Devices
New Approach Concept of Leadless Pacemaker Implantation for Smaller Hearts
2024 Volume 88 Issue 7 Pages 1135-1137
Details
2024 Volume 88 Issue 7 Pages 1135-1137
The main use of leadless pacemakers has been for patients with bradycardic atrial fibrillation and older patients, but recently they are being considered for use in younger patients who are at higher risk of infