Book - Congenital Cardiac Disease 7: Difference between revisions

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Defects at the Base. - The cases of congenital cardiac disease here  
==Defects at the Base==
studied have been drawn only from reliable sources, and all have postmortem reports attached, which should make them a fair index of relative frequency. It is therefore of interest to note that among them,  
 
while defects elsewhere in the septum are exceedingly rare, "pure"  
The cases of congenital cardiac disease here studied have been drawn only from reliable sources, and all have postmortem reports attached, which should make them a fair index of relative frequency. It is therefore of interest to note that among them, while defects elsewhere in the septum are exceedingly rare, "pure"  
defects at the base are commoner than is usually supposed, and, in  
defects at the base are commoner than is usually supposed, and, in combination with other defects they rank as the most frequent cardiac anomaly.  
combination with other defects they rank as the most frequent cardiac  
 
anomaly.  


Among the 631 cases, a defect at the base occurred 177 times, elsewhere than at the base, 12 times, making 189 cases, or 30 per cent. Of  
Among the 631 cases, a defect at the base occurred 177 times, elsewhere than at the base, 12 times, making 189 cases, or 30 per cent. Of  
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leaving 22 "pure" defects at the base unassociated with rechtslage or  
leaving 22 "pure" defects at the base unassociated with rechtslage or  
other anomaly except (in 5 cases) bicuspid or defective aortic or pulmonary valves  
other anomaly except (in 5 cases) bicuspid or defective aortic or pulmonary valves  


Of the 143 defects at the base complicating other anomalies, 75 were  
Of the 143 defects at the base complicating other anomalies, 75 were  
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in two.  
in two.  


Pathogenesis. - The combination of a defect of the interventricular  
===Pathogenesis===
septum vvith pulmonary stenosis and rechtslage of the aorta constitutes  
 
one of the commonest forms of congenital cardiac disease. So frequent  
The combination of a defect of the interventricular septum vvith pulmonary stenosis and rechtslage of the aorta constitutes one of the commonest forms of congenital cardiac disease. So frequent is the combination that a causal connection between the three conditions has been sought, and rival theories as to which is the primary lesion have been suggested.  
is the combination that a causal connection between the three conditions  
 
has been sought, and rival theories as to which is the primary lesion have  
been suggested.  


Much light was thrown upon this subject by Rokitansky, who concluded that non-inflammatory pulmonary stenosis, displacement to  
Much light was thrown upon this subject by Rokitansky, who concluded that non-inflammatory pulmonary stenosis, displacement to  
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[[File:Abbott 28.jpg|600px]]


Fig. 28 Defect of the interventricular septum at undefended space. Heart of infant. No other anomaly. (From a specimen in the McGill Pathological Museum.)


Fig. 28


 
Later advances in embryological knowledge show that the aortic septum is prolonged downward to assist in closing the interventricular septum at the undefended space, instead of the interventricular septum growing upward to form part of the aortic wall, as Rokitansky supposed. Moreover, independent defects of the interventricular septum in this situation, unassociated with any alterations in the relations of the great arterial trunks, and evidently not of inflammatory origin, may and do occur. This is so in the specimen seen in Fig. 28, and in cases reported by Orth,^ Arnold, Preisz,^ and Hart.^  
 
Such conditions cannot be explained on Rokitansky's theory as due to deviation of the septum, or, a deficient expansion of the infundibuhim, but  
 
 
Later advances in embryological knowledge show that the aortic  
septum is prolonged downward to assist in closing the interventricular  
septum at the undefended space, instead of the interventricular septum  
growing upward to form part of the aortic wall, as Rokitansky supposed.  
Moreover, independent defects of the interventricular septum in this  
situation, unassociated with any alterations in the relations of the great  
arterial trunks, and evidently not of inflammatory origin, may and do  
occur. This is so in the specimen seen in Fig. 28, and in cases reported  
by Orth,^ Arnold, Preisz,^ and Hart.^  
Such conditions cannot be explained  
on Rokitansky's theory as due to deviation of the septum, or, a deficient  
expansion of the infundibuhim, but  
are due, as Keith himself points  
are due, as Keith himself points  
out, to a primary arrest of growth  
out, to a primary arrest of growth  
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of the conus of the right ventricle  
of the conus of the right ventricle  
through the septal opening, to the  
through the septal opening, to the  
anterior segment of the mitral valve.  
anterior segment of the mitral valve.


Pathology. - The commonest situation for the defect is directly beneath
===Pathology===
the aortic cusps and just anterior to
the undefended space (Rokitansky's
posterior part of the anterior septum) (Fig. 28). Here it lies with the
fleshy muscular septum before it and
the thin pars membranacea behind,


and opens in the right heart beneath the septal cusp of the tricuspid,  
The commonest situation for the defect is directly beneath the aortic cusps and just anterior to the undefended space (Rokitansky's posterior part of the anterior septum) (Fig. 28). Here it lies with the fleshy muscular septum before it and the thin pars membranacea behind, and opens in the right heart beneath the septal cusp of the tricuspid, sometimes perforating this or bulging the (adherent) tricuspid leaflet before it, or opening into the right auricle directly above the base of the tricuspid, thus establishing a communication between this cavity and the two ventricles. IMore rarely the defect is placed farther forward in the septum in its anterior fleshy part, just behind the front wall of the heart, and is separated behind from the undefended space by a muscular column, opening into the conus of the right ventricle below the pulmonary valves. (Rokitansky's anterior part of the anterior septum). Examples are the cases by Coupland^ and Rolleston.^ Keith points out that in these cases, the defect is evidently in the musculature of the interbulbar septum, i. e., it is in that part of the interventricular septum which in the embryo formed the proximal part of the bulbus cordis before its division into the conus of the pulmonary artery and the vestibule of the aorta.  
sometimes perforating this or bulging the (adherent) tricuspid leaflet  
before it, or opening into the right auricle directly above the base of the  
tricuspid, thus establishing a communication between this cavity and  
the two ventricles. IMore rarely the defect is placed farther forward  
in the septum in its anterior fleshy part, just behind the front wall of the  
heart, and is separated behind from the undefended space by a muscular  
column, opening into the conus of the right ventricle below the pulmonary valves. (Rokitansky's anterior part of the anterior septum).  
Examples are the cases by Coupland^ and Rolleston.^ Keith points  
out that in these cases, the defect is evidently in the musculature of the  
interbulbar septum, i. e., it is in that part of the interventricular septum which in the embryo formed the proximal part of the bulbus cordis  
before its division into the conus of the pulmonary artery and the vestibule of the aorta.  




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The defect varies in form and size from a pinhead perforation with  
The defect varies in form and size from a pinhead perforation with tendinous edges, a round or oval hole admitting a goose-quill, knitting needle, index finger, etc., to a large triangular, semilunar, or crescentic space with thick-walled lower muscular border. Aneurismal pouching of the pars membranacea into the right ventricle may occur, with multiple sacculations perforated at their apices at one or more points (vide infra).  
tendinous edges, a round or oval hole admitting a goose-quill, knitting  
needle, index finger, etc., to a large triangular, semilunar, or crescentic  
space with thick-walled lower muscular border. Aneurismal pouching  
of the pars membranacea into the right ventricle may occur, with multiple  
sacculations perforated at their apices at one or more points (vide infra) .  


