Cusp Height Research Articles

Resource partitioning among late Pleistocene herbivores of Natural Trap Cave, Wyoming

Natural Trap Cave (NTC) preserves abundant late Pleistocene herbivore remains including equids (Equus and Haringtonhippus) and the sheep Ovis. The NTC equid sample contains a minimum of two taxa, while other large herbivore genera are represented by single species. In modern communities, sympatric herbivores partition resources by feeding on different plants or different plant parts. Previous dental isotopic studies indicated that most NTC herbivores consumed C3 plants, including grasses. To test the hypothesis that resource partitioning occurred among grass-feeders at NTC, we collected mesowear data from both equids as well as Ovis, using samples collected by teams from the University of Kansas between 1974 and 1985.Assessed on upper cheek teeth, mesowear derives from either attritional (tooth on tooth) or abrasional (tooth on abrasive food) wear. The paracone and metacone were examined on each specimen to determine cusp shape (sharp, rounded, or blunt) and occlusal relief (high or low). A diet of non-abrasive material yields high and sharp cusps and one of heavily abrasive materials results in low and blunt cusps, while rounded cusps indicate intermediate levels of abrasion. A large sample (N = 143) of equid teeth included two morphs. A smaller sample (N = 10) of Ovis teeth provided comparison with the equid teeth. Data collected consisted of individual variables of cusp heights and shape, as well as stages of mesowear combining both variables. Upper adult M1/2s and P4s were used.Results from the equid sample revealed that 8% exhibited high and sharp/rounded cusps, indicating little dietary abrasion; 58% had low and rounded cusps; and 34% had low and blunt cusps. The latter grouping is evidence for a highly abrasive diet. In the sample of Ovis, the results are strikingly different: 40% had high and sharp cusps and 60% had high and rounded cusps. Even though mountain sheep are often interpreted to be grass feeders, their mesowear suggests they did not eat an abrasive diet at NTC.The distribution of mesowear scores among the equid fossils conforms with an interpretation of two equid taxa at NTC, as well as supporting our hypothesis that these taxa partitioned grass resources. The very different nature of the mesowear signature seen in Ovis, compared to the equid fossils, also supports our hypothesis that these grass-feeders either consumed a more mixed or browse-dominated diet with different overall levels of abrasion, or else ate different parts of grass plants. As observed in the Serengeti grazing succession, we propose that equids may have moved through the area first, consuming taller, older, more abrasive parts of grass plants, followed by mountain sheep eating softer, younger plants.

Advancing towards sustainability in liquid crystal display 3D printing via adaptive slicing

Liquid crystal display 3D printing is rapidly spreading due to the low cost of equipment and the high accuracy of manufactured parts. Particularly, this process is widespread in dental and medical fields to realise customised healthcare solutions. This study presents a parametric cradle-to-gate life cycle assessment of the liquid crystal display 3D printing process based on the part mass and building time. Specifically, the endpoint environmental impact indicators are calculated using the Recipe 2016 v 1.1 methodology with a hierarchist strategy. Also, a cost model of the process is included to assess the economic aspects of the production. This model comprises the cost of material, energy, consumables and equipment. An adaptive slicing strategy for liquid crystal display 3D printing is proposed. This algorithm starts slicing the model with the minimum layer height, then proceeds by collapsing adjacent layers so as to preserve a certain maximum imposed cusp height. The main aim of this research is to investigate the potential sustainability advantages of this strategy over traditional slicing. To this end, the life cycle assessment and cost models of the process are applied to two benchmark parts, namely a patient-specific dental model and an adapter designed to convert snorkel masks in respirators to face the COVID 19 emergency. The results demonstrate that the adaptive slicing strategy effect on part accuracy is negligible. In contrast, this method significantly increases the sustainability of the process by decreasing the building time. Specifically, the impacts on human health and resource depletion are reduced by up to 48.4% and 51.3%, respectively. Moreover, a significant reduction of the cost per part is observed. Finally, the increased productivity determines social benefits, being the produced parts intended for healthcare purposes. Therefore, the use of adaptive slicing instead of traditional strategies is strongly encouraged to advance towards the sustainability of this technology.

