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Journal of the Mechanical Behavior of... Nov 2020The mitral valve (MV) apparatus is a complex mechanical structure including annulus, valve leaflets, papillary muscles (PMs) and connected chordae tendineae. Chordae...
The mitral valve (MV) apparatus is a complex mechanical structure including annulus, valve leaflets, papillary muscles (PMs) and connected chordae tendineae. Chordae anchor to the papillary muscles to help the valve open and close properly during one cardiac cycle. It is of paramount importance to understand the functional, mechanical, and microstructural properties of mitral valve chordae and connecting PMs. In particular, little is known about the biomechanical properties of the anterior and posterior papillary muscle and corresponding chords. In this work, we performed uniaxial and biaxial tensile tests on the anterolateral (APM) and posteromedial papillary muscle (PPM), and their respective corresponding chordae tendineae, chordae and chordae, in porcine hearts. Histology was carried out to link the microstructure and macro-mechanical behavior of the chordae and PMs. Our results demonstrate that chordae are less in number, but significantly longer and stiffer than chordae. These different biomechanical properties may be partially explained by the higher collagen core ratio and larger collagen fibril density of chordae No significant mechanical or microstructural differences were observed along the circumferential and longitudinal directions of APM and PPM samples. Data measured on chordae and PMs were further fitted with the Ogden and reduced Holzapfel - Ogden strain energy functions, respectively. This study presents the first comparative anatomical, mechanical, and structural dataset of porcine mitral valve chordae and related PMs. Results indicate that a PM based classification of chordae will need to be considered in the analysis of the MV function or planning a surgical treatment, which will also help developing more precise computational models of MV.
Topics: Animals; Chordae Tendineae; Collagen; Mitral Valve; Mitral Valve Insufficiency; Papillary Muscles; Swine
PubMed: 32835989
DOI: 10.1016/j.jmbbm.2020.104011 -
JACC. Cardiovascular Imaging Sep 2019This study sought to define interpapillary muscle dyssynchrony as a major contributing factor in functional mitral regurgitation (FMR) and prove the reversibility of FMR... (Observational Study)
Observational Study
OBJECTIVES
This study sought to define interpapillary muscle dyssynchrony as a major contributing factor in functional mitral regurgitation (FMR) and prove the reversibility of FMR by interpapillary muscle resynchronization.
BACKGROUND
Mechanistic features of FMR include papillary muscle displacement due to left ventricular remodeling. Intraventricular conduction delay might further augment this condition by introducing interpapillary muscle dyssynchrony.
METHODS
We enrolled 269 chronic heart failure with reduced ejection fraction patients with conduction delay and comprehensively assessed dyssynchrony by complementary echocardiographic techniques covering the entire spectrum of dyssynchrony.
RESULTS
Patients with severe FMR had markedly increased interpapillary longitudinal dyssynchrony (160 ms [interquartile range (IQR): 120 to 200 ms]) compared with those with moderate (70 ms [IQR: 40 to 110 ms]), no, or mild FMR (60 ms [IQR: 30 to 100 ms]; p < 0.001). Increased interpapillary muscle dyssynchrony was correlated with regurgitant volume (r = 0.50; p < 0.001) and vena contracta width (r = 0.49; p < 0.001). Restoration of longitudinal papillary muscle synchronicity by cardiac resynchronization therapy was correlated with FMR regression, as reflected by the reduction in regurgitant volume (r = 0.46; p < 0.001) and vena contracta width (r = 0.58; p < 0.001). Conversely, the improvement of FMR was associated with improved interpapillary radial (p = 0.006) and longitudinal (p < 0.001) dyssynchrony. The improvement of dyssynchrony-mediated FMR signified a better prognosis compared with no improvement in FMR during the 8-year follow-up period even after comprehensive adjustment by a bootstrap-selected confounder model (adjusted hazard ratio: 0.41; 95% confidence interval: 0.18 to 0.91; p = 0.028). The results remained virtually unchanged after adjustment for left bundle branch block.
CONCLUSIONS
Intraventricular dyssynchrony introduces unequal contraction by papillary muscle bearing walls, which has an adverse effect on FMR. Cardiac resynchronization therapy can effectively restore interpapillary balance and thus create a less tented leaflet configuration, resulting in a clinically meaningful reduction of FMR. The restoration of papillary muscle synchronicity in dyssynchrony-mediated FMR translates into a significantly better prognosis.
