Aortic Shape Research Articles

Valsalva sinus asymmetry in bicuspid aortic valve: diameter through fused cusp is smaller than diameter through nonfused cusp but maximal diameter is the same whatever the phenotype when estimated by CMR

Background Previous studies establish a link between bicuspid aortic valve (BAV) morphology and aortic shape. Anteroposterior (AP) leaflets with right left (RL) fusion was found more often associated with dilatation of VS than left-right (LR) leaflets with either fusion between right and noncoronary(R-NC) cusps or between left and noncoronary cusps(L-NC). However, most of these studies were performed by transthoracic echocardiography with parasternal long axis view measurements without taking into account a possible valsalva sinus (VS) asymmetry. The aim of our study was to assess aortic valsalva sinus size and morphology by CMR in a large cohort of BAV subjects.

OS2-6 Application of Computational Fluid Dynamics and Genetic Algorithms to Investigate Effectiveness of Hemodynamic Factors to Determine Abdominal Aortic Bifurcation Shapes(OS2: Integrated Nano-Biomechanics)

OS2-6 Application of Computational Fluid Dynamics and Genetic Algorithms to Investigate Effectiveness of Hemodynamic Factors to Determine Abdominal Aortic Bifurcation Shapes(OS2: Integrated Nano-Biomechanics)

Abstract 20549: Patient-Specific CT Image-Based Engineering Analysis of Transcatheter Aortic Valve Replacement - Implications for Aortic Root Rupture

Introduction: Despite the increased global experience with transcatheter aortic valve replacement (TAVR), there remain major adverse clinical events. One of the most severe complications of TAVR is aortic rupture. Although several clinical risk factors of TAVR-induced rupture have been identified, the mechanisms remain largely unknown. The objective of this study was to use computational models to predict potential aortic rupture in TAVR patients. Methods: Pre-procedural CT scans of TAVR patients were used to reconstruct patient-specific finite element (FE) models, which included the aortic root, aortic leaflets, calcification, mitral-aortic intervalvular fibrosa, anterior mitral leaflet, fibrous trigones, and left ventricle. Stent deployment was simulated in a total of 25 patients to evaluate the potential for aortic rupture. Our research design consisted of two phases: Phase One, which was to develop and calibrate FE modeling techniques by retrospectively analyzing 7 Edwards SAPIEN cases with known results; and Phase Two, which was to implement the modeling methodology developed in Phase One to conduct a blind study of 18 cases from a database of 60 patients consisting of 50% rupture cases. For the blind study, FE simulations were completed by researchers blind to the clinical outcomes, and data analysis was conducted by an independent researcher. Results: Simulations correctly predicted 83% of the rupture cases. The balloon pressure at time of rupture was approximately 3.52 atm and 2.53 atm for SAPIEN 23 and 26 valves, respectively. The average contact force between the stent and native tissue was about 81N. Conclusion: Our analysis of over 18 patients suggested that the TAVR outcome could depend on the patient-specific aortic sinus shape, calcification volume, shape, location, and orientation. These results demonstrate the potential for simulation-based pre-TAVR planning tools to evaluate device performance and improve clinical outcomes.

Comparison of hinge microflow fields of bileaflet mechanical heart valves implanted in different sinus shape and downstream geometry

The characterization of the bileaflet mechanical heart valves (BMHVs) hinge microflow fields is a crucial step in heart valve engineering. Earlier in vitro studies of BMHV hinge flow at the aorta position in idealized straight pipes have shown that the aortic sinus shapes and sizes may have a direct impact on hinge microflow fields. In this paper, we used a numerical study to look at how different aortic sinus shapes, the downstream aortic arch geometry, and the location of the hinge recess can influence the flow fields in the hinge regions. Two geometric models for sinus were investigated: a simplified axisymmetric sinus and an idealized three-sinus aortic root model, with two different downstream geometries: a straight pipe and a simplified curved aortic arch. The flow fields of a 29-mm St Jude Medical BMHV with its four hinges were investigated. The simulations were performed throughout the entire cardiac cycle. At peak systole, recirculating flows were observed in curved downsteam aortic arch unlike in straight downstream pipe. Highly complex three-dimensional leakage flow through the hinge gap was observed in the simulation results during early diastole with the highest velocity at 4.7 m/s, whose intensity decreased toward late diastole. Also, elevated wall shear stresses were observed in the ventricular regions of the hinge recess with the highest recorded at 1.65 kPa. Different flow patterns were observed between the hinge regions in straight pipe and curved aortic arch models. We compared the four hinge regions at peak systole in an aortic arch downstream model and found that each individual hinge did not vary much in terms of the leakage flow rate through the valves.

