Different hemodynamic stress of the ascending aorta wall in patients with bicuspid and tricuspid aortic valve

It is unclear whether ascending aorta dilation in patients with bicuspid aortic valve is caused by abnormal hemodynamics or by a common developmental defect of the aortic valve and aortic wall. We performed an echocardiographic study to examine the differences in hemodynamic stress at the ascending aorta in patients with bicuspid and tricuspid aortic valve. We studied prospectively 58 consecutive patients referred for preoperative echocardiographic examination with aortic valve stenosis and either bicuspid or tricuspid valve and an ascending aortic diameter of 相似文献   

Aortic shear stress in patients with bicuspid aortic valve with stenosis and insufficiency

Objectives

Bicuspid aortic valve, characterized by valve malformation and risk for aortopathy, displays profound alteration in systolic aortic outflow and wall shear stress distribution. The present study performed 4-dimensional flow magnetic resonance imaging in patients with bicuspid aortic valve with right-left cusp fusion, focusing on the impact of valve function on hemodynamic status within the ascending aorta.

Three‐dimensional parametric modeling of bicuspid aortopathy and comparison with computational flow predictions

Bicuspid aortic valve (BAV)‐associated ascending aneurysmal aortopathy (namely “bicuspid aortopathy”) is a heterogeneous disease making surgeon predictions particularly challenging. Computational flow analysis can be used to evaluate the BAV‐related hemodynamic disturbances, which likely lead to aneurysm enlargement and progression. However, the anatomic reconstruction process is time consuming so that predicting hemodynamic and structural evolution by computational modeling is unfeasible in routine clinical practice. The aim of the study was to design and develop a parametric program for three‐dimensional (3D) representations of aneurysmal aorta and different BAV phenotypes starting from several measures derived by computed‐tomography angiography (CTA). Assuming that wall shear stress (WSS) has an important implication on bicuspid aortopathy, computational flow analyses were then performed to estimate how different would such an important parameter be, if a parametric aortic geometry was used as compared to standard geometric reconstructions obtained by CTA scans. Morphologic parameters here documented can be used to rapidly model the aorta and any phenotypes of BAV. t‐test and Bland–Altman plot demonstrated that WSS obtained by flow analysis of parametric aortic geometries was in good agreement with that obtained from the flow analysis of CTA‐related geometries. The proposed program offers a rapid and automated tool for 3D anatomic representations of bicuspid aortopathy with promising application in routine clinical practice by reducing the amount of time for anatomic reconstructions.     

Influence of bicuspid valve geometry on ascending aortic fluid dynamics: a parametric study

Bicuspid aortic valve (BAV) predisposes to aortic aneurysms with a high prevalence. A first hypothesis for this phenomenon is related to fibrillin deficiency (genetic hypothesis). The present article focused on a complementary, hemodynamic hypothesis stating that it is the peculiar fluid dynamics of blood in the ascending aorta of patients with BAV configurations that leads to aneurysm formation. To corroborate this hypothesis, a parametric study was performed based on numerical simulations of ascending aorta hemodynamics with different configurations of orifice area and valve orientation. The resulting wall shear stress (WSS) distributions and degree of asymmetry of the blood jet were investigated, and surrogate indices introduced. The results showed that WSS was more pronounced in subjects with BAV morphologies, also in the nonstenotic case. In particular, a maximum WSS of 3Pa was found (vs. 1.5Pa in subjects with a tricuspid configuration). It is localized at the mid-ascending aorta, the segment more prone to dilate as shown by the index related to maximum WSS (0.869 in BAV vs. 0.322 in tricuspid). Moreover, the asymmetry of the blood flow was found larger for decreasing valve area, the related index at mid-ascending aorta being more than three times higher than that found for tricuspid configuration (0.70 vs. 0.20). Further, WSS and flow asymmetry were higher also at the sinus of Valsalva and sinotubolar junction for a latero-lateral (LL) BAV configuration in keeping with the clinical observation on association between BAV configurations and different aortic aneurysm morphology. These findings may help explain the higher risk of aneurysm formation in BAV patients. The proposed indices will require validation prior to application in clinical settings.     