Topics: Aged; Cardiac Resynchronization Therapy; Chronic Disease; Female; Heart Failure; Humans; Male; Middle Aged; Mitral Valve; Mitral Valve Insufficiency; Myocardial Contraction; Papillary Muscles; Recovery of Function; Stroke Volume; Treatment Outcome; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Remodeling
PubMed: 30121264
DOI: 10.1016/j.jcmg.2018.06.013 -
Medicine Nov 2023Deciding whether to include or exclude the papillary muscles and trabeculae to blood pool is essential, because quantifications of left ventricular (LV) functional...
Deciding whether to include or exclude the papillary muscles and trabeculae to blood pool is essential, because quantifications of left ventricular (LV) functional parameters and myocardial mass are significantly affected. As a result, such inclusion or exclusion might produce different indices for diagnosis and therapy. Using cardiac computed tomography (CT), we obtained standard values of the portion of papillary muscle and trabeculae in normal adults, and to find out how the inclusion or exclusion of papillary muscle and trabeculae affect LV functional parameters depending on the patient group. Excluding the papillary muscles from the LV mass results in easier automated contour detection using CT. The percentage portions of papillary muscle and trabeculae to LV end-diastolic volume (EDV) and LV mass (LVM) were 11.9 ± 5.6% and 20.2 ± 4.3%, respectively, significantly affecting disease diagnosis. Imaging should be consistent at follow-up and include or exclude the papillary muscles and trabeculae to avoid introducing significant differences between measurements.
Topics: Adult; Humans; Papillary Muscles; Ventricular Function, Left; Cross-Sectional Studies; Heart Ventricles; Tomography, X-Ray Computed; Stroke Volume; Reproducibility of Results
PubMed: 37986395
DOI: 10.1097/MD.0000000000036106 -
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 -
Contractility detection of isolated mouse papillary muscle using myotronic Myostation-Intact device.Animal Models and Experimental Medicine Oct 2022To understand the relationship between myocardial contractility and external stimuli, detecting ex vivo myocardial contractility is necessary.
BACKGROUND
To understand the relationship between myocardial contractility and external stimuli, detecting ex vivo myocardial contractility is necessary.
METHODS
We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation-Intact system under different frequencies, voltages, and calcium concentrations.
RESULTS
The results indicated that the basal contractility of the papillary muscle was 0.27 ± 0.03 mN at 10 V, 500-ms pulse duration, and 1 Hz. From 0.1 to 1.0 Hz, contractility decreased with an increase in frequency (0.45 ± 0.11-0.10 ± 0.02 mN). The voltage-initiated muscle contractility varied from 3 to 6 V, and the contractility gradually increased as the voltage increased from 6 to 10 V (0.14 ± 0.02-0.28 ± 0.03 mN). Moreover, the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM (0.45 ± 0.17-1.11 ± 0.05 mN); however, the contractility stopped increasing even when the concentration was increased to 7.5 mM (1.02 ± 0.23 mN).
CONCLUSIONS
Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation-Intact users for isolated muscle contractility investigations.
Topics: Mice; Animals; Papillary Muscles; Myocardial Contraction
PubMed: 36168142
DOI: 10.1002/ame2.12272 -
JACC. Clinical Electrophysiology Oct 2020
Topics: Humans; Catheter Ablation; Electrophysiology; Papillary Muscles; Ventricular Premature Complexes
PubMed: 33121668
DOI: 10.1016/j.jacep.2020.08.005 -
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 -
Journal of the American College of... Aug 2018
Topics: Fibrosis; Heart Ventricles; Humans; Mitral Valve Insufficiency; Mitral Valve Prolapse; Papillary Muscles; Prolapse
PubMed: 30115221
DOI: 10.1016/j.jacc.2018.07.006 -
The Journal of Thoracic and... Jan 2022To categorize and assess the functional significance of anomalous papillary muscles in patients undergoing surgical management of obstructive hypertrophic cardiomyopathy.
OBJECTIVES
To categorize and assess the functional significance of anomalous papillary muscles in patients undergoing surgical management of obstructive hypertrophic cardiomyopathy.
