Coronary Obstruction in Transcatheter Aortic Valve-in-Valve Implantation
2015; Lippincott Williams & Wilkins; Volume: 8; Issue: 1 Linguagem: Inglês
10.1161/circinterventions.114.002079
ISSN1941-7632
AutoresDanny Dvir, Jonathon Leipsic, Philipp Blanke, Henrique Barbosa Ribeiro, Ran Kornowski, Augusto D. Pichard, J Rodés-Cabau, David A. Wood, Dion Stub, Itsik Ben‐Dor, Gabriel Maluenda, Raj Makkar, John G. Webb,
Tópico(s)Cardiac pacing and defibrillation studies
ResumoHomeCirculation: Cardiovascular InterventionsVol. 8, No. 1Coronary Obstruction in Transcatheter Aortic Valve-in-Valve Implantation Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissionsDownload Articles + Supplements ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toSupplemental MaterialFree AccessResearch ArticlePDF/EPUBCoronary Obstruction in Transcatheter Aortic Valve-in-Valve ImplantationPreprocedural Evaluation, Device Selection, Protection, and Treatment Danny Dvir, MD, Jonathon Leipsic, MD, Philipp Blanke, MD, Henrique B. Ribeiro, MD, Ran Kornowski, MD, Augusto Pichard, MD, Joseph Rodés-Cabau, MD, David A. Wood, MD, Dion Stub, PhD, Itsik Ben-Dor, MD, Gabriel Maluenda, MD, Raj R. Makkar, MD and John G. Webb, MD Danny DvirDanny Dvir From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Jonathon LeipsicJonathon Leipsic From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Philipp BlankePhilipp Blanke From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Henrique B. RibeiroHenrique B. Ribeiro From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Ran KornowskiRan Kornowski From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Augusto PichardAugusto Pichard From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Joseph Rodés-CabauJoseph Rodés-Cabau From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , David A. WoodDavid A. Wood From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Dion StubDion Stub From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Itsik Ben-DorItsik Ben-Dor From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Gabriel MaluendaGabriel Maluenda From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). , Raj R. MakkarRaj R. Makkar From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). and John G. WebbJohn G. Webb From the Department of Cardiology, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada (D.D., J.L., P.B., D.A.W., D.S., J.G.W.); Department of Cardiology, Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada (H.B.R., J.R.-C.); Department of Cardiology, Rabin Medical Center, Petach Tikva, Israel (R.K.); Department of Cardiology, Medstar Washington Hospital Center, DC (A.P., I.B.-D.); Department of Cardiology, Cardiovascular Center, Hospital San Borja Arriaran, Santiago, Chile (G.M.); and Department of Cardiology, Cedars-Sinai Heart Institute, Los Angeles, CA (R.R.M.). Originally published15 Jan 2015https://doi.org/10.1161/CIRCINTERVENTIONS.114.002079Circulation: Cardiovascular Interventions. 2015;8:e002079The majority of surgical heart valves being implanted during the past decade are bioprosthetic, tissue valves with limited durabiity.1–4 These tissue valves have limited durability.2–4 Recently, implantation of transcatheter valves inside failed surgically implanted aortic bioprostheses (valve-in-valve [VIV]) has been reported as a less-invasive alternative to repeat surgery.5 Although procedural success is achieved in the great majority of patients, this therapy is associated with several potential risks, including ostial coronary occlusion.6,7Coronary obstruction is a serious procedural complication, associated with a high mortality rate.5–9 Importantly, during the recent years, several preprocedural and technical aspects have been described to identify those patients at increased risk. Therefore, in such high-risk patients, a modified VIV procedure, redo surgical valve replacement, or medical treatment only may be considered (Figure 1). We herein review the mechanisms of coronary obstruction, the optimal identification of patients at risk for coronary obstruction, and further describe technical considerations for preventing and treating this life-threatening complication.Download figureDownload PowerPointFigure 1. Flow chart of suggested evaluation and treatment of a candidate for aortic Valve-in-Valve implantation. (1) Details in Tables 1 to 3. (2) According to imaging and clinical characteristics. (3) Balloon valvuloplasty will optimally model the risk for coronary occlusion using a balloon size similar to the transcatheter heart valve (THV) device to be implanted. The risk for hemodynamic instability after valvuloplasty secondary