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Articles by L Mont
Total Records ( 2 ) for L Mont
  J Solis , D McCarty , R. A Levine , M. D Handschumacher , L Fernandez Friera , A Chen Tournoux , L Mont , B Vidal , J. P Singh , J Brugada , M. H Picard , M Sitges and J. Hung
 

Background— Cardiac resynchronization therapy (CRT) has been shown to reduce functional mitral regurgitation (MR). It has been proposed that the mechanism of MR reduction relates to geometric change or, alternatively, changes in left ventricular (LV) contractile function. Normal mitral valve (MV) function relies on a balance between tethering and closing forces on the MV leaflets. Functional MR results from a derangement of this force–balance relationship, and CRT may be an important modulator of MV function by its ability to enhance the force–balance relationship on the MV. We hypothesized that CRT improves the comprehensive force balance acting on the valve, including favorable changes in both geometry and LV contractile function.

Methods and Results— We examined the effect of CRT on 34 patients with functional MR before and after CRT (209±81 days). MR regurgitant volume, closing forces on MV (derived from Doppler transmitral pressure gradients), including dP/dt and a factor (closing pressure ratio) expressing how long the peak closing gradient is maintained over systole (closing pressure ratio=velocity time integral/MR peak velocityxmitral regurgitation time), and dyssynchrony by tissue Doppler were measured. End-diastolic volume, end-systolic volume, mitral valve annular area (MAA) and contraction (percent change in MAA from end-diastole to midsystole), leaflet closing area (leaflet area during valve closure), and tenting volume (volume under leaflets to annular plane) were measured by 3D echocardiography. After CRT, end-diastolic volume (253±111 versus 221±110 mL, P<0.001) and end-systolic volume (206±97 versus 167±91 mL, P<0.001) decreased and ejection fraction (19±6 versus 27±9%, P<0.001) increased. MR regurgitant volume decreased from 35±17 to 23±14 mL (P<0.001), MAA from 11.6±3.5 to 10.5±3.1 cm2 (P<0.001), leaflet closing area from 15.4±5 to 13.7±3.8 cm2 (P<0.001), and tenting volume from 5.7±2.6 to 4.6±2.2 mL (P<0.001). Peak velocity (and therefore transmitral closing pressure) was more sustained throughout systole, as reflected by the increase in the closing pressure ratio (0.77±0.1 versus 0.84±0.1 before CRT versus after CRT, P=0.01); dP/dt also improved after CRT. There was no change in dyssynchrony or MAA contraction.

Conclusions— Reduction in MR after CRT is associated with favorable changes in MV geometry and closing forces on the MV. It does so by favorably affecting the force balance acting on the MV in 2 ways: reducing tethering through reversal of LV remodeling and increasing the systolic duration of peak transmitral closing pressures.

  J Toquero , J Alzueta , L Mont , I. F Lozano , A Barrera , A Berruezo , V Castro , J. L Pena , M. L Fidalgo and J. Brugada
  Aims

Implantable cardioverter defibrillators (ICDs) are increasingly being used for treatment of ventricular tachycardia (VT)/fibrillation. Inappropriate therapy delivery remains the most frequent complication in patients with ICDs, resulting in psychological distress, proarrhythmia, and battery life reduction. We aim to determine if inappropriate therapies could be reduced by using a morphology discrimination criterion.

Methods and results

We evaluated the performance of the WaveletTM morphology discrimination algorithm (Medtronic, Inc.) independently from other discrimination enhancements (rate onset and interval stability). A non-randomized, prospective, multicenter, and observational study was designed to determine the sensitivity and specificity of the new morphology criterion. Sensitivity and specificity in slow tachycardia with cycle length (CL) between 340 and 500 ms were analysed as a pre-specified secondary endpoint. A total of 771 spontaneous episodes in 106 patients were analysed. Five hundred and twenty-two episodes corresponded to true supraventricular tachycardia (SVT) with ventricular CL in the VT or FVT zone, of which 473 had therapy appropriately withheld. Of the 249 episodes of true VT/FVT, 21 were classified according to the WaveletTM criteria as SVT (specificity: 90.6%; sensitivity: 91.6%). All of them were spontaneously terminated with no adverse clinical consequences. No syncopal episodes occurred. For VTs in the slowest analysed range (CL: 340–500 ms), a total of 235 episodes were studied, yielding a specificity of 95.9% and sensitivity of 83.2%.

Conclusion

WaveletTM discrimination criteria in single-chamber ICDs as the sole discriminator can significantly reduce inappropriate therapy for SVT, not only in the range of VTs in the slowest analysed range (340–500 ms for this study) but also for faster VTs. No significant clinical consequences were found when the algorithm was used, but final data should prompt the use of the algorithm in combination with a high rate time-out feature.

 
 
 
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