The ascending aorta with bicuspid aortic valve: a phenotypic classification with potential prognostic significance

Different methods to classify the anatomical configurations of the aorta with bicuspid aortic valve (BAV) have been proposed. We aimed to test them in terms of descriptive power (i.e. capability to identify different clusters of patients with unique associations of anatomo-clinical features) and possible prognostic significance. A consecutive echocardiographic series of 696 BAV patients (mean age 48 ± 16 years, male:female ratio 3:1) was analysed. Three possible schemes for classification of the patterns of aortic dimensions were compared. One defined the aortic shape as 'N' (ascending < sinuses > sinotubular junction (STJ)), 'A' (ascending > sinuses > STJ) or 'E' (sinotubular ≥ sinuses), the second as 'non-dilated', 'ascending phenotype' (dilated, with ascending > sinuses) or 'root phenotype' (dilated, with sinuses > ascending) and the third as normal, 'type I' (dilated only at the ascending tract), 'type II' (dilated at both ascending and sinus levels) or 'type III' (dilated only at the sinuses). We evaluated the correlation with valve morphotypes (right-left fusion, right-non-coronary fusion) and patient characteristics. In a smaller longitudinal study (n = 150), the occurrence of fast growth of the aorta (fifth quintile: ≥1 mm/year) during follow-up (5 ± 3 years) in the various phenotypes was assessed. The three classification methods proved meaningful in terms of association with valve morphotypes: significant associations were found between right-left-coronary BAV and the root phenotype (P < 0.001) and between the right-non-coronary BAV and the shapes A and E (P<0.001) as well as type I aortic configuration (P < 0.001). The aortic shape showed significant association with five of the other tested clinical variables, the phenotype and the type of dilatation with eight. In the longitudinal study, the root phenotype showed the most significant association with fast growth (>1 mm/year) of the ascending diameter (50% root phenotype patients; P = 0.005). The association with the N type was weaker (P = 0.055); no association was found with types from the other classification scheme (P = 0.42). When tested on a large population, three previously suggested phenotypic classifications of the BAV aorta proved to categorize patients into significantly different clusters, but only the classification system distinguishing between ascending phenotype and root phenotype showed a potential prognostic value. Phenotypic class of the aorta could be a factor to integrate in future comprehensive models for risk stratification of BAV aortopathy.

Hemodynamics in bicuspid aortic valve relatives with trileaflet aortic valves compared to normal controls using 4D flow MRI

Background Bicuspid aortic valve (BAV) is known as the most common congenital anomaly and its complications (ascending aortic aneurysm, dissection) can lead to noticeable morbidity and mortality. There is increasing evidence that, in addition to its genetic background, changes in aortic hemodynamics may play an important role in the development of aortopathy in these patients. Studies have shown that BAV can substantially alter aortic hemodynamics, but it is unclear if the genetic basis can influence aortic properties and 3D blood flow in BAV relatives with normal tricuspid valves. In this study, we evaluated flow dynamics, aorta diameter and geometry in BAV relatives compared to normal volunteers using 4D flow MRI. Methods 15 controls and 3 families with one known BAV case in each family (Figure 1) underwent contrast agent enhanced (BAV relatives: MultiHance, controls: Ablavar) MRI (1.5 or 3T, Siemens, Germany) for the evaluation of ascending aorta (AAo) dimensions, aortic valve morphology, aortic shape, width to height ratio, and aortic 3D blood flow dynamics. To assess valve morphology and global cardiac function, breath-held, ECG-gated time-resolved (CINE) 2D balanced SSFP images were acquired. Aortic blood flow assessment was done using ECG and respiratory-gated CINE 3D phase-contrast MRI with 3D velocity encoding (4D flow) and full volumetric coverage (VENC = 150-250 cm/s, temporal resolution = 38.4-40.0 ms). Net flow and peak velocity were measured at the level of SOV (sinuses of valsalva), AAo (proximal to brachiocephalic trunk), distal aortic arch and descending aorta (DAo, level of left atrium) using commercial software (Ensight, CEI, NC). The presence and severity of helix and vortex flow was assessed by two readers using a defined 3-point grading scale in a blinded manner. Results Vortex and helix flow grading was performed with excellent inter-observer agreement (Cohen’ sk appa, = 0.73). Vortex flow was significantly more frequent in BAV relatives compared to controls (Figure 2, p < 0.001). Specifically, vortex flow was increased in the AAo (p < 0.004) and DAo (p < 0.025). Helix flow and flow parameters were similar in BAV relatives and controls. 47% of all BAV relatives had a different (p < 0.007) aortic shape than the typical round shape of the controls (93.3%). Peak velocity was reduced (p = 0.009) for gothic aortas and more vortices were found in cubic aortas (p < 0.001).

Numerical validation of a suprasystolic brachial cuff-based method for estimating aortic pressure

Central aortic pressures are better predictors of cardiovascular events than peripheral pressures. However, central aortic blood pressures cannot be measured noninvasively; for this reason, estimating aortic pressures from noninvasive measurements of peripheral pressures has been the subject of numerous studies. In the present study, a novel method was proposed to noninvasively estimate aortic pressures from the oscillometric wave of a suprasystolic brachial cuff. The errors of estimation were evaluated in relation to various cardiovascular properties using an integrated cardiovascular-cuff model. Obtained results demonstrated that the estimation errors are affected mainly by aortic stiffness. The estimation errors for aortic systolic pressure, diastolic pressure, pulse pressure and wave shape under the assumed cardiovascular conditions were 5.84 ± 1.58 mmHg, -0.28 ± 0.41 mmHg, 6.12 ± 1.42 mmHg and 1.72 ± 0.57 mmHg, respectively, all of which fell within the error ranges established by existing devices. Since the method is easy to be automated and bases the estimation fully on patient-specific information, its clinical application is promising, although further clinical studies are awaited to validate the method in vivo.

412 大血管転換術後の胸大動脈形状が血液流れにおよぼす影響の数値解析(GS-5 生物流体)

412 大血管転換術後の胸大動脈形状が血液流れにおよぼす影響の数値解析(GS-5 生物流体)

Dorso-ventral contributions in the formation of the embryonic aorta and the control of aortic hematopoiesis

The embryonic dorsal aorta plays a pivotal role in the production of the first hematopoietic stem cells (HSCs), the founders of the adult hematopoietic system. HSC production is polarized by being restricted to the aortic floor where a specialized subset of endothelial cells (ECs) endowed with hemogenic properties undergo an endothelial-to-hematopoietic production resulting in the formation of the intra-aortic hematopoietic clusters. This production is tightly time- and space-controlled with the transcription factor Runx1 playing a key role in this process and the surrounding tissues controlling the aortic shape and fate. In this paper, we shall review (a) how hemogenic ECs differentiate from the mesoderm, (b) how the different aortic components assemble coordinately to establish the dorso-ventral polarity, and (c) how this results in the initiation of Runx1 expression in hemogenic ECs and the initiation of the hematopoietic program. These observations should elucidate the first steps in HSC commitment and help in developing techniques to manipulate adult HSCs.

