose a certain dis- this subject, as well as many others connected with tance in the tube. The bottom of the instrument was the circulation of the blood, Marey constructed what placed over an artery, and with each pulsation the mer- he calls a schéma-an artificial heart and system of cury rose and fell in the tube. This instrument magni- blood-vessels-in which the arteries are replaced by fied the pulse considerably, but was open to two objec- simple, elastic, rubber tubes, and all the physical contions. The oscillations were due in a great degree to ditions of the organs of circulation are reproduced as the vis inertia of the heavy liquid when once set in mo- accurately as possible. With this schéma Marey obtion, and not solely to the motion of the blood in the ar- tained a perfectly dichrotic pulse-in fact in all essentery; and, in the second place, they were not recorded. tial points the trace was the same as that in the figure. Soon after this instrument appeared, it occurred to And, since rubber tubes are merely elastic and not conLudwig that it would be desirable to record the oscilla- tractile, he concludes, after a series of well-conducted tions of the mercury in Poisseuille's manometer. To experiments, that the phenomenon of dichrotism is effect this, a piece of light wire was driven into a wood-due to two causes: first, the acquired velocity of the en float, and the float was placed on the surface of column of blood thrown into the vessels by the venthe mercury. The wire was long enough to pass up tricle; and, second, the elasticity of the vessels, which through the tube and project above its open end, and, of causes the liquid column to oscillate alternately to and course, partook exactly of the motion of the mercury. fro." He afterwards proved, by experiment on a living It was then bent at right angles, armed with a pencil- horse, that at the instant when the second pulsation point, and made to trace a curve on a strip of paper is felt there is actually a backward flow through the moved by clock-work. This was an important step, be- artery. cause the instrument left an accurate, written trace of the oscillations of the mercury. Vierordt next made an effort to devise an instrument which should magnify the pulse, as did that of Hérisson, and should record it, as Ludwig's recorded the oscillations of the mercury in the manometer. He succeeded to a certain extent; but the objection to his instrument was that the long arm of the lever acquired a momentum from the impulse of the wave, which carried the pen far beyond the point to which the motion of the artery alone would have taken it. Marey, by making the lever of wood and aluminum, so as to be exceedingly light, and by using the spring, Y, instead of a weight, to keep it down, has avoided this source of error. It appears, then, that we have here an instrument which registers, with almost perfect accuracy, the character of the pulse, so that copies of it can be sent from place to place, or engraved to illustrate a text; that, in endeavoring to convey to another person an There are many variations in the amount of dichrotism. In senile ossification, when the arteries have lost their elasticity, we might expect that it would cease entirely; and so we find that it does. Both in health and in disease the number of rebounds may increase to three, four, or even five, under certain conditions. Fig. 2 is copied from the trace of a patient of mine who has aortic regurgitation, and it will be noticed that there are four distinct rebounds with each beat of the heart. In certain diseases-typhus fever, for instance-the pulse loses its dichrotism; and Dr. Grimshaw, in an article in No. LXXXV. of the Dublin Quarterly, makes the statement, based on some three thousand observations, that the first and surest sign of convalescence is the return of dichrotism. It will next, be noticed, in still further examining Fig. 1, that a line running along the tops of the curves would not be straight, but curved. It is evident that any cause which increases the tension in the radial artery while the instrument is applied to it will increase the diameter of the artery and raise the lever, and vice versa. If while the instrument is applied to the right arm the left arm be raised up quickly, the weight of the column of blood in that arm adds to the tension in the rest of the arterial system, and the lever rises. If a forced expiratory effort be made with the mouth and nares closed, the aorta will be compressed, together with the other contents of the thorax, the blood will be forced into the radial, the diameter of the artery will be increased, and the lever will rise. This is well shown in Fig. 3 taken from the radial of a friend under these circumstances. The same phenomenon is observed in coughing, in sneezing, and in a less degree in ordinary respiration. No pathological importance is to be attached, therefore, to the mere fact that the apices of the curves are not in the same straight line. A much greater importance is to be attached to the shape of the trace of each individual pulsation. To simplify the study of these they may be divided into three parts-a period of ascent, a summit, and a period of descent. The ascending line expresses, by its form and the angle which it makes with the horizontal line, the manner in which the blood enters the arterial system. If the ventricle is strong and the current meets with no opposition, the lever will rise almost instantaneously. If the arterial tension is considerable, the ventricle meets with more or less resistance in emptying itself, and the ascending line is more or less oblique. When it is sufficiently oblique we can always notice that it is a curve, showing that the pressure varies at different instants. The summit of the curve may vary from a sharp point to a perfect arc of a circle, and this part of the curve is always to be carefully scrutinized. In health a certain instant of time must always elapse during which the pressure of the ventricle and the resistance of the peripheral portion of the arterial system will nearly counterbalance each other. In disease, and especially in aortic insufficiency, as we shall see presently, the lever, light as it is, is carried up so rapidly as to fly past the point to which the increased diameter of the artery would