By Rebecca Hahn
Rebecca Hahn reviews the expanding role of echocardiography in transcatheter aortic valve implantation (TAVI), discussing the use of this imaging modality in treatment planning, intraprocedure guidance, and post-procedure assessment.
Transcatheter aortic valve implantation (TAVI) has become an accepted alternative to open heart surgery for the treatment of severe, symptomatic aortic stenosis in the high risk or inoperable patient1,2. Although numerous imaging modalities are essential to this procedure such as computed tomography and fluoroscopy, echocardiography is the primary imaging modality for pre-procedural patient selection, intra-procedural guidance, post-procedural assessment and long-term follow-up.
Echocardiography plays a critical role in the TAVI procedure. With the publication of recent reviews on the use of echocardiography in interventional procedures3, new guidelines on the use of three-dimensional (3D) echocardiography4 and transoesophageal echocardiography (TEE)5, and studies on the utility of this imaging tool specifically for TAVI6–8 , this role seems to be expanding. A comprehensive understanding of the TAVI procedure is essential for the successful integration of echocardiographic imaging into the interventional laboratory.
Although all cardiac structures should be assessed prior to the procedure as per recent American Society of Echocardiography TEE guidelines5, the TAVI-specific imaging typically begins with an assessment of the transcatheter heart valve landing zone. This includes the left ventricular outflow tract, the aortic annulus, aortic cusps and sinuses of Valsalva, coronary ostia and sinotubular junction. Treatment plans may be significantly altered by consideration of the risks outlined in Table 1. The use of 3D TEE has significantly improved the accuracy of this assessment, particularly the measurement of the aortic annular area and perimeter9–15 as well as the coronary ostial height3,16.
Once the pre-implant assessment is complete, intra-procedural imaging of wire placement (pacing wire and left ventricular stiff wire) and balloon aortic valvuloplasty is also performed. Incorrect stiff wire placement can create haemodynamically-significant mitral regurgitation or prevent stabilisation of the heart valve. Imaging of the balloon aortic valvuloplasty procedure can rapidly detect uncommon complications such as severe aortic regurgitation, but can also be used diagnostically to size the annulus or predict coronary occlusion. Valve positioning using the assistance of TEE imaging may reduce contrast load or fluoroscopic time. Checking valve position during the pacing run may be particularly useful in avoiding malpositioning of the valve. Finally, post-implant assessment of valve size, shape and function can be performed rapidly using simultaneous multiplane imaging, a function of the 3D imaging systems. The causes of haemodynamic collapse such as annular or ventricular rupture and severe aortic regurgitation can be diagnosed within seconds, allowing swift and likely lifesaving intervention. The need to treat paravalvular regurgitation with post-dilatation or valve-in-valve implantation can be rapidly determined by TEE.
In summary, echocardiography is an integral part of every aspect of the TAVI procedure. TEE can be used pre-procedurally for 3D annular sizing as well as the assessment of risk for complications. Intra-procedural TEE can assist in wire placement and heart valve position. Finally, the rapid assessment of cardiac and valvular function following implantation may improve response time in critical but treatable haemodynamic emergencies.
Rebecca Hahn is director of Interventional Echocardiography, and associate professor of Medicine at Columbia University Medical Center/New York-Presbyterian Hospital, New York, USA
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2. Smith et al. N Engl J Med 2011; 364: 2187–98
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4. Lang et al. J Am Soc Echocardiogr 2012; 25: 3-46
5. Hahn et al. J Am Soc Echocardiogr 2013; 26: 921–66
6. Smith et al. J Am Soc Echocardiogr 2013; 26: 359–69
7. Hahn et al. J Am Soc Echocardiogr 2013; 26
8. Janosi et al. Minim Invasive Ther Allied Technol 2009; 18: 142–48
9. Santos et al. Eur Heart J Cardiovasc Imaging 2012; 13: 931–37
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12. Gripari et al. Heart 2012; 98: 1229–36
13. Jilaihawi et al. J Am Coll Cardiol 2013; 61: 908–16
14. Husser et al. Catheter Cardiovasc Interv 2012.
15. Shahgaldi et al. Cardiovasc Ultrasound 2013; 11: 5
16. Tamborini et al. JACC Cardiovasc Imaging 2012; 5: 579–88
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