LECTURES OJST THE VASCULO-CARDIACS.?BY A. CROMBIE.
October 1, 1874.]
ORIGINAL COMMUNICATIONS. LECTURES ON THE VASCULO-CARDIACS*
By Alexander Cuombie, M.D., Ediv., Officiating Professor of Materia Mediea and Clinical Medicine, Medical College, Calcutta. LECTURE I.?DIGITALIS.
[Preliminary
remarks
having
of the arterial system, the tions of the instruments
ACTION ON THE VESSELS.
been made
on the anatomy and physiology pulse, and the blood-pressure, with explanafor measuring it, the_ manometer and the
tymographion:?] Effect of high hlooi pressure on the sphyg mographic tracing.? It is heightened and rounded with a more gradual descent than in health. The heightening of the tracing may be due partly to increased energy of the heart's action, forcing the blood more suddenly into the'arterial system, and thus raising its state of
tension ; but this would not account for its rounded appearance and the gradual descent. These must depend on some altered condition of the arterial system itself, for they are tracings of phenomena which occur after the closure of the semilunar valves, *??., after the direct effect of the ventricular contraction on the arterial system has ceased. In reality the heart takes small, if any,
Part in
increasing
the blood pressure, for both increase and dimi-
nution of arterial tension coincide with the most various rates of the pi use and force of the cardiac contractions. Only the ascending line of the sphygmographic tracing marks the effect of the ventricular contraction on the distension of the arteries- It indicates the ease with which the ventricle overcomes the forces
opposed elasticity of the vessels and the tension of their contents. The more rapidly it overcomes this' opposition the niore sudden will be the effect produced on the arterial system, and the more perpendicular the ascending line of the sphygmographic drawing. In health the ascending line is nearly perpendicular. In the diagram it is seen to occupy only about half of one of the spaces between the perpendicular lines from its commencement to its summit. This indicates the time spent in overcoming the elasticity of the arterial, system. Under certain circumstances the ventricle has greater difficulty in overcoming this elastie'ty, and the ascent of this line is more gradual, for in correspondence with the increased difficulty which the ventricle experiences Jn emptying itself is the length of time spent in to
it, viz.,
the
it. In "stenosis of the aortic orifice a mechanical is offered to the effort of the ventricle to empty itself on account of the narrowing of its outlet, and here is a tracing t-'ken of the pulse of a patient suffering from this difficulty,
overcoming
difficulty
^ou
see
?f
man
a
how sloping is the ascending line compared with.that in whom
to pass
no
such
difficulty
exists.
Less blood is able
through the constricted orifice in a given time, and therefore the distension of the arterial system is accomplished niore slowly, and consequently the ascending line of the tracing,
which marks this distension, is more sloping than in health. ^?u will also notice that it does not in health, go so high as t e-> the state of arterial distension is never so great. The reason of this is that all the while the ventricle is contracting and emptying itself into the arterial tubes the blood is escaping at the other end of them into the capillaries. The pulse is s?tall but sustained.
In aortic regurgitation how different is the character of the tracing. ln this cnso less difficulty than usual is experienced 3" the ventricle in emptying itself into the aorta. The arterial s3 stem at the time of the ventricular contraction is then
tbpy
?nd I the
emptier
C[/fn" c'a.'m tf
118 treat
to originality in these lectures. The information which scattered in the pages of our more scientific journals ; think that it will noi be unacceptable to the readers of Gazette in a collected form, and that we will none of cases intelligently or less skilfully for this rechauffe of
t
"n
reee?UH ii&Portpn'J
'?ss
pur
c
i
accl"'re(l knowledge of the physiological actions of this remedies.?A. C.
clU5s of
253
of blood than in health, for during the ventricular diastole the aorta has emptied itself back into the ventricle. Consequently the opposition offered to the ventricle is less than in health, for the tension of the contents of the arterial system is less, and ascending line of the tracing is perpendicular. But notice how sharp the summit of the tracing has been made That is the
by the ventricular contraction was only momentary. The next instant came the recoil of the elastic arteries, and they emptied themselves back into because the state of tension caused
the ventricle.
system is in this condition like an elastic tube both ends, and it empties itself in both directions with great rapidity when the distending force has ceased. The pulse " feels lilseb alls of blood shot under the finger." The arterial
open
at
But in health the recoil of the elastic arteries closes the aortic valves with a force that makes them ring again as you can hear with your stethoscope, and then the emptying of the for instead of doing so through the more gradual, wide aortic-orifice and the capillaries at the same time, it can only take place through the narrow opening of the latter, the former orifice being closed by the semilunar valves. The arterial system in health is like a tube with its contained fluid arteries is
issuing from a narrow orifice at one end only. Now the descending line of the tracing marks the rapidity with which the emptying of the arteries takes place through this narrow It must be obvious to you that orifice of the capillaries. if this single narrow orifice is widened the rapidity with which the elasticity of the arteries will enable them to empty themselves will be greater than in health, and the effect on the same as if the aortic orifice had not closed, and the sphygmographic tracing will approach
downward curve will be the been
in character that of aortic summit of the curve will be
regurgitation, that sharp in proportion
is
to
to
the
with which the blood escapes from the arteries into
say,
the
rapidity the capilla-
ries; and at the same time the arterial tubes being thus rapidly emptied, less opposition will be offered to the next ventricular contraction, and the next sphygmographic curve will have a perpendicular ascending line. "We have several means of widening the orifice3 by which the blood can escape from the pressure of the elastic arteries, and by all of them this peculiar sphygmographic tracing is pro-
duced.
Dividing a large artery i3 one, but it is seldom resorted to now; but nitrite of amyl., nauseating drugs, chloral, and alcohol also do it, and they do so by relaxing the natural degree of contraction in the muscular walls of the small arteries, by which the narrow orifice from the elastic arterial system into the capillaries is kept half closed in health. They throw this door wide open, and no sooner are the arteries distended the ventricle than the blood rushes out of them through thi$ widened orifice, and we get the peculiar soft jerking and
by
the
pulse, peculiar pointed sphygmographic tracing, which characterise
the
physiological
action of these substances.
And it must be equally obvious to you that whatever narrows these passages from the elastic arteries into the capillaries will have the contrary effect of increasing the with which
difficulty
the blood can escape from the former into the latter; and this It has exactly the contrary effect to is what digitalis does. nitrite of amyl., the nauseating emetics, &c. It increases the
natural semi-contraction of the muscular walls of the small arteries, and entirely or three-quarters closes the half open The. doors that lead from the arterial into the capillary systems. contraction of the arteries after the injection of digitalin into the circulation may be demonstrated in the mesentery of tha rabbit. The contraction may be so great as to obliterate the lumen of the vessel and arrest the passage of blood through it. The neccssary consequence of this is that the blood under the vis a tcrgo of the elastic arteries passes through these vessels with less ease than usual; the tension of the arterial svstern is maintained for a longer time; and this is evident in the
THE INDIAN MEDICAL GAZETTE.
254
sphygmographic tracing of a pulse under the influence of digitalis. You see how rounded the summit of each curve is, and how gradual the fall of the descending line. These appearances are caused by the slowness with which the distended arteries are able to recover their state of equilibrium before their next distension by the left ventricle emptying itself into them. The blood escaping from them with less ease through the contracted arterioles keeps them longer in a state of distension than in health.
Now, it must again be obvious to you that, if the highly elastic arteries are thus kept in a state of distension by this difficulty offered to the escape of blood from them by the contraction of the arterioles, the pressure exerted by their elastic on their contained blood must at any moment be
walls
greator
than in the natural condition of matters, when the blood
escapes from them readily. And this is the second point which you must keep in your minds with regard to the action of digitalis, that under its influence the blood in the arterial tubes is subjected to increased pressure by their elastic walls. It is the mechanical consequence of the action of the drug on the small arteries and of the physical conditions of the arterial system. This is no peculiarity of digitalis ; anything else which will cause contraction of the arterioles will produce the same effect; pressure with the finger on a large artery will do it; ergot will do it, and so will belladonna in small doses ; for they both cause contraction of the small arteries, and hinder the escape of blood from the arterial system into the capillaries. "What evidence have we that the pressure on the blood is increased? We have both direct and indirect evidence. The direct evidence is that of physiologists; the indirect that of
physicians. The high the aorta
subsequent
blood pressure produced by injecting digitalis into noticed by Blake as long ago as 1839, and experimenters have again and again confirmed his
was
observation. Under its influence the
mean
height
of the mercury
in the tube of the manometer is raised; the more invented kymographion of Fick, which is free from
recently
certain fallacies inherent in the manometer, marks that its C-shaped hollow spring is straightened, and you also obtain the peculiar
sphygmographic tracing I show you. The physician at the bedside notes that the soft pulse becomes firmer, and he hears an accentuated second sound at the base of the heart, by which he estimates the force with which the semilunar valves at the orifice of the aorta
tightened
and thrown
together by
are
the blood under the force of He also notices that the
the recoil of the distended arteries. fluid portion of the urine is increased under its
influence,
and
this he refers to the high blood pressure within the small arteries of the Malpighian tufts, knowing that one of the conditions which favour the passage of fluids through animal membranes is that they should be subjected to pressure. He knows that the same things happen whenever from any cause the blood pressure is raised ; as when there is a general arterial spasm in hysteria and epilepsy, or when the same condition is chronic, with hypertrophied arterioles at one end of the arterial system, and a hypertrophied left ventricle at the other,
antagonising each other as in chronic Bright, disease when urine is passed in large quantity but of low specific gravity. Does digitalis produce contraction of the arteries in virtue of a stimulating action on the vaso-motor centre or on the peripheral terminations of the vaso-motor nerves, or by a direct
action on the muscular fibres of the walls of the small arteries themselves ? There is a difference of opinion on this question. Megevand found that division of one sympathetic in the neck caused a considerable diminution of the high blood pressure caused by
digitalin, and he accordingly argues that arteriole contraction by exciting the central
digitalin produces origin of the vaso-
motor nerves.
[October 1,
1874.
hand, in investigating tension, divided the spinal administering digitalin, and found that
Ackermann,
on
the other
the cause of the increase of arterial cord in the neck before
blood-pressure nevertheless increased. Now the vaso-motor being situated in the medulla oblongata, above the calamus scriptorius, it follows that by division of the spinal
the
centre
cord at the level of the axis the arteries
were
removed from
any influence which could have been exerted by the drug on the vaso-motor centre. He accordingly concludes that this substance
produces
contraction
of thu arteries
independently
of any influence on the vaso-motor centre, and the probabilities are that its action on the blood-vessels is due to excitation of the peripheral terminations of the vaso-motor nerves; or it may be that its action is to stimulate the involuntary muscular flbre3 in their walls directly. Brunton and Meyer corroborate this opinion. They endeavoured to observe whether the injection of digitalin into the circulation caused any alteration in the
calibre of the vessels in the neck as well division of the
of the rabbit's ear after the sympathetic both vagi had been divided. The
as
sympathetic prevented
any influence from
being
transmitted to the vessels of the ear from the vaso-motor centre, while it was necessary to divide the vagi to prevent the
disturbing
influence from the
which would have
explained
hereafter.
conclusions from
ensued had
slowing of the heart's they been left intact as
They were not able experiments, as
these
action will be
to draw any definite the results were not
constant; but the vessels were seen occasionally to empty themselves more rapidly after the injection of digitalin than and this seemed to indicate to them an action on the walls of the vessels themselves rather than on the vaso-motor centre in the medulla.
before,
October 1, 1874.]
ORIGINAL COMMUNICATIONS. LECTURES ON THE VASCULO-CARDIACS*
By Alexander Cuombie, M.D., Ediv., Officiating Professor of Materia Mediea and Clinical Medicine, Medical College, Calcutta. LECTURE I.?DIGITALIS.
[Preliminary
remarks
having
of the arterial system, the tions of the instruments
ACTION ON THE VESSELS.
been made
on the anatomy and physiology pulse, and the blood-pressure, with explanafor measuring it, the_ manometer and the
tymographion:?] Effect of high hlooi pressure on the sphyg mographic tracing.? It is heightened and rounded with a more gradual descent than in health. The heightening of the tracing may be due partly to increased energy of the heart's action, forcing the blood more suddenly into the'arterial system, and thus raising its state of
tension ; but this would not account for its rounded appearance and the gradual descent. These must depend on some altered condition of the arterial system itself, for they are tracings of phenomena which occur after the closure of the semilunar valves, *??., after the direct effect of the ventricular contraction on the arterial system has ceased. In reality the heart takes small, if any,
Part in
increasing
the blood pressure, for both increase and dimi-
nution of arterial tension coincide with the most various rates of the pi use and force of the cardiac contractions. Only the ascending line of the sphygmographic tracing marks the effect of the ventricular contraction on the distension of the arteries- It indicates the ease with which the ventricle overcomes the forces
opposed elasticity of the vessels and the tension of their contents. The more rapidly it overcomes this' opposition the niore sudden will be the effect produced on the arterial system, and the more perpendicular the ascending line of the sphygmographic drawing. In health the ascending line is nearly perpendicular. In the diagram it is seen to occupy only about half of one of the spaces between the perpendicular lines from its commencement to its summit. This indicates the time spent in overcoming the elasticity of the arterial, system. Under certain circumstances the ventricle has greater difficulty in overcoming this elastie'ty, and the ascent of this line is more gradual, for in correspondence with the increased difficulty which the ventricle experiences Jn emptying itself is the length of time spent in to
it, viz.,
the
it. In "stenosis of the aortic orifice a mechanical is offered to the effort of the ventricle to empty itself on account of the narrowing of its outlet, and here is a tracing t-'ken of the pulse of a patient suffering from this difficulty,
overcoming
difficulty
^ou
see
?f
man
a
how sloping is the ascending line compared with.that in whom
to pass
no
such
difficulty
exists.
Less blood is able
through the constricted orifice in a given time, and therefore the distension of the arterial system is accomplished niore slowly, and consequently the ascending line of the tracing,
which marks this distension, is more sloping than in health. ^?u will also notice that it does not in health, go so high as t e-> the state of arterial distension is never so great. The reason of this is that all the while the ventricle is contracting and emptying itself into the arterial tubes the blood is escaping at the other end of them into the capillaries. The pulse is s?tall but sustained.
In aortic regurgitation how different is the character of the tracing. ln this cnso less difficulty than usual is experienced 3" the ventricle in emptying itself into the aorta. The arterial s3 stem at the time of the ventricular contraction is then
tbpy
?nd I the
emptier
C[/fn" c'a.'m tf
118 treat
to originality in these lectures. The information which scattered in the pages of our more scientific journals ; think that it will noi be unacceptable to the readers of Gazette in a collected form, and that we will none of cases intelligently or less skilfully for this rechauffe of
t
"n
reee?UH ii&Portpn'J
'?ss
pur
c
i
accl"'re(l knowledge of the physiological actions of this remedies.?A. C.
clU5s of
253
of blood than in health, for during the ventricular diastole the aorta has emptied itself back into the ventricle. Consequently the opposition offered to the ventricle is less than in health, for the tension of the contents of the arterial system is less, and ascending line of the tracing is perpendicular. But notice how sharp the summit of the tracing has been made That is the
by the ventricular contraction was only momentary. The next instant came the recoil of the elastic arteries, and they emptied themselves back into because the state of tension caused
the ventricle.
