Percutaneous Interventions for Valvular Heart Disease
Hong Jun (Francisco) Yun, MD
Stanley J. Chetcuti, MD
TRANSCATHETER AORTIC VALVE INTERVENTIONS
Aortic stenosis is the most common valvular heart disease in developed countries, with increasing prevalence as the population ages. Left untreated, severe, symptomatic aortic stenosis has a poor prognosis with mortality rates approaching 50% at 2 years.1 Traditionally, surgical aortic valve replacement (SAVR) represented the only treatment available to relieve the left ventricular outflow obstruction, alleviate symptoms, and improve survival.2 Despite the class I indication from the American College of Cardiology/American Heart Association (ACC/AHA) guidelines for aortic valve replacement in patients with severe, symptomatic aortic stenosis, nearly one-third of patients are not referred for or declined treatment, often due to multiple comorbidities as well as anatomic factors that make patients poor candidates for SAVR.3 The emergence of transcatheter aortic valve replacement (TAVR) over the past decade has provided a feasible and lower-risk option for the frail and elderly who are deemed poor candidates for surgery.
Currently, 2 TAVR platforms have been approved by the U.S. Food and Drug Administration: the CoreValve Revalving System (Medtronic, Minneapolis, MN) and the Edwards Sapien System (Edwards Lifesciences, Irvine, CA). The landmark Placement of AoRTic TraNscathetER Valve Trial (PARTNER) demonstrated the superiority of TAVR using the balloon-expandable Edwards Sapien valve compared with medical therapy in extreme surgical risk patients (all-cause mortality, 71.8% vs 93.6% for TAVR vs medical therapy [Hazard Ratio 0.50, 95% CI 0.39-0.65, P < .0001]), as well as noninferiority of TAVR to SAVR in high-risk patients (all-cause mortality, 67.8% vs 62.4% for TAVR vs SAVR [HR 1.04, 95% CI 0.86-1.24; P = .76]) at 5 years.4,5 Subsequently the US Pivotal CoreValve trials using the self-expanding valve prosthesis not only showed favorability for TAVR in the extreme surgical risk patients but also demonstrated superiority of TAVR to SAVR in the high-risk patient population (all-cause mortality, 14.2% vs 19.1% absolute risk reduction 4.9%, P = .04 for superiority).6,7 Given the promising results of these landmark trials using the first generation platforms, further studies have been carried out to define the role of TAVR in lower-risk patients. The PARTNER-2 trial showed noninferiority of the Edwards Sapien XT valve in intermediate surgical risk patients with severe aortic stenosis randomized to SAVR versus TAVR (primary endpoint of all-cause death or stroke, 19.3% vs 21.1% [HR 0.89, 95% CI 0.73-1.09, P = .25]).8 TAVR also compared favorably with surgery in terms of lower rates of bleeding, kidney injury, and new-onset atrial fibrillation. Although TAVR was associated with higher rates of paravalvular regurgitation (PVR), the Sapien XT valves resulted in better hemodynamics with lower gradients and larger valve areas compared with surgical valves. Similarly, the Safety and Efficacy Study of the Medtronic CoreValve® System in the Treatment of Severe, Symptomatic Aortic Stenosis in Intermediate Risk Subjects Who Need Aortic Valve Replacement (SURTAVI) trial, an intermediate risk study using the second generation Medtronic CoreValve, demonstrated noninferiority of TAVR versus SAVR with respect to the primary endpoint of all-cause death or disabling stroke (12.6% vs 14.0%; 95% credible interval [Bayesian analysis] for difference, -5.2%-2.3%; posterior probability of noninferiority, >0.999).9
Based on the results of these trials, advances to newer generation devices, and refinements in the procedural approach, TAVR provides an effective, minimally invasive therapeutic option for patients with severe aortic stenosis, who previously were left untreated. This paradigm shift has been reflected in the most recent 2017 valvular heart disease guidelines endorsed by the ACC/AHA that recommend either surgical AVR or TAVR for high-risk patients (class I) and make TAVR a reasonable alternative to SAVR in intermediate-risk patients (class IIa) after assessment by a heart valve team.10
TRANSCATHETER AORTIC VALVE REPLACEMENT: EDWARDS SAPIEN VALVE
Edwards Sapien Valve and Commander Delivery System (Figure 21.1)
