Surgical annuloplasty can potentially hoist the posterior annulus anteriorly, exaggerate posterior leaflet (PML) tethering, and lead to recurrent ischemic/functional mitral regurgitation (MR). Characteristics of leaflet configurations in late postoperative MR were investigated.
In 30 patients with surgical annuloplasty for ischemic MR and 20 controls, the anterior leaflet (AML) and PML tethering angles relative to the line connecting annuli, posterior and apical displacement of the coaptation and the MR grade were measured by echocardiography before, early after, and late after surgery. Early after surgery, grade of MR and AML tethering generally decreased (P<0.01), whereas PML tethering significantly worsened (P<0.01). Nine of the 30 patients showed recurrent/persistent MR late after surgery. Compared with patients without late MR, those with the MR showed similar reduction in the annular area, significant re-increase in posterior displacement of the coaptation, and progressive worsening in PML tethering (P<0.05) late after surgery in comparison to the early phase. Both preoperative MR and late postoperative MR were significantly correlated with all tethering variables in univariate analysis. Although apical displacement of the coaptation was the primary determinant of preoperative MR (r2=0.60, P<0.0001), increased PML tethering was the primary determinant of late MR (r2=0.75, P<0.0001).
Whereas both leaflets tethering is related to preoperative ischemic MR, both leaflets tethering but with predominant contribution from augmented and progressive PML tethering is related to recurrent/persistent ischemic/functional MR late after surgical annuloplasty.
"However, annuloplasty alone cannot provide a survival benefit for those with LV dysfunction , and is associated with a high prevalence of late recurrence of MR , which is an important predictor of mortality after surgery for ischemic MR . Reduction annuloplasty may exaggerate posterior leaflet tethering due to an anterior shift of the posterior annulus by the ring and result in recurrence of MR late after the annuloplasty . Thus, the mitral valve procedure alone could be insufficient to treat ischemic MR because this is a ventricular disease rather than a valvular disease, and additional ventricular and submitral procedures could be beneficial. "
[Show abstract][Hide abstract] ABSTRACT: Background
Since reduction annuloplasty alone for ischemic mitral regurgitation (MR) cannot prevent late recurrence of MR or improve survival for those with left ventricular (LV) dysfunction, and the surgical approach to this etiology is still controversial, we conducted a study to assess the efficacy of the additional papillary muscle approximation (PMA) procedure for ischemic MR by comparing the different subtypes of PMA.
We studied 45 patients who underwent mitral annuloplasty and papillary muscle approximation (PMA) for ischemic MR between 2003 and 2012. Papillary muscles were approximated entirely (cPMA: complete PMA, n = 32) through an LV incision or partially from the tips to mid-parts (iPMA: incomplete PMA, n = 13) through the mitral and aortic valves. Twenty-three patients with cPMA also underwent LV plasty (LVP). We assessed the outcomes after PMA by comparing cPMA and iPMA.
The baseline MR grade, NYHA class, LV end-diastolic diameter, and LV ejection fraction (LVEF) were 2.8 ± 1.0, 3.2 ± 0.6, 67 ± 6 mm, and 30 ± 10%, respectively. There were no significant differences in these parameters among those with iPMA, cPMA/LVP-, and cPMA/LVP+, though iPMA patients had better LVEF than others. Three patients died before discharge and 12 died during the follow-up. Recurrence of grade 2+ and 3+ MR occurred in 8 and 2 patients, respectively. Reoperation for recurrent MR was performed only for the 2 patients with recurrence of grade 3+ MR. The cPMA was associated with lower mortality (log-rank P = 0.020) and a lower rate of recurrence of MR ≥2+ (log-rank P = 0.005) than iPMA. In contrast, there were no significant differences in the mortality (log-rank P = 0.45) and rate of recurrence (log-rank P = 0.98) between those with cPMA/LVP- and cPMA/LVP+. The 4-year survival rate and rate of freedom from recurrence of MR ≥2+ were 83% and 85% for those with cPMA, repectively. In contrast, the rates were 48% and 48% for those with iPMA, respectively.
Complete PMA could be associated with lower postoperative mortality and higher durability of mitral valve repair for ischemic MR.
Journal of Cardiothoracic Surgery 06/2014; 9(1):98. DOI:10.1186/1749-8090-9-98 · 1.03 Impact Factor
"Repair failure after undersized annuloplasty results from progressive leaflet tethering and LV dysfunction, implicating a maldistribution of annular and subvalvular stresses as a probable mechanism (McGee et al., 2004; Kuwahara et al., 2006). While an array of annuloplasty rings is commercially available, no consensus exists for which rings may be best for a severely distended LV (Braun et al., 2012). "
[Show abstract][Hide abstract] ABSTRACT: Mitral annuloplasty has been a keystone to the success of mitral valve repair in functional mitral regurgitation. Understanding the complex interplay between annular-ring stresses and left ventricular function has significant implications for patient-ring selection, repair failure, and patient safety. A step towards assessing these challenges is developing a transducer that can be implanted in the exact method as commercially available rings and can quantify multidirectional ring loading. An annuloplasty ring transducer was developed to measure stresses at eight locations on both the in-plane and out-of-plane surfaces of an annuloplasty ring's titanium core. The transducer was implanted in an ovine subject using 10 sutures at near symmetric locations. At implantation, the ring was observed to undersize the mitral annulus. The flaccid annulus exerted both compressive (-) and tensile stresses (+) on the ring ranging from -3.17 to 5.34MPa. At baseline hemodynamics, stresses cyclically changed and peaked near mid-systole. Mean changes in cyclic stress from ventricular diastole to mid-systole ranged from -0.61 to 0.46MPa (in-plane direction) and from -0.49 to 1.13MPa (out-of-plane direction). Results demonstrate the variability in ring stresses that can be introduced during implantation and the cyclic contraction of the mitral annulus. Ring stresses at implantation were approximately 4 magnitudes larger than the cyclic changes in stress throughout the cardiac cycle. These methods will be extended to ring transducers of differing size and geometry. Upon additional investigation, these data will contribute to improved knowledge of annulus-ring stresses, LV function, and the safer development of mitral repair techniques.
Journal of Biomechanics 08/2013; 46(14). DOI:10.1016/j.jbiomech.2013.07.013 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The maximum-likelihood (ML) receiver structure is derived for the
detection of digital data symbols transmitted using a four-dimensional
signalling scheme in the presence of intersymbol interference and
additive white Gaussian noise. The transmitter employs
quadrature-quadrature phase-shift keying (Q<sup>2</sup>PSK) which is a
relatively new spectrally efficient modulation scheme and can be
considered as two minimum-shift-keying type signalling schemes in
parallel. The implementation of this receiver is discussed and an
artificial neural network capable of computing the maximum-likelihood
estimate of the transmitted sequence is described. Mapping of the
derived objective function onto the artificial neural network structure
is carried out and a neural network based receiver is presented.
Preliminary simulation results are also presented showing promising
error rates for several intersymbol interference durations with and
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