Biomechanical analysis of neochordal repair error from diastolic phase inversion of static left ventricular pressurization

Figures

• 

  Robotic ex vivo simulation of static pressurization assessment for neochordal repair.

• 

  Video 1. Intraoperative video highlighting the use of static left ventricular pressurization, or the saline test, during neochordal mitral valve repair. Video available at: https://www.jtcvs.org/article/S2666-2507(22)00037-2/fulltext.

• 

  Figure 1. Labeled illustration of mitral valve neochordal repair with static pressurization for post-repair assessment and diastolic phase inversion (DPI). We hypothesize that DPI results in neochord length overestimation, which might lead to a suboptimal repair and reduced hemodynamic performance.

• 

  Figure 2. The study's methods, results, and implications. Experimental design to test the effects of diastolic phase inversion (DPI) of left ventricular geometry after static pressurization for assessment of post-repair mitral valve (MV) competency. Explanted porcine MVs were mounted in our robotic ex vivo simulator with implanted chordal strain gauges (n = 6). Four paired experiments were tested on each valve in the simulator: baseline control, prolapse, DPI repair, and physiologic repair. TEE, Transesophageal echocardiography; FBG, Fiber Bragg Grating; MR, mitral regurgitation.

• 

  Figure 3. Heart simulator experimental setup, from Imbrie-Moore. A, Picture of the image-guided papillary muscle robotic system sewn to papillary muscles of a porcine mitral valve to mimic the motion of the heart. B, Diagram of the custom left heart simulator with stationary papillary muscles during ex vivo cardiac simulation experiments. C, High-resolution Fiber Bragg Grating strain gauge sensor instrumenting a chordae tendineae; the sensor is calibrated to correlate strain to force. The chord is severed between the 2 suture attachment points, denoted by red arrows, to transmit all force through the sensor.

• 

  Figure 4. A, Mean flow tracings for baseline, prolapse, diastolic phase inversion (DPI) repair, and physiologic repair. Flow tracings show successful induction of mitral regurgitation for the prolapse condition followed by restoration of flow dynamics for both repairs. B, Mean pressure tracings for all experimental conditions. Pressure data shows a reduction in pressures for the prolapse condition, indicating successful induction of mitral regurgitation, followed by a return to normal pressures for both repair conditions. Shaded regions for both panels represent standard error.

• 

  Figure 5. A, Mean force tracings for primary and secondary chordae in diastolic phase inversion (DPI) and physiologic repair conditions. A Fiber Bragg Grating sensor was used in each case to measure real-time native chordae forces. Shaded regions represent standard error. On average, the physiologic repair resulted in lower chordal forces than those of DPI repair, with peak force data additionally reflecting that reduction. B, Box plot of combined primary and secondary peak chordal forces for the DPI and physiologic repairs. The upper and lower borders of the box represent the upper and lower quartiles, the middle horizontal line represents the median, and the upper and lower whiskers represent the maximum and minimum values. Lines between points represent paired data. The peak forces were lower (P < .01) for the physiologic repair (0.57 ± 0.11 N) compared with the DPI repair (0.68 ± 0.12 N).