Evaluation of mitral chordae tendineae length using four-dimensional computed

BACKGROUND Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation.Achieving precise measurements of artificial chordae tendineae length(CL)is an important factor in the procedure;however,no objective index currently exists to facilitate this measurement.Therefore,preoperative assessment of CL is critical for surgical planning and support.Four-dimensional x-ray micro-computed tomography(4D-CT)may be useful for accurate CL measurement considering that it allows for dynamic three-dimensional(3D)evaluation compared to that with transthoracic echocardiography,a conventional inspection method.AIM To investigate the behavior and length of mitral chordae tendineae during systole using 4D-CT.METHODS Eleven adults aged>70 years without mitral valve disease were evaluated.A 64-slice CT scanner was used to capture 20 phases in the cardiac cycle in electrocardiographic synchronization.The length of the primary chordae tendineae was measured from early systole to early diastole using the 3D image.The primary chordae tendineae originating from the anterior papillary muscle and attached to the A1-2 region and those from the posterior papillary muscle and attached to the A2-3 region were designated as cA and cP,respectively.The behavior and maximum lengths[cA(ma),cP(max)]were compared,and the correlation with body surface area(BSA)was evaluated.RESULTS In all cases,the mitral anterior leaflet chordae tendineae could be measured.In most cases,the cA and cP chordae tendineae could be measured visually.The mean cA(max)and cP(max)were 20.2 mm±1.95 mm and 23.5 mm±4.06 mm,respectively.cP(max)was significantly longer.The correlation coefficients(r)with BSA were 0.60 and 0.78 for cA(max)and cP(max),respectively.Both cA and cP exhibited constant variation in CL during systole,with a maximum 1.16-fold increase in cA and a 1.23-fold increase in cP from early to mid-systole.For cP,CL reached a plateau at 15%and remained elongated until end-systole,whereas for cA,after peaking at 15%,CL shortened slightly and then moved toward its peak again as end-systole approached.CONCLUSION The study suggests that 4D-CT is a valuable tool for accurate measurement of both the length and behavior of chordae tendineae within the anterior leaflet of the mitral valve.

Lead helix winding tricuspid chordae tendineae: A case report

BACKGROUND As left bundle branch pacing(LBBP)is more like physiological pacing,LBBP has emerged as a novel pacing strategy that uses the native conduction system to improve ventricular synchronization with stable pacing parameters.LBBP has been revealed associated with a significantly reduced risk of new-onset atrial fibrillation and heart failure compared with conventional permanent pacemaker implantation.CASE SUMMARY A 64-year-old man was admitted with a 24-h history of chest distress and shortness of breath,which continued unabated.The patient had no symptoms of chest pain,dizziness,syncope,nausea nor vomiting.There were no abnormalities found in routine examinations after admission.Twelve-lead electrocardiogram presented a result of 2:1 atrioventricular block.Coronary angiography was performed the next day and no abnormality was found.Finally,the patient agreed to received LBBP and signed the informed consent.During the process of withdrawing the Medtronic Model 3830 lead into sheath,we found the lead helix was wrapped around the chordae tendineae of the septal valve of tricuspid.Attempts to rotate the 3830 lead failed to release the lead helix from the chordae tendineae,and ultimately we used radiofrequency ablation to ablate the wrapped chordae tendineae.CONCLUSION Radiofrequency ablation effectively solved this problem without complications.It is an effective and reliable method to resolve lead winding chordae.

Safety of an improved patent ductus arteriosus occluder for transcatheter closure of perimembranous ventricular septal defects with abnormally attached tricuspid chordae tendineae

BACKGROUND The off-label use of various devices has been reported for the transcatheter closure of perimembranous ventricular septal defects(PmVSD) because of serious complications, such as heart block and tricuspid regurgitation(TR),associated with conventional ventricular septal defect devices. However, whether certain defects such as PmVSD with abnormally attached tricuspid are fit for interventional treatment is still disputable.AIM To explore the feasibility and safety of transcatheter closure of PmVSD with abnormally attached tricuspid chordae tendineae using an improved patent ductus arteriosus(PDA) occluder.METHODS We retrospectively analyzed 20 patients diagnosed with PmVSD with abnormally attached tricuspid chordae tendineae who underwent interventional treatment using an improved PDA occluder at our center from January 2012 to January 2016. Baseline characteristics and procedural and follow-up data were analyzed.RESULTS All 20 patients achieved procedure success. No heart block occurred during the operation. One patient had a transient complete right bundle branch block within48 h post-procedure and reverted to normal rhythm after intravenous injections of dexamethasone for 3 d. For all 20 patients, no residual shunt was observed by transthoracic echocardiography post-procedure. During the average follow-up period of 2.4 years, no severe TR was observed.CONCLUSION Using of the improved PDA occluder for the transcatheter closure of PmVSD with abnormally attached tricuspid chordae tendineae is a safe and promising treatment option. However, long-term follow-up in a large group of patients is still warranted.