METHODS
We reviewed the records of operations for obstructive hypertrophic cardiomyopathy and identified 73 patients with an anomalous papillary muscle. Anomalous papillary muscles inserting directly into the body of the anterior mitral valve leaflet were classified as type I, those with both direct insertion into the body of the leaflet and attachment to the free edge of the anterior leaflet were categorized as type II, and anomalous papillary muscles inserting into the free edge of the anterior leaflet were grouped as type III. Additionally, we investigated detection rates by preoperative transthoracic echocardiography, intraoperative transesophageal echocardiography, and cardiac magnetic resonance imaging.
RESULTS
The mean age of patients was 51.9 ± 12.3 years, and 49.3% were male. The anomalous papillary muscle was classified as type I in 31.5% of patients, type II in 35.6%, and type III in 32.9%. Only type I and type II anomalous papillary muscles contributed to left ventricular outflow tract obstruction. The anomalous papillary muscle was detected on preoperative transthoracic echocardiography in 11% of patients and by intraoperative transesophageal echocardiography in 27.4% of patients. No anomalous papillary muscles were identified on cardiac magnetic resonance imaging. All patients underwent septal myectomy with or without (n = 34) associated excision of the anomalous papillary muscle. Excision of the papillary muscles was more common in patients with type I and II (76.4% and 80.8%, respectively) when compared with type III (4.2%). Ten patients underwent mitral valve repair, and 1 patient had mitral valve replacement.
CONCLUSIONS
Papillary muscle abnormalities are important findings in patients with obstructive hypertrophic cardiomyopathy but are not identified preoperatively in the majority of patients. Recognition of anomalous papillary muscles intraoperatively and understanding of the morphologic subtypes are critical to adequate gradient relief and preservation of mitral valve function. The optimum approach involves a transaortic extended septal myectomy associated with the resection of the anomalous papillary muscles in patients with type I and II anatomy.
Topics: Cardiac Surgical Procedures; Cardiomyopathy, Hypertrophic; Echocardiography, Transesophageal; Female; Heart Septum; Humans; Intraoperative Complications; Magnetic Resonance Imaging, Cine; Male; Middle Aged; Mitral Valve; Mitral Valve Annuloplasty; Outcome and Process Assessment, Health Care; Papillary Muscles; Postoperative Complications; Preoperative Care; United States
PubMed: 32414597
DOI: 10.1016/j.jtcvs.2020.04.007 -
The Journal of Thoracic and... May 2018To characterize morphologic variations in the papillary muscles and tendinous cords of the left ventricle and ventricular zones of the mitral valve leaflets.
OBJECTIVES
To characterize morphologic variations in the papillary muscles and tendinous cords of the left ventricle and ventricular zones of the mitral valve leaflets.
METHODS
A total of 100 autopsied human hearts from healthy donors with classical mitral valve type were investigated.
RESULTS
In 1 heart, only 1 group of papillary muscles was found, and in the remaining 99%, we could distinguish 2 groups of muscles: Superolateral (SLPM) and inferoseptal papillary muscle (ISPM) groups. The SLPM group had 1 papillary muscle (75.8%), 2 in 20.2%, and >3 in 4.0%. In the ISPM group, the muscle percentages were 38.4%, 36.4%, and 25.2%, respectively. The apex of at least 1 papillary muscle was situated higher than the plane of the opened anterior leaflet (AML) in 47.5% and 50.5% for the SLPM and ISPM groups, respectively. The number of strut cords arising from the SLPM group was 0 (2.0%), 1 (50.5%), 2 (33.3%), 3 (12.1%), and 4 (2.0%), and from the ISPM group was 0 (6.1%), 1 (52.5%), 2 (35.4%), or 3 (6.1%). Cords to left ventricular outflow tract were present in 14 specimens. Muscular cords were found in eight hearts. In all hearts specimens AML had rough and clear zones. The classical zones (rough, clear, and basal) in the posterior mitral leaflet were observed in 38.4%.
CONCLUSIONS
There is a high variability in the papillary muscles and tendinous cords in the mitral valve complex. Proper nomenclature, simple classification, and the most common variants for papillary muscle groups and tendinous cords were presented.
Topics: Adult; Aged; Anatomic Landmarks; Autopsy; Chordae Tendineae; Dissection; Female; Humans; Male; Middle Aged; Mitral Valve; Papillary Muscles; Terminology as Topic
PubMed: 29397976
DOI: 10.1016/j.jtcvs.2017.12.061