Novel technique to prevent outflow tract obstruction in transapical transcatheter mitral valve replacement: The MitraCut technique

MitraCut technique to prevent left ventricular outflow tract obstruction.

Central Message.

The MitraCut technique is an effective, safe, and unique surgical approach to prevent left-ventricular outflow tract obstruction in transapical transcatheter mitral valve replacement.

We present a novel technique to prevent left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve replacement (TMVR). Both reported patients were included in a local, prospective observational study (ERB No.: 1959/2020; November 6, 2022) to investigate the single-center outcome after transcatheter atrioventricular valve interventions. Patient 1 was a symptomatic (dyspnea, 4 heart failure hospitalizations) 88-year-old woman with severe degenerative mitral regurgitation (mechanism: A2 flail and moderate mitral annular calcification) (Figure E1) and anatomical contraindications for transcatheter edge-to-edge repair (mean pressure gradient [MPG] 6 mm Hg). The second patient was a 63-year-old, frail (among others: limited mobility due to repeated strokes) man with mixed severe mitral regurgitation (Carpentier IIIa) and previous thoracic endovascular aortic repair (TEVAR) (indication: perforating aortic ulcer in the aortic arch, TEVAR after transposition of the left subclavian artery, and reinsertion of the left vertebral artery), neither suitable for transcatheter edge-to-edge repair (MPG 7 mm Hg) nor for conventional mitral valve surgery due to the position of the proximal landing zone of the TEVAR hindering a conventional clamping of the ascending aorta. After thorough heart team discussions, transapical transcatheter mitral valve replacement (TMVR) with the Tendyne valve system (Abbott Medical) was considered the optimal therapeutic option in both patients. The annular dimensions were suitable for a 33S, low-profile (patient 1) and 29S, low-profile valve (patient 2), revealing an acceptable calculated end-systolic neo-LVOT (patient 1: 298 mm² and patient 2: 296 mm²) (Figure E1). Nonetheless, the preinterventional echocardiographic evaluation indicated a risk for LVOT obstruction due to a long, rather untethered anterior mitral valve leaflet (AML), septal hypertrophy, and subsequent close AML-to-septum-distance in both patients (Figure E1), resulting in the procedural plan to split the AML by the MitraCut technique¹ before TMVR. A neuroprotective deflection filter (TriGuard 3; Keystone Heart) was used due to calcifications in patient 1. A standard transapical access through a left minithoracotomy was performed and the guiding wire was placed in the left atrium after flossing with a pulmonary catheter.² For the MitraCut, a 26Fr Gore DrySeal sheath (W.L. Gore & Associates, Inc) was shortened to 15 cm (Figure 1, A) and brought into the left atrium over the guiding wire. A straight endoscopic scissor (Ceramo HCR, MRT-2; Fehling Instruments) (length: 10 mm, shaft diameter: 5 mm) was inserted through the sheath and aligned (Figure 1, B and C). The sheet was retracted, the scissor was carefully moved in the left ventricle, the AML was caught at the mid-A2 part, and a sharp dissection of the A2 segment was performed in each patient with 1 cut (Figure 1, D and E), thus the transapical TVMR could be performed after removal of the large bore sheath.

Figure E1.

Risk evaluation for left ventricular outflow tract (LVOT) obstruction by 4-dimensional, electrocardiogram-gated computed tomography (A and B) and transesophageal echocardiography (C and D).

Figure 1.

The MitraCut technique: the shortened large-bore sheath, together with the endoscopic scissor (A), were inserted over the guiding wire followed by the crossing of the mitral valve (B), alignment (C), stabilization (D), and final cutting of the A2 segment (E) (arrow). ∗Scissor tips.

Results

The skin-to-skin time was 97 minutes (patient 1) and 60 minutes (patient 2). In patient 1, the interventional result was a trace paravalvular leakage with no LVOT obstruction (MPG 1 mm Hg) despite an anterior motion of the AML (Figure 2, A and C). Patient 2 had a satisfactory TMVR result with no increase of the LVOT gradient (Figure 2, B and D). Both patients were transferred to the normal ward at the first postoperative day and discharged after an uneventful postoperative period at day 11 (patient 1) and day 8 (patient 2).

Figure 2.

Successful valve expansion (A, B) with satisfactory hemodynamic parameters in both treated patients (C, D). LVOT, Left ventricular outflow tract; VTI, velocity time integral; MV, mitral valve; Vmax, maximal velocity; Vm, mean velocity; MaxPG, maximal pressure gradient; MPG, mean pressure gradient; AV VR, aortic valve velocity ratio.

Discussion

The AML as a target to prevent LVOT obstruction in patients undergoing TMVR has been previously approached by the laceration of the anterior mitral leaflet to prevent LVOT-obstruction (LAMPOON) technique.3, 4, 5 Transapical scissor-mediated splitting with the MitraCut technique was safe, effective, short, and highly controllable. In a setting of a preexisting apical access, the MitraCut technique might be superior to LAMPOON due to decreased risk for vascular complications.⁵ Apical access side complications related to the MitraCut technique itself might be unlikely because the guiding sheath is significantly smaller than the inserted valve system (26Fr vs 34Fr). The MitraCut technique might not be suitable for transseptal TMVR.

From our experience, we recommend a complete neuroprotection—also covering the left subclavian artery—in patients with calcifications.¹

Conclusions

The MitraCut technique might be a valuable alternative to the LAMPOON technique and other techniques to prevent LVOT obstruction in patients with transapical TMVR. Further evaluation in a higher-volume study population is anticipated.