to worsening regurgitation should be considered, and a THV device should be prepared for rapid implantation if needed. (4) If the patient is hemodynamically stable after valvuloplasty and the risk for left main occlusion seems high, considerations for redo surgery or medical treatment only could be made, otherwise coronary protection is advocated using a wire and a stent. (5) Consider using a retrievable THV device or a device with a leaflet clipping mechanism. (6) Obtain several angiographic pictures from different pictures, while the guide is withdrawn, to evaluate for obstruction before wire and stent removal. (7) Emergent surgical revascularization could be considered if percutaneous approach is not successful. (8) Because coronary obstruction occasionally has delayed presentation and could be only partial or intermittent, all valve-in-valve cases considered high risk for coronary obstruction should have focused clinical, ECG, and echocardiographic evaluation for related symptoms or signs of myocardial ischemia. In selective cases, repeat coronary angiography should be considered.Incidence and Mechanism of Coronary Obstruction After VIVIn the setting of native aortic valve stenosis, transcatheter aortic valve replacement (TAVR) is associated with a relatively low risk of coronary ostial obstruction, consistently <1%.8,9 Most commonly, the left main artery is involved, whereas obstruction of the right coronary is infrequent.10 Similarly, acute hemodynamic collapse is common although delayed presentation may also occur.7,11 Importantly, coronary obstruction is 3- to 4-fold more common after VIV TAVR when compared with native valve TAVR.8 The VIV International Data (VIVID) Registry initially reported a coronary obstruction incidence of 3.5% of patients and 2.5% in a recent multicenter registry for coronary obstruction.7,8 Arguably, this phenomenon may be underestimated because coronary obstruction can be incomplete or mitigated by patent bypass grafts.Assessing the risk of coronary obstruction requires understanding the mechanisms involved. Most commonly, coronary obstruction is the consequence of a bioprosthetic leaflet coming in direct, or near-direct, contact with a coronary ostium, or with the aortic root surrounding a coronary ostium (Figure 2A and 2B). This concern is universal to all transcatheter heart valve (THV) designs and is dependent on the characteristics of the surgical bioprosthesis and the relationship of its leaflets with the coronary ostia (Table 1).Table 1. Possible Risk Factors for Coronary Obstruction After Valve-in-Valve ImplantationAnatomic factors Low-lying coronary ostia Narrow sinotubular junction/low sinus height Narrow sinuses of Valsalva Previous root repair (eg, root graft and coronary reimplantation)Bioprosthetic valve factors Supra-annular position High leaflet profile Internal stent frame (eg, Mitroflow, Trifecta) No stent frame (homograft, stentless valves) Bulky leafletsTranscatheter valve factors Extended sealing cuff High implantationDownload figureDownload PowerPointFigure 2. A, A model of an aortic root with a surgical bioprosthesis (Mitroflow 27). B, Implantation of a 26-mm Sapien XT results in coronary ostium occlusion (arrow). C, Schematic drawing illustrating the implantation of a THV into a stented bioprosthesis with 3 posts in the setting of a coaxial aligned bioprosthesis in a capacious aortic root (right), a noncoaxial (tilted) bioprosthesis in a capacious aortic root (middle), and a coaxial aligned bioprosthesis in a noncapacious aortic root with a narrow sinotubular junction (left). Top, A left main view, the lower image a short-axis view at the level of the left main ostium. For assessment of the VTC distance, a virtual ring with the diameter of the fully expanded, anticipated THV is superimposed onto the short-axis image. Compared with the sinus diameter and the coronary ostia height, which are equal in left and middle examples, the VTC distance also accounts for the relative orientation of the bioprosthesis with in the aortic root.The distance between the annulus and the coronary ostia, commonly assessed in the setting of native valve TAVR, is less relevant when evaluating the risk for coronary obstruction associated with VIV implantation. The main predisposing factor in the setting of VIV is the proximity of the coronary ostia to the anticipated final position of the displaced bioprosthetic leaflets after THV implantation. After THV implantation, the surgical valve leaflets typically extend up in a somewhat tubular fashion from the circular frame to which they are attached. To some degree, the 3 commissural posts of a typical