But palpation further teaches us that disease of the heart itself may not only not augment, but may even lessen the force of the cardiac impulse to a degree which is readily appreciated by the hand. Thus, atrophy, or softening, or dilatation of the heart, may weaken its force or even render it unappreciable, and so may extensive effusion into the pericardium.

Palpation also enables us to recognise amazing differences in the character of the impulse. The shock may be abnormally sharp, abrupt, or jerking, or, on the contrary, unusually slow and heaving. The former character results from weakness and irritability; the latter, if temporary, from functional disturbance, or, if permanent, from hypertrophy. The character of aneurismal impulse is extremely variable; but it may become so forcible, and yet so abrupt, as to convey the idea. of hammering, in which case it may almost be regarded as characteristic of the disorder.

*

Further, the hand appreciates variations in the rhythm of the impulse. Not only may it make us aware of the double impulse which is sometimes felt towards the apex of the heart, and which has been already described, but it leads us to recognise irregularity in the force with which and the time at which the successive pulsations take place. Thus it sometimes teaches us that the successive impulses of the heart, instead of being equidistant from each other in point of time, and identical or nearly so in force, are most unequal in force, and extremely irregular in the time of their occurrence. One stroke may be forcible and the next weak, or the number either of the strong and feeble impulses, or of both, may vary indefinitely. And so also in respect to the time at which the successive impulses take place. Three or four in succession may be equidistant from each other, and these may be succeeded by an indefinite number, each succeeding the preceding one at a different interval of time, until in some instances a distinct intermission of one or more pulsations may be perceived.

The causes of the irregularity in point of time are closely connected with those which occasion irregularity of force; for the one form of irregularity is seldom observed without the other. Both the one and the other are often met with in functional palpitation, when no disease of the heart exists, and also in cases of hydrocephalus, pericarditis, and other acute disorders. In these cases, the causes of irregularity being of temporary duration, the irregularity itself is only *Vide ante, pp. 8, 10.

temporary. The lesions which are specially prone to occasion permanent irregularity of force are regurgitant disease of the mitral valve, and a similar affection of the aortic valves; whilst simple dilatation and fatty degeneration and flabbiness of the heart are specially productive of irregularity of rhythm. Malformations of the heart are apt to produce perversion both in the rhythm and force of the pulse; but this is not the case with simple hypertrophy of the ventricles, nor with obstructive disease of the aortic valves.

There are other phenomena, of an adventitious character, of which palpitation also takes cognizance. I allude to "friction thrill," caused by attrition of the inflamed and roughened surfaces of the pericardium, and to a peculiar "purring tremor," or thrill, caused by the forcible propulsion of the blood through orifices narrowed and roughened by disease of the valves, or through vessels roughened by atheromatous deposits, or affected with aneurismal dilatation; or, in some instances, by the irregular action of the heart or great vessels, induced by perverted innervation and a morbid condition of the blood, independently of valvular or arterial mischief. The valvular thrill being referable to an eddy produced by the forcible propulsion of blood through a roughened orifice, may diminish in intensity, or even cease altogether when the heart's action is weak and failing, and when the contraction of the orifice becomes excessive—in both of which cases the current of the blood may cease to be sufficiently full and strong to produce an eddy capable of imparting a thrill to the chest walls. In like manner, the aneurismal thrill may diminish, or even cease, if the heart's action becomes feeble, or if the aneurismal pouch becomes filled with smooth coagula of fibrin. In the rare and exceptional cases in which parietal thrill is caused by perverted cardiac action, dependent solely on perverted innervation, and a spanæmic condition of the blood, the thrill, from its nature, is necessarily of temporary duration; whereas, when due to aneurism or valvular disease, it is usually a persistent phenomenon. When occurring as the result of perverted innervation, and an altered condition of the blood, it may be felt over the entire surface of the chest, and especially over the pulmonary artery in the second left intercostal space. When due to aneurismal dilatation, it varies in position with the seat of the aneurismal tumour; and when referable to valvular disease, it varies in position according as one valve or the other is affected. The most common cause of valvular thrill is regurgitant disease of the mitral valve, occurring coincidently with hypertrophy of the left ventricle, in

which case the thrill is felt principally in the third, fourth, and fifth left intercostal spaces, where the position of the lung enables the heart to come into apposition with the chest walls; but I have also felt it on two occasions in connection with extensive regurgitant disease of the aortic valves; the only other cause of it* is aortic obstruction, with hypertrophy of the ventricle, in which case the thrill is felt in the track of the aorta, and even somewhat beyond its limits; or, in other words, in the third left, and second and third right intercostal spaces, close to the sternum.

Aneurism is, perhaps, the most frequent cause of purring thrill, and the phenomenon is usually more strongly developed than in cases of mere valvular mischief. In all cases in which a thrill exists, a spanæmic condition of the blood adds greatly to its intensity.

