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• W2752282089 abstract "HomeCirculation: Cardiovascular ImagingVol. 10, No. 9Bicuspid Aortic Valve Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissionsDownload Articles + Supplements ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toSupplementary MaterialsFree AccessReview ArticlePDF/EPUBBicuspid Aortic ValveWhat to Image in Patients Considered for Transcatheter Aortic Valve Replacement? William K.F. Kong, MD, Victoria Delgado, MD, PhD and Jeroen J. Bax, MD, PhD William K.F. KongWilliam K.F. Kong From the Department of Cardiology, Leiden University Medical Center, The Netherlands (W.K.F.K., V.D., J.J.B.); and Department of Cardiology, National University Heart Center, National University Health System, Singapore (W.K.F.K.). Search for more papers by this author , Victoria DelgadoVictoria Delgado From the Department of Cardiology, Leiden University Medical Center, The Netherlands (W.K.F.K., V.D., J.J.B.); and Department of Cardiology, National University Heart Center, National University Health System, Singapore (W.K.F.K.). Search for more papers by this author and Jeroen J. BaxJeroen J. Bax From the Department of Cardiology, Leiden University Medical Center, The Netherlands (W.K.F.K., V.D., J.J.B.); and Department of Cardiology, National University Heart Center, National University Health System, Singapore (W.K.F.K.). Search for more papers by this author Originally published6 Sep 2017https://doi.org/10.1161/CIRCIMAGING.117.005987Circulation: Cardiovascular Imaging. 2017;10:e005987Clinical VignetteA 78-year-old patient presented with New York Heart Association functional class II dyspnea complaints and suspected aortic stenosis. The patient was referred for transthoracic echocardiography which confirmed the presence of severe aortic stenosis secondary to a calcified (probably) bicuspid aortic valve (BAV) with a mean gradient of 22 mm Hg, peak gradient of 40 mm Hg, and calculated aortic valve area of 0.9 cm2 (Figure 1). The stroke volume was 34 mL/m2 (body surface area, 1.68 m2), and the left ventricular ejection fraction was 39%. On computed tomography (CT), the diagnosis of BAV was confirmed, whereas the aortic root and tubular part of the ascending aorta were slightly dilated (sinus of Valsalva, 42 mm; sinotubular junction, 39 mm; tubular ascending aorta, 42 mm; Figure 1). The logistic EuroSCORE II was 16%. Invasive coronary angiography excluded obstructive coronary artery disease needing revascularization. With the diagnosis of classical low-flow, low-gradient, severe aortic stenosis, the patient was referred for transcatheter aortic valve replacement (TAVR) after discussion in the Heart Team.Download figureDownload PowerPointFigure 1. Clinical vignette. A, Left ventricular parasternal long-axis view with calcified aortic valve and dilated aorta. The anatomy of the aortic valve cannot be well defined on parasternal short-axis view (B). Color flow Doppler on the apical 5-chamber view shows turbulent systolic flow through the aortic valve (C). On continuous wave Doppler, the peak velocity was 3 m/s, mean gradient 22 mm Hg and peak gradient 40 mm Hg (D). The calculated stroke volume on pulsed wave Doppler was 34 mL/m2 (E). On computed tomography, the flying-through view shows calcified bicuspid aortic valve with 2 cusps and 2 commissures and tight aortic valve area (arrows, F). This is also demonstrated in the reconstructed short-axis view (G). H, Sagittal view of dilated aorta at the level of the sinuses of Valsalva, sinotubular junction, and ascending aorta.BAV is the most common congenital valvular heart defect, with a prevalence as high as 2% of the general population.1 Among patients undergoing surgical aortic valve replacement for aortic stenosis, BAV can be present in as high as 49% of patients with 9% older than 80 years.2 Currently, TAVR is an established therapy for patients with symptomatic severe aortic stenosis with high risk or contraindications for surgery. Landmark randomized trials have considered BAV as an exclusion criterion. However, large registries have shown that a significant number of patients with BAV have been treated with TAVR (Figure 2).3-5 Compared with tricuspid aortic valve stenosis, TAVR in BAV stenosis has been associated with higher rates of paravalvular regurgitation, 30-day mortality rates, and likelihood of conversion to surgery.6 New TAVR generation devices have been associated with lower rates of paravalvular regurgitation.7 Implementation of CT to assess the geometry and dimensions of the aortic annulus has improved prosthesis sizing, thereby reducing the risk of paravalvular regurgitation or annulus rupture.8 However, BAV is a heterogeneous disease with varying valve morphology (raphe versus nonraphe; asymmetrical cusp size), annulus geometry and size, asymmetrical calcification of the aortic valve and left ventricular outflow tract, frequently associated with anomalous origin of coronary arteries