tion which operates upwards and downwards, and occurs in the period between
the regular contraction and the twitching vibratory movement.
48. The Movements of the Heart.
Cardiac Revolution. The movement of the heart is characterised by
an alternate contraction and relaxation of the cardiac walls. The
total cardiac movement is called a " CARDIAC REVOLUTION," or a
" cardiac cycle," and consists of three acts the contraction or systole
of the auricles, the contraction or systole of the ventricles, and the pause.
During the pause the auricles and ventricles are relaxed ; during the
contraction of the auricles the ventricles are at rest; whilst during
the contraction of the ventricles, the auricles are relaxed. The rest
during the phase of relaxation is called the diastole. The following
is the sequence of events in the heart during a cardiac revolution :
EVENTS DURING A CARDIAC REVOLUTION.
(A.) The Blood Flows into the Auricles, and thus distends them and
the auricular appendages. This is caused by
(1.) The pressure of the blood in the venae cavse (right side) and the
pulmonary veins (left side) being greater than the pressure in the
(2.) The elastic traction of the lungs ( 60) which, after complete
systole of the auricles, pulls asunder the now relaxed and yielding
auricular walls. The auricular appendages are also filled at the
same time, and they act to a certain extent as accessory reservoirs
for the large supply of blood streaming into the auricles.
(B.) The Auricles Contract, and we observe in rapid succession
(1.) The contraction and emptying of the auricular appendix
towards the atrium. Simultaneously the mouths of the veins become
narrowed (Haller, Nysten) owing to the contraction of their circular
muscular fibres (more especially the superior vena cava and the
(2.) The auricular walls contract simultaneously towards the auriculo-
ventricular valves and the venous orifices, whereby
EVENTS DURING A CARDIAC CYCLE.
(3.) The blood is driven into the relaxed ventricles, which are con-
siderably distended thereby.
The contraction of the auricles is followed by
(a.) A slight stagnation of the blood in the large venous trunks, as
can be easily observed in a rabbit after division of the pectoral muscles
so as to expose the junction of the jugular with the subclavian vein.
There is no proper regurgitation of the blood, but only a partial
interruption of the inflow into the auricles, because, as already men-
tioned, the mouths of the veins are contracted, and because the
pressure in the superior vena cava and in the pulmonary veins soon
holds in equilibrium any reflux of blood; and lastly, because any reflux
Gypsuin cast of the ventricles of the human heart viewed from behind and above;
the walls have been removed, and only the fibrous rings and the auriculo-
ventricular valves are retained L, left, R, right ventricle; S, position of
septum; F, left fibrous ring, with mitral valve closed; D, right fibrous ring,
with tricuspid closed ; A, aorta, with the left (Ci) and right (C) coronary
arteries ; S, siuus of valsalva ; P, pulmonary artery.
78 EVENTS DURING A CARDIAC CYCLE.
into the cardiac veins is prevented by valves. The movement of the
heart causes a regular pulsatile phenomenon in the blood of the vense
cavse, which under abormal circumstances may produce a venous pulse
(see Venous pulse).
(&.) The chief motor effect of the contraction of the auricles is the
dilatation of the relaxed ventricle, which has already been dilated to a
slight extent by the elastic force of the lungs.
The dilatation of the ventricles has been ascribed to the elasticity of the
muscular walls the strongly contracted ventricular walls (like a compressed india-
rubber bag), in virtue of their elasticity, are supposed to return to their normal
resting form, and thereby to suck in or aspirate the blood under a negative pres-
sure. Such suction power on the part of the ventricle is, however, only effective
to a very slight extent.
(c.) When the ventricles are distended by the inflowing blood, the
auriculo-ventricular valves are floated up, partly by the recoil or
reflexion of the blood from the ventricular wall, and partly owing to
their lighter specific gravity, whereby they easily float into a more or
less horizontal position. The valves are also raised to a slight extent
by the longitudinal muscular fibres, which pass from the auricles into
the cusps of the valve (Paladino).
(C.) The Ventricles now Contract, and simultaneously the auricles
(1.) The muscular walls contract forcibly from all sides, and thus
diminish the ventricular cavity.