 FIGURE 21.1 A, The Edwards Sapien valve is a trileaflet bovine pericardial valve mounted on a balloon-expandable, radio-opaque cobalt chromium stent. The low frame height and open cell geometry promote access to the coronary arteries for future interventions. The newest genera tion Edwards Sapien 3 valve includes a polyethylene terephthalate outer skirt to reduce PVR, and it is available in 4 sizes (20, 23, 26, and 29 mm). B, The Commander delivery system incorporates a nose-cone-tipped inner balloon catheter on which the prosthesis is crimped and an outer deflectable flex catheter. An attached handle incorporates a rotating wheel used to deflect the flex catheter tip, a fine adjustment wheel for fine alignment of the prosthesis during valve alignment, a balloon lock knob to secure the balloon catheter to the flex catheter, and a flush port. The balloon catheter contains radio-opaque valve alignment markers, defining the valve alignment position and working length of the balloon. A central radio-opaque marker in the balloon assists in valve positioning. The delivery system allows for advancing or retracting the valve several millimeters up or down within the annulus by rotating the fine alignment wheel. |
Preprocedural Planning Using MDCT (Figure 21.2)
 FIGURE 21.2 Key measurements to determine appropriate sizing of the TAVR are shown at the levels of the (A) annulus (perimeter: 64 mm, area: 3.2 cm2), (B) left ventricular outflow tract (LVOT), (C) sinus of Valsalva,(D) sinotubular junction (STJ). |
Successful Deployment
Preprocedural planning using MDCT is integral to successful device deployment (FIGURE 21.3.)
 FIGURE 21.3 A and B, Multidetector computed tomography (MDCT) reconstruction of the optimal fluoroscopic implant view or “coplanar” view, where all 3 cusps are seen in a line, and the aortic root orientation. B, The aortoventricular angle is best determined from the coronal view by determining the angle of the horizontal plane at the level of the ventricle and aortic annulus angulation. C and D, MDCT demonstrating the burden of calcification of the native aortic valve leaflets, annulus, and LVOT. Excessive leaflet calcification is a potential risk for coronary obstruction while increased LVOT or annular calcification is a risk factor for PVR (especially asymmetric calcification) and annular rupture.11 The burden of calcium at the aortic annulus has been directly correlated to rates of complete heart block, degree of PVR, risk of annular rupture, and, in certain circumstances, residual post-implant gradients.12,13,14 |
Peripheral Vascular Access
Imaging of the peripheral vascular system using MDCT is crucial to access vessels for implantation and minimize the risk of vascular complications. Multiple measurements are taken along the common iliac, external iliac, common femoral, innominate, subclavian, and proximal axillary arteries bilaterally. FIGURE 21.4 displays a 3D computed tomography (CT) reconstruction of the peripheral vasculature with sequential axial cuts, illustrating lumen size, tortuosity, and calcification. The vessel anatomy is suitable for a 23 mm Edwards Sapien 3 valve through a 14 FR delivery system.
 FIGURE 21.4 MDCT of peripheral vasculature access vessels. |
CASE 1 Patient With Severe Aortic Stenosis
 FIGURE 21.5 Transfemoral transcatheter aortic valve replacement in a patient with severe aortic stenosis using 23 mm Edwards Sapien 3 valve. |
As shown in FIGURE 21.5A, a pigtail catheter placed in the noncoronary cusp, an aortogram is performed in the optimal deployment projection or coplanar (
Video 21.1). In FIGURE 21.5B, the aortic valve prosthesis and delivery system are advanced over a preshaped Safari guide wire (Boston Scientific, Marlborough, MA, USA). The retroflex catheter is activated to allow the passage of the valve through the aortic arch. Correct positioning is confirmed with fluoroscopy and transesophageal echocardiography (TEE) (
Video 21.2). The valve is deployed during rapid ventricular pacing at 180 beats per minute (bpm) (FIGURE 21.5C, 
Video 21.3). A final aortogram is performed and confirms optimal valve position, mild aortic insufficiency, and unrestricted coronary flow (FIGURE 21.5D, 
Video 21.4). E, Iliofemoral angiography shows no vascular complications, and percutaneous closure is performed using Perclose ProGlide sutures (Abbott Vascular, Santa Clara, California, USA).
