Twenty-year single-center experience with the medtronic open pivot mechanical heart valve

Propensity matched long-term analysis of mechanical versus stentless aortic valve replacement in the younger patient

OBJECTIVES

The choice of prosthesis for aortic valve replacement (AVR) in younger patients remains controversial. Stentless AVR was introduced 3 decades ago, with the aim of better haemodynamics and durability than stented xenografts. The objective of this analysis was to compare the long-term outcomes to mechanical prostheses in younger patients (age ≤60 years).

METHODS

All adult patients who underwent AVR due to aortic valve stenosis and/or insufficiency between 1993 and 2002 were identified. After the exclusion of patients with congenital heart defects, aortic dissections and Ross-procedures, 158 patients with stentless valves and 226 patients with bi-leaflet mechanical valves were finally included in this analysis. Sixty-six patient pairs could be included in a propensity matched analysis. Mortality and morbidity including stroke, bleeding, endocarditis and reoperation were analysed.

RESULTS

Group baseline characteristics and operative data did not differ significantly after propensity matching. Hospital mortality was 0.0% in the stentless and 1.5% in the mechanical group. Total patient years/median follow-up was 2029.1/15.4 years (completeness: 100.0%, range: 0-25 years). After 20 years, actuarial survival was 47.0 ± 6.4% in the stentless and 53.3 ± 6.6% in mechanical group (P = 0.69). Bleeding, endocarditis and stroke occurred rarely and did not differ significantly between groups. After 20 years, actuarial overall freedom-from-reoperation was 45.1 ± 8.2% in the stentless group and 90.4 ± 4.1% in the mechanical group (P < 0.001). Hospital mortality while reoperation was 7.4% in the stentless group and 0% in the mechanical group (P = 1.0).

CONCLUSIONS

Long-term morbidity and mortality of stentless and mechanical aortic valves were statistically not different besides a significantly higher reoperation rate after stentless AVR combined with a probably higher risk of in-hospital mortality. Thus, mechanical AVR should remain the procedure of choice in younger patients.

Long-Term Clinical Outcomes of the On-X Mechanical Prosthetic Valve in the Aortic or Mitral Position - A Single-Center Experience of up to 20 Years' Follow up

BACKGROUND

This study evaluated the long-term outcomes for up to 20 years after On-X mechanical valve implantation in the left side of the heart.Methods and Results:Between 1999 and 2015, 861 patients (mean age=51.6±10.9 years) who underwent prosthetic valve replacement using the On-X valve in the aortic or mitral position were enrolled (aortic=344, mitral=325, double=192). The mean clinical follow-up duration was 10.5±5.3 (median 10.9) years. Operative mortality occurred in 26 patients (3.0%), and linearized late cardiac mortality was 0.9%/patient-year without an intergroup difference. Linearized thromboembolism, bleeding, prosthetic valve endocarditis, non-structural valve deterioration (NSVD), and reoperation rates were 0.8%/patient-year, 0.6%/patient-year, 0.2%/patient-year, 0.5%/patient-year, and 0.5%/patient-year, respectively. Prosthetic valve endocarditis was more frequent after double valve replacement than after aortic or mitral valve replacement (P=0.008 and 0.005, respectively). NSVD and reoperation rates were significantly lower aortic valve replacement than after mitral or double valve replacement (P=0.001 and 0.002, P=0.001 and <0.001, respectively). Valve replacement in the mitral position was the only risk factor for NSVD (hazard ratio [95% confidence interval]=5.247 [1.608-17.116], P=0.006).

CONCLUSIONS

On-X valve implantation in the left side heart had favorable clinical outcomes with acceptable early and late mortality and a low incidence of prosthetic valve-related complications. Particularly in the aortic position, the On-X valve had better long-term non-structural durability.

Diamond Anniversary of Mechanical Cardiac Valve Prostheses: A Tale of Cages, Balls, and Discs

This year marks the 60th anniversary of the first aortic and mitral valve replacements using mechanical artificial prosthesis. The first caged-ball devices represented a milestone in cardiac surgery and in the treatment of valvular disease. The following decades witnessed a great evolution in mechanical valve technology providing, through frustrating complications and stimulating successes, more reliable models to be safely used in the clinical setting. This review pays tribute to pioneers of this field who made currently available the most advanced models of mechanical prostheses with extended records of durability and performance, to be used as reliable alternatives to biological devices.

Customizing the Shape and Microenvironment Biochemistry of Biocompatible Macroscopic Plant-Derived Cellulose Scaffolds

Plant-derived cellulose scaffolds constitute a highly viable and interesting biomaterial. They retain a high flexibility in shape and structure, present the ability to tune surface biochemistry, display a high degree of biocompatibility, exhibit vascularization, and are widely available and easily produced. What is also immediately clear is that pre-existing cellulose structures in plants can also provide candidates for specific tissue engineering applications. Here, we report a new preparation and fabrication approach for producing large scale scaffolds with customizable macroscopic structures that support cell attachment and invasion both in vitro and in vivo. This new fabrication method significantly improves cell attachment compared to that in our previous work. Moreover, the materials remain highly biocompatible and retain vascularization properties in vivo. We present proof-of-concept studies that demonstrate how hydrogels can be temporarily or permanently cast onto the macroscopic scaffolds to create composite plant-derived cellulose biomaterials. This inverse molding approach allows us to provide temporary or permanent biochemical cues to invading cells in vitro. The development of a new-generation of rapidly and efficiently produced composite plant-derived biomaterials provides an important proof that such biomaterials have the potential for numerous applications in tissue engineering.

Effects of heart valve prostheses on phase contrast flow measurements in Cardiovascular Magnetic Resonance - a phantom study

BACKGROUND

Cardiovascular Magnetic Resonance is often used to evaluate patients after heart valve replacement. This study systematically analyses the influence of heart valve prostheses on phase contrast measurements in a phantom trial.

METHODS

Two biological and one mechanical aortic valve prostheses were integrated in a flow phantom. B0 maps and phase contrast measurements were acquired at a 1.5 T MR scanner using conventional gradient-echo sequences in predefined distances to the prostheses. Results were compared to measurements with a synthetic metal-free aortic valve.

RESULTS

The flow results at the level of the prosthesis differed significantly from the reference flow acquired before the level of the prosthesis. The maximum flow miscalculation was 154 ml/s for one of the biological prostheses and 140 ml/s for the mechanical prosthesis. Measurements with the synthetic aortic valve did not show significant deviations. Flow values measured approximately 20 mm distal to the level of the prosthesis agreed with the reference flow for all tested all prostheses.

CONCLUSIONS

The tested heart valve prostheses lead to a significant deviation of the measured flow rates compared to a reference. A distance of 20 mm was effective in our setting to avoid this influence.

Bio-functionalization of biomedical metals

Bio-functionalization means to endow biomaterials with bio-functions so as to make the materials or devices more suitable for biomedical applications. Traditionally, because of the excellent mechanical properties, the biomedical metals have been widely used in clinic. However, the utilized functions are basically supporting or fixation especially for the implantable devices. Nowadays, some new functions, including bioactivity, anti-tumor, anti-microbial, and so on, are introduced to biomedical metals. To realize those bio-functions on the metallic biomedical materials, surface modification is the most commonly used method. Surface modification, including physical and chemical methods, is an effective way to alter the surface morphology and composition of biomaterials. It can endow the biomedical metals with new surface properties while still retain the good mechanical properties of the bulk material. Having analyzed the ways of realizing the bio-functionalization, this article briefly summarized the bio-functionalization concepts of six hot spots in this field. They are bioactivity, bony tissue inducing, anti-microbial, anti-tumor, anticoagulation, and drug loading functions.

Valve-related complications after mechanical heart valve implantation

The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7-3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4-1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

Emerging trends in heart valve engineering: Part III. Novel technologies for mitral valve repair and replacement

In this portion of an extensive review of heart valve engineering, we focus on the current and emerging technologies and techniques to repair or replace the mitral valve. We begin with a discussion of the currently available mechanical and bioprosthetic mitral valves followed by the rationale and limitations of current surgical mitral annuloplasty methods; a discussion of the technique of neo-chordae fabrication and implantation; a review the procedures and clinical results for catheter-based mitral leaflet repair; a highlight of the motivation for and limitations of catheter-based annular reduction therapies; and introduce the early generation devices for catheter-based mitral valve replacement.