and various configurations of aortic root and ascending aorta that may challenge TAVR. In this specific group of patients, multimodality imaging is crucial for patient selection and choice of the most appropriate device to ensure procedural success (Table).Table. Key Features of Bicuspid Aortic Valve Stenosis Patients to be Evaluated Before Transcatheter Aortic Valve ReplacementParameterImaging TechniqueAortic valve morphology Valve configuration Presence of raphe Orientation of cuspsEchocardiography MDCT MRI Valve calcification Raphe (complete vs incomplete) Commissures Symmetrical/asymmetricalEchocardiography MDCTAssessment of aortic valve function Aortic valve stenosis Aortic valve regurgitationEchocardiography MDCT MRIAortic annulus geometry and dimensionsMDCT 3D TEE MRIAortic root and ascending aorta Aortic dimensions: sinus of Valsalva, sinotubular junction and ascending aorta Aortopathy Horizontal aortaEchocardiography MDCT MRICoronary arteries: height and location of ostia Anomalous coronary anatomyMDCTImplications for prosthesis type selectionMDCTThe imaging techniques are ordered according to the availability and feasibility. 3D indicates 3-dimensional; MDCT, multidetector row computed tomography; MRI, magnetic resonance imaging; and TEE, transesophageal echocardiography.Download figureDownload PowerPointFigure 2. Prevalence of bicuspid aortic valve in transcatheter aortic valve replacement registries. BAV indicates bicuspid aortic valve; and TAV, tricuspid aortic valve. GARY indicates German TAVI registry; and STS/ACC TVT, Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy.In this review article, we aim to provide a detailed roadmap (using the 6 points put forward in Table) for the use of multimodality imaging to select patients with BAV stenosis for TAVR.Aortic Valve MorphologyValve ConfigurationA BAV is defined by the presence of 2 commissures in systole. However, the morphology of BAV is highly variable ranging from valves with 2 cusps and 2 commissures to valves with 3 cusps fused by 1 or 2 raphes that leave 2 or 1 commissures, respectively (Figure 3). The completeness of the fusion raphe varies, and there may be incomplete raphes that challenge the diagnosis of the valve morphology. Cusp number and size, cusp position, number of commissures, and characteristics of aortic sinus and interleaflet triangles have been used to classify the BAV.1 The classification of Sievers and Schmidtke,9 based on surgical specimen, is frequently used (Figure 3; Movie I in the Data Supplement). Using the number of raphes, the BAV can be classified as type 0 (without raphe), type 1 (1 raphe), and type 2 (2 raphes). Within each category, the BAV phenotype was classified further based on the following criteria: the spatial position of the cusps and commissures (anteroposterior versus lateral) and valvular function (graded as predominantly regurgitation, predominantly stenosis, balanced regurgitation and stenosis, or no stenosis or regurgitation).9Download figureDownload PowerPointFigure 3. Schematic representation of various bicuspid aortic valve (BAV) morphologies according to the Sievers classification.9 The aortic valve is depicted on a cross-sectional short-axis view. The origin of the right coronary artery (RCA) and the left main (LM) are demarcated with red lines. An echocardiographic example of each type is presented at the bottom. Type 0: BAV without raphe, with lateral or anteroposterior orientation of the free edge of the cusps. The echocardiographic example shows a BAV with lateral morphology. Type 1: BAV with 1 raphe (in black), the most frequent type with fusion of the right (R) and left (L) coronary cusps followed by fusion of the right and noncoronary (N) cusps. The echocardiographic example shows a BAV with LR fusion (the arrow indicates the raphe). Type 2: BAV with 2 raphes. The transesophageal echocardiographic example shows 2 fusion raphe (arrows).Echocardiography is the imaging technique of choice to diagnose and characterize BAV. However, in patients who may be a candidate for TAVR, the presence of severe, bulky calcifications of the valve may challenge the diagnosis. Compared with CT, echocardiography has a lower accuracy to detect BAV.10 Multidetector row CT (MDCT) is pivotal in the work-up for TAVR, and, based on the large variability in BAV configurations observed in a CT core laboratory, a new classification of BAV has been proposed.8 This new classification takes into consideration the aortic valve morphology and its interaction with the deployed transcatheter valve at the aortic cusp plane (presence or absence of raphe) and at the commissural level (presence of 2 or 3 commissures; Figure 4). Tricommissural BAV (traditionally known as acquired or functional BAV) is characterized by 3 cusps with focal fusion of 3 commissures. Bicommissural raphe type is characterized by the presence of a true raphe, whereas the bicommissural nonraphe type has 2 cusps and 2 commissures. In addition, based