Quite frequently the margins of the defect with the adjacent valves
are the seat of an acute inflammatory process which apparently originates
at this point, because, as the seat of greatest strain,' it affords a site of
lowered resistance. Such a case is reported by Gordon.^ In a boy
aged five years who died of malignant endocarditis, a marked precordial
thrill, and loud, harsh systolic murmur over the whole chest, with maximum intensity at the third and fourth left cartilages, indicated the septal
defect. The autopsy showed a congenital opening, admitting a lead
pencil, between the ventricles. The pulmonary valves and adjacent
M^all of the right ventricle were the seat of a number of large grayishgreen vegetations which extended below the level of the interventricular
opening.


Moschcowitz^ related a very similar finding in a woman of twenty-nine
Quite frequently the margins of the defect with the adjacent valves are the seat of an acute inflammatory process which apparently originates at this point, because, as the seat of greatest strain,' it affords a site of lowered resistance. Such a case is reported by Gordon.^ In a boy aged five years who died of malignant endocarditis, a marked precordial thrill, and loud, harsh systolic murmur over the whole chest, with maximum intensity at the third and fourth left cartilages, indicated the septal defect. The autopsy showed a congenital opening, admitting a lead pencil, between the ventricles. The pulmonary valves and adjacent wall of the right ventricle were the seat of a number of large grayishgreen vegetations which extended below the level of the interventricular opening.  
years, who had had cardiac symptoms, palpitation, dyspnoea and occasional oedema of the legs since her fifteenth year, with exacerbation during the last four months, and symptoms of acute infection with chills and
septic fever for one week. The blood cultures on one occasion showed  
Streptococcus viridans. At the autopsy both ventricles were hypertrophied,  
and the right also dilated, and there was a defect in the membranous
septum admitting a lead-pencil. The pulmonary valves were replaced
by large gray pedunculated vegetations, which extended up the wall of
the pulmonary artery to its bifurcation, and had led to multiple emboli
in either lung. The prolonged history of cardiac symptoms without
adequate cause suggested a congenital lesion upon which the malignant
endocarditis had been engrafted.  


Dr. W. Thalhimer has sent me photographs of a heart from a cyanotic
boy of nine years, with a huge septal defect and pulmonary stenosis in
which a vegetative process had developed along the line of closure of the
mitral and tricuspid valves. As there was no clinical history of an infective process, no Aschoff bodies in the myocardium, and no evidences of
bacteria in the vegetations on microscopic examination, he is inclined
to explain the vegetations on the ground of mechanical strain by the
unnatural whirls in the blood stream, which have caused microscopic
injuries of the valves and have thus given rise to an aseptic thrombosis.
From a statistical study of the literature one is led to conclude that, at
least in a large proportion of cases, the infective nature of the inflammatory process, so common in the neighborhood of cardiac defects,
has been demonstrated.


----
Moschcowitz^ related a very similar finding in a woman of twenty-nine years, who had had cardiac symptoms, palpitation, dyspnoea and occasional oedema of the legs since her fifteenth year, with exacerbation during the last four months, and symptoms of acute infection with chills and septic fever for one week. The blood cultures on one occasion showed Streptococcus viridans. At the autopsy both ventricles were hypertrophied, and the right also dilated, and there was a defect in the membranous septum admitting a lead-pencil. The pulmonary valves were replaced by large gray pedunculated vegetations, which extended up the wall of the pulmonary artery to its bifurcation, and had led to multiple emboli in either lung. The prolonged history of cardiac symptoms without adequate cause suggested a congenital lesion upon which the malignant endocarditis had been engrafted.  
 
1 Brit. Med. Journ., 1897, ii, 1174. ^ pj-^c. New York Path. Soc, 1914, xiv, 18.  




 
Dr. W. Thalhimer has sent me photographs of a heart from a cyanotic boy of nine years, with a huge septal defect and pulmonary stenosis in which a vegetative process had developed along the line of closure of the mitral and tricuspid valves. As there was no clinical history of an infective process, no Aschoff bodies in the myocardium, and no evidences of bacteria in the vegetations on microscopic examination, he is inclined to explain the vegetations on the ground of mechanical strain by the unnatural whirls in the blood stream, which have caused microscopic injuries of the valves and have thus given rise to an aseptic thrombosis. From a statistical study of the literature one is led to conclude that, at least in a large proportion of cases, the infective nature of the inflammatory process, so common in the neighborhood of cardiac defects, has been demonstrated.  
In a case reported by Hebb^ of a girl, aged eighteen years, whose heart
showed a funnel-shaped defect at the base of the septum admitting a
goose-quill, there were large vegetations bn the aortic, mitral, and pulmonary valves, and a 'patch of vegetations ivas also situated on the wall of the
right ventricle opposite the defect. This observation, which is repeated
in several other cases, as well as the frequent localization of the vegetations in the right ventricle affords an interesting proof of the fact that
under normal conditions the current of blood flows from the left ventricle
to the right through the defect. It is natural to suppose that this would
be so, for the pressure in the systemic circulation is normally higher
than it is in the pulmonary. Further anatomical confirmation of this
direction of the stream is afforded by the oblique direction and funnelshape, with its larger end toward the left ventricle which the opening
often assumes, and also by the not infrequent occurrence of patches of
fibrosis on the opposite wall of the right ventricle.
 
Septal defects may exist without producing any change in the heart
chambers, but they lead, still more frequently than do defects of the
interauricular septum, to hypertrophy and dilatation of both ventricles.
Where the defect is combined with rechtslage of the aorta, marked hypertrophy of the right ventricle is a constant feature. The pulmonary
artery may be markedly dilated, as in 9 cases of the 34 "primary" defects
at the base.
 
The distribution of the auriculoventricular junctional bundle in
septal defects is of much interest, and has been investigated by Keith,
Monckeberg, Morison,^ and others. As is well known this bundle
emerges from the auriculoventricular node close to the interauricular
septum behind the medial cusp of the tricuspid valve, and divides into
two branches, the left of which pierces the interventricular septum just
in front of the pars membranacea, and passes downward superficially
beneath the endocardium of the septum to be distributed to the papillary
muscles and columnee carnese of this chamber, while the right branch
runs, more deeply imbedded in the musculature of the right side of the
septum, to the apex of the right ventricle. In most of the cases of septal
defect examined there was surprisingly little change in this normal
arrangement, the fibres streaming over the free border of the septum
that formed the base of the defect toward the apices of their respective
ventricles. In Morison's case the left branch was abortive. Keith
described an abnormal band of "subaortic musculature," which may
develop in the pars membranacea and overlie the bundle as it courses
down the surface of the septum in the left ventricle, and in one of Monckeberg's cases of septal defect the bundle lay deeply in the musculature
of the left septum instead of sub-endocardially as normally occurs.
Recent investigations by Flack and Mall have shown that the interventricular septum is formed, not by a process growing upward from
below, as Rokitansky supposed, but by a hollowing out of the spongy
musculature of the embryonic ventricle to form the right and left
chambers; the tip of the inferior septum, therefore, represents the wall of the lumen of the original cardiac tube, and this may account for the
persistence of the bundle at this point in septal defects.


----
----


1 Trans. Path. Soc. London, 1897, xlviii, 41.  
1 Brit. Med. Journ., 1897, ii, 1174. ^ pj-^c. New York Path. Soc, 1914, xiv, 18.  