Histologic abnormalities of the ascending aorta and pulmonary trunk in patients with bicuspid aortic valve disease: clinical relevance to the ross procedure.

OBJECTIVE: Bicuspid aortic valve disease is often associated with dilation of the aortic root and ascending aorta. This study examines the histologic features of the ascending aorta and main pulmonary artery of patients with and without aortic valve disease. METHODS: Samples from ascending aorta and main pulmonary artery were obtained at the time of the operation from 20 patients with bicuspid aortic valve and 11 patients with tricuspid aortic valve disease. In addition, samples were also obtained from autopsy cases with normal aortic valve. The histologic changes were graded from 1 to 3 according to severity of degenerative changes. RESULTS: In the ascending aorta, the severity of cystic medial necrosis (P =.001), elastic fragmentation (P =.002), and changes in the smooth muscle cell orientation (P =.002) were significantly more severe in patients with bicuspid than in those with tricuspid aortic valve disease. In the pulmonary trunk specimens, those 3 histologic features were also significantly more severe in patients with bicuspid than those with tricuspid valves (P =.001, P =.01, and P =.04, respectively). Seventy-five percent of patients with bicuspid aortic valve disease had grade 3 degenerative changes, whereas only 14% of those patients with tricuspid aortic valve disease had similar degrees of degenerative changes. CONCLUSION: Patients with bicuspid aortic valve disease have more severe degenerative changes in the media of the ascending aorta and main pulmonary artery than patients with tricuspid aortic valve disease. These findings may explain root and ascending aortic dilation in patients with bicuspid aortic valve disease and pulmonary autograft dilation in certain patients after the Ross procedure.     

Ascending aortic aneurysm associated with bicuspid and tricuspid aortic valve: involvement and clinical relevance of smooth muscle cell apoptosis and expression of cell death-initiating proteins.

OBJECTIVE: There is relationship between a dilated ascending aorta and a bicuspid aortic valve. Controversy exists concerning techniques available for surgical restoration of the functional and anatomical integrity of the aortic root. The present study was undertaken to define the histopathologic and molecular biologic condition of ascending aortic aneurysms associated with bicuspid (BAV) or tricuspid aortic valve (TAV) and the relationship to valve sparing or pulmonary autograft procedures. METHODS: Aortic aneurysm wall specimens from 20 patients (10 BAV; 10 TAV) undergoing elective repair and normal aortic tissues from organ donors (n=5) were analysed for patterns of smooth muscle cells (SMCs) and infiltrating leukocytes (immunohistochemistry), apoptosis (in situ end-labelling of DNA-fragments (TUNEL)), and expression of the death-promoting proteins perforin, Fas, and FasLigand (Immunoblotting). RESULTS: Segments from aneurysms exhibited a distinct pattern of medial destruction, elastic fragmentation, and disorientation with rarefication of SMCs. BAV wall segments contained more cells bearing markers of apoptosis than TAV specimens whereas normal aorta displayed only few apoptotic cells (P<0.05). TUNEL showed higher levels of DNA fragmentation in BAV than in TAV, and double immunostaining identified SMCs as the principal cell type displaying fragmented DNA. Immunohistochemistry confirmed expression of death-promoting mediators by infiltrating lymphocytes, and Western blotting documented their presence in BAV and TAV aneurysmal tissue, with the greatest increases seen in specimens from aneurysms associated with BAV. CONCLUSIONS: There is evidence for a molecular link between SMC apoptosis initiated by infiltration and local signal expression of immune cells and weakening of the aortic wall being more prevalent in patients with BAV. Our findings may suggest a mechanism responsible for aneurysm formation of the aorta and aortic dilatation after autograft root or sinus remodelling procedures.     

