Efficacy of chordal cutting to relieve chronic persistent ischemic mitral regurgitation

Long-term outcomes of left ventricular posterior wall plication for ischemic mitral regurgitation

Purpose

To evaluate the early and long-term outcomes of left ventricular posterior wall plication for ischemic mitral regurgitation.

Methods

Patients with ischemic mitral regurgitation who underwent left ventricular posterior wall plication via right-sided left atriotomy at our institution between 2010 and 2020 were retrospectively reviewed. Cases with normal cardiac function, left ventricular end-systolic diameter < 50 mm, and left ventriculotomy approach were excluded.

Results

The mean follow-up period was 5.3 years [standard deviation (SD) = 3.5], with a maximum of 10 years. Among the 21 patients enrolled, 9 had New York Heart Association (NYHA) class ≥ III. Three patients required preoperative inotrope support, while two preoperative ventilator support. The mean left ventricular ejection fraction was 31.4% (SD: 8.6), and 16 patients had mitral regurgitation grade ≥ III. All patients underwent coronary artery bypass grafting and mitral annuloplasty. Concomitant surgeries included 11 chordae cutting and 3 tricuspid annuloplasties. One in-hospital death occurred due to sepsis. At the follow-up, echocardiographic data showed significant improvement in cardiac dilation and function and good control of mitral regurgitation. The serum brain natriuretic peptide level was significantly reduced, and 85% of patients improved to NYHA class I. Four deaths occurred later due to sudden, unknown causes. The 5- and 8-year survival rates were 60.2% and 46.8%, respectively, and the 5- and 8-year hospitalization rates due to heart failure were 14.9% and 21.3%, respectively.

Conclusion

The long-term outcomes of left ventricular posterior wall plication were satisfactory for controlling heart failure and improving survival rate and patient prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-023-01527-2.

Utilization of Engineering Advances for Detailed Biomechanical Characterization of the Mitral-Ventricular Relationship to Optimize Repair Strategies: A Comprehensive Review

The geometrical details and biomechanical relationships of the mitral valve-left ventricular apparatus are very complex and have posed as an area of research interest for decades. These characteristics play a major role in identifying and perfecting the optimal approaches to treat diseases of this system when the restoration of biomechanical and mechano-biological conditions becomes the main target. Over the years, engineering approaches have helped to revolutionize the field in this regard. Furthermore, advanced modelling modalities have contributed greatly to the development of novel devices and less invasive strategies. This article provides an overview and narrative of the evolution of mitral valve therapy with special focus on two diseases frequently encountered by cardiac surgeons and interventional cardiologists: ischemic and degenerative mitral regurgitation.

Exploring the Operative Strategy for Secondary Mitral Regurgitation: A Systematic Review

Background

Mitral valve disease surgery is an evolving field with multiple possible interventions. There is an increasing body of evidence regarding the optimal strategy in secondary mitral regurgitation where the pathology lies within the ventricle. We conducted a systematic review to identify the benefits and limitations of each surgical option.

Methods

A systematic review of the literature was performed to identify pertinent randomized controlled trials (RCTs), propensity-matched observational series, and meta-analyses which were considered initially and followed by unmatched observational series using the MEDLINE, Ovid EMBASE, and Cochrane Library.

Results

We identified 6 different strategies for treating secondary mitral valve regurgitation: mitral valve replacement, restrictive mitral annuloplasty, surgical revascularization (with and without mitral annuloplasty), subvalvular procedures (papillary muscle approximation, papillary muscle relocation, ring and string procedure), and procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement) alongside transcatheter heart valve therapy. We also highlighted the role of left ventricular assist devices in the management of this condition. The benefits and limitations of each intervention are highlighted.

Conclusion

There is currently no unanimous and shared strategy for the optimal treatment of patients with secondary IMR. The management of patients with secondary mitral regurgitation must be entrusted to a multidisciplinary Heart Team to ensure ideal intervention and patient matching for the best outcomes.

Anatomy of Mitral Valve Complex as Revealed by Non-Invasive Imaging: Pathological, Surgical and Interventional Implications

Knowledge of mitral valve (MV) anatomy has been accrued from anatomic specimens derived by cadavers, or from direct inspection during open heart surgery. However, today two-dimensional and three-dimensional transthoracic (2D/3D TTE) and transesophageal echocardiography (2D/3D TEE), computed tomography (CT) and cardiac magnetic resonance (CMR) provide images of the beating heart of unprecedented quality in both two and three-dimensional format. Indeed, over the last few years these non-invasive imaging techniques have been used for describing dynamic cardiac anatomy. Differently from the “dead” anatomy of anatomic specimens and the “static” anatomy observed during surgery, they have the unique ability of showing “dynamic” images from beating hearts. The “dynamic” anatomy gives us a better awareness, as any single anatomic arrangement corresponds perfectly to a specific function. Understanding normal anatomical aspects of MV apparatus is of a paramount importance for a correct interpretation of the wide spectrum of patho-morphological MV diseases. This review illustrates the anatomy of MV as revealed by non-invasive imaging describing physiological, pathological, surgical and interventional implications related to specific anatomical features of the MV complex.