Abstract 11886: Total Root Remodeling by Sleeve Technique for Severe Aortic Regurgitation in Patient With Mild or Moderate Root Dilatation

Introduction: Cusp repair in combination with root repair is a central strategy for aortic regurgitation (AR). However, aortic root replacement in patient without significant root dilatation is controversial. Hypothesis: Sleeve procedure can be an alternative to root replacement in such clinical settings. Methods: 27 tricuspid aortic valve patients (Body surface area: 1.64±0.16 m2) without significant root dilatation who underwent aortic valve repair with Sleeve procedure during January, 2017-April 2020 were studied. Of the 81 cusps, 34 cusps underwent central plication. Neo-chord technique was prophylactically applied in 12 cusps to prevent future leaflet prolapse. Selected Valsalva graft size was 26.1±1.4 mm. Pre- and post-operative diastolic valve geometry was evaluated by 3D cardiac computed tomography. Results: Geometric change in aortic valve by Sleeve is summarized in the Table. Postoperative increase in commissure height was noted and effective height of non-plicated cusp kept more than 8.5 mm in average postoperatively despite of the nearly 10 mm reduction in STJ diameter. There was no recurrence of AR more than grade II in one year follow-up. Conclusions: Preserved or increased commissure height by Sleeve procedure may contribute to sufficient cusp coaptation with preventing an iatrogenic cusp prolapse. Because of the external covering with the graft, neo-chord technique could be stably performed under Sleeve procedure. Sleeve procedure offers valve-sparing and total root remodeling without root replacement/coronary reconstruction in repairing AR, which may be beneficial for patients with mild or moderate root dilatation.

Tool Path Generation for Five-Axis Controlled Machining of Free-Form Surfaces Using a Barrel Tool Considering Continuity of Tool Postures

This study aims to improve the efficiency of free-form surface machining using a five-axis controlled machine tool and a barrel tool. The barrel tool has cutting edges with curvatures smaller than its radius; thus, its pick feed width is larger than that of a conventional ball end mill with the same tool radius. Therefore, the machining efficiency can be improved. Barrel tools can be effectively utilized in a five-axis controlled machine tool. When five-axis controlled machining, tool interference may occur, which should be avoided during actual machine operation. Additionally, a sudden change in tool posture adversely affects the quality of the machined surface. This paper proposes a method to obtain the cutting points that render cusp heights below the target value. A method for generating an interference-free tool path, in which the tool posture changes continuously, is also proposed. The usefulness of the developed methods was confirmed through machining simulations.

Volumetric adaptive slicing of manifold mesh for rapid prototyping based on relative volume error

PurposeCompared with cusp height and area deviation ratio, volume error (VE) caused by the layer height could represent the stair-case effect more comprehensively. The proposed relative volume error (RVE)-based adaptive slicing method takes VE rather than cusp height as slicing criteria, which can improve part surface quality for functionalized additive manufacturing.Design/methodology/approachThis paper proposes a volumetric adaptive slicing method of manifold mesh for rapid prototyping based on RVE. The pre-height sequences of manifold mesh are first preset to reduce the SE by dividing the whole layer sequence into several parts. A breadth-first search-based algorithm has been developed to generate a solid voxelization to get VE. A new parameter RVE is proposed to evaluate the VE caused by the sequence of the layer positions. The RVE slicing is conducted by iteratively adjusting the layer height sequences under different constraint conditions.FindingsThree manifold models are used to verify the proposed method. Compared with uniform slicing with 0.2 mm layer height, cusp height-based method and area deviation-based method, the standard deviations of RVE of all three models are improved under the proposed method. The surface roughness measured by the confocal laser scanning microscope proves that the proposed RVE method can greatly improve part surface quality by minimizing RVE.Originality/valueThis paper proposes an RVE-based method to balance the surface quality and print time. RVE could be calculated by voxelized parts with required accuracy at a very fast speed by parallel.