on the leaflet orientation, the BAV is further classified as coronary cusp fusion (when the coronary arteries arise from the coronary sinuses of 2 fused cusps) and mixed cusp fusion (when the noncoronary cusp is fused with the left or the right coronary cusps and the coronary arteries arise from 2 independent coronary sinuses).Download figureDownload PowerPointFigure 4. Classification of bicuspid aortic valve based on computed tomography in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement (TAVR). A, A tricommissural, functionally bicuspid aortic valve. A bicommissural raphe-type bicuspid aortic valve is presented in B. The arrow indicates the calcified raphe between the left and right coronary cusps. C, A bicommissural nonraphe-type bicuspid aortic valve.Valve CalcificationCardiac CT is the imaging technique of reference to assess aortic valve calcification. In patients aged ≥80 years old, a study evaluating the characteristics of operatively excised stenotic valves showed that BAVs are heavier than tricuspid valves in men (3.61 versus 2.31 g) and women (2.62 versus 1.64 g), suggesting that the deposition of calcium and fibrotic tissue is higher in BAV.11 The calcifications are most frequently observed in the cusps and raphe as viewed from the aortic side. The calcification of the aortic cusps is usually asymmetrical and the most often involved cusp is the left.12 The amount and distribution of valve calcifications may pose challenges to transcatheter valve deployment. However, the new-generation devices have overcome the unfavorable anatomy of BAV. A recent large multicenter registry of TAVR in BAV patients has shown that the incidence of significant paravalvular regurgitation has decreased compared with the early-generation valves (from 8.5% to 0%; P<0.001).7Assessment of Aortic Valve FunctionAortic Valve StenosisAortic stenosis is the most common complication of BAV. In a large series of excised stenotic aortic valves, bicuspid anatomy was present in 59% of patients aged ≤70 years and 41% of patients older than 70 years.13 In contrast, aortic regurgitation is less frequently observed (43% of BAV patients undergoing aortic valve surgery).14Aortic stenosis is routinely assessed with transthoracic echocardiography, and the severity is based on peak jet velocity, mean transvalvular gradient, and effective orifice area calculated according to the continuity equation.15 A peak jet velocity >4 m/s, mean gradient >40 mm Hg, and aortic valve area <1 cm2 define severe aortic stenosis. However, a subgroup of patients may show inconsistently graded severe aortic stenosis: a tight aortic valve area but a low transvalvular gradient. This may relate to impaired left ventricular systolic function (classical low-flow, low-gradient, severe aortic stenosis) or reduced stroke volume in patients with a severely hypertrophied left ventricle and restrictive physiology or because of the presence of severe mitral valve disease (paradoxical low-flow, low-gradient, severe aortic stenosis). In addition, erroneous measurements of the left ventricular outflow tract diameter may result in a tight aortic valve area with a low gradient regardless of left ventricular ejection fraction.16 The prevalence of inconsistently graded severe aortic stenosis among patients with BAV has not been reported. It is speculated that the asymmetrical distribution of valve calcification may lead to eccentric jets that challenge the alignment of the ultrasound beam and lead to underestimation of transvalvular gradients on continuous wave Doppler echocardiography. On the other hand, the left ventricular outflow tract in patients with BAV is significantly larger than in patients with tricuspid aortic valve. This may lead to a lower proportion of patients with discordantly graded severe aortic stenosis. Three-dimensional imaging techniques can aid in the identification of severe aortic stenosis. By aligning the multiplanar reformation planes across the tips of the aortic cusps, the anatomic aortic valve area can be accurately measured (Figure 5). In addition, by incorporating the planimetered cross-sectional area of the left ventricular outflow tract obtained with 3-dimensional imaging techniques into the continuity equation, the grading of the aortic stenosis may change from severe to moderate.16,17 In patients with tricuspid severe aortic valve stenosis and preserved left ventricular ejection fraction, 33% of patients with low gradient would have been classified to moderate aortic stenosis if the MDCT derived left ventricular outflow tract area would have been included in the continuity equation.16 However, a recent study showed that an aortic valve area ≤1.2 cm2 measured on MDCT had similar prognostic value as an aortic valve area ≤1 cm2 and suggested that the cutoff value to define severe aortic stenosis should be different based on the imaging method used.17Download figureDownload PowerPointFigure 5. Severe aortic stenosis: effective