Transcatheter Aortic Valve Replacement Technique

Updated: Dec 07, 2015
  • Author: Ramin Assadi, MD; Chief Editor: Eric H Yang, MD  more...
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Technique

Approach Considerations

The Edwards SAPIEN valve may be implanted via a TF or TA approach, and the Medtronic CoreValve system can be delivered through a femoral, subclavian, or direct aortic approach (direct aortic access can be achieved through either a ministernotomy or a minithoracotomy). [9, 26]

Vascular complications have been associated with significant mortality and may be prevented by accurate screening. Table 2 summarizes the minimal vessel diameter required for different transcatheter aortic valve systems.

Table 2. Minimum Required Arterial Access Diameter for Transcatheter Aortic Valve Replacement (TAVR) (Open Table in a new window)

Valve Size Sheath Size Minimal Arterial Diameter, mm
CoreValve
23 mm 18F 6
26 mm 18F 6
29 mm 18F 6
31 mm 18F 6
Edwards SAPIEN
23 mm 22F 7
26 mm 24F 8
Edwards-SAPEIN XT
23 mm 18F 6
26 mm 19F 6.5
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Transcatheter Aortic Valve Replacement - CoreValve

Venous access

Central venous access (preferably jugular or subclavian) is obtained, and a 5F balloon-tip pacing wire is positioned in a stable location within the right ventricle under fluoroscopy. After the pacing system is tested, the backup pacing rate is set at 50 beats per minute.

Arterial access

First, arterial access is obtained on the contralateral side to the planned 18F sheath for the CoreValve system. Then, arterial access for the 18F sheath is obtained. Arterial puncture can be performed percutaneously under angiographic or ultrasound guidance to ensure cannulation of the anterior common femoral artery, as this is essential for successful percutaneous closure. Alternatively, surgical cutdown can be used for access per performing center protocol and patient’s vascular anatomy.

Once access has been obtained, anticoagulation is administered to maintain an activated clotting time (ACT) of 250 seconds or more.

Crossing the native aortic valve

A 5F-6F graduated pigtail catheter is advanced to the ascending aorta, and the distal tip of the catheter is positioned in the noncoronary cusp of the native aortic valve.

The optimal annular viewing plane using contrast injections under fluoroscopy is then identified to allow visualization of all 3 coronary sinuses in the same plane, preferably in the left anterior oblique projection.

An Amplatz left (AL) diagnostic catheter is then advanced to the ascending aorta over a standard J-tip guidewire through the primary access sheath. The J-tip guidewire is then exchanged for a 0.035-inch straight-tip guidewire, which is used to cross the native valve. After crossing the aortic valve, the AL catheter is advanced into the left ventricle.

The straight-tip guidewire is exchanged for an exchange-length J-tip guidewire, and the AL catheter is exchanged for a 6F pigtail catheter. The guidewire is removed, and, after appropriate flushing, the pigtail catheter is connected to the pressure transducer. Using both pigtail catheters, the simultaneous pressures across the native aortic valve are recorded, and the pressure gradient is measured.

The distal portion of a 0.035-inch super-stiff guidewire is carefully pigtail-shaped to prevent inadvertent left ventricular perforation, and, in right anterior oblique projection, it is advanced through the pigtail catheter in the apex of the left ventricle. Maintaining the super-stiff guidewire position, the pigtail catheter is removed.

Balloon aortic valvuloplasty

Predilation of the aortic valve is then performed using an appropriately sized balloon. Balloon sizing should be directed to 1:1 (or less) sizing of the minimal annular diameter via CT angiography or echocardiography, with a maximum balloon size of 25 mm.

The valvuloplasty balloon is inserted through the 18F introducer sheath and advanced to the ascending aorta. Rapid pacing testing is then performed. A successful result is defined as 1-to-1 pacing capture with an immediate drop in pressure, reduction of the systolic-diastolic waveform, and reduction of the peak systolic pressure to less than 60 mm Hg. This is usually achieved by pacing at 180-200 beats per minute.

It is important to have the CoreValve prepared and mounted on the delivery system and ready to implant prior to BAV should acute severe aortic regurgitation and hemodynamic compromise result from valvuloplasty.

At this point, the valvuloplasty balloon is positioned across the aortic valve, while strict fluoroscopic surveillance of the distal tip of the super-stiff guidewire in the left ventricle is maintained.

After BAV is performed, the balloon is removed while maintaining the guidewire position. Aortography is then performed to assess the degree of aortic regurgitation. [9, 22, 26, 27]

CoreValve implantation

After valvuloplasty, the CoreValve device is advanced over the high-support 0.035-inch guidewire under careful fluoroscopic surveillance of the guidewire tip in the left ventricle. It is important to prevent the guidewire from moving forward as the device is advanced across the aortic arch.