A novel adaptive slicing algorithm based on ameliorative area ratio and accurate cusp height for 3D printing

PurposeAdaptive slicing is a key step in three-dimensional (3D) printing as it is closely related to the building time and the surface quality. This study aims to develop a novel adaptive slicing method based on ameliorative area ratio and accurate cusp height for 3D printing using stereolithography (STL) models.Design/methodology/approachThe proposed method consists of two stages. In the first stage, the STL model is sliced with constant layer thickness, where an improved algorithm for generating active triangular patches, the list is developed to preprocess the model faster. In the second stage, the model is first divided into several blocks according to the number of contours, then an axis-aligned bounding box-based contour matching algorithm and a polygons intersection algorithm are given to compare the geometric information between several successive layers, which will determine whether these layers can be merged to one.FindingsSeveral benchmarks are applied to verify this new method. Developed method has also been compared with the uniform slicing method and two existing adaptive slicing methods to demonstrate its effectiveness in slicing.Originality/valueCompared with other methods, the method leads to fewer layers whilst keeping the geometric error within a given threshold. It demonstrates that the proposed slicing method can reach a trade-off between the building time and the surface quality.

Quantitative morphometric analysis of molar teeth and alveolar bone using micro-computed tomography in aged mice

ObjectivesIrreversible morphological regressions of the teeth or related structures in older people can diminish their overall health. However, research on human aging in dentistry is complicated by several confounding factors. In this study, we conducted a morphometric analysis of the mandibular second molars and surrounding alveolar bone in C57BL/6 mice to evaluate age-related changes in the oral cavity. MethodsThe animals were divided into five groups based on their age: 4 weeks (juvenile mice; n = 5); 20 weeks (n = 7), 50 weeks (n = 5), 77 weeks (n = 7), and 100 weeks (n = 5); changes were evaluated using micro-computed tomography. ResultsThe molars of juvenile mice had sharp and pointed cusps and presented maximum heights. With age and occlusal wear, the cusp heights demonstrated a significant decrease (up to 75%) until the last stage of life. Conversely, apparent lesions were not observed on the basal portion of the crown, even in the most heavily worn teeth. The roots of the molars continued to grow in length at 4 weeks of age. Alveolar bone resorption begins to occur in middle age and continues throughout life. The proportion of vertical bone loss reached approximately 40% of the entire root length, demonstrating a remarkable increase between weeks 77 and 100. ConclusionsOverall, these morphological changes were similar to those observed in humans. Therefore, it might be appropriate to use aged mice as an experimental model for basic and clinical research in geriatric dentistry.

Quantitative Dental Mesowear Analysis in Domestic Caprids: a New Method to Reconstruct Management Strategies

Dental mesowear is a widely used tool in archaeology and palaeontology for the reconstruction of the overall diet of mammals. This method is based on the characterisation of the height and relief of dental cusps, as they vary according to diet. The use of this method on domestic ungulates presents limitations because (1) currently, very few reference frameworks are available, and (2) the qualitative categorisation of cusps limits our observations and interpretations. In this work, we introduce the analysis of quantitative dental mesowear, based on the measurement of the angle and height of cusps from photographs. The use of this method on 26 present-day domestic sheep with two different feeding strategies showed very significant differences: the group with a dominant rangeland diet has high cusps with acute angles, and the group with a dominant grassland diet has lower cusps with obtuse angles. This method has been compared with the traditional technique of mesowear score, which consists in the qualitative categorisation of cusps into seven categories. However, the analysis showed that mesowear score is more prone to observer error than quantitative mesowear. In addition, quantitative mesowear better reflects the variability in dietary behaviours of extant sheep since observations are not limited into seven categories. To test quantitative mesowear in archaeological samples, we analysed caprine mesowear at two Iron Age sites (sixth-fifth centuries BC) from the northeast of the Iberian Peninsula: Empúries and Ullastret. The results show that caprids at the Ullastret site have a slightly more abrasive diet than at Empúries, which is consistent with data obtained from dental microwear in previous work. Overall, we show the potential of this technique, which can be combined with traditional techniques, to distinguish past caprine feeding strategies.