2 Jour. Anat. and Physiol., 1913, xlvii, 459.




In a case reported by Hebb<ref>Trans. Path. Soc. London, 1897, xlviii, 41.</ref> of a girl, aged eighteen years, whose heart showed a funnel-shaped defect at the base of the septum admitting a goose-quill, there were large vegetations bn the aortic, mitral, and pulmonary valves, and a 'patch of vegetations ivas also situated on the wall of the right ventricle opposite the defect. This observation, which is repeated in several other cases, as well as the frequent localization of the vegetations in the right ventricle affords an interesting proof of the fact that under normal conditions the current of blood flows from the left ventricle to the right through the defect. It is natural to suppose that this would be so, for the pressure in the systemic circulation is normally higher than it is in the pulmonary. Further anatomical confirmation of this direction of the stream is afforded by the oblique direction and funnelshape, with its larger end toward the left ventricle which the opening often assumes, and also by the not infrequent occurrence of patches of fibrosis on the opposite wall of the right ventricle.




Symptoms and Physical Signs of Septal Defects. — These may be absent
Septal defects may exist without producing any change in the heart chambers, but they lead, still more frequently than do defects of the interauricular septum, to hypertrophy and dilatation of both ventricles. Where the defect is combined with rechtslage of the aorta, marked hypertrophy of the right ventricle is a constant feature. The pulmonary artery may be markedly dilated, as in 9 cases of the 34 "primary" defects at the base.  
and the defect discovered at autopsy. When cyanosis is present it may
be slight or transient, appearing only on exertion, or terminal at the end
of a long life, or, more rarely, and usually in those cases associated with  
rechtslage of the aorta, it may be well marked. Among the 34 "primary"  
defects at the base there was an entire absence of cyanosis in 17; it was
slight in 5, moderate in 2, marked in 3, and terminal in 4 cases.  


Physical signs may also be absent, as in two otherwise normal hearts
with defects admitting a goose-quill, in the McGill Museum. On the
other hand, physical signs atypical of acquired valvular disease are
often present, even in the absence of symptoms, and are frequently
sufficiently characteristic to permit of a diagnosis being made. In
pronounced cases there may be visible pulsation and precordial bulging,
and a thrill, usually systolic in time and diffuse over the precordium,
or most marked over the middle of the cardia, is common and is more
frequent than in auricular septal defects. A thrill was present in no
less than 11 of the 34 cases of primary defects at the base; in 10 being
systolic and in 1 a "continuous vibration." In 7 it was diffused over
the whole cardia; in 3 it was most marked over its upper half; in 2 others
it was localized at the apex.


A harsh, systolic murmur localized in the third or fourth left space
The distribution of the auriculoventricular junctional bundle in septal defects is of much interest, and has been investigated by Keith, Monckeberg, Morison,<ref> Jour. Anat. and Physiol., 1913, xlvii, 459.</ref> and others. As is well known this bundle emerges from the auriculoventricular node close to the interauricular septum behind the medial cusp of the tricuspid valve, and divides into two branches, the left of which pierces the interventricular septum just in front of the pars membranacea, and passes downward superficially beneath the endocardium of the septum to be distributed to the papillary muscles and columnee carnese of this chamber, while the right branch runs, more deeply imbedded in the musculature of the right side of the septum, to the apex of the right ventricle. In most of the cases of septal defect examined there was surprisingly little change in this normal arrangement, the fibres streaming over the free border of the septum that formed the base of the defect toward the apices of their respective ventricles. In Morison's case the left branch was abortive. Keith described an abnormal band of "subaortic musculature," which may develop in the pars membranacea and overlie the bundle as it courses down the surface of the septum in the left ventricle, and in one of Monckeberg's cases of septal defect the bundle lay deeply in the musculature of the left septum instead of sub-endocardially as normally occurs. Recent investigations by Flack and Mall have shown that the interventricular septum is formed, not by a process growing upward from below, as Rokitansky supposed, but by a hollowing out of the spongy musculature of the embryonic ventricle to form the right and left chambers; the tip of the inferior septum, therefore, represents the wall of the lumen of the original cardiac tube, and this may account for the persistence of the bundle at this point in septal defects.
is the most frequent evidence of the defect. Sometimes a very small
hole may be accompanied by a very loud murmur. Roger described  
as characteristic a " single long, constant murmur beginning with systole
and continuing through both heart sounds, localized in the upper third
of the precordial region." Reiss mentions as typical a loud systolic
murmur in the middle of the precordium, localized over the inner part
of the third left space and the fourth rib.  


A murmur apparently due to the defect was present in 26 of the 34
===Symptoms and Physical Signs of Septal Defects===
cases. In those in which its character was specified it was loud in 18,
rough in 3, whistling, grating, harsh, sawing, each in 1, rasping in 3; in 3
instances it was blowing. It was systolic in rhythm in all 26 cases, and
in 3 of these a diastolic murmur was present as well. The point of
maximum intensity was 12 times in the upper third of the precordium near
the left sternal border; of these, in 4 it was stated to be at the third left
space, in 2 others also at the fourth left space, in 2 at the third costal
cartilage (in 1 of which it was heard with equal intensity at the apex),
in 2 at the pulmonary cartilage and second left space, and in 1 " over the
middle of the sternum opposite the third left interspace." Besides these,
in 2 other cases it was "along the left sternal border," "just to the left
of the xiphoid cartilage," and "at the aortic cartilage;" in 2 (in 1 of  
which it was associated with rechtslage) it was "loudest at the apex,"
and in 4 it was diffuse over the precordium.


The murmur is usually transmitted downward along the left sternal
These may be absent and the defect discovered at autopsy. When cyanosis is present it may be slight or transient, appearing only on exertion, or terminal at the end of a long life, or, more rarely, and usually in those cases associated with rechtslage of the aorta, it may be well marked. Among the 34 "primary"
border, and is frequently heard behind in the left infrascapular region.
defects at the base there was an entire absence of cyanosis in 17; it was slight in 5, moderate in 2, marked in 3, and terminal in 4 cases.  
It may be diffused over the whole precordium, but is usually not heard
in the axilla nor below the clavicle. In 6 cases in this series it was so loud as to be heard over the whole chest, and in 2 cases it could be
traced into the vessels of the neck.  


Eisenmenger^ claimed that a systolic murmur produced by the defect
may be transmitted along the aorta, and thus be heard in the vessels
of the neck, when pulmonary hjq^oplasia is also present, in which
case the blood is diverted by the obstruction from its usual course into
this vessel, and so passes from right to left into the aorta. In his own
case, diagnosed by Schrotter before death, there was a defect admitting
the thumb in the posterior part of the anterior septum, with rechtslage
of the aorta and a dilated pulmonary artery. The patient, a man aged
thirty-two years, had had cyanosis and dyspnoea from birth. There
was visible precordial pulsation and bulging, and a systolic murmur over
the middle of the heart transmitted everjn^v'here over its surface, but
chiefly to the right and inferiorly, not heard above its base, along the
course of the aorta nor in the pulmonary artery, the latter vessel being
too far below the surface to transmit the sound.


