中文摘要（关键词）

第一部分 定量的影像距离和心电图指标指导导线植入位点的选择以提高左束支起搏成功率

背景：左束支起搏（left bundle branch pacing, LBBP）是一种新的接近生理性的起搏方式，近年来受到广泛的关注和应用。然而，在导线植入位点选择方面，不同于希氏束起搏可以直接标测到希氏束电位作为植入靶点，LBBP尚未有统一的定量标准作为参考。

目的：本研究旨在定量地分析LBBP植入成功概率和导线植入位点分布、导线定位起搏心电图（electrocardiogram, ECG）参数之间的关系，从而明确成功实现LBBP的规律，并总结出定量的标准指导LBBP植入位点的选择。

方法：连续纳入成功植入LBBP的患者，将患者术中记录完整的尝试位点纳入分析，包括成功位点和失败位点。发明一种新的坐标系统，将导线植入位点的分布定量描述为纵向距离（longitudinal distance, longit-dist）和横向距离（lateral distance, lat-dist）。为了排除心脏大小个体间差异的影响，提出并计算了校正的longit-dist和校正的lat-dist。测量每个位点定位起搏（localization pacing）时的ECG参数，包括起搏QRS时长（locat-QRSd）、左室激动时间（locat-LVAT）、locat-LVAT和locat-QRSd的比值（locat-LVAT/QRSd）以及肢体导联QRS波方向。

结果：共纳入94例患者，其中包括105个成功位点，93个失败位点。相比于失败位点，成功位点的longit-dist、校正的longit-dist显著更长，而locat-QRSd、locat-LVAT、locat-LVAT/QRSd显著更短。进一步分析得出LBBP植入成功概率和校正的longit-dist成正剂量-反应关系，界值为26.95mm；而与locat-QRSd、locat-LVAT以及locat-LVAT/QRSd呈负剂量-反应关系，界值分别为142ms、92ms、64.7%。另外，II/III导联QRS波呈负向或负向为主也和成功LBBP相关。

结论：longit-dist、locat-QRSd、locat-LVAT和locat-LVAT/QRSd是能指导LBBP导线植入位点选择的定量指标。

第二部分 影响左束支起搏阳极环夺获成功率和QRS波时长缩短程度的因素分析

背景：左束支起搏（left bundle branch pacing, LBBP）是一种接近生理性的起搏方式，能维持左心室内同步性，但仍会导致右室传导延迟（right ventricular conduction delay, RVCD），影响双室同步性。然而，LBBP双极起搏时阳极环夺获（anodal-ring capture, ARC）的现象被发现，有研究报道称ARC有提高双室同步性的潜力，但目前对于LBBP-ARC的认识仍十分有限。

目的：本研究旨在综合地分析影响LBBP-ARC成功实现和QRS波时长（QRS duration, QRSd）缩短程度的因素，加深对LBBP-ARC机制的认识，并为导线植入提供参考。

方法：连续纳入成功植入LBBP并且术中进行ARC测试的患者。测量患者起搏心电图参数，包括刺激信号起始的QRS时长（stimulus-to-QRS duration, stim-QRSd）、左/右室激动时间（stimulus-to-left/right ventricular activation time, stim-LVAT/RVAT）以及右-左室激动时间（RV-LVAT）间隔。应用第一部分中提出的坐标系统，将导线植入位点的分布定量描述为校正的纵向距离（longitudinal distance, longit-dist）和校正的横向距离（lateral distance, lat-dist）。研究应用了组间比较、相关性分析和逐步Logistic回归等分析方法。

结果：共纳入105例成功植入LBBP并具有完整术中心电图和影像资料的患者，其中65例（62%）在起搏输出≤5.0V/0.5ms下成功实现ARC（平均ARC阈值3.1V/0.5ms）。ARC在LBBP的基础上能进一步缩短stim-QRSd（∆stim-QRSd = -13.1±7.5 ms, P < 0.0001）。LBBP-ARC组中更好的单极环阈值和R波感知提示良好的“环-间隔”接触在成功ARC中的关键作用。更长的校正longit-dist和更短的校正lat-dist与成功ARC独立相关，可能由于导线进入间隔时更大的相对角度，导致更长的导线间隔内长度以及相应更好的“环-间隔”接触。另外，更短的stim-LVAT和更长的stim-QRSd都与ARC后更大的QRSd缩短程度相关，但事实上，这与更长的RV-LVAT间隔相关。