Video 21.1). In FIGURE 21.5B, the aortic valve prosthesis and delivery system are advanced over a preshaped Safari guide wire (Boston Scientific, Marlborough, MA, USA). The retroflex catheter is activated to allow the passage of the valve through the aortic arch. Correct positioning is confirmed with fluoroscopy and transesophageal echocardiography (TEE) ( Video 21.2). The valve is deployed during rapid ventricular pacing at 180 beats per minute (bpm) (FIGURE 21.5C, Video 21.3). A final aortogram is performed and confirms optimal valve position, mild aortic insufficiency, and unrestricted coronary flow (FIGURE 21.5D, Video 21.4). E, Iliofemoral angiography shows no vascular complications, and percutaneous closure is performed using Perclose ProGlide sutures (Abbott Vascular, Santa Clara, California, USA).Hemodynamic Tracings
 FIGURE 21.6 Hemodynamic tracings before and after successful transcatheter aortic valve replacement with an Edwards Sapien 3 valve in a patient severe aortic stenosis. |
In FIGURE 21.6, simultaneous aortic and left ventricular pressures are measured before (left panel) and after (right panel) device implantation. Before TAVR, a large LV-AO gradient, slow aortic pressure upstroke, and absence of a dicrotic notch are evident. After successful device deployment, the hemodynamic tracing reveals a minimal pressure gradient across the valve, recovery of brisk aortic upstroke, and a crisp dicrotic notch. The mean gradient across the aortic valve has decreased from 41 to 2 mm Hg.
Assessment of Transcatheter Heart Valves (THV)
 FIGURE 21.7 Echocardiography in the assessment of THV. |
Post-TAVR echocardiographic assessment guidelines were reviewed in a joint statement of the American and European Societies of Echocardiography and further endorsed by the Valve Academic Research Consortium (VARC).15,16 Follow-up echocardiography should be performed predischarge (or within 30 days after transapical TAVR), at 6 and 12 months, and then yearly. A systematic approach to imaging at follow-up includes visual inspection, hemodynamic assessment of the transcatheter heart valves (THV), assessment of adjacent cardiac structures, and assessment of ventricular function. This approach allows accurate diagnosis of common THV-related complications17. In FIGURES 21.7AB, 2D TEE images of an Edwards Sapien 3 valve immediately after deployment in short- and long-axis views illustrating the circular appearance of the new valve prosthesis deployed below the native aortic valve annulus. There is no evidence of paravalvular aortic regurgitation on color Doppler (FIGURE 21.7C).
TRANSCATHETER AORTIC VALVE REPLACEMENT: MEDTRONIC COREVALVE EVOLUT
 FIGURE 21.8 The Medtronic Evolut CoreValve and EnVeo Delivery Catheter System. |
The Medtronic CoreValve Evolut System is made of a trileaflet, supra-annular porcine tissue valve on a self-expanding nitinol frame (FIGURE 21.8). The nitinol frame conforms and seals to the noncircular annulus while preserving circularity at the height of the functioning valve. The nitinol frame geometry provides consistent radial force across the treated annulus. The newest generation Evolut Pro bioprosthesis has an added external porcine pericardial wrap to increase surface area contact and minimize paravalvular leak. The open frame geometry can accommo-date a 10 FR catheter for future coronary access. The Evolut valve is mounted on 14 and 16 FR EnVeo Delivery Catheter System (DCS) with an integrated inline sheath that allows for access without a separate introducer sheath. The EnVeo DCS provides uniform and controlled valve expansion in the annulus and the option to recapture and reposition up to 3 times. The device is able to treat annuli up to 30 mm and is available in 4 sizes (23, 26, and 29 mm Evolut Pro and 34 mm Evolut R).
Measurements and Assessments
Aortic Valve, sinuses of valsalva and coronary arteries
 FIGURE 21.9 MDCT measurements and assessment of the aortic valve complex. |
Accurate aortic annular measurements are key to determining the size of device and also in reducing the impact of paravalvular regurgitation (FIGURE 21.9). Adequate sinus of Valsalva width and height is required to avoid coronary occlusion. Other anatomic considerations include burden of calcification in the aortic valve apparatus, adequate aortoventricular angle less than 70° for iliofemoral and left subclavian access routes, and less than 30° for the right subclavian approach. MDCT reconstruction of the optimal fluoroscopic implant view or “coplanar” view is shown here. Key measurements to determine appropriate sizing of the TAVR are shown at the levels of the aortic valve annulus (min: 20.5 mm, max: 25.9 mm, perimeter: 73.7 mm), LVOT, sinus of Valsalva, and STJ. The perimeter is the preferred sizing measurement for the CoreValve Evolut platform. A 29 mm CoreValve Evolut Pro THV was chosen based on the above characteristics.
