Comparison of clinical outcomes in patients undergoing mitral valve replacement with mechanical or biological substitutes: a 20 years cohort

Valve-in-valve transcatheter mitral valve replacement versus redo-surgical mitral valve replacement for degenerated bioprosthetic mitral valves: A systematic review and meta-analysis

Bioprosthetic mitral valve degeneration is traditionally treated with Redo-SMVR, but the latest ViV-TMVR procedure offers a less invasive and lower risk alternative. A systematic literature search was conducted on Cochrane Central, Scopus, and Medline (PubMed interface) electronic databases from inception till 15th April 2024. We used risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous outcomes. We included a total of eleven studies with 11,931 patients in the final quantitative and qualitative analysis. When comparing ViV-TMVR with Redo-SMVR, no significant difference was found for 30-day mortality (P = 0.13) and 1-year mortality (P = 0.91), whereas patients in the ViV-TMVR showed significantly reduced incidence of stroke (P < 0.00001), In-hospital mortality (P), bleeding complications (P = 0.003), AKI (P = 0.0006), arrhythmias (P = 0.01), LVOT obstruction (P = 0.04), and PPI (P < 0.00001). Furthermore, no significant difference was observed between either group when comparing vascular complications (P = 0.97), 2-year mortality (P = 0.60) and 3-year mortality. ViV-TMVR was associated with a significant risk of paravalvular leakage (P = 0.008). Although, ViV-TMVR reduces the risk of complications associated with Redo-SMVR, larger studies are imperative to reach conclusive results.

Mechanical versus biological mitral valve replacement: Insights from propensity score matching on survival and reoperation rates

OBJECTIVES

Patients with symptomatic mitral valve disease unsuitable for repair can be sufficiently treated with surgical mitral valve replacement. The decision between biological and mechanical mitral valve replacement can be difficult, especially due to the question of the lesser of 2 evils: anticoagulation versus reoperation.

METHODS

This single-center, retrospective study included all patients undergoing mitral valve replacement between 2001 and 2020. Thirty-day mortality and periprocedural complications were analyzed. Propensity score matching adjusted for age, gender, weight, height, endocarditis, diabetes, hypertension, peripheral arterial occlusive disease, atrial fibrillation, chronic kidney disease, cancer, and history of neurological disorders was performed. After propensity score matching, survival and cumulative incidence of reoperation at time of follow-up were analyzed.

RESULTS

The study included 2027 patients in 2 main groups: 1658 patients with biological mitral valve replacement and 369 patients with mechanical mitral valve replacement; 51.2% were male. Age at surgery was 65.9 ± 12.9 years. Median follow-up time was 6.83 years (interquartile range, 1.11-10.61 years). Concomitant procedures were performed in 1467 cases (72.4%). Propensity score matching yielded comparable groups of 339 pairs. Both groups showed comparable survival (P = .203). Survival after mechanical mitral valve replacement and biological mitral valve replacement was comparable for all analyzed time points over the course of 20 years. Patients with mechanical mitral valve replacement showed a significantly lower cumulative incidence for reoperation (20 years: 15% vs 59%, P < .001).

CONCLUSIONS

Follow-up of 20 years at a high-volume center demonstrates comparable survival after mechanical or biological mitral valve replacement, whereas reoperation rates are significantly lower after mechanical mitral valve replacement.

Long-Term Outcomes of Bioprosthetic Valves in the Mitral Position: A Pooled Meta-Analysis of Reconstructed Time-to-Event Individual Patient Data

