**4. Cardiac imaging for paravalvular leak assessment and procedural guidance**

Assessment of PVLs relay first on ultrasounds. Imaging modalities are complementary and multimodality imaging is usual.

#### **4.1 Transthoracic Doppler echocardiography**

TTE is performed as a first-line noninvasive test. It is essential for detection or suspicion of PVLs through direct or indirect signs. Indirect signs include chambers' enlargement and pulmonary pressure elevation. Direct signs consist of visualization of the defect between the annulus and the prosthetic sewing ring, which should be distinguished from an artifact by simultaneous application of color Doppler and identification of the regurgitant jet. The whole circumference of the annulus should be examined carefully, the number, size, and extension of defects are noticed.

TTE can be sufficient, particularly, in anterior aortic PVLs to determine PVL characteristics, however, its sensitivity and precision are weak in mitral PVLs that can be totally missed by TTE due to acoustic shadows.

TTE is fundamental for the assessment of prosthetic valve flows, left and right ventricles and atria sizes and functions, pulmonary pressures, and other valves' status [14–16].

TTE is usually the main test for periodic follow-up.

#### **4.2 Transesophageal Doppler echocardiography**

Two (2D) and Three (3D) dimensional TEE is the reference test for PVL assessment, it is performed after a comprehensive TTE, whether this latter was contributive or not.

TEE is essential for the investigation of mitral PVL, multiple PVLs, and complex ones [14–16] TEE permits to assess accurately the sites of the leaks by exploring the whole circumference of the sewing ring by 2D, 3D, and color Doppler modes. When using 3D imaging a careful gain setting and joint color Doppler imaging are important to eliminate gain dropouts [15].

A double opposite clock face is used to indicate the mitral and aortic PVLs sites. The mitral clock face is divided into septal, posterior, lateral, and anterior dials (**Figure 1**).

The number, shape, area, length, and height of PVLs are determined by 3D TEE [9, 14] which also indicates the defect distance from the ring and the PVL spatial position in relation to the mechanism of the prosthesis. Precise sizing using 3D multiplanar reconstruction is a key to choose an adequate device when a TPVL is indicated. Identification of calcifications and IE signs are important to discuss the feasibility and difficulty of a TPVL or surgical treatment (**Table 2**) [16, 17].

The quantification of the regurgitation is better evaluated by non-orificerelated parameters. In fact, vena contracta and proximal isovelocity methods, are

#### **Figure 1.**

*Schematization of en face view by transesophageal three-dimensional echocardiography. 0, 50, 90, and 130° views: corresponding bidimensional transesophageal echocardiography plans, AV: Aortic valve, IAS: interatrial septum, LAA: left atrial appendage, LMS: left main stem, MV: mitral valve, RCA: right coronary artery, TV: tricuspid valve.*

distorted by the irregular shape and location of the defect, they are rarely useful. The severity of the regurgitation is better appreciated by continuity equation, end-diastolic descending aorta velocity or reversal systolic pulmonary venous flow, cavities' dilatation, and pulmonary pressures. The circumferential extension of the defect is also a useful parameter for the severity of the regurgitation as well as the feasibility of TPVL. These parameters are to consider in parallel with the clinical status of the patient.

2D and 3D TEE are essential for TPVL guidance, especially in mitral PVLs, while TTE and fluoroscopy can be sufficient to guide aortic PVLs closure. The utility of per procedure TEE is depicted in **Table 2**. Septal puncture is guided by biplane (45 and 130°) imaging when an anterograde approach is chosen for a mitral PVL reduction, real-time 3D and zoom mode are used to localize the guides and orient the crossing of the PVL then the right positioning of the occluder device. At crucial time of the procedure, the deploying, orientation, and position of the device are to be verified as well as the mobility of the prosthetic valve and its flow (**Figure 2**). Before the release of the occluder


#### **Table 2.**

*Role of Doppler transthoracic and transesophageal echocardiography in paravalvular leak management.*

device, the residual leak is searched, qualified, and quantified. When significant, it leads to a change of the choice of the device or the indication of a complimentary ad hoc or differed procedure; residual leaks impact the prognosis (**Figure 2**) [16].

Permanent per-procedural monitoring detects at any time of the intervention the occurrence of complications like pericardial effusion or tamponade, embolization of the occluder, impinging, and blocking of the valve.

TEE is important to consider during follow-up if a complication is suspected (i.e., endocarditis, relapse, or extension of PVLs).

#### **4.3 Fluoroscopy**

*Fluoroscopy* is useful to detect rocking prosthetic valves when there is an extensive disinsertion, or an abnormal movement is seen in TTE or TEE. Fluoroscopy is important for TPVL guiding [16].

*Fusion imaging* combines echocardiography and fluoroscopy, is precious to guide the TPVL, it saves intervention time and increase the success rate [17, 18].

#### **4.4 Intracardiac echocardiography**

*Intracardiac echocardiography* is also an innovative mean to guide TPVL. Unlike TEE it allows to get free from general anesthesia. A series of 21 interventions in 18 patients with intracardiac echocardiography help was reported without any complication related to the imaging technique itself and with an acceptable rate of procedural success [19].

### **4.5 Magnetic resonance imaging and cardiac tomography imaging**

*Magnetic resonance imaging and cardiac tomography imaging* are useful in a multimodality imaging approach, which is crucial for aortic post-SAVR or post-TAVR PVLs. *Cardiac tomography-fluoroscopy fusion imaging* was used in experienced teams to achieve more reproducible results, higher success, and better short and long terms

#### **Figure 2.** *Approaches for transcutaneous paravalvular leak closure.*

outcomes. Also, the extension of indications and treatment with the confidence of complex, multiple PVLs (especially aortic PVLs) were allowed [20, 21].
