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Heart (British Cardiac Society) Apr 2023It is now accepted that the mitral valve functions on the basis of a complex made up of the annulus, the leaflets, the tendinous cords and the papillary muscles. So as... (Review)
Review
It is now accepted that the mitral valve functions on the basis of a complex made up of the annulus, the leaflets, the tendinous cords and the papillary muscles. So as to work properly, these components must combine together in harmonious fashion. Despite the features of the arrangement of each component having been the focus of anatomical investigation for centuries, controversies still exist in their inter-relations and how best to describe them. To a large extent, the ongoing problems reflect the fact that, again for centuries, morphologists when describing the heart have ignored the rule that its components should be described as seen in the body during life. Failure to use attitudinally appropriate descriptions underscores a particular current issue, namely the influence of the so-called disjunction within the atrioventricular junction as a potential substrate for leaflet prolapse or malignant arrhythmias. With these difficulties in mind, we have reviewed how the components of the valvar complex can best be described when comparing direct images with those obtained using three-dimensional techniques now used for clinical imaging. We submit that these show that the skirt of leaflet tissue is best described as having aortic and mural components. When the hinge of the mural leaflet is assessed within the overall atrioventricular junction, the so-called disjunction is ubiquitous, but not always in the same place. We further suggest that its significance will best be determined when clinicians describe its presence using attitudinally appropriate terms.
Topics: Humans; Mitral Valve; Mitral Valve Insufficiency; Mitral Valve Prolapse; Papillary Muscles; Arrhythmias, Cardiac
PubMed: 36585240
DOI: 10.1136/heartjnl-2022-322043 -
Cureus Feb 2022Introduction A normal atrioventricular valve complex of the heart consists of the atrioventricular (A-V) ring, cusps, chordae tendineae, and papillary muscles. The right...
Introduction A normal atrioventricular valve complex of the heart consists of the atrioventricular (A-V) ring, cusps, chordae tendineae, and papillary muscles. The right ventricle contains three while the left ventricle contains only two papillary muscles, which are named according to their location. A thorough understanding of the normal anatomy as well as possible variations can help surgeons in various corrective surgeries involving papillary muscles. Material & methods The study included 50 formalin-preserved hearts procured from human cadavers of unknown age and cause of death. The number of papillary muscles along with their shape, size, and pattern were noted separately for each ventricle. Data were analyzed using SPSS Version 21.0 (IBM Corp., Armonk, NY). Results The left and right ventricles contained two and three papillary muscles, respectively, in all the hearts. In the right ventricles, conical shape and the single base and divided apex (SBDA) pattern were found to be most prevalent. Anterior papillary muscles exhibited the mean length of 12.71±3.81 and 16.41±4.33 in the right and left ventricles, respectively. Similarly, posterior papillary muscles exhibited a mean length of 12.40±3.03 and 14.64±3.92 in the right and left ventricles, respectively. Both differences were found to be statistically significant Conclusion For the appropriate functioning of valves, both anatomical and mechanical coherence of the papillary muscles is required. A very keen understanding of this valvular complex is thus essential for anatomists, physiologists, and cardiologists to deal with normal as well as pathological valvular conditions.
PubMed: 35382408
DOI: 10.7759/cureus.22722 -
Pacing and Clinical Electrophysiology :... Apr 2022Catheter ablation of papillary muscle ventricular arrhythmias (PM-VAs) has been associated with unsatisfactory results. Features that may affect acute and long-term...
BACKGROUND
Catheter ablation of papillary muscle ventricular arrhythmias (PM-VAs) has been associated with unsatisfactory results. Features that may affect acute and long-term procedural outcomes are not well established.
OBJECTIVE
To systematically review the available data in the literature assessing efficacy and safety of PM-VAs catheter ablation.
METHODS
An online search of PubMed, Cochrane Registry, Web of Science, Scopus and EMBASE libraries (from inception to March 1, 2021) was performed, in addition to manual screening. Twenty-one observational noncontrolled case-series were considered eligible for the systematic review, including 536 patients.
