Fig. 4.1
Occlutech® paravalvular leak device (PLD), manufactured by Occlutech Holding, Switzerland: illustrations of the technical characteristics of the square shaped and rectangular shaped in the two different disc connections
Fig. 4.2
Pictures of the two different shapes (above) and the two different disc connections (below) of the Occlutech® PLD
Fig. 4.3
Occlutech® PLD. (a) Red circles and arrows show the two gold radiopaque markers to secure device positioning; (b) representative pictures of PLD square (left) and of PLD rectangular (right): pictures from left to right show the view from the proximal disc, side view, and view from the distal disc, respectively
The Occlutech® PLDs are available in sizes ranging from 3 to 7 mm (square designs) that require 6–7 Fr sheaths and from 4 × 2 to 18 × 10 mm (rectangular designs) that require 5–10 Fr sheaths for delivery (Figs. 4.4 and 4.5). The device can be delivered, at the physician’s choice, either via transapical or endovascular routes.
Fig. 4.4
Occlutech® rectangular PLD: recommended delivery systems and devices sizes. W and T represent the types of connections between the discs. W stands for waist (D3 or A × B); T stands for twist (connection diameter is negligible) * and ** = Availability subject to regulatory approval
Fig. 4.5
Occlutech® square PLD: recommended delivery systems and devices sizes. W and T represent the types of connections between the discs. W stands for waist (D3 or A × B); T stands for twist (connection diameter is negligible) * and ** = Availability subject to regulatory approval
Both rectangular and square designs have 35% less surface area as compared to a similar sized, circular design. This reduces the possibility of mechanical interference with a valve and minimizes device overlap in case multiple Occlutech® PLDs are needed to seal a leak.
Moreover, due to the waist designs, the Occlutech® PLD has no radial strength, but it has an intrinsic clamping force that keeps the prosthetic valve and tissue in close proximity to each other after PVL closure. In contrast, vascular plugs of Amplatzer family have high radial strength (large waists) and lack the clamping force (e.g., Amplatzer Vascular Plug III).
The Occlutech® PLD wire braiding ends in a welded ball on the proximal side of the device. This ball serves as adapter for the pusher cable (Flex Pusher, manufactured by Occlutech Holding, Switzerland, Fig. 4.6a, b). To connect an Occlutech® PLD to the Flex Pusher, the handle of the pusher is pulled back to open the jaws located at the distal end of the wire. Release of the handle causes the jaw to close around the ball adapter thus attaching the pusher wire to the device. Once attached, the connection is secured by means of actuating a screw (locking mechanism) on the handle of the pusher to prevent accidental or premature release of the device (Fig. 4.6c). After the Occlutech® PLD has been positioned optimally in the PVL area, the device can be disconnected from its pusher cable by loosening the locking mechanism and releasing the handle (Fig. 4.6d).
Fig. 4.6
(a) The Flex Pusher and PLD: the handle of the cable untightened (left upper); Flex Pusher connected to PLD (right upper); to prevent premature release of the device, the handle of the cable is tightened acting as a security mechanism (below). (b) On the proximal side of the PLD, the wire braiding ends in a welded hub which connect to the distal part of the Flex Pusher in a socket sleeve, somewhat similar to a bioptome. (c) The Flex Pusher connected to the PLD and locked. (d) The handle of the cable is untightened in order to release the device by pushing the handle, once the PLD is in good position
4.3 Implantation Procedure
Transcatheter PVL closure device delivery techniques vary significantly among physicians and/or centers. Notwithstanding, the procedure is performed in a hybrid operating room with the patient under general anesthesia and using fluoroscopic and transesophageal echocardiographic (TEE) guidance (see Sect. 4.4).
On the day of the procedure, standard endocarditis prophylaxis (e.g., second- to fourth-generation cephalosporin) is administered. Patients are anticoagulated with 60–100 IU of unfractionated heparin/kg to achieve an activated clotting time (ACT) of ≥250 s.
4.3.1 Mitral Paravalvular Leaks
General considerations:
- 1.
Mitral PVL repair is technically more demanding when compared to aortic PVL, and close cooperation between the imaging team and interventionalists is of paramount importance. Due to the extensive manipulation in the left atrium, generous anticoagulation should be administered (e.g., ACT ≥ 300 s).
- 2.
A careful preprocedural analysis of leak size, number, and location using 2D/3D TEE and 4D computed tomography angiography (4D-CTA) should be performed. When selecting the size of the device, it is highly recommended not to oversize the occluder in order to avoid excessive distortion of the device and interference with the neighboring structures.
- 3.
For laterally located leaks (9–11 o’clock, Figs. 4.7 and 4.8), an anterograde approach should be taken. Transseptal puncture is a key step in this approach. After positioning of the delivery sheath in the right femoral vein, a transseptal puncture is performed by maneuvering a 5 Fr multipurpose catheter via a steerable/deflectable sheath. Next, the mitral paravalvular leak is crossed from the left atrium into the left ventricle. The Occlutech® PLD can now be advanced using a delivery sheath, and the leak can be closed.
- 4.