Bioprosthetic mitral valve replacement (bMVR) use is increasing; however, data regarding long-term durability are lacking. We sought to perform a reconstructed individual patient data meta-analysis from published Kaplan-Meier curves to ascertain survival, freedom from valve degeneration, and reoperation in studies published since 2010. We explored the effects of age and valve type (bovine pericardial or porcine valve) on outcomes. We searched MEDLINE, OVID, Embase, and Cochrane CENTRAL for studies reporting at least 3 years of follow-up after bMVR and published since 2010. The Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool was used to assess methodologic quality. Kaplan-Meier curves were digitized to extract individual patient data and reconstructed estimates for overall survival, freedom from structural valve deterioration (SVD), and freedom from reoperation. A total of 20 studies (16,465 patients) were included. A total of 9 studies reported on porcine valves, 6 reported on bovine, and 7 did not specify the valve type. The overall survival after bMVR at 15 years was 40% (confidence interval 38% to 42%), freedom from reoperation at 15 years was 79% (confidence interval 76% to 82%), and freedom from SVD at 15 years was 64% (58% to 70%). Freedom from SVD was improved in the 70+ years age group (93% up to 25 years, hazard ratio 6.6 [2.5 to 17] for 18 to 59 vs >70 years, p <0.0001). There was no difference in valve durability or survival between bovine pericardial or porcine valves. In this meta-analysis of patients who underwent bMVR using newer generation valves, the inverse relation between age and SVD was reiterated in the 70+ years age group. The prosthesis type made no difference in the outcomes.

Long-term outcomes of bioprosthetic valves in the mitral position a systematic review of studies published over the last 20 years

OBJECTIVES

Although the use of bioprostheses for mitral valve replacement (bMVR) is on the rise, their long-term durability is not well described. Defining bMVR durability will be instrumental in setting the standard against which the performance of transcatheter mitral replacement is to be judged against. The authors of this systematic review aimed to identify, assess the quality and review the outcomes in studies reporting on long-term outcomes after bMVR published over the last 20 years.

METHODS

Medline, Embase and Cochrane CENTRAL were searched for studies that have reported outcomes beyond a minimum of 5 years of follow-up after bMVR. Cohort characteristics, definitions of structural valve deterioration (SVD) and outcomes were summarized. The risk of bias in included studies was assessed using the Cochrane QUIPS tool.

RESULTS

Twenty-one studies, including 15 833 patients, were identified. Sixty-four percent of all implants were porcine and the remaining bovine pericardial. Freedom from SVD at 10 years ranged from 58.9% to 100% and at 15 years from 58.3% to 93%. Freedom from reoperation ranged from 65% to 98.7% at 10 years and 78.5% to 91% at 15 years. Information on native valve pathology or dominant haemodynamic lesion was missing in 25% and 66% of studies, respectively. Reports of postoperative echocardiography were lacking, despite the heavy reliance on echocardiography for SVD diagnosis.

CONCLUSIONS

There is considerable variability in reporting bMVR long-term outcomes. As such, it is difficult to generate an unbiased, generalizable understanding of long- term outcomes after bMVR across the spectrum of mitral disease phenotypes.

Mechanical or biologic prostheses for mitral valve replacement: A systematic review and meta-analysis

Either a mechanical or bioprosthetic valve is used in patients undergoing mitral valve replacement (MVR). However, the optimal mitral prosthesis remains controversial. The aim of this meta‐analysis was thus to compare outcomes between mechanical mitral valve replacement (MVRm) and bioprosthetic mitral valve replacement (MVRb) for MVR patients. We searched Embase, PubMed, Web of Science, and Cochrane Library databases from January 1, 2000 to October 31, 2021 for studies that directly compared surgical outcomes of MVRm and MVRb. A total of 22 studies with 35 903 patients were included in the meta‐analysis (n = 23 868 MVRm and n = 12 035 MVRb). The MVRm group displayed lower long‐term all causes mortality (HR, 0.84; 95% confidence interval [CI]: 0.77−0.91; p < .0001; I² = 51%), and fewer mitral reoperation (hazard ratio [HR]: 0.34; 95% CI: 0.23−0.50; p < .00001; I² = 74%) than MVRb group. However, the MVRm group was associated with a greater risk of major bleeding events (HR: 1.21; 95% CI: 1.14−1.29; p < .00001; I² = 0%), stroke and systemic embolism (HR: 1.20; 95% CI: 1.10−1.32; p < .0001; I² = 0%) in matched or adjusted data. No significant difference was observed between MVRm and MVRb on operative mortality in matched/adjusted group (risk ratios: 0.83; 95% CI: 0.66−1.05; p = .12; I² = 0%). The results were consistent with patients aged under 70 years old. Patients who received a MVRm is associated with 16% lower risk of long‐term mortality and 66% lower risk of mitral reoperation, but 20% greater risk of stroke or systemic embolism, 21% greater risk of major bleeding compared with MVRb in matched/adjusted studies group, which were consistent to patients younger than the age of 70 years who underwent MVR.