Aortic complications after bicuspid aortic valve replacement: long-term results

BACKGROUND: Bicuspid aortic valve (BAV) is a risk factor for aortic dissection and aneurysm. We studied patients with BAV and tricuspid aortic valve (TAV) to evaluate long-term changes in the ascending aorta after aortic valve replacement (AVR). PATIENTS AND METHODS: One hundred consecutive patients were allocated into two groups according to the presence of BAV (group A, 50 patients) or TAV (group B, 50 patients). Mean age was 51 +/- 12 years in group A, and 50 +/- years 12 in group B. No patients had hypertension or Marfan's syndrome. Until July 2001, mean follow-up was 234 +/- 47 months in group A and 241 +/- 43 months in group B. RESULTS: Five patients (10%, CL 5.7 to 13.9) in group A suffered late acute aortic dissection. Acute aortic dissection (5 vs 0, p = 0.0001) and sudden death (7 vs 0, p = 0.0001) occurred more frequently in patients with BAV. All survivors were assessed by echocardiogram. The mean diameter of the ascending aorta was 48.4 mm in group A and 36.8 mm in group B. Three patients in group A were operated on because of ascending aorta aneurysm more than 6 cm in diameter. CONCLUSIONS: As a result of our experience, we recommend a policy of prophylactic replacement of even a seemingly normal and definitely a mildly enlarged ascending aorta in cases of BAV at the moment of AVR, and consideration of a similar approach for any other cardiac surgical procedure in patients with BAV.     

Morphometric analysis of aortic media in patients with bicuspid and tricuspid aortic valve

BACKGROUND: Patients with bicuspid aortic valves tend to develop dilatation of the ascending aorta. The aim of this study was to analyze whether or not there is any histologic difference in the aortic media of patients with a bicuspid aortic valve or a tricuspid aortic valve. METHODS: A morphometric analysis of the wall of the ascending aorta was performed in 107 patients with bicuspid aortic valves undergoing aortic valve operations. The thickness of the elastic lamellae of the aortic media and the distances between the elastic lamellae were measured with the use of an image analysis system. The histologic specimens of the ascending aorta from 61 surgical patients with tricuspid aortic valve disease served as a control. RESULTS: The patients with bicuspid aortic valves had thinner elastic lamellae of the aortic media (2.71 +/- 0.23 microm) of the ascending aortic wall than the patients with tricuspid aortic valve disease (2.83 +/- 0.23 microm) (p = 0.006). The patients with bicuspid aortic valves also had greater distances between the elastic lamellae (27.21 +/- 8.69 microm) of the ascending aortic wall in comparison with the patients with tricuspid aortic valve disease (24.34 +/- 5.32 microm) (p = 0.033). There was no difference in the total thickness of the aortic media between the groups (p = 0.62). CONCLUSIONS: Patients with a bicuspid aortic valve had thinner elastic lamellae of the aortic media and greater distances between the elastic lamellae than patients with a tricuspid aortic valve.     

Patient-specific assessment of hemodynamics by computational fluid dynamics in patients with bicuspid aortopathy

Objective

Hemodynamics related to eccentric blood flow may factor into the development of bicuspid aortic valve aortopathy. We investigated wall shear stress distribution by means of magnetic resonance imaging–based computational fluid dynamics in patients with a bicuspid aortic valve.

Structural and biomolecular changes in aorta and pulmonary trunk of patients with aortic aneurysm and valve disease: implications for the Ross procedure.