stented bioprosthesis may limit the outward displacement of the bioprosthetic leaflets. However, these valve posts are generally easily deflected outward by an oversized THV. Furthermore, cardiac surgeons typically place these posts aligned with the native valve commissures, remote from the coronary ostia, thus limiting its protective role in VIV implantation. In addition, the surgical prosthesis may have been implanted in a slightly tilted position in regard to the long axis of the aortic root, which may lead to the reduction of the distance of the prosthesis to a coronary ostium.Because coronary obstruction is usually the result of interaction between a surgical bioprosthesis and the coronary ostium, predisposing factors for coronary obstruction may include a supra-annular bioprosthetic valve, a narrow and low-lying sinotubular junction, bulky bioprosthetic leaflets, low-lying coronaries in narrow aortic root (shallow sinuses, previous root reconstruction), and reimplanted coronaries. It should be emphasized that coronary obstruction is not caused by low position of the coronary ostia unless the sinuses are relatively shallow. In addition, coronary obstruction may be more common with stenotic (often bulky), as opposed to regurgitant bioprostheses.6 Stentless bioprosthetic valves or those that are internally stented (eg, Mitroflow, Sorin; Trifecta, St. Jude Medical) may be at a higher risk because the leaflets of these bioprostheses may extend outward in a tubular fashion after VIV implantation beyond the surgical device frame (Figure 2A and 2B).12 Yet, it should be noted that Mitroflow is one of the most common bioprosthesis in the VIVD registry and in majority of setting these VIV cases the procedure was uneventful. Nevertheless, it could be suggested that prevention of coronary obstruction in VIV starts at the index surgical valve replacement. Device selection during surgery and technical approach inside the aortic root may have a significant clinical effect when these patients are considered for VIV years later.Fluoroscopic AssessmentAortic root angiography can be extremely helpful in identifying patients at risk for coronary occlusion (Table 2). Unfortunately, aortic root angiography is often not performed or performed suboptimally for the purposes of coronary ostial evaluation. Poor contrast enhancement of the aortic root, injections well above the sinotubular junction, while panning, at low magnification, or with an inadequate contrast volume are common technical issues. Figure 3 displays common technical errors that may limit the ability of angiography to assess coronary occlusion risks.Table 2. Optimal Fluoroscopic and Angiographic Assessment for Coronary Occlusion in Valve-in-ValveCollimated high frame rate imaging of a magnified areaContrast injection slightly above the surgical valveLarge amount of contrast (especially in regurgitant valves, in selective cases simultaneous double catheter injections)Perpendicularity to the bioprosthesisPerpendicularity to coronary ostium (if unknown an attempt in LAO-cranial projection for left main)Semiselective coronary injectionsAlignment of bioprosthesis posts (1-2 vs 1-1-1)Injection above an inflated aortic balloon (before device implantation)LAO indicates left anterior oblique.Download figureDownload PowerPointFigure 3. Common technical issues limiting fluoroscopic assessment of the risk for coronary obstruction after valve-in-valve. A, Catheter location is too high. B, Limited contrast volume in a regurgitant bioprosthesis. C, The view is not perpendicular to the surgical bioprosthesis. D, The view is not perpendicular to the left main ostium (picture in circle shows the aortic root in a view perpendicular to the left main).The optimal angiographic projection to assess coronary obstruction risk should be perpendicular to both the surgical bioprosthesis and the coronary ostia. Because left coronary obstruction is most common and of greater clinical effect, special attention to the relationship between the bioprosthesis and the left coronary ostium should be undertaken. The plane of the bioprosthetic valve is typically tilted up to the left, and the left coronary artery typically originates posteriorly from the aorta. Consequently, a left anterior oblique projection with cranial angulation is generally required. Determining the optimal plane perpendicular to the bioprosthesis can usually be accomplished by finding a fluoroscopic projection where the radiopaque components of the circular bioprosthetic basal ring appear as a straight line or the radiopaque components of the valve posts appear to be at the same height (Figure 