Figure 1.

Representative MIRTH Procedure

(A) The posterobasal left ventricular myocardium (black outline) is accessed directly from the coronary sinus (interrupted blue outline) using a needle catheter (white overlay). (B) An “anchor” guidewire (purple arrow) is advanced through the myocardium into the left ventricular cavity where it is ensnared and externalized (orange arrows). This stabilizes subsequent catheters. (C and D) The MIRTH (Myocardial Intramural Remodeling by Transvenous Tether) “navigation” guidewire with chronic total occlusion (CTO) tip (single black asterisk and inset) is steered around the ventricle, ensheathed by coaxial 0.014-inch (white asterisk) and 0.035-inch (double asterisk) microcatheters and guided by fluoroscopy and electrocardiographic radial depth navigation electrograms. Approximate locations of left ventricular (LV) (white dash) and right ventricular (black dash) septal endocardial borders added for orientation. (E) A self-expanding stent retriever (black rectangle) is advanced over the anchor guidewire within the posterior basal myocardium to act as a target and snare for the returning MIRTH navigation guidewire. (F) A completed MIRTH loop within the walls of the left ventricle (green arrows), viewed from apex of the heart, equivalent to a human LAO caudal projection. (G and H) Baseline- and postprocedure LV angiograms of a midventricular-level MIRTH. The traversing guidewire was exchanged for suture and implant and secured and cut with a surgical crimp fastener. Ao = aorta; LAO = left anterior oblique.