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Direct recording of heart sounds and murmurs from the epicardial surface of the exposed human heart
Direct
Recording
of the Exposed G. Magri, M.D., Turin, Italy
of Heart Human
Sounds
and Murmurs
From the Epicardial
Surface
Heart
E. Jona, M.D.,
D. Messina,
M.D.,
and A. Actis-Dato,
M.D.
Phonocardiography has been proved to be a very useful tool in cardiac diagnosis. Although by this method a good knowledge of acoustic phenomena of the heart has been achieved in the last twenty years, many problems still await solution. Thus, technical improvements in recording and filtration systems have been devised recently for a more nearly correct analysis of heart sounds and murmurs. A better approach to some clinical problems seems to be via intracardiac and direct epicardial phonocardiography. While the first method has been developed fully by several authors, the second, which was employed as early as 1917, by Wiggers and Dean, r has since been applied only in animals.2-4 The opening of the epicardial sac, as is usually done during heart surgery in man, has offered us an opportunity for the application of the second method in human beings. This study was planned with the hope that by recording the heart sounds and murmurs directly from the epicardial surface of the various chambers of the heart, valuable information could be obtained about the transmission and diffusion of acoustic phenomena and the site of origin of still ill-defined murmurs. Some partial results have been published already elsewhere.5z6 METHOD
AND
MATERIAL
A suitable transmission system which could be easily sterilized was adopted. A glass funnel (1 cm. in diameter) which could be kept adherent to the surface of the heart by the surgeon’s hand was connected to the microphone by a polyvinyl tubing, 45 cm. long, whose size (internal bore 0.6 cm. in diameter) was selected in accordance with the recommendations of Rappaport and Sprague.7,* The transmission characteristics of the whole system were tested against the vibrations of various frequency ranges (40 to 400 cycles per second) produced by a calibrated sound generator. A moderate loss of amplitude, but no gross distortion of the vibrations was noted. This can be shown even by standard phonocardiograms (Fig. 1).
Center School,
From the of the Turin, Received
“Istituto di Patologia “Clinica Chirurgica” Italy. for publication Nov.
Medica” (Prof. 35,
1958.
A.
(Prof. G. C. Dogliotti, Director). and M. Dogliotti, Director), University
the of
Heart Turin
Surgery Medical
The Sanborn speed was always purposes.
Twin-Beam phonocardiograph was used as the recording 75 mm. per second. .\ simultaneous electrocardiogram
Seventy-live patients stenosis plus insufficiency; stenosis; 7 had pulmonic artertosus.
Wig.
I.-Phonocardiograms chest:
B,
equipment; was taken
the paper for timing
were studied: .10 of the patiettts had pure mitral stenosis; 10 had mitral 5 had mitral stenosis plus tricuspid insufficient>,; 5 had aortic valvular \A\-ular stenosis; 12 had atrial septal defect; and 6 had patent ductus
with
recorded OVCP the apex: the tubing ronnerting
A. with the microphone applied th? glass funnel to t,he microphone.
directly
on
the
Before surgery a standard phonocardiogram \vas recorded in all patients on the clinical areas of auscultation, so that a comparison between the epicardial and precordial tracings would be possible. However, in such a comparison one has to take into account the modifications of the heart sounds induced by thorarotomy and anesthesia. As far as the absolute intensity is concerned, in general, at the surface of the heart the cardiac sounds are from 5 to 20 times louder than over the precordium. RESULTS
AND
COMMENT
Mitral Stenosis.-Forty-five patients were studied; they ranged in age from 18 to 44 years. In 30 of them there was no clinical evidence of other valvular lesions; in 10 there was some degree of mitral insufficiency; in 5 there was an The patients of the first group showed a associated tricuspid insufficiency.
DIRECT
EPICARDL4L
PHONOCARDIOGRAI’HY
ON
HlIMAN
HEdRT
451
typical precordial phonocardiogram, consisting of: (1) loud, snapping first sound, (2) loud, sometimes split second sound, (3) diastolic rumble, best recorded over the apex, followed by a “crescendo” presystolic murmur, when the sinus rhythm was maintained, and (4) opening snap of the mitral valve, widely recorded over the mid-precordium and pulmonic area. A moderate to loud systolic murmur over the apex and axilla was present in the patients of the second group. A blowing systolic murmur over the sternal area, increasing with deep inspiration, was recorded in the patients of the third group.