Interdisciplinary Methods for Zoonotic Tissue Acellularization for Natural Heart Valve Substitute of Biomimetic Materials

The goal of this work was to create a bioactive tissue-based scaffold using multi-disciplinary engineering materials and tissue engineering techniques. Materials & methods: Physical techniques such as direct laser interference lithography and proton radiation were selected as alternative methods of enzymatic and chemical decellularization to remove cells from a tissue without degradation of the extracellular matrix nor its protein structure. This study was an attempt to prepare a functional scaffold for cell culture from tissue of animal origin using new physical methods that have not been considered before. The work was carried out under full control of the histological and molecular analysis. Results & conclusions: The most important finding was that the physical methods used to obtain the decellularized tissue scaffold differed in the efficiency of cell removal from the tissue in favour of the laser method. Both the laser method and the proton method exhibited a destructive effect on tissue structure and the genetic material in cell nuclei. This effect was visible on histology images as blurred areas within the cell nucleus. The finite element 3D simulation of decellularization process of the three-layer tissue of animal origin sample reflected well the mechanical response of tissue described by hyperelastic material models and provided results comparable to the experimental ones.

Current state of transcatheter mitral valve implantation in bioprosthetic mitral valve and in mitral ring as a treatment approach for failed mitral prosthesis

With heightened awareness of mitral valve disease and improvement in surgical techniques, the use of mitral valve bioprostheses has increased. There is a large aging population with prior surgical valvular interventions. Limited durability of the prosthesis due to valvular degeneration over time may necessitate the need for repair or replacement of the prior prosthesis in the future. This usually entails another surgical intervention in this population with elevated risk for a reoperation. There is an ongoing clinical need for newer, less invasive options that are feasible and carry a lower complication rate. The advent of transcatheter heart valve (THV) therapies has opened up a wide range of therapeutic options for treatment of a failed bioprosthesis. Their safety and feasibility are now well established. This article serves as a review of the currently available THVs for implantation in the mitral position, the pre-procedural assessment, the challenges associated with implantation, as well as outcomes associated with a mitral valve-in-valve (VIV) and a mitral valve-in-ring (VIR) procedure.

Multimodality Cardiac Imaging for Procedural Planning and Guidance of Transcatheter Mitral Valve Replacement and Mitral Paravalvular Leak Closure

Transcatheter mitral valve interventions are an evolving and growing field in which multimodality cardiac imaging is essential for diagnosis, procedural planning, and intraprocedural guidance. Currently, transcatheter mitral valve-in-valve with a balloon-expandable valve is the only form of transcatheter mitral valve replacement (TMVR) approved by the FDA, but valve-in-ring and valve-in-mitral annular calcification interventions are increasingly being performed. Additionally, there are several devices under investigation for implantation in a native annulus. Paravalvular leak (PVL) is a known complication of surgical or transcatheter valve implantation, where regurgitant flow occurs between the prosthetic sewing ring and the native mitral annulus. We sought to describe the role and applications of multimodality cardiac imaging for TMVR, and PVL closure, including the use of Cardiovascular Computed Tomography Angiography and 3-Dimensional Transesophageal Echocardiography for diagnosis, prosthetic valve evaluation, pre-procedural planning, and intraprocedural guidance, as well as evolving technologies such as fusion imaging and 3D printing.

