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