Mitral Implantation Research Articles

5-Year Prospective Evaluation of Mitral Valve-in-Valve, Valve-in-Ring, and Valve-in-MAC Outcomes: MITRAL Trial Final Results

BackgroundThe MITRAL (Mitral Implantation of Transcatheter Valves) trial is the first prospective trial to evaluate the safety and feasibility of balloon-expandable aortic transcatheter heart valves in patients with failed surgical bioprostheses or annuloplasty rings and severe mitral annular calcification treated with mitral valve-in-valve (MViV), valve-in-ring (MViR), or valve–in–mitral annular calcification (ViMAC). ObjectivesThe aim of this study was to evaluate 5-year outcomes among these patients. MethodsA multicenter prospective study was conducted among patients at high surgical risk at 13 U.S. sites. Patients underwent MViV (n = 30), MViR (n = 30), or ViMAC (n = 31) and were followed annually for 5 years. Kansas City Cardiomyopathy Questionnaire scores were obtained at baseline and follow-up visits. Echocardiograms were analyzed at independent core laboratories. ResultsA total of 91 patients underwent transcatheter mitral valve replacement (February 2015 to December 2017). The mean age was 74.3 ± 8.9 years. At 5-year follow-up, the lowest all-cause mortality was observed in the MViV group (21.4%), 94.7% of patients were in NYHA functional class I or II, and the mean mitral gradient was 6.6 ± 2.5 mm Hg. The MViR and ViMAC groups had higher all-cause mortality (65.5% and 67.9%), most survivors were in NYHA functional classes I and II (50% and 55.6%), and mean mitral gradients remained stable (5.8 ± 0.1 and 6.7 ± 2.5 mm Hg). Significant improvements in Kansas City Cardiomyopathy Questionnaire scores were observed when all 3 arms were pooled. ConclusionsMViV, MViR, and ViMAC procedures were associated with sustained improvement of heart failure symptoms and quality of life among survivors at 5 years. Transcatheter heart valve function remained stable in all 3 groups. Patients treated with MViV had excellent survival at 5 years, whereas survival was lower in the MViR and ViMAC groups, consistent with underlying disease severity. Patients with more residual mitral regurgitation had higher mortality.

Innovalve transcatheter mitral valve replacement system: Short-term pre-clinical study in pigs

Innovalve is a transcatheter mitral valve replacement (TMVR) system with a unique fixation system that aims to grasp the chordae in a rotational maneuver. ObjectivesThis study will examine the safety and efficacy of the transapical mitral implantation of Innovalve bioprosthesis in the porcine model. MethodsInnovalve MV bioprosthesis was implanted in the porcine model (5 pigs) for a duration of 30 days. ResultsThe Innovalve bioprosthesis was successfully implanted in all of the animals with accurate positioning, anchoring and good paravalvular sealing. At 30 days after implantation, all animals exhibited normal clinical status without evidence of cardiac impairment. The prosthetic valve seemed adequately adhered to the mitral annulus with fibrous tissue. ConclusionWe have demonstrated that the implantation of the Innovalve in healthy porcine subjects is feasible and safe and that the valve function and interaction with normal biological tissue is favorable and predictable.

2-Year Outcomes of Transcatheter Mitral Valve Replacement in Patients With Annular Calcification, Rings, and Bioprostheses

