the internal jugular veins exert an important influence on the production of the murmur.

This portion of the vessel is intimately connected with the cervical fascia, so that its calibre remains constant.

If, now, the dimensions of the vein above or below this site are diminished, or increased, respectively, the adherent portion of the vessel becomes relatively dilated, or constricted, as the case may be, and these are the conditions for the formation of a fluid vein.

According to some writers a general contraction of the veins on a diminished quantity of blood in circulation is present in anæmia, while others suppose that these structures undergo relaxation from malnutrition and loss of tone. In either event the theory advanced above will explain the presence of a murmur over the internal jugular vein.

In some instances the adherent portion of the vein is normally somewhat pouched, and it may be that an alteration in the quality of the blood would, under these conditions, be sufficient to determine the formation of a fluid vein. It must be borne in mind, too, that diminished viscosity of the blood, and lessened peripheral resistance, play an important part in the production of hæmic

murmurs.

A venous hum is not present in all cases of anæmia, and the intensity of the murmur does not necessarily correspond with the degree of deterioration in the quality of the blood.

A bruit may also be heard over the longitudinal and lateral sinuses, and over the subclavian and other veins in cases of anæmia.

A continuous venous murmur, apart from anæmia, is occasionally heard on either side of the xiphoid cartilage, and has been ascribed to constriction of the inferior vena cava at its junction with the right auricle.

The murmur resembles the fitful blowing of wind through the rigging of a ship under bare poles.

In those exceedingly rare instances in which a communication is formed between the ascending aorta and superior vena cava, a murmur may be heard over the first or second right intercostal space an inch or more from the sternal edge, which bears a resemblance to the sound produced by a water-wheel in motion.

The continuous murmur which attends the establishment of a communication between the aorta and pulmonary artery, a very rare event, is heard best close to the left sternal edge, about the level of the second costal cartilage. The murmur heard under these circumstances, though continuous, is not uniform in intensity, but varies rhythmically with the balance of pressure in the two vessels.

CHAPTER IV

THE PULSE

Definition-Method of Production-Physical Examination of Pulse-Inspection -Palpation-Graphic Record or Sphygmogram—Instrumental Determination of the Blood Pressure.

FROM a clinical point of view the pulse is the alteration in the shape of an artery which obtains during the time that each wave of increased pressure, due to the heart's systole, passes along the vessel. The perception of the pulse rests on the visible and palpable displacement which the artery imparts to the media in contact with it, as each wave of increased pressure passes beneath the point of contact.

The pulse depends on

1. An alteration in the shape of the artery from the flattened to the cylindrical (Broadbent).

2. A slight expansion of the artery.

An artery is usually flattened by the tissues which overlie it, and exercise pressure against some underlying and resistant medium. In the case of the radial artery it is the radius against which the vessel is pressed. The artery is still further flattened by the examining finger. All elastic tubes, however, tend to become circular when the fluid pressure within them is sufficient to overcome the resistances which conduce to alterations in their shape. Thus it is that as the pulse wave passes any particular point in the course of an artery, the vessel's shape is altered from the flattened to the circular, and a false impression of expansion is experienced. In addition to this factor in the production of the pulse the arterial wall does actually expand, but, in the case of the radial artery, to an extent which could scarcely be appreciated by the finger.

The physical examination of the pulse includes―

1. Inspection

2. Palpation

3. Graphic record or sphygmogram

4. The instrumental determination of the blood

pressure.

INSPECTION.

The information derived from inspection of the pulse is always checked by subsequent palpation. Nevertheless this method of investigation has its value as a means of rapid diagnosis. The vessels which lend themselves most readily to this mode of examination are the temporal arteries, and occasionally the retinal arteries, since the course of these vessels can usually be seen in the adult by careful inspection. The degree of tortuosity of the artery, and the frequency, regularity, and to some extent the character of the pulse, as well as the bilateral symmetry of the pulsation, can be roughly gauged. Thus aortic regurgitation may be suspected in cases where the discursion of the pulse is extensive, the collapse of the pulse wave sudden, and the vessels tortuous. Heart failure, especially in mitral regurgitation, is suggested by inequalities in the force and rhythm of the visible pulse. Visible pulsation of the carotid arteries is frequently associated with aortic regurgitation, and also with exophthalmic goitre and other nervous disorders of the heart. Other points, which may be observed on inspection, have their diagnostic value as described under palpation of the pulse.

PALPATION

Method of Feeling the Pulse

The first three fingers should be placed lightly upon the radial artery at the wrist, with the forefinger nearest the heart and the thumb supporting the wrist. The vessel should be investigated, under varying degrees of pressure, both in its transverse and longitudinal aspects, and each feature of the pulse that requires attention should be appreciated by a distinct and well-defined manoeuvre of the examining fingers.

The features of the pulse to which the observer's attention should be directed are the following :

1. The frequency. While counting the pulse rate, the regularity or irregularity of the force and rhythm of the pulse should also be observed.