Clinical manifestations, diagnosis, and treatment of ischemic mitral regurgitation: a review

Ischemic mitral regurgitation (IMR) is a frequent complication after acute myocardial infarction (AMI) associated with a worse prognosis. The pathophysiological mechanisms of IMR are not fully understood, but it is known to be a complex process in which ventricular remodelling is the main causal factor. The various imaging techniques in cardiology and echocardiography fundamentally have contributed significantly to clarify the mechanisms that cause and progressively aggravate IMR. At present, different therapeutic options, the most important of which are cardio-surgical, address this problem. Nowadays the improvement in cardiac surgery and transcatheter therapies, have shown a therapeutic advance in IMR management. IMR is a predictor of poor prognosis in patients with heart failure and depressed left ventricular (LV) systolic function. However, it remains controversial whether mitral regurgitation (MR) in these patients is a consequence of dilation and dysfunction of the LV, or whether it contributes to worsening the prognosis of the ventricular dysfunction. Given that echocardiography has a fundamental reference role in the identification, graduation of severity and evaluation of the therapeutics used in the treatment of MR, we are going to focus on it over the rest of the imaging techniques. In contrast to primary MR the benefits of mitral surgery in patients with secondary MR are uncertain. Therefore, we will comment fundamentally on the role of mitral surgery in patients with IMR, with an update of the different surgical interventions available, without forgetting to mention the other therapeutic options currently available.

Ischemic mitral regurgitation

Ischemic mitral regurgitation (IMR) is a frequent complication of left ventricular (LV) global or regional pathological remodeling due to chronic coronary artery disease. It is not a valve disease but represents the valvular consequences of increased tethering forces and reduced closing forces. IMR is defined as mitral regurgitation caused by chronic changes of LV structure and function due to ischemic heart disease and it worsens the prognosis. In this review, we discuss on etiology, pathophysiology, and mechanisms of IMR, its classification, evaluation, and therapeutic corrective methods of IMR.

A Swine Model of Percutaneous Intracoronary Ethanol Induced Acute Myocardial Infarction and Ischemic Mitral Regurgitation

Ischemic mitral regurgitation (IMR) is a frequent complication after a myocardial infarction (MI), which doubles mortality. Transcatheter mitral repairs are emerging as alternative treatment options to open heart surgery for IMR, but animal models to test them are lacking. We report a percutaneous swine model of IMR. Seventeen swine were randomized to (group 1, n = 12) MI causing IMR, and (group 2, n = 5) controls. In group 1, MI was induced via percutaneous ethanol injection into the obtuse marginal branches of the left circumflex artery, resulting in ST elevating myocardial infarction. Nine animals were survived to 8-10 weeks with weekly echocardiograms and three swine were survived to 16-20 weeks with MRI at termination. In group 1 animals, average IMR fraction at termination was 26.6 ± 2.3% in the echo group, and 24.51 ± 0.41% in the MRI group. None of the animals in group 2 had IMR. Left ventricular dysfunction and significant dilatation were evident in group 1 animals, compared to the controls. In conclusion, a reproducible model of IMR is reported for use in pre-clinical testing of new mitral technologies.

Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography

Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE.Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes).Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement.

Repair or replace for severe ischemic mitral regurgitation: prospective randomized multicenter data

Ischemic mitral regurgitation (IMR) is a subset of functional mitral regurgitation (MR) that has the potential to impact an increasing number of patients in the future. This is in the context of a worldwide population, which continues to live longer with improved survival after myocardial infarction. Substantial data have accumulated over the past few decades demonstrating the negative effects of IMR. Further, significant research has been done to define the optimal surgical approach and several studies have compared mitral repair versus replacement for patients with severe mitral regurgitation (SMR). Studies supporting performance of mitral repair cite superior operative morbidity and mortality rates, while proponents of mitral replacement cite improved long-term durability and correction of MR. Lack of clinically robust Level I randomized controlled trial data have curtailed attempts to better define appropriate surgical treatment allocation over the past few decades. Recently, however, the Cardiothoracic Surgical Trials Network (CTSN) conducted the first randomized controlled trial, funded by the National Heart, Lung, and Blood Institute, the National Institute for Neurological Diseases and Stroke and the Canadian Institute for Health Research, to compare the performance of mitral repair versus replacement for SMR. Herein, the present review describes the design, results and implications of the CTSN SMR trial and its efforts to identify the most efficacious surgical approach to SMR. This review also describes CTSN investigation to predict the recurrence of MR after mitral repair.

Mitral valve disease--morphology and mechanisms

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

Morphological study of chordae tendinae in human cadaveric hearts

Objectives:

The chordae tendinae (CT) are strong, fibrous connections between the valve leaflets and the papillary muscles. Dysfunction of the papillary muscles and chordae is frequent. Mitral valve replacement with preservation of CT and papillary muscles may preserve postoperative left ventricular function better than conventional mitral valve replacement in patients with chronic mitral regurgitation.