Fig. P.--Case of pure mitral stenosis. Pulmonary artery, and the aorta (from above). The beginning of the first sound is not clearly is Present over the Pulmonary artery, where aorta the second sound is split,
The tracings were recorded over the left ventricle. the Note the large diastolic vibrations over theleft ventricle. visible. A short early systolic murmur (ejection murmur) the! second sound is prolonged and very loud, Over the
452
MAGRI,
JONA,
MESSINA,
AND
ACTIS-DATO
Am. Heart J. March, 1959
Fig. 3.-Case of mitral stenosis plus tricuspid insuffiriency. The tracings were recorded left ventricle, the left atrium, the right atrium, and the pulmonary art,ery (from above), left ventricle the diastolic vibrations are larger than those of the first sound. Over the right very loud systolic murmur of tricuspid regurgitation is recorded. A short ejection early murmur is present over t,he pulmonary artery.
over the Over the atrium a systolic
&dAdu”deer “3’
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHT
ON HCMAN
HEART
4.53
During surgery, before mitral commissurotomy was performed, the following points on the surface of the heart were explored: (1) left wall of the left ventricle, (2) anterior wall of the left ventricle, near the A-V groove, (3) anterior wall of the left atrium, and (4) anterior wall of the pulmonary artery, just above the semilunar valve. The first sound was louder over the surface of the left ventricle than anywhere else. The second sound was loudest over the pulmonary artery; however, it was well recorded over the left atrium and ventricle. In some cases with split second sound, the aorta also could be reached with the exploring funnel. No difference between the aortic and pulmonic components over the two great vessels could be ascertained so that a criterion for their identification could be inferred. The opening snap of the mitral valve had its greatest intensity over the left atrium; however, in many instances it could be recorded with the same amplitude over the pulmonary artery. In most cases the vibrations of the diastolic rumble over the left ventricular wall were equal or even larger than the first sound (Fig. 2). This never happened in the precordial tracings. A possible explanation is that the lower pitched vibrations of the rumble are filtered out by the tissues of the chest wall. In the cases of associated valvular incompetence, a loud systolic murmur was constantly recorded over the left atrium; in some of them the murmur had the greatest intensity mostly over the posterior aspect of the left atrium. This could be due to the direction of the regurgitant flow and would explain the diffusion toward the axilla and the back of the apical systolic murmur of mitral insufficiency. When tricuspid insufficiency was present, a systolic murmur was recorded similarly over the right atrium (Fig. 3). In some cases of tight mitral stenosis, with enlarged pulmonary artery, a very loud systolic murmur was recorded over this vessel; the murmur sometimes spread over the left atrium and the aorta. It should be emphasized that many times the sounds and even the murmurs which originate in a definite site of the heart are clearly recorded over another structure which does not have any direct functional connection with the site of origin. For instance, the second sound is usually well transmitted to the left atrium, and the opening snap of the mitral valve to the pulmonary artery. As a matter of fact, both arterial trunks strictly contact the atria1 wall. This shows that inside the heart itself the diffusion of sounds can occur not only by way of the blood stream, but also by anatomic contiguity. Comparing the epicardial with the precordial phonocardiograms, we found that a good similarity exists between the left ventricular and the apical tracings, on the one hand, and between the pulmonary arterial tracing and the tracing recorded over the left intercostal space, on the other hand. No other consistent correspondence could be demonstrated between the precordial and free heart wall tracings. Pulmonic and Aortic Valvular Stenosis.-In the 7 casesof pulmonic valvular stenosis, a diamond-shaped loud systolic murmur was always reccrded over the trunk and the right pulmonary artery. This may be clue to contiguity, as stated
454
MAGKI,
JONA,
MESSINA,
.\ND
Am. Heart
ACTIS-DATO
March.
J. 1~59
above. In comparison with the tracings recorded over the trunk, those recorded distally along the right pulmonary artery show a progressively later appearance of the q.stolic murmur, which ultimately overlaps the second sound. This is possibly due to the fact that the second sound is transmitted along the vascular wall at the sound speed in a fluid milieu, while the murmur, rontinuousl) originated by a persistent turbulent flow distally from the stenotic valve, travels at a lower speed,which approximates that of the pulse wave.” A similar pattern was observed in the 5 cases of aortic valvular stenosis (Fig. 4).
