Hemolysis in Mechanical Bileaflet Prostheses: Experience With the Bicarbon Valve

Mechanical Hemolysis Complicating Transcatheter Interventions for Valvular Heart Disease: JACC State-of-the-Art Review

Mechanical intravascular hemolysis is frequently observed following procedures on heart valves and uncommonly observed in native valvular disease. In most cases, its severity is mild. Nevertheless, it can be clinically significant and even life threatening, requiring multiple blood transfusions and renal replacement therapy. This paper reviews the current knowledge on mechanical intravascular hemolysis in valvular disease, before and after correction, focusing on pathophysiology, approach to diagnosis, and impact of other hematological conditions on the resultant anemia. The importance of a multidisciplinary management is underscored. Laboratory data are provided about subclinical hemolysis that is commonly observed following the implantation of surgical and transcatheter valve prostheses and devices. Finally, clinical scenarios are reviewed and current medical and surgical treatments are discussed, including alternative options for inoperable patients.

Clinical mid-term outcomes of the Chinese-made CL-V bileaflet mechanical heart valve in Chinese patients

Background

The CL-V full-carbon bileaflet mechanical heart valve is a novel Chinese-made prosthetic valve. This study evaluated the mid-term outcomes of the CL-V bileaflet mechanical heart valve after implantation in Chinese patients.

Methods

This study retrospectively enrolled a total of 38 consecutive patients who underwent elective mechanical heart valve replacement (MHVR) with two different valve types from April 2004 and May 2010, including 18 patients with the CL-V bileaflet mechanical heart valve (44.4% male, mean age 47.4±6.2 years, mean body weight 64.7±11.9 kg) and 20 patients with the St. Jude mechanical heart valve (45.0% male, mean age 49.7±7.6 years, mean body weight 66.1±11.1 kg). All patients underwent follow-up clinical evaluations in the outpatient department at all-time points.

Results

No complications occurred during the mean 61.3 months follow-up time (range, 47–102 months). The cardiothoracic ratios (52.7%±4.5% vs. 50.1%±4.0%), left atrium diameter (46.5±7.6 vs. 44.8±9.3 mm), left ventricular diastolic diameter (47.6±4.9 vs. 48.2±8.5 mm) and left ventricular ejection fraction (65.4%±8.7% vs. 64.5%±8.0%) were not significantly different between the two groups (P>0.05). Transthoracic Doppler echocardiography showed that the hemodynamic indexes were not significantly different between the two groups at 1 year and 3 years (P>0.05). Furthermore, no significant differences were found between the two groups in hemocompatibility indexes at both 6 months and 3 years postoperatively (P>0.05).

Conclusions

The mid-term follow-up results of the CL-V bileaflet mechanical heart valve were similar to those of the St. Jude Medical heart valve, which showed stable hemodynamics and good blood compatibility. Chinese-made CL-V bileaflet mechanical heart valves can be a substitute for St. Jude Medical heart valves, and can be widely used in cardiac surgery.

Trial registration

Chinese Clinical Trial Registry ChiCTR2000034158.

Intravascular haemolysis after transcatheter aortic valve implantation with self-expandable prosthesis: incidence, severity, and impact on long-term mortality

We aimed to determine the incidence, severity, and long-term impact of intravascular haemolysis after self-expanding transcatheter aortic valve implantation (TAVI). We believe this should be evaluated before extending the indications of TAVI to younger low-risk patients. Prospective, academic, single centre study of 94 consecutive patients treated with supra-annular self-expandable TAVI prosthesis between April 2009 and January 2014. Haemolysis at 1-year post-TAVI was defined per the published criteria based on levels of haemoglobin, reticulocyte and schistocyte count, lactate dehydrogenase (LDH), and haptoglobin. All patients had long-term clinical follow-up (6 years). The incidence of haemolysis at 1-year follow-up varied between 9% and 28%, based on different haemolysis definitions. Haemolysis was mild in all cases, no patient had markedly increased LDH levels. The presence of moderate/severe paravalvular aortic regurgitation was associated with haemolysis (7.7% vs. 23.1%, P = 0.044) and aortic valve area post-TAVI did not differ between groups with or without haemolysis (1.01 vs. 0.92 cm²/m², P = 0.23) (definition including schistocyte count). The presence of haemolysis did not have any impact on patient prognosis after 6 years with log-rank test P = 0.80. Intravascular haemolysis after TAVI with self-expandable prosthesis is present in 9–28% of patients depending on the definition of haemolysis. The presence of haemolysis is associated with moderate/severe paravalvular aortic regurgitation but not with post-TAVI aortic valve area. Haemolysis is mild with no impact on prognosis.

Nineteen Years of Single Institute Experiences with Sorin Bicarbon Prosthesis

Purpose: We want to share our experience of Sorin Bicarbon prosthesis (SBP) after 19 years follow-up.

Methods: Retrospective study of 1377 patients who had replaced with SBP from May 1998 to December 2008 at Ho Chi Minh Heart Institute, Viet Nam.

Results: Male patients was 42%, mean age was 40.2 ± 11.8 years. Atrial fibrillation was 43.5%. The main cause of valvular disease was rheumatic fever (89.8%). Isolated mitral valve replacement (MVR): 54% (744), isolated aortic valve replacement (AVR): 18% (247), double valve replacement (DVR): 26% (359), and 27 AVR plus mitral repair. 30-day mortality for all was 1.5%. Mean time of follow-up was 153 ± 53.1 months with total follow-up time was 17563 patients-years. 2.5% lost of follow-up. Late death was 77 cases. Redo for all causes was 59 cases. 19 years survival was 88.8 ± 1.8%. 19 years freedom of redo was 76.4 ± 4.7%. Linearized rate of all valve thrombosis, embolism, severe bleeding, endocarditis, and pannus were 0.31%, 0.28%, 0.267%, 0.068%, and 0.165% patient-years, respectively.

Conclusions: SBP had shown very good results in long term and still have a reliable mechanical valve.

Frequency and Significance of Intravascular Hemolysis Before and After Transcatheter Aortic Valve Implantation in Patients With Severe Aortic Stenosis

Intravascular hemolysis (IVH) has been identified in patients with surgical prosthetic valves, but few have been reported after transcatheter aortic valve implantation (TAVI). We conducted a prospective analysis of 64 TAVI patients. The hemolysis profiles were collected at baseline and 6 months after TAVI. The echocardiography was performed at baseline and 6 months after TAVI. There are 14 patients (21.9%) with IVH before and 24(37.5%) after TAVI. The serum haptoglobin values before and 6 months after TAVI are 126.7 ± 75.1 vs 86.3 ± 57.1 mg/dl (p < 0.001). More ≥moderate paravalvular leakage (PVL) (50% vs 7.5%, p < 0.001), bicuspid aortic valve (BAV) (33.3% vs 5.0%, p = 0.004), use of 23 mm prosthesis (29.2% vs 7.5%, p = 0.03), higher residual valvular pressure gradient (17.9 ± 6.8 mm Hg vs 14.7 ± 5.7 mm Hg, p = 0.05), and lower effective orifice area index (1.05 ± 0.21 vs 1.21 ± 0.29, p = 0.03) were observed in patients with post-TAVI IVH. On multivariate regression analysis, BAV and ≥moderate PVL are independently related to post-TAVI IVH. With log-rank test, 1-year rates of readmission due to cardiovascular cause were significantly higher in patients with post-TAVI IVH (odds ratio 4.5; 95% confidence interval 1.3 to 15.6; p = 0.02), after adjusting age and gender. In conclusion, ≥moderate PVL and BAV are predictors of post-TAVI IVH, which is associated with increased cardiovascular readmission in 1-year follow-up.

Late subclinical hemolysis and long-term outcomes after aortic valve replacement with On-X mechanical prostheses - a preliminary single-center report

Introduction

Aortic valve replacement (AVR) with a mechanical prosthesis is not free from late complications.

Aim

To evaluate the prevalence of subclinical hemolysis after AVR with On-X prostheses and assess its impact on long-term outcomes.

Material and methods

The prospective study included 84 consecutive patients aged 58.3 ±10.3 years who underwent AVR. They were retrospectively split into group H (n = 12; 14.3%) with prosthesis-related subclinical hemolysis and a control group (C; n = 72; 85.7%). All operations were performed via median sternotomy using cardio-pulmonary bypass. At the end of follow-up, echocardiography was carried out and blood samples for morphology and biochemistry (lactate dehydrogenase (LDH), bilirubin, haptoglobin) were taken.

Results

The rate of subclinical hemolysis in patients with properly working prostheses was 14.3% and it was the highest (33.3%) for the smallest valves. Although an improvement in functional status was noted in both groups, it was less evident in group H than in group C (p = 0.007). At the end of follow-up, 97.2% in group C and 75.0% in group H were found in NYHA classes I and II. Patients in group H had significantly lower hemoglobin, hematocrit, and haptoglobin and higher LDH activity than group C subjects. In group H, systolic gradients of On-X valves were higher whereas effective orifice area was smaller than in group C.

Conclusions

Our study proved that prosthesis-induced subclinical hemolysis is seen even after implantation of the latest generation mechanical prostheses, particularly of small diameter, and its degree may impact late outcome.

Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve

Background

Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.

Results

An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.

Conclusions

We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12938-017-0314-2) contains supplementary material, which is available to authorized users.

Incidence and risk factors of hemolysis after transcatheter aortic valve implantation with a balloon-expandable valve

There are currently no data evaluating the hematologic and biocompatibility profile of transcatheter aortic valves in vivo. We evaluated the incidence, predictive factors, and clinical consequences associated with hemolysis post-transcatheter aortic valve implantation (TAVI). A total of 122 patients who underwent TAVI with a balloon-expandable valve were included. Baseline blood sampling and echocardiography, followed by early post-TAVI echocardiography and repeat blood sampling, at 6 to 12 months post-TAVI were performed. Hemolysis post-TAVI was defined according to the established criteria. The incidence of hemolysis post-TAVI was 14.8% yet no patient experienced severe hemolytic anemia requiring transfusion. Compared with the nonhemolysis group, those with hemolysis demonstrated significant reductions in hemoglobin (p = 0.012), were more frequently women (67% vs 34%, p = 0.016), and had a higher incidence of post-TAVI severe prosthesis-patient mismatch (PPM) (44% vs 17%, p = 0.026). The rate of mild or more prosthetic valve regurgitation did not significantly differ between those patients with and without hemolysis (56% vs 37%, p = 0.44). Wall shear rate (WSR) and energy loss index (ELI), both indirect measures of shear stress, were higher (p = 0.039) and lower (p = 0.004), respectively, in those patients with hemolysis. Increasing PPM severity was also associated with significant stepwise WSR increments and ELI decrements (p <0.01 for both). In conclusion, subclinical hemolysis occurred in 15% of patients following TAVI. Although prosthetic valve regurgitation had no impact on hemolysis, a novel association between PPM and hemolysis was found, likely driven by higher shear stress as determined by WSR and ELI. These hematologic and biomechanical findings may have long-term clinical implications and could affect future transcatheter aortic valve design.

Examining and mitigating acellular hemoglobin vasoactivity

SIGNIFICANCE

There has been a striking advancement in our understanding of red cell substitutes over the past decade. Although regulatory oversight has influenced many aspects of product development in this period, those who have approached the demonstration of efficacy of red cell substitutes have failed to understand their implication at the level of the microcirculation, where blood interacts closely with tissue.

RECENT ADVANCES

The understanding of the adverse effects of acellular hemoglobin (Hb)-based oxygen carriers (HBOCs) has fortunately expanded from Hb-induced renal toxicity to a more complete list of biochemical mechanism. In addition, various unexpected adverse reactions were seen in early clinical studies. The effects of the presence of acellular Hb in plasma are relatively unique because of the convergence of mechanical and biochemical natures.

CRITICAL ISSUES

Controlling the variables using genetic engineering and chemical modification to change specific characteristics of the Hb molecule may allow for solving the complex multivariate problems of acellular Hb vasoactivity. HBOCs may never be rendered free of negative effects; however, quantifying the nature and extent of microvascular complications establishes a platform for designing new ameliorative therapies.

FUTURE DIRECTIONS

It is time to leave behind the study of vasoactivity and toxicity based on bench-top measurements of biochemical changes and those based solely on systemic parameters in vivo, and move to a more holistic analysis of the mechanisms creating the problems, complemented with meaningful studies of efficacy.

Worsening of the clinical-hematological picture in a patient with a rare PK-LR compound heterozygosis after mitral replacement

We report a case of a patient affected by compound heterozygosis for two PK-LR gene mutations: p.R486W (c.1456C>T) and p.M403I (c.1209G>A). Our patient suffered from an initial moderate hemolytic anemia which subsequently evolved into a severe form after mitral prosthetic valve replacement for valve regurgitation. Thereafter, the clinical features evolved into a worsening of anemia, heart failure and pulmonary hypertension, in the absence of valve dysfunction. This clinical picture improved only after an intensive transfusion regimen. This case highlights aspects concerning the intricate balance between the risks and benefits of a mechanical prosthetic valve implant in PK-deficient patients.

Clinical experience with the Bicarbon heart valve prosthesis

Bacground

We have previously reported mid-term results of a study, which ended in January 2000, on the Bicarbon valve. The study concluded that the valve showed excellent clinical results, associated with a low incidence of valve-related complications. In the present study, the same patients were prospectively followed for an additional 5 years.

Methods

Forty-four patients had aortic valve replacement (AVR), 48 had mitral valve replacement (MVR), and 13 had both aortic and mitral valve replacement (DVR). The mean age of the 105 patients was 61.2 ± 11.3 years. The mean follow-up was 6.1 ± 1.9 years with a cumulative follow-up of 616 patient-years.

Results

There were 5 early deaths (4.7%: 4 in the AVR group and 1 in the MVR group) and 21 late deaths (3.4%/patient-year: 5 valve related deaths and 16 valve unrelated deaths). Survival at 8 years was 75.2 ± 7.0% in the AVR group, 76.6 ± 6.2% in the MVR group, and 55.4 ± 16.1% in the DVR group. The linearized incidence of thrombo-embolic complications, hemorrhagic complications, and paravalvular leaks in all patients was 0.65 ± 1.48%, 0.81 ± 1.69%, and 0.16 ± 0.54%/patient-year respectively. No other complications were observed.

Conclusion

The Bicarbon prosthetic heart valve has shown excellent long-term clinical results, associated with a low incidence of valve-related complications.