A 94-year-old man with a history of severe symptomatic aortic stenosis, atrial fibrillation, hypertension, and left main coronary artery disease presented for transcatheter aortic valve implantation (TAVI) via the transfemoral approach; written consent was obtained from the patient for presentation of this case. Given his age and comorbidities, a left main coronary stent was placed for his proximal left main coronary disease before TAVI. Technical considerations resulted in the stent protruding into the aortic root at the level of the sinotubular junction.
Intraoperative transesophageal echocardiography (TEE) was performed using a Philips iE33 ultrasound system with an X7-2t TEE probe (Philips Healthcare, Andover, MA) revealing severe aortic valve (AV) stenosis (valve area 0.6 cm2 by the continuity equation; mean gradient 44 mm Hg; peak gradient 78 mm Hg) with significant calcific degeneration and minimal motion of all 3 coronary cusps; mild aortic regurgitation was noted. The AV annular and sinotubular junction diameters were 23 mm and 25 mm, respectively. Mild-to-moderate tricuspid regurgitation, no mitral valve regurgitation, no significant left ventricular wall motion abnormalities, and left ventricular ejection fraction estimated as 66% were also noted. An echodense structure was visible in the aortic root at the level of the sinotubular junction in the midesophageal (ME) long-axis (LAX) view (Fig. 1 and Video 1, Loop 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A478) and ME short-axis (SAX) view near the left coronary cusp (Video 1, Loop 2, Supplemental Digital Content 1, http://links.lww.com/AA/A478); it was also visible with fluoroscopy and consistent with a left coronary ostial stent protruding approximately 0.5 cm into the aortic root. Two-dimensional color-flow Doppler interrogation demonstrated flow through the stent, and real-time 3-dimensional TEE imaging provided additional confirmation of stent protrusion (Fig. 2A).
Because the implanted bioprosthetic AV is deployed within the native AV extending below and above the annulus and into the sinuses of Valsalva, the optimal postdeployment position places the implanted valve close to the site of the left main coronary stent; therefore, to guide optimal TAVI deployment, additional TEE interrogation was performed. In the ME AV LAX view (Video 2, Loop 1, see Supplemental Digital Content 2, http://links.lww.com/AA/A479), the optimal location for the implanted valve and the marginal distance to the left main ostial coronary stent were defined using caliper line measurements (Video 2, Loop 2, Supplemental Digital Content 2, http://links.lww.com/AA/A479); these measurements were based on use of a 26 mm diameter (16 mm length) Edwards-Sapien (Edwards Lifesciences, Irvine, CA) bioprosthetic valve. However, the implanted valve can be incorrectly deployed or migrate too far into the left ventricular outflow tract or the aortic root (Video 2, Loop 3, Supplemental Digital Content 2, http://links.lww.com/AA/A479). Because malpositioning or migration of the bioprosthetic valve might occlude the ostial coronary stent, a wire guide (0.014 × 190 HTB, Abbott Laboratories, Abbott Park, IL) was inserted into the left main coronary artery to protect access to the left main artery stent (Fig. 2B). After deployment of the bioprosthetic AV, 2-dimensional TEE interrogation revealed good positioning of the valve (Fig. 3) without disruption of anterior mitral leaflet motion or occlusion of the left main ostial coronary stent in both the ME LAX and ME SAX views (Video 3, Loops 1 and 3, see Supplemental Digital Content 3, http://links.lww.com/AA/A480); a mild posterior paravalvular regurgitatant jet was noted.
TAVI involves either a transfemoral or transapical approach to replace a stenotic AV with an expandable bioprosthetic AV (also known as stent valves or valved stents) positioned within the preexisting AV using a balloon dilator expander during rapid ventricular pacing. This technique has been demonstrated to be a viable alternative for patients requiring conventional AV replacement who are poor surgical candidates.1 We describe a unique clinical situation in which TEE was used to facilitate optimal positioning to avoid obstruction of an in situ left main ostial coronary artery stent and to assess the stent’s protection with a guidewire placed in its lumen.
While concomitant fluoroscopic guidance is used during various phases of TAVI, TEE serves a complementary and unique role during TAVI.2,3 During the preoperative evaluation, TEE can be used to confirm AV stenosis, delineate the shape and size of the left ventricular outflow tract, locate coronary ostia, define AV annular dimensions for prosthetic valve sizing purposes, and establish the presence of coexistent valvular pathology. Currently, only 2 sizes (23 mm diameter/14 mm length and 26 mm diameter/16 mm length) of transcatheter implantable AVs are available in the Unites States; however, smaller and larger valves (i.e., 19 mm diameter and 29 mm diameter) are pending release. After deployment of the prosthetic valve, TEE is used to assess motion of the prosthetic valve leaflets, detect paravalvular regurgitation, define the location of the prosthetic AV, monitor left ventricular function, and assess possible occlusion of the coronary ostia or, in this case, to determine the potential effect on a protruding coronary stent while also assessing protection of an ostial coronary stent. TEE can also evaluate possible bioprosthetic AV embolization, aortic root perforation/dissection, or mitral valve disruption.