Pig. $.--Case of aortir valvular stenosis and insufficiency. pulmonary artery and the aorta. Note the diamond-shaped The same pattern early diastolic murmur over thr aorta. pulmonary artery.
The systolic is present,.
tracings murmur with
were recorded over and the “decrescendo” lower intensity, over
the the
Atria1 Sepal Deject.-Direct phonocardiograms have been recorded in 12 cases of patency of the foramen ovale. In none of them was there pulmonary hypertension nor clinical evidence of pulmonary or tricuspid insufficiency. During surgery, before the defect was closed, the following points of the heart surface were explored: (1) the lateral wall of the right ventricle, (2) the anterior wall of the right atrium, (3) the anterior wall of the pulmonary trunk, (4) the right branch of the pulmonary artery, and (5) the wall of the pulmonary veins entering the left atrium.
Volume ~‘umher
57 3
DIKEC‘T
EPIC‘AKDL%L
PHONO(‘AKDIOGKXI’II~
ON
HVMAN
HEART
455
In all cases, conventional precordial phonocardiograms had shown: (1) a loud, harsh systolic murmur in the second and third intercostal spaces along the left sternal edge, (2) a prolonged, split second sound, and (3) low-pitched, low-amplitude diastolic vibrations, best recorded in the third and fourth inthere is no complete tercostal spaces at the mid-sternal line. In the literature, Some authors have attributed agreement about the origin of the last murmur.
The tracings were recorded over the right ventricle, t,he Fig. .i.--Case of atria1 septal defect. right atrium, and the pulmonary artery (from above). Note that the diastolic rumble is of much higher amplitude over the ventricle than over the atrium. A loud diamond-shaped systolic murmur is presnnt over the pulmonic trunk.
456
MAGRI,
_.-.
--.
.r-
of atria1 septal Fig. 6.-Case ventriclt 3, and the right pulmonary late appl earance of the diamond-shaped
JONA,
--I-‘-~‘-.
defect. artery
MESSINA,
AND
---r-----
The tracings (from above). systolic murmur,
ACTIS-DATC)
.-
were
-r---
recorded over the right Over the right pulmonary which overlaps the second
‘-
at,rium, artery, sound.
the right note the
~~12k~ “3’
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHY
ON
HIWAN
HEART
457
458
MAGRI,
JONA,
MESSINA,
AND
ACTIS-DATO
Am. Heart J. March, l’).iU
it to the passage of blood through the septal defect; however, most of them believe that the murmur is due to the eddies produced by the increased flow through the tricuspid valve, and indeed, it is often louder at the time of rapid ventricular filling. Low-pitched continuous vibrations created when the blood flows in the pulmonary veins (venous hum) do not seem, to us, to be clearly identifiable b> phonocardiographic recordings or by auscultation. The epicardial phonocardiograms have quite a different shape, depending on the zone explored. Over the right atrium and ventricle both the first and the second heart sounds were large and well identifiable. Over the same chambers the low-pitched diastolic vibrations appeared in those cases in which they were present also in the precordial tracings. ,\n accurate study of the timing of the diastolic rumble has not been possible because of the cardiac rate, but it was always louder over the right ventricle (Fig. 5). This could be assumed to indicate that it originates in the ventricular cavity. In none of our cases was it possible to record continuous low-pitched vibrations (venous hum) over the pulmonary veins. The very faint systolic vibrations over the right atrium and ventricle and over the aorta seem to be transmitted from the pulmonary artery, where a very loud diamond-shaped systolic murmur was recorded with the greatest intensity. This observation gives clear-cut proof that the systolic murmur of atria1 septal defect originates in the pulmonary artery,. It is interesting to observe that over the right pulmonaryartery, at some distance from the semilunar valves, the systolic murmur shows a definite delay-, as has been already described in the cases of pulmonary stenosis (Fig. 6).