Bicuspid aortic valve phenotype relationship with aortic root morphology and elasticity

Background: Bicuspid Aortic Valve (BAV) affects about 0.5% to 2% of the population and predisposes patients to aortic stenosis or aortic dilation and dissection. Aortic size, morphology and elastic properties are thought to be related to BAV phenotype. Methods: In this retrospective study of 88 consecutive patients with BAV referred for transesophageal echocardiography, we aimed to determine aortic size, aortic root morphology and elastic properties. Distensibility, strain and stiffness index were calculated using cuff blood pressure in 37 patients without aortic stenosis or regurtiation. Results: Mean age of the patients was 40.3 years and 64 (72,7%) were men. We detected 51 (58%) patients with type 1 (right–left leaflet orientation), 10 (11, 3%) patients with type 2 (right-noncoronary leaflet orientation), 3 (3,4%) patients with type 3 (left –noncoronary leaflet orientation) and 24 (27,3%) patients without raphe. Among 51 patients with type 1 BAV with raphe 31 (60,8%) had type A (assendan aorta size>sinus of Valsalva size> sinotubulary junction size), 18 (35,3%) had type N (assendan aorta size≤sinus of Valsalva size > sinotubulary junction size) and 2 (3,9%) had type E (sinus of Valsalva size≤ sinotubulary junction size) aortic root morphology. Thirteen BAV patients without raphe (54,2%) had type A, 8 (33,3%) had type N and 3 (12,5%) had type E aortic root morphology. Type 2 BAV patients with raphe either had type N [5 (50%)] or type A [5 (50%)] aortic root morphology. Among patients with type 3 BAV with raphe 2 (66,7%) patients had type A, 1 (33,3%) had type N aortic root morphology. Aortic strain (AS), distensibility (D) were significantly higher and stiffness index (SI) was significantly lower in BAV with raphe compared to patients without raphe: AS: 7,39±2,9, D: 4,13±2, SI: 6,77±4,4 versus AS: 5,57±2,3, D: 2,77±1, SI: 8,04±3,1; p<0,05 for all parametres. There was no difference between root type A and root type N morphology as regards elasticity. Aortic distensibility and strain were negatively correlated with age and a positive correlation was detected between age and aortic root size. Conclusion: Our study showed no relation between aortic valve morphology and the aortic root shape. The finding of lower aortic distensibility in BAV patients without raphe may imply earlier aortic size increase predisposing to complications which must be investigated with further long term studies.

Shape of the dilated aorta in children with bicuspid aortic valve

Background:The dilated aorta in adults with bicuspid aortic valve has been shown to have different shapes, but it is not known if this occurs in children. This observational study was performed to determine if there are different shapes of the dilated aorta in children with bicuspid aortic valve and their association with age, gender, hemodynamic alterations, and degree of aortic enlargement.Methods:One hundred and eighty-seven echocardiograms done on pediatric patients (0 – 18 years) for bicuspid aortic valve, during 2008, were reviewed. Aortic valve morphology, shape/size of the aorta, and pertinent hemodynamic alterations were documented. Aortic dilation was felt to be present when at least one aortic segment had a z-score > 2.0; global aortic enlargement was determined by summing the aortic segment z-scores. The aortic shape was assessed by age, gender, valve morphology, and hemodynamic alterations.Results:Aortic dilation was present in 104/187 patients. The aorta had six different shapes designated from S1 through S6. There was no association between the aortic shape and gender, aortic valve morphology, or hemodynamic abnormalities. S3 was the most common after the age of six years and was associated with the most significant degree of global aortic enlargement.Conclusions:The shape of the dilated aorta in children with bicuspid aortic valve does not occur in a uniform manner and multiple shapes are seen. S2 and S3 are most commonly seen. As aortic dilation becomes more significant, a single shape (S3) becomes the dominant pattern.

Abnormalities in aortic arch geometry do not lead to reduced exercise performance: a comparison study between patients with transposition of the great arteries repaired by arterial switch operation and normal controls

Background Abnormal aortic arch geometry, in particular the ‘gothic arch’, has been associated with reduced exercise performance in patients with repaired aortic coarctation. Following the arterial switch operation (ASO) for transposition of the great arteries (TGA), the morphology of the aorta is also known to be abnormal, presenting with dilated aortic root and ‘gothic’ deformity of the aortic arch. In this study, our aim was to compare aortic geometry between normal and ASO patients to establish if aortic arch shape influenced exercise performance.

