A Case of Severe Aortic Stenosis after Aortic Valve Neocuspidization Using Autologous Pericardium (Ozaki Procedure)

Ectopic Calcification in Congenital Heart Surgery: A Material-Centric Review

The modern congenital heart surgeon has an array of materials available for cardiovascular repair. With advancements in the surgical outcomes for pediatric cardiac defects, choice of material has become increasingly dependent on late-term complications associated with each material. Calcification is a leading long-term complication and is increasing in prevalence with materials lasting longer in patients. Material calcification can impair functionality, lead to subsequent complications, and require additional interventions. A comprehensive literature review was conducted to investigate ectopic calcification of commonly used materials for congenital heart defect repair. Mechanisms of ectopic calcification among commonly used materials were investigated. Ectopic calcification is initiated by material-specific immunological reactions. Recent efforts have focused on developing new materials that are not prone to calcification. ePTFE was widely used in cardiovascular applications but still has reported instances of calcification in various situations, such as long-term use. Tissue engineering techniques have shown reduced calcification in reports. Calcification can occur in all conventional materials we reviewed and, in some cases, has led to life-threatening complications. Favorable outcomes have been reported with tissue-engineered materials, with the expectation of continued positive results in future reports. With an array of synthetic and biological materials now displaying acceptable surgical and short-term outcomes, there is a pressing need to review the long-term viability of these materials, especially considering improved patient survival to adulthood. Furthermore, developing new materials to mitigate calcification remains a promising avenue of research in this field.

Tissue requirements for the application of aortic valve neocuspidization - appropriate pericardium properties and homogeneity?

OBJECTIVE

Aortic valve neocuspidization (AVNeo) using autologous pericardium is a promising technique. Expected advantages are reduced immune response, appropriate biomechanics and lower treatment expenses. Nevertheless, autologous pericardium can be affected by patient's age and comorbidities. Usually, glutaraldehyde (GA) - fixed bovine pericardium is the basic material for aortic valve prostheses, easy available and carefully pre-examined in a standardized fabrication process. Aim of the study is the verification of autologous pericardial tissue homogeneity by analysing tissue thickness, biomechanics and extracellular matrix (ECM) composition.

METHODS

Segments of human GA-fixed pericardium selected by the surgeon based on visual criteria for cusp pre-cut and remaining after surgical AV replacement were investigated in comparison to bovine standard tissue treated equivalently. Pericardium sampling was performed at up to three positions of each sutured cusp for histological or biomechanical analysis, according to tissue availability.

RESULTS AND CONCLUSIONS

Human pericardia exhibited a higher heterogeneity in collagen content, density of vessel structures and elastic moduli. Thickness, vessel density and collagen and elastin content differed significantly between the species. In contrast, significant interindividual differences were detected in most properties investigated for human pericardial samples but only for tissue thickness in bovine tissues. Higher heterogeneity of human pericardium, differing vessel and collagen content compared to bovine state-of-the-art material might be detrimental for long term AV functionality or deterioration and have to be intensely investigated in patients follow up after autologous cusp replacement.

Ozaki procedure-re-construction of aortic valve leaflets using autologous pericardial tissue: a review

The Ozaki procedure has emerged as a valuable option for treating various aortic valve pathologies. This review article delves into the intricacies of this innovative surgical approach by exploring its adaptation to the complex anatomy and physiology of the aortic root. The diverse etiologies of aortic valve diseases, ranging from congenital anomalies to degenerative changes, make treatment selection a complex challenge. Aortic valve replacement has traditionally been the gold standard, but emerging evidence supports valve repair techniques, emphasizing the importance of preserving native tissue. Nevertheless, issues like lifelong anticoagulation with mechanical valves and patient-prosthetic mismatch remain. The Ozaki procedure offers a compelling alternative by utilizing autologous pericardium or a tissue substitute to construct new aortic valve leaflets. This technique, standardized by Dr. Ozaki in 2007, provides a customizable and adaptable solution. The article highlights the anatomy of the aortic root, emphasizing the critical role of the sinus of Valsalva and interleaflet triangles in maintaining proper valve function. The procedure's unique adaptation to aortic root dynamics allows for reduced mechanical stress during systole and diastole, mimicking the natural valve's behavior. Furthermore, Ozaki leaflets exhibit promising hemodynamics and reduced risks of complications, such as permanent pacemaker implantation and patient-prosthetic mismatch. The use of autologous pericardium in the Ozaki procedure presents advantages, including enhanced tissue strength, minimal immunogenicity, and reduced risk of immune-mediated calcification. These factors contribute to the longevity and resilience of the reconstructed valve. This comprehensive review aims to shed light on the procedure's intricacies, its alignment with aortic root anatomy and physiology, and its potential as a valuable tool in the armamentarium of aortic surgeons.

Aortic valve neocuspidization and its technical nuance

Aortic valve neocuspidization or Ozaki procedure represents an advanced surgical strategy for the management of patients with aortic valvulopathy. It has been shown to have clinical and hemodynamic outcomes that compare favorably with aortic valve replacement as it restores physiological aortic valve function and left ventricular remodeling. There are, however, a new set of issues including structural valve deterioration, leaflet tear/perforation, and need for reoperation. A keen understanding of the technical nuances involved with the Ozaki procedure may help in reducing the incidence of such adverse outcomes.