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Anatomy of the Cardiac Papillary Muscles
ARTICLE
Morphology of Papillary Muscles in Human Adults: A Cadaveric
Study
Mamatha Hosapatna, Anne D Souza, Aswin Das M, Supriya, Vrinda Hari Ankolekar, Antony Sylvan D Souza
Department of Anatomy, Kasturba Medical College, Manipal University, Manipal, Karnataka, India.
Corresponding author: Dr. Vrinda Hari Ankolekar
Email: [email protected]
Published: 10 July 2014
Ibnosina J Med BS 2014;6(4):168-172
Received: 03 January 2014
Accepted: 27 January 2014
This article is available from: http://www.ijmbs.org
This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Introduction: The papillary muscles (PM) play an
important role in ventricular overextension. The
variability in the number, shape and location of
papillary muscle of the right and the left ventricle is
important for the surgeon in reparative procedures,
papillary muscle dysfunction, mitral valve replacement
and use of mitral valve homograft for mitral/tricuspid
replacement. Materials and Methods: The study
was conducted using 15 formalin fixed adult human
hearts. The presence, number, shapes, length, number
of additional heads of the papillary muscles were
observed. The presence of moderator band (MB) was
noted and its level of attachment to the anterior PM
was observed. Results: Double anterior and posterior
PM were found in few cases. The length of PM was
longer in the left ventricle when compared to the
right ventricle which was statistically significant. In
the right ventricle cone-shaped PM was observed in
the majority of the cases whereas flat topped PM was
observed in 2 cases. In the left ventricle all the PM
were cone shaped. In majority of the cases (N=13) the
MB was attached to the lower third of the PM whereas
in one case each it was attached to the upper third
and to the middle third respectively. Conclusions:
The morphology and morphometry of the papillary
muscles of both ventricles and moderator band were
defined. These may help cardiac surgeons during
surgical procedures conducted for correction of their
defects.
Keywords: Papillary muscle, moderator band,
morphology, chordae tendineae
Introduction
The papillary muscles (PM) play an important role
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in valve function by drawing atrioventricular valve
annulus toward the apex, and prevent ventricular
overextension (1,2). Anterior papillary muscle (APM)
of the right ventricle is largest, posterior or inferior
papillary muscle (PPM) is frequently bifid or trifid.
Septal papillary muscle (SPM) is small. All the major
papillary muscles supply chordae to the adjacent
component of the cusp they support. The two papillary
muscles of the left ventricle supporting the cusps of
mitral valve also vary in length and breadth and may
be bifid. The papillary muscle and their chordae
regulate the closure of the AV valve during systole. The
moderator band (MB), also known as septomarginal
trabeculae extends from the right side of the ventricular
septum to the base of anterior papillary muscle. It
conveys the right branch of the atrioventricular bundle
and is presumed to prevent the over distention of the
right ventricle. The moderator band, or other large
trabeculations, is the major obstacle for the repair of
apical ventricular septal defects (3).
The relevance of chordo papillary variations in
rheumatic heart disease, reparative procedures,
papillary muscle dysfunction, mitral valve prolapse,
mitral valve replacement and use of mitral valve
Figure 1. Interior of right ventricle showing the papillary
muscles. APM- Anterior papillary muscle, PPM- Posterior
papillary muscle, L- Length of papillary muscle.
Ibnosina Journal of Medicine and Biomedical Sciences (2014)
169
homograft for mitral/tricuspid replacement have been
highlighted in previous studies (4-6). In particular,
the variability in the number, shape and location
of papillary muscles of the right ventricle has been
studied (7,8). Congenital variations are known to be
potential candidates for mechanical trauma leading
to tricuspid valve lesions (9,10). Damage to valves
or papillary muscles may occur after a trauma,
negatively affecting valve functions and creating
losses in the functional capacity of the body. Anatomic
variations of the right atrioventricular valve may
occur in association with other congenital anomalies
and syndromes. Also the number, length and shape
of the papillary muscles are variable. This can be
of clinical significance since the papillary muscles
play an important role in the contraction of the right
ventricle and in the closure of the tricuspid valve so as
to prevent ventricular blood from passing back into the
right atrium (11). Anatomical studies on morphology
of papillary muscles of heart are rare. For this reason,
the morphology and morphometry of the papillary
muscles of both ventricles and moderator band were
studied to help the surgeons during surgical procedures
conducted for correction of their defects.
Material and Methods
The study was conducted using 15 formalin fixed
adult human hearts procured from the Department of
Anatomy, Kasturba Medical College, Manipal, India.
The ventricles were opened using incisions along the
anterior wall to expose the interior. The presence,
number and shape of the PM were observed. The
length of the PM was measured from the tip to the
basal attachment (Figure 1). The number of additional
heads was also noted. The shape at the tip was
classified as conical or flattened. The presence of MB
was noted and its level of attachment to the anterior
PM was observed. The attachment was classified as to
the upper, middle or lower third. SPSS version 16 was
used for the statistical analysis.