OBJECTIVES: A higher incidence of pulmonary autograft dilatation is assumed in patients with ascending aortic dilatation and bicuspid aortic valve disease. To examine whether structural abnormalities are present in the ascending aorta as well as in the pulmonary trunk (PT) we specifically addressed molecular mechanisms and signalling pathways for aneurysm formation in ascending aortic aneurysms and PT of patients with different aortic valve pathology undergoing an extended Ross procedure. METHODS: Wall segments resected from aortic aneurysms (20 patients, 7 bicuspid aortic valves BAV, and 13 tricuspid aortic valves TAV) and from PTs were submitted to analysis of leukocyte infiltration (immunohistochemistry), smooth muscle cell (SMC) apoptosis (in situ end-labelling of DNA-fragments TUNEL), and expression of death-promoting proteins perforin, granzyme B, Fas/FasL (immunoblotting). RESULTS: Degenerative changes including rarefication and apoptosis of SMCs were significantly more severe in BAV than TAV disease (apoptotic index 9.2+/-3.2 vs. 11.9+/-6.2, P = 0.02). Immunohistochemistry confirmed presence and activation of death-promoting mediators in aneurysmal tissue whereas pulmonary tissue displayed only few apoptotic cells, occasional Fas+cells, rarely colocalized with FasL. By Western blot analysis extracts from BAV and TAV but not pulmonary artery wall contained appreciable amounts of perforin, granzyme B, and Fas/FasL. CONCLUSION: Aneurysm formation is associated with SMC apoptosis and local signal expression of activated cells in patients with bicuspid as well as TAV. The PT itself is not pathologically involved with only minor degenerative changes. Although the disease process in the aorta appeared to be more severe in patients with BAV, there was similarity of histological and molecular changes of the pulmonary artery wall in all patients. Dilation of the pulmonary autograft seems not to be the result of histopathological and biomolecular mechanisms in the PT.     

主动脉瓣二瓣畸形与升主动脉形变的血流动力学关系

主动脉瓣二瓣畸形(BAV)是常见的先天性心脏病,BAV与升主动脉形变的血流动力学之间的关系至关重要,本文旨在对其进行综述。     

Aortic Dissecting Aneurysm with a Bicuspid Aortic Valve in Turner's Syndrome: Report of a Case

We herein report the performance of a successful, modified Bentall procedure and a total arch replacement for a Stanford type A chronic aortic dissection and a bicuspid aortic valve in Turner's syndrome (TS). The patient was a 45-year-old woman with 45, XO karyotype TS, who had had a history of hypertension since the age of 20. She had also been diagnosed as having a dilatation of the ascending aorta and a bicuspid aortic valve 3 years earlier. The patient became aware of back pain 6 months prior to the current admission, and was diagnosed as having a Stanford type A chronic aortic dissection and a bicuspid aortic valve with mild aortic regurgitation. One of the greatest concerns in TS is the risk of aortic dissection. Regarding the operation, aortic root replacement is one of the options for a bicuspid aortic valve so as to avoid high-risk surgical procedures in TS.     

Surgical approach to ascending aorta in bicuspid aortic valve

OBJECTIVE: Former studies have pointed out that hemodynamic stress imposed by associated valvular disease is the primary factor in the development of ascending aorta dilatation. At present, intrinsic wall pathology is blamed for dilatation and aneurysm formation in bicuspid aortic valve (BAV). MATERIALS AND METHODS: Aortic valve replacement (AVR) was performed on 78 adult patients with BAV. Patients were divided into two groups. Group I (n = 27) underwent only AVR. Group II (n = 51) underwent AVR and additional ascending aorta procedures such as Shawl-Lapel aortoplasty (n = 12) and tailoring aortoplasty (n = 9). Dacron wrapping was performed after both techniques were done. Ascending aorta replacement was done on 11 patients by using composite graft. Supracoronary graft replacement was performed in 3 patients after AVR. RESULTS: Ascending aorta diameter increment was 1.25 mm/year in normotensive and 2.80 mm/ year in hypertensive patients. Ascending aorta aneurysm (diameter > 55 mm) developed in eight patients in the postoperative period in group I. Ascending aorta dilatation did not develop in group II patients. Mean survival time +/- standard error (SE) was 128 +/- 11 and 99 +/- 4 months and survival possibility was 77.78% and 92.16%. Freedom from reoperation was 65.4% and 95.9% in 8 years in group I and group II, respectively. CONCLUSION: Aortic wrapping with or without aortoplasty has a beneficial effect not only in dilated ascending aorta but also in all nondilated BAV patients with normal-sized aortic diameter. Ascending aorta wrapping in BAV patients preserves the endothelial lining and prevents further dilatation, aneurysm formation, and dissection.     

