Mitral stenosis remains a critical driver of atrial fibrillation and pulmonary hypertension.¹ However, there is a lack of animal models that faithfully reproduce this human pathology.² Here, we describe a novel transcarotid wire‐induced mitral stenosis (TWIMS) mouse model developed in accordance with institutional guidelines with approval by the Institutional Animal Care and Use Committee of University of Missouri (Approval #40285). The data, analytic methods, and study materials supporting the findings of this study are available from the corresponding author upon reasonable request.

TWIMS uses a closed‐chest, retrograde transcarotid approach guided by B‐mode echocardiography (Figure 1A and 1B). Four‐month‐old mice were used to balance technical feasibility, procedural reproducibility, and postoperative survival. A tip‐curved guide wire (G02426 RX, Cook Medical Inc.; shaped as depicted in Figure 1A) was introduced into the right common carotid artery via blunt dissection. The guidewire was advanced to aortic root; upon encountering tactile resistance, the operator used a standardized “rotate‐and‐advance” maneuver coordinated with systole to safely cross the aortic valve. Once within the left ventricle, the external shaft of the wire was deflected laterally, using a levering action to direct the intracardiac tip toward the mitral annulus. Following visual confirmation of leaflet contact, controlled injury was delivered via 100 translational and rotational passes to ensure endothelial disruption on the mitral leaflets.