Technique
Benefit
Zoom mode + CD acquisition of small volume of tissue containing PVL channel only
Highest possible volume rate
Single-beat acquisition only
Avoidance of stitching artifacts
Multiplanar presentation
Measurements of CSA of VC, minimum and maximum dimensions of VC, channel length
Fig. 5.1
CD-mapped flow across PVL with the identification of true VC (arrow)
Beside the PVL itself, the appearance of adjoining structures should also be appreciated. The close vicinity of protruding calcium deposits or prosthesis’ horns may hinder full expansion of occluding device’s discs and thus deteriorate the completeness of PVL sealing, which is particularly relevant should a paravalvular leak device (PLD) be used.
5.1.3 Echo-Driven Choice of Occluding Devices
From a practical standpoint, it is important to allocate the observed PVL into one of two groups presented in Table 5.2. Such approach is intended to choose optimal occluding devices as described in detail in Chaps. 5 and 9 (either Amplatzer Vascular Plug III—AVP III—implanted in multiplug technique or PLD used a single device). For sizing of PVL channel, RT-3D TEE with CD is usually an excellent tool with previously mentioned limitations related mainly to the location of the lesion. For a multiplug approach, the cross-sectional area (CSA) of the PVL vena contracta (VC) is the key parameter [5]—see Fig. 5.2a, b. Should a PLD be chosen as best anatomy-matched device, minimum and maximum diameters of PVL VC dictate the size of the device without any oversizing [6]—see Fig. 5.3a, b.
Table 5.2
PVL anatomy features relevant for device choice
Suitable for multiplug AVP III | Suitable for single PLD |
|---|---|
Irregular/crescent CSA of VC | Round /oval CSA of VC |
Channel length >5 mm | Channel length ≤5 mm |
Bulks of calcium within channel or surrounding structures that might impede full expansion of discs | No structures potentially impeding disc apposition |
Fig. 5.2
Measurement of cross-sectional area (CSA) of VC in mitral (a) and aortic (b) PVL
Fig. 5.3
Measurement of maximum and minimum diameters of VC (D1, D2) and length of the channel (D3) in mitral (a) and aortic (b)
5.1.4 Technical Tips
To achieve the best attainable quality of imaging, the most rudimentary technical aspects also need to be taken into account. The first difficulty may be caused by the patient’s position during the procedure (horizontal as opposed to left lateral during standard TEE examination). In some patients, it significantly deteriorates the quality of the image. Placing a pillow under patient’s right shoulder blade and thus regaining more TEE-friendly heart position within the chest can solve the problem. Long time of procedure may also be of consequence due to gradual drying out of the esophagus. This problem may easily be prevented in most cases by regular use of rubber sheaths for TEE probe amply filled with saline or ultrasound gel.
5.2 Echocardiographic Guidance for Specific PVL Location
Echocardiographic determination of PVL location, discussed in detail in Chap. 4, is pivotal for the choice of the access site. Likewise, the chosen approach for TPVLC poses specific challenges for echocardiography guiding.
5.2.1 Para-aortic Leak: Transvascular Access
In majority of patients, the PVL can usually be easily identified and crossed on fluoroscopy provided the location is known from echo. Thus, in many patients, 2D TEE may be sufficient for TPVLC guiding. Given friendly anatomy, on standard short and long axis (SAX, LAX) views with CD, the CSA of PVL’s VC, minimum and maximum dimensions, and the channel length can be measured with satisfying precision. If the PVL channel is oblique, RT 3D TEE with CD may visualize the course of the channel and identify the true VC dimensions. During TPVLC, performed in a retrograde manner from transfemoral arterial access, constant echo surveillance is needed to identify potential reasons for complications. First, after forming the loop in the left ventricle (LV), the tip of the guidewire may migrate across the mitral valve into LA increasing the risk of tamponade if unobserved. Secondly, retraction of partially opened occluders before their implantation may result in mitral subvalvular apparatus impingement and chordal rupture unless timely identified—Fig. 5.4. If a PLD is used, 3T 3D TEE may visualize the plug’s distal disc within the left ventricular outflow tract (LVOT) and thus be helpful in orientating the device properly. After full expansion of occluding devices but before their release, the mobility of prosthetic discs has to be verified, with 2D TEE being usually an excellent tool. Both 2D and 3D TEE are useful for assessment of TPVLC effect as described below.
