A morphologic study of Carpentier-Edwards pericardial xenografts in the mitral position exhibiting primary tissue failure in adults in comparison with Ionescu-Shiley pericardial xenografts

A case of aortic valve leaflet tear and perforations after neocuspidization

Although aortic valve (AV) replacement is a curative procedure for severe aortic stenosis, prosthetic heart valves have many disadvantages and cause serious complications. A new promising surgical procedure—aortic valve neocuspidization (AVNeo)—has recently been developed; it is an original method of AV reconstruction with autologous pericardium. It has been reported to yield excellent medium‐term results with respect to durability and complications. Herein, we encountered a first case of AV leaflet tear and perforations 27 months after AVNeo using autologous pericardium. AV leaflet tear or perforation is well recognized as a long‐term serious complication of pericardial xenografts. Interestingly, however, AVNeo caused early structural valve deterioration in the current case. In the present case, an eccentric aortic regurgitation jet observed on colour flow imaging led us to reach the correct diagnosis. Finally, the patient showed complete recovery with redo AV replacement. This case highlights the importance of understanding the potential pitfalls of this new surgical technique and that of colour Doppler echocardiography in reaching a definite diagnosis.

Simulation of long-term fatigue damage in bioprosthetic heart valves: effects of leaflet and stent elastic properties

One of the major failure modes of bioprosthetic heart valves (BHVs) is noncalcific structural deterioration due to fatigue of the tissue leaflets; yet, the mechanisms of fatigue are not well understood. BHV durability is primarily assessed based on visual inspection of the leaflets following accelerated wear testing. In this study, we developed a computational framework to simulate BHV leaflet fatigue, which is both efficient and quantitative, making it an attractive alternative to traditional accelerated wear testing. We utilize a phenomenological soft tissue fatigue damage model developed previously to describe the stress softening and permanent set of the glutaraldehyde-treated bovine pericardium leaflets in BHVs subjected to cyclic loading. A parametric study was conducted to determine the effects of altered leaflet and stent elastic properties on the fatigue of the leaflets. The simulation results show that heterogeneity of the leaflet elastic properties, poor leaflet coaptation, and little stent-tip deflection may accelerate leaflet fatigue, which agrees with clinical findings. Therefore, the developed framework may be an invaluable tool for evaluating leaflet durability in new tissue valve designs, including traditional BHVs as well as new transcatheter valves.

Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

Prosthetic heart valves are commonly used in the treatment of valvular heart disease. Mechanical valves are more durable than the bioprosthetic valves; however, the need for long-term anticoagulant therapy renders them unsuitable for some patient groups. In this paper we discuss the different types and models of bioprosthesis, and in particular, pericardial bioprosthesis. We also discuss the preimplantation preparation processes, as well as their postimplantation changes and modes of failure.

Stentless aortic valve replacement: an update

Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Optimizing hemodynamics to prevent patient–prosthetic mismatch and improve durability, stentless bioprostheses use was revived in the early 1990s. The purpose of this review is to provide a current overview of stentless valves in the aortic position. Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement (AVR), though stentless AVR required longer cross-clamp and cardiopulmonary bypass time. Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular (LV) mass regression compared with stented AVR. However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier–Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Freedom from reoperation at 12 years in Toronto stentless porcine valves ranged from 69% to 75%, which is much lower than for Carpentier–Edwards Perimount valves. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O’Brien valves also have shorter durability compared with stent valves. Actuarial freedom from reoperation was 44% at 10 years. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts. There was no level I or IIa evidence of more effective orifice area, mean pressure gradient, LV mass regression, surgical risk, durability, and late outcomes in stentless bioprostheses. There is no general recommendation to prefer stentless bioprostheses in all patients. For new-generation pericardial stentless valves, follow-up over 15 years is necessary to compare the excellent results of stented valves such as the Carpentier–Edwards Perimount and Hancock II valves.

A case of Carpentier-Edwards pericardial bioprosthesis in mitral position explanted 22 years after implantation

A case of Carpentier-Edwards PERIMOUNT (CEP) mitral pericardial bioprosthesis explanted 22 years after the valve replacement is reported. This patient underwent the previous replacement at the age of 50. The extracted bioprosthesis showed three rigid leaflets, one of which had a tear causing severe mitral regurgitation. The X-ray demonstrated calcification of varied extent among these leaflets, ranging from none to severe. When leaflet calcification is suppressed, perhaps the lifespan of a CEP valve can be prolonged more than previously expected. When a literature search was conducted, this case was found to represent the longest reported interval from the implantation of a CEP valve in the mitral position to the explantation as a result of severe mitral regurgitation caused by structural valve deterioration (SVD).

Beginning and development of surgery for acquired valvular heart disease in Japan

The initiation and development of surgery for acquired valvular heart disease in Japan was reviewed. The first series of attempts at closed valvular surgery were performed in 1951-1952 by collaboration between the brothers Tohru and Shigeru Sakakibara in patients with pulmonary or mitral stenosis. During the popularization of closed valvular surgery, open heart surgery under direct vision was successfully performed by Shigeru Sakakibara with cooling of the body in 1954 and by using cardiopulmonary bypass (CPB) in 1956. With the development of CPB and artificial heart valves, closed valvular heart surgery was replaced by open surgery, which expanded rapidly during the 1960s and 1970s. Along with the serial introduction and improvement of mechanical vales thereafter, bioprosthetic valves were also introduced and were adopted for certain patients. Use of bioprosthetic valves in the aortic position exceeded 50% in 2005, along with the increase of elderly patients. Although trials of mitral valve plasty for mitral regurgitation were first done during the 1950s to 1960s in Japan, interest in valve plasty only increased during the late 1970s. Considering the patient's quality of life and the long-term results, mitral valve plasty became the major procedure (exceeding valve replacement) from 2004. In 2002, the Guideline for Surgical and Interventional Treatment of Valvular Heart Disease was published by a joint committee of the relevant academic societies, and it has made an important contribution to improving surgical outcomes.

A case of 24 years longevity of an Ionescu-Shiley bioprosthesis in the mitral position

Valve dysfunction, attributed to primary tissue failure several years after implantation of Ionescu-Shiley bioprostheses, has led to re-operation in most cases. We report a rare case of this bioprosthesis showing stenosis and regurgitation after implantation in the mitral position 24 years previously. No cusp tears, but severe calcification and well-grown neointima over the Dacron cloth of the inner surface were observed. This may explain how the valve functioned for such a long period of time. We replaced it with a Carpentier-Edwards pericardial bioprosthesis.

Factors influencing calcification of cardiac bioprostheses in adolescent sheep

OBJECTIVE

We determined the possible effects of age, antimineralization treatments, circulatory implant conditions, prosthesis design, and valve-related structural aspects on valve calcification in adolescent sheep.

METHODS

Calcium content was measured by means of atomic absorption spectrometry in bioprostheses implanted in 120 sheep (age <1 year) for a period of 3 or 6 months.

RESULTS

Bioprostheses calcified significantly in adolescent sheep, but the extent of calcification was multifactorial. Multivariate analysis of the calcium content reveals that age, mitral or pulmonary implant position, prosthesis design (stented or stentless), structure (porcine or pericardial, wall portion or cusp), and antimineralization treatment are independent factors influencing calcification; implant duration beyond 3 months was not. In juvenile sheep (age 5 months) the wall portion, as well as the cusps of the prosthesis, calcified significantly more than in adolescent sheep (age 11 months). Irrespective of age, the cusps of valves implanted in the mitral position calcified more than those in the pulmonary position. The wall portion of stentless valves calcified more than that of stented valves, and pericardial valves calcified less than porcine valves. The surfactant (Tween 80, No-React, and alpha-amino-oleic acid) and alcohol (ethanol and octanediol) treatment significantly reduced cusp calcification; sodium dodecylsulfate did not. None of the anticalcification treatments was able to prevent wall calcification in stentless porcine valves.

CONCLUSION

These findings suggest that tissue valve calcification is determined by many independent factors, which can be identified by using adolescent sheep as a preclinical in vivo model.

Durability and outcome of aortic valve replacement with mitral valve repair versus double valve replacement

BACKGROUND

The purpose of this study was to evaluate morbidity and mortality after double valve replacement (DVR) and aortic valve replacement with mitral valve repair (AVR + MVP).

METHODS

From 1977 to 2000, 379 patients underwent DVR (n = 299) or AVR + MVP (n = 80). Actuarial survival and freedom from reoperation were determined by the Kaplan-Meier method. Potential predictors of mortality and reoperation were entered into a Cox multiple regression model. Propensity score was introduced for the multivariable regression modeling for adjustment of a selection bias.

RESULTS

Survival 15 years after surgery was similar between the groups (DVR, 81% +/- 3%; AVR + MVP, 79% +/- 7%; p = 0.44). Freedom from thromboembolic event at 15 years was similar between the groups (p = 0.25). Freedom from mitral valve reoperation at 15 years was significantly better for the DVR group (54% +/- 5%) as compared with the AVR + MVP group (15% +/- 6%; p = 0.0006), primarily due to progression of mitral valve pathology and early structural deterioration of bioprosthetic aortic valve used for patients with AVR + MVP. After AVR + MVP, freedom from mitral reoperation at 15 years was 63% +/- 16% for nonrheumatic heart diseases, and 5% +/- 5% for rheumatic disease (p = 0.04).

CONCLUSIONS

Although both DVR and AVR + MVP provided excellent survival, DVR with mechanical valves should be the procedure of choice for the majority of patients because of lower incidence of valve failure and similar rate of thromboembolic complications compared with AVR + MVP. MVP should not be performed in patients with rheumatic disease because of higher incidence of late failure.