The differences between bisecting and off-center cuts of the aortic root: The three-dimensional anatomy of the aortic root reconstructed from the living heart

Perioperative Assessment of the Hemodynamic Ventriculoarterial Junction of the Aortic Root by Three-Dimensional Echocardiography

Improved strategies in aortic valve-preserving operations appreciate the dynamic, three-dimensional complexity of the aortic root and its valve. This depends not only on detailed four-dimensional imaging of the planar dimensions of the aortic root but also on quantitative assessment of the valvar leaflets and their competency. The zones of apposition and resulting hemodynamic ventriculoarterial junction formed in diastole determine valvar competency. Current understanding and assessment of this junction is limited, often relying on intraoperative direct surgical inspection. However, this direct inspection itself is limited by evaluation in a nonhemodynamic state with limited field of view. In this review, we discuss the anatomy of the aortic root, including its hemodynamic junction. We review current echocardiographic approaches toward interrogating the incompetent aortic valve for presurgical planning. Furthermore, we introduce and standardize a complementary approach to assessing this hemodynamic ventriculoarterial junction by three-dimensional echocardiography to further personalize presurgical planning for aortic valve surgery.

Expert Consensus Statement: Anatomy, Imaging, and Nomenclature of Congenital Aortic Root Malformations

Over the past 2 decades, several categorizations have been proposed for the abnormalities of the aortic root. These schemes have mostly been devoid of input from specialists of congenital cardiac disease. The aim of this review is to provide a classification, from the perspective of these specialists, based on an understanding of normal and abnormal morphogenesis and anatomy, with emphasis placed on the features of clinical and surgical relevance. We contend that the description of the congenitally malformed aortic root is simplified when approached in a fashion that recognizes the normal root to be made up of 3 leaflets, supported by their own sinuses, with the sinuses themselves separated by the interleaflet triangles. The malformed root, usually found in the setting of 3 sinuses, can also be found with 2 sinuses, and very rarely with 4 sinuses. This permits description of trisinuate, bisinuate, and quadrisinuate variants, respectively. This feature then provides the basis for classification of the anatomical and functional number of leaflets present. By offering standardized terms and definitions, we submit that our classification will be suitable for those working in all cardiac specialties, whether pediatric or adult. It is of equal value in the settings of acquired or congenital cardiac disease. Our recommendations will serve to amend and/or add to the existing International Paediatric and Congenital Cardiac Code, along with the Eleventh iteration of the International Classification of Diseases provided by the World Health Organization.

Extended law of laplace for measurement of the cloverleaf anatomy of the aortic root

The cross-sectional shape of the aortic root is cloverleaf, not circular, raising controversy regarding how best to measure its radiographic "diameter" for aortic event prediction. We mathematically extended the law of Laplace to estimate aortic wall stress within this cloverleaf region, simultaneously identifying a new metric of aortic root dimension that can be applied to clinical measurement of the aortic root and sinuses of Valsalva on clinical computerized tomographic scans. Enforcing equilibrium between blood pressure and wall stress, finite element computations were performed to evaluate the mathematical derivation. The resulting Laplace diameter was compared with existing methods of aortic root measurement across four patient groups: non-syndromic aneurysm, bicuspid aortic valve, Marfan syndrome, and non-dilated root patients (total 106 patients, 62 M, 44 F). (1) Wall stress: Mean wall stress at the depth of the sinuses followed this equation: Wall stress = BP × Circumscribing circle diameter/(2 × Aortic wall thickness). Therefore, the diameter of the circle enclosing the root cloverleaf, that is, twice the distance between the center, where the sinus-to-commissure lines coincide, and the depth of the sinuses, may replace diameter in the Laplace relation for a cloverleaf cross-section (or any shaped cross-section with two or more planes of symmetry). This mathematically derived result was verified by computational finite element analyses. (2) Diameters: CT scan measurements showed a significant difference between this new metric, the Laplace diameter, and the sinus-to-commissure, mid-sinus-to-mid-sinus, and coronal measurements in all four groups (p-value < 0.05). The average Laplace diameter measurements differed significantly from the other measurements in all patient groups. Among the various possible measurements within the aortic root, the diameter of the circumscribing circle, enclosing the cloverleaf, represents the diameter most closely related to wall stress. This diameter is larger than the other measurements, indicating an underestimation of wall stress by prior measurements, and otherwise provides an unbiased, convenient, consistent, physics-based measurement for clinical use. "Diameter" applies to circles. Our mathematical derivation of an extension of the law of Laplace, from circular to cloverleaf cross-sectional geometries of the aortic root, has implications for measurement of aortic root "diameter." The suggested method is as follows: (1) the "center" of the aortic root is identified by drawing three sinus-to-commissure lines. The intersection of these three lines identifies the "center" of the cloverleaf. (2) The largest radius from this center point to any of the sinuses is identified as the "radius" of the aortic root. (3) This radius is doubled to give the "diameter" of the aortic root. We find that this diameter best corresponds to maximal wall stress in the aortic root. Please note that this diameter defines the smallest circle that completely encloses the cloverleaf shape, touching the depths of all three sinuses.