Aneurisms of the Undefended Space. - Cases have been recorded
Physical signs may also be absent, as in two otherwise normal hearts with defects admitting a goose-quill, in the McGill Museum. On the other hand, physical signs atypical of acquired valvular disease are often present, even in the absence of symptoms, and are frequently sufficiently characteristic to permit of a diagnosis being made. In pronounced cases there may be visible pulsation and precordial bulging, and a thrill, usually systolic in time and diffuse over the precordium, or most marked over the middle of the cardia, is common and is more frequent than in auricular septal defects. A thrill was present in no less than 11 of the 34 cases of primary defects at the base; in 10 being systolic and in 1 a "continuous vibration." In 7 it was diffused over the whole cardia; in 3 it was most marked over its upper half; in 2 others it was localized at the apex.  
by Rokitansky, Zahn,- Hart,^ IMacCallum,* and others, in which, in the  
absence of any evidence of endocarditis, sacculations, single or multilocular, of the membranous portion of the septum project into the right
auricle above the medial cusp of the tricuspid, and in some cases extend
also into the musculature of the interventricular septum. Malignant
endocarditis of the bulging area is not infrequent and rupture into the
right auricle may occur. On this ground it has been argued^ that these
aneurisms are not of congenital origin, but are due to the action of the
inflammatory process upon this delicate part of the septum. As was
pointed out by Rokitansky, however, the reverse is probably true, the  
aneurism supplying a nidus of lowered resistance upon which an infective
process has been secondarily engrafted. This point has been made the  
subject of an interesting communication by ]\Iall,^ who pronounces
definitely upon the congenital and non-inflammatory origin of these
aneurisms, and shows the cause to be a malposition of the inferior septum
(inferior septum proper) so that "the membranous septum develops
improperly and becomes placed in a horizontal position, and is thus
weakened in every way, and predisposed to the formation of aneurisms."  
In his own case the membranous septum was cribriform, and the hole
communicated with numerous sacs in the medial segment of the tricuspid,
and also bulged into the right atrium.  


Such aneurisms may give rise to marked and characteristic physical
signs. This was true of two remarkable cases, one a heart which is
in the McGill Museum, the other reported by Tate,'' in which a trumpetshaped tube, which formed the apex of a saccular pouching of the pars
membranacea, projected behind and perforated the medial cusp of the
tricuspid valve ; in the McGill specimen there was malignant endocarditis
of the immediately adjacent tricuspid segment.


----
A harsh, systolic murmur localized in the third or fourth left space is the most frequent evidence of the defect. Sometimes a very small hole may be accompanied by a very loud murmur. Roger described as characteristic a " single long, constant murmur beginning with systole and continuing through both heart sounds, localized in the upper third of the precordial region." Reiss mentions as typical a loud systolic murmur in the middle of the precordium, localized over the inner part of the third left space and the fourth rib.  
1 Zeitschr. f. klin. Med., 1897, xxxii, Supp. Heft, 1.  
 
2 Virchows Arch., 1878, Ixxii, 206. » j^j^Z., 1905, clxxxi, 51.
 
* Johns Hopkins Hosp. Bull, 1900, xi, 69. 6 B^hl, Zeits.f. Biol, 1880, xvi.
 
6 Anat. Record, June, 1912, p. 2921.  


7 Trans. Path. Soc. London, 1892, xliii, 36. VOL. IV — 24


A murmur apparently due to the defect was present in 26 of the 34 cases. In those in which its character was specified it was loud in 18, rough in 3, whistling, grating, harsh, sawing, each in 1, rasping in 3; in 3 instances it was blowing. It was systolic in rhythm in all 26 cases, and in 3 of these a diastolic murmur was present as well. The point of maximum intensity was 12 times in the upper third of the precordium near the left sternal border; of these, in 4 it was stated to be at the third left space, in 2 others also at the fourth left space, in 2 at the third costal cartilage (in 1 of which it was heard with equal intensity at the apex),
in 2 at the pulmonary cartilage and second left space, and in 1 " over the middle of the sternum opposite the third left interspace." Besides these, in 2 other cases it was "along the left sternal border," "just to the left of the xiphoid cartilage," and "at the aortic cartilage;" in 2 (in 1 of which it was associated with rechtslage) it was "loudest at the apex," and in 4 it was diffuse over the precordium.




The relative frequency of aneurisms of the right aortic sinus of Valsalva
The murmur is usually transmitted downward along the left sternal border, and is frequently heard behind in the left infrascapular region. It may be diffused over the whole precordium, but is usually not heard in the axilla nor below the clavicle. In 6 cases in this series it was so loud as to be heard over the whole chest, and in 2 cases it could be traced into the vessels of the neck.  
and the probable dependence of these upon the juxtaposition of the pars
membranacea of the right aortic cusp, has been discussed by Hart.^
The insertion of the medial cusp of the tricuspid just behind this point
may further weaken this region by making it a seat of traction. It is
not necessary to presuppose a congenital defect, although this may occur.
In a case reported by Hale White^ an oval defect admitting a No. 10
catheter lay just below the right half of the anterior aortic cusp: its
edges were thickened, but the septum around it for three-quarters of an
inch was thin and translucent, and the sinus of Valsalva above it was
expanded into an aneurismal pouch, which protruded and burst into the  
right ventricle. The author thought that the whole septum between the
lower part of the aorta and the base of the ventricles was abnormally
thin.  


Defects in the Septum Elsewhere than at the Base. - These are usually
multiple, and irregular or slit-like in form. They are of the greatest
rarity. This is especially true of those low down in the septum.


==Complete Absence or Rudimentary Development of the Cardiac Septa==
Eisenmenger^ claimed that a systolic murmur produced by the defect may be transmitted along the aorta, and thus be heard in the vessels of the neck, when pulmonary hypoplasia is also present, in which case the blood is diverted by the obstruction from its usual course into this vessel, and so passes from right to left into the aorta. In his own case, diagnosed by Schrotter before death, there was a defect admitting the thumb in the posterior part of the anterior septum, with rechtslage of the aorta and a dilated pulmonary artery. The patient, a man aged thirty-two years, had had cyanosis and dyspnoea from birth. There
was visible precordial pulsation and bulging, and a systolic murmur over the middle of the heart transmitted everjn^v'here over its surface, but chiefly to the right and inferiorly, not heard above its base, along the course of the aorta nor in the pulmonary artery, the latter vessel being too far below the surface to transmit the sound.


A rudimentary development of the cardiac septa, leading to a diminution in the number of the heart's cavities, should not be treated entirely
==Aneurisms of the Undefended Space==
apart from localized septal defects, being simply a more extreme degree
of the same lesion. Yet the cases may be conveniently grouped together
as indicating arrest at a very early stage of embryonic life (fourth week),
frequently associated with anomalies elsewhere, and as forming an altogether different and more serious picture.


Cor Biloculare. - Early cases were recorded by Wilson in 1798, Farre
Cases have been recorded by Rokitansky, Zahn,<ref>Zeitschr. f. klin. Med., 1897, xxxii, Supp. Heft, 1.</ref> Hart,<ref>Virchows Arch., 1878, Ixxii, 206. » j^j^Z., 1905, clxxxi, 51. </ref> IMacCallum,<ref> Johns Hopkins Hosp. Bull, 1900, xi, 69. 6 B^hl, Zeits.f. Biol, 1880, xvi. </ref> and others, in which, in the  
in 1814, Ramsbotham in 1846, and Forster in 1847, and there are six in
absence of any evidence of endocarditis, sacculations, single or multilocular, of the membranous portion of the septum project into the right auricle above the medial cusp of the tricuspid, and in some cases extend also into the musculature of the interventricular septum. Malignant endocarditis of the bulging area is not infrequent and rupture into the right auricle may occur. On this ground it has been argued^ that these aneurisms are not of congenital origin, but are due to the action of the inflammatory process upon this delicate part of the septum. As was pointed out by Rokitansky, however, the reverse is probably true, the aneurism supplying a nidus of lowered resistance upon which an infective process has been secondarily engrafted. This point has been made the subject of an interesting communication by Mall,<ref>Anat. Record, June, 1912, p. 2921. </ref> who pronounces definitely upon the congenital and non-inflammatory origin of these aneurisms, and shows the cause to be a malposition of the inferior septum (inferior septum proper) so that "the membranous septum develops improperly and becomes placed in a horizontal position, and is thus weakened in every way, and predisposed to the formation of aneurisms." In his own case the membranous septum was cribriform, and the hole communicated with numerous sacs in the medial segment of the tricuspid, and also bulged into the right atrium.  
the recent literature by Rudolf,^ Ivonstantinowitsch,^ Gierke,^ Schroeder,^
Jensen,'' and Rivet and Girard.^ We have had an opportunity of examining the specimen recorded by Rudolf, which is in the Museum of the
Toronto University. The patient was a girl of sixteen years, undeveloped
and cyanotic, who suffered from marked dyspnoea and died of pulmonary
tuberculosis. The auricular septum was absent and a large right was
divided from a smaller left auricular portion, with corresponding auricular
appendages, by a slight ridge on the posterior wall. A single large
bicuspid auriculoventricular orifice opened into the left side of a single
ventricle which gave off a large aorta and a smaller artery from its right
side, in transposed relations, and separated from the left part of the cavity
by a shallow muscular ridge, which lay in the posterior wall and marked
the site of the absent interauricular septum. The pulmonary orifice
was stenosed. The cases by Gierke and Konstantinowitsch were identical with this, except that the great vessels were not transposed
and in the former the pulmonary artery was atresic, in the latter the
aorta. In other cases the development of the aortic septum was completely arrested and a common arterial trunk replaced the two great
vessels.  