(2.) The blood is at once pressed against the under-surface of the
auriculo-ventricular valves, whose curved margins are opposed to each
other like teeth, and are pressed hermetically against each other (Sand-
borg and Worm Miiller). It is impossible for the blood to push the
cusps backwards into the auricle, as the chordae tendinice hold fast their
margins and surfaces like a taut sail. The margins of the neighbouring
cusps are also kept in apposition by the
chordae tendiniae from one papillary muscle
always passing to the adjoining edges of
two cusps (John Reid). The extent to
which the ventricular wall is shortened is
compensated by the contraction of the
papillary muscle, and also of the large
muscular chordae, so that the cusps cannot
be pushed into the auricle.
pig, 24. " When the valves are closed their surfaces
The closed semi-lunar are horizontal, so that even when the
valves of the pulmonary ventricles are contracted to their greatest
artery seen from below. extentj ft small amount of Uood remainSj
which is not expelled (Sandborg and Worm Miiller).
PATHOLOGICAL DISTURBANCES OF CARDIAC ACTION. 79
(3.) Opening of the Semi-lunar Valves. When the pressure within
the ventricle exceeds that in the arteries, the semi-lunar valves are
forced open and stretched like a sail across the pocket-like sinus,
without, however, being firmly or directly applied to the wall of the
arteries (pulmonary and aorta), and thus the blood enters the arteries.
Negative Pressure in the Ventricle. Goltz and Gaule found that there was
a negative pressure of 23 '5 mm. Hg. (dog) in the interior of the ventricle during a
certain phase of the heart's action. They surmised that that phase coincided with
the diastolic dilatation, for which they assumed a considerable power of aspiration.
Marey observed a similar condition and called it " vacuite postsystolique," but
thought that it coincided with the end of the systole; while Moens is of opinion that
this negative pressure within the ventricle obtains shortly before the systole has
reached its height, i.e., just before the inner surface of the ventricles and the
valves, after the blood is expelled, are nearly in apposition. He explains this
aspiration as being due to the formation of an empty space in the ventricle caused
by the energetic expulsion of the blood through the aorta and pulmonary artery.
(D.) Pause. As soon as the ventricular contraction ends, and the
ventricles begin to relax, the semi-lunar valves close. The diastole of
the ventricles is followed by the PAUSE. Under normal circumstances
the right and left halves of the heart always contract or relax uni-
formly and simultaneously.
49. Pathological Disturbances of Cardiac Action.
Cardiac Hypertrophy. All RESISTANCES to the movement of the blood
through the various compartments of the heart, and through the vessels com-
municating with it, cause a greater amount of work to be thrown upon the
portion of the heart specially related to this part of the circulatory system ; con-
sequently, there is produced an increase in the thickness of the muscular walls
and dilatation of the heart. If the resistance or obstacle does not act upon
one part of the heart alone, but on parts lying in the onward direction of the
blood-stream, these parts also subsequently undergo hypertrophy. If in addi-
tion to the muscular thickening of a part of the heart the cavity is simultaneously
dilated, it is spoken of as eccentric hypertrophy or hypertrophy with dilatation.
The obstacles most likely to occur in the blood-vessels are narrowing of the
lumen or want of elasticity in their walls ; in the heart, narrowing of the arterial
or venous orifices or insufficiency or incompetency of the valves. Incompetency
of the valves forms an obstruction to the movement of the blood, by allowing
part of the blood to flow back or regurgitate, thus throwing extra work upon
Thus arise (1.) Hypertrophy of the left ventricle, owing to resistance in the area
of the systemic circulation, especially in the arteries and capillaries not in the
veins. Amongst the causes are, constriction of the orifice or other parts of the
aorta, calcification, atheroma, and want of elasticity of the large arteries and
irregular dilatations in their course (Aneurisms) ; insufficiency of the aortic
valves, in which case the same pressure always obtain within the ventricle and in
the aorta ; and lastly, contraction of the kidneys, so that the excretion of water by
these organs is diminished. Even in mitral insufficiency compensatory hyper-
trophy of the left ventricle must occur, owing to the hypertrophy of the left atrium
in. consequence of the increased blood-pressure in the pulmonary circuit.
80 THE APEX-BEAT.
(2. ) Hypertrophy of the left auricle occurs in stenosis of the left auriculo- ven-
tricular orifice, or in insufficiency of the mitral valve, and it occurs also as a result
of aortic insufficiency, because the auricle has to overcome the continual aortic
pressure within the ventricle.
(3.) Hypertrophy of the right ventricle, occurs (a.) when there is resistance to
the blood-stream through the pulmonary circuit. The resistance may be due to
(a.) obliteration of large vascular areas in consequence of destruction, shrinking or
compression of the lungs, and the disappearance of numerous capillaries in emphy-
sematous lungs. (/3.) Overfilling of the pulmonary circuit with blood in conse-
quence of stenosis of the left auriculo-ventricular orifice or mitral insufficiency
consequent upon hypertrophy of the left auricle resulting from aortic insufficiency.