Expert Consensus Statement: Anatomy, Imaging, and Nomenclature of Congenital Aortic Root Malformations

Over the past 2 decades, several categorizations have been proposed for the abnormalities of the aortic root. These schemes have mostly been devoid of input from specialists of congenital cardiac disease. The aim of this review is to provide a classification, from the perspective of these specialists, based on an understanding of normal and abnormal morphogenesis and anatomy, with emphasis placed on the features of clinical and surgical relevance. We contend that the description of the congenitally malformed aortic root is simplified when approached in a fashion that recognizes the normal root to be made up of 3 leaflets, supported by their own sinuses, with the sinuses themselves separated by the interleaflet triangles. The malformed root, usually found in the setting of 3 sinuses, can also be found with 2 sinuses, and very rarely with 4 sinuses. This permits description of trisinuate, bisinuate, and quadrisinuate variants, respectively. This feature then provides the basis for classification of the anatomical and functional number of leaflets present. By offering standardized terms and definitions, we submit that our classification will be suitable for those working in all cardiac specialties, whether pediatric or adult. It is of equal value in the settings of acquired or congenital cardiac disease. Our recommendations will serve to amend and/or add to the existing International Paediatric and Congenital Cardiac Code, along with the Eleventh iteration of the International Classification of Diseases provided by the World Health Organization.

Aortic root anatomy after aortic valve reimplantation

OBJECTIVE

During the last decade, special concerns have been raised about the anatomic relationships among the sinotubular junction, ventricular-aortic junction, and virtual basal ring to improve the results of root reconstruction. The aim of this study is to evaluate the in vivo anatomy of the aortic root after reimplantation with the Valsalva graft and the anatomic relationship between its components.

METHODS

We analyzed 10 consecutive patients with tricuspid aortic valves who underwent reimplantation with the Valsalva graft between September and December 2019. Surgical clips were applied as markers at the level of proximal annular knots and at the distal reimplanted commissures on the neo-sinotubular junction. Electrocardiogram-gated computed tomography scan of the aortic root was performed. Coordinates of the markers were exported on a 3-dimensional modeling software, and the distances between the virtual basal ring and the Dacron graft basal landmarks were measured.

RESULTS

The mean heights of Dacron graft basal landmarks from virtual basal ring were right-left commissure 7.1 ± 5.1 mm; right sinus 4.7 ± 4.1 mm; right-noncoronary commissure 2.8 ± 2.2 mm; noncoronary sinus 1.4 ± 1.6 mm; left-noncoronary commissure 2.2 ± 2.3 mm; and left sinus 2.0 ± 0.9 mm. The mean planar distances of basal Dacron graft landmarks from virtual basal ring (thickness) were right-left commissure 5.3 ± 3.1 mm; right sinus 2.8 ± 1.4 mm; right-noncoronary commissure 2.2 ± 1.5 mm; noncoronary sinus 1.5 ± 1.5 mm; left-noncoronary commissure 1.3 ± 1.0 mm; and left sinus 3.4 ± 2.5 mm.

CONCLUSIONS

After reimplantation, despite a complete dissection of the root, slight asymmetry of graft proximal seating exists. The inner annuloplasty is on the virtual basal ring, and the proximal edge of the Dacron graft is on the ventricular-aortic junction at a slightly different thickness and height along the annular circumference. At the level of the right sinus and left/right commissure, the Dacron graft is higher than the virtual basal ring and the relative wall thickness is increased. The annular stabilization is unaffected.

Understanding the Aortic Root Using Computed Tomographic Assessment: A Potential Pathway to Improved Customized Surgical Repair

There is continued interest in surgical repair of both the congenitally malformed aortic valve, and the valve with acquired dysfunction. Aortic valvar repair based on a geometric approach has demonstrated improved durability and outcomes. Such an approach requires a thorough comprehension of the complex 3-dimensional anatomy of both the normal and congenitally malformed aortic root. In this review, we provide an understanding of this anatomy based on the features that can accurately be revealed by contrast-enhanced computed tomographic imaging. We highlight the complimentary role that such imaging, with multiplanar reformatting and 3-dimensional reconstructions, can play in selection of patients, and subsequent presurgical planning for valvar repair. The technique compliments other established techniques for perioperative imaging, with echocardiography maintaining its central role in assessment, and enhances direct surgical evaluation. This additive morphological and functional information holds the potential for improving selection of patients, surgical planning, subsequent surgical repair, and hopefully the subsequent outcomes.