结论：该研究进一步描述了LBBP-ARC的心电图和影像特征，发现了影响成功ARC和ARC后QRSd缩短程度的影响因素。更靠近前中间隔的区域实现LBBP-ARC的概率更高。ARC能进一步缩短QRSd，尤其是在LBBP时室间电不同步性更大的患者中。

第三部分 使用Solia S60导线+Selectra 3D鞘实现左束支区域起搏的可行性研究（对比3830导线+C315 HIS鞘）

背景：随着左束支区域起搏（left bundle branch area pacing, LBBAP）的推广应用，导线和植入工具仍需要进一步发展，以提供更多的选择、丰富使用场景并防止行业垄断。目前广泛使用的是美国美敦力公司生产的3830导线和C315系列鞘管，该器械的可靠性和安全性已被证明，并已积累了许多使用经验。后来德国百多力公司生产的Solia S系列导线和Selectra 3D鞘管也可用于LBBAP，但仍处于初期应用阶段，关于该器械的手术效果和使用经验还非常有限。

目的：作为国内使用Solia S导线和Selectra 3D鞘最初的试用经验，本研究旨在描述该器械手术特征、起搏效果和影像特点，并与3830导线进行对比，分析两者的差别。

方法：连续纳入使用Solia S60导线和Selectra 3D鞘管进行LBBAP植入的患者，以及同期使用3830导线和C315 HIS鞘进行左束支区域起搏的患者，识别成功实现LBBAP患者并计算成功率。使用倾向性匹配的方法匹配出与Solia S60组患者基线临床特征相近的3830组患者作为对照组，以进行进一步的手术特征、起搏效果和影像的比较。收集患者术中出现的并发症，包括室间隔穿孔、间隔血管损伤、导线脱位、气胸、血胸和心脏穿孔等。

结果：在纳入时间区间内，分别有27例患者使用Solia S60导线和78例患者使用3830导线进行LBBAP植入，成功实现LBBAP的患者分别为22例和67例，成功率分别为81.5%和85.9%，没有显著差异。倾向性匹配获得35例使用3830导线成功实现LBBAP的患者作为对照组，基线特征与Solia S60组相近。比较得到在位点成功率、单次成功比例、左束支电位记录比例、左束支夺获情况、LBBAP导线植入用时及放射时间、起搏参数、起搏QRS时长和左室激动时间、导线植入位点分布等方面没有显著差异。在并发症方面，两种器械的并发症均处于较低水平，Solia S60组出现1例因头端螺旋回退导致导线脱位和1例损伤冠状静脉，需要引起临床的关注。

结论：Solia S60导线配合Selectra 3D鞘管用于LBBAP具有可行性，能获得和3830导线配合C315 HIS鞘管相近的成功率和起搏效果。但其是否增加血管损伤的风险仍需进一步研究。

Abstract (Keywords)

Part I Quantitative Distance and Electrocardiographic Parameters for Lead-implanted Site Selection to Enhance the Success likehood of Left Bundle Branch Pacing

Background: Left bundle branch pacing (LBBP) is a novel near-physiological pacing method that still lacks quantitative criteria to guide the selection of lead-implanted sites to enhance the success likelihood of lead deployments.

Ojective: This study aimed to quantitatively analyze the relationships of LBBP success likelihood to the distribution of lead-implanted sites and the lead-localization-pacing electrocardiographic (ECG) features.

Methods: All the lead-implanted sites in patients with finally successful LBBP were enrolled for analysis, including successful and failed sites. A novel coordinate system was invented to describe the sites’ distribution as longitudinal distance (longit-dist) and lateral distance (lat-dist). Corrected distance parameters were generated to eliminate the cardiac dimension variations. The lead-localization-pacing ECG parameters were also collected, such as paced QRS duration (locat-QRSd), left ventricular activation time (locat-LVAT), LVAT/QRSd ratio (locat-LVAT/QRSd), and QRS directions.

Results：A total of 94 patients with 105 successful sites and 93 failed sites were enrolled. Longit-dist and corrected longit-dist of successful sites were significantly longer, while locat-QRSd and locat-LVAT were shorter and locat-LVAT/QRSd was lower than failed sites. There was a positive dose-response relationship between LBBP success likelihood and corrected longit-dist with a cut-off of 26.95mm, whereas there were negative dose-response relationships of LBBP success likelihood to locat-QRSd, locat-LVAT, and locat-LVAT/QRSd with the cut-offs of 142ms, 92ms, and 64.7%, respectively. Downward QRS direction in II/III ECG leads was also associated with successful LBBP.