For anteriorly located leaks (12–1 o’clock, Fig. 4.8 and 4.9a), a retrograde approach can be useful. A catheter is inserted into the femoral artery and guided through the left ventricle into the left atrium using a Judkins Left or Right catheter. A hydrophilic wire is then used to trans-navigate the leak and to cross into to the left atrium. Frequently, this wire needs to be snared and exteriorized from the femoral vein; thus, an arteriovenous loop to advance the sheath from the femoral vein (anterograde) should be established. The Occlutech® PLD can now be advanced using a delivery sheath, and the leak can be closed.
- 5.
The transapical route (Fig. 4.9b) is our preferred approach, particularly for anteromedially, posteromedially, and posterolaterally located leaks (2–8 o’clock, Fig. 4.7). This procedure requires a limited thoracotomy that is performed by a cardiac surgeon. Once the left ventricular apex has been identified, the left ventricle is punctured in a position parallel to that of the leak. A short sheath is inserted into the left ventricle, the leak is crossed, and the sheath is placed into the left atrium. The Occlutech® PLD can now be advanced using a delivery sheath, and the leak can be closed.
Fig. 4.7
Mitral valve clockface. Recommended approaches for transcatheter PVL closure based on the location of the leaks
Fig. 4.8
Antegrade approaches for closing prosthetic mitral PVLs. Advantages and disadvantages
Fig. 4.9
Retrograde approaches for closing prosthetic mitral PVLs. (a) Retrograde from aorta-left ventricle; (b) retrograde transapical. Advantages and disadvantages
4.3.2 Aortic Paravalvular Leaks
General considerations:
- 1.
Generally, percutaneous aortic PVL repair is not technically difficult, and it should be considered as the first therapeutic option in these patients as opposed to surgery.
- 2.
Aortic PVLs are most often located near the non-coronary sinus, and percutaneous repair of aortic PVLs is feasible in most patients (Fig. 4.10).
- 3.
Two-dimensional color Doppler and real-time 3D TEE are necessary. Angiography of the ascending aorta in different planes is used to define the location of the aortic leak and to guide the procedure and validate the outcomes.
- 4.
A retrograde approach (via the femoral artery) is the most common route of intervention. In some cases, a retrograde transapical approach may also be used particularly in cases of calcified, tortuous, and elongated aortic arch and thoraco-abdominal aortic aneurysm. In this abovementioned setting of patients, even a retrograde trans-aortic approach (via the subclavian artery) represents an alternate route of intervention. Brachial access can be also used and may become a more established procedure used with the Occlutech® PLD in the near future (Fig. 4.11).
- 5.
Access through the leak can be accomplished by first using a multipurpose catheter and a hydrophilic wire. Once the leak is crossed, the hydrophilic wire is exchanged for a 0.035-in. stiff wire with a soft tip. This latter wire is introduced and placed to rest in either the left ventricle (retrograde approach) or in the ascending aorta (transapical approach). The Occlutech® PLD can now be advanced using a delivery sheath, and the leak can be closed.
Fig. 4.10
Aortic valve clockface with corresponding TEE imaging and a schematic pattern. Aortic PVLs are most often located near the non-coronary sinus
Fig. 4.11
Retrograde approaches for transcatheter closure of aortic PVLs. (a) Retrograde trans-aortic from femoral artery; (b) retrograde transapical; (c) retrograde trans-aortic from subclavian artery. Subclavian artery approach could be an alternative second-choice access in cases of severely calcified, tortuous, and elongated aortic arch and thoraco-abdominal aortic aneurysm
4.4 Pre-, Intra-, and Postprocedural Imaging (See Cases Illustrations)
Although echocardiography is the technique of choice to identify and quantify PVL, additional preprocedural imaging modalities such as ECG-gated computed tomography with three- or four-dimensional (3D/4D CT) reconstruction and magnetic resonance imaging (MRI) scan can be useful providing further details regarding leak’s location, number, size, shape, and spatial orientation (planning for transapical access), width and length of the channel, and the assessment of regurgitant volumes.
Performing catheter-based procedures requires the use of numerous imaging modalities and techniques. Thus, access to adequate imaging tools is the cornerstone for making a proper diagnosis, for intraprocedural monitoring, and for assessing and follow-up of postprocedural results.
Accurate, imaging-based assessment of PVL anatomy is a prerequisite, and the use of fluoroscopic imaging is imperative. Orthogonal fluoroscopy views of multiple planes are needed to assure accurate wire placement and PVL closure. Bioprosthetic or mechanical prosthetic valves may be used as reference points during the entire procedure.
Having a comprehensive view of the PVL is crucial for adequate device selection and to determine the best route for implantation. 2D/3D TEE imaging can be used to localize the leak and to assess the number, size, and shape of leaks. Real-time 3D TEE provides more accurate morphological information compared to 2D TEE.
While color Doppler-based imaging modalities to detect and grade regurgitant jet volume are most often used to diagnose and assess the severity of PVLs, TEE is recommended as the most sensitive method. 3D TEE imaging used alone, or used together with 3D color Doppler imaging, is highly accurate to locate PVLs.
In practice and for the ease and clarity of communication among specialists, it is recommended to record the location of a PVL in clockwise fashion from a surgeon’s perspective of the valve (Figs. 4.7 and 4.10).
Selecting the right size and shape of an Occlutech® PLD depends on the anatomy of the leak. Images acquired from 2D, 3D, color Doppler, and TEE imaging modalities should be combined to detail the cross-sectional configuration of PVLs (oval, round, or crescent shaped) as well as the shape and length of the leak (flat or tunnel-like).
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