Matrix metalloproteinase expression in the ascending aorta and aortic valve

Extracellular matrix degradation and increased proteolytic enzyme (matrix metalloproteinase (MMP)) activity characterise abdominal aortic aneurysm formation. Post-stenotic dilatation of ascending aorta is associated with aortic stenosis and regurgitation, haemodynamically normal bicuspid aortic valve (BAV) and following AV replacement. We aimed to determine an association between ascending aortic pathology and abnormal AV, with particular reference to MMPs, and ascertain differences between BAV and tricuspid (TAV) AV. Subset of the study population (n=19) with a preoperative ascending aorta of >4 cm was analysed. Samples of ascending aorta and AV were obtained from 82 patients (TAV, n=54, BAV, n=28) undergoing surgery. Gene expression of MMP-1, -2, -9 and tissue inhibitor of metalloproteinase (TIMP)-1 and -2 was quantified by real-time RT-PCR. No significant difference was seen in gene expression level of MMPs, TIMPs and ratio of MMPs/TIMPs in ascending aorta and AV between patients with BAV and TAV. MMP-2/TIMP-1 in ascending aorta was greater in BAV, in the subset of patients with preoperative aortic dilatation (P<0.05). No difference exists in gene expression of MMPs in ascending aorta and AV between patients with BAV and TAV. However, patients with larger aortic diameters have increased MMP-2/TIMP-1. Modifying MMP expression may have a role in development of aneurysms.     

Bicuspid aortic valve and aortic dilation: The current understanding

Aim: The bicuspid aortic valve (BAV) is one of the most common congenital heart disorders affecting 1–2% of the population. Individuals with a BAV tend to develop ascending aortic dilation, and are believed to be at high risk of aortic rupture and dissection. The association between the BAV and aortic stenosis, aortic regurgitation or infective endocarditis has been previously described, leading to the hypothesis of a common developmental anomaly incorporating both the aortic valve and thoracic aorta, and requires genetic solutions. The present article aims to make a comprehensive review of the possible determinants of this congenital defect entity. Methods: A literature retrieval was made by using the search terms ‘bicuspid aortic valve’ and ‘aortic dilation’ or ‘aortic aneurysm’ in major medical databases, including EMBASE, Cochrane Library, LILACS, MEDLINE and ADOLEC. A total of 496 articles were obtained. Relevant studies in the aetiologies of the BAV on the basis of clinical observations and basic research were selected and analysed. Results: Results from clinical observations have taken a haemodynamically resultant aortic dilation in the presence of a BAV into consideration. The two pathogenetic factors, haemodynamic and genetic, might coexist. Each of them could in turn prevail in different clinical pictures or anatomical forms. The presence of medial degeneration, elastic fragmentation and changes in smooth muscle cells was found to be much more severe in patients with a BAV than in those with a tricuspid aortic valve. Determination of the apoptotic index showed significantly increased numbers of dead smooth muscle cells in aneurysmal sections when compared with the normal aorta. Mean endothelial nitric oxide synthase levels in the endothelial cells of the aortic wall in patients with a BAV were significantly lower compared with those with a tricuspid aortic valve. Of importance are the novel findings of extracellular matrix degradation in terms of matrix metalloproteinase and their inhibitors, as well as mutations of variable genes, including Notch1, NKX2.5, ubiquitin fusion degradation 1-like gene and KCNJ2, that have drawn particular attention in the hope of offering an evolutionary explanation of this disorder. Conclusion: The development of the BAV might have diverse molecular triggers, thus it might be difficult to characterize the inciting events that result in a BAV and aortic wall disorders. Extracellular matrix dysregulation and cell death pathways are regarded as important molecular mechanisms of the aortopathy. Matrix degradation and gene mutations are the preferred hypotheses accounting for the development of this congenital lesion.     