Patent Ductus Arteriosus.-Direct epicardial phonocardiograms recorded in 6 cases of noncomplicated patent ductus arteriosus, without severe pulmonary hypertension, gave the following results : (1) The continuous “machinery” murmur was present, with greatest intensity over the pulmonary artery, at the same level or slightly below the opening of the ductus. A similar murmur of much lower intensity could be recorded over the aorta. (2) Low-pitched diastolic vibrations were observed over both ventricles, mostly over the right. This can be attributed to a relative tricuspid stenosis, due to the dilatation of the right chambers of the heart. Important changes were observed after the surgical closure of the ductus arteriosus: the continuous murmur disappeared completely, while a short and faint mid-systolic murmur was still present over the pulmonary artery. This murmur is likely to be produced by the persistent dilatation of the latter vessel. The diastolic rumble over the right ventricle was no longer recorded (Fig. 7). SI:MMAK\-
AND
CONCLUSIONS
Direct epicardial phonocardiography was performed in a series of 75 patients who underwent cardiac surgery. Some tentative conclusions drawn: (1) The absolute intensity of heart sounds and murmurs over the surface is 5 to 20 times greater than over the precordium. (2) Low-pitched tions are likely to be filtered out by the tissues of the thoracic wall.
selected can be cardiac vibra(3) The
Volume Number
57 3
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHY
ON
HlMAN
HEART
459
transmission of sounds and murmurs inside the heart itself and probably over the precordium takes places not only by way of the blood stream, but also by a topographical contiguity of different structures. (4) The site of origin of some controversial murmurs, such as the pulmonic systolic murmur in atria1 septal defect and the functional nature of the diastolic rumble in several conditions, including left-to-right shunts, could be ascertained. REFERENCES
1. 2. 3. 4. 5. 6. 7. 8. 9.
Wiggers,
C. J., and Dean, A. L.: The Nature and Time Relations of the Fundamental Heart Sounds, Am. J. Physiol. 42:476, 1917. Dock, W.: Mode of Production of the First Heart Sound, Arch. Int. Med. 51:737, 1933. Sloan, A. W., and Wishart, M.: Cardiac Ext ra S ounds in the Dog, J. Physiol. 122:737, 1953. Bertrand, C. A., Milne, I. G., and Hornick, R.: A Study of Heart Sounds and Murmurs by Direct Heart Recordings, Circulation 13:49, 1956. Magri, G., Jona, E., Gamna, G., Messina, D., and Guglielmini, G.: II fonocardiogramma epicardico dell’uomo, I : Nella stenosi mitralica, Minerva med. 49:36, 1958. Jona, E., Gamna, G., Messina, D., Dughera, L., and Actis-Dato, A.: I1 fonocardiogramma epicardico dell’uomo, II : Nella comunicazione interatriale, Minerva med. 49:47, 1958. Rappaport, M. B., and Sprague, H. B.: The Effect of Tubing Bore on Stethoscope Efficiency, AM. HEART J. 42:605, 19.51. Rappaport, M. B.: Personal communication. Kerr, W. J., and Harp, V. C., Jr.: Transmission of Murmurs, AM. HEART J. 37:100, 1949.
Recording
of the Exposed G. Magri, M.D., Turin, Italy
of Heart Human
Sounds
and Murmurs
From the Epicardial
Surface
Heart
E. Jona, M.D.,
D. Messina,
M.D.,
and A. Actis-Dato,
M.D.
Phonocardiography has been proved to be a very useful tool in cardiac diagnosis. Although by this method a good knowledge of acoustic phenomena of the heart has been achieved in the last twenty years, many problems still await solution. Thus, technical improvements in recording and filtration systems have been devised recently for a more nearly correct analysis of heart sounds and murmurs. A better approach to some clinical problems seems to be via intracardiac and direct epicardial phonocardiography. While the first method has been developed fully by several authors, the second, which was employed as early as 1917, by Wiggers and Dean, r has since been applied only in animals.2-4 The opening of the epicardial sac, as is usually done during heart surgery in man, has offered us an opportunity for the application of the second method in human beings. This study was planned with the hope that by recording the heart sounds and murmurs directly from the epicardial surface of the various chambers of the heart, valuable information could be obtained about the transmission and diffusion of acoustic phenomena and the site of origin of still ill-defined murmurs. Some partial results have been published already elsewhere.5z6 METHOD
AND
MATERIAL
A suitable transmission system which could be easily sterilized was adopted. A glass funnel (1 cm. in diameter) which could be kept adherent to the surface of the heart by the surgeon’s hand was connected to the microphone by a polyvinyl tubing, 45 cm. long, whose size (internal bore 0.6 cm. in diameter) was selected in accordance with the recommendations of Rappaport and Sprague.7,* The transmission characteristics of the whole system were tested against the vibrations of various frequency ranges (40 to 400 cycles per second) produced by a calibrated sound generator. A moderate loss of amplitude, but no gross distortion of the vibrations was noted. This can be shown even by standard phonocardiograms (Fig. 1).
Center School,
From the of the Turin, Received
“Istituto di Patologia “Clinica Chirurgica” Italy. for publication Nov.
Medica” (Prof. 35,
1958.
A.
(Prof. G. C. Dogliotti, Director). and M. Dogliotti, Director), University
the of
Heart Turin
Surgery Medical
The Sanborn speed was always purposes.
Twin-Beam phonocardiograph was used as the recording 75 mm. per second. .\ simultaneous electrocardiogram
Seventy-live patients stenosis plus insufficiency; stenosis; 7 had pulmonic artertosus.
Wig.
I.-Phonocardiograms chest:
B,
equipment; was taken
the paper for timing
were studied: .10 of the patiettts had pure mitral stenosis; 10 had mitral 5 had mitral stenosis plus tricuspid insufficient>,; 5 had aortic valvular \A\-ular stenosis; 12 had atrial septal defect; and 6 had patent ductus
with
recorded OVCP the apex: the tubing ronnerting
A. with the microphone applied th? glass funnel to t,he microphone.
directly
on
the
Before surgery a standard phonocardiogram \vas recorded in all patients on the clinical areas of auscultation, so that a comparison between the epicardial and precordial tracings would be possible. However, in such a comparison one has to take into account the modifications of the heart sounds induced by thorarotomy and anesthesia. As far as the absolute intensity is concerned, in general, at the surface of the heart the cardiac sounds are from 5 to 20 times louder than over the precordium. RESULTS
AND
COMMENT
Mitral Stenosis.-Forty-five patients were studied; they ranged in age from 18 to 44 years. In 30 of them there was no clinical evidence of other valvular lesions; in 10 there was some degree of mitral insufficiency; in 5 there was an The patients of the first group showed a associated tricuspid insufficiency.
DIRECT
EPICARDL4L
PHONOCARDIOGRAI’HY
ON
HlIMAN
HEdRT
451
typical precordial phonocardiogram, consisting of: (1) loud, snapping first sound, (2) loud, sometimes split second sound, (3) diastolic rumble, best recorded over the apex, followed by a “crescendo” presystolic murmur, when the sinus rhythm was maintained, and (4) opening snap of the mitral valve, widely recorded over the mid-precordium and pulmonic area. A moderate to loud systolic murmur over the apex and axilla was present in the patients of the second group. A blowing systolic murmur over the sternal area, increasing with deep inspiration, was recorded in the patients of the third group.
Fig. P.--Case of pure mitral stenosis. Pulmonary artery, and the aorta (from above). The beginning of the first sound is not clearly is Present over the Pulmonary artery, where aorta the second sound is split,
The tracings were recorded over the left ventricle. the Note the large diastolic vibrations over theleft ventricle. visible. A short early systolic murmur (ejection murmur) the! second sound is prolonged and very loud, Over the
452
MAGRI,
JONA,
MESSINA,
AND
ACTIS-DATO
Am. Heart J. March, 1959
Fig. 3.-Case of mitral stenosis plus tricuspid insuffiriency. The tracings were recorded left ventricle, the left atrium, the right atrium, and the pulmonary art,ery (from above), left ventricle the diastolic vibrations are larger than those of the first sound. Over the right very loud systolic murmur of tricuspid regurgitation is recorded. A short ejection early murmur is present over t,he pulmonary artery.
over the Over the atrium a systolic
&dAdu”deer “3’
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHT
ON HCMAN
HEART
4.53
During surgery, before mitral commissurotomy was performed, the following points on the surface of the heart were explored: (1) left wall of the left ventricle, (2) anterior wall of the left ventricle, near the A-V groove, (3) anterior wall of the left atrium, and (4) anterior wall of the pulmonary artery, just above the semilunar valve. The first sound was louder over the surface of the left ventricle than anywhere else. The second sound was loudest over the pulmonary artery; however, it was well recorded over the left atrium and ventricle. In some cases with split second sound, the aorta also could be reached with the exploring funnel. No difference between the aortic and pulmonic components over the two great vessels could be ascertained so that a criterion for their identification could be inferred. The opening snap of the mitral valve had its greatest intensity over the left atrium; however, in many instances it could be recorded with the same amplitude over the pulmonary artery. In most cases the vibrations of the diastolic rumble over the left ventricular wall were equal or even larger than the first sound (Fig. 2). This never happened in the precordial tracings. A possible explanation is that the lower pitched vibrations of the rumble are filtered out by the tissues of the chest wall. In the cases of associated valvular incompetence, a loud systolic murmur was constantly recorded over the left atrium; in some of them the murmur had the greatest intensity mostly over the posterior aspect of the left atrium. This could be due to the direction of the regurgitant flow and would explain the diffusion toward the axilla and the back of the apical systolic murmur of mitral insufficiency. When tricuspid insufficiency was present, a systolic murmur was recorded similarly over the right atrium (Fig. 3). In some cases of tight mitral stenosis, with enlarged pulmonary artery, a very loud systolic murmur was recorded over this vessel; the murmur sometimes spread over the left atrium and the aorta. It should be emphasized that many times the sounds and even the murmurs which originate in a definite site of the heart are clearly recorded over another structure which does not have any direct functional connection with the site of origin. For instance, the second sound is usually well transmitted to the left atrium, and the opening snap of the mitral valve to the pulmonary artery. As a matter of fact, both arterial trunks strictly contact the atria1 wall. This shows that inside the heart itself the diffusion of sounds can occur not only by way of the blood stream, but also by anatomic contiguity. Comparing the epicardial with the precordial phonocardiograms, we found that a good similarity exists between the left ventricular and the apical tracings, on the one hand, and between the pulmonary arterial tracing and the tracing recorded over the left intercostal space, on the other hand. No other consistent correspondence could be demonstrated between the precordial and free heart wall tracings. Pulmonic and Aortic Valvular Stenosis.-In the 7 casesof pulmonic valvular stenosis, a diamond-shaped loud systolic murmur was always reccrded over the trunk and the right pulmonary artery. This may be clue to contiguity, as stated
454
MAGKI,
JONA,
MESSINA,
.\ND
Am. Heart
ACTIS-DATO
March.
J. 1~59
above. In comparison with the tracings recorded over the trunk, those recorded distally along the right pulmonary artery show a progressively later appearance of the q.stolic murmur, which ultimately overlaps the second sound. This is possibly due to the fact that the second sound is transmitted along the vascular wall at the sound speed in a fluid milieu, while the murmur, rontinuousl) originated by a persistent turbulent flow distally from the stenotic valve, travels at a lower speed,which approximates that of the pulse wave.” A similar pattern was observed in the 5 cases of aortic valvular stenosis (Fig. 4).
Pig. $.--Case of aortir valvular stenosis and insufficiency. pulmonary artery and the aorta. Note the diamond-shaped The same pattern early diastolic murmur over thr aorta. pulmonary artery.
The systolic is present,.
tracings murmur with
were recorded over and the “decrescendo” lower intensity, over
the the
Atria1 Sepal Deject.-Direct phonocardiograms have been recorded in 12 cases of patency of the foramen ovale. In none of them was there pulmonary hypertension nor clinical evidence of pulmonary or tricuspid insufficiency. During surgery, before the defect was closed, the following points of the heart surface were explored: (1) the lateral wall of the right ventricle, (2) the anterior wall of the right atrium, (3) the anterior wall of the pulmonary trunk, (4) the right branch of the pulmonary artery, and (5) the wall of the pulmonary veins entering the left atrium.
Volume ~‘umher
57 3
DIKEC‘T
EPIC‘AKDL%L
PHONO(‘AKDIOGKXI’II~
ON
HVMAN
HEART
455
In all cases, conventional precordial phonocardiograms had shown: (1) a loud, harsh systolic murmur in the second and third intercostal spaces along the left sternal edge, (2) a prolonged, split second sound, and (3) low-pitched, low-amplitude diastolic vibrations, best recorded in the third and fourth inthere is no complete tercostal spaces at the mid-sternal line. In the literature, Some authors have attributed agreement about the origin of the last murmur.
The tracings were recorded over the right ventricle, t,he Fig. .i.--Case of atria1 septal defect. right atrium, and the pulmonary artery (from above). Note that the diastolic rumble is of much higher amplitude over the ventricle than over the atrium. A loud diamond-shaped systolic murmur is presnnt over the pulmonic trunk.
456
MAGRI,
_.-.
--.
.r-
of atria1 septal Fig. 6.-Case ventriclt 3, and the right pulmonary late appl earance of the diamond-shaped
JONA,
--I-‘-~‘-.
defect. artery
MESSINA,
AND
---r-----
The tracings (from above). systolic murmur,
ACTIS-DATC)
.-
were
-r---
recorded over the right Over the right pulmonary which overlaps the second
‘-
at,rium, artery, sound.
the right note the
~~12k~ “3’
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHY
ON
HIWAN
HEART
457
458
MAGRI,
JONA,
MESSINA,
AND
ACTIS-DATO
Am. Heart J. March, l’).iU
it to the passage of blood through the septal defect; however, most of them believe that the murmur is due to the eddies produced by the increased flow through the tricuspid valve, and indeed, it is often louder at the time of rapid ventricular filling. Low-pitched continuous vibrations created when the blood flows in the pulmonary veins (venous hum) do not seem, to us, to be clearly identifiable b> phonocardiographic recordings or by auscultation. The epicardial phonocardiograms have quite a different shape, depending on the zone explored. Over the right atrium and ventricle both the first and the second heart sounds were large and well identifiable. Over the same chambers the low-pitched diastolic vibrations appeared in those cases in which they were present also in the precordial tracings. ,\n accurate study of the timing of the diastolic rumble has not been possible because of the cardiac rate, but it was always louder over the right ventricle (Fig. 5). This could be assumed to indicate that it originates in the ventricular cavity. In none of our cases was it possible to record continuous low-pitched vibrations (venous hum) over the pulmonary veins. The very faint systolic vibrations over the right atrium and ventricle and over the aorta seem to be transmitted from the pulmonary artery, where a very loud diamond-shaped systolic murmur was recorded with the greatest intensity. This observation gives clear-cut proof that the systolic murmur of atria1 septal defect originates in the pulmonary artery,. It is interesting to observe that over the right pulmonaryartery, at some distance from the semilunar valves, the systolic murmur shows a definite delay-, as has been already described in the cases of pulmonary stenosis (Fig. 6).
Patent Ductus Arteriosus.-Direct epicardial phonocardiograms recorded in 6 cases of noncomplicated patent ductus arteriosus, without severe pulmonary hypertension, gave the following results : (1) The continuous “machinery” murmur was present, with greatest intensity over the pulmonary artery, at the same level or slightly below the opening of the ductus. A similar murmur of much lower intensity could be recorded over the aorta. (2) Low-pitched diastolic vibrations were observed over both ventricles, mostly over the right. This can be attributed to a relative tricuspid stenosis, due to the dilatation of the right chambers of the heart. Important changes were observed after the surgical closure of the ductus arteriosus: the continuous murmur disappeared completely, while a short and faint mid-systolic murmur was still present over the pulmonary artery. This murmur is likely to be produced by the persistent dilatation of the latter vessel. The diastolic rumble over the right ventricle was no longer recorded (Fig. 7). SI:MMAK\-
AND
CONCLUSIONS
Direct epicardial phonocardiography was performed in a series of 75 patients who underwent cardiac surgery. Some tentative conclusions drawn: (1) The absolute intensity of heart sounds and murmurs over the surface is 5 to 20 times greater than over the precordium. (2) Low-pitched tions are likely to be filtered out by the tissues of the thoracic wall.
selected can be cardiac vibra(3) The
Volume Number
57 3
DIRECT
EPICARDIAL
PHONOCARDIOGRAPHY
ON
HlMAN
HEART
459
transmission of sounds and murmurs inside the heart itself and probably over the precordium takes places not only by way of the blood stream, but also by a topographical contiguity of different structures. (4) The site of origin of some controversial murmurs, such as the pulmonic systolic murmur in atria1 septal defect and the functional nature of the diastolic rumble in several conditions, including left-to-right shunts, could be ascertained. REFERENCES
1. 2. 3. 4. 5. 6. 7. 8. 9.
Wiggers,
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