RESULTS
Postero-medial PM harbored 60.8% of PM-VAs, while antero-lateral PM and right ventricular PMs 34.9% and 4.3% of cases, respectively. The mean acute success rate of the index ablation procedure was 88.1% (95% CI 82.8% to 91.9%, p < .001, I 0%). After a mean follow-up period of 15.5 ± 17.4 months, pooled long-term arrhythmia-free rate was 69.2%, while the pooled long-term success rate after multiple ablation procedure was 84.9%. Overall, procedure complications occurred in nine patients (1.7%) and no procedure-related deaths were reported. The use of intracardiac echocardiography (ICE) as well as contact force sensing (CFS) and irrigated catheters during ablation was associated with higher rates of arrhythmia-freedom at long-term follow-up.
CONCLUSIONS
Catheter ablation is an effective and safe strategy for PM-VAs, with an acute success rate of 88.1%, a long-term success rate of 69.2%, with a relatively low procedural complication rate. The use of ICE, irrigated catheters and catheters with CFS capability was associated with higher rates of arrhythmia-freedom at long-term follow-up.
Topics: Catheter Ablation; Heart Ventricles; Humans; Papillary Muscles; Tachycardia, Ventricular; Treatment Outcome; Ventricular Premature Complexes
PubMed: 35147225
DOI: 10.1111/pace.14462 -
JTCVS Open Sep 2021Undersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation lacks durability, as it forces leaflet coaptation without relieving the sub-leaflet...
BACKGROUND
Undersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation lacks durability, as it forces leaflet coaptation without relieving the sub-leaflet tethering forces. In this biomechanical study, we demonstrate that papillary muscle approximation (PMA) prior to UMA can drastically relieve tethering forces and improve valve function, without the need for significant annular downsizing.
METHODS
An model of functional mitral regurgitation (FMR) was used, in which pig mitral valves were geometrically perturbed to induce FMR, and the repairs were performed. Nine pig mitral valves were studied as follows: normal(baseline), functional mitral regurgitation (FMR), true-sized annuloplasty to 30mm (TSR), and undersized annuloplasty to 26mm (DSR); and concomitant papillary muscle approximation (PMA) at both ring sizes. Mitral regurgitation, valve kinematics, and chordal forces were measured and compared between groups.
RESULTS
FMR geometry induced a 16.31±7.33% regurgitant fraction, compared to none at baseline. 30mm/TSR reduced regurgitation to 6.05±5.63% and a 26mm/DSR to 5.06±6.76%. Addition of papillary muscle approximation prior to either rings, reduced regurgitation to 3.87±6.79% with the true sized ring (TSR+PMA), and 3.71±6.25% with the downsized ring (DSR+PMA). Peak anterior and posterior marginal chordal forces were elevated to 0.09±0.1N and 0.12±0.1N respectively with FMR, which were not reduced by annuloplasty of either sizes. Addition of PMA, reduced the forces significantly to 0.23±0.02N and 0.51±0.04N.
CONCLUSION
This biomechanical study, demonstrates that papillary muscle approximation relieves tethering forces and when added to annuloplasty, and mobilizes the leaflets to achieve a good valve closure. Such a result could be achieved without the need for extensive annular downsizing.
PubMed: 35299626
DOI: 10.1016/j.xjon.2021.04.008 -
JACC. Clinical Electrophysiology Jul 2022The right ventricular moderator band and papillary muscle (RV MB-PM) complex is an uncommon source of ventricular arrhythmias (VAs). Success rates following the ablation...
BACKGROUND
The right ventricular moderator band and papillary muscle (RV MB-PM) complex is an uncommon source of ventricular arrhythmias (VAs). Success rates following the ablation of intracavity structures are lower than for other sites of origin of VAs because of challenging catheter stability and a tendency for hemodynamically unstable automaticity when radiofrequency (RF) is delivered.
OBJECTIVES
This study sought to describe the institutional experience of RV MB-PM VAs across a 2-year period and compare the outcomes from ablations performed using RF ablation and cryoablation.
METHODS
Electronic health records of patients who underwent catheter ablation of RV MB-PM arrhythmias between January 2018 and November 2021 were reviewed, including imaging, intraprocedural data, and follow-up.
RESULTS
Eleven patients underwent ablation of RV MB-PM arrhythmias throughout the duration of the study. Five patients underwent catheter ablation with RF, and 6 patients underwent cryoablation. Three patients in the cryoablation group had previous attempted ablation with RF. Four patients in the RF group and 4 patients in the cryoablation group had structurally abnormal hearts. Acute VA suppression was achieved in 4 of 5 patients with RF and 6 of 6 patients with cryoablation. During follow-up, the rate of arrhythmia recurrence was lower in the cryoablation group (HR: 0.12; 95% CI: 0.016-0.90; P = 0.0396).