Senescence-accelerated mouse prone 8 (SAMP8) mice exhibit reduced entoconid in the lower second molar

ObjectiveThe position and size of the major cusps in mammalian molars are arranged in a characteristic pattern that depends on taxonomy. In humans, the cusp which locates distally within each molar is smaller than the mesially located cusp, which is referred to as “distal reduction”. Although this concept has been well-recognized, it is still unclear how this reduction occurs. Current study examined whether senescence-accelerating mouse prone 8 (SAMP8) mice could be a possible animal model for studying how the mammalian molar cusp size is determined. DesignSAMP8 mice were compared with parental control (SAMR1) mice. Microcomputed tomography images of young and aged mice were captured to observe molar cusp morphologies. Cusp height from cement-enamel junction and mesio-distal length of molars were measured. The statistical comparison of the measurements was performed by Mann-Whitney U test. ResultsSAMP8 mice showed reduced development of the disto-lingual cusp (entoconid) of lower second molar when compared with SAMR1 mice. The enamel thickness and structure was disturbed at entoconid, and aged SAMP8 mice displayed severe wear of the entoconid in lower second molar. These phenotypes were observed on both sides of the lower second molar. ConclusionsIn addition to the general senescence phenotype observed in SAMP8 mice, this strain may genetically possess molar cusp phenotypes which is determined prenatally. Further, SAMP8 mice would be a potential model strain to study the genetic causes of the distal reduction of molar cusp size.

English

BACKGROUND The heart is a pair of valved muscular pumps combined in a single organ. For the proper functioning of the heart, all valves should be intact. Mitral valve (MV) prolapse and regurgitation is the main cause of MV replacement. The dimensions of mitral valve and the cusps vary from person to person. We wanted to measure the average size of the valve components with respect to the annulus in the cadavers of South Odisha region, which would help in the selection of prosthetic valve in cardiac surgery. METHODS This comparative study was carried out on 58 adult cadaveric human hearts. Left atrium was opened along the left border of heart so as to expose the mitral orifice. Parameters of different components ofthe valve were measured by using appropriate instruments. RESULTS The mean annular circumference of the mitral valve was found to be 8.84 ± 1.24 cm; The annular attachment and height of anterior cusp were 2.94 ± .81 cm and 2.55 ± 0.27 cm respectively. The annular attachment and height of posterior cusp were 4.52 ± 0.78 cm and 1.2 ± 0.17 respectively. The annular area was found to be 5.22 ± 1.13 cm2. The combined cusp area was found to be 9.38 ± 2.32 cm. CONCLUSIONS The size of mitral valve parameters in the South Odisha region were found to be less compared to other studies. This study might help cardio-thoracic surgeons as well as the prosthetic valve manufacturing companies for the rough estimation of the mitral valve size. KEY WORDS Mitral Valve, Anterior Cusp, Posterior Cusp, Annular Circumference, Annular Valve Area and Combined Cusp Area

Partition-based five-axis tool path generation for freeform surface machining using a non-spherical tool

Freeform surfaces are widely used in many industries for various purposes, and multi-axis CNC machining is the most adopted method for machining them due to its high accuracy and flexibility. The prevailing type of cutter used in machining freeform surfaces is the so-called ball-end type, which is simply a hemisphere and thus has a constant curvature on the cutter surface. Naturally, for a complex surface with a large deviation in curvature, a cutter shape with variable curvature will be more desirable, as we can adaptively choose a portion of smaller curvature on the cutting edge to machine those relatively flat portions on the surface so to enlarge the cutting width and hence reduce the machining time. Towards this objective, in this paper, we present an algorithm which, given an arbitrary freeform surface to machine and a general non-spherical cutter, will generate a five-axis tool path that will strive to match every cutting point on the surface with a locally optimal tool posture (i.e., the contact point on the cutter surface together with the tool orientation) as well as the corresponding optimal feed direction, while both the local gouging-free and global collision-free constraints and the cusp height requirement are all satisfied. The experimental results in both computer simulation and physical machining are also reported, which confirm that, when compared to using a simple ball-end cutter, by using a non-spherical cutter and adaptively adjusting the contacting tool posture and the feed direction, a large improvement in machining efficiency could be achieved, e.g., as much as 60 % achieved in our experiments.