----


1 Virchows Arch., 1905, clxxxii, 168.  
Such aneurisms may give rise to marked and characteristic physical signs. This was true of two remarkable cases, one a heart which is in the McGill Museum, the other reported by Tate,<ref>Trans. Path. Soc. London, 1892, xliii, 36. VOL. IV - 24 </ref> in which a trumpetshaped tube, which formed the apex of a saccular pouching of the pars membranacea, projected behind and perforated the medial cusp of the tricuspid valve ; in the McGill specimen there was malignant endocarditis of the immediately adjacent tricuspid segment.  


2 Trans. Path. Soc. London, 1892, xliii, 34.


3 Anat. Soc. of Gt. Brit, and Ire., Nov., 1899.  
The relative frequency of aneurisms of the right aortic sinus of Valsalva and the probable dependence of these upon the juxtaposition of the pars membranacea of the right aortic cusp, has been discussed by Hart.^ The insertion of the medial cusp of the tricuspid just behind this point may further weaken this region by making it a seat of traction. It is not necessary to presuppose a congenital defect, although this may occur. In a case reported by Hale White^ an oval defect admitting a No. 10 catheter lay just below the right half of the anterior aortic cusp: its edges were thickened, but the septum around it for three-quarters of an
inch was thin and translucent, and the sinus of Valsalva above it was expanded into an aneurismal pouch, which protruded and burst into the right ventricle. The author thought that the whole septum between the lower part of the aorta and the base of the ventricles was abnormally thin.


' Prag. Med. Woch., 1906, p. 657. ^ Charite-Annalen, 1908, xxxii, 229.
==Defects in the Septum Elsewhere than at the Base==


6 Deut. Arch. J. klin. Med., 1911, ccv, 122 "> Giessen Thesis, 1912.  
These are usually multiple, and irregular or slit-like in form. They are of the greatest rarity. This is especially true of those low down in the septum.  


8 Arch, des Mai. du Coeur., November 11, 1913.


An anomalous entrance of the pulmonary veins into the superior cava,
innominate, hepatic, or other veins, instead of into the left auricle, was
noted in Wilson's case, and in most of those recently reported. In
that by Rivet and Girard, of a cyanotic infant aged twenty-five days
with polycythemia, these veins formed a common trunk which ended
in the lobus spigelii of the liver, and anastomosed here with the vense cavse
and portse. It seems possible that this anomaly may be the primary
one, at least as regards the non-development of the auricular septum, for
comparative anatomy shows that differentiation of the auricles is evolved
during the formation of a pulmonary circulation.
Fig. 29
"Incomplete double heart," showing (A) the interventricular septum, defective in its upper half;
B, a large, thick-walled aorta, arising from both ventricles above the defect; C, a single auriculoventricular cusp arising from both ventricles; D, stenosis of the conus of the pulmonary artery; R.A., the
enlarged right auricle. The right auricle and left ventricle are much hypertrophied and dilated; the
left auricle and sinus of the right ventricle rudimentary. The interauricular septum is defective in its
lower^alf. (From a specimen in the McGill Pathological Museum, presented by Dr. Andrewes.)
Such cases of pure biloculate heart are extremely rare. A more
common form is that in which the septa are partly developed, and an
incomplete division has occurred into four cavities, the organ still remaining two-chambered in the exercise of its function (incomplete double
heart). A good example is shown in a specimen in the McGill Museum,
presented by Dr. F. W. Andrewes (Fig. 29). Here the auricles are incompletely divided into a large right and a small left chamber, by a narrow
septum having a large defect above, multiple fenestrations, and a deeply,
concave lower free border (persistent ostium primum) . A thick muscular septum, one inch high, with rounded free border, projects upward from
the lower wall of the ventricle, partly dividing it into a small, thick-walled
right, and a capacious left ventricle. A dilated aorta rides above this
rudimentary septum and a narrow thin-walled bicuspid pulmonary arises
from a rudimentary conus. There is a common auriculo ventricular
orifice with five cusps, one of which is very strong and large and arises
from the opposing wall of either ventricle, stretching across above the
rudimentary septum and shielding the auriculoventricular orifice from
the two arterial ostia.
A third variation of biloculate or triloculate heart is presented by
cases of mitral or tricuspid atresia with absent or defective auricular
septum. In tricuspid atresia the ventricular septum has been developed,
but a defect remains at the base through which the blood passes from the
large left ventricle into the pulmonary artery through the persistent
bulbus, the sinus of the right ventricle having become obliterated. An
excellent example of the former condition (tricuspid atresia) is published
by Robertson^ under the title, cor biatriatrum triloculare. The auricular
septum was defective below (persistent ostium primum) and an anomalous
septum, evidently the persistent right valvula venosa, crossed the right
auricle from the Eustachian valve, and was inserted into the base of the
interauricular septum at the site of the tricuspid orifice, which was here
obliterated, possibly as a result of the insertion of the afiomalous septum
at this point. The great arterial trunks were transposed, the aorta
arising from the persistent bulbus arteriosus of the obliterated right
ventricle, which communicated with the cavity of the left ventricle by a
defect at the base of the otherwise fully developed interventricular
septum. Aplasia of the left chambers in mitral atresia is described by
Bernstein^ and by Girauld and Tissier.^ In the latter's case the left
auricle was tiny, and was separated from the left ventricle by a rudimentary bicuspid valve, and a large orifice united it with the greatly dilated
right auricle. The right ventricle was also enormous and gave off both
the aorta and the pulmonary artery in normal relations but separated
from each other by a thick muscular cushion (apparently marking the
conus of the pulmonary artery).
Biloculate heart is frequently displaced to the right side of the body,
in that type of dextrocardia that is apparently due to arrest of development. It is often associated with transposition of one or more viscera
or other serious defects. The spleen was absent in three of the cases.
Cor Biatriatrum Triloculare. - Absence of the ventricular with presence
of the auricular septum constitutes a three-chambered heart with two
auricles and the tricuspid and mitral orifices opening into a common
ventricle, from which (if the aortic septum develops), two arterial trunks
arise. Arnold^ reports a case of complete absence of the ventricular
septum, with auricular septum defective below (persistent ostium
primum), pulmonary atresia, dextrocardia, and absence of the spleen,
and adds a study of 30 case^ of cor biatriatrum triloculare. As in cor biloculare, obliteration of the right ventricle in tricuspid atresia (with
auricular septum present) is frequently reported as triloculate heart.
^Lancet, 1911, 180, p. 872.
2 Proc. Neiv York Path. Soc, 1906, N. S., vi, p. 29.
3 Bull. Soc. d'Obstet. de Paris, 1910, xiii, 420. ^ Virchows Arch., xlii.
A special type of anomaly has been established, of what is functionally
a cor biatriatrum triloculare, although four chambers exist, by a series
of cases recorded in which an anomalous septum cuts off from a common
ventricle a small chamber which lies at the base of the heart and gives
off one or the other of the great arterial trunks. Such a case, reported
and figured by Holmes,^ in 1824, the specimen from which is in the McGill
Fig. 30
Cor biatriatrum triloculare with malposed interventricular septum. Diagrammatic sketch by Prof.
R. Tait Mackenzie, showing course of blood and relation of cavities in Dr. Andrew Holmes' case of
displaced interventricular septum cutting off a small cavity which gives off the pulmonary artery. The
pale line shows venous, the dark line arterial blood. (From the Medical Museum of iMcGill University.)
Museum, is represented diagrammatically in Fig. 30. The auricles,
which were enormously dilated, especially the right, emptied their contents through their respective ostia into a common ventricle, which gave
off the aorta behind and somewhat to the left and communicated through
a diamond shaped opening in an anomalous septum with a small cavity
at its right upper angle of the common ventricle which gave off the
dilated pulmonary artery in its normal relation to the aorta. In eight other similar cases reported by Young/ Peacock,^ Rokitansky (2 cases),
Chiari, Theremin (Obs. 43), and ]Marchand,^ and in a specimen which
the writer has had the privilege of studying in the Museum of the Harvard Medical School, the aorta arose from the small chamber in front
and to the right, and the pulmonary artery from the common ventricle
behind it, the two vessels being in transposed relations. It has been
suggested by Keith that in these cases the anomalous septum is the
persistent lower orifice of the embryonic bulbus cordis, but study of both
the McGill and Harvard specimens lead us to the conclusion, that in these
specimens, at least, the strong muscular wall with a large defect at its
upper border through which the small cavity communicates with the
large common ventricle, is simply the malposed interventricular septum
itself, which has failed to unite with the aortic septum, and has been
carried around to the right in the further development of the heart.


