Left Ventricular Dilatation and Posterior Papillary Muscle Displacement in an Ex Vivo Pulsatile Model of Functional Mitral Regurgitation

Abstract

<jats:p>Background: Surgical method of choice for functional mitral regurgitation (FMR) is debatable, since recurrence of FMR post-annuloplasty has been reported in a significant number of cases. Developing a pulsatile FMR heart model by left ventricular dilatation can be a favorable option for usage in the primary stages of developing new surgical techniques that adjunctively targets the posterior papillary muscle (PPM) geometry.Methods: PPM of ex vivo ovine hearts (N = 22) was displaced by three different sizes of patches to induce left ventricular dilatation and FMR. Mitral regurgitation (MR) flow, left ventricular and annular geometry were measured from the dynamic pulsatile flow system before and after patch placement.Results: Outward displacement of PPM was significantly increased in all patch sizes compared to baseline (P = .016, P = .031, and P = .008 from small to large patch, respectively). Left ventricular volume (LVV) significantly increased from 18.53 (15.01-26.03) mL at baseline to 27.5 (19.45-42.46) mL after large patch placement (P = .031). However, the small and medium patch groups did not show significant changes in the LVV after patch placement. MR significantly increased 554 (185-1,919.3) mL/min after applying the large patch compared to baseline (P = .016). There were no significant changes from baseline in MR flow after applying the small and medium patch. Application of the large patch produced the highest proportion of FMR heart models (87.5%, P = .031).Conclusion: The large patch ex vivo pulsatile heart model demonstrated outward displacement of the PPM and significantly produced MR flow. This ex vivo pulsatile heart model can be used to facilitate surgical techniques that targets the PPM displacement in FMR patients.</jats:p>

Repairable ex vivo model of functional and degenerative mitral regurgitation

“…Moreover, achieving sufficient dilation of healthy heart samples, especially hypertrophic swine hearts, is often difficult when used as a whole heart with all the supporting tissues remained [ 15 ]. Several previous studies have reported FMR production [ 9 , 12 , 14–16 ]; however, none of them produced sufficient MR that fulfils the interventional indication. Jaworek et al [ 13 ] produced an FMR model by dilating the annulus and LV by pressurizing the LV with a continuous flow pump after clamping the aorta.…”

Epicardial Posterior Papillary Muscle Repositioning with Mitral Annular Reduction for FIMR Treatment: Initial Ex Vivo Heart Model Study

“…The LV wall around the PPM was sutured closed with a 3 cm diaphragmatic patch; this creates a focal dilation of the LV wall and cause outward displacement of the PPM. Kradangnga et al [Kradangnga 2018] studied the ex vivo pulsatile heart model of functional mitral regurgitation and showed that the 3 cm crescent-shaped diaphragmatic patch size placement induced the highest heart models with MR and also produced the highest MR volume. From this data, the 3 cm patch was used to increase the length of the LV wall at the level of the PPM.…”

“…Six intracardiac 2 mm piezo-electric crystals (2 mm round piezo-electric crystals, Sonometrics, London, Canada) were sutured to 6 mitral apparatus landmarks as illustrated in the Kradangnga et al study [Kradangnga 2018]. Nine crystal pairs were of interest and used for the LVV calculation and analysis of the annular and papillary muscles geometry (Table 1).…”

“…The heart was mounted on a pulsatile pressurization system (Bio-console 520D Centrifugal Blood Pump, Bio Medicus, Minnesota), which generated pulsatile flow. We used the same setting of the pulsatile pressurization system as stated in a previous study [Kradangnga 2018]. The LVPmax was maintained at 120 ± 5 mmHg.…”