Percutaneous coronary intervention for left main coronary disease is typically only considered in the absence of other revascularization options,4,5 and ostial coronary stents may protrude into the lumen of the sinus of Valsalva or aortic root by several millimeters.6 After TAVI, occlusion of the left or right coronary ostia may occur secondary to obstruction by either the native valve leaflets or the bioprosthetic valve itself;7,8 therefore, a protruding in situ coronary stent may possibly reduce the marginal distance between the implanted valve and the coronary ostia.
Two-dimensional and real-time 3-dimensional TEE interrogation may be useful in defining the anatomic location of the coronary ostia and/or in situ ostial coronary stent(s) and their possible protrusion into the respective sinus of Valsalva. In this case, the left main coronary ostial stent was best imaged in the LAX configuration as a circular echogenic density. In the ME AV LAX view, caliper line measurements were performed before valve implantation to approximate the length of the bioprosthetic valve as well as the distance between the implanted valve and the coronary stent (Video 2, Loop 2, see Supplemental Digital Content 2, http://links.lww.com/AA/A479). Wire guide protection of an ostial coronary stent was used to maintain access to the ostial stent in the event of occlusion (Fig. 2B). Because larger bioprosthetic AVs have a longer length compared with smaller bioprosthetic valves, they might have a greater risk of stent occlusion. However, experience with this specific scenario is limited. In addition, future larger valves may pose additional risk of coronary ostial occlusion; however, this remains to be determined, and no cases have been reported.
In summary, we present a case of TAVI in close proximity to a protruding left main ostial coronary artery stent demonstrating the usefulness of TEE for optimization of ostial stent protection.
Name: Antonio Hernandez Conte, MD, MBA.
Contribution: This author helped conduct the study, analyze the data, conduct the anesthetic management, perform transesophageal echocardiography, manuscript preparation and write the manuscript.
Name: Swaminatha V. Gurudevan, MD, FACC, FASE.
Contribution: This author helped conduct the echocardiographic study, perform transesophageal echocardiography and write the manuscript.
Name: Lorraine Lubin, MD.
Contribution: This author helped analyze the data, prepare images and write the manuscript.
Name: Takahiro Shiota, MD, PhD, FASE.
Contribution: This author helped evaluate the study and prepare images.
Name: Troy LaBounty, MD, FACC.
Contribution: This author helped analyze the data, prepare images and write the manuscript.
This manuscript was handled by: Martin J. London, MD.
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Clinician’s Key Teaching Points
By Martin M. Stechert, MD, Nikolaos J. Skubas, MD, and Martin J. London, MD
- In transcatheter aortic valve implantation (TAVI) an expandable bioprosthetic aortic valve is inserted transcutaneously and positioned within a preexisting stenosed aortic valve. Periprocedural transesophageal echocardiography (TEE) imaging is important for establishing the diagnosis of aortic stenosis and describing the anatomy of the aortic root, verifing the proper position and function of the prosthetic valve and monitoring for complications.
- The scaffold (stent) of a properly positioned expandable bioprosthetic aortic valve extends below as well as above the aortic annulus, so that the proximal and distal ends lay in close proximity to the anterior mitral leaflet and coronary ostia, respectively. Malposition may result in disruption of the mitral leaflet motion and/or obstruction of coronary blood flow and myocardial ischemia.
- In this case of a patient undergoing a TAVI procedure, an echodense structure was imaged in the midesophageal aortic valve short-axis and long-axis views, near the left coronary cusp, consistent with a coronary stent that was previously inserted into the left main coronary artery. TEE with color-flow Doppler was used to demonstrate normal flow through the coronary stent and real-time 3-dimensional TEE confirmed the protrusion inside the sinuses of Valsalva. A wire guide was inserted into the coronary stent, to ensure that, after the TAVI procedure, it would not be obstructed by the distal end of the expandable aortic valve.
- TEE and fluoroscopy are complementary imaging techniques during a TAVI procedure. TEE is invaluable to monitor the function of the bioprosthetic aortic valve leaflets and diagnose intraprosthetic and paraprosthetic regurgitation as well as prevent or diagnose potential complications because of malposition.