vs anatomic aortic valve area. The anatomic aortic valve area may be challenging to measure from the parasternal short-axis view in patients with severe bicuspid aortic valve (BAV) stenosis (A). The aortic transvalvular peak (113 mm Hg) and mean (69 mm Hg) gradients are obtained by continuous wave Doppler across the bicuspid aortic valve (B). On pulsed wave spectral Doppler the signal of the left ventricular outflow tract, the velocity time integral, is obtained and used along with the aortic valve velocity time integral obtained on continuous wave Doppler to calculate the aortic valve area by the continuity equation (0.4 cm2, C). The valve morphology can be better visualized with 3-dimensional transesophageal echocardiography using the biplane view that provides the long-axis view of the valve (D) and the short-axis view of the aortic valve at the level of the tips of the cusps (E). However, in severely calcified valves, the calcifications create shadow on the edge of the cusps challenging the measurement of the anatomic valve area. On computed tomography, the anatomic aortic valve area can be assessed accurately (0.6 cm2, F).Finally, the calcium load of the aortic valve as assessed with CT has been proposed as surrogate to grade aortic stenosis. For the same age and sex, it is well established that BAV has a larger calcium load than tricuspid aortic valves.12 In addition, in patients older than 51 years, increasing aortic valve calcium load is significantly correlated with a higher mean transvalvular gradient.18 However, the optimal threshold of aortic valve calcium load to define severe aortic stenosis in BAV has not been defined. How these novel imaging techniques may influence on the grading of aortic stenosis in BAV remains to be investigated.Aortic RegurgitationIn BAV stenosis, mild or moderate aortic regurgitation is frequently present. The measures of aortic stenosis severity remain accurate even when aortic regurgitation is severe. However, for a given aortic valve area, the peak velocity and mean transvalvular gradient may be higher than expected because of the high transaortic volume flow rate.19 Echocardiographic assessment of aortic regurgitation severity relies on color, continuous and pulsed wave Doppler parameters of the regurgitant jet along with evaluation of left ventricular volumes and function.20 Color flow Doppler permits visual assessment of the regurgitant jet and informs about jet eccentricity. The ratio between the regurgitant jet width and the left ventricular outflow tract diameter is a semiquantitative parameter of aortic regurgitation severity. However, it assumes a circular regurgitant orifice which is not applicable in BAV anatomy. Therefore, this parameter should not be used in isolation in BAV aortic regurgitation. Instead, vena contracta width and quantification of the effective regurgitant orifice area and regurgitant volume with the proximal isovelocity surface area method are recommended to grade aortic regurgitation.20 Although the vena contracta width can be applied to eccentric regurgitant jets, the feasibility of the proximal isovelocity surface area method is limited. The use of 3-dimensional imaging techniques such as echocardiography and cardiovascular magnetic resonance may improve the quantification of the effective regurgitant orifice area and the regurgitant volume (Figure 6).21 Finally, the measurement of the diastolic flow reversal in the descending aorta using pulsed wave Doppler recordings is a strong parameter to define severe aortic regurgitation. However, it may be affected by the aortic compliance and whether it concerns an acute or chronic regurgitation.Download figureDownload PowerPointFigure 6. Assessment of bicuspid aortic regurgitation. Example of a 65-y-old male with a severely calcified bicuspid aortic valve, with severe stenosis and moderate regurgitation. A, The short-axis view of the aortic valve on transesophageal echocardiography. On surgical inspection, there was a raphe between the left (LCC) and the right coronary cusps (RCC; asterisk). The 3-dimensional reconstruction of the aortic valve is shown in B. From the transgastric view, the regurgitant jet can be visualized and the vena contracta measured (6 mm, C). The continuous wave Doppler spectral signal of the regurgitant jet is shown in D. The pressure half-time was 323 ms (indicating moderate aortic regurgitation). The measurement of the systolic transvalvular gradient on continuous wave Doppler indicates severe aortic stenosis with a mean gradient of 87 mm Hg, probably increased due to the severity of aortic regurgitation. The measurement of the systolic transvalvular gradient on continuous wave Doppler indicates severe aortic stenosis with a mean gradient of 87 mm Hg in E, probably increased due to the severity of aortic regurgitation. F, The orthogonal multiplanar reformation planes reconstructed from 3-dimensional color Doppler echocardiographic data of the regurgitant jet. NCC