Unicuspid Aortic Valve in Patients Undergoing the Ross Procedure

BackgroundThe prevalence and outcomes of the unicuspid aortic valve (UAV) in patients undergoing the Ross procedure have been strongly underreported in the current literature. We sought to evaluate this in comparison with bicuspid (BAV) and tricuspid valve (TAV) in our Ross cohort.MethodsThis was a retrospective observational study of patients undergoing the Ross procedure at 2 dedicated centers between 2009 and 2020. Primary end points were the risks of midterm autograft reoperation and the onset of at least moderate aortic regurgitation during follow-up. The secondary end point was to compare the perioperative outcomes between the groups.ResultsIncluded in the analysis were 286 patients, of those 39% with UAV, 52% with BAV, and 9% with TAV. UAV patients were operated on at the youngest age (P < .001) and more often for a combined hemodynamic aortic valve pathology (P = .02). They had the largest aortic root dimensions: annulus (P = .01), Valsalva sinuses (P = .11), sinotubular junction (P = .001), and ascending aorta (P < .0001). The risks of reoperation (P = .86) and the onset of aortic regurgitation (P = .75) were comparable among the groups over the follow-up of 4.1 years. There was no difference in perioperative outcomes.ConclusionsUAV is a separate unit characterized by a distinct hemodynamic pathology and generated aortopathy. It is not associated with a higher risk of reoperation or new onset of aortic regurgitation after the Ross procedure in the midterm postoperatively. At the current state, UAV remains acceptable for the Ross procedure.     

Hydrodynamics of Aortic Cannulae During Extracorporeal Circulation in a Mock Aortic Arch Aneurysm Model

This study was designed to analyze flow pattern, velocity, and strain on the aortic wall of a glass aortic arch aneurysm model during the extracorporeal circulation, and to elucidate the characteristics of flow pattern in three different aortic cannulae. Different patterns of large vortices and helical flow were made by each cannula. With the curved end‐hole cannula, the high velocity flow (～0.6–0.8 m/s) was blowing to the aneurismal wall without attenuating the strain rate tensor (～0.2–0.25/s). With the dispersion cannula and the Soft‐Flow cannula, cannular jet was attenuated in the ascending aorta creating a large vortex at a velocity less than 0.5 m/s, and the strain rate tensor on the aneurismal wall was small (less than 0.15/s). In conclusion, end‐hole cannula should not be used in the operation of aortic arch aneurysm. Dispersion‐type aortic cannulae were less invasive on the aortic arch aneurismal wall, but particular attention to alternative cannulation sites should be paid in cases with severe atherosclerosis on the ascending aortic wall.     

Aortic root replacement in cardiac dextroversion

Adult cardiac surgery in patients with malrotation of the heart is rare. A 60 year-old lady, with known cardiac dextroversion, presented with dyspnoea and pre-syncopal attacks. Echocardiographical and radiological investigation confirmed the dextroversion, with clockwise rotation of the heart through its longitudinal axis. This resulted in the right ventricular outflow tract and pulmonary artery being wrapped anteriorly around the aorta, with posterior displacement of the right atrium. The presence of a heavily calcified, bicuspid aortic valve and dilated ascending aorta was also demonstrated. At surgery, venous cannulation was established by rotating the heart anticlockwise and access to the aortic valve gained with a more superior oblique aortotomy. In the presence of a dilated ascending aorta with a calcified, bicuspid aortic valve, the aortic root was replaced with a valved conduit. To the authors' knowledge, this is the first report of an aortic root replacement in a patient with cardiac dextroversion.     

Pulmonary artery aneurysm with ascending aortic aneurysm concomitant with bilateral bicuspid semilunar valves

Aneurysm of both the pulmonary trunk and the ascending aorta concomitant with bilateral bicuspid valves is very rare. The reason for the formation of aneurysm with bicuspid semilunar valve is still inconclusive. Surgical repair was performed successfully (ie, aortic valve replacement, graft replacement for the ascending aorta, and plication of the pulmonary artery). Pathology of the pulmonary artery wall did not demonstrate cystic medial necrosis. The hemodynamic turbulence by the bilateral bicuspid valve may cause the formation of aneurysms even at low pressure. This case demonstrates an explanation for aneurysm with the bicuspid valve.