BackgroundThe MITRAL (Mitral Implantation of Transcatheter Valves) trial is the first prospective study for valve-in-mitral annular calcification (ViMAC), mitral valve-in-ring (MViR), and mitral valve-in-valve (MViV) using balloon-expandable aortic transcatheter heart valves. Procedural outcomes beyond 1 year are not well described. ObjectivesThis study evaluated 2-year outcomes in ViMAC, MViR, and MViV in the MITRAL trial. MethodsThis multicenter prospective study enrolled patients with severe MAC, prior failed mitral annuloplasty ring repair, or prior failed bioprosthetic MV replacement who were at high surgical risk at 13 U.S. sites. ResultsBetween February 1, 2015, and December 31, 2017, 91 patients were enrolled (31 with ViMAC, 30 with MViR, and 30 with MViV). In the ViMAC group, 2-year all-cause mortality was 39.3%, 66.7% were New York Heart Association (NYHA) functional class I-II, and mean MV gradient was 5.6 ± 2.0 mm Hg. In the MViR group, 2-year all-cause mortality was 50%, 65% were NYHA functional class I-II, and mean MV gradient was 6.5 ± 2.7 mm Hg. In the MViV group, 2-year all-cause mortality was 6.7%, 85% were NYHA functional class I-II, and mean MV gradient was 6.9 ± 2.4 mm Hg. At 2 years, all patients had ≤mild mitral regurgitation and survivors in all 3 arms showed sustained improvement in Kansas City Cardiomyopathy Questionnaire scores compared to baseline. ConclusionsUse of balloon-expandable aortic transcatheter heart valves in selected patients with severe MAC, failed annuloplasty ring, and bioprosthetic MV dysfunction is associated with improvements in symptoms, quality of life, and stable prosthesis function at 2-year follow-up. Between 1 and 2 years, the MViR group experienced higher mortality rates than the MViV and ViMAC groups.

Mitral implantation of a (Melody) pulmonary valve. A report of the first pediatric case in Colombia

Mitral implantation of a (Melody) pulmonary valve. A report of the first pediatric case in Colombia

4 year outcomes in a prospective evaluation of transcatheter mitral valve-in-valve, valve-in-ring and valve-in-mitral annular calcification: results from the MITRAL trial

Abstract Background The MITRAL Trial (Mitral Implantation of TRAnscatheter vaLves) evaluates the safety and feasibility of balloon-expandable aortic transcatheter heart valves in patients with severe mitral valve disease with mitral annular calcification (MAC), failed surgical rings or failed bioprostheses. Purpose We sought to evaluate 4-year outcomes of patients enrolled in the MITRAL trial. Methods This is a prospective study that enrolled 91 high surgical risk patients at 13 sites in the U.S. 30 patients underwent Mitral Valve-in-Valve (MViV), 30 Valve-in-Ring (MViR) and 31 Valve-in-MAC (ViMAC). 4-year outcomes of these patients were evaluated in this analysis. Primary endpoints and key serious adverse events including deaths were adjudicated by an independent Clinical Events Committee. Cardiac computed tomography (CT) and echocardiographic images were evaluated by independent CT and Echocardiographic Core Laboratories. Results Mean age was 74.3±8.9 years. Most patients undergoing MViV and ViMAC were female (MVIV=63.3%, MViR=36.7% and ViMAC=71%). Mean STS score was 9.2±6.6% (MViV 10.2±6.5%, MViR 8.7±4.7%, ViMAC=8.6±8.2%). All-cause mortality at 4 years was higher for ViMAC and MViR: MViV=6.9% (cardiovascular 3.4%), MViR=48.1% (cardiovascular 18.5%), ViMAC=51.9% (cardiovascular 29.6%), p=0.002 (Figure 1). At 4 years, all survivors had ≤1+ mitral regurgitation and most had none or trace mitral regurgitation (MViV=87.5, MViR=33.3% and ViMAC=100%). Mean mitral valve gradients remained stable (MViV=5.9±2.2 mmHg, MViR= 6.6±5.1 mmHg, ViMAC=5.1±1.0 mmHg), Figure 2. Most survivors experienced significant improvement of symptoms and were in NYHA class I-II at 4-year follow-up (MViV=78.9%, MViR=66.7% and ViMAC=66.7%). Conclusions MViV is associated with excellent outcomes at 4 years. MViR and ViMAC were associated with higher mortality at 4 years. However, most survivors in all groups experienced sustained improvement of symptoms and stable THV performance at 4 years. Whether survival bias had an impact on THV performance and improved symptoms at follow-up is not known and deserves further evaluation. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Unrestricted Research Grant from Edwards Lifesciences.

Transcatheter Mitral Valve-in-Valve Implantation with the Balloon-Expandable Myval Device.