Methods:

The study was carried out on 116 human cadaveric hearts. The heart was opened through the atrioventricular valve to view the constituents of the complex. Origin, attachments, insertions, distribution, branching pattern and gross structure of CT were observed and studied in detail.

Results:

In the present study more than 21 terminologies of CT were defined by classifying it into six different types. Classification is done according to the origin, attachments, insertion, distribution, branching pattern and gross structure. Terminologies defined are as follows. Apical pillar chordae, Basal pillar chordae, True chordae, False chordae, Interpillar chordae, Pillar wall chordae, Cusp chordae, Cleft chordae, Commissural chordae, First order chordae, Second order chordae, Free zone chordae, Marginal chordae, Rough zone chordae, Straight chordae, Branched-fan shaped chordae, Spiral chordae, Irregular-web chordae, Tendinous chordae, Muscular chordae, Membranous chordae. Basal pillar chordae are found in 9.48%. Mean number of chordae taking origin from apical half of a single papillary muscle or single head of papillary muscle was 9.09 with the range of 3-18. Mean number of the marginal chordae attached to a single cusp was 22.63 ranging from 11 to 35. Strut chordae showed interesting insertion with broad aponeurosis in 38.79% and large muscular flaps in 13.79%. Chordae muscularis were found in 14% and membranous chordae were found in 6%.

Conclusions:

This knowledge may prove useful for cardiologists and cardiac surgeons.

Basic mechanisms of mitral regurgitation

Any structural or functional impairment of the mitral valve (MV) apparatus that exhausts MV tissue redundancy available for leaflet coaptation will result in mitral regurgitation (MR). The mechanism responsible for MV malcoaptation and MR can be dysfunction or structural change of the left ventricle, the papillary muscles, the chordae tendineae, the mitral annulus, and the MV leaflets. The rationale for MV treatment depends on the MR mechanism and therefore it is essential to identify and understand normal and abnormal MV and MV apparatus function.

Midterm outcomes of chordal cutting in combination with downsized ring annuloplasty for ischemic mitral regurgitation

PURPOSE

We describe midterm outcomes after division of secondary chords (chordal cutting) combined with downsized ring annuloplasty for ischemic mitral regurgitation (IMR).

METHODS

We compared the clinical outcomes in patients who underwent chordal cutting with downsized ring annuloplasty (CC-group, n = 15) and those who underwent conventional ring annuloplasty only (Conventional-group, n = 35) for IMR. Follow-up was complete in all patients. The median follow-up time was 4.1 years.

RESULTS

Thirty-day mortality was 0% in CC-group and 20% in Conventional-group. The overall survival rate at 5-year was 80.8% ± 12.6% in CC-group and 61.7% ± 8.4% in Conventional-group (Log-rank, p = 0.145). The freedom rate from valve-related events at 5 year was 84.6% ± 10.0% in CC-group and 65.3% ± 10.1% in Conventional-group (Log-rank, p = 0.213). Recurrence of severe mitral regurgitation was revealed in 3 patients of CC-group. Preoperative tenting height was the significant predictor of mitral regurgitation recurrence. In CC-group, the mean left ventricular ejection fraction was 38.0% ± 14.0%, which was similar to the preoperative value of 40.0% ± 13.2% (p = 0.349).

CONCLUSIONS

Chordal cutting with downsized ring annuloplasty for IMR is a simple method and provides satisfactory early outcomes. However, it carries with high recurrence of MR especially for patients with high tenting height.

Ischemic mitral regurgitation: pathophysiology, diagnosis and surgical treatment

Ischemic mitral valve regurgitation often complicates acute myocardial infarction and also represents a negative prognostic factor for long-term survival in patients undergoing surgical myocardial revascularization. While severe mitral regurgitation should always be corrected during a coronary artery bypass operation, the decision making is more difficult in patients with a mild-to-moderate degree of regurgitation. Recent studies and experimental protocols have elucidated the pathophysiological mechanisms leading to mitral regurgitation with great interest in annular modifications and subvalvular alterations. These data suggest that new and integrated surgical approaches that address annuloplasty ring sizing, ring type selection and tethering phenomenon (i.e., chordal cutting, 'edge-to-edge' technique and left-ventricular plasty techniques) are required for a safer and durable valve repair. Transthoracic and transesophageal echocardiography are useful in determining the etiology and the degree of mitral regurgitation, to assess mitral deformation and to measure indexes of global and regional left-ventricular remodeling. Stress echocardiography may unmask higher degrees of mitral regurgitation. More data are needed in order to confirm the promising and interesting preliminary experimental findings of magnetic resonance imaging in diagnosis and clinical evaluation of ischemic mitral regurgitation.

Efficient preloading of the ventricles by a properly timed atrial contraction underlies stroke work improvement in the acute response to cardiac resynchronization therapy

BACKGROUND

The acute response to cardiac resynchronization therapy (CRT) has been shown to be due to 3 mechanisms: resynchronization of ventricular contraction, efficient preloading of the ventricles by a properly timed atrial contraction, and mitral regurgitation reduction. However, the contribution of each of the 3 mechanisms to the acute response to CRT, specifically stroke work improvement, has not been quantified.

