Fig. 5.1
Aortic valve assessment. Transthoracic echocardiogram confirmed aortic bioprosthesis dysfunction with severe aortic regurgitation (a), confirmed on transesophageal echocardiogram (b). A short-axis transthoracic view demonstrated the appearance of a mobile calcified mass (arrow) (c)
In view of her emergency admission with cardiac decompensation in the context of aortic bioprosthesis dysfunction, she was discussed at the “Heart Team meeting.” Due to her high surgical operative risk (Logistic EuroSCORE, 21 %; STS mortality, 11.33 %), it was decided that she would be best treated with transcatheter aortic valve implantation (TAVI).
5.2 Patient Work-Up
Further investigations were carried out to aid in procedural planning. Baseline hematology revealed a normal hemoglobin and platelet count and biochemistry confirmed normal renal and hepatic function. There was no biochemical evidence of ongoing inflammation. Other investigations including carotid Doppler ultrasound and pulmonary function tests were within normal limits.
Computed tomography (CT) confirmed the diameter of the inner ring of the aortic bioprosthesis to be 16.5 mm (Fig. 5.2a, b), the anatomy of the left ventricular outflow tract (LVOT) (Fig. 5.2c), and the position of the mitral bioprosthesis (Fig. 5.2d). The height of the left coronary ostium was 12 mm and the right coronary ostium was 14 mm. Assessment of the peripheral vasculature demonstrated a minimal lumen diameter (MLD) of 6.1 mm on the right and 5.7 mm on the left in the absence of significant calcification or tortuosity.
Fig. 5.2
Computed tomography. Appearance of St. Jude Epic bioprosthetic valve (a). Computed tomography of aortic bioprosthesis (b) and appearance of left ventricular outflow tract (LVOT) (c) and of mitral bioprosthesis (d)
5.3 Factors for Consideration
There were a number of different factors that require careful consideration when determining the optimal procedural strategy for this patient including:
Choice of access site
Device selection for a valve-in-valve (VIV) procedure in the presence of severe aortic regurgitation
Device selection in view of the presence of a mitral bioprosthesis
The requirement of cerebral protection in view of the appearance of a mobile calcified structure on the aortic bioprosthetic valve – a likely consequence of the previously treated episode of endocarditis
5.4 Procedural Planning
5.4.1 Access Site
The default vascular access site is now the transfemoral route, due to a number of advantages including the ability to perform the procedure under sedation, resulting in shorter procedure and recovery times [1, 2]. With improvements in the design of current TAVI transfemoral delivery systems, the currently recommended MLD is >5.5 mm for femoral access. Our patient had favorable femoral anatomy, and therefore, a transfemoral approach was chosen.
5.4.2 Valve-in-Valve Procedure
Redo sternotomy and surgical aortic valve replacement are associated with a mortality of approximately 5 % [3] and may rise to as high as 20 % in elderly patients with multiple comorbidities [4]. The global valve-in-valve (VIV) registry [5] demonstrated that TAVI treatment for bioprosthesis dysfunction is feasible and reported a procedural success rate of 93 % and 30-day mortality of 8.4 %. Our patient had a 25-mm Medtronic Epic valve in situ with an inner ring diameter of 17 mm suitable for a transcatheter VIV procedure.
5.4.3 Device Selection
The correct selection of device is critical to the ultimate success of any TAVI procedure but was even more critical in this case due to the number of different aspects that needed to be considered:
- 1.
VIV procedures as opposed to the treatment of native valves are associated with a higher risk of coronary obstruction [5].
- 2.
The presence of the bioprosthetic mitral valve was an important consideration due to the potential difficulty in obtaining an optimal position of the TAVI device.
- 3.
The small annulus size of the bioprosthetic valve and the concern of a high postprocedural gradient following TAVI [5].
In view of these concerns, we decided to use a Medtronic Evolut R 23-mm device. Firstly, the design of the valve with the constriction zone reduces the likelihood of coronary obstruction. Secondly, as opposed to other devices (e.g., Portico valve), the CoreValve is implanted in a supra-annular position that is associated with lower postprocedural gradients following VIV TAVI [6]. Finally, due to the presence of the mitral bioprosthesis, we were concerned about the possibility of not achieving optimal valve positioning at the first attempt [7]. The ability to reposition and completely resheath the Evolut R device in case of suboptimal position or coronary obstruction was particularly attractive.
5.4.4 Cerebral Protection
The use of cerebral protection devices has been of great interest recently in a bid to reduce the incidence of stroke with effects between 5 % and 7 % of patients at 1-year following TAVI [8], and 80 % of patients suffer silent cerebral injury when measured by magnetic resonance imaging [9]. One such strategy has been the use of cerebral protection devices, and a recent study has demonstrated that the use of the Claret embolic protection device (Claret Medical, Santa Rosa, California, USA) has been associated with a reduction in the volume of ischemic lesions following TAVI implantation [10], although the clinical significance of this finding is currently unclear. In view of the appearance of a mobile calcified lesion on the aortic bioprosthesis, it was felt that the use of a cerebral protection device was indicated and may reduce the risk of an embolic event following valve implantation, accepting that the Claret device does not protect the left vertebral artery.
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