The CoreValve bioprosthesis is then positioned across the aortic valve within the aortic annulus (< 6 mm below the annulus).

The annulus is defined as the angiographic floor of the native valve cusps.

After optimal positioning of the CoreValve delivering system is confirmed with fluoroscopy, the deployment is started by slow and clockwise turning of the microknob. As the inflow aspect of the bioprosthesis begins to flare outward, aortography is performed sequentially. Once annular contact is made, the device should not be advanced into a lower position.

Valve deployment is continued rapidly to the two-thirds deployment point; then, optimal placement of the bioprosthesis is confirmed with angiography. Valve position and function are also evaluated using hemodynamics and echocardiography.

When the optimal position is achieved, the microknob is continually turned until both frame loops disengage. Orthogonal views under fluoroscopy are used to confirm the frame loops have detached from the delivery catheter tabs.

The CoreValve delivery system is withdrawn carefully into the ascending aorta, avoiding contact with the inflow portion of the frame.

Table 3. Summary of Approved Sizes for CoreValve (Open Table in a new window)

Valve Size, mm Aortic Annulus Diameter, mm Ascending Aorta Diameter*, mm Sinus of Valsalva Diameter, mm Native Leaflet to Sinotubular Junction Length, mm
23 18-20 ≤34 ≥25 ≥15
26 20-23 ≤40 ≥27 ≥15
29 23-27 ≤43 ≥29 ≥15
31 26-29 ≤43 ≥29 ≥15
*Ascending aorta measurements are taken at 30 mm from the aortic annulus for the 23-mm device and at 40 mm from the aortic annulus for the 26-, 29-, and 31-mm devices.

During implantation, if resistance to deployment is encountered (eg, clicking of the microknob) or if the microknob is tight or stuck, apply mild upward pressure to the macro slider while turning the microknob. It the device still does not deploy, the bioprosthesis should be removed and another system used.

During the final deployment step, if one of the frame loops is still attached to the catheter tab, the catheter is slightly advanced under fluoroscopy; if necessary, the handle is gently rotated clockwise and counterclockwise (< 180° in each direction) to disengage the loop from the catheter tab.

Postdeployment

Once the CoreValve is deployed, the delivery system is withdrawn to the descending aorta while maintaining the guidewire position in the left ventricle, and the delivery system is removed through the 18F introducer sheath.

A 6F pigtail catheter is advanced into the left ventricle over the guidewire, and the guidewire is removed. Using the 2 pigtail catheters and 2 transducers, simultaneous left ventricular and aortic pressures are recorded, and the mean pressure gradient across the aortic valve is documented.

Postimplant aortography is performed to assess the degree of residual stenosis within the frame, the degree of aortic regurgitation, and patency of the coronary arteries (see videos below).

Echocardiographic 2-dimensional image of the CoreValve in parasternal long-axis view with color Doppler.
Echocardiographic 2-dimensional image of the CoreValve in parasternal short-axis view, with and without color Doppler.

The 18F introducer sheath is then removed and the access site closed using percutaneous closure devices or surgically in the case of surgical cutdown. Using a 5F pigtail catheter from the contralateral side, angiography of the primary iliac and femoral arteries is performed to rule out any potential vascular complications.

The pigtail catheter is removed over a standard J-tip guidewire, the 6F introducer sheath removed, and the access site closed.

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Transcatheter Aortic Valve Replacement - Edwards SAPIEN Valve

The Edwards SAPIEN valve may be implanted via a TF or TA approach.

Edwards-Sapien valve transfemoral and transapical Edwards-Sapien valve transfemoral and transapical approaches

Transfemoral approach

Vascular access

After the side of access for the prosthetic valve sheath is decided, the artery on that side is cannulated percutaneously or via surgical cutdown. Femoral access is also obtained on the contralateral side for aortic angiography using a 5F-6F pigtail catheter. A 6F venous access is also obtained for a temporary pacemaker lead, which is used for rapid ventricular pacing. If vascular access is obtained percutaneously for the valve delivery sheath, it can be preclosed with 2 suture-mediated closure devices. If a surgical cutdown is performed, the common femoral artery should not be dissected completely in the posterior aspect, as sheath insertion is easier when the artery is partially anchored.

Temporary pacemaker insertion

A temporary ventricular stimulation lead is placed in the right ventricle. Appropriate capturing is ensured, and a rapid ventricular pacing test is performed at a rate of 180-220 beats per minute.