indicates non-coronary cusp.Aortic Annulus Geometry and DimensionsAccurate preoperative assessment of the aortic annular dimensions is crucial for the success of TAVR because the choice of an incorrectly sized prosthesis may result in complications such as severe paravalvular regurgitation, prosthesis migration, and annulus rupture. According to current recommendations, the choice of prosthesis size is based on MDCT or 3-dimensional transesophageal echocardiography if MDCT is not feasible.15 BAV is characterized by a larger annulus size and sinus of Valsalva with increased ascending aorta dimensions, when compared with tricuspid aortic valves. In addition, the BAV aortic annulus is less elliptical than the tricuspid valve annulus and shows more frequently eccentric calcifications.22 In tricuspid aortic valves, the aortic annulus is commonly defined as the plane bisecting the most basal attachment points of the 3 cusps into the left ventricular outflow tract. However, with BAV anatomy, the 3 points that demark the annulus plane may be difficult to define. Particularly, in type 0 BAV, there are only 2 hinge points of the 2 existing cusps. The third point to define the annular plane will be derived from a plane perpendicular to the landing zone of the prosthesis (Figure 7). Conversely, in type 1 BAV, the hinge points of the 3 cusps can be identified and the annulus plane can be defined conventionally (Figure 7). To date, there is no established methodology to define the aortic annulus plane in BAV. In type 0 BAV, it could be hypothesized that the area enclosed between the commissures and the cusps in systole should be the area to be covered by the deployed transcatheter valve. However, in patients with severe BAV stenosis, this area may be difficult to determine, which can result in significant undersizing. In addition, there is little and inconsistent evidence on how the prosthesis frame is deployed in large cohorts of patients with BAV stenosis. In 11 patients with type 0 BAV (as assessed with transesophageal echocardiography) who received a balloon-expandable prosthesis, Wijesinghe et al23 reported a circular deployment of the prosthesis frame in all patients. In contrast, Himbert et al24 reported an elliptical deployment of the prosthetic frame as assessed with MDCT in 15 patients with BAV stenosis (most of them with type 1 BAV) who received a self-expandable prosthesis. Similarly, Hayashida et al25 described an elliptical deployment of the prosthetic frame in 21 BAV stenosis patients (86% type 1 and 14% type 2, with 2 raphe) receiving a self-expandable (50%) or balloon-expandable (50%) prosthesis. The presence of a much calcified, thickened raphe may limit the deployment of the prosthetic frame. In addition, it remains unknown whether the deployment of the frame is homogeneous or more restrained at the level of the edge of the native aortic cusps when compared with the level of the annular plane. These observations suggest that the definition of the aortic annulus plane and measurement of the aortic annulus size are not the only factors to take into consideration when selecting the prosthesis type and size. Probably, the interaction between the BAV anatomy and the prosthesis type is more important for the final TAVR results than just the size of the aortic annulus. The landing zone that spans between the edges of the cusps until the left ventricular outflow tract should be considered, including the presence or absence of raphe and the calcium load (thickness) of the raphe.Download figureDownload PowerPointFigure 7. Assessment of aortic annulus dimensions with multidetector row computed tomography according to the type of bicuspid aortic valve (BAV). A, An example of type 0 BAV. The hinge points of the 2 cusps into the left ventricular outflow tract can be demarcated (arrows in the coronal plane—upper, left), whereas the third point will be derived from a plane perpendicular to the landing zone of the prosthesis (red line in the lower, left). In B, the measurement of the aortic annulus of a type 1 BAV is presented. In this type of BAV, the hinge points of the right (red point), left (green point), and no-coronary (yellow point) cusps can be identified and the orthogonal planes cross the hinge points of the cusps (yellow arrows in the coronal plane—upper, left; red arrow in the sagittal plane—lower, left).Aortic Root and Ascending AortaAortopathyBAV disease is not just confined to the valve cusps; the aorta is also abnormal, a condition known as bicuspid aortopathy, observed in ≈35% to 50% of patients.26 Compared with adults with a tricuspid aortic valve, BAV patients have larger dimensions of the aortic sinuses and ascending aorta and are at risk for progressive aortic dilation because of abnormal aortic elasticity.27 The average annual increase in aortic diameter ranges from 0.2 to 1.2 cm/y. The presence of a family history of aortic valve disease has shown to be significantly associated with