2. The size of the artery.

3. The degree of fulness of the artery between the pulsations.

4. The character of the pulse wave.

5. The compressibility of the vessel.

6. The condition of the arterial wall.

7. The bilateral symmetry of the pulsations.

1. The frequency of the pulse.-The rate of the pulse and of the heart beats usually correspond; but this is not always the case, inasmuch as the force of the cardiac systole may not be sufficient to propel the pulse wave as far as the radial artery. The average

rate of the pulse in the adult male is about seventy-two beats per minute.

The conditions which give rise to physiological variations in the frequency of the pulse are: (1) Age, i.e. the pulse rate is quicker in children than in adults; (2) Sex, i.e. the pulse rate is quicker in women than men; (3) Heredity; (4) Nervous impressions ; (5) Emotional disturbance; (6) Exertion; (7) Position; (8) Food; (9) Temperature; (10) Time of day or night; (11) Alterations in blood pressure, etc.

The pulse rate is also influenced by drugs, such as alcohol, tobacco, digitalis, and the like.

The variations in the pulse rate produced by disease may be tabulated as follow:

A. Increased Frequency of the Pulse

(1) Pyrexia. (2) Anæmia. (3) Pathological conditions which decrease blood pressure. (4) Pericarditis. (5) Myocarditis. (6) Valvular disease of the heart. (7) Dilatation of the heart. (8) Irritable heart (Da Costa). (9) Loss of vagus control, or irritation of the cervical sympathetic (accelerator) nerves as observed in cases of palpitation, ex-ophthalmic goitre, etc. (10) Tachycardia. (11) Hysteria.

B. Diminished Frequency of the Pulse

(1) Renal disease. (2) Pathological conditions which increase blood pressure. (3) Jaundice. (4) Fatty and occasionally fibroid disease of the heart (the pulse rate is, however, sometimes increased under these circumstances). (5) Epilepsy and other cerebral disorders. (6) Pain. (7) During convalescence from the acute fevers, such as pneumonia, typhoid, etc.

The diminished frequency of the pulse that is found in association with the remarkable condition in which two beats of the heart occur to one of the pulse is of course not included in the present category. The condition is mentioned here with the object of. emphasizing the necessity of controlling observations made with respect to the frequency of the pulse at the wrist by an examination of the heart.

Rhythm

The rhythm of the pulse and of the heart's action usually correspond, but, as in the condition just mentioned, this is not necessarily the case.

Deviations from the normal rhythm give rise either to "intermittence" or to "irregularity" of the pulse, or to a combination of these conditions.

Intermittence of the pulse means the omission of a beat, which may occur at regular or irregular intervals. The phenomenon is more commonly observed in old than in young people, and it is fre

quently found independent of any other discoverable abnormality. It is habitual in some individuals, while in others it is readily produced by emotional disturbance, indigestion, or the abuse of tea and tobacco. Intermittence of the pulse is also observed in association with gouty manifestations. It is sometimes found in connection with fatty disease of the heart, with cardiac failure, and with acute affections of the lungs, and is then of serious import. It is said that habitual intermittence of the pulse usually disappears during attacks of pyrexia.

Irregularity of the pulse usually, but not necessarily, implies inequalities in the force and volume of the pulsations, as well as the appearance of the beats at unequal intervals of time. It is associated with valvular disease of the heart, and more especially with mitral regurgitation. It is also commonly observed in connection with failure of the heart from any cause, and speaking generally, it is a sign of disturbance of myocardial metabolism. Irregularity of the pulse sometimes depends on reflex disturbance of the heart from gastro-intestinal and uterine disorders. It also occurs in association with the abuse of tea, coffee, and tobacco. It is occasionally found. apart from any other morbid manifestations.

Certain peculiar modifications in the rhythm of the pulse are designated under the special titles of the pulsus bigeminus, the pulsus trigeminus, the pulsus alternans, and the pulsus paradoxus.

Pulsus bigeminus.—In this variety of pulse the beats are grouped in pairs, with a pause between each group. The second beat is usually the weaker of the two. The heart beats correspond in rhythm with the pulse, so that a strong impulse is followed by a weak one. This variety of pulse is found most commonly in mitral stenosis, more especially when under the influence of digitalis. It is also observed in association with bodily and mental strain and with epileptiform attacks.

Pulsus trigeminus.-In this variety of pulse the beats are arranged in groups of three. It occurs under conditions similar to those in which the pulsus bigeminus is observed.

Pulsus alternans-The regular succession of a strong and weak pulsation constitutes the pulsus alternans, which is observed in connection with Cheyne-Stokes' respiration, (Sansom) and with the other conditions of central nervous disturbance, and occasionally also with mitral affections.

Pulsus paradoxus. In this condition the pulse is markedly influenced by the respiratory movements. During inspiration the pulse wave is annulled, or becomes much diminished in force, while during expiration it may be of full amplitude. It can sometimes be elicited under physiological conditions by holding the breath in extreme inspiration or expiration. In certain pathological conditions, however, it is more or less constantly present. It occurs in association with pericardial adhesions, mitral stenosis, emphysema, and with conditions of heart failure.