Quantitative Assessment of Asymmetric Aortic Dilation with Valve-related Aortic Disease

Previous work suggests that ascending aortic (AsAo) dilation can be asymmetric and is potentially related to valve-related blood flow abnormalities. The aim of this study was to investigate the relationship between the aortic valve and AsAo dilation using a quantitative, three-dimensional assessment of aortic shapes. Computed tomographic and magnetic resonance images of the thorax were retrospectively reviewed. Four groups with aortic dilation were studied: those with tricuspid aortic valves (TAVs) with and without stenosis and those with bicuspid aortic valves (BAVs) with and without stenosis. Controls had either TAVs or BAVs but no aortic stenosis or dilation. In additional to standard orthogonal diameters, a unique measurement of AsAo asymmetry was used: the ratio of the greater to lesser curvatures measured using three-dimensional reformats in a "candy-cane" orientation. A total of 105 patients were identified. Ratios of greater to lesser curvature in patients with aortic dilation and nonstenotic TAVs were not significantly different from those in controls (1.69 vs 1.55, P > .20), but the asymmetry reflected by this ratio was markedly increased in patients with aortic dilation and stenotic TAVs (1.94, P < .001). Patients with aortic dilation and BAVs had significantly elevated ratios regardless of the status of the aortic valve (1.96 for nonstenotic and 2.05 for stenotic vs 1.53 for controls, P < .001). Asymmetric AsAo dilation with relative bulging of the greater curvature is linked to aortic stenosis, but it is also seen with nonstenotic BAVs. This suggests that the hemodynamic forces that contribute to aortic dilation are not fully revealed by conventional assessment of the aortic valve.

Changes in aortic shape and diameters after death: Comparison of early postmortem computed tomography with antemortem computed tomography

PurposeThe purpose of this study is to evaluate the postmortem deformation of the aorta on postmortem computed tomography (CT) by comparison with the antemortem CT in the same patient. Materials and methodsA total of 58 non-traumatic patients without hemorrhagic events who underwent torso CT before and shortly after death were enrolled. Antemortem chest and abdominal CT were obtained in 44 cases and in 57 cases, respectively. The lengths of the major and minor axes of the ascending and descending thoracic aorta and the abdominal aorta were measured on both antemortem and postmortem CT in the same patient. To evaluate the shape of the aorta, the major axis–minor axis ratio (Ma-MiR) was calculated. Mean values of the diameters of the aorta and Ma-MiRs on postmortem CT were compared with those on antemortem CT using the Wilcoxon signed-rank test. We also evaluated the major and minor axes and Ma-MiRs on both antemortem and postmortem CT in two age groups: 65 years and under (n=13) and over 65 years (n=45). ResultsAt each level tested, the aorta significantly shrank after death (p<0.001) (ascending thoracic aorta, descending thoracic aorta, and abdominal aorta: 38.5mm×33.5mm, 28.0mm×25.9mm, and 24.4mm×21.8mm on antemortem CT, 30.0mm×26.2mm, 24.4mm×20.7mm, and 21.5mm×14.5mm on postmortem CT, respectively). The postmortem Ma-MiRs significantly increased at the descending thoracic aorta and the abdominal aorta (p<0.001). The diameters of the aorta are longer in older cases at all levels on both antemortem and postmortem CT. The reduction rates were larger in younger cases than older cases at all levels. ConclusionsAfter death, the aorta shrunk at all levels, and became oval in shape in descending thoracic and abdominal aorta. The contraction was greater in younger cases than older cases. Investigators who interpret postmortem imaging should be aware of the postmortem deformation of the aorta.

Relation of Bicuspid Aortic Valve Morphology to the Dilatation Pattern of the Proximal Aorta: Focus on the Transvalvular Flow

Whether the dilatation of proximal aorta in patients with bicuspid aortic valve is secondary to hemodynamic effects related to the abnormal aortic valve or a primary manifestation of the genetic disorder remains controversial. We discuss in this paper the recent data on the BAV function and transvalvular flow patterns in relation with the dilatation type of the proximal aorta. Different morphological forms of bicuspid aortic valve in relation with the specific transvalvular blood flow patterns are focus of the first paragraph of this paper. In the second part of this paper we present the pathogenetic insight into the different clinically observed phenotypes of bicuspid aortic valve disease (i.e., association of proximal aortic shapes with the specific cusp fusion patterns), based on the data from recent rheological studies.