----
----
^ Edin. Med. Chir. Soc, 1824, republished by M. E. Abbott, Montreal Med. Jour.,
1901.
Cor Biventriculare Triloculare. - When the auricular septum is absent
and the ventricular septum present, a heart with two ventricles and a
single auricle results. Such a case is reported by Williams.'^ All the
blood entered the common auricle through the superior vena cava (the
pulmonary veins having again an anomalous entrance).


Symptoms and Physical Signs. - In biloculate heart cyanosis is usually
<references/>
present from birth, and becomes very marked. The cases of Forster,^
Ramsbotham,^ and Crisp^ were all typical morbus cseruleus, dying,
respectively, at seventy-eight hours, ten days and ten weeks. On the
other hand symptoms may be moderate, as in Turner's case, in which
there was no cyanosis until just before death at the age of fifteen months.
Cases of cor biatriatrum triloculare present perhaps the best illustrations
we have that the adniixture of venous and arterial blood is compatible
with long life and with only slight disturbances of the circulation. Young's
patient, who died at thirty-nine years, cyanosis having developed only
within the last three weeks of life, and Peacock's almost identical case,
already noted, and that by Mann,^ dying at twenty-one years, are illustrations. Holmes' specimen (Fig. 30) was from a young man, aged
twenty-four years, in whom there was only moderate cyanosis and a
tendency to suffocative attacks. Physical signs may be prominent,
but cannot be said to be characteristic.


----
----

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Abbott ME. Congenital Cardiac Disease (1915) Osler & Mccrae's Modern Medicine 6, 2nd Edition.

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1915 Congenital Cardiac: Congenital Cardiac Disease | Heart Development | Literature | Etiology | Cyanosis | Classification | Pericardium | Heart Displacement | Whole Heart | Anomalous Septa | Interauricular Septum | Interventricular Septum | Absence of Cardiac Septa | Aortic Septum | Pulmonary Stenosis and Atresia | Pulmonary Artery Dilatation | Aortic Stenosis or Atresia | Primary Patency and Ductus Arteriosus | Aorta Coarctation | Aorta Hypoplasia | Diagnosis Prognosis and Treatment | Figures | Embryology History | Historic Disclaimer

Defects of the Interventricular Septum

The interventricular septum may be completely absent (cor biatriatrum triloculare), or it may be rudimentary, represented by a falciform process growing up from the lower and anterior wall of the ventricle, or localized defects may occur. These usually lie at its base, and are relatively common in association with other anomalies, but are not frequent alone. Defects elsewhere than at the base, whether alone or in combination, are among the rarest of cardiac anomalies.

1 Trans. Path. Soc, London, 1881, viii, 142.

2 Zeit.f. klin. Med., 1907, Ixii, 374. 3 Archiv. gen. de. med., 1880.

  • XIII Verh. Deut. Path. Gesell, 1909, p. 215.


Defects at the Base

The cases of congenital cardiac disease here studied have been drawn only from reliable sources, and all have postmortem reports attached, which should make them a fair index of relative frequency. It is therefore of interest to note that among them, while defects elsewhere in the septum are exceedingly rare, "pure" defects at the base are commoner than is usually supposed, and, in combination with other defects they rank as the most frequent cardiac anomaly.


Among the 631 cases, a defect at the base occurred 177 times, elsewhere than at the base, 12 times, making 189 cases, or 30 per cent. Of the 177 defects at the base, 34 were classed as the primary defect and 143 complicated other conditions. Of the 34 "primary" defects at the base, 8 were combined with rechtslage of the aorta, and in 1 of these there was also pulmonary hypoplasia; in another there was pulmonary hypoplasia without rechtslage; in 3 there was a patent ductus arteriosus, leaving 22 "pure" defects at the base unassociated with rechtslage or other anomaly except (in 5 cases) bicuspid or defective aortic or pulmonary valves


Of the 143 defects at the base complicating other anomalies, 75 were in cases of pulmonary stenosis or atresia, in 53 of which there was also rechtslage of the aorta. Of the remainder, 26 were in transposition of the great trunks, 3 in other defects complicated by rechtslage, and 13 in persistent truncus arteriosus. That is to say, in 42 other cases the defect was associated with an irregularity of development of the great trunks. In the remaining 26 of these 143 cases, the septal defect was associated with tricuspid atresia in 9 cases, with mitral atresia in 1, with aortic stenosis or dextrocardia in 2, and with partial defect of the aortic septum in two.

Pathogenesis

The combination of a defect of the interventricular septum vvith pulmonary stenosis and rechtslage of the aorta constitutes one of the commonest forms of congenital cardiac disease. So frequent is the combination that a causal connection between the three conditions has been sought, and rival theories as to which is the primary lesion have been suggested.


Much light was thrown upon this subject by Rokitansky, who concluded that non-inflammatory pulmonary stenosis, displacement to the right of the aorta, transposition of the great arterial trunks, and defects at the base Jf the interventricular septum were alike dependent upon a common cause, a deviation of the aortic, so that it failed to unite with the interventricular septum. He divided the latter into a part anterior, and one posterior to the undefended space, and classified defects at the base according as they lay in the anterior part of the anterior septum, in the posterior part of the anterior septum, or in the posterior septum. He pointed out that their usual situation was in the "posterior part of the anterior septum," that is, just anterior to the pars membranacea, in which case he believed they were practically invariably associated with a malposition of the arterial trunks. Keith has suggested that in the large number of cases in which a septal defect is associated with stenosis of the conus of the right ventricle the defect is a direct result of the inadequate expansion of the bulbus cordis to form the infundibuhim of the right ventricle.