Aortic angiography

Ascending aortic angiography is performed in a projection that places all of the aortic cusps in line and perpendicular to the image intensifier. Ideally, the projection is previously determined to minimize radiation and contrast exposures.

Crossing the native valve

At this point, intravenous heparin is administered, and once the ACT is confirmed to be therapeutic, the aortic valve is crossed as described above (see Crossing the native aortic valve).

Insertion of delivery sheath

The inserted 8F arterial sheath is then removed, maintaining the guidewire position in the apex of the left ventricle; then, serial dilation of the common femoral artery is performed with arterial dilators of increasing size (16F-25F). This is followed by insertion of the delivery sheath and positioning of the tip in the descending aorta.

Balloon aortic valvuloplasty

Under rapid ventricular pacing, balloon valvuloplasty of the native aortic valve is performed as described above (see Balloon aortic valvuloplasty). A 20- or 23-mm retroflex balloon is used for implantation of the 23- or 26-mm Edwards SAPIEN bioprosthesis.

Edwards SAPIEN valve implantation

The prosthetic valve and the delivery system are inserted through the sheath over the extra-stiff guidewire while the wire position is maintained in the left ventricle. When the delivery system reaches the aortic arch, the retroflex catheter is activated to allow safe passage of the valve delivery system across the aortic arch, and the system is then advanced into the ascending aorta.

The Edwards SAPIEN valve is then positioned in the aortic position, maintaining a 60:40 ratio of ventricular-aortic positioning, in the predetermined reference projection with the aortic annulus situated perpendicular to the screen. The appropriate valve position is confirmed using angiography and echocardiography.

Rapid ventricular pacing is started, and, after the systolic blood pressure has reached and maintained at its nadir, the aortic valve is deployed. Balloon inflation is held 3-5 seconds before deflation, and the rapid pacing is then stopped to avoid traction on the valve while the balloon catheter is being withdrawn. At this point, the delivery system is straightened and withdrawn. Paravalvular leaks are evaluated with echocardiography and angiography, and the transvalvular gradient is measured.

Simultaneous left ventriclular and ascending aorti Simultaneous left ventriclular and ascending aortic pressure tracings before and after TAVR

Arterial sheath removal

The sheath is removed with close monitoring of blood pressure and simultaneous contrast administration through a pigtail catheter placed at the level of iliac bifurcation. Contrast extravasation or significant hypotension indicates vascular rupture, which should be treated immediately using a covered stent or surgery. Prior to surgical arterial repair, emergent tamponade of the ruptured vessel using a large size sheath and/or closure of the iliac artery or abdominal aorta with a large size balloon is performed.

Closure of the arteriotomy site

The arteriotomy site is closed surgically or percutaneously with the previously placed preclosure device(s). With the new-generation Edwards SAPIEN XT device, preclosing with a single 10F device can be performed.

Transapical approach

In the TA approach, femoral arterial and venous access is obtained for aortic root angiography and temporary pacemaker placement for rapid ventricular pacing, as described above (see Venous access).

A small left lateral thoracotomy is performed, the subcutaneous tissue is dissected until the left ventricular apex is visible, and a pursestring suture then is placed in a muscular segment of the apicolateral wall. Heparin is then administered, and, once the ACT is confirmed to be in the therapeutic range, a direct puncture of the left ventricle is performed and a 7F or 8F sheath is inserted directly into the left ventricle.

A 0.035-inch J-tip guidewire is advanced into the descending aorta through the native aortic valve while being guided with a Judkins right catheter. It is important to ensure the wire is free of the papillary muscles or mitral chordal structures to avoid complications with the insertion of the delivery sheath.

After the wire is advanced into the descending aorta, it is exchanged for an extra-stiff Amplatz 0.035-inch 270-cm–long guidewire, and the Judkins right catheter is removed. At this point, the sheath is exchanged for a 26F delivery sheath that is inserted 3-4 cm into the left ventricle. Using a 20-mm retroflex balloon, BAV under rapid ventricular pacing is performed.

The Ascendra delivery system is advanced into the sheath and de-aired. The valve-catheter ensemble is then advanced into the aortic position, maintaining a ratio of 50:50 aortic-ventricular positioning. The optimal position of the prosthetic valve is confirmed using echocardiography and angiography guidance.

The aortic valve is deployed under rapid ventricular pacing when blood pressure is at its nadir and during a patient breath-hold, and the balloon is then deflated and removed. The degree of aortic regurgitation and valve position are evaluated with TEE guidance.

Postdilation of the valve may be performed as indicated.

If no further interventions are required, the delivery sheath is removed, the access site repaired, and anticoagulation reversed. The left lateral thoracotomy site is closed surgically over a drain. [9, 22, 25]

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