Template-free, microscale dimple patterning of pure titanium surface through anodic dissolution using non-aqueous ethylene glycol-TiCl4 electrolytes

We report a single-step anodic dissolution route for the template-free patterning of pure titanium (Ti) surfaces into a microscale, dimpled topography using non-aqueous ethylene glycol-TiCl4 electrolytes. Anodic dissolution of Ti metal (i.e. 0.04 M Ti4+) into a 40 EG:1 TiCl4 electrolyte was found to induce a predominant change in the anodic dissolution reaction of Ti metal, converting its surface morphology from a slightly-pitted, bright finish into a dimple-patterned surface. The dimple pattern, ca. 4.5 μm in size and 1 μm in cusp height, was found self-organised with no apparent relation to underlying metal grain structure and independent of the applied potential within the anodic current plateau. The origin of the dimple pattern is surmised to arise from a dynamic self-organisation of the anode film, resulting in a Turing structure.

Inter-operative determination of the aortic root and cusp geometry associated with the aortic regurgitation grade.

To perform successful aortic valve plasty (AVP) and valve-sparing root replacement (VSRR), a sufficient understanding of the aortic root and cusp geometry is required. Several key parameters of the aortic root and cusp geometry were, therefore, measured intraoperatively. Forty-nine patients (63.1 ± 16.6 y.o., 40 males) were measured during the surgeries. The patients were divided into 3 groups; including patients with no or mild aortic valve regurgitation (AR) (n = 13), moderate AR (n = 18), and severe AR (n = 18). There were no significant differences in the body surface area (1.72 ± 0.19m2) among the 3 groups (p = 0.858). The effective height (EH) and geometric height (GH) of right coronary cusp were smaller than those of the others (EH: p = 0.068, GH: p < 0.01). The insertion line length (ILL) and free margin length (FML) of each leaflet tended to be significantly longer according to the AR grade(ILL: p < 0.01, FML: p < 0.01). The FML/AVJ ratios were significantly different (p < 0.01). The FML/ILL ratios were constant with the ratio of 0.88 ± 0.1(p = 0.624). Although the ILL and FML tended to increase with the AR grade, the FML/ILL ratio remained constant. For successful AVP and VSRR, adequately maintaining the FML/ILL ratio is necessary to prevent remarkable cusp prolapse while also preserving its favorable cusp motion.

Reimplantation for annular stabilization in bicuspid aortic valve repair.

To review the outcomes of bicuspid aortic valve repair with the reimplantation technique. From 2006 to 2018, 46 patients with bicuspid aortic valve underwent the reimplantation procedure for aortic valve repair. Those patients were included in this study. The mean age was 45 ± 15years and 44 were male. Preoperative echocardiography showed a mean ventriculoaortic junction diameter of 28 ± 3mm. The mean diameter at the sinus of Valsalva was 41 ± 9mm. The minimum cusp height was 19 ± 3mm. Regarding cusp repair technique, central plication was used in 45 patients, free margin reinforcement in 10 patients, and patch repair in 4 patients. Follow-up was performed by annual echocardiography. There were no hospital deaths. All patients were found with either no/trivial or mild AR on postoperative transesophageal echocardiography. The postoperative ventriculoaortic junction diameter was 23 ± 2mm and 83 ± 17% preoperatively. Freedom from moderate AR was 85 ± 6% at 5years, and freedom from reoperation was 93 ± 4% at 5years. Reimplantation for bicuspid aortic valve repair showed acceptable mid-term outcomes.

