Original ArticlePapillary muscles of right ventricle—morphological variations and its clinical relevance☆,☆☆
Introduction
Papillary muscles play an important role in atrioventricular valve closure to maintain the unidirectional blood flow of the heart. Right ventricle accommodates three types of papillary muscles: anterior papillary muscle (APM), posterior papillary muscle (PPM), and septal papillary muscle (SPM). APM is the largest among all, which arises from right anterolateral ventricular wall, frequently being unique, and gives chordae to the anterior and the posterior valve leaflets. PPM appears from the myocardium below the inferior-septal commissure, is often bifid or trifid, and provides chordae tendon to the posterior and septal valve leaflets. Septal or medial papillary muscle, however, is the smallest but typical and arises from the posterior septal limbs of septomarginal trabeculae which usually supports septal and anterior leaflets via chordae, though the septal leaflet is often underpropped by chordae that directly arise from the ventricular septum. Usually, tricuspid valve function depends upon the maintenance of the proper spatial relationship between the papillary muscles, chordae tendineae, and valve leaflets through all phases of the cardiac cycle [1]. In a normal-sized heart, the long axis of papillary muscle is aligned almost right angle to the atrioventricular ring. This orientation provides a mechanical advantage as the tension developed within the papillary muscles that applied, is almost perpendicular to tricuspid valve leaflets [2]. In fact, papillary muscle plays a major role in right ventricular contraction by drawing the annulus towards apex, thereby shortening the long axis and chamber becomes spherical for ejecting blood [3]. Contraction of papillary muscles commences just prior to the onset of right ventricular systole so as to maximize coaptation of three cusps and reduce regurgitation [4]. When dynamic nature of this function is unsatisfactory, it leads to papillary muscle dysfunction [2].
The right side of heart as the cause of pulmonary emboli is not a new concept; various primary and secondary cardiac tumors have shown to be a potential source. Not only that, an aberrant papillary muscle complex is also thought to be the root of recurrent pulmonary embolus due to stasis of blood around these structures [5].
The focus of the study was to explore and document the architecture of right ventricular papillary muscles concerning numbers, shapes, positions, and arrangements and contrast the result with previous reports in an aim to overcome the lacunas.
Section snippets
Methods and materials
The study was carried out on 52 formalin-fixed human hearts obtained from cadavers who had passed away of nonvascular causes. Dissection was performed according to standard dissection techniques. Tricuspid valve was opened by giving an incision from right atrium to the apex along the acute margin of heart followed by an extension into anterior interventricular groove. Care was taken not to damage any papillary muscle of the right ventricle. Interior of the heart was washed to remove blood
Result
In the present study, number of papillary muscles was frequently seen as 3–4, though range was 2–7 irrespective of their positions within the ventricle. Conventional picture of right ventricular papillary muscles (one APM, one PPM, and one SPM) was seen only in 23.07% of specimens. APM was the most prominent in each specimen and appeared as single in 78.84% of cases. Double and triple APMs were present in 15.38% and 05.76% of cases, respectively. The PPM appeared as smaller: absent in 15.38%
Discussion
The interior of the right ventricle is as unique to each individual as one’s fingerprint [6]. There might be the presence or absence of any papillary muscle. Numerous publications [7], [8], [9] revealed that inside the normal right ventricle, considerable variation exists in the number of papillary muscles and their arrangements, shapes, origins, and attachments with valve leaflets. Comparing our result with those published in the literatures, we found few similarities but little differences,
Conclusion
By comparing and analyzing the morphometric data (Table 4) of present and previous study, we can draw the inferences that APM is more or less 100% present with high incidence of single belly; PPM is absent in 15.38%–25% of cases but more associated with multiple bellies. Striking point in present study is absence of SPM in 55.76% of cases. Not only that, the muscles are attached with leaflets not in conventional mode which may act as one of the adding factor by this study. Acquaintance with
References (21)
- et al.
Congenital mitral regurgitation from absence of the anterolateral papillarymuscle
Ann Thorac Surg
(2001) - et al.
Study on variations in the anterior papillary muscle of the right ventricle
IJIRD
(2014) - et al.
Functional terminology for the tricuspid valve
J Hear Valve Dis
(2006) Right ventricular variant and pulmonary embolism—association or coincidence?
Clin Med Insights Cardiol
(2010)- et al.
The tricuspid valve is bicuspid
J Heart Valve Dis
(1994) - et al.
Papillary muscles and tendinous cords of the right ventricle of the human heart morphological characteristics
Surg Radiol Anat
(2001) - et al.
Remarks on the morphology of the papillary muscles of the right ventricle
Folia Morphol
(2005) The medial papillary complex
Br Heart J
(1977)- et al.
Cadaveric study on anterior and posterior papillary muscles of tricuspid valve
Int J Anat Res
(2015)
Cited by (0)
- ☆
Conflicts of interest: We have nothing to declare about any conflicts of interest.
- ☆☆
Sources of research support, if any, including funding, equipment, and drugs: none to declare.