Normative Aortic Valvar Measurements in Adults Using Cardiac Computed Tomography - A Potential Guide to Further Sophisticate Aortic Valve-Sparing Surgery

BACKGROUND

A thorough understanding of the anatomy of the aortic valve is necessary for aortic valve-sparing surgery. Normal valvar dimensions and their relationships in the living heart, however, have yet to be fully investigated in a 3-dimensional fashion.Methods and Results:In total, 123 consecutive patients (66±12 years, Men 63%) who underwent coronary computed tomographic angiography were enrolled. Mid-diastolic morphology of the aortic roots, including height of the interleaflet triangles, geometric height, free margin length of each leaflet, effective height, and coaptation length were measured using multiplanar reconstruction images. Average height of the interleaflet triangle, geometric height, free margin length, effective height, and the coaptation length were 17.3±1.8, 14.7±1.3, 32.6±3.6, 8.6±1.4, and 3.2±0.8 mm, respectively. The right coronary aortic leaflet displayed the longest free margin length and shortest geometric height. Geometric height, free margin length, and effective height showed positive correlations with aortic root dimensions. Coaptation length, however, remained constant regardless of aortic root dimensions.

CONCLUSIONS

Diversities, as well as characteristic relationships among each value involving the aortic root, were identified using living-heart datasets. The aortic leaflets demonstrated compensatory elongation along with aortic root dilatation to maintain constant coaptation length. These measurements will serve as the standard value for revealing the underlying mechanism of aortic regurgitation to plan optimal aortic valve-sparing surgery.

Three-dimensional volumetric measurement of the aortic root compared to standard two-dimensional measurements using cardiac computed tomography

INTRODUCTION

Two-dimensional measurements are self-evidently limited when seeking accurately to represent the three-dimensional complexity of the aortic root. Volumetric measurement, therefore, seems an ideal alternative for a more accurate assessment.

MATERIALS AND METHODS

We retrospectively analyzed 123 individuals undergoing cardiac computed tomography. We measured the dimensions of the sinuses of Valsalva using routine multiplanar short axis imaging. Three conventional two-dimensional methods were applied to measure the dimensions of the sinuses. These involved bisecting center of sinus-to-center of interleaflet triangle measures, along with center of sinus-to-center of sinus, and largest sinus-to-sinus measurements. We then quantified the volumes of the root using the volume-rendering method.

RESULTS

The mean dimensions of the sinuses were significantly greater when measured using the largest sinus-to-sinus method as opposed to center of sinus-to-center of interleaflet triangle and center of sinus-to-center of sinus methods (33.6 ± 3.6 mm vs. 31.1 ± 3.1 mm and 30.9 ± 3.3 mm, p < .0001). The mean root volume of 13.6 ± 4.2 ml showed the strongest correlation with the mean dimensions of the sinuses of Valsalva measured using the bisecting method (R² = .8401, p < .0001).

CONCLUSIONS

By using two- and three-dimensional measurements, we have provided average data for the structurally normal aortic root. The differences and correlations encountered should be noted when evaluating and following changes in the diseased root.

The aortic root hexagon as an aide memoire to the important surgical landmarks

BACKGROUND

The anatomy of the aortic root and its relationship to cardiac landmarks is important for valve-sparing surgery and understanding the pathology of lesions arising in this structure. Rapid understanding of the key anatomical details can be achieved by a geometrical concept based on the shape of a hexagon.

METHODS

Definitions, structure, and key anatomical concepts of the aortic root according to the current literature were reviewed. Thirty pig hearts were dissected to explore the relationships of the six points on the aortic root. Six double 2/0 ethibond needles were placed into the six points at 90°. The passage of the needles through the specific cardiac landmarks at each point was noted. The aortic root hexagon is a geometrical structure formed by two triangles superimposed on each other. The six points in the hexagon relate to important adjacent cardiac landmarks.

RESULTS

The two best-known anatomical relationships are of the left-non coronary aortic commissure to the longitudinal axis of symmetry of the aortic leaflet of the mitral valve and the relationship of the nadir of the noncoronary aortic valve leaflet to the medial commissure of the mitral valve. The other four points are related to equally significant and well defined anatomical landmarks.

CONCLUSION

The aortic root hexagon is made by two triangles superimposed on each other, these are the commissural and nadir triangles respectively. We have found this concept to be a quick way to learn and remember the key anatomical relationships of the aortic root.