(&. ) Hypertrophy of the right ventricle will also occur when the valves of the
pulmonary artery are insufficient, thus permitting the blood to flow back into the
ventricle, so that the pressure within the pulmonary artery prevails within the
right ventricle (very rare).
(4.) Hypertrophy of the right auricle occurs in consequence of the last-named
condition, and also from stenosis of the tricuspid orifice, or insufficiency of the
tricuspid valve (rare). If several lesions occur simultaneously, the result is
Artificial Injury to the Valves. O. Rosenbach has made experiments on
the action of the heart when its valves are injured artificially. If the aortic valves
are perforated, with or without simultaneous injury to the mitral or tricuspid
valves, the heart does more work ; thus the physical defect is overcome for a time,
so that the blood-pressure does not fall. The heart seems to have a store of
reserve energy, which is called into play. Soon, however, dilatation takes place,
on account of the regurgitation of the blood into the heart. Hypertrophy then
occurs, but the compensation meanwhile must be obtained through the reserve
energy of the heart.
Impeded Diastole. Among causes which hinder the diastole of the heart are
copious effusions into the pericardium, or pressure of tumours upon the heart. The
systole is greatly interfered with when the heart is united to the pericardium and
to the connective tissue in the mediastinum. As a consequence the connective
tissue, and even the thoracic wall, are drawn in during contraction of the heart,
so that there is a retraction of the region of the apex-beat during systole, and a
protrusion of this part during the diastole.
50. The Apex-Beat The Cardiogram.
Cardiac Impulse. By the term "apex-beat" or cardiac impulse, is
understood under normal circumstances an elevation (perceptible to
touch and sight) in a circumscribed area of the fifth left intercostal
space, caused by the movement of the heart. [The apex-beat is felt in
the fifth left intercostal space, two inches below the nipple, and one
inch to its sternal side.] The impulse is more rarely felt in the fourth
intercostal space, and it is much less distinct when the heart beats
against the fifth rib itself. The position and force of the cardiac
impulse vary with changes in the position of the body.
[Methods. To obtain a curve of the apex-beat or a cardiogram, we may
use one or other of the following cardiographs (Fig. 25). Fig. 25, A, is the
first form used by Marey, and it consists of an oval wooden capsule applied in an
air-tight manner over the apex-beat. The disc, p, capable of being regulated by the
screw, s, presses upon the region of the apex-beat, while t is a tube which may
be connected with a registering tambour (Fig. 28). B is an improved form of
the instrument, consisting essentially of a tambour, while attached to the mem-
brane is a button, p, to be applied over the apex-beat. The movements of the air
within the capsule are communicated by the tube, t, to a registering tambour. Fig.
25, C, is the pansphygmograph of Brondgeest, which consists of a Marey's tam-
bour, in an iron horse-shoe frame, and adjustable by means of a screw, s. Burdon-
Sanderson's cardiograph is shown in D. The button, p, carried by the spring, e,
does not rest upon the caoutchouc membrane, but on an aluminium plate
attached to it. The apparatus is adjusted to the chest by three supports.
Fig. 25, E, shows a modified instrument on the same principle by Grunmach
and v. Knoll. In all these figures the t indicates the exit-tube communicating
with a registering tambour (Fig. 28). D and E may be used for other purposes,
e.g., for the pulse, so that they are polygraphs. See also Fig. 52.]
Various cardiographs A, original form as used by Marey; B, improved form by
Marey; C, Pansphygmograph of Brondgeest; D, Cardiograph of Burdon-
Sanderson ; E, that of Grunmach and v. Knoll.
Fig. 25$, A, shows the cardiogram or the impulse-curve of the heart of
a healthy man ; B, that of a dog, obtained by means of a sphygmo-
graph. In both the following points are to be noticed a, b, corre-
sponds to the time of the pause and the contraction of the auricles. As
the atria contract in the direction of the axis of the heart from
the right and above towards the left and below, the apex of the
heart moves towards the intercostal space. The two or three smaller
Curves taken from the apex-beat A, normal curve from man ; B, from a dog ;
C, very rapid curve from a dog ; D and E, normal curves from a man, regis-
tered on a vibrating glass-plate where each indentation = 0'01613 sees. In
all the curves, a, b, means contraction of the auricles ; 6, c, ventricular
systole ; d, closure of the aortic valves ; e, closure of the pulmonary artery
valves ; e, /, relaxation or diastole of the ventricle.
elevations are perhaps caused by the contractions of the ends of the
veins, the auricular appendices, and the atria themselves.