system is in this condition like an elastic tube both ends, and it empties itself in both directions with great rapidity when the distending force has ceased. The pulse " feels lilseb alls of blood shot under the finger." The arterial
open
at
But in health the recoil of the elastic arteries closes the aortic valves with a force that makes them ring again as you can hear with your stethoscope, and then the emptying of the for instead of doing so through the more gradual, wide aortic-orifice and the capillaries at the same time, it can only take place through the narrow opening of the latter, the former orifice being closed by the semilunar valves. The arterial system in health is like a tube with its contained fluid arteries is
issuing from a narrow orifice at one end only. Now the descending line of the tracing marks the rapidity with which the emptying of the arteries takes place through this narrow It must be obvious to you that orifice of the capillaries. if this single narrow orifice is widened the rapidity with which the elasticity of the arteries will enable them to empty themselves will be greater than in health, and the effect on the same as if the aortic orifice had not closed, and the sphygmographic tracing will approach
downward curve will be the been
in character that of aortic summit of the curve will be
regurgitation, that sharp in proportion
is
to
to
the
with which the blood escapes from the arteries into
say,
the
rapidity the capilla-
ries; and at the same time the arterial tubes being thus rapidly emptied, less opposition will be offered to the next ventricular contraction, and the next sphygmographic curve will have a perpendicular ascending line. "We have several means of widening the orifice3 by which the blood can escape from the pressure of the elastic arteries, and by all of them this peculiar sphygmographic tracing is pro-
duced.
Dividing a large artery i3 one, but it is seldom resorted to now; but nitrite of amyl., nauseating drugs, chloral, and alcohol also do it, and they do so by relaxing the natural degree of contraction in the muscular walls of the small arteries, by which the narrow orifice from the elastic arterial system into the capillaries is kept half closed in health. They throw this door wide open, and no sooner are the arteries distended the ventricle than the blood rushes out of them through thi$ widened orifice, and we get the peculiar soft jerking and
by
the
pulse, peculiar pointed sphygmographic tracing, which characterise
the
physiological
action of these substances.
And it must be equally obvious to you that whatever narrows these passages from the elastic arteries into the capillaries will have the contrary effect of increasing the with which
difficulty
the blood can escape from the former into the latter; and this It has exactly the contrary effect to is what digitalis does. nitrite of amyl., the nauseating emetics, &c. It increases the
natural semi-contraction of the muscular walls of the small arteries, and entirely or three-quarters closes the half open The. doors that lead from the arterial into the capillary systems. contraction of the arteries after the injection of digitalin into the circulation may be demonstrated in the mesentery of tha rabbit. The contraction may be so great as to obliterate the lumen of the vessel and arrest the passage of blood through it. The neccssary consequence of this is that the blood under the vis a tcrgo of the elastic arteries passes through these vessels with less ease than usual; the tension of the arterial svstern is maintained for a longer time; and this is evident in the
THE INDIAN MEDICAL GAZETTE.
254
sphygmographic tracing of a pulse under the influence of digitalis. You see how rounded the summit of each curve is, and how gradual the fall of the descending line. These appearances are caused by the slowness with which the distended arteries are able to recover their state of equilibrium before their next distension by the left ventricle emptying itself into them. The blood escaping from them with less ease through the contracted arterioles keeps them longer in a state of distension than in health.