Surgical anatomy of the aortic valve and root-implications for valve repair

The aortic root is an important anatomical structure positioned at the center of the heart, making it critical to the functioning of the major cardiac chambers. Deep knowledge of the anatomical "surroundings" of the aortic root is crucial for surgeon attempting to spare or repair a leaking aortic valve. In fact, root dissection is a necessary step to "skeletonize" the aortic valve, allowing the surgeon to work on the critical components of its structure, namely the aorto-ventricular junction, the virtual basal ring (VBR) and the sino-tubular junction (STJ). These three components, along with the insertion of the leaflet to the aortic wall, form the skeleton of the aortic valve that is essential in guaranteeing valve competence. A good anatomical proportion between the various component of the skeleton of the aortic valve need to be verified, or re-established in order to set the basis for an optimal aortic valve repair. Once the skeleton of the heart has been correctly addressed, the condition of the valve leaflets need to be considered. Excess of leaflet tissue is treated by leaflet plication or resection and lack of leaflet tissue is addressed by tissue extension with autologous or heterologous materials. In the present manuscript, we highlight the principal structure of the aortic root and describe in detail each anatomical component. This basic anatomical knowledge is also important for a through understanding of the normal function of the valve and root structure during the cardiac cycle. The close boundaries existing between the left ventricular cavity and the aorta are important in explaining the sophisticated function of opening and closing of the aortic valve. Similarly, the role played by the sinuses of Valsalva in regulating the blood flow exiting the ventricle underline the concept that "form follows function" and emphasizes the importance of a good anatomical reconstruction for an optimal and long-lasting valve function.

What is the real cardiac anatomy?

The heart is a remarkably complex organ. Teaching its details to medical students and clinical trainees can be very difficult. Despite the complexity, accurate recognition of these details is a pre‐requisite for the subsequent understanding of clinical cardiologists and cardiac surgeons. A recent publication promoted the benefits of virtual reconstructions in facilitating the initial understanding achieved by medical students. If such teaching is to achieve its greatest value, the datasets used to provide the virtual images should themselves be anatomically accurate. They should also take note of a basic rule of human anatomy, namely that components of all organs should be described as they are normally situated within the body. It is almost universal at present for textbooks of anatomy to illustrate the heart as if removed from the body and positioned on its apex, the so‐called Valentine situation. In the years prior to the emergence of interventional techniques to treat cardiac diseases, this approach was of limited significance. Nowadays, therapeutic interventions are commonplace worldwide. Advances in three‐dimensional imaging technology, furthermore, now mean that the separate components of the heart can readily be segmented, and then shown in attitudinally appropriate fashion. In this review, we demonstrate how such virtual dissection of computed tomographic datasets in attitudinally appropriate fashion reveals the true details of cardiac anatomy. The virtual approach to teaching the arrangement of the cardiac components has much to commend it. If it is to be used, nonetheless, the anatomical details on which the reconstructions are based must be accurate. Clin. Anat. 32:288–309, 2019. © 2019 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Screening for thoracic aortic pathology: Clinical practice in a single tertiary center

OBJECTIVE

The aim is to present current clinical practice of thoracic aorta screening in a tertiary referral center. We identified how often imaging techniques were used for screening and established the value of transthoracic echocardiography (TTE) in comparison with computed tomography (CT) to detect aortic dilation. We also investigated which additional abnormalities of the heart, aorta or smaller arteries were discovered.

DESIGN

All patients ≥15 years who visited our tertiary center in 2012-2016 for first thoracic aortic screening were retrospectively included. Diameters of the sinus of Valsalva (SoV) and maximum ascending aorta (AA) were compared between TTE and CT. The sensitivity and specificity of TTE to detect aortic dilation (≥40 mm) was assessed with CT as reference standard. Intracardiac abnormalities found with TTE and arterial abnormalities found with CT were identified.

RESULTS

In total 349 patients (155 men, age 41 ± 15 years, 10% genetic mutation) were included. Screening was performed with TTE only in 35% and with TTE and CT in 65%. Patients who underwent TTE only were younger, had less often hypertension and less often a family history of aortic pathology. Although there was a good correlation between TTE and CT, the diameters measured with TTE were typically lower (SoV -1.0, 95%CI -6.6 to 4.7 and AA -0.4, 95%CI -6.5 to 5.8). Sensitivity of TTE for detecting aortic dilation was 61% (SoV) and 57% (AA) and specificity was 96% (SoV) and 100% (AA). Valve abnormalities, ventricular dilation or reduced ventricular function was found with TTE in 26 patients (7%). In 47 patients (13%) ascending aortic dilation was diagnosed and in 10 patients (4%) relevant peripheral arterial abnormalities were identified using CT.

CONCLUSIONS

Most often patients received both TTE and CT (65%). Since TTE showed a low sensitivity to detect aortic dilation, CT imaging is advised at least once in patients referred for thoracic aortic screening.