| Cardiac resynchronization therapy(CRT) could improve the cardiac function through optimizing the synchronization between atria and ventricles, left ventricle and right ventricle, and intra-left ventricle, resulting in excellent therapeutic effect in the patients with severe heart failure, particularly in the cases with secondary severe MR and prominent widened QRS complicated LBBB. However, about 30% of cases without symptomatic improvement, even progressive deterioration after pacing;it may be caused by incorrect electromechanical resynchronization(EMR). The main reason causing incorrect EMR were as follows: (1) incorrect sites of left ventricular and right ventricular pacing, (2) not optimal A-V interval, and incorrect left ventricular filling, (3) no optimal biventricular synchronized pacing caused by failed to sequential control the left ventricular and right ventricular pacing time. Recently, the development of pacing technology leads separate pacing of LV and RV (optimal biventricular pacing), resulting in improvement of the incorrect EMR through sequential control of V-V prolonged duration, and amelioration of cardiac function. Quantitative analysis of left ventricular wall motion with tissue Doppler imaging (TDI) and evaluation of the synchronization the therapeutic effect of synchronized biventricular pacing have been reported abroad, and. application of optimalbiventricular pacing is illustrated recently. No study of optimal biventricular pacing is reported at home.Tissue Doppler technology such as tissue synchronization imaging (TSI), tissue velocity imaging (TVI), were applied to evaluate the immediate change and follow-up results of left ventricular systolic performance and synchronization of ultra-left ventricular wall motion between simultaneous biventricular pacing and optimal biventricular paciong.Materials and MethodsCases of candidate: (1) persistent congestive heart failure and no response to medicine therapy. (2) NYHA cardiac function grade III-IV. (3) LVEF ^35%. (4) LVEDd^60mm. (5) severe MR. (6) width of QRS 2^120ms. (7) informed consent. Ten cases were enrolled from March, 2004 and received implant of MEDTRONIC INSYNC III (type 8042) 3 chamber pacemaker. All the ten cases were suffered from dilated cardiomyopathy. All the candidates were examed with ECG, ECHO, 6 MHW 2 days prior to implant, 1 month, 3 months and 6 months after implant, and performed V-V optimize 1 week and 3 months after implant respectively. Record of all the ultrasonic values of biventriculay synchronized pacing (LV 4ms) and optimal V-V delay after optimal A-V interval. The left ventricular ejection fraction (LVEF), stroke volume (SV), aortic velocity time integral (VTI), left ventricular end diastolic diameter (LVEDd), the standard deviation of the electro-mechanical delay (EMD-SD) of 6 segments and TSI index were measured in every time when patient have ECHO examination. The mean value was calculated from 3 measurements.Results1. All the patients were implanted Medtronic Insync III (type 8042) 3 chamber pace maker and displayed excellent ultrasonic imaging. Among 10 cases, the initial optimal V-V interval was just synchronized pacing in 2 cases;some optimal V-V interval difference existed in other 8 cases, LV first pacing 20ms in 3 cases, RVfirst pacing 20ms in 2 cases and 3 cases of LV first pacing 12ms, 40ms,and 60ms respectively. All the cases performed optimal V-V again 3 months after implant;in comparison with the first optimize, the V-V interval was consistent. The NYHA heart function, 6 MHW, LVEDd, EF and SV were significantly improved in 6 months.2. After 6 month of implanting, the LVEF, SV and VTI were obviously increased from (22±8.8) % to (38 + 9.9) %;(36 + 14.9) ml to (57± 15.7) ml;(20.22 ±5.72) cm to (26.20+5.98) cm, P<0.05, respectively compared to the before of implanting. The LVEDd was decreased from (6.6 ± 0.6) cm to (6.0 + 0.9) cm P<0.05. The EMD-SD and TSI index were declined gradually after implanting, which was more evident in the 6 month after implanting, from (83.07±46.99) ms to (22.37± 16.38)ms;(2.20±0.36) to (1.50+0.43)PO.05 respectively.3. EMD-SD was no obvious change between simultaneous biventricular pacing andsequential biventricular pacing immediately, Whereas, the TSI index and VTI were significantly improved from( 1.87±0.31) to (1.71 ±0.29);(22.44±5.43)cm to (25.44±5.36)cm PO.05, respectively, in the sequential biventricular pacing.ConclusionSequential biventricular resynchronization could improve the left ventricular funcion and asynchronization in the patients with congestive heart failure, which is more effective than simultaneous biventricular pacing after implanting immediately.
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