carry it, and then returns almost in the same line, leaving a very sharp point. Immediately after the lever has reached its highest point the sigmoid valves close and the blood in the arteries is subject only to the effects of the elasticity and contractility of the coats of the arteries, under the influence of which it oozes into the venous system through the capillaries. If this takes place perfectly evenly the line of descent will be a regularly descending curve. The phenomenon of dichrotism which takes place in this portion of the curve we have already discussed. Having now gained some idea of the character of the curve in health, let us glance at a few traces taken in disease, see how they differ from that of health, and what these differences signify. SENILE CALCIFICATION OF THE ARTERIES. FIGS. 4 AND 5. In advanced life, before calcareous deposit actually occurs in the coats of the arteries, these coats lose their elasticity, and often more or less degeneration takes place. This change does not generally bring about any important derangement in the circulation, but seems to be a predisposing cause of cerebral hemorrhage, and is certainly sometimes followed by rupture of the large vessels. A positive detection of the disease will therefore be of considerable value in aiding a prognosis. This condition of the coats of the arteries is almost constantly accompanied by two other lesions, hypertrophy of the left ventricle and dilatation of the aorta and its immediate branches, both of which latter are the result of the former in this way. It is capable of demonstration that, with an intermittent flow, more fluid will run through an elastic tube than through a rigid one, both having the same diameter and the same pressure being applied in both cases. The loss of elasticity in the arterial coats requires, therefore, more energetic action on the part of the heart, and induces hypertrophy of the left ventricle. And the fact that the blood is thrown with greater force against vessels which have already lost their elasticity induces their dilatation. What we should naturally expect, under these circumstances, is that the ventricle would pour the blood rapidly at first into a vessel almost empty, and very slowly toward the end of the systole when the almost inextensible arteries were already nearly full; and since we have seen that dichrotism is in great part dependent on the elasticity of the arteries, we should expect it to disappear. This is precisely what we do find, as shown in the figures. The principal characteristics of the senile pulse, then, are the following: 1st, Great breadth of the trace; explained by the ventricular hypertrophy and the large volume and inelasticity of the artery. 2d, The ascent is rapid at first; because a powerful ventricle is emptying itself into a non-contractile vessel which has lost, through the capillaries, a great part of the fluid which it received with the last beat. 3d, The summit of the curve is rounded or flattened; the systole being prolonged because the aorta cannot stretch to receive the wave at once. 4th, The curve falls rapidly immediately after the flattened or level portion. This character is not constant, and is due to the fact that the sigmoid valves, after their closure, bulge more or less toward the ventricle, lowering the tension in all the arteries suddenly, though not to any very great degree. 5th, The almost constant absence of dichrotism; which has been already explained. COLLATERAL CIRCULATION. FIGS. 6, 7, AND 8. We all know that immediately after an artery has been tied in its continuity, no pulsation can be felt beyond the point of ligature, and that the parts are subsequently supplied with blood by enlargement of the anastomotic vessels. A certain amount of anxiety is always felt, lest gangrene should supervene, until we know that the collateral circulation is fully established, and the sphygmograph is the most certain meas of detecting this. Fig. 6 is the trace of the carotid pulse of a healthy horse. Immediately after this was taken the artery was ligated, and the instrument, applied immediately beyond the ligature, made the trace represented in Fig. 7, which, though excessively weak, is perfectly distinct. Ten minutes later the trace represented in Fig. 8 was obtained, and it shows with what rapidity the collateral circulation was gaining ground. It is worth while to remark that when Fig. 7 was taken no pulsation whatever could be detected by the finger, and precisely the same circumstance has been noticed in the radial artery of the human subject when the current of blood through the brachial artery had been stopped. ANEURISM OF THE ARTERY OF ONE OF THE EXTREMITIES. FIGS. 9-12, In this case we have a vessel of a given diameter opening into a large elastic pouch, from the opposite side of which goes out another vessel of the same diameter as the first. A moment's consideration will show us that this arrangement ought to act like the large receiver of a fire-engine, which receives the water from the pump in sudden jerks and sends it from the nozzle of the hose in nearly a steady stream. The elasticity of the air in the receiver has the same effect as the elastic coats of the aneurismal sac. In the affection which we are discussing, by comparing the traces from the two radial arteries in case of the upper extremity, or from the two posterior tibials in case of the lower, we find that this is precisely the result we have. In some cases the difference between the pulsations on the two sides can be felt; but in others it cannot, though the sphygmograph renders it evident. The case represented in Figs. 11 and 12 was curious in two respects; first, in the immense influence of respiration, caused by the patient's lying on his face when the trace was taken; and, second, in that the pulsation on the affected side could not be felt at all, though the trace is sufficiently clear. In every case the trace taken on a suspected tumor itself is almost perfectly pathognomonic. If it is really an aneurism the trace will be very wide, while if it is merely a tumor lying over an artery there will be no pulsation at all, or it will be simply a reproduction of the trace of the corresponding artery on the other side of the body, diminished in intensity. It has been pointed out that, in an aneurism