Aging Impact on Thoracic Aorta 3D Morphometry in Intermediate-Risk Subjects: Looking Beyond Coronary Arteries with Non-Contrast Cardiac CT

An increasing number of intermediate risk asymptomatic subjects benefit from measures of atherosclerosis burden like coronary artery calcification studies with non-contrast heart computed tomography (CT). However, additional information can be derived from these studies, looking beyond the coronary arteries and without exposing the patients to further radiation. We report a semi-automatic method that objectively assesses ascending, arch and descending aorta dimension and shape from non-contrast CT datasets to investigate the effect of aging on thoracic aorta geometry. First, the segmentation process identifies the vessel centerline coordinates following a toroidal path for the curvilinear portion and axial planes for descending aorta. Then, reconstructing oblique planes orthogonal to the centerline direction, it iteratively fits circles inside the vessel cross-section. Finally, regional thoracic aorta dimensions (diameter, volume and length) and shape (vessel curvature and tortuosity) are calculated. A population of 200 normotensive men was recruited. Length, mean diameter and volume differed by 1.2 cm, 0.13 cm and 21 cm(3) per decade of life, respectively. Aortic shape uncoiled with aging, reducing its tortuosity and increasing its radius of curvature. The arch was the most affected segment. In conclusion, non-contrast cardiac CT imaging can be successfully employed to assess thoracic aorta 3D morphometry.

Marked three-dimensional flow pattern changes in distorted aortic geometry

Functional cardiovascular magnetic resonance imaging (MRI) was performed in a 72-year-old female patient who underwent MRI to detect aortic high-risk plaques as a potential source of embolic stroke. Magnetic resonance imaging revealed an unusually complex aortic shape including kinking and elongation of the descending aorta (DAo). To analyse haemodynamic consequences of these geometric changes, …

The Influence of Different Types of Stent Grafts on Aneurysm Neck Dynamics after Endovascular Aneurysm Repair

Objective: Dynamic imaging provides insight into aortic shape changes throughout the cardiac cycle. These changes may be important for proximal aortic stent graft fixation, sealing and durability. The objective of this study is to analyse the influence of different types of stent grafts on dynamic changes of the aneurysm neck. Methods: Pre- and postoperative electrocardiography (ECG)-gated computed tomographic angiography (CTA) scans were obtained in 30 abdominal aortic aneurysm (AAA) patients, 10 each from three different types of stent grafts (10 Talent, Endurant, and Excluder). Each dynamic CTA dataset consisted of eight reconstructed images over the cardiac cycle. Aortic area and radius changes during the cardiac cycle were determined at two levels: (A) 3 cm above and (B) 1 cm below the lowermost renal artery. Radius changes were measured over 360 axes, and plotted in a polar plot. An ellipse was fitted over the plots to determine radius changes over the major and minor axis for assessment of the asymmetric aspect and most prominent direction of distension. Results: Baseline characteristics did not differ significantly between the three groups. Preoperatively, the aortic area increased significantly (p < 0.001) over the cardiac cycle in all patients at both levels: (A) mean increase 8.3 ± 4.1% (2.0–17.3%); (B) mean increase 5.9 ± 4.2% (1.9–12.4%). The postoperative aortic area increase over the cardiac cycle did not differ significantly from preoperative increases: (A) mean increase 9.9 ± 2.2% (4.4–20.0%); (B) mean increase 7.7 ± 2.4% (3.8–12.4%). The difference between radius change over the major and minor axis was significant both pre- and postoperatively for all three stent grafts, indicating asymmetric distension. Suprarenal, the distension showed a tendency to right-anterior and infrarenal to left-anterior. The distension and direction of the aortic expansion was preserved after stent grafting. There were no differences between the three types of stent grafts regarding their impact on the aortic distension or direction of this distension. Conclusion: The aorta expands significantly and asymmetrically throughout the cardiac cycle. After implantation of abdominal aortic stent grafts, the aortic distension and direction of distension remain equally preserved in all three groups. The three stent graft types studied seem to be able to adapt to the asymmetric dynamic aortic shape changes.