OBJECTIVE

To use a magnetic resonance image-based anatomically accurate 3-dimensional model of failing canine ventricular electromechanics to quantify the contribution of each of the 3 mechanisms to stroke work improvement and identify the predominant mechanisms.

METHODS

An MRI-based electromechanical model of the failing canine ventricles assembled previously by our group was further developed and modified. Three different protocols were used to dissect the contribution of each of the 3 mechanisms to stroke work improvement.

RESULTS

Resynchronization of ventricular contraction did not lead to a significant stroke work improvement. Efficient preloading of the ventricles by a properly timed atrial contraction was the predominant mechanism underlying stroke work improvement. Stroke work improvement peaked at an intermediate atrioventricular delay, as it allowed ventricular filling by atrial contraction to occur at a low diastolic left ventricular pressure but also provided adequate time for ventricular filling before ventricular contraction. Reduction of mitral regurgitation by CRT led to stroke work worsening instead of improvement.

CONCLUSION

Efficient preloading of the ventricles by a properly timed atrial contraction is responsible for a significant stroke work improvement in the acute CRT response.

Anatomy of the mitral valve apparatus: role of 2D and 3D echocardiography

The mitral valve apparatus is a complex 3-dimensional (3D) functional unit that is critical to unidirectional heart pump function. This review details the normal anatomy, histology, and function of the main mitral valve apparatus components: mitral annulus, mitral valve leaflets, chordae tendineae, and papillary muscles. Two-dimensional and 3D echocardiography is ideally suited to examine the mitral valve apparatus and has provided important insights into the mechanism of mitral valve disease. An overview of standardized echocardiography image acquisition and interpretation is provided. Understanding normal mitral valve apparatus function is essential to comprehend alterations in mitral valve disease and the rationale for repair strategies.

Comprehensive annular and subvalvular repair of chronic ischemic mitral regurgitation improves long-term results with the least ventricular remodeling

BACKGROUND

Undersized ring annuloplasty for ischemic mitral regurgitation (MR) is associated with variable results and >30% MR recurrence. We tested whether subvalvular repair by severing second-order mitral chordae can improve annuloplasty by reducing papillary muscle tethering.

METHODS AND RESULTS

Posterolateral myocardial infarction known to produce chronic remodeling and MR was created in 28 sheep. At 3 months, sheep were randomized to sham surgery versus isolated undersized annuloplasty versus isolated bileaflet chordal cutting versus the combined therapy (n=7 each). At baseline, chronic myocardial infarction (3 months), and euthanasia (6.6 months), we measured left ventricular (LV) volumes and ejection fraction, wall motion score index, MR regurgitation fraction and vena contracta, mitral annulus area, and posterior leaflet restriction angle (posterior leaflet to mitral annulus area) by 2-dimensional and 3-dimensional echocardiography. All groups were comparable at baseline and chronic myocardial infarction, with mild to moderate MR (MR vena contracta, 4.6±0.1 mm; MR regurgitation fraction, 24.2±2.9%) and mitral annulus dilatation (P<0.01). At euthanasia, MR progressed to moderate to severe in controls but decreased to trace with ring plus chordal cutting versus trace to mild with chordal cutting alone versus mild to moderate with ring alone (MR vena contracta, 5.9±1.1 mm in controls, 0.5±0.08 with both, 1.0±0.3 with chordal cutting alone, 2.0±0.4 with ring alone; P<0.01). In addition, LV end-systolic volume increased by 108% in controls versus 28% with ring plus chordal cutting, less than with each intervention alone (P<0.01). In multivariate analysis, LV end-systolic volume and mitral annulus area most strongly predicted MR (r(2)=0.82, P<0.01).

CONCLUSIONS

Comprehensive annular and subvalvular repair improves long-term reduction of both chronic ischemic MR and LV remodeling without decreasing global or segmental LV function at follow-up.

Effect of anterior strut chordal transection on the force distribution on the marginal chordae of the mitral valve

OBJECTIVES

Transection of the secondary chordae on the anterior leaflet of the mitral valve to relieve leaflet tethering and reduce regurgitation is an experimentally proven procedure to correct functional mitral regurgitation. In the present study, we sought to investigate whether transecting the secondary chordae would have an effect on the marginal chordal force on the same leaflet.

METHODS

Adult porcine mitral valves (n = 8) were studied in a pulsatile heart simulator, in which the papillary muscle positions can be precisely positioned. Miniature transducers were inserted into the anterior marginal chordae to measure the chordal forces. Each valve was studied under baseline conditions, 3 different tethering conditions (apical, apical-lateral, and apical-lateral-posterior), and after chordal cutting in the 3 tethering conditions. The temporal changes and peak and average marginal chordal forces under each condition are reported.

RESULTS

Apical tethering increased the marginal chordal force by an average of 96% but remained unchanged after chordal cutting. With apical-lateral tethering, the marginal chordal force increased by 210% from baseline and increased further to 350% of baseline after chordal cutting. After apical-lateral-posterior tethering, the marginal chordal force increased to 335% of baseline before transection and by 548% after transection.