Mitral valve prosthesis choice in patients <70 years: A systematic review and meta-analysis of 20 219 patients

BACKGROUND

The optimal mitral prosthesis in young patients is unclear. This systematic review and meta-analysis were performed to compare outcomes between bileaflet mechanical mitral valve replacement (mMVR) and bioprosthesis mitral valve replacement (bioMVR) for MVR patients aged less than 70 years.

METHODS

We searched MEDLINE and EMBASE databases from inception to July 2018 for studies comparing surgical outcomes of mMVR vs bioMVR.

RESULTS

There were 14 observational studies with 20 219 patients (n = 14 658 mMVR and n = 5561 bioMVR). Patients receiving an mMVR were younger with fewer comorbidities including renal failure, dialysis, and less-infective endocarditis (P < .001). The estimated 10-year mortality ranged from 19% to 49% for mMVR and 22% to 58% for bioMVR among studies. Comparing matched or adjusted data, mMVR was associated with lower operative (risk ratio [RR]: 0.61; 95% confidence interval [CI]: 0.39, 0.94; P = .03) and long-term (HR: 0.81; 95% CI: 0.71, 0.92; P = .002) mortality at a median follow-up of 8 years (IQR: 6-10 years). Estimated 10-year risk for mitral valve reoperation ranged from 0% to 8% for mMVR and 8% to 22% for bioMVR among matched/adjusted studies. mMVR was associated with lower matched/adjusted risk of reoperation (HR: 0.35; 95% CI: 0.19, 0.65; P = .001) but with greater risk of bleeding (HR: 1.59; 95% CI: 1.19, 2.13; P = .002) and a trend to greater risk of stroke and embolism (HR: 1.70; 95% CI: 0.92, 3.15; P = .09).

CONCLUSION

Mechanical MVR in patients aged less than 70 years is associated with a lower risk of operative mortality as well as a 20% lower risk of long-term death and 65% lower risk of mitral valve reoperation but 60% greater risk of bleeding compared with bioMVR in matched or adjusted data.

Trends, characteristics, in-hospital outcomes and mortality in surgical mitral valve replacement among patients with and without COPD in Spain (2001-2015)

PURPOSE

We examined trends, characteristics and in-hospital outcomes in mechanical and bioprosthetic surgical mitral valve replacement (SMVR) among patients with and without chronic obstructive pulmonary disease (COPD) in Spain from 2001 to 2015. We also identified factors associated with in-hospital mortality (IHM) in both groups of patients according to the implanted valve type.

METHODS

We analyzed data from the Spanish National Hospital Discharge Database for patients aged 40 years or over. We selected admissions of patients whose medical procedures included SMVR. We grouped hospitalizations by COPD status.

RESULTS

Over 43,024 patients identified, 83.63% underwent mechanical mitral valve replacement and 16.37% bioprosthetic valve (6.71% and 7.78% with COPD, respectively). The incidence of SMVR decreased for mechanical valves and increased for bioprosthetic valves over time in both groups of patients. The incidence of SMVR admissions was lower among COPD patients than in those without COPD, both for mechanical and bioprosthetic valves. IHM decreased significantly over time, regardless of the type of valve, in both groups of patients. COPD was associated with a significant increase in IHM, but only among patients who underwent bioprosthetic SMVR (OR 1.32, 95% CI 1.01-1.73).

CONCLUSIONS

The incidence of mechanical SMVR decreased while that of bioprosthetic SMVR increased over time in both groups of patients. COPD patients were less surgically operated than non-COPD patients for both valve types. In COPD patients, bioprosthetic SMVR was proportionally more used than mechanical SMVR. Mortality decreased over time for both valve types in patients with and without COPD. COPD increased in-hospital mortality among patients undergoing a biological SMVR.

Long-term outcome after mitral valve replacement using biological versus mechanical valves

BACKGROUND

This study compared long-term outcomes of biological and mechanical mitral valve replacement (MVR) in patients requiring replacement of the mitral valve where repair was not feasible.