4A, mosaic with post markers; Figure 4E, Edwards valve with both ring and posts visible; Figure 5A, Mitroflow with radiopaque ring). If the bioprosthesis is radiolucent, then a perpendicular view may be identified when angiography demonstrates 3 symmetrical cusps.Download figureDownload PowerPointFigure 4. Fluoroscopic evaluation of coronary obstruction risk in a mosaic (A–D) and a Perimount (E–H) bioprostheses. A, The small eyelets in the top of the posts are aligned in 1-1-1 fashion. Even though the projection is perpendicular to the bioprosthesis, coronary obstruction risk is difficult to define (Movie I in the Data Supplement). B, Semi-selective injection in the left main ostium after aligning 2 posts together (arrow) in 1-2 fashion (Movie II in the Data Supplement). C, Reconstruction of the bioprosthesis position in the root reveals that coronary flow will be maintained after valve-in-valve (arrow). D, Semiselective injection to the right coronary ostium after aligning 2 posts together (arrow) in 1-2 fashion show that the risk for coronary obstruction is low. E, Bioprosthesis posts are aligned in 1-1-1 fashion. Even though the projection is perpendicular to the bioprosthesis, coronary obstruction risk is difficult to define (Movie III in the Data Supplement). F, Semiselective injection in the left main ostium after aligning 2 posts together (arrow) in 1-2 fashion (Movie IV in the Data Supplement). G, Reconstruction of the bioprosthesis position in the root reveals that coronary flow will be maintained after valve-in-valve (arrow). H, Semiselective injection in the right coronary ostium after aligning 2 posts together (arrow) in 1-2 fashion show that the risk for coronary obstruction is low.Download figureDownload PowerPointFigure 5. Fluoroscopic evaluation of coronary obstruction risk in Mitroflow bioprostheses (A–F). A and B, Low risk for coronary obstruction. C and D, High risk for coronary obstruction. E and F, The posts of the Mitroflow are radiolucent. Having a projection perpendicular to both the bioprosthesis and left main allowed for visualization of leaflet motion (arrows) in diastole (E) and systole (F) showing extension of the leaflet above the coronary ostium revealing high risk for occlusion (Movie V in the Data Supplement).Finding a projection perpendicular to the coronary ostia is more complex. A simple maneuver that provides perpendicularity to the coronary ostia is the 1-2 technique (Figure 4). The fundamental principle is that surgeons typically implant aortic bioprostheses in a fashion that avoids positioning the commissural posts directly in front of the coronary ostia. The coronary ostium are typically mid distance between 2 posts (Figure 2A); consequently, a projection perpendicular to a coronary ostium is usually achieved when the 2 adjacent posts are perfectly superimposed (Figure 3). In a 1-2 view, the superimposed posts are located both anterior and posterior to the surgical valve leaflet that extends more laterally. However, the surgical valve leaflet will commonly not extend more lateral than the most lateral position of the ring (Figure 4C and 4G). The 1-2 maneuver maybe performed for either the left main or for the right coronary ostium. Usually 1 combination will allow for perpendicularity for the left main, whereas another combination will enable perpendicularity for the right coronary ostium. Obviously, this technique is of little value when the bioprosthetic valve posts are radiolucent (ie, Mitroflow). However, in this case, the radiopaque and saddle-shaped valve ring will often bear a constant relationship to the valve posts, facilitating easy identification of an equivalent view (Figure 5).Coronary AngiographyCoronary angiography can suggest high risk for occlusion and can also reveal the size of the territory at risk if occlusion occurs. Ostial coronary stenosis may probably add to a risk of complete occlusion in some cases. Patency of bypass grafts, significant collateral flow, and right versus left coronary dominancy may alter the clinical significance of coronary occlusion.Poor contrast opacification of the aortic root is relatively common in patients with failed bioprostheses. Aortic regurgitation leads to a rapid clearing of contrast from the aortic root and is common, being at least moderate in 61% of failed bioprosthesis in the VIV International Data registry.6 Semiselective injection of contrast in coronary ostia may provide optimal assessment of the geometric relationship between the failed surgical valve and the coronary ostia with little contrast (Figures 4 and 5). As outlined above, injection should be performed in a projection