The Influence of Different Types of Stent Grafts on Aneurysm Neck Dynamics after Endovascular Aneurysm Repair

Dynamic imaging provides insight into aortic shape changes throughout the cardiac cycle. These changes may be important for proximal aortic stent graft fixation, sealing and durability. The objective of this study is to analyse the influence of different types of stent grafts on dynamic changes of the aneurysm neck. Pre- and postoperative electrocardiography (ECG)-gated computed tomographic angiography (CTA) scans were obtained in 30 abdominal aortic aneurysm (AAA) patients, 10 each from three different types of stent grafts (10 Talent, Endurant, and Excluder). Each dynamic CTA dataset consisted of eight reconstructed images over the cardiac cycle. Aortic area and radius changes during the cardiac cycle were determined at two levels: (A) 3 cm above and (B) 1 cm below the lowermost renal artery. Radius changes were measured over 360 axes, and plotted in a polar plot. An ellipse was fitted over the plots to determine radius changes over the major and minor axis for assessment of the asymmetric aspect and most prominent direction of distension. Baseline characteristics did not differ significantly between the three groups. Preoperatively, the aortic area increased significantly (p < 0.001) over the cardiac cycle in all patients at both levels: (A) mean increase 8.3 +/- 4.1% (2.0-17.3%); (B) mean increase 5.9 +/- 4.2% (1.9-12.4%). The postoperative aortic area increase over the cardiac cycle did not differ significantly from preoperative increases: (A) mean increase 9.9 +/- 2.2% (4.4-20.0%); (B) mean increase 7.7 +/- 2.4% (3.8-12.4%). The difference between radius change over the major and minor axis was significant both pre- and postoperatively for all three stent grafts, indicating asymmetric distension. Suprarenal, the distension showed a tendency to right-anterior and infrarenal to left-anterior. The distension and direction of the aortic expansion was preserved after stent grafting. There were no differences between the three types of stent grafts regarding their impact on the aortic distension or direction of this distension. The aorta expands significantly and asymmetrically throughout the cardiac cycle. After implantation of abdominal aortic stent grafts, the aortic distension and direction of distension remain equally preserved in all three groups. The three stent graft types studied seem to be able to adapt to the asymmetric dynamic aortic shape changes.

Dynamics of the Aorta Before and After Endovascular Aneurysm Repair: A Systematic Review

An overview of the knowledge of thoracic (TAA), and abdominal aortic aneurysm (AAA) dynamics, before and after endovascular repair, is given. Medline, EMBASE and the Cochrane database were searched for relevant articles. After inclusion and exclusion, 25 relevant articles reporting on aneurysm dynamics remained, allowing for comparison. Results provided in the included studies were assumed (statistically) significant if they were larger than the repeatability of the used method. The sample size of dynamic studies is limited and translational studies are missing. Magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) were shown to have lower inter-observer variabilities than ultrasonography (US). The distension of several relevant stent-graft-landing zones during the cardiac cycle in both the abdominal and thoracic aorta are significant (mean diameter change of the AAA neck in the included studies ranged from 0.9 mm to 2.4 mm; mean area change of the thoracic aorta ranged from 4.8% to 12.7% at various levels). This distension remained preserved after stent-graft placement. Preoperatively, the renal arteries displace per heartbeat. Significant movement of the aorta in the anteroposterior (AP) and lateral direction, during the cardiac cycle, was observed. The aorta exhibits a wide variety of morphologic changes throughout the cardiac cycle. CTA and MRA are reliable modalities to investigate aortic shape changes during the cardiac cycle. Significant changes per heartbeat are reported in the AAA neck and thoracic aorta. The renal artery displaces per heartbeat. The clinical relevance of dynamic imaging has not been proven yet, but dynamic changes of the aorta have to be taken into account in stent-graft selection and future stent-graft design.