METHODS

A single-centre registry of patients receiving MVR between 2005 and 2015 was established. Thirty-day mortality and long-term outcomes were analysed and compared.

RESULTS

Three hundred twenty four patients underwent MVR (265 biological; 59 mechanical valves). Patients receiving biological valves were older (p < 0.001), had a higher log EuroSCORE (p < 0.001) and received less minimally invasive surgery (p < 0.001). Immediate procedural mortality was 1.9%, which only occurred in the biological valve group. At 30 days, 9.0% of patients had died, 4.0% experienced stroke, 8.0% received a pacemaker and 10.5% suffered an acute renal failure. The rate of re-thoracotomy (14.2%) was lower in the biological (12.5%) than in the mechanical valve group (22.0%; adjOR 0.45 [0.20-1.00]; p = 0.050). Frequent long-term complications were stroke (9.2%) and bleeding (4.8%), with bleeding complications being higher in the mechanical valve group (p = 0.009). During the follow-up period biological valves showed a numerically higher survival rate during the first years, which shifted after 3 years in favour of mechanical valves. At 10 years, survival rates were 62.4% vs. 77.1% in the biological and mechanical valve groups (p = 0.769). Hazard ratio after adjustment was 0.833 (95% CI 0.430-1.615).

CONCLUSION

These data confirm that mechanical valve implantation is associated with an increased risk of bleeding. While there was a potential survival benefit during the first years after surgery for patients receiving a biological valves the difference became insignificant after a follow-up of 10 years.

Impact of type 2 diabetes mellitus in the utilization and in-hospital outcomes of surgical mitral valve replacement in Spain (2001-2015)

Background

The main aims of this study were to examine the incidence and in-hospital outcomes of mechanical and bioprosthetic surgical mitral valve replacement (SMVR) among patients with and without T2DM.

Methods

We performed a retrospective study using the Spanish National Hospital Discharge Database from 2001 to 2015. We included patients with SMVR codified in their discharge report. We grouped admissions by diabetes status. Propensity score matching (PSM) was used to compare outcomes of isolated SMVR.

Results

We identified 42,937 patients (16.41% with T2DM). Incidence rates of mechanical and bioprosthetic SMVR were higher among T2DM patients than among non-T2DM patients. In both groups of patients, the use of bioprosthetic SMVR increased over time. The use of mechanical valves remained stable among T2DM patients. In T2DM and non-T2DM patients with mechanical SMVR, in hospital mortality (IHM) and MACCE decreased significantly (p < 0.001) from 2001 to 2015. T2DM patients had an overall 11.37% IHM, compared with 10.76% among non-T2DM patients (p = 0.176). Regarding MACCE figures were 14.72% vs. 14.22% (p = 0.320) after mechanical SMVR. Total crude IHM were 14.29% for T2DM patients and 15.13% for those without T2DM with bioprosthetic SMVR (p = 0.165) and 18.22 vs. 19.64%, for a MACCE (p = 0.185). Using PSM we found that the IHM and the MACCE of isolated SMVR did not differ significantly between patients with or without T2DM beside the type of valve replacement. Among T2DM patients, those who received bioprosthetic valves had higher IHM (14.29% vs. 11.37%; p = 0.003) and a higher rate of MACCE (18.22% vs. 14.72%; p = 0.001) than T2DM patients with mechanical SMVR.

Conclusions

In Spain from 2001 to 2015, the incidence rates of hospitalization to undergo mechanical or bioprosthetic SMVR were higher among the population suffering T2DM than among the non-T2DM population. In both groups of patients the use of bioprosthetic SMVR increased over time and the use of mechanical valves remained stable in T2DM. T2DM patients have IHM and MACCE after mechanical and bioprosthetic SMVR which are not significantly different to those found among non-diabetic patients. Among T2DM patients, the crude IHM was significantly higher in those who received a bioprosthetic SMVR than those with mechanical SMVR.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0866-5) contains supplementary material, which is available to authorized users.

