| Background: It is well known that increased cumulative ventricular pacing (Cum VP% ) is one of the most important causes for adverse cardiovascular events, such as heart failure (HF), stroke and atrial fibrillation (AF). Therefore, reducing unnecessary ventricular pacing, preserving atrioventricualr synchronization and maintaining and promopting ventricular physiological activation have been a highlight in recent years.Objective: This study is to investigate the effects of different pacing modes on Cum VP%, synchrony and heat function in patients with pacemakers.Methods:①Pacemakers with managed ventricular pacing (MVP) algorithm were implanted in 42 patients including 41 with bradycardia and 1 with ventricular tachycardia. Conventional DDDR pacing, search atrioventricular conduction plus (SAV+) and MVP were performed for one month respectively. In each pacing algorithm the time percentages of four pacing and sense status including atrial sense-ventricular sense (AS-VS), atrial sense-ventricular pace (AS-VP) atrial pace-ventricular sense (AP-VS) and atrial pacing-ventricular pace (AP-VP) were obtained respectively. Cumulative atrial pacing proportion (Cum AP%) and Cum VP% were calculated in conventional DDDR pacing, SAV+ and MVP algorithm.②Percentages of patients’Cum VP% less than 40% were calculated in DDDR, Search AV+ and MVP algorithm.③Non-atrioventricular conduction block ( Group nAVB) and atrioventricular conduction block (Group AVB) were classified according to arrhythmic types. Group AVB was classfied as episodic III-degree AVB group (Group eIII°AVB) and permanent III-degree AVB group (Group pIII°AVB). Cum VP% was investigated respectively in DDDR, Search AV+ and MVP alogrithm.④When the effects of different pacing modes on ventricular synchrony were investigated, left ventricular synchrony in 36 cases with sick sinus syndrome (SSS) was evaluated by real-time three-dimensional echocardiology (RT-3DE) in AAIR, DDDR and VVIR algorithms.Parameters including global and 17-segmental volume-time curves (VTCs), dispersion of time to minimal regional volume for 16 left ventricular segments (Tmsv16-SD), dispersion of time to minimal regional volume for 12 left ventricular segments (Tmsv12-SD), dispersion of time to minimal regional volume for 6 left ventricular segments (Tmsv6-SD), and maximal difference of time to minimal regional volume for l6 left ventricular segments (Tmsv16-Dif), maximal difference of time to minimal regional volume for l2 left ventricular segments (Tmsv12-Dif), maximal difference of time to minimal regional volume for 6 left ventricular segments (Tmsv6-Dif).⑤When the effects of different pacing modes on heart function were studied, bedside B-type natriuretic peptide (BNP) was assayed in 36 cases with SSS in AAIR, DDDR and VVIR mode.Results:①In DDDR algorithm AS-VS , AS-VP, AP-VS and AP-VP were 2.4%, 52.3%, 2.5% and 42.8% respectively. In SAV+ algorithm were 19.3%,34.9%, 33.8% and 12.0% respectively. In MVP were 38.9%, 13.2%, 41.5% and 6.4% respectively. Cum VP% were 95.1%, 46.9% and 19.6% respectively (P<0.05) in three algorithms above.②The percentages of Cum VP% <40% were 0, 23.8% and 95.2% respectively in DDDR, Search AV+ and MVP algorithm (P<0.05).③Cum VP% were different in DDDR, Search AV+ and MVP algorithm in patients with different arrhythmias. Cum VP% were 94.9%, 52.2% and 1.6% respectively in DDDR, Search AV+ and MVP algorithm in Group nAVB (P<0.05). Cum VP% were 94.2%, 40.2% and 17.5% respectively in DDDR, Search AV+ and MVP algorithm in Group eIII°AVB (P<0.05). Cum VP% were 99.5%, 98.1% and 97.8% respectively in DDDR, Search AV+ and MVP algorithm in Group pIII°AVB (P>0.05).④The volume-time curves (VTCs) were applied in this study to reflect left ventricular synchronicity in 36 cases with SSS in AAIR, DDDR and VVIR. The 17 segments of VTCs were arranged regularly and were almost the same time to maximum and minimum systolic volume, and had a symmetry in early systolic and early diastolic phases in AAIR mode, synchronization was better;In DDDR mode, some segments of VTCs arranged in confusion, inconsistency ups and downs, had a bad symmetry in early systolic and early diastolic phases, synchronization is poor; And in VVIR mode, 17 segments of VTCs were apparent confusion, they reached maximum volume and minimum volume at different times, had the worst synchronization. The parameters reflecting left ventricular systolic synchronicity, i.e., Tmsv16-SD, Tmsv12-SD, Tmsv6-SD, Tmsv16-Dif, Tmsv12-Dif, and Tmsv6-Dif were 11.73±2.94ms, 11.27±3.24ms, 11.07±2.74ms, 28.27±7.81ms, 26.27±8.18ms, 18.60±5.82 ms in AAIR mode, and in DDDR mode, they were 31.67±9.02 ms, 22.60±5.72 ms, 17.20±4.51 ms, 95.53±36.02 ms, 62.07±23.89 ms, 31.67±11.95 ms, and 31.67±9.02 ms, 22.60±5.72 ms, 17.20±4.51 ms, 95.53±36.02 ms, 62.07±23.89 ms, 31.67±11.95 ms in VVIR mode. The parameters were significantly lower in AAIR than those in DDDR and VVIR (P<0.05), and had no difference between DDDR and VVIR (P>0.05).⑤BNP level in AAIR was 148±11pg/ml after pacing for one month. Compared with BNP in 150±12 pg/ml prior to procedure, there was no significant difference (P>0.05). BNP was 197±20 pg/ml in DDDR pacing for one month. Compared with BNP levels in pre-procedure and AAIR pacing, BNP was higher and there was statistically significance (P<0.05). BNP was 210±21 pg/ml in VVI pacing for one month. Compared with BNP level in DDDR pacing for one month, there was no statistically implication (P>0.05); however, there was remarkably significance in comparision with BNP levels in pre-operation and AAIR pacing (P<0.05).Conclusion: Compared with conventional DDDR Both the MVP and SAV+ algorithms significantly reduce the Cum VP%, especially MVP algorithm. MVP is dynamic AAIR pacing mode. Compared with DDDR and VVIR, MVP and AAIR can maintain patients’cardiac synchrony; reduce blood BNP level and protect heart function. |
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