Undulatory movement, in strict language, is only produced when the peri cardium is fall of serum; a largely dilated heart merely simulates it: in the one a wave is transmitted from the apex towards the distended upper extremity of the sac, at each systole ; in the other, different portions of the organ come in contact with the chest in succession, but the definite course of a wave can not be traced : the one occurs daring as acute attack, the other is seen in chronic disease.
Irregularity is best recognised by the action of the pulse : by it the meaning of the term intermission is also more readily understood; the abortive con traction of the heart produces no pulsation at the wrist, and a beat is lost just as much as if the heart stood still. The word " nueven" is used to signify a pulse of unequal force: an irregular pulse implies inequality in the duration as well as in the force of successive beats. Irregular action may subside under treatment, but during' its existence it is a permanent, not a temporary condition; hence we speak of continued irregularity as a sign of disease.
The extension of dulness tovrards the sternum can only deceive when there is a morbid growth in the anterior mediastinum : the dulness in such a case does not usually terminate on a level with the base of the heart. It is of im portance to observe whether the apex continue to beat in its usual position, lest displacement be mistaken for enlargement.
In endeavoring to establish correct rules for diagnosis, it has been our constant aim to avoid taking solitary indications, how ever definite in themselves, as specific signs of any one form of dise,ase. This rule must be applied to the varieties of pulse ob served in disease of the heart, which shall be enumerated as they present themselves to our notice in considering the sum of the evidence in each case. It is also applicable to the suggestion of adherent pericardium above referred to, and to the angular or pear-shape which we may find the prfecordial dulness to have assumed when dependent on hydro-pericardium ; no one who studies diagnosis aright will suppose the existence of such a con dition, unlen acute symptoms have preceded it ; passive effusion is never sufficiently extensive to produce the effect If we commence with irregularity of action as one of the most evident signs of disease, we find in practice that it may coincide with the other phenomena already enumerated in very varying degrees, and from a consideration of these associations the follow ing conclusions may be drawn as probable explanations of the condition of the heart.
a. With increased heaving impulse we may &ssume the exist ence of hypertrophy with or without valvular lesion.
b. Without increased impulse, but with extended dulness, en largement consisting especially in dilatation of the cavities, while the walls are not much thickened, or may be even thinner than natural; and again either with or without valvular lesion.
c. When abnormal sound is heard, we may be pretty certain that there is valvular insufficiency along with either hypertrophy or dilatation, as the other indications tend to show.
d. A very feeble pulse, with signs of hypertrophy, would afford very clear evidence of imperfect closure of the mitral valve.
e. When none of these conditions accompany the irregularity, we may be led to believe that it is due to thinning of the walls of fatty degeneration without dilatation to any extent ; it may possibly be also caused by adherent pericardium.
Irregular action seldom accompanies hypertrophy without valvular lesion ; whereas it is most commonly present in dilatation and thinning of the walls whether the valves be healthy or not. The character of the pulse varies with the peculiar form of the valvular lesion, but in most instances the morbid sound heard on auscultation is more trustworthy : it now and then happens, however, that when the mitral orifice does not close during the systole, no bruit can be detected ; and then the extreme feebleness of the pulse, contrast, big with the force of the heart's action, serves as a very useful gaide. When valvular lesion has not led to alteration in size, it is not accompanied by irregularity of action.
It must also be borne in mind that very considerable hypertrophy may be almost completely concealed by overlapping of the lung, sad therefore peat caution must be exercised in deciding that irregular action depends on simple atrophy or fatty degeneration. Each of these subjects will be again referred to more in detail.
When there is no irregularity, the only trustworthy indications of enlargement are a. If increased action be associated either with extension of dulness in an inward direction or with an apex-beat lower than in health ; b. If with the increased action or the extended dulness there be anything of an undulatory movement, and especially if this be accompanied by some unusual sound on auscultation.