Tissue-Engineered Heart Valves: A Call for Mechanistic Studies

Heart valve disease carries a substantial risk of morbidity and mortality. Outcomes are significantly improved by valve replacement, but currently available mechanical and biological replacement valves are associated with complications of their own. Mechanical valves have a high rate of thromboembolism and require lifelong anticoagulation. Biological prosthetic valves have a much shorter lifespan, and they are prone to tearing and degradation. Both types of valves lack the capacity for growth, making them particularly problematic in pediatric patients. Tissue engineering has the potential to overcome these challenges by creating a neovalve composed of native tissue that is capable of growth and remodeling. The first tissue-engineered heart valve (TEHV) was created more than 20 years ago in an ovine model, and the technology has been advanced to clinical trials in the intervening decades. Some TEHVs have had clinical success, whereas others have failed, with structural degeneration resulting in patient deaths. The etiologies of these complications are poorly understood because much of the research in this field has been performed in large animals and humans, and, therefore, there are few studies of the mechanisms of neotissue formation. This review examines the need for a TEHV to treat pediatric patients with valve disease, the history of TEHVs, and a future that would benefit from extension of the reverse translational trend in this field to include small animal studies.

Transcatheter Mitral Valve-in-Valve Therapy

Valve-in-valve and valve-in-ring transcatheter mitral valve replacement can be used in for the treatment of inoperable patients with failing mitral surgical bioprosthesis or valve repairs. Preprocedural multi-image evaluation by a heart team must include transthoracic echocardiogram, transesophageal echocardiogram, and cardiac computed tomography angiography (CTA). CTA is used to determine access site (transapical, transseptal, or transatrial), transcatheter valve size, and landing zone. Though complications can occur (ie, valve embolization, bleeding, or vascular complications), this less invasive procedure has a reported success rate of 70% to 100% and is now increasingly used.

Anticoagulation Quality and Complications of using Vitamin K Antagonists in the Cardiac Surgery Outpatient Clinic

Introduction

In patients with mechanical prosthetic heart valves or atrial fibrillation requiring anticoagulation to prevent thromboembolic events, several factors influence adherence and anticoagulation complications.

Objective

To evaluate the factors that interfere with the quality and complications of anticoagulation with vitamin K antagonists.

Methods

A retrospective cohort study of 100 patients, in the period from 2011 to 2014, was performed. Anticoagulation conditions in the last year, regarding the presence of complications (embolisms/bleeding) and inadequate treatment were assessed: achievement of less than 8 annual prothrombin times and International Normalized Ratio outside therapeutic target in more than 40% of prothrombin times.

Results

There were 31 complications (22 minor bleeding without hospitalization and 9 major complications: 7 bleeding with hospitalization and two emboli); 70 were with International Normalized Ratio outside the target in more than 40% of the tests and 36 with insufficient number of prothrombin times. Socioeconomic factors, anticoagulant type and anticoagulation reason had no relationship with complications or with inadequate treatment. There were more complications in patients with longer duration of anticoagulation (P=0.001). Women had more International Normalized Ratio outside the target range (OR 2.61, CI:1.0-6.5; P=0.04). Patients with lower number of annual prothrombin times had longer times of anticoagulation (P=0.03), less annual consultations (P=0.02) and less dose adjustments (P=0.003). Patients with longer duration of anticoagulation have more complications (P=0.001).

Conclusion

There was a high rate of major complications and International Normalized Ratio was outside the goal. Less annual prothrombin times was related to longer duration of anticoagulation, less annual consultations and less dose adjustments. More major complications occurred in patients with longer duration of anticoagulation.

The mechanisms, diagnosis and management of mitral regurgitation in mitral valve prolapse and hypertrophic cardiomyopathy

Valvular disease is a frequent cardiac pathology leading to heart failure and, ultimately, death. Mitral regurgitation, defined as the inability of the two mitral leaflets to coapt, is a common valvular disease and a self sustained pathology. A better understanding of the mitral valve histological layers provides a better understanding of the leaflet and chordae changes in mitral valve prolapse. Mitral valve prolapse may occur in myxomatous degenerative abnormalities, connective tissue disorders or in sporadic isolated cases. It is the most common mitral abnormality of non-ischemic cause leading to severe surgery-requiring mitral regurgitation. In addition to standard echocardiographic investigations, newly implemented three-dimensional techniques are being used and they permit a better visualisation, from the so-called ‘surgical view’, and an improved evaluation of the mitral valve. Hypertrophic cardiomyopathy is the most frequent inherited myocardial disease caused by mutations in various genes encoding proteins of the cardiac sarcomere, leading to a marked left ventricular hypertrophy unexplained by other comorbidities. The pathological echocardiographic hallmarks of hypertrophic cardiomyopathy are left ventricular hypertrophy, left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve. The systolic anterior motion of the mitral valve contributes to the development of mitral regurgitation and further narrows the left ventricular outflow tract, leading to more severe symptomatology. Cardiac magnetic resonance imaging accurately measures the left ventricular mass, the degree of diastolic function and it may also be used to distinguish phenotypic variants. The clinical outcome of patients with these pathologies is mostly determined by the selected option of treatment. The purpose of surgical correction regarding mitral valve involvement is to restore valvular competence. Surgery has proven to be the only useful treatment in preventing heart failure, improving symptomatology and reducing mortality. Our approach wishes to enhance the understanding of the mitral valve’s involvement in hypertrophic cardiomyopathy and mitral valve prolapse from genetic, haemodynamic and clinical perspectives, as well as to present novelties in the grand field of treatment.

Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

BACKGROUND

Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence.

METHODS

Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves.

RESULTS

Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0).

CONCLUSIONS

Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring the anti-coagulation independent mechanical valve within reach.

A review of outcome following valve surgery for rheumatic heart disease in Australia

Background

Globally, rheumatic heart disease (RHD) remains an important cause of heart disease. In Australia it particularly affects younger Indigenous and older non-Indigenous Australians. Despite its impact there is limited understanding of the factors influencing outcome following surgery for RHD.

Methods

The Australian and New Zealand Society of Cardiac and Thoracic Surgeons Cardiac Surgery Database was analysed to assess outcomes following surgical procedures for RHD and non-RHD valvular disease. The association with demographics, co-morbidities, pre-operative status, valve(s) affected and operative procedure was evaluated.

Results

Outcome of 1384 RHD and 15843 non-RHD valve procedures was analysed. RHD patients had longer ventilation, experienced fewer strokes and had more readmissions to hospital and anticoagulant complications. Mortality following RHD surgery at 30 days was 3.1 % (95 % CI 2.2 – 4.3), 5 years 15.3 % (11.7 – 19.5) and 10 years 25.0 % (10.7 – 44.9). Mortality following non-RHD surgery at 30 days was 4.3 % (95 % CI 3.9 - 4.6), 5 years 17.6 % (16.4 - 18.9) and 10 years 39.4 % (33.0 - 46.1). Factors independently associated with poorer longer term survival following RHD surgery included older age (OR1.03/additional year, 95 % CI 1.01 – 1.05), concomitant diabetes (OR 1.7, 95 % CI 1.1 – 2.5) and chronic kidney disease (1.9, 1.2 – 2.9), longer invasive ventilation time (OR 1.7 if greater than median value, 1.1– 2.9) and prolonged stay in hospital (1.02/additional day, 1.01 – 1.03). Survival in Indigenous Australians was comparable to that seen in non-Indigenous Australians.

Conclusion

In a large prospective cohort study we have demonstrated survival following RHD valve surgery in Australia is comparable to earlier studies. Patients with diabetes and chronic kidney disease, were at particular risk of poorer long-term survival. Unlike earlier studies we did not find pre-existing atrial fibrillation, being an Indigenous Australian or the nature of the underlying valve lesion were independent predictors of survival.