Abbott 28.jpg

Fig. 28 Defect of the interventricular septum at undefended space. Heart of infant. No other anomaly. (From a specimen in the McGill Pathological Museum.)


Later advances in embryological knowledge show that the aortic septum is prolonged downward to assist in closing the interventricular septum at the undefended space, instead of the interventricular septum growing upward to form part of the aortic wall, as Rokitansky supposed. Moreover, independent defects of the interventricular septum in this situation, unassociated with any alterations in the relations of the great arterial trunks, and evidently not of inflammatory origin, may and do occur. This is so in the specimen seen in Fig. 28, and in cases reported by Orth,^ Arnold, Preisz,^ and Hart.^ Such conditions cannot be explained on Rokitansky's theory as due to deviation of the septum, or, a deficient expansion of the infundibuhim, but are due, as Keith himself points out, to a primary arrest of growth of unknown origin. In Hart's case an interesting associated anomaly, which may have had some bearing on the defect, was an anomalous cord which extended from the lower border of the conus of the right ventricle through the septal opening, to the anterior segment of the mitral valve.

Pathology

The commonest situation for the defect is directly beneath the aortic cusps and just anterior to the undefended space (Rokitansky's posterior part of the anterior septum) (Fig. 28). Here it lies with the fleshy muscular septum before it and the thin pars membranacea behind, and opens in the right heart beneath the septal cusp of the tricuspid, sometimes perforating this or bulging the (adherent) tricuspid leaflet before it, or opening into the right auricle directly above the base of the tricuspid, thus establishing a communication between this cavity and the two ventricles. IMore rarely the defect is placed farther forward in the septum in its anterior fleshy part, just behind the front wall of the heart, and is separated behind from the undefended space by a muscular column, opening into the conus of the right ventricle below the pulmonary valves. (Rokitansky's anterior part of the anterior septum). Examples are the cases by Coupland^ and Rolleston.^ Keith points out that in these cases, the defect is evidently in the musculature of the interbulbar septum, i. e., it is in that part of the interventricular septum which in the embryo formed the proximal part of the bulbus cordis before its division into the conus of the pulmonary artery and the vestibule of the aorta.



Defect of the interventricular septum at undefended space. Heart of infant. No other anomaly. (From a specimen in the McGill Pathological Museum.)


1 Virchoivs Archiv, 1880, Bd. 82, 529. 3 Virchows Archiv, 1905, Bd. 181, p. 7.3.

  • Trans. Path. Soc. London, 1879, xxx, 226.

= lUd., 1891, xlii, 65.


2 Ziegler's Beitrage, 1890, Bd. 7, 245.


^j66 diseases of the circulatory system


The defect varies in form and size from a pinhead perforation with tendinous edges, a round or oval hole admitting a goose-quill, knitting needle, index finger, etc., to a large triangular, semilunar, or crescentic space with thick-walled lower muscular border. Aneurismal pouching of the pars membranacea into the right ventricle may occur, with multiple sacculations perforated at their apices at one or more points (vide infra).


Quite frequently the margins of the defect with the adjacent valves are the seat of an acute inflammatory process which apparently originates at this point, because, as the seat of greatest strain,' it affords a site of lowered resistance. Such a case is reported by Gordon.^ In a boy aged five years who died of malignant endocarditis, a marked precordial thrill, and loud, harsh systolic murmur over the whole chest, with maximum intensity at the third and fourth left cartilages, indicated the septal defect. The autopsy showed a congenital opening, admitting a lead pencil, between the ventricles. The pulmonary valves and adjacent wall of the right ventricle were the seat of a number of large grayishgreen vegetations which extended below the level of the interventricular opening.


Moschcowitz^ related a very similar finding in a woman of twenty-nine years, who had had cardiac symptoms, palpitation, dyspnoea and occasional oedema of the legs since her fifteenth year, with exacerbation during the last four months, and symptoms of acute infection with chills and septic fever for one week. The blood cultures on one occasion showed Streptococcus viridans. At the autopsy both ventricles were hypertrophied, and the right also dilated, and there was a defect in the membranous septum admitting a lead-pencil. The pulmonary valves were replaced by large gray pedunculated vegetations, which extended up the wall of the pulmonary artery to its bifurcation, and had led to multiple emboli in either lung. The prolonged history of cardiac symptoms without adequate cause suggested a congenital lesion upon which the malignant endocarditis had been engrafted.


Dr. W. Thalhimer has sent me photographs of a heart from a cyanotic boy of nine years, with a huge septal defect and pulmonary stenosis in which a vegetative process had developed along the line of closure of the mitral and tricuspid valves. As there was no clinical history of an infective process, no Aschoff bodies in the myocardium, and no evidences of bacteria in the vegetations on microscopic examination, he is inclined to explain the vegetations on the ground of mechanical strain by the unnatural whirls in the blood stream, which have caused microscopic injuries of the valves and have thus given rise to an aseptic thrombosis. From a statistical study of the literature one is led to conclude that, at least in a large proportion of cases, the infective nature of the inflammatory process, so common in the neighborhood of cardiac defects, has been demonstrated.

1 Brit. Med. Journ., 1897, ii, 1174. ^ pj-^c. New York Path. Soc, 1914, xiv, 18.


In a case reported by Hebb[1] of a girl, aged eighteen years, whose heart showed a funnel-shaped defect at the base of the septum admitting a goose-quill, there were large vegetations bn the aortic, mitral, and pulmonary valves, and a 'patch of vegetations ivas also situated on the wall of the right ventricle opposite the defect. This observation, which is repeated in several other cases, as well as the frequent localization of the vegetations in the right ventricle affords an interesting proof of the fact that under normal conditions the current of blood flows from the left ventricle to the right through the defect. It is natural to suppose that this would be so, for the pressure in the systemic circulation is normally higher than it is in the pulmonary. Further anatomical confirmation of this direction of the stream is afforded by the oblique direction and funnelshape, with its larger end toward the left ventricle which the opening often assumes, and also by the not infrequent occurrence of patches of fibrosis on the opposite wall of the right ventricle.


Septal defects may exist without producing any change in the heart chambers, but they lead, still more frequently than do defects of the interauricular septum, to hypertrophy and dilatation of both ventricles. Where the defect is combined with rechtslage of the aorta, marked hypertrophy of the right ventricle is a constant feature. The pulmonary artery may be markedly dilated, as in 9 cases of the 34 "primary" defects at the base.


The distribution of the auriculoventricular junctional bundle in septal defects is of much interest, and has been investigated by Keith, Monckeberg, Morison,[2] and others. As is well known this bundle emerges from the auriculoventricular node close to the interauricular septum behind the medial cusp of the tricuspid valve, and divides into two branches, the left of which pierces the interventricular septum just in front of the pars membranacea, and passes downward superficially beneath the endocardium of the septum to be distributed to the papillary muscles and columnee carnese of this chamber, while the right branch runs, more deeply imbedded in the musculature of the right side of the septum, to the apex of the right ventricle. In most of the cases of septal defect examined there was surprisingly little change in this normal arrangement, the fibres streaming over the free border of the septum that formed the base of the defect toward the apices of their respective ventricles. In Morison's case the left branch was abortive. Keith described an abnormal band of "subaortic musculature," which may develop in the pars membranacea and overlie the bundle as it courses down the surface of the septum in the left ventricle, and in one of Monckeberg's cases of septal defect the bundle lay deeply in the musculature of the left septum instead of sub-endocardially as normally occurs. Recent investigations by Flack and Mall have shown that the interventricular septum is formed, not by a process growing upward from below, as Rokitansky supposed, but by a hollowing out of the spongy musculature of the embryonic ventricle to form the right and left chambers; the tip of the inferior septum, therefore, represents the wall of the lumen of the original cardiac tube, and this may account for the persistence of the bundle at this point in septal defects.