Some observers ascribe the small elevations occurring before b to the filling of
the ventricle during the diastole, whereby it is pressed against the intercostal
space (Maurer, Griitzner).
The portion, b, c, which communicates the greatest impulse to the
instrument, and also to one's hand when it is placed on the apex-
beat, is caused by the contraction of the ventricle, and during it the first
sound of the heart occurs. Frequently, but erroneously, the cardiac
impulse has been ascribed to this contraction of the ventricle. It
however, is due to all those conditions which cause an elevation in the
region of the apex-beat.
CAUSE OF THE CARDIAC IMPULSE.
The cause of the ventricular impulse, has been much discussed. It
depends upon the following :
(1.) The base of the heart (auriculo-ventricular groove) represents
during diastole a transversely-placed ellipse, while during contraction it
has a more circular figure. Thus, the long diameter of the ellipse is
diminished in the cat from 28 to 2 2 '5 mm. (C. Ludwig) ; the small
diameter is increased ( T \j- to -J-), while the base is brought nearer to
the chest-wall (Arnold, Ludwig) Fig. 26, 1. This alone does not cause
the impulse, but the basis of the heart, being hardened during the
systole and brought nearer to the chest-wall, allows the apex to
execute the movement which causes the impulse.
(2.) During relaxation, the ventricle lies with its apex obliquely
downwards, and with its long axis in an oblique direction so that the
angles formed by the axis of the ventricles with the diameter of the
base are unequal represents a regular cone, with its axis at right angles
to its base. Hence, the apex must be erected from below and behind,
forwards and upwards (Harvey " cor sese erigere "), and when
hardened during systole presses itself into the intercostal space
(Ludwig) Fig." 2 G, II.
I, Schematic horizontal section through the heart and lungs, and the thoracic
walls, to show the change of shape which the base of the heart undergoes
during contraction of the ventricle 1, 2, transverse diameter of the ventricle
during diastole ; c, position of the thoracic wall during diastole ; a, b, trans-
verse diameter of the heart during systole, with e, the position of the anterio r
thoracic wall during systole. II, Side-view of the heart s, apex during
diastole ; p, the same during systole (C. Ludwig).
84 CAUSE OF THE CARDIAC IMPULSE.
(3.) The ventricle undergoes during systole a slight spiral twisting
on its long axis ("lateralem inclinationem" Harvey), so that the apex
is brought from behind more forward, and thus a greater portion of the
left ventricle is turned to the front. This rotation is caused by the
muscular fibres of the ventricles, which proceed from that part of the
fibrous rings between the auricles and ventricles which lies next the
anterior thoracic wall. The fibres pass from above obliquely down-
wards, and to the left, and also run in part upon the posterior surface
of the ventricle. "When they contract in the axis of their direction,
they tend to raise the apex, and also to bring more of the posterior
surface of the heart in relation with the anterior thoracic wall (Harvey,
Kiirschner, Wilckens). This rotation is favoured by the slightly spiral
arrangement of the aorta and pulmonary artery (Kornitzer).
These are the most important causes, but minor causes are as
(4.) The " reaction impulse " is that movement which the ventricles
are said to undergo (like an exploded gun or rocket) at the moment
when the blood is discharged into the aorta and pulmonary artery,
whereby the apex goes in the opposite direction i.e., downwards and
slightly outwards (Alderson 1825, Gutbrod, Skoda, Hiffelsheim).
Landois, however, has shown that the mass of blood is discharged into
the vessels 0*08 of a second after the beginning of the systole, while
the cardiac impulse occurs with the first sound.
(5.) When the blood is discharged into the aorta and pulmonary
artery, these vessels are slightly elongated, owing to the increased blood-
pressure (Senac). As the heart is suspended from above by these
vessels, the apex is pressed slightly downwards and forwards towards
the intercostal space (?)
Guttmann and Jahn observed that the cardiac impulse disappeared after sudden
ligature of the aorta and pulmonary artery, while Chauveau and Rosenstein
maintain that it persists.