Background: The vast majority of transcatheter valve-in-valve (ViV) mitral procedures have been reported with the SAPIEN family. We aimed to report the preliminary experience with the Myval balloon-expandable device in this setting. Methods: Multicenter retrospective study of high-risk surgical patients with mitral bioprosthesis degeneration undergoing transcatheter ViV implantation with Myval device. Results: A total of 11 patients from five institutions were gathered between 2019 and 2022 (age 68 ± 7.8, 63% women). The peak and mean transvalvular gradients were 27 ± 5 mmHg and 14.7 ± 2.3 mmHg, respectively, and the predicted neo-left ventricular outflow tract (neo-LVOT) area was 183.4 ± 56 mm2 (range: 171 to 221 mm2). The procedures were performed via transfemoral access in all cases (through echocardiography-guided transeptal puncture (81.8% transesophageal, 11.2% intracardiac)). Technical success was achieved in all cases, with no significant residual mitral stenosis in any of them (peak 7.2 ± 2.7 and mean gradient 3.4 ± 1.7 mmHg) and no complications during the procedure. There were no data of LVOT obstruction, migration, or paravalvular leak in any case. Mean hospital stay was 3 days, with one major vascular complication and no stroke. At 6-month follow-up, there was one case with suboptimal anticoagulation presenting an increase in the transmitral gradients (mean 15 mmHg) that normalized after optimization of the anticoagulation, but no other relevant events. Conclusions: Transseptal ViV mitral implantation with the balloon-expandable Myval device was feasible and safe avoiding redo surgery in high-risk patients with bioprosthesis degeneration.

Degenerative mitral valve stenosis diagnosis and management: literature review

Gustė Burneikaitė1 1Hospital of Vilnius University Santaros Clinics, Cardiology and Angiosurgery center, Lithuania Abstract Introduction. Mitral valve stenosis is fairly common valvular heart disease characterized by narrowing of the mitral valve orifice. The number of incidences of degenerative mitral valve stenosis are growing in developed countries. Accurate assessment and treatment of pathology is challenge in modern medicine due to changes in the structure of atrium and valve as well as other comorbidities in the aging population. Aim. To review information related to degenerative mitral valve stenosis especially its diagnosis and treatment options. Methods. The review of literature was conducted using medical database PubMed selecting publications investigating degenerative mitral valve stenosis and mitral annular calcification. Keywords were entered in the advanced search panel to gather data. After reviewing all the exclusion criteria, 42 scientific articles were included in this literature review. Review period is 2003 – 2022 with a few older publications. Results. Extensive mitral valve damage due to annular calcification is observed in degenerative mitral valve stenosis, which makes diagnosis and treatment particularly difficult. This pathology is most common in elderly patients with comorbidities, whose treatment options are limited. The potential for transcatheter mitral implantation can alleviate patient symptoms and improve prognosis, but this method is still not sufficiently analyzed. Conclusions. There are still no well-defined guidelines for diagnosis and treatment of degenerative mitral valve stenosis. The most promising diagnostic methods are 3D echocardiography and computed tomography of the heart, treatment – transcatheter mitral valve implantation. More detailed research is needed in this direction. Keywords: degenerative mitral valve stenosis, mitral annular calcification, diagnosis, management.

Intraoperative echocardiographic assessment of mitral regurgitation after mitral clip implantation: literature review

Intraoperative echocardiographic assessment of mitral regurgitation after mitral clip implantation: literature review

Complex Cause of Ischaemic Stroke in Patient after Mitral Bioprosthesis Implantation - A Case Report

Complex Cause of Ischaemic Stroke in Patient after Mitral Bioprosthesis Implantation - A Case Report

Prospective Evaluation of Transseptal TMVR for Failed Surgical Bioprostheses: MITRAL Trial Valve-in-Valve Arm 1-Year Outcomes.