of the kind we are discussing, the pulsation of the artery on the affected side will be slightly behind that on the side not affected. I am not aware that this had ever been explained until it was shown, by Marey's experiments, that the point of the lever commences to rise on both sides at the same instant; that on the healthy side the upward motion is sudden, and the pen reaches the highest point almost instantly, while on the affected side it rises slowly, and the highest point of the curve is reached only after the lapse of a very sensible period. Since the finger refers the moment of pulsation to the highest point of the curve, the pulsation on the affected side will, of course, appear to be a little behind the other. AORTIC ANEURISM. FIGS. 13 AND 14. One of the most reliable symptoms of this disease, aside from those which arise from the physical examination of a pulsating tumor in the chest, is the difference between the pulsations of the two radial arteries. In the case shown in Figs. 13 and 14 the finger could not detect any difference with certainty. This dissimilarity between the pulsations of the two radials is probably to be accounted for by the fact that the pormore involved than that from which the left subclavian is given off, or vice versa. tion of the arch from which the innominate arises is VALVULAR DISEASE. Lastly, we will consider briefly the diseases of the orifices of the heart itself. Many of the most interesting uses of the sphygmograph have not been touched upon in this paper, because they are purely physiological and because any comprehensible account of them would occupy far too much time. By a series of experiments which were in many respects original, and which were made with an instrument differing somewhat in form from this one, but constructed on the same principle, Marey was led to adopt the most generally received opinion with reference to the causes and order of succession of the heartsounds. The order is: the first sound accompanied by the stroke of the heart against the thoracic walls; a short silence; the second sound; a long silence. These four phenomena, taken together, coustitute a revolution of the heart. The first sound he attributes to three causes: first, the closure of the auriculo-ventricular valves; second, the sudden change in the form of the ventricle; and third, the contraction of the muscular walls of these cavities. The second sound is caused by the sudden closure, and consequent clacking, of the valves of the aorta and pulmonary artery. The two ventricles con tract perfectly simultaneously, and the valves of the aorta and pulmonary artery close at the same instant. Now it is not always easy in a diseased heart to fix each of these acts as it takes place; and although we know the point where, in a perfectly normal heart, each of the sounds ought to be heard most distinctly, yet this organ is liable to be hypertrophied or to be displaced by various causes. And, still further, a particular disease of a particular orifice does not always occur alone, but is frequently complicated by some other disease of the same orifice or by a disease of some other orifice. So that, in actual practice, an accurate diagnosis of a disease of the heart is often far from an easy task, and the introduction of any instrument which will assist us should be hailed with joy. Marey has often at the bed-side of a patient diagnosed the disease which affected his heart by the use of the sphygmograph alone; but that was only when some one else had made a diagnosis by auscultation, and one means served as a check upon the other; and it is in this way that the two means of making a diagnosis should assist and control each other. Each orifice of the heart is liable to two distinct kinds of disease. Its diameter may be diminished-there may be obstruction; the valves which close the orifice in health may be insufficient-there may be regurgitation, and these diseases may be combined in almost any way. Aortic obstruction. Fig. 15.-Let us begin with the aortic opening. If this be obstructed the wave of blood is impeded in leaving the ventricle, and we might expect to have the line of ascent of the lever a gentle curve; and since the coats of the aorta are elastic, the sudden impulse will be converted into a more equable pressure and the summit of the curve will be rounded. The shape of the trace is somewhat like that in ossification, because blood at the close of the systole, making the summits in both instances there is obstruction to the flow of of the two curves more or less alike; and there is often absence of dichrotism because the blood enters the arteries so slowly as not to give rise to a rebound. The two curves differ materially from each other in the shape of the first portion of the line of ascent, because it is not. It not unfrequently happens that these two in the one case the flow is obstructed and in the other diseases, aortic obstruction and senile calcification, occur together, and we have a trace which combines the characteristics of the two. Fig. 15 is the trace of a patient suffering with aortic obstruction. Insufficiency of the aortic valves, or aortic regurgitation, is almost invariably accompanied by hypertrophy of the left ventricle; and Corrigan long ago called attention to the very strong pulse which always accompanies this disease, attributing it to the strength of the ventricle. Marey's experiments show, however, that the pen does not rise much higher after rupture of the aortic valves of a horse than before; but they show distinctly that the reflux of blood into the ventricle lowers the tension in the arteries, that the lever falls to a much lower point, and that the absolute breadth of the trace is due to the fact that the pen starts from a point lower than normal, rather than that it reaches a point higher than normal. The trace of aortic insufficiency, Fig. 16, shows that the blood leaves the ventricle very rapidly, and that after the apex is reached the tension is again rapidly lowered. The prominent characteristic of this trace is the sharp-pointed apex which always accompanies this disease. If, in a given case, one were in doubt whether a blowing sound over the aortic valves accompanied the first sound of the heart or the second, or whether it continued through both-that is, whether it |