increased risk of aortic dilation.28 In addition, after aortic valve replacement, the thoracic aorta may continue to dilate and the risk of late dissection does not disappear.29–31 Therefore, in patients with severe BAV stenosis and aortic dilation, the decision to perform TAVR without repairing the aorta should be weighed against the risk of aortic aneurysm formation and late aortic dissection.Several patterns of aortic dilation have been described (Figure 8).32 Transthoracic echocardiography is the primary diagnostic tool for evaluation of BAV patients; however, it is unable to evaluate the entire ascending and descending aorta. Transesophageal echocardiography permits better definition of the aortic root and ascending aorta dimensions. However, this imaging modality is relatively invasive and is not suitable for patient surveillance. CT and magnetic resonance imaging are considered the reference standard to measure the aortic dimensions at different levels.Download figureDownload PowerPointFigure 8. Type of bicuspid aortopathy. Type 1 aortopathy (isolated aortic root involvement with normal tubular ascending aorta and arch dimensions) is shown in A. Type 2 aortopathy is characterized by involvement of tubular ascending aorta but sparing of the aortic root (B). Diffuse dilation of aortic root with involvement of the ascending aorta and aortic arch (Type 3) is shown in C.Current guidelines recommend aortic surgery in patients with BAV and an aortic diameter ≥55 mm; however, aortic surgery should be considered in patients with BAV and an aortic diameter ≥50 mm and additional risk factors (coarctation of the aorta, systemic hypertension, family history of dissection, or increase in aortic diameter 0.3 mm/y).15 Recently, a cross-sectional area:height ratio >10 cm2/m measured at the level of the sinus of Valsalva or at the tubular ascending aorta has been associated with increased risk of type A dissection.33The presence of bicuspid aortopathy increases the risk of aortic dissection and rupture during balloon valvuloplasty or implantation of balloon-expandable valves. However, the true incidence of aortic complications in BAV patients remains unknown. It would be interesting to know whether a specific type of aortopathy may entail a higher complication risk during TAVR. In addition, the progression to aortic aneurysm and occurrence of late aortic dissection after TAVR have not been reported.34 It may be difficult to demonstrate if these complications occurred in current series of BAV patients treated with TAVR because the frequency is relatively low (3%–9% for aortic aneurysm formation and 0.5%–1% for aortic dissection).29,31 In addition, these complications have been described over a mean follow-up of at least 10 years, but TAVR is a relatively new therapy and experiences with at 10 years of follow-up are anecdotal.29,31Horizontal AortaOne of the characteristics of patients with BAV stenosis is the presence of a horizontal aorta defined as an angle of <30° between the plane perpendicular to the aortic annulus plane and a horizontal reference line (Figure 9). A horizontal aorta may complicate accurate positioning of the prosthesis during TAVR, particularly when using a self-expanding valve. Need of a second valve and postdilation, longer fluoroscopy time and increased device embolization, and mild or greater than mild paravalvular regurgitation have been described.35 Accordingly, balloon-expanding valves may be preferred in patients with BAV stenosis and horizontal aorta. Moreover, calcified aortic wall (porcelain aorta) is more frequent in horizontal aortas. The presence of significant calcifications of the ascending aorta limits the capability to control the tension on the delivery catheter during the device release and may lead to implantation failure.36 Therefore, delivery through the transfemoral or transaxillary/subclavian routes may increase the risk of aortic dissection or distal embolization. For this reason, the transapical route often is selected in these cases. MDCT imaging of the aortovalvular complex has become a prerequisite for procedural planning with self-expanding TAVR in patients with horizontal aorta.Download figureDownload PowerPointFigure 9. Horizontal aorta in bicuspid aortic valve. Examples of 2 patients with bicuspid aortic valve stenosis evaluated for transcatheter aortic valve replacement. Horizontal aorta is defined as an angle of <30° between the plane perpendicular to the aortic annulus plane and a horizontal reference line. In A, the angle is 29.7° indicating the presence of horizontal aorta, whereas, in B, the angle is 40°.Coronary Arteries: Height and Location of OstiaThe presence of significant coronary artery stenosis should be evaluated with invasive coronary angiography before TAVR. However, to assess the risk of occlusion of the coronary ostia by one of the aortic cusps during TAVR, MDCT provides better spa" @default.
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