Now, it must again be obvious to you that, if the highly elastic arteries are thus kept in a state of distension by this difficulty offered to the escape of blood from them by the contraction of the arterioles, the pressure exerted by their elastic on their contained blood must at any moment be
walls
greator
than in the natural condition of matters, when the blood
escapes from them readily. And this is the second point which you must keep in your minds with regard to the action of digitalis, that under its influence the blood in the arterial tubes is subjected to increased pressure by their elastic walls. It is the mechanical consequence of the action of the drug on the small arteries and of the physical conditions of the arterial system. This is no peculiarity of digitalis ; anything else which will cause contraction of the arterioles will produce the same effect; pressure with the finger on a large artery will do it; ergot will do it, and so will belladonna in small doses ; for they both cause contraction of the small arteries, and hinder the escape of blood from the arterial system into the capillaries. "What evidence have we that the pressure on the blood is increased? We have both direct and indirect evidence. The direct evidence is that of physiologists; the indirect that of
physicians. The high the aorta
subsequent
blood pressure produced by injecting digitalis into noticed by Blake as long ago as 1839, and experimenters have again and again confirmed his
was
observation. Under its influence the
mean
height
of the mercury
in the tube of the manometer is raised; the more invented kymographion of Fick, which is free from
recently
certain fallacies inherent in the manometer, marks that its C-shaped hollow spring is straightened, and you also obtain the peculiar
sphygmographic tracing I show you. The physician at the bedside notes that the soft pulse becomes firmer, and he hears an accentuated second sound at the base of the heart, by which he estimates the force with which the semilunar valves at the orifice of the aorta
tightened
and thrown
together by
are
the blood under the force of He also notices that the
the recoil of the distended arteries. fluid portion of the urine is increased under its
influence,
and
this he refers to the high blood pressure within the small arteries of the Malpighian tufts, knowing that one of the conditions which favour the passage of fluids through animal membranes is that they should be subjected to pressure. He knows that the same things happen whenever from any cause the blood pressure is raised ; as when there is a general arterial spasm in hysteria and epilepsy, or when the same condition is chronic, with hypertrophied arterioles at one end of the arterial system, and a hypertrophied left ventricle at the other,
antagonising each other as in chronic Bright, disease when urine is passed in large quantity but of low specific gravity. Does digitalis produce contraction of the arteries in virtue of a stimulating action on the vaso-motor centre or on the peripheral terminations of the vaso-motor nerves, or by a direct
action on the muscular fibres of the walls of the small arteries themselves ? There is a difference of opinion on this question. Megevand found that division of one sympathetic in the neck caused a considerable diminution of the high blood pressure caused by
digitalin, and he accordingly argues that arteriole contraction by exciting the central
digitalin produces origin of the vaso-
motor nerves.
[October 1,
1874.
hand, in investigating tension, divided the spinal administering digitalin, and found that
Ackermann,
on
the other
the cause of the increase of arterial cord in the neck before
blood-pressure nevertheless increased. Now the vaso-motor being situated in the medulla oblongata, above the calamus scriptorius, it follows that by division of the spinal
the
centre
cord at the level of the axis the arteries
were
removed from
any influence which could have been exerted by the drug on the vaso-motor centre. He accordingly concludes that this substance
produces
contraction
of thu arteries
independently
of any influence on the vaso-motor centre, and the probabilities are that its action on the blood-vessels is due to excitation of the peripheral terminations of the vaso-motor nerves; or it may be that its action is to stimulate the involuntary muscular flbre3 in their walls directly. Brunton and Meyer corroborate this opinion. They endeavoured to observe whether the injection of digitalin into the circulation caused any alteration in the
calibre of the vessels in the neck as well division of the
of the rabbit's ear after the sympathetic both vagi had been divided. The
as
sympathetic prevented
any influence from
being
transmitted to the vessels of the ear from the vaso-motor centre, while it was necessary to divide the vagi to prevent the
disturbing
influence from the
which would have
explained
hereafter.
conclusions from
ensued had
slowing of the heart's they been left intact as
They were not able experiments, as
these
action will be
to draw any definite the results were not
constant; but the vessels were seen occasionally to empty themselves more rapidly after the injection of digitalin than and this seemed to indicate to them an action on the walls of the vessels themselves rather than on the vaso-motor centre in the medulla.
before,
