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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 -
Bioengineering (Basel, Switzerland) Mar 2020The atrioventricular heart valves (AHVs) are responsible for directing unidirectional blood flow through the heart by properly opening and closing the valve leaflets,... (Review)
Review
The atrioventricular heart valves (AHVs) are responsible for directing unidirectional blood flow through the heart by properly opening and closing the valve leaflets, which are supported in their function by the chordae tendineae and the papillary muscles. Specifically, the chordae tendineae are critical to distributing forces during systolic closure from the leaflets to the papillary muscles, preventing leaflet prolapse and consequent regurgitation. Current therapies for chordae failure have issues of disease recurrence or suboptimal treatment outcomes. To improve those therapies, researchers have sought to better understand the mechanics and microstructure of the chordae tendineae of the AHVs. The intricate structures of the chordae tendineae have become of increasing interest in recent literature, and there are several key findings that have not been comprehensively summarized in one review. Therefore, in this review paper, we will provide a summary of the current state of biomechanical and microstructural characterizations of the chordae tendineae, and also discuss perspectives for future studies that will aid in a better understanding of the tissue mechanics-microstructure linking of the AHVs' chordae tendineae, and thereby improve the therapeutics for heart valve diseases caused by chordae failures.
PubMed: 32178262
DOI: 10.3390/bioengineering7010025 -
Structural Heart : the Journal of the... Aug 2022Reshaping the dilated left ventricle using a surgically implanted papillary muscle sling has been shown to provide long-term improvement in cardiac function compared to...
BACKGROUND
Reshaping the dilated left ventricle using a surgically implanted papillary muscle sling has been shown to provide long-term improvement in cardiac function compared to annuloplasty alone in patients with systolic heart failure. A papillary muscle sling which can be implanted via a transcatheter approach has the potential to make this treatment more widely available to patients.
METHODS
The Vsling transcatheter papillary muscle sling device was evaluated in a chronic animal model (sacrificed at 30 and 90 days), in a simulator, and in a human cadaver.
RESULTS
The Vsling device was successfully implanted in 10 pigs, 6 simulator procedures, and 1 human cadaver. Procedure complexity and device usability were rated as reasonable or better by 6 interventional cardiologists. Gross and histological analysis in chronic pigs through 90 days demonstrated near-complete endothelial coverage with mild inflammation and small hematoma formation but without adverse tissue reactions, thrombi, or embolization.
CONCLUSIONS
Preliminary feasibility and safety of the Vsling implant and implantation procedure have been demonstrated. Human trials are planned to begin in the summer of 2022.
PubMed: 37288331
DOI: 10.1016/j.shj.2022.100075 -
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 -
Autopsy & Case Reports May 2020
PubMed: 33344286
DOI: 10.4322/acr.2020.169 -
Journal of Veterinary Diagnostic... Nov 2022A 7-y-old, captive, intact female meerkat () was presented with lethargy, decreased appetite, dyspnea, and distended abdomen. At autopsy, the right atrium was markedly...
A 7-y-old, captive, intact female meerkat () was presented with lethargy, decreased appetite, dyspnea, and distended abdomen. At autopsy, the right atrium was markedly dilated, and the right atrioventricular valve (RAV) was dysplastic with shortened or absent chordae tendineae and direct attachment of the valve to the papillary muscles, which, in turn, were fused and abnormally positioned. The right ventricle was considered to be hypertrophied. Also present were hydrothorax, ascites, atelectasis, and hepatic congestion. A diagnosis of RAV dysplasia was made. Histologic findings included hypertrophy of cardiomyocytes and marked centrilobular hepatic congestion and hemorrhage, which were consistent with right-sided heart failure.
Topics: Female; Animals; Chordae Tendineae; Tricuspid Valve; Heart Failure; Autopsy
PubMed: 36184940
DOI: 10.1177/10406387221128208 -
Cardiovascular Diabetology Jan 2023Type 2 Diabetes mellitus (T2DM) is a major risk factor for cardiovascular disease and associated with poor outcome after myocardial infarction (MI). In T2DM, cardiac...
BACKGROUND
Type 2 Diabetes mellitus (T2DM) is a major risk factor for cardiovascular disease and associated with poor outcome after myocardial infarction (MI). In T2DM, cardiac metabolic flexibility, i.e. the switch between carbohydrates and lipids as energy source, is disturbed. The RabGTPase-activating protein TBC1D4 represents a crucial regulator of insulin-stimulated glucose uptake in skeletal muscle by controlling glucose transporter GLUT4 translocation. A human loss-of-function mutation in TBC1D4 is associated with impaired glycemic control and elevated T2DM risk. The study's aim was to investigate TBC1D4 function in cardiac substrate metabolism and adaptation to MI.
METHODS
Cardiac glucose metabolism of male Tbc1d4-deficient (D4KO) and wild type (WT) mice was characterized using in vivo [F]-FDG PET imaging after glucose injection and ex vivo basal/insulin-stimulated [H]-2-deoxyglucose uptake in left ventricular (LV) papillary muscle. Mice were subjected to cardiac ischemia/reperfusion (I/R). Heart structure and function were analyzed until 3 weeks post-MI using echocardiography, morphometric and ultrastructural analysis of heart sections, complemented by whole heart transcriptome and protein measurements.
RESULTS
Tbc1d4-knockout abolished insulin-stimulated glucose uptake in ex vivo LV papillary muscle and in vivo cardiac glucose uptake after glucose injection, accompanied by a marked reduction of GLUT4. Basal cardiac glucose uptake and GLUT1 abundance were not changed compared to WT controls. D4KO mice showed mild impairments in glycemia but normal cardiac function. However, after I/R D4KO mice showed progressively increased LV endsystolic volume and substantially increased infarction area compared to WT controls. Cardiac transcriptome analysis revealed upregulation of the unfolded protein response via ATF4/eIF2α in D4KO mice at baseline. Transmission electron microscopy revealed largely increased extracellular matrix (ECM) area, in line with decreased cardiac expression of matrix metalloproteinases of D4KO mice.
CONCLUSIONS
TBC1D4 is essential for insulin-stimulated cardiac glucose uptake and metabolic flexibility. Tbc1d4-deficiency results in elevated cardiac endoplasmic reticulum (ER)-stress response, increased deposition of ECM and aggravated cardiac damage following MI. Hence, impaired TBC1D4 signaling contributes to poor outcome after MI.
Topics: Male; Mice; Humans; Animals; GTPase-Activating Proteins; Diabetes Mellitus, Type 2; Glucose; Insulin; Muscle, Skeletal; Myocardial Infarction; Reperfusion; Glucose Transporter Type 4
PubMed: 36707786
DOI: 10.1186/s12933-023-01746-2 -
Circulation Journal : Official Journal... Jul 2022
Topics: Abscess; Heart Rupture, Post-Infarction; Humans; Mitral Valve Insufficiency; Papillary Muscles
PubMed: 35228470
DOI: 10.1253/circj.CJ-22-0038 -
JTCVS Techniques Dec 2021
PubMed: 34977710
DOI: 10.1016/j.xjtc.2021.09.019