CONCLUSIONS

The increase in the marginal chordal force after secondary chordal cutting depends on the location of the papillary muscles and the extent of leaflet tethering. Although chordal cutting might not alter the valve mechanics under minimal leaflet tethering, it significantly affects the mechanics when the leaflet tethering is more pronounced, which is typically seen in patients with functional mitral regurgitation.

Optimal surgical management of severe ischemic mitral regurgitation: to repair or to replace?

BACKGROUND

Ischemic mitral regurgitation, a complication of myocardial infarction and coronary artery disease more generally, is associated with a high mortality rate and is estimated to affect 2.8 million Americans. With 1-year mortality rates as high as 40%, recent practice guidelines of professional societies recommend repair or replacement, but there remains a lack of conclusive evidence supporting either intervention. The choice between therapeutic options is characterized by the trade-off between reduced operative morbidity and mortality with repair versus a better long-term correction of mitral insufficiency with replacement. The long-term benefits of repair versus replacement remain unknown, which has led to significant variation in surgical practice.

METHODS AND RESULTS

This article describes the design of a prospective randomized clinical trial to evaluate the safety and effectiveness of mitral valve repair and replacement in patients with severe ischemic mitral regurgitation. This trial is being conducted as part of the Cardiothoracic Surgical Trials Network. This article addresses challenges in selecting a feasible primary end point, characterizing the target population (including the degree of mitral regurgitation) and analytical challenges in this high mortality disease.

CONCLUSIONS

The article concludes by discussing the importance of information on functional status, survival, neurocognition, quality of life, and cardiac physiology in therapeutic decision making.

Relief of mitral leaflet tethering following chronic myocardial infarction by chordal cutting diminishes left ventricular remodeling

BACKGROUND

one of the key targets in treating mitral regurgitation (MR) is reducing the otherwise progressive left ventricular (LV) remodeling that exacerbates MR and conveys adverse prognosis. We have previously demonstrated that severing 2 second-order chordae to the anterior mitral leaflet relieves tethering and ischemic MR acutely. The purpose of this study was to test whether this technique reduces the progression of LV remodeling in the chronic ischemic MR setting.

METHODS AND RESULTS

a posterolateral MI was created in 18 sheep by obtuse marginal branch ligation. After chronic remodeling and MR development at 3 months, 6 sheep were randomized to sham surgery (control group) and 12 to second-order chordal cutting (6 each to anterior leaflet [AntL] and bileaflet [BiL] chordal cutting, techniques that are in clinical application). At baseline, chronic infarction (3 months), and follow-up at a mean of 6.6 months post-myocardial infarction (MI) (euthanasia), we measured LV end-diastolic (EDV) and end-systolic volume (ESV), ejection fraction, wall motion score index, and posterior leaflet (PL) restriction angle relative to the annulus by 2D and 3D echocardiography. All measurements were comparable among groups at baseline and chronic MI. At euthanasia, AntL and BiL chordal cutting limited the progressive remodeling seen in controls. LVESV increased relative to chronic MI by 109±8.7% in controls versus 30.5±6.1% with chordal cutting (P<0.01) (LVESV in controls, 82.5±2.6 mL; in AntL, 60.6±5.1 mL; in BiL, 61.8±4.1 mL). LVEDV increased by 63±2.0% in controls versus 26±5.5% and 22±3.4% with chordal cutting (P<0.01). LV ejection fraction and wall motion score index were not significantly different at follow-up among the chordal cutting and control groups. MR progressively increased to moderate in controls but decreased to trace-mild with AntL and BiL chordal cutting (MR vena contracta in controls, 5.9±1.1 mm; in AntL, 2.6±0.1 mm; in BiL, 1.7±0.1 mm; P<0.01). BiL chordal cutting provided greater PL mobility (decreased PL restriction angle to 54.2±5.0° versus 83±3.2° with AntL chordal cutting; P<0.01).

CONCLUSIONS

reduced leaflet tethering by chordal cutting in the chronic post-MI setting substantially decreases the progression of LV remodeling with sustained reduction of MR over a chronic follow-up. These benefits have the potential to improve clinical outcomes.

Design of a Catheter-Based Device for Performing Percutaneous Chordal-Cutting Procedures

This paper focuses on the design and implementation of a percutaneous catheter-based device to provide physicians with an externally controlled tool capable of manipulating and cutting specific chordae tendinae within the hear to alleviate problems associated with some forms of mitral valve regurgitationt. In the United States alone, approximately 500,000 people develop ischemic or functional MR per year, and the chordae tendinae cutting procedure and device are needed because many patients do not have the required level of health necessary to survive open-heart surgery. A deterministic design process was used to generate several design concepts and then evaluate and compare each concept based on a set of functional requirements. A final concept to be alpha prototyped was then chosen, further developed, and fabricated. Experiments showed that the design was capable of locating and grabbing a chord and that ultrasound imaging is a viable method for navigating the device inside of the human body. Once contact between the chord and an RF ablator tip was confirmed, the chord was successfully ablated.

Quantification of Mitral Apparatus Dynamics in Functional and Ischemic Mitral Regurgitation Using Real-time 3-Dimensional Echocardiography

Mitral regurgitation (MR) in dilated cardiomyopathy (DCM-MR) and MR in ischemic cardiomyopathy (ISC-MR) usually occurs as a result of mitral annulus (MA) dilatation and papillary muscle displacement secondary to global left ventricle remodelling. We propose a method to determine MA area and motion throughout the cardiac cycle and to define papillary muscle position in 3-dimensional space using real-time 3-dimensional echocardiography. Real-time 3-dimensional echocardiography was performed in 24 healthy individuals, and in 30 patients with DCM-MR (n = 15) or ISC-MR (n = 15). Significant intergroup differences were noted in MA surface area (control: 6.4 +/- 1.7 cm(2); DCM-MR: 11.1 +/- 2.6 cm(2); ISC-MR: 9.0 +/- 2.0 cm(2)) and in peak MA motion (control: 8.7 +/- 3.0 mm; DCM-MR: 3.4 +/- 1.7 mm; ISC-MR: 4.9 +/- 1.5 mm). In patients with DCM-MR, papillary muscle symmetry was preserved, whereas in patients with ISC-MR, papillary tethering lengths were unequal as a result of wall-motion abnormalities. Our methodology for dynamic volumetric measurements of the mitral apparatus allows better understanding of MR mechanisms.

Efficacy of chordal cutting in alleviating ischemic mitral regurgitation: insights from 3-dimensional echocardiography

Background

Ischemic mitral regurgitation often complicates severe ischemic heart disease and adversely affects the prognosis in these patients. There is wide variation in the clinical spectrum of ischemic mitral regurgitation due to varying location and chronicity of ischemia and anomalies in annular and ventricular remodeling. As a result, there is lack of consensus in treating these patients. Treatment has to be individualized for each patient. Most of the available surgical options do not consistently correct this condition in all the patients. Chordal cutting is one of the newer surgical approaches in which cutting a limited number of critically positioned basal chordae have found success by relieving the leaflet tethering and thereby improving the coaptation of leaflets. Three-dimensional echocardiography is a potentially valuable tool in identifying the specific pattern of tethering and thus the suitability of this procedure in a given clinical scenario.

Case Presentation

A 66-year-old man with cardiomyopathy and ischemic mitral regurgitation presented to us with the features of congestive heart failure. The three-dimensional echocardiography revealed severe mitral regurgitation associated with the tethering of the lateral (P1) and medial (P3) scallops of the posterior leaflet of the mitral valve due to secondary chordal attachments. The ejection fraction was only 15% with severe global systolic and diastolic dysfunction. Mitral regurgitation was successfully corrected with mitral annuloplasty and resection of the secondary chordae tethering the medial and lateral scallops of the posterior leaflet of the mitral valve.

Conclusion

Cutting the second order chordae along with mitral annuloplasty could be a novel method to remedy Ischemic mitral regurgitation by relieving the tethering of the valve leaflets. The preoperative three-dimensional echocardiography should be considered in all patients with Ischemic mitral regurgitation to assess the complex three-dimensional interactions between the mitral valve apparatus and the left ventricle. This aids in timely surgical planning.

Chordal Tethering: A Unique Cause of Structural Mitral Regurgitation in Dilated Cardiomyopathy

Mitral regurgitation in dilated cardiomyopathy is usually considered “functional,” and many such patients are treated medically. Surgery is often offered as a last resort in select patients who have failed medical therapy. We report a patient with dilated cardiomyopathy with ventricular tachycardia and ventricular dyssynchrony and “structural mitral regurgitation” due to chordal tethering, which was managed surgically using a minimally invasive approach.

Preoperative Posterior Leaflet Angle Accurately Predicts Outcome After Restrictive Mitral Valve Annuloplasty for Ischemic Mitral Regurgitation

Background— Ischemic mitral regurgitation (MR) often persists after restrictive mitral valve annuloplasty, in which case it is associated with worse clinical outcomes. The goal of the present study was to determine whether persistence of MR and/or clinical outcome could be predicted from preoperative analysis of mitral valve configuration.

Methods and Results— In 51 consecutive patients undergoing restrictive annuloplasty for ischemic MR, posterior leaflet (PL) angle, anterior leaflet angle, coaptation distance, and tenting area were quantified by echocardiography before surgery (6±3 days), and MR severity was assessed before and early after surgery (9±4 days). Postoperatively, persistence of mild to moderate MR (vena contracta >3 mm) was observed in 11 (22%) of the patients. The best predictor of postoperative persistence of MR was a PL angle ≥45 degrees (sensitivity 100%, specificity 97%, positive predictive value 92%, negative predictive value 100%). Patients with persistent MR had markedly lower 3-year event-free survival (26±20%) compared with those with nonpersistent MR (75±12%, P =0.01). Preoperative presence of a PL angle ≥45 degrees also was associated with a markedly lower 3-year event-free survival (22±17% versus 76±12%; P <0.001).

Conclusions— In patients undergoing restrictive annuloplasty for ischemic MR, persistence of MR and 3-year event-free survival can accurately be predicted by preoperative analysis of mitral valve configuration. Patients with a PL angle ≥45 degrees (ie, with high PL restriction) should thus be considered poor candidates for this procedure, and concomitant or alternative procedures should be contemplated.

Three-dimensional versus two-dimensional transesophageal echocardiography in mitral valve repair

OBJECTIVES

We sought to compare the diagnostic performance of 3-dimensional (3D) versus 2-dimensional (2D) echocardiography in patients with regurgitant mitral valve.

BACKGROUND

An accurate assessment of morphology and function of the mitral valve is essential for surgical repair. Two-dimensional echocardiography has certain spatial limitations that could be overcome by 3D imaging.

METHODS

Preoperative transesophageal 2D and 3D studies were compared with surgical findings in patients undergoing surgical repair for severe mitral regurgitation.

RESULTS

A total of 81 consecutive patients underwent surgical repair (2002-2004). There was a high concordance (88%-100%) between both 2D and 3D studies and surgical findings in classification of involved segments. 3D imaging more accurately classified A1 segment defects (P = .05) and commissural dysfunction (P = .02). The 2D study incorrectly classified 22 segments, mainly corresponding to complex disease. The 3D study incorrectly classified 14 segments, unrelated to complex disease. Good agreement (94%, kappa 0.845) was found between non-expert and expert interpretations of 3D images.

CONCLUSIONS

Three-dimensional echocardiography offers high accuracy in mitral valve evaluation. It may complement 2D study in patients with complex valve anatomy, where surgical decisions are more difficult. The images can be easily interpreted by professionals without a high degree of experience.

Mitral insufficiency and its different aetiologies: old and new insights for appropriate surgical indications and treatment

Mitral insufficiency, as many other fields in medicine, has witnessed profound changes in terms of knowledge, diagnostic process and therapeutic options. Mitral valve reconstruction has become the treatment of choice in the presence of a regurgitant valve, although numerous preoperative and operative clues have been shown to predict less satisfactory results of valve repair in the long term, calling for a careful revision of postoperative data and search for novel techniques of valve repair or reconsider valve replacement as an acceptable therapy in peculiar cases. Old scenarios, like rheumatic valve disease or acute endocarditis, are continuously under reassessment in an attempt to distinguish patient subsets amenable to tailored therapies, whereas new fields of intervention, like dilated cardiomyopathy, or better appraisal of pathophysiological mechanisms, like ischaemic mitral insufficiency, are emerging and represent new indications for surgical solutions. The most recent advances in the understanding of how some aetiologies and related mechanisms of mitral insufficiency exert substantial influence on the postoperative results represent new tools in the guidance of a more appropriate surgical decision-making.

Chronic Development of Ischaemic Mitral Regurgitation during Post-Infarction Remodelling

BACKGROUND/AIMS

Mitral regurgitation (MR) following myocardial infarction (MI) may be a (sub)acute complication which independently predicts reduced survival. We sought to evaluate the chronic development of MR as potential consequence of left-ventricular (LV) remodelling, the latter being a long-term process.

METHODS AND RESULTS

Retrospectively, 103 post-MI patients were included according to a standardised Doppler echocardiogram <3 months following MI (20 +/- 25 days post-MI) and a follow-up examination >6 months after the first examination (5.1 +/- 3.1 years post-MI). Patients were clinically followed up for 7.6 +/- 2.7 years. Group I patients were defined as those showing new development or deterioration in one of three grades of MR, and group II those without this criterion (MR grade acute 0.17 vs. 0.27, p = 0.7, and chronic 1.53 vs. 0.19, p < 0.0001). Patient characteristics were similar in respect of age, gender, size and location of infarction. However, group I patients had coronary artery disease with more vessels involved. With regard to echocardiographic parameters of significantly enlarged LV chamber size in group I vs. group II, the significant decrease in LV performance was more pronounced and occurred concomitant with a higher degree of symptomatic congestive heart failure and greater need for heart failure medications in group I. Mortality in group I patients was 39 versus 9% in group II patients (p = 0.0002), approximating an odds ratio of 6.4697 (95% confidence interval: 2.211-18.931).

CONCLUSION

First of all, this retrospective study indicates that MR may be detected in patients after MI during a long-term follow-up most probably due to geometric distortions of LV remodelling resulting in a significantly higher mortality. Since this process is known to become irreversible at a certain point, serial echocardiography may help to detect MR in post-MI patients and thus pave the way for appropriate treatment.

Physiologic Basis for the Surgical Treatment of Ischemic Mitral Regurgitation

Ischemic mitral regurgitation (MR) can complicate severe coronary artery disease and myocardial infarction. Ischemic MR results from left ventricular remodeling after myocardial infarction and can also accompany acute myocardial ischemia. The most common mechanism of ischemic MR is Carpentier's type IIIb dysfunction due to an apical and lateral displacement of papillary muscles leading to a tethering of the mitral leaflets. This apical tenting of the leaflets prevents the free margin from reaching the plane of the annulus, significantly reduces the surface of coaptation, and causes MR. Recent advances in imaging studies have led to a better understanding of the pathophysiology of this condition as well as to the development of innovative surgical approaches to treat this disease. Current research efforts have mainly focused on 2 directions: (1) percutaneous approaches to correct MR, and (2) surgical therapy to address the ventricular component of the disease. In this article, the authors define ischemic MR and review its pathophysiology, current management strategies, and future directions.

Cutting second-order chords does not prevent acute ischemic mitral regurgitation

BACKGROUND

Cutting anterior mitral leaflet second-order chordae has been proposed for repair in ischemic mitral regurgitation (IMR). We examined the efficacy of such chordal cutting in preventing acute IMR.

METHODS AND RESULTS

Six sheep underwent radiopaque marker placement (left ventricle, mitral annulus, papillary muscles [PMs], and leaflets). The largest second-order chord from each PM was encircled with exteriorized wire snares. Three-dimensional marker coordinates were obtained with biplane videofluoroscopy before and during acute ischemia (80 seconds of mid-circumflex occlusion). Color Doppler transesophageal echocardiography was used to grade MR on a 0 to 4+ scale. Data were acquired immediately before and after dividing second-order chordae. Slope of the end-diastolic volume-stroke work relationship (PRSW) was calculated to assess systolic function. Chordal cutting increased anterior leaflet inflection angle (155+/-12 versus 162+/-9 degrees; P=0.03), resulting in a flatter leaflet, but did not increase effective leaflet length (1.97+/-0.24 versus 2.08+/-0.23 cm; P=0.15); PRSW decreased (63+/-15 versus 56+/-12 mm Hg; P=0.008). Both before and after chordal cutting, ischemia caused: Septal-lateral annular dilation (P=0.005), posterior PM displacement away from the mid-septal annulus (P=0.06), increased leaflet tenting area (P=0.001), and increased leaflet tenting volume (P=0.002). Before chordal cutting, MR increased significantly during ischemia (0.5+/-0.3 versus 1.7+/-0.4; P<0.001), and IMR increased similarly even after the second-order chords were cut (0.7+/-0.4 versus 1.9+/-0.9; P<0.001).

CONCLUSIONS

Cutting second-order chordae resulted in LV systolic dysfunction and neither prevented nor decreased the severity of acute IMR, septal-lateral annular dilation, leaflet tenting area, or leaflet tenting volume.

Mitral regurgitation: overview of current surgical techniques and future developments

Mitral regurgitation is a complex disease with many different etiologies, underlying dysfunctions and histologic alterations. Surgical correction of this condition dramatically improves the life expectancy and life quality of affected patients. The structure of the mitral valve lends itself to many surgical techniques. The purpose of this review is to offer readers an overview on this subject.

Importance of Mitral Valve Second-Order Chordae for Left Ventricular Geometry, Wall Thickening Mechanics, and Global Systolic Function

Background— Mitral valvular–ventricular continuity is important for left ventricular (LV) systolic function, but the specific contributions of the anterior leaflet second-order “strut” chordae are unknown.

Methods and Results— Eight sheep had radiopaque markers implanted to silhouette the LV, annulus, and papillary muscles (PMs); 3 transmural bead columns were inserted into the mid-lateral wall between the PMs. The strut chordae were encircled with exteriorized wire snares. Three-dimensional marker images and hemodynamic data were acquired before and after chordal cutting. Preload recruitable stroke work (PRSW) and end-systolic elastance (E es ) were calculated to assess global LV systolic function (n=7). Transmural strains were measured from bead displacements (n=4). Chordal cutting caused global LV dysfunction: E es (1.48±1.12 versus 0.98±1.30 mm Hg/mL, P =0.04) and PRSW (69±16 versus 60±15 mm Hg, P =0.03) decreased. Although heart rate and time from ED to ES were unchanged, time of mid-ejection was delayed (125±18 versus 136±19 ms, P =0.01). Globally, the LV apex and posterior PM tip were displaced away from the fibrous annulus and LV base-apex length increased at end-diastole and end-systole (all +1 mm, P <0.05). Locally, subendocardial end-diastolic strains occurred: Longitudinal strain ( E 22 ) 0.030±0.013 and radial thickening ( E 33 ) 0.081±0.041 (both P <0.05 versus zero). Subendocardial systolic shear strains were also perturbed: Circumferential-longitudinal “micro-torsion” ( E 12 ) (0.099±0.035 versus 0.075±0.025) and circumferential radial shear ( E 13 ) (0.084±0.023 versus 0.039±0.008, both P <0.05).

Conclusion— Cutting second-order chords altered LV geometry, remodeled the myocardium between the PMs, perturbed local systolic strain patterns affecting micro-torsion and wall-thickening, and caused global systolic dysfunction, demonstrating the importance of these chordae for LV structure and function.