Conclusions: Longit-dist, locat-QRSd, locat-LVAT, and locat-LVAT/QRSd were quantitative parameters to guide the selection of lead-implanted sites during LBBP implantation.

Part II Pacing Features and Factors Influencing Success Likelihood and QRS Shortening in Bilateral Bundle Branch Area Pacing

Background: Left bundle branch pacing (LBBP) maintains left ventricular synchrony but induces right ventricular conduction delay (RVCD). Anodal-ring capture (ARC) was observed to improve RVCD, but the understanding of this phenomenon is limited.

Objective: This study aimed to analyze the electrical features and influencing factors of ARC in LBBP.

Methods: Patients receiving LBBP with intraoperative ARC testing were retrospectively enrolled. Electrocardiographic (ECG) parameters, like stimulus-to-QRS duration (stim-QRSd), stimulus-to-left/right ventricular activation time (stim-LVAT/RVAT), and RV-LVAT interval, were measured. A novel coordinate system was applied to describe the lead-implanted sites, including the corrected longitudinal (longit-dist) and corrected lateral distance (lat-dist). Intergroup comparisons, correlation analysis, and stepwise logistic regression were performed.

Results: Totally 105 patients with ECG and fluoroscopic data were included, among which 65 (62%) patients achieved ARC at a pacing output ≤ 5.0 V/0.5ms (average 3.1 V/0.5ms). ARC further shortened the stim-QRSd (∆stim-QRSd = -13.1 ± 7.5 ms, P < 0.0001) on the basis of LBBP. Better unipolar-ring threshold and R-wave sensing in LBBP-ARC group indicating the critical role of ring-septum contact in ARC. Longer corrected longit-dist and shorter corrected lat-dist were positively correlated with the success likelihood of ARC, likely due to the greater relative angle of lead while entering the septum, which leads to the greater intra-septal lead length and better ring-septum contact. Shorter stim-LVAT and longer stim-QRSd during LBBP correlated with greater QRS shortening after ARC, which actually depended on the prolonged RV-LVAT interval.

Conclusions: This study identified an area closer to the anterior-middle septum with higher success likelihood of ARC in LBBP. ARC could further shorten QRSd especially in patients with greater interventricular electrical dyssynchrony during LBBP.

Part III Comparison Between Solia S60 Lead+Selectra 3D Sheath and 3830 Lead+C315 His Sheath in Achieving Left Bundle Branch Area Pacing

Background: To promote wider adoption and avoid monopolies, more options for left bundle branch area pacing (LBBAP) are needed. Medtronic Inc.'s 3830 lead and C315 sheaths are currently the most commonly used and have been proven safe and effective. Biotronik Inc. has also developed their own LBBAP instruments, like Solia S leads and Selectra 3D sheaths, but they are still in the early stages with limited experience.

Aim: This study aimed to compare the procedure characteristics, pacing performance, and lead-implanted site distribution between these two instruments.

Methods: Patients received LBBAP implantation by Solia S60 lead and Selectra 3D sheath were consecutively enrolled, as well as patients using 3830 lead and C315 HIS sheath in the same period. Patients with successful procedures were identified and the success rate was calculated. The propensity score matching (PSM) was used to select comparable patients with 3830 lead as the control group. Then, procedure characteristics, pacing performance, and imaging features were compared. Complications were documented, such as pneumothorax, hemothorax, cardiac perforation, ventricular septal perforation, septal vascular injury, and lead dislodgement.

Results: Totally 27 and 78 patients received LBBAP implantation with Solia S60 lead and 3830 lead in the enrollment period, among which 22 (81.5%) and 67 (85.9%) patients successfully achieved LBBAP, respectively. The success rates had no significant difference. No significant differences were found between two groups in site success rate, proportion of one-time success, LBB potential record, LBB capture, time consumption of LBBAP lead implantation, radiation time, pacing parameters, paced QRS duration, left ventricular activation time, and distribution of lead-implanted sites. The incidences of complications were low in both groups, but two patients occurred lead dislodgement due to helix rollback and coronary vein injury in Solia group, requiring clinical concern.

Conclusions: Solia S60 lead with Selectra 3D sheath is feasible in achieving LBBAP. It had a similar success rate and pacing performance to 3830 lead and C315 HIS sheath. However, further study is required to analyze the risk of vascular injury.