The aim of this study was to assess 1-year clinical outcomes among high-risk patients with failed surgical mitral bioprostheses who underwent transseptal mitral valve-in-valve (MViV) with the SAPIEN 3 aortic transcatheter heart valve (THV) in the MITRAL (Mitral Implantation of Transcatheter Valves) trial. The MITRAL trial is the first prospective study evaluating transseptal MViV with the SAPIEN 3 aortic THV in high-risk patients with failed surgical mitral bioprostheses. High-risk patients with symptomatic moderate to severe or severe mitral regurgitation (MR) or severe mitral stenosis due to failed surgical mitral bioprostheses were prospectively enrolled. The primary safety endpoint was technical success. The primary THV performance endpoint was absence of MR grade≥2+ or mean mitral valve gradient≥10mmHg (30days and 1 year). Secondary endpoints included procedural success and all-cause mortality (30days and 1 year). Thirty patients were enrolled between July 2016 and October 2017 (median age 77.5 years [interquartile range (IQR): 70.3 to 82.8 years], 63.3% women, median Society of Thoracic Surgeons score 9.4% [IQR: 5.8% to 12.0%], 80% in New York Heart Association functional class III or IV). The technical success rate was 100%. The primary performance endpoint in survivors was achieved in 96.6% (28 of 29) at 30days and 82.8% (24 of 29) at 1 year. Thirty-day all-cause mortality was 3.3% and was unchanged at 1 year. The only death was due to airway obstruction after swallowing several pills simultaneously 29days post-MViV. At 1-year follow-up, 89.3% of patients were in New York Heart Association functional class I or II, the median mean mitral valve gradient was 6.6mmHg (interquartile range: 5.5 to 8.9mmHg), and all patients had MR grade≤1+. Transseptal MViV in high-risk patients was associated with 100% technical success, low procedural complication rates, and very low mortality at 1 year. The vast majority of patients experienced significant symptomalleviation, and THV performance remained stable at 1 year.

Prospective Evaluation of TMVR for Failed Surgical Annuloplasty Rings: MITRAL TrialValve-in-Ring Arm 1-Year Outcomes.

The authors report 1-year outcomes of high-risk patients with failed surgical annuloplasty rings undergoing transseptal mitral valve-in-ring (MViR) with the SAPIEN 3 aortic transcatheter heart valve (THV). The MITRAL (Mitral Implantation of Transcatheter Valves) trial is the first prospective study evaluating transseptal MViR with the SAPIEN 3 aortic THV in high-risk patients with failed surgical annuloplasty rings. Prospective enrollment of high-risk patients with symptomatic moderate to severe or severe mitral regurgitation (MR) or severe mitral stenosis and failed annuloplasty rings at 13 U.S. sites. The primary safety endpoint was technical success. The primary THV performance endpoint was absence of MR grade≥2+ or mean mitral valve gradient≥10mmHg (30days and 1 year). Secondary endpoints included procedural success and all-cause mortality (30days and 1 year). Thirty patients were enrolled between January 2016 and October 2017 (median age 71.5 years [interquartile range: 67.0 to 76.8 years], 36.7% women, median Society of Thoracic Surgeons score 7.6% [interquartile range: 5.1% to 11.8%], 76.7% in New York Heart Association functional class III or IV). Technical success was 66.7% (driven primarily by need for a second valve in 6 patients). There was no intraprocedural mortality or conversion to surgery. The primary performance endpoint was achieved in 85.7% of survivors at 30days (24 of 28) and 89.5% of patients alive at 1 year with echocardiographic data available (17 of 19). All-cause mortality at 30days was 6.7% and at 1 year was 23.3%. Among survivors at 1-year follow-up, 84.2% were in New York Heart Association functional class I or II, the median mean mitral valve gradient was 6.0mmHg (interquartile range: 4.7 to 7.3mmHg), and all had≤1+ MR. Transseptal MViR was associated with a 30-day mortality rate lower than predicted by the Society of Thoracic Surgeons score. At 1 year, transseptal MViR was associated with symptom improvement and stable THV performance.

Complex cause of ischaemic stroke in patient after mitral bioprosthesis implantation- A case report

Complex cause of ischaemic stroke in patient after mitral bioprosthesis implantation- A case report

Experimental Evaluation of a Novel Percutaneous Transseptal Catheter-Based Mitral Valve Replacement Technology.

