This second sound of the heart consists of a single element only – a valvular element – in this respect differing from the first sound.
The first sound of the heart, as heard over the apex of the organ, is a mixed sound. It is composed chiefly of two distinct elements. One of these elements consists of a clicking sound, emanating from the mitral and tricuspid valves; the other proceeds from the movements of the apex of the heart against the thoracic walls. The latter is called the element of impulse, or the impulse-sound; the former, the valvular element, or valvular sound.
THE ABNORMAL SOUNDS OF THE HEART.
There are certain morbid sounds or murmurs of the heart which occur in disordered conditions of that organ. They mingle with, follow, or quite supersede the healthy sounds.
These “murmurs,” as they are generally called, with one or two exceptions may be considered as modifications of the bellows murmur, or bruit de souffle.
This, in its purest form, is a smooth, blowing sound, named from its resemblance to that made by a pair of bellows. It may be single or double, soft or loud, of a low or high key; short, so as to merely prolong one of the natural sounds, or continuous, so as to fill up more or less completely the space between the impulses. Sometimes it wholly supersedes the healthy sound, and nothing is heard but one continuous bellows-murmur; but such cases are rare.
Not unfrequently it becomes, in various degrees, rough or broken; and attempts have been made to designate the modifications thus produced by the terms filing, rasping, sawing, etc. The sawing sound being a double sound, should only be applied to the double murmurs produced by the alternate motion of the heart. In some instances the murmur is of a musical or whistling character, and has been compared to the chirping of young birds.
The pure bellows murmur may exist without any organic disease of the heart. It may be produced artificially, by alternations in the diameter of one of the larger arteries, even in health, as by the pressure of the stethoscope upon the artery. The most frequent cause of the sound is probably an abrupt contraction at one of the orifices, or in one of the tubes through which the blood passes. It will be readily understood that the fluid, as it emerges from the stricture, and spreads out to fill the larger space beyond it, breaks into currents, which set against the sides of the tube, and, being thence reflected, occasion vibrations which result in sound. Thus the sound may result from contraction of any of the orifices of the heart, or the expansion of one of the great arteries immediately beyond them, and, in the former case, may be produced either by organic or by functional disease or spasmodic contraction. The bellows murmur is not always produced by changes in the heart and arteries. It may be produced by a watery state of the blood, and such as occurs in chlorosis or anaemia. The liquid in these states being more movable, currents are more easily formed by whatever effects the regular movements of the blood. In such conditions, anything which excites the circulation will generate the murmur. It may also be induced by bleeding, and arises from any profuse haemorrhage.
The rough murmurs, as they are called, to distinguish them from smooth murmurs, may be produced by inequalities in the surface over which the blood flows, especially in the orifices of the great vessels, produced by depositions of lymph, excrescences of various kinds, osseous or cartilagenous productions, etc. These rough sounds, like rasping, filing, and the like, are supposed to indicate organic disease in the valves or the valvular openings.
Another species of murmur is called the regurgitant. These regurgitant murmurs are caused by some defect in the valves – either loss of substance, irregular thickening, dilatation of the orifice, or something else which prevents their accurate closure, and thus allows a regurgitation of the blood. It may be supposed that in these cases the sound is ascribable not only to the irregularity given to its backward movement through the insufficient valve, but also in some measure to the conflict of the reverted with the regular current of blood; as, for example, when the blood of the contracting ventricle is sent through the insufficient auriculo ventricular valve against the current entering the auricle.
All these murmurs are heard most distinctly when the heart is in an excited condition. They are influenced by the less or greater force of the moving cause. the systolic ventricular murmurs are louder than the diastolic, because the former is caused by the more powerful contraction of the ventricles; the latter, on the feebler elastic pressure of the great arteries.
Roughness of sound is proportionate to irregularity in the surface producing it, and it most frequently attends regurgitation.
The tone of the murmur depends somewhat on the depth at which the sound is generated.
By close examination, the following two important points can be ascertained:
I. In which of the valvular orifices the murmur originated.
II. Whether it depends on obstructions, or upon deficiency of the valves, and consequent regurgitation.
When the sound is loudest on the sternum immediately below the insertion of the third rib, and thence extends upwards for about two inches along the course of the great vessels, it may be considered as having its source in the semi-lunar valves.
If the sound be perceived most distinctly along the course of the ascending aorta, upon the right, it is probably seated in the aortic valves; if along the pulmonary artery, on the left, it is in the pulmonic valves.
When the murmur is most distinct over that part of the chest on which percussion is dull – that is, where the ventricles are in contact with the walls – it may be inferred that it is generated either in the mitral or tricuspid valve; in the former, when the point of greatest loudness is a little to the right of the left nipple, and an inch or so below it; in the latter, when the analogous point is on or near the sternum, in the same horizontal line.
There are other morbid sounds, resembling murmurs, which have nothing to do with the valves of the heart.
Among these are the anaemic murmurs, mentioned above. They do not follow the course of the large vessels so fully or frequently as do valvular murmurs. They occur only during the systole of the ventricles – are not generally heard below the left nipple, as they do not arise form regurgitation through the mitral valve. They are almost always accompanied by a smart, smacking impulse. They disappear during mental or physical quiet. They are always diminished, and generally disappear under appropriate medical treatment, which is not ordinarily the case with true valvular murmurs.
Venous murmurs (nun’s murmur, top murmur,) are heard in many young persons, in the anterior triangular space, in which the external jugular vein descends. It is a continuous murmur, and is generally more audible on the right than on the left side. This murmur disappears when the current of blood is interrupted by pressure upon the jugular vein, or by any position of the body in which the head lies lower than the thorax. It is heard loudest in an erect position, and during inspiration. It was thought to be connected with anaemia, but has been found as often in young and healthy persons.
Pericardial murmurs. The inner surface of the pericardium is normally smooth, and the heart moves within it without causing any sound. But when this surface becomes roughened in consequence of inflammation and exudation, we hear friction-sound, which may closely resemble an endocardial murmur. We can generally distinguish between these murmurs, for the internal murmurs correspond almost exactly to the rhythm and the natural sounds of the heart, whilst the friction-sounds seem to follow upon the movements of the heart. Should the friction-sound be short, we cannot distinguish it from an endocardial murmur.
There is another friction-sound, caused by a roughened condition of that portion of the pleura which covers the unattached portion of the pericardium. It is produced by the rubbing of this portion of the pleura against the lungs or thoracic walls. Being caused by the action of the heart, it exactly coincides with its rhythm, and cannot be distinguished from endocardial murmurs. The previous history of the disease and the result of appropriate treatment can only settle the question.
Hale wrote Lectures On Diseases Of The Heart, Materia medica and special therapeutics of the new remedies Volume 1, Materia Medica And Special Therapeutics Of The New Remedies Volume 2, Saw Palmetto: (Sabal Serrulata. Serenoa Serrulata), The Medical, Surgical, and Hygienic Treatment of Diseases of Women, New Remedies: Their Pathogenetic Effects and Therapeutic Application, Ilex Cassine : the aboriginal North American tea, Repertory to the New Remedies with Charles Porter Hart, The Characteristics of the New Remedies, Materia Medica and Special Therapeutics of the New Remedies, The Practice of Medicine, Homoeopathic Materia Medica of the New Remedies: Their Botanical Description etc.