Species specificity and sexual dimorphism in tooth shape among the three sympatric haplochromine species in Lake Kivu cichlids.

Tooth shape is used to differentiate between morphologically similar species of vertebrates, including fish. This study aimed to quantify tooth shape of three sympatric species: Haplochromis kamiranzovu, H. insidiae, and H. astatodon endemic to Lake Kivu, whose existing identification criteria are currently only qualitative. A quantitative tooth shape analysis was performed based on digitized tooth outline data with a subsequent elliptic Fourier analysis to test for differences among the three species. We looked at crown shape and size differences within H. kamiranzovu and H. insidiae at geographical, habitat, and gender levels. No comparison at habitat level was done for H. astatodon because it is found only in littoral zone. The analysis revealed significant tooth shape differences among the three species. Haplochromis astatodon had a significantly longer major cusp height and a longer and larger minor cusp than that of H. insidiae. It had also a longer major cusp height and a longer and larger minor cusp than that of H. kamiranzovu. Tooth shape differences of H. kamiranzovu and H. insidiae species were not significantly different between littoral and pelagic fish (p > .05) while differences were significant between southern and northern Lake Kivu populations (p < .05). Tooth sizes in H. kamiranzovu and H. insidiae were significantly different, both in height and width as well as in their ratios, and this was true at sex and geographic levels (p < .05), but not at habitat level (p > .05). Tooth shape was also significantly different with sharp teeth for males compared with females of southern populations versus northern ones. These shape‐ and size‐related differences between sexes suggest differences in the foraging strategies toward available food resources in the lake habitat. Further research should explain the genetic basis of the observed pattern.

The history of mesowear: a review.

Published mesowear data was reviewed from the year 2000 to November 2019 (211 publications, 707 species, 1,396 data points). Mesowear is a widely applied tooth wear technique that can be used to infer a herbivore’s diet by scoring the height and sharpness of molar tooth cusps with the naked eye. Established as a fast and efficient tool for paleodiet reconstruction, the technique has seen multiple adaptations, simplifications, and extensions since its establishment, which have become complex to follow. The present study reviews all successive changes and adaptations to the mesowear technique in detail, providing a template for the application of each technique to the research question at hand. In addition, the array of species to which mesowear has been applied, along with the equivalent recorded diets have been compiled here in a large dataset. This review provides an insight into the metrics related to mesowear publication since its establishment. The large dataset overviews whether the species to which the various techniques of mesowear are applied are extant or extinct, their phylogenetic classification, their assigned diets and diet stability between studies, as a resource for future research on the topic.

When morphometry meets taxonomy: morphological variation and species boundaries in Proboscoida (Cnidaria: Hydrozoa)

AbstractSpecies delimitation in marine taxa is often problematic given large intraspecific variation. Based on extensive, recently published genetic sampling from specimens of the hydrozoan families Campanulariidae, Clytiidae and Obeliidae, we evaluate morphological variation in this group, correlating morphometric and phylogenetic patterns for species delimitation. Several species of Campanulariidae are confidently delimited based on differences in size (e.g. Bonneviella species, Tulpa tulipifera and Rhizocaulus verticillatus), while others are re-identified and corroborated based on differences in perisarc thickness (e.g. Silicularia rosea, Orthopyxis and Campanularia species). In Clytiidae, the length and diameter of hydrothecae, height of hydrothecal cusps and perisarc thickness delimit the species Clytia linearis, C. elsaeoswaldae and C. noliformis from others. However, few characters reliably differentiate the clades associated with the nominal species C. gracilis and C. hemisphaerica. In Obeliidae, Obelia geniculata is distinctive in its higher perisarc thickness, and corroborated as a widely distributed species. Obelia longissima and clades refered to O. dichotoma are subtly distinguished, showing a few differences in size and branching of colonies. The taxonomic implications of these results are discussed. With a few exceptions, species can be delimited based on morphometric patterns, once morphological variation is compared.