Transcatheter mitral valve replacement is a novel therapeutic approach aiming to treat patients with severe mitral regurgitation. This study aimed to evaluate the biological and technical performance of a novel transseptal transcatheter mitral valve replacement system (Cephea Valve Technologies, Santa Cruz, CA) in a preclinical model. Biological performance and healing response were evaluated following open-heart surgical implantation procedures in 10 sheep utilizing an antegrade transatrial access. Valve performance was assessed with fluoroscopy, echocardiography, and histology at 30 (n=2), 60 (n=3), and 90 days (n=5). Feasibility of transseptal valve delivery and performance was tested acutely in 10 pigs. In the chronic studies, all animals survived without problems until completion of the study. The hemodynamics of the study valves were excellent with low rates of paravalvular leak. There was no left ventricular outflow tract obstruction. Pathological evaluation showed excellent position and condition of the mitral implants without evidence for thrombosis, endocarditis, or excessive calcification. Subsequently, mitral valves were implanted in 10 pigs using a dedicated transseptal delivery system. The implants remained in stable position with excellent hemodynamic profile. Correct valve position and function was confirmed by echocardiography and autopsy. The transseptal delivery of the Cephea transcatheter mitral valve replacement system in an experimental model was feasible and safe. The chronic studies demonstrated a favorable healing response. Further human studies are needed to evaluate the performance of this novel valve system in patients with severe mitral regurgitation.

Persistent Reduction of Functional Mitral Regurgitation by Transvalvular Mitral Bridge Implantation - Durability and Effectiveness of the Repair at 4 years

Persistent Reduction of Functional Mitral Regurgitation by Transvalvular Mitral Bridge Implantation - Durability and Effectiveness of the Repair at 4 years

A novel tissue treatment to reduce mineralization of bovine pericardial heart valves

ObjectiveWith the increasing use of bioprostheses worldwide, continuous efforts have been made to improve tissue durability. We introduce a new treatment for bovine pericardium combining octanediol-ethanol based phospholipid removal with taurine-based glutaraldehyde neutralization and storage in an aldehyde-free solution (FREE). MethodsTreated tissues were evaluated by mechanical and biochemical characterization, phospholipid content, aldehyde levels, cell cultures on pericardial samples (L929 fibroblasts and human umbilical vein endothelial cells), rat subcutaneous implantations, and long-term juvenile sheep mitral valve implantations (n = 3). Comparisons were made to glutaraldehyde-fixed bovine pericardium or to samples from commercially available biological valves (ie, Trifecta [St Jude Medical, Saint Paul, Minn] and Perimount Magna Ease [Edwards Lifesciences, Irvine, Calif]). ResultsFREE-treated pericardium had similar mechanical strength and biochemical properties as commercially available valves. Compared with glutaraldehyde-only samples, FREE-treated samples showed lower phospholipid levels (P < .01), significantly better growth of L929 fibroblasts, and lower calcification levels in rat subcutaneous implants (P < .01). Compared with samples from Linx- (Trifecta) and ThermaFix-treated (Perimount Magna Ease) valves, similar low levels of phospholipids were observed as were similar low calcification levels in subcutaneous implants, but tissue extractions from FREE-treated samples showed the lowest levels of extracted aldehydes (P < .01). Mitral implants of FREE-treated valves in juvenile sheep had excellent hemodynamic behavior without any sign of degeneration or calcification at 5 months. ConclusionsThe new FREE treatment combines an adequate phospholipid reduction and aldehyde neutralization with storage in an aldehyde-free solution. This combination enhances the anticalcification properties and may thereby improve long-term durability of the tissue.

Transcatheter Annuloplasty for Mitral Regurgitation with an Adjustable Semi-Rigid Complete Ring: Initial Experience with the Millipede IRIS Device

ABSTRACTBackground: Complete, semi-rigid annuloplasty rings result in more durable reduction of mitral regurgitation (MR) over time than partial or flexible bands. We herein report the initial experience with the IRIS transcatheter adjustable semi-rigid complete annuloplasty ring.Methods: Seven patients were treated with the IRIS ring. Inclusion criteria included: 3–4+ functional MR, symptomatic New York Heart Association (NYHA) II–IV, and left ventricle (LV) end systolic dimension ≤ 65 mm. Exclusion criteria included: left ventricular ejection fraction (LVEF) < 20%, aortic valve disease, right-sided heart failure, and pulmonary artery systolic pressure (PASP) > 70 mmHg. Baseline and 30-day transthoracic echocardiography and computed tomography (CT) imaging was performed.Results: In Phase 1, four patients had surgical IRIS mitral ring implantation, and two had rings placed for associated functional tricuspid regurgitation (TR). In Phase 2, three patients had transfemoral, transseptal delivery of the IRIS mitral ring. There was no procedural death, stroke, or myocardial infarction (MI). One patient from Phase 1 expired 2 days post-procedure from chronic renal failure complications. The mitral septal-lateral (SL) diameter was reduced from 38.0 ± 4.1 mm to 25.9 ± 4.9 mm at 30 days (31.8% SL reduction, n = 7). MR was reduced from baseline 3–4+ to 0–1+ in all patients at 30 days. There were improvements in NYHA class, and there was a decrease in diastolic LV volumes from 182.4 ± 54.3mL to 115.3 ± 98.8 mL at 30 days (36.8% reduction). In the two patients with tricuspid annuloplasty, TR grade and tricuspid annular diameter reductions were baseline 4+ to 1+ at 30 days (37% annular reduction) and baseline 3+ to 0 at 30 days (36% annular reduction).Conclusion: This initial experience with the Millipede IRIS adjustable semi-rigid complete ring has demonstrated robust reductions in the mitral SL diameter, MR grade, and LV volumes.

Abstract 23085: 30-Day Outcomes of Transseptal Transcatheter Mitral Valve Replacement for Failed Surgical Bioprostheses (Mitral Valve-in-Valve): The MITRAL Trial (Mitral Implantation of TRAnscatheter vaLves)

Introduction: Transcatheter mitral valve replacement (TMVR) using aortic transcatheter heart valves (THV) is developing as an alternative to surgery for patients with severely degenerated mitral valve (MV) bioprostheses. Retrospective self-reported registries have collected outcomes on these TMVR procedures in the STS/ACC Transcatheter Valve Therapy Registry and in the Valve-in-Valve International Database. Most reported TMVR procedures for failed surgical bioprostheses have been performed using a transapical access approach. A prospective comprehensive evaluation of mitral Valve-in-Valve (VIV) outcomes, including transseptal access has not previously been conducted. Objectives: To evaluate in-hospital and 30-day clinical outcomes of transseptal mitral VIV with SAPIEN 3 THV in patients with very high surgical risk. Methods: Prospective enrollment of very high surgical risk patients with symptomatic severely degenerated MV surgical bioprostheses in 30 patients at 15 sites in the U.S. Candidates were assessed by a case review committee prior to approval. Baseline qualifying echocardiograms and cardiac CT studies were analyzed by independent core labs. Echocardiograms, cardiac CT studies and neurology evaluations were also performed after mitral VIV procedures. Clinical events were adjudicated by a clinical events committee and safety was monitored by a data safety monitoring board. Results: 26 patients have been enrolled between July 2016 and June 2017. Mean age was 83 years, 62% female, mean STS score was 10% and 62% were in New York Heart Association class III or IV. Transseptal access was used in all procedures. Technical success was achieved in all patients and there was no in-hospital mortality. There was no 30-day cardiovascular mortality and 4% (1 patient) 30-day all-cause mortality (1 patient died of asphyxia on day 29 after choking on pills at home), which was lower than the 30-day mortality in the TVT registry (9%). Detailed procedural, in-hospital and 30-day outcomes will be presented on the complete cohort of 30 patients. Conclusions: In patients without surgical alternatives, transseptal mitral ViV procedures in failed surgical bioprostheses are associated with high technical and procedural success and low 30-day mortality.

Transseptal transcatheter mitral valve-in-valve: A step by step guide from preprocedural planning to postprocedural care.

Transcatheter mitral valve replacement has been successfully performed with the use of aortic transcatheter heart valves in hundreds of patients worldwide with severe dysfunction of a degenerated mitral bioprosthesis and high surgical risk for repeat operation. The delivery approach in the vast majority of the mitral valve-in-valve procedures has been transapical. Although the transseptal approach may be more technically challenging, it is less invasive and may be preferred by patients. Data from case series and a large international registry suggest that patients treated with transseptal mitral valve-in-valve have faster recovery, more improvement in left ventricular ejection fraction and possibly lower mortality compared with patients treated with transapical approach. A prospective clinical trial, the MITRAL trial (Mitral Implantation of TRAnscatheter vaLves) is evaluating the safety and feasibility of transvenous transseptal mitral valve-in-valve. The experience from this trial has allowed us to improve our procedural approach. In anticipation of a wider adoption of the transseptal approach for mitral valve-in-valve, we describe our current method step-by-step from planning the procedure through postprocedural management. This is an evolving technique that has changed with experience and the transition to newer generation transcatheter heart valve devices. We discuss the use of cardiac computed tomography for planning the procedure including transseptal puncture and valve size selection, provide procedural and technical tips, and discuss postprocedural care.

Fully Percutaneous Transthoracic Left Atrial Entry and Closure as a Potential Access Route for Transcatheter Mitral Valve Interventions

Percutaneous access for mitral interventions is currently limited to transapical and transseptal routes, both of which have shortcomings. We hypothesized that the left atrium could be accessed directly through the posterior chest wall under imaging guidance. We tested percutaneous transthoracic left atrial access in 12 animals (10 pigs and 2 sheep) under real-time magnetic resonance imaging or x-ray fluoroscopy plus C-arm computed tomographic guidance. The pleural space was insufflated with CO2 to displace the lung, an 18F sheath was delivered to the left atrium, and the left atrial port was closed using an off-the-shelf nitinol cardiac occluder. Animals were survived for a minimum of 7 days. The left atrial was accessed, and the port was closed successfully in 12/12 animals. There was no procedural mortality and only 1 hemodynamically insignificant pericardial effusion was observed at follow-up. We also successfully performed the procedure on 3 human cadavers. A simulated trajectory to the left atrium was present in all of 10 human cardiac computed tomographic angiograms analyzed. Percutaneous transthoracic left atrial access is feasible without instrumenting the left ventricular myocardium. In our experience, magnetic resonance imaging offers superb visualization of anatomic structures with the ability to monitor and address complications in real-time, although x-ray guidance seems feasible. Clinical translation seems realistic based on human cardiac computed tomographic analysis and cadaver testing. This technique could provide a direct nonsurgical access route for future transcatheter mitral implantation.

A Pig Model of Ischemic Mitral Regurgitation Induced by Mitral Chordae Tendinae Rupture and Implantation of an Ameroid Constrictor

A miniature pig model of ischemic mitral regurgitation (IMR) was developed by posterior mitral chordae tendinae rupture and implantation of an ameroid constrictor. A 2.5-mm ameroid constrictor was placed around the left circumflex coronary artery (LCX) of male Tibetan miniature pigs to induce ischemia, while the posterior mitral chordae tendinae was also ruptured. X-ray coronary angiography, ECG analysis, echocardiography, and magnetic resonance imaging (MRI) were used to evaluate heart structure and function in pigs at baseline and one, two, four and eight weeks after the operation. Blood velocity of the mitral regurgitation was found to be between medium and high levels. Angiographic analyses revealed that the LCX closure was 10–20% at one week, 30–40% at two weeks and 90–100% at four weeks subsequent ameroid constrictor implantation. ECG analysis highlighted an increase in the diameter of the left atria (LA) at two weeks post-operation as well as ischemic changes in the left ventricle (LV) and LA wall at four weeks post-operation. Echocardiography and MRI further detected a gradual increase in LA and LV volumes from two weeks post-operation. LV end diastolic and systolic volumes as well as LA end diastolic and systolic volume were also significantly higher in pig hearts post-operation when compared to baseline. Pathological changes were observed in the heart, which included scar tissue in the ischemic central area of the LV. Transmission electron microscopy highlighted the presence of contraction bands and edema surrounding the ischemia area, including inflammatory cell infiltration within the ischemic area. We have developed a pig model of IMR using the posterior mitral chordae tendineae rupture technique and implantation of an ameroid constrictor. The pathological features of this pig IMR model were found to mimic the natural history and progression of IMR in patients.