Results
The study was done on 15 adult human hearts for the
morphology of papillary muscles. Double APM and
PPM were also found in few cases, the frequency
Hosapatna M et al 170
Anatomy of the Cardiac Papillary Muscles
Table 1. Mean and standard deviations of the length of papillary muscles length in cm (N=15)
Papillary muscle by location
Right
Left
Anterior papillary muscle (APM)
1.30 ± 0.40
1.63 ± 0.50
Posterior papillary muscle (PPM)
0.98 ± 0.40
2.14 ± 0.60
Septal papillary muscle (SPM)
0.55 ± 0.20
-
Figure 2. Interior of the right ventricle showing the bifid PPM
(1a) and bifid APM (1b). PPM- Posterior papillary muscle, APMAnterior papillary muscle.
distribution of which is shown in Figure 1. The chordae
tendineae from the septal leaflet of tricuspid valve were
attached directly to the ventricular wall whereas in 5
hearts single SPM was found. The mean and standard
deviations of the lengths of PM is shown in table 1.
Student t-test was used to compare the mean lengths
of right and left side. The mean length of PM was
longer in the left ventricle when compared to the right
ventricle which was statistically significant (p=0.04).
In the right ventricle cone shaped PM were observed
in the majority of the cases (N=13) whereas flat topped
PM was observed in 2 cases. In the left ventricle all
the PM were cone shaped. The PM were also observed
for the presence of multiple heads. Figure 2a and 2b
shows bifid PPM and bifid APM respectively. The
frequency distribution of specimens having bifid
Figure 3. Interior of right ventricle showing the moderator band
attached to the lower third of the anterior papillary muscle. APMAnterior papillary muscle, MB- Moderator band.
PM is shown in Figure 2. The bifid PM were more
commonly observed in the left ventricle. The MB
was observed for its attachment to the anterior PM. In
majority of the cases it was attached to the lower third
of the PM (N=13) (Figure 3) whereas in one case each
it was attached to the upper third and to the middle
third respectively.
Discussion
The present study was undertaken to describe the
morphology of papillary muscles in cadaveric
hearts. Skwarek et al in their study subdivided the
morphology of the papillary muscles into 16 subtypes
(12). According to Aktas et al the papillary muscles
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were conical projections of the ventricular muscle
the apices which afforded attachment to the chordae
tendineae. Although the papillary muscles presented
great variability in number, with a minimum of 2 and a
maximum of 9, in the right ventricle there were usually
3 papillary muscles, anterior (APM) posterior (PPM)
and SPM that corresponded nominally to the leaflets
of the tricuspid valve. He found single APM in 80.5%
of the cases (161 cases) and a double APM in 19.5%
(39 cases). Double APM was found associated with the
lack of SPM in 4 cases (2.5%) and with the presence
of a muscular bridge connecting the two heads (13).
In our study the number of heart specimens having
double APM in right and left ventricles were 3 and 2
specimens, double PPM in right and left ventricles were
in 8 and 6 specimens respectively. Study conducted
by Aktas et al the single papillary muscles were either
conical, mamillated, flat topped, grooved, stepped,
wavy, arched, sloped or saucerized (13). Victor et al
classified the single papillary muscles according to the
shape as conical, mammillated, flat topped, grooved,
stepped, wavy, arched, sloped or saucerized. (14)
A study done by Gunnal et al highlighted 4 types of
shapes of papillary muscles named as conical, broadapexed, pyramidal and fan-shaped (15). In our study
cone shaped PM were observed in the majority of the
cases (N=13) whereas flat topped PM was observed in
2 cases in the right ventricle. In the left ventricle all the
PM were cone shaped. According to Aktas et al a single
APM was found with a length ranging between 11.45
and 45.3 mm (mean 20), and this was greater than that
of a double one ranging between 7.2 and 25.15 mm
(mean 15) (13). In our study the mean length of APM
was 1.3±0.4 cm and 1.63±0.5 cm on right and left side
respectively. The mean length of PPM was 0.98±0.4
cm and 2.14±0.6 cm on right and left side respectively.
The mean length of SPM was 0.55±0.2 cm and on right
side. A study done by Aktas et al the double headed
APM (N: 39) was associated with the presence of at
least one SPM in 32 hearts, 82.1% and were distributed
as follows: 12 hearts presented one SPM (30.8%), 9
presented 2 SPM (23.1%), 6 presented 3 SPM (15.4%)
and 5 presented 4 SPM (12.8%). The double headed
APM was not associated with the existence of the
Ibnosina Journal of Medicine and Biomedical Sciences (2014)
171
SPM in 7 hearts (17.9%) (13). In our study the double
headed APM was observed in 4 and 6 specimens on
the right and left side respectively. The double headed
PPM was observed in 4 and 9 specimens on the
right and left side respectively. According to Bojsenmoller et al the right bundle branch of the conducting
system in 19 pig hearts was traced through part of the
interventricular septum and through the moderator
band as far as the base of the anterior papillary muscle
(16). In our study the moderator band was observed
for its attachment to the anterior APM. In majority
of the cases it was attached to the lower 3rd of the
APM (N=13) whereas in one case it was attached
to the upper third and in other it was attached to the
middle third. The morphology of moderator band
might help in understanding and surgical corrections
of the defects pertaining to interventricular septum.
The literature on the morphology and morphometry of
PM is very limited. So the present study is an initial
effort to highlight the same.
In conclusion, the length of the PM was longer in
the left ventricle than that in the right. The PPM are
more commonly found to be double. Bifid heads were
commonly observed in left PPM. The morphology
and morphometry of the papillary muscles of both
ventricles and moderator band were studied to help
the surgeons during surgical procedures conducted for
correction of their defects.
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