As the cardiac impulse is observed in the empty hearts of dead
animals, (4) and (5) are certainly of only second-rate importance. Filehne
and Pentzoldt maintain that the apex during systole does not move to
the left and downwards, as must be the case in (4) and (5), but that it
moves upwards and to the right a result corroborated by v. Ziemssen,
which, however, is disputed by Losch.
It is to be remembered that as the apex is alicays applied to the chest-wall,
separated from it merely by the thin margin of the lung, it only presses
against the intercostal space during systole (Kiwisch).
After the apex of the curve, c, has been reached at the end of the
THE TIME OCCUPIED BY THE CARDIAC MOVEMENTS. 85
systole, the curve falls rapidly, as the ventricle rapidly becomes relaxed.
In the descending part of the curve, at d and e, are two elevations,
which occur simultaneously with the second sound. These are caused by
the sudden closure of the semi-lunar valves, which, occurring suddenly,
is propagated through the axis of the ventricle to its apex, and thus
causes a vibration of the intercostal space; d corresponds to the
closure ' of the aortic valves, and e to the closure of the pulmonary
valves. The closure of the valves in these two vessels is not simul-
taneous, but is separated by an interval of 0*05 to 0'09 sec. The
aortic valves close sooner on account of the greater blood-pressure
there (Landois, 1876, Ott and Haas, Malbranc, Maurer, Griitzner,
Langendorff, v. Ziemssen, and Ter Gregorianz).
Complete diastolic relaxation of the ventricle occurs from e to / in
the curve. It is clear, then, that the cardiac impulse is caused chiefly
by the contraction of the ventricles, while the auricular systole and the
vibration caused by the closure of the semi-lunar valves are also con-
cerned in its production.
51. The Time Occupied by the Cardiac
Methods. The time occupied by the various phases of the movements of the
heart may be determined by studying the apex-beat curve.
(1.) If we know at what rate the plate on which the curve was obtained moved
during the experiment, of course all that is necessary is to measure the distance,
and so calculate the time occupied by any event (see Pulse).
(2.) It is preferable, however, to cause a tuning-fork, whose rate of vibration
is known, to write its vibrations under the curve of the apex-beat, or the
curve may be written upon a plate attached to a vibrating tuning-fork (Fig.
25a, D, E). Such a curve contains fine teeth, caused by the vibrations of the
tuning-fork. D and E are curves obtained from the cardiac impulse in this way
from healthy students. In D the notch eZ, is not indicated. Each complete
vibration of the tuning-fork, reckoned from apex to apex of the teeth =0*01613
sec., so that it is simply necessary to count the number of teeth and multiply to
obtain the time. The values obtained vary within certain limits even in health.
Pause and Contraction of Auricles. The value of a &=pause-r- con-
traction of the auricles is subject to the greatest variation, and depends
chiefly upon the number of heart-beats per minute. The more quickly
the heart beats, the smaller is the pause, and conversely. In some
curves, even when the heart beats slowly, it is scarcely possible to
distinguish the auricular contraction (indicated by a rise) from the
part of the curve corresponding to the pause (indicated by a horizontal
line). In one case (heart-beats 55 per minute) the pause = 0*4 sec,, the
auricular contraction = '17 7 sec. In Fig. 25a, A, the time occupied by
the pause + the auricular contraction (74 beats per minute) = 0'5 sec.
86 TIME OCCUPIED BY THE VENTRICULAR SYSTOLE.
In D the a 5=19 to 20 vibrations = 0' 3 2 sec.; in E= 2 6 vibrations
= 0-42 sec.
Ventricular Systole. The ventricular systole is calculated from the
beginning of the contraction, b to e, when the semi-lunar valves are
closed ; it lasts from the first to the second sound. It also varies
somewhat, but is more constant. When the heart beats rapidly, it is
somewhat less during slow action, greater. In E = 0'32 sec.; in D
= 0'29 sec. ; with 55 beats per minute Landois found it = 0*34, with a
very high rate of beating = '19 9 sec.
When the ventricle beats feebly, it contracts more slowly, as can be shown by
applying the registering apparatus to the heart of an animal just killed. In Fig.
27, from the ventricle of a rabbit just killed, the slow heart-beats, B, are seen to
Curves obtained from the ventricle of a rabbit, and written upon a vibrating plate
attached to a tuning-fork (vibration = 0'01613 sec.) A, tolerably soon after
death ; B, from the dying ventricle.
In calculating the time occupied by the ventricular systole we must remember
(1.) The time between the two sounds of the heart, i.e., from the beginning of the