Case Presentation
The child’s weight was 38 kg, her height was 1.48 m, 32th percentile according to the Centers for Disease Control and Prevention (CDC) growth charts.. An examination revealed a diastolic rumbling murmur (grade IV/VI) with maximum intensity at the apex and propagation to the axilla. Transthoracic echocardiography showed a degenerated bioprosthetic MV with thickened, calcific, and restricted leaflets. The right ventricle (RV) was severely dilated with significantly depressed function, and the interventricular septum shifted substantially towards the left side (Videos 1 and 2). The aorta-MV angle was 63° (Figure 1A), the left ventricular outflow tract (LVOT) diameter was 19 mm, and the LVOT mean pressure gradient was 5 mm Hg with no septal bulge. Thus, LVOT obstruction was unlikely. Severe mitral stenosis was observed, with a mean pressure gradient of 18 mm Hg (Figure 1B). There was mild tricuspid regurgitation, with an estimated systolic pulmonary artery pressure of 66 mm Hg (Figure 1C). Transoesophageal echocardiography confirmed these findings (Figure 1D and Video 3), and 3D zoom of the MV from the left atrium and left ventricle showed a fusion of the three leaflets (Figure 1E and 1F and Video 4). The heart team deemed her a high risk for surgery due to severe RV dilation, RV dysfunction, and severe pulmonary hypertension. The team thus recommended a transcatheter mitral valve replacement (TMVR).
The procedure was conducted in a standard catheterization laboratory under general anaesthesia and with transoesophageal echocardiography guidance. Right femoral arterial and venous accesses were established, and left venous access 6F for the pacemaker lead was established as a backup. Transseptal access was difficult due to the heavily fibrotic and thick septum. A diathermy pen in cautery mode was applied to the hub of a BRK transseptal needle for 2 seconds, which facilitated septum crossing. A 5-F multipurpose catheter (Cook Medical, Bloomington, IN, USA) was advanced over a standard 0.035-inch guidewire using an Agilis™ catheter (St. Jude Medical, St. Paul, MN, USA). A Glidewire® (Terumo Medical Corporation, Somerset, NJ, USA) facilitated crossing of the mitral valve bioprosthesis (Figure 2A). A stiff, pre-shaped, 0.035-inch Confida Wire (Medtronic, Minneapolis, MN, USA) was positioned in the left ventricle apex. An Armada 35 peripheral 14-mm balloon (Abbott, Santa Clara, CA, USA) was used to dilate the atrial septum (Figure 2B), followed by dilatation of the stenosed valve using the same balloon (Figure 2C and 2D).
An Edwards E-sheath 14F was introduced through the right femoral vein to the level of the hepatic veins. A 23-mm SAPIEN 3 valve was crossed to the left atrial cavity with the Edwards mark facing upside down to improve flexion via the macro knob. Unfortunately, the system loop inside the left atrium failed to cross. We attempted to establish apical left ventricular access to allow for system stability, unfortunately the access was established in the right ventricular apex due to the severe enlargement of the right ventricle. Confida wire was snared through the aortic valve (Figure 2E) to facilitate crossing the bioprosthesis.
After the valve delivery system crossed the degenerated valve, the SAPIEN valve balloon was inflated slowly without need for rapid pacing to enable positioning on 80% of the ventricular and 20% of the atrial valve stent (Figure 2F, Figure 3A, and Video 5). The balloon was inflated an additional 2 ml for ventricular flaring of the SAPIEN valve. A multipurpose catheter facilitated removal of the Confida wire (Figure 3B). Transoesophageal echocardiography evaluation revealed a mean gradient of 5 mm Hg with no valvular or paravalvular incompetence (Figure 3C). 3D imaging showed a well-opened valve (Figures 3D and 3E and Video6). The unintentional RV apical access was closed using an 8-mm Amplatzer Vascular Plug II (St. Jude Medical, St. Paul, MN, USA), as shown in Figure 3F and Video 7. The patient was discharged after 2 days.
At the patient’s 30-month follow-up, her weight was 50 kg, height was 1.5 m, 70th percentile according to the CDC growth charts . She had regular daily activity with no shortness of breath. Transthoracic echocardiography revealed that the RV reduced in size and demonstrated normal functioning in comparison to preoperative images (Figure 4A and 4B and Video 8). Systolic pulmonary artery pressure reduced to 33 mm Hg (Figure 4C), the LVOT mean pressure gradient at LVOT was 10 mm Hg (Figure 4D), and the MV mean pressure gradient was 6 mm Hg (Figure 4E).