Pericardial friction thrill is comparatively rare, and, when perceptible during the diastole as well as during the systole of the heart, is confined, as I believe, to cases in which the outer layer of the pericardium is adherent to the anterior of the chest by lymph effused in the anterior mediastinum.† The sensation which it conveys to the hand is very similar to that produced by endocardial thrill; but, although sometimes synchronous with the systole of the heart, it usually accompanies the greater part of the heart's action. It frequently shifts its position, and is felt over a large extent of surface-facts which suffice to distinguish it from valvular thrill.

Hypertrophy and dilatation of the heart may cause widening of the intercostal spaces, and effusion into the pericardium may give rise to bulging of the spaces, as already described; and these facts, and also the absence of vocal vibration over the surface occupied by the enlarged and dilated heart or distended pericardium, will be readily detected by the hand.

Palpation gives us little information respecting the condition of the thoracic aorta in a state of health. If the finger be placed above the sternal notch, and pressed down behind the sternum, as far as possible

* It is conceivable that obstructive disease of the mitral valve might give rise to its occurrence, or, again, that it might arise from disease in the tricuspid and pulmonary valves. But experience does not give its warrant for the supposition, and I believe the statement above made to be strictly correct.

†This at least is certain, that this condition of the parts existed in the only seven cases in which I have ever had the opportunity of verifying the observation by inspection after death.

See p. 6 of this treatise.

towards the aorta, the pulsations of the vessel may generally be felt, but in no other position does palpation even make us aware of their existence. It affords us, however, important assistance in an examination of the large vessels of the neck and other parts of the body. It tells us of an undulatory, expansile movement, which is referable to the diastole of the artery, and corresponds to each ventricular systole, and of a contraction or systole of the vessel corresponding to each diastole of the ventricles; it shows, that in the vessels near to the heart the diastole and systole are respectively coincident in point of time with the systole and diastole of the ventricles; but that, in the radial artery, and in other vessels more distant from the centre of circulation, each movement of the arteries is somewhat behind its corresponding movement in the heart, so that the radial pulse is not quite synchronous with the systole of the ventricles.* Further, it informs us of abnormal pulsation in the vessels, referable to functional derangement of the system, and also of variations in the pulse occasioned by disease in the heart and in the coats of the vessels. Thus we learn that the pulse may be quick or slow, soft or hard, small or large, weak or strong, regular or irregular in force, and other characters-intermittent, jerking, thrilling, fluttering, or bounding-each of which conditions may be indicative of disease, though not necessarily connected with any special form of mischief. Arterial thrill, as contrasted with thrill communicated to the chest walls, may originate in an altered condition of the aortic valves, or of the aorta itself, or of the blood and of the nerves supplying the vessels. Thus a peculiar thrill, resulting from aortic obstruction or aortic regurgitation, may be sometimes felt in the larger vessels all over the body; simple dilatation of the aorta, with roughening of its internal surface from atheromatous or calcified deposits on its coats, is another frequent cause of arterial thrill, and so is irregular contraction of the vessel, dependent on perverted innervation, combined with an impoverished spanæmic blood.

When there is pulsation in the jugular or other large veins, palpation may discover a soft thrill in the veins somewhat resembling an arterial thrill. This is not always, nay it is not generally present in these cases, nor has it hitherto been traced to any special form of disease. So far as is known at present it simply denotes the existence of excessive regurgitation, producing more than ordinarily forcible vibration.

* This may be admirably demonstrated by the aid of Dr. S. Alison's sphygmo

scope.

CHAPTER IV.

PERCUSSION.

In the section devoted to the topography of the heart and great vessels, attention has been drawn to the relations which these organs bear to the chest walls, and to the surrounding structures. are, therefore, in a position to form an opinion as to the sound which should be elicited by percussion of the præcordial region in a state of health, and to judge of the deviations in the character of that sound which are likely to be produced by various forms of disease. In practice, however, many complications occur which would not suggest themselves to the unpractised examiner, and it may be advisable, therefore, to consider the subject in detail, rather than allow the sounds which arise to remain a matter of inference.

In the first place, it may be stated, that even in a state of health, considerable difficulty is necessarily experienced in determining accurately the size and position of the heart. The constant action of the organ, involving, as it does, perpetual change in its form and position; the incessant alterations induced by respiration in the position of the lungs ; the ever-changing resonance elicited over the ribs and sternum at different stages of the respiratory act; and the proximity of the great vessels above and of the liver below-present obstacles to an accurate determination of its outlines which cannot be readily overcome. Therefore, when an attempt is made to determine by percussion the size and position of the heart and great vessels, every care must be taken to ensure a satisfactory result.

The patient should be placed in a recumbent posture, and gentle as well as forcible percussion should be practised. Gentle percussion will bring out the resonance of any lung tissue lying between the heart and the chest walls, whilst a more forcible stroke will elicit the dull sound caused by the presence of the heart behind.

Further, the intercostal spaces, as well as the ribs and sternum, should be percussed; for when the bony structures receive the impulse, it is communicated in some degree to the adjacent lungs, and a clearer resonance is elicited than would be yielded by the structures