Symptoms and Physical Signs of Septal Defects

These may be absent and the defect discovered at autopsy. When cyanosis is present it may be slight or transient, appearing only on exertion, or terminal at the end of a long life, or, more rarely, and usually in those cases associated with rechtslage of the aorta, it may be well marked. Among the 34 "primary" defects at the base there was an entire absence of cyanosis in 17; it was slight in 5, moderate in 2, marked in 3, and terminal in 4 cases.


Physical signs may also be absent, as in two otherwise normal hearts with defects admitting a goose-quill, in the McGill Museum. On the other hand, physical signs atypical of acquired valvular disease are often present, even in the absence of symptoms, and are frequently sufficiently characteristic to permit of a diagnosis being made. In pronounced cases there may be visible pulsation and precordial bulging, and a thrill, usually systolic in time and diffuse over the precordium, or most marked over the middle of the cardia, is common and is more frequent than in auricular septal defects. A thrill was present in no less than 11 of the 34 cases of primary defects at the base; in 10 being systolic and in 1 a "continuous vibration." In 7 it was diffused over the whole cardia; in 3 it was most marked over its upper half; in 2 others it was localized at the apex.


A harsh, systolic murmur localized in the third or fourth left space is the most frequent evidence of the defect. Sometimes a very small hole may be accompanied by a very loud murmur. Roger described as characteristic a " single long, constant murmur beginning with systole and continuing through both heart sounds, localized in the upper third of the precordial region." Reiss mentions as typical a loud systolic murmur in the middle of the precordium, localized over the inner part of the third left space and the fourth rib.


A murmur apparently due to the defect was present in 26 of the 34 cases. In those in which its character was specified it was loud in 18, rough in 3, whistling, grating, harsh, sawing, each in 1, rasping in 3; in 3 instances it was blowing. It was systolic in rhythm in all 26 cases, and in 3 of these a diastolic murmur was present as well. The point of maximum intensity was 12 times in the upper third of the precordium near the left sternal border; of these, in 4 it was stated to be at the third left space, in 2 others also at the fourth left space, in 2 at the third costal cartilage (in 1 of which it was heard with equal intensity at the apex), in 2 at the pulmonary cartilage and second left space, and in 1 " over the middle of the sternum opposite the third left interspace." Besides these, in 2 other cases it was "along the left sternal border," "just to the left of the xiphoid cartilage," and "at the aortic cartilage;" in 2 (in 1 of which it was associated with rechtslage) it was "loudest at the apex," and in 4 it was diffuse over the precordium.


The murmur is usually transmitted downward along the left sternal border, and is frequently heard behind in the left infrascapular region. It may be diffused over the whole precordium, but is usually not heard in the axilla nor below the clavicle. In 6 cases in this series it was so loud as to be heard over the whole chest, and in 2 cases it could be traced into the vessels of the neck.


Eisenmenger^ claimed that a systolic murmur produced by the defect may be transmitted along the aorta, and thus be heard in the vessels of the neck, when pulmonary hypoplasia is also present, in which case the blood is diverted by the obstruction from its usual course into this vessel, and so passes from right to left into the aorta. In his own case, diagnosed by Schrotter before death, there was a defect admitting the thumb in the posterior part of the anterior septum, with rechtslage of the aorta and a dilated pulmonary artery. The patient, a man aged thirty-two years, had had cyanosis and dyspnoea from birth. There was visible precordial pulsation and bulging, and a systolic murmur over the middle of the heart transmitted everjn^v'here over its surface, but chiefly to the right and inferiorly, not heard above its base, along the course of the aorta nor in the pulmonary artery, the latter vessel being too far below the surface to transmit the sound.

Aneurisms of the Undefended Space

Cases have been recorded by Rokitansky, Zahn,[3] Hart,[4] IMacCallum,[5] and others, in which, in the absence of any evidence of endocarditis, sacculations, single or multilocular, of the membranous portion of the septum project into the right auricle above the medial cusp of the tricuspid, and in some cases extend also into the musculature of the interventricular septum. Malignant endocarditis of the bulging area is not infrequent and rupture into the right auricle may occur. On this ground it has been argued^ that these aneurisms are not of congenital origin, but are due to the action of the inflammatory process upon this delicate part of the septum. As was pointed out by Rokitansky, however, the reverse is probably true, the aneurism supplying a nidus of lowered resistance upon which an infective process has been secondarily engrafted. This point has been made the subject of an interesting communication by Mall,[6] who pronounces definitely upon the congenital and non-inflammatory origin of these aneurisms, and shows the cause to be a malposition of the inferior septum (inferior septum proper) so that "the membranous septum develops improperly and becomes placed in a horizontal position, and is thus weakened in every way, and predisposed to the formation of aneurisms." In his own case the membranous septum was cribriform, and the hole communicated with numerous sacs in the medial segment of the tricuspid, and also bulged into the right atrium.


Such aneurisms may give rise to marked and characteristic physical signs. This was true of two remarkable cases, one a heart which is in the McGill Museum, the other reported by Tate,[7] in which a trumpetshaped tube, which formed the apex of a saccular pouching of the pars membranacea, projected behind and perforated the medial cusp of the tricuspid valve ; in the McGill specimen there was malignant endocarditis of the immediately adjacent tricuspid segment.


The relative frequency of aneurisms of the right aortic sinus of Valsalva and the probable dependence of these upon the juxtaposition of the pars membranacea of the right aortic cusp, has been discussed by Hart.^ The insertion of the medial cusp of the tricuspid just behind this point may further weaken this region by making it a seat of traction. It is not necessary to presuppose a congenital defect, although this may occur. In a case reported by Hale White^ an oval defect admitting a No. 10 catheter lay just below the right half of the anterior aortic cusp: its edges were thickened, but the septum around it for three-quarters of an inch was thin and translucent, and the sinus of Valsalva above it was expanded into an aneurismal pouch, which protruded and burst into the right ventricle. The author thought that the whole septum between the lower part of the aorta and the base of the ventricles was abnormally thin.

Defects in the Septum Elsewhere than at the Base

These are usually multiple, and irregular or slit-like in form. They are of the greatest rarity. This is especially true of those low down in the septum.


  1. ↑ Trans. Path. Soc. London, 1897, xlviii, 41.
  2. ↑ Jour. Anat. and Physiol., 1913, xlvii, 459.
  3. ↑ Zeitschr. f. klin. Med., 1897, xxxii, Supp. Heft, 1.
  4. ↑ Virchows Arch., 1878, Ixxii, 206. » j^j^Z., 1905, clxxxi, 51.
  5. ↑ Johns Hopkins Hosp. Bull, 1900, xi, 69. 6 B^hl, Zeits.f. Biol, 1880, xvi.
  6. ↑ Anat. Record, June, 1912, p. 2921.
  7. ↑ Trans. Path. Soc. London, 1892, xliii, 36. VOL. IV - 24
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Abbott ME. Congenital Cardiac Disease (1915) Osler & Mccrae's Modern Medicine 6, 2nd Edition.

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