Introduction
Bioprosthetic valves and atrio-ventricular valve annuloplasty rings are increasingly used because the need for anticoagulants essential for mechanical valves to avoid thrombosis can be obviated. However, these valves are prone to degeneration and significant stenosis and/or regurgitation may occur within a decade of implantation.1 Annuloplasty rings have also failed resulting in significant valvular or para-ring regurgitation. Repeat surgery in these patients who are often elderly and have other comorbidities such as chronic renal failure carries a high mortality.2 Because of this, procedures requiring minimal, or no surgery have come into vogue. One such approach is transcatheter prosthetic mitral valve (MV) implantation in previously surgically implanted degenerated bioprosthetic mitral valves or rings using the transapical or transseptal approach.3,4These approaches have proven successful in the short term and in some studies over the long-term.5,6 It is well known that the presence of intracardiac thrombus is a contraindication to these transcatheter procedures because of fear of thrombus fragmentation and dislodgement resulting in systemic embolization. This represents a challenge for severely symptomatic patients with degenerated mitral prosthetic valves or rings and thrombus in the left atrial appendage (LAA)/left atrium (LA) body who are at high or prohibitive risk for redo MV surgery or refuse surgery. In the present study, we present our experience in these patients in utilizing two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) to carefully bypass the thrombus without disrupting it in any way during transcatheter MV in bioprosthetic MV/mitral ring implantation using the apical approach. This procedure carefully performed under the guidance of 2D and 3DTEE as well as fluoroscopy resulted in no embolic or other complications during the procedure or in the follow up period.
Materials and Methods (Figures 1A-C, 2A-C, 3A-B, 4A-C and 5A-B. Movies 1A-Q, 2A-E, 3A-E, 4A-E, 5A-I).
In our medical center between 2016 and 2021, a total of 80 adult patients have undergone transcatheter MV in surgically implanted bioprosthetic MV with degeneration resulting in severe stenosis or regurgitation (77 patients) or in severely stenotic native MV with a surgically inserted mitral annuloplasty ring for severe MV regurgitation (3 patients) using the apical approach. Of these, 68 patients had no thrombus in the LAA or LA body. The remaining group of 12 patients (8 females, 4 males, mean age 65.6 years, range 55 to 78 years) with thrombus in LAA, LA body or both form the basis of our study. All were severely symptomatic (New York Heart Association, NYHA, functional class III or IV) with severe bioprosthesis MV stenosis in 9 and severe mitral regurgitation in 2 patients by two-dimensional transthoracic echocardiography (2DTTE). The remaining patient had severe native mitral valve stenosis status post a surgically inserted Sorin (Sorin Group USA, Inc. CO, USA) mitral annuloplasty ring for severe MV regurgitation 4 years previously. One of these 12 patients had a second transcatheter MV in bioprosthetic MV procedure following re-development of severe bioprosthetic MV stenosis and thrombus in LAA 2 years and 8 months after the first procedure. Thus, these 12 patients underwent 13 transcatheter MV in valve procedures. All patients had serious comorbidities which presented a high or prohibitive risk for redo surgery and all refused surgery (Table 1).7 The decision to go ahead with transcatheter MV implantation in these circumstances was made by a multidisciplinary team consisting of cardiologists, anesthesiologists and cardiac surgeons.
During the procedure, all patients underwent 2DTEE and 3DTEE using a Philips (Philips Ultrasound Inc, Bothell, WA, USA) EPIQ 7 system and an x7-2t or x8-2t transducer The mean pressure gradient across the degenerated bioprosthetic MV by 2DTEE ranged from 10 and 24 mmHg and the MV orifice area by planimetry using 3DTEE ranged from 0.56 to 1.09 cm2 in all patients with stenosis. In the 2 patients with bioprosthetic MV regurgitation, the vena contracta areas by 3DTEE were 1.25 cm2 and 0.44 cm2, respectively, indicative of severe regurgitation. Eight patients had thrombus by both 2D and 3DTEE in the LAA extending to the adjacent LA body, three patients had thrombus confined to LAA and the remaining patient had thrombus located in the LA body only. In the patient with a second procedure, the thrombus was confined to LAA. In all patients including the patient with a redo procedure, the thrombus was larger by 3DTEE as compared to 2DTEE with the thrombus area ranging from 1.39 to 17.74 cm2 by 3DTEE. The thrombus volume by 3DTEE calculated using the TOMTEC (TOMTEC Imaging Systems GmbH, Unterschleissheim, Germany) software ranged from 1 to 26 ml. The thrombus was noted to be mobile in 2 patients and another patient with a fixed thrombus had mobile components. These were detected by both 2D and 3DTEE. Areas of echolucencies within the thrombus consistent with thrombus lysis/dissolution were noted in all patients by both 2D and 3DTEE.8,9 The maximum echolucent area in each thrombus was found to be larger by 3DTEE than 2DTEE (Table 2). Left and right ventricular function and other associated echocardiographic findings in each patient are also listed in Table 2. One patient with a previous successful transcatheter aortic valve replacement was noted to have developed severe prosthetic aortic valve stenosis with a mean pressure gradient of 41 mmHg.
In all patients, systematic and meticulous cropping of 3D datasets was used to comprehensively evaluate as much of the LA and LAA as possible to exclude any additional thrombus or any other structural abnormality which could pose a hazard during the transcatheter procedure. Determination of the size of the prosthetic MV to be implanted and other parameters such as left ventricular outflow tract size were determined using echocardiography and computed tomography scans as described previously.10