that will be both perpendicular to the surgical valve and to the coronary ostium. When faced with no or an inadequate aortic root angiogram, a review of the diagnostic selective coronary angiograms, particularly left anterior oblique cranial injection of the left coronary, will occasionally reveal adequate reflux to allow for assessment of the relationship between the bioprosthetic valve and the ostium of the left main.Computed Tomographic EvaluationMultidetector computed tomography (CT) is an important tool for assessing the risk of coronary occlusion in native valve TAVR.8,13 Although the optimal methodology for CT screening of the risk of coronary occlusion in the context of VIV is still in evolution, the integration of CT screening has already been shown to enable a reduction in the incidence of coronary occlusion in VIV.14CT allows for 3-dimensional assessment of the aortic root dimensions and assessment of the relative position of the components of the surgical prosthesis as they relate to anatomic landmarks. Analogously to CT assessment before native TAVR, relevant anatomic measurements include the height of the coronary ostia in relation to the sewing ring, the width and height of the sinus of Valsalva, and the width of the sinotubular junction (Table 3). However, these aforementioned measurements do not account for the relative position of the surgical prosthesis component toward the coronary ostia. For VIV, the positioning and angulation of the bioprosthesis can result in significantly higher risk for coronary occlusion than would be predicted by the positioning and configuration of the sewing ring. As a result, after identifying the sewing ring plane or the basal ring, it is essential to evaluate the geometric axis of the surgical prosthesis at the level of the coronary artery ostia, which is usually divergent from the long axis of the aortic root. Furthermore, the anticipated distance of the THV to the coronary ostia can be estimated (virtual THV-coronary distance). This is optimally performed by superimposing a virtual ring simulating the diameter of the anticipated, fully expanded THV centered along the geometric center of the surgical prosthesis followed by a caliper measurement from the ring toward the coronary ostium (Figure 6). This measurement provides a marker of the capacity of the root to accommodate the THV while maintaining flow to the coronary arteries and also accounts for the frequent eccentric position of the surgical prosthesis within the aortic root. Smaller virtual THV-coronary distances may confer, at least mechanistically, an increased hazard for coronary occlusion. For practical purposes, we stratify risk based on virtual THV-coronary distance: high risk: 6 mm. In addition, for stented valves, it is important to determine whether the stent posts extend above the coronary arteries. For stentless valves, a greater focus on the sinus geometry and short-axis dimensions is important because the sinuses are often effaced and this can result in an increased risk of coronary flow obstruction. Although the diameter of the aortic root at the level of the left coronary ostia seems to be an important measure in native TAVR, it does not account for the sometimes eccentric position of a slightly tilted surgical prosthesis.Table 3. Computed-Tomographic Assessment for Coronary Occlusion With Valve-in-ValveCoronary and bypass graft parameters Stenosis in coronary ostia Patency of bypass graftsAortic root parameters Sinus of Valsalva diameter Sinus heightBioprosthesis Leaflet thickness, significant pannus calcification, or bulkiness Post heightBioprosthesis–root relationship Sewing ring plane to coronary ostial height (if below coronary ostia less important) Distance from a virtual ring defined by the posts to the sinus of Valsalva Distance from a virtual ring defined by the posts to coronary ostia VTC distance: virtual THV to coronary ostia (ring at the level of the top of the posts and in a size of THV device to be implanted): high risk 6 mmTHV indicates transcatheter heart valve; and VTC, virtual THV-coronary distance.Download figureDownload PowerPointFigure 6. Contrast-enhanced ECG-gated computed tomography for the assessment of coronary occlusion risk. A–C, Failed Mitroflow 23 bioprosthesis at high risk for coronary occlusion. Sinuses are effaced and the coronary to ring distance is short. Short axis at the level of the top of the posts (arrows, B). A virtual 23-mm ring at the level of the coronaries revealing virtual THV-coronary (VTC) distance of only 1.98 mm (C; <3 mm considered high risk). D–F, Failed M
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