Cutting Force Simulation in Milling of Tapered Wall with Barrel End Mill

The machinings of aircraft parts and die molds highly require fine surfaces at high production rates in terms of reliability. Barrel end mills having excessively large curvatures on the side cutting edges have recently been applied to finishing of tapered workpiece walls with respect to the cutter rotation axes. Because a large curvature of the cutting edge reduces the cusp height, the tools finish surfaces with small cusp heights in large axial pick feeds. However, in milling with the barrel tool, the cutting force loading in the direction of tool radius increases with the cutting area along the edge. The machining accuracy is deteriorated by tool deflection due to a large cutting force. The wave form is also left on a surface with the tool vibration. Therefore, the cutting parameters should be determined with controlling the cutting force and its direction in milling with the barrel tool. The paper discusses the cutting forces in milling of tapered walls with a barrel end mill in the cutting simulation. The cutting forces are analyzed in the chip flow models interpreted as a piling up of orthogonal cuttings. The shear angle, the shear stress and the friction angle in the cutting model are discussed with the chip flow model. The cutting force characteristics are discussed for the taper angle of the workpiece.

Asymmetric aortic valve is related to development of eccentric aortic regurgitation in patients with tricuspid aortic valve.

It is unclear whether asymmetry itself plays a role in developing eccentric aortic regurgitation (AR) in patients with tricuspid aortic valve (TAV). The aim of this study was to determine whether an asymmetric aortic valve structure may have association with the development of eccentric AR in patients with TAV. Of the 164 410 patients who underwent echocardiography between January 2006 and January 2018 at Dong-A University Hospital, 306 (mean age 69.9±12.6years; 62% men) eccentric AR were identified. After excluding patients with bicuspid and prolapsed AV, 104 patients who had eccentric AR with TAV were enrolled for the study. Comprehensive echocardiographic AV cusp measurements were compared to those of 104 age- and gender-matched control patients with central AR. In the eccentric and central AR groups, 66 (63.5%) and 48 patients (46.2%) had asymmetric AV, respectively. Mean cusp height was significantly larger in the eccentric AR group than in the central AR group (1.8±0.3cm vs 1.7±0.2cm, P=0002). Furthermore, the mean cusp area and average asymmetry index of the cusp area were also significantly larger in the eccentric AR group than in the central AR group (2.6±0.8cm2 vs 2.3±0.6cm2 , P=0.001, and 7.1±4.5% vs 4.9±2.5%, P<0.001, respectively). AV asymmetry indices of eccentric AR were significantly larger than those of patients with central AR. These data suggest that the presence of asymmetric AV might have association with the development of eccentric AR in patients with TAV.

Bicuspid aortic valve repair: systematic review on long-term outcomes.

Many patients with bicuspid aortic valve (BAV) develop aortic regurgitation but are not considered for valve repair. This is partly due to limited long term data regarding repair durability. The purpose of the review is to summarize the long-term (1 year) outcomes of BAV repair. A systematic review was performed to evaluate durability and survival following BAV repair. OVID SP versions of MEDLINE and Embase were searched using 'aortic valve', 'bicuspid', 'repair', 'David' 'Yacoub', 'reimplantation' and 'remodeling'. Initial search produced 770 abstracts, reduced to 92 full papers for review after excluding duplications and abstract review for relevance. Twenty-six studies met full inclusion criteria. BAV repair revealed low operative mortality, with excellent 5-year survival, and low freedom from reoperation. Differences in surgical technique between reimplantation and remodeling do not appear to confer protection against reintervention. Systematic assessment of cusp height and annular stabilization in some form do appear to favor improved long term durability. Leaflet calcification is associated with higher rates of reintervention. BAV repair is associated with acceptable long term survival. Ongoing standardized outcome assessments will further refine surgical techniques associated with excellent repair durability.