Application of real-time 3d echocardiography in mitral valve repair for replacement of chordae tendineae

Objective To investigate the surgical technique and outcomes of replacement of chordae tendineae in mitral valve repair,and evaluate the value of real-time three-di-mensional transesophageal echocardiography in the perioperative period. Methods Thirty-one patients with mitral valve prolapse underwent mitral valve repair using chordae tendineae replacement concomitant with implantation

Structural and biomechanical characterizations of acellular porcine mitral valve scaffolds:anterior leaflets,posterior leaflets,and chordae tendineae

Mitral valve(MV)tissue engineering is still in its early stage,and one major challenge in MV tissue engineering is to identify appropriate scaffold materials.With the potential of acellular MV scaffolds being demonstrated recently,it is important to have a full understanding of the biomechanics of the native MV components and their acellular scaffolds.In this study,we have successfully characterized the structural and mechanical properties of porcine MV components,including anterior leaflet(AL),posterior leaflet(PL),strut chordae,and basal chordae,before and after decellularization.Quantitative DNA assay showed more than 90%reduction in DNA content,and Griffonia simplicifolia(GS)lectin immunohistochemistry confirmed the complete lack of porcine𝛼-Gal antigen in the acellular MV components.In the acellular AL and PL,the atrialis,spongiosa,and fibrosa trilayered structure,along with its ECM constitutes,i.e.,collagen fibers,elastin fibers,and portion of GAGs,were preserved.Never-theless,the ECM of both AL and PL experienced a certain degree of disruption,exhibiting a less dense,porous ECM morphology.The overall anatomical morphology of the strut and basal chordae were also maintained af-ter decellularization,with longitudinal morphology experiencing minimum disruption,but the cross-sectional morphology exhibiting evenly-distributed porous structure.In the acellular AL and PL,the nonlinear anisotropic biaxial mechanical behavior was overall preserved;however,uniaxial tensile tests showed that the removal of cellular content and the disruption of structural ECM did result in small decreases in maximum tensile modulus,tissue extensibility,failure stress,and failure strain for both MV leaflets and chordae.

Left ventricular false tendons and electrocardiogram repolarization abnormalities in healthy young subjects

AIM To describe echocardiographically left ventricular false tendon characteristics and the correlation with ventricular repolarization abnormalities in young athletes.METHODS Three hundred and sixteen healthy young athletes from different sport disciplines were evaluated from 2009 to 2011 during routine screening for agonistic sports eligibility. All subjects, as part of standard preparticipation screening medical evaluation, underwent a basal and post step test 12-lead electrocardiogram(ECG). The athletes with abnormal T-wave flattening and/or inversion were considered for an echocardiogram evaluation and an incremental maximal exercise test on a cycle ergometer. Arterial blood pressure and heart rate, during and after exercise, were also measured.RESULTS Twenty-one of the 316 subjects(6.9%) showed false tendons in the left ventricle. The majority of false tendons(52.38%) were localized between the middle segments of the inferior septum and the lateral wall, 19.06% between the distal segments of the septum and the lateral wall, in 5 subjects between the middle segments of the anterior and inferior walls, and in one subject between the middle segments of the anterior septum and the posterior wall. ECG abnormalities, represented by alterations of ventricular repolarization, were found in 11 subjects(52.38%), 90% of these anomalies were T wave abnormalities from V1 to V3. These anomalies disappeared with an increasing heart rate following the three minute step test as well as during the execution of the maximal exercise.CONCLUSION Left ventricular false tendons are frequently localized between the middle segments of the inferior septum and the lateral wall and are statistically associated with ventricular repolarization abnormalities.

An Investigation of Regional Variations in the Biaxial Mechanical Properties of Porcine Mitral Valve

Objective Mitral valve(MV)plays an importance role in regulating blood flow from left atrium to left ventricle and preventing backflow to left atrium.Mitral Valve consist of four important parts;anterior leaflet,posterior leaflet,chordae tendineae,and papillary muscles,which all work in harmony.The material properties alteration on the leaflet causes MV malfunction,and leading to valve diseases such as regurgitation and stenosis.The alteration may be caused by several factors such as calcification,genetic disorders,and infection,which usually have an influence to the mechanical properties,and thus affecting the mechanical behavior of MV.In consequence,some of the patients need MV replacement or repair to restore the normal function of MV.The important point for succeeding such a medical treatment depends on the technique,design,and material used in the treatment shall help rebuild the normal mechanical environment and behavior of MV.Therefore,the mechanical and materials characteristics of MV become a magnetism to explore.In this study,we present an integrated experimental and mathematical constitutive study base in collagen distribution aiming at the mechanical property differences in various region on MV.Methods and materials Both the size and composition of porcine valves are similar to human’s,so the porcine heart valve is often being used in experimental research.Mitral valve was isolated from fresh eight porcine hearts(250-500 gr),and perfused in PBS solution to maintain moist.Anterior and posterior leaflets were separated and dissected into 4 part(two 8~*8 mm rough zone and two clear zone samples)and 2 part(8~*8 mm belly and edge of the clear zone)respectively.Tracking markers(glass bean)were stickled on specimen with superglue(cyanoacrylate adhesive).Then,the specimen was mounted onto biaxial tester machine(CeIIScale,Biotester),and the tests are run by force control.During mechanical test,the specimen is immersed into PBS solution in physiological temperature(37℃).Every test procedure contains 8 preconditioning cycles and 8 loading cycles.The mechanical behavior was determined from the relationship between first Piola-Kirchoff stress and stretch.Constitutive model was reconstructed and material parameters were fitted from biaxial tensile result.Histological analyses were performed in the specimen before and after test.First,a piece of the specimen was cut and immersed in fixation solution(4%paraformaldehyde),then it was dehydrated in graded alcohol solution,and next embedding in paraffin wax block.Paraffin block was then cut and stained with VVG and Picro-sirius red.The collagen fibril orientation was observed from those histological results.Results The experimental results of the clear zone of MV’s first Piola-Kirchhoff stress and stretch curve are similar to those of the recent study from others,while result of the rough zone shows a different trend.This can be explained by differences in collagen distribution between clear zone and rough zone of MV.Our result thus allows for a refinement of computational models for more accurately predicting MV condition,where tissue heterogeneity plays an important role in the MV function.