Peripheral Vascular Assessment
 FIGURE 21.10 Peripheral vascular assessment using MDCT. |
Important procedural considerations for vascular access include vessel size, degree and location of calcification, and tortuosity of the target vessels. CT with 3D reconstruction of the peripheral vasculature and sequential axial cuts, illustrating lumen size, tortuosity, and calcification of vessels, is shown here. Careful evaluation will determine the preferred side for access to deliver the THV in addition to the optimal location for common femoral artery puncture (ie, at sites absent of calcification) to allow for preclosure using Perclose ProGlide percutaneous sutures (FIGURE 21.10).
CASE 2 Patient with Severe Aortic Atenosis
 FIGURE 21.11 Transfemoral transcatheter aortic valve replacement in an 80-year-old patient with severe aortic stenosis and moderate risk for an open procedure using a 29 mm CoreValve Evolut Pro. |
A pigtail catheter is placed at the bottom of the noncoronary cusp, and a diagnostic aortogram is performed in the coplanar view (FIGURE 21.11A, 
Video 21.5). A 29 mm CoreValve Evolut Pro prosthesis and delivery system are advanced over a preshaped Safari guide wire to the level of implantation under fluoroscopy. The projection is adjusted to view the radiopaque marker band as a straight line before deployment (FIGURE 21.11B, 
Video 21.6). Using the linear markings on the valve, the valve is positioned 3 to 5 mm below the patient’s native valve and slowly released with pacing at 110 bpm using a Tempo (Biotrace, Menlo Park, CA) active fixation temporary pacemaker to maintain stability during valve deployment (FIGURE 21.11C, 
Video 21.7). At the 80% position and before the point of no recapture, an aortogram is performed revealing that the bioprosthesis has migrated above the native valve annulus and the decision is made to recapture the valve (FIGURE 21.11D, 
Video 21.8). A second deployment is initiated with the bioprosthesis again positioned 3 to 5 mm below native annulus (FIGURE 21.11E, 
Video 21.9). An aortogram is performed at the point of no recapture and shows the bioprosthesis at the optimal implant depth (FIGURE 21.11F, 
Video 21.10). The position of the valve is further confirmed by TEE before release. The remaining portion of the valve is fully deployed and confirmation of complete release of the valve from the loading system is confirmed on fluoroscopy (FIGURE 21.11G, 
Video 21.11). A final aortogram verifies that the CoreValve is deployed at the 5 mm mark with minimal aortic regurgitation (FIGURE 21.11H, 
Video 21.12).
Video 21.5). A 29 mm CoreValve Evolut Pro prosthesis and delivery system are advanced over a preshaped Safari guide wire to the level of implantation under fluoroscopy. The projection is adjusted to view the radiopaque marker band as a straight line before deployment (FIGURE 21.11B, Video 21.6). Using the linear markings on the valve, the valve is positioned 3 to 5 mm below the patient’s native valve and slowly released with pacing at 110 bpm using a Tempo (Biotrace, Menlo Park, CA) active fixation temporary pacemaker to maintain stability during valve deployment (FIGURE 21.11C, Video 21.7). At the 80% position and before the point of no recapture, an aortogram is performed revealing that the bioprosthesis has migrated above the native valve annulus and the decision is made to recapture the valve (FIGURE 21.11D, Video 21.8). A second deployment is initiated with the bioprosthesis again positioned 3 to 5 mm below native annulus (FIGURE 21.11E, Video 21.9). An aortogram is performed at the point of no recapture and shows the bioprosthesis at the optimal implant depth (FIGURE 21.11F, Video 21.10). The position of the valve is further confirmed by TEE before release. The remaining portion of the valve is fully deployed and confirmation of complete release of the valve from the loading system is confirmed on fluoroscopy (FIGURE 21.11G, Video 21.11). A final aortogram verifies that the CoreValve is deployed at the 5 mm mark with minimal aortic regurgitation (FIGURE 21.11H, Video 21.12).
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