CONCLUSIONS
Compared to RF, cryoablation offers improved catheter stability and reduced propensity for automaticity during ablation. The use of cryoablation as a first-line strategy is reasonable when RV MB-PM origin of premature ventricular contractions is suspected.
Topics: Catheter Ablation; Cryosurgery; Humans; Papillary Muscles; Tachycardia, Ventricular; Ventricular Premature Complexes
PubMed: 35863811
DOI: 10.1016/j.jacep.2022.03.011 -
The Annals of Thoracic Surgery May 2021The anomalous insertion of papillary muscle directly into the anterior mitral leaflet is a rare congenital anomaly concomitant with hypertrophic cardiomyopathy. We...
BACKGROUND
The anomalous insertion of papillary muscle directly into the anterior mitral leaflet is a rare congenital anomaly concomitant with hypertrophic cardiomyopathy. We herein report our surgical technique, which is designed to relieve left ventricular obstruction and preserve the mitral valve and subvalvular apparatus.
METHODS
Among 38 patients who underwent septal myectomy from 2007 to 2020, 4 had an anomalous mitral subvalvular apparatus with papillary muscle with direct insertion into the anterior mitral leaflets. In all cases, mitral valve repair was accomplished with excision and reconstruction of all anomalous papillary muscles, concomitant with septal myectomy. In another 34 patients, 20 cases needed mitral valve repair with regard to systolic anterior motion by hypertrophic cardiomyopathy. The comparison study was conducted between the anomalous papillary muscle group (group A) and the others (group B).
RESULTS
There was no early or late death in group A, and there were 3 early deaths and 2 late deaths in group B. The mean peak gradient in the left ventricle was significantly decreased in both groups. Mitral valve regurgitation grade was also significantly decreased from 3 to 0.5 without valve replacement in group A, and from 2 to 0.6 in group B. Six patients needed mitral valve replacement because of the thickness of anterior mitral leaflet in group B.
CONCLUSIONS
Hypertrophic obstructive cardiomyopathy associated with the anomalous insertion of papillary muscle can be successfully treated without mitral valve replacement. Excision and reconstruction with the anomalous papillary muscle seems to be a feasible operation to reduce mitral regurgitation and relieve outflow tract obstruction.
Topics: Aged; Aged, 80 and over; Cardiac Surgical Procedures; Cardiomyopathy, Hypertrophic; Female; Humans; Male; Middle Aged; Mitral Valve; Papillary Muscles; Retrospective Studies
PubMed: 32980328
DOI: 10.1016/j.athoracsur.2020.07.031 -
JTCVS Open Mar 2021The exact geometric pathogenesis of leaflet tethering in ischemic mitral regurgitation (IMR) and the relative contribution of each component of the mitral valve complex...
BACKGROUND
The exact geometric pathogenesis of leaflet tethering in ischemic mitral regurgitation (IMR) and the relative contribution of each component of the mitral valve complex (MVC) remain largely unknown. In this study, we sought to further elucidate mitral valve (MV) leaflet remodeling and papillary muscle dynamics in an ovine model of IMR with magnetic resonance imaging (MRI) and 3-dimensional echocardiography (3DE).
METHODS
Multimodal imaging combining 3DE and MRI was used to analyze the MVC at baseline, 30 minutes post-myocardial infarction (MI), and 12 weeks post-MI in ovine IMR models. Advanced 3D imaging software was used to trace the MVC from each modality, and the tracings were verified against resected specimens.
RESULTS
3DE MV remodeling was regionally heterogenous and observed primarily in the anterior leaflet, with significant increases in surface area, especially in A2 and A3. The posterior leaflet was significantly shortened in P2 and P3. Mean posteromedial papillary muscle (PMPM) volume was decreased from 1.9 ± 0.2 cm at baseline to 0.9 ± 0.3 cm at 12 weeks post-MI ( < .05). At 12 weeks post-MI, the PMPM was predominately displaced horizontally and outward along the intercommissural axis with minor apical displacement. The subvalvular contribution to tethering is a combination of unilateral movement, outward displacement, and degeneration of the PMPM. These findings have led to a proposed new framework for characterizing PMPM dynamics in IMR.
CONCLUSIONS
This study provides new insights into the complex interrelated and regionally heterogenous valvular and subvalvular mechanisms involved in the geometric pathogenesis of IMR tethering.
PubMed: 36003177
DOI: 10.1016/j.xjon.2020.10.007 -
Methods in Molecular Biology (Clifton,... 2021Isolated cardiac tissue allows investigators to study mechanisms underlying normal and pathological conditions, which would otherwise be difficult or impossible to...
Isolated cardiac tissue allows investigators to study mechanisms underlying normal and pathological conditions, which would otherwise be difficult or impossible to perform in vivo. In contrast to ventricular muscle strip preparations, papillary muscles can be prepared without severely damaging the muscle tissue. In this preparation, the isolated papillary muscle is fixed in an environmentally controlled organ bath chamber and electrically stimulated. The evoked twitch force is recorded using a pressure transducer, and parameters such as twitch force amplitude and twitch kinetics are analyzed. A variety of experimental protocols can be performed to investigate the calcium- and frequency-dependent contractility as well as dose-response curves of contractile agents, as well as simulation of pathologic conditions such as acute cardiac ischemia. Mouse papillary muscle preparations have long been the mainstay for studying interactions between intracellular calcium regulation and contractile responses under a number of simulated pathophysiological conditions. These studies are often used to complement in vitro studies performed using isolated neonatal rat cardiac myocytes. In this procedure, we describe how neonatal rat papillary muscles can also be prepared for use in contractile studies.
Topics: Animals; Animals, Newborn; Electric Stimulation; Myocardial Contraction; Myocytes, Cardiac; Papillary Muscles; Rats; Surgical Equipment
PubMed: 34331240
DOI: 10.1007/978-1-0716-1480-8_4 -
European Journal of Cardio-thoracic... Jun 2022
Topics: Humans; Mitral Valve; Mitral Valve Annuloplasty; Mitral Valve Insufficiency; Papillary Muscles
PubMed: 35678572
DOI: 10.1093/ejcts/ezac339 -
Diagnostics (Basel, Switzerland) Apr 2023(1) Background: With the conventional contour surface method (KfM) for the evaluation of cardiac function parameters, the papillary muscle is considered to be part of...
(1) Background: With the conventional contour surface method (KfM) for the evaluation of cardiac function parameters, the papillary muscle is considered to be part of the left ventricular volume. This systematic error can be avoided with a relatively easy-to-implement pixel-based evaluation method (PbM). The objective of this thesis is to compare the KfM and the PbM with regard to their difference due to papillary muscle volume exclusion. (2) Material and Methods: In the retrospective study, 191 cardiac-MR image data sets (126 male, 65 female; median age 51 years; age distribution 20-75 years) were analysed. The left ventricular function parameters: end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined using classical KfW (syngo.via and cvi42 = gold standard) and PbM. Papillary muscle volume was calculated and segmented automatically via cvi42. The time required for evaluation with the PbM was collected. (3) Results: The size of EDV was 177 mL (69-444.5 mL) [average, [minimum-maximum]], ESV was 87 mL (20-361.4 mL), SV was 88 mL and EF was 50% (13-80%) in the pixel-based evaluation. The corresponding values with cvi42 were EDV 193 mL (89-476 mL), ESV 101 mL (34-411 mL), SV 90 mL and EF 45% (12-73%) and syngo.via: EDV 188 mL (74-447 mL), ESV 99 mL (29-358 mL), SV 89 mL (27-176 mL) and EF 47% (13-84%). The comparison between the PbM and KfM showed a negative difference for end-diastolic volume, a negative difference for end-systolic volume and a positive difference for ejection fraction. No difference was seen in stroke volume. The mean papillary muscle volume was calculated to be 14.2 mL. The evaluation with PbM took an average of 2:02 min. (4) Conclusion: PbM is easy and fast to perform for the determination of left ventricular cardiac function. It provides comparable results to the established disc/contour area method in terms of stroke volume and measures "true" left ventricular cardiac function while omitting the papillary muscles. This results in an average 6% higher ejection fraction, which can have a significant influence on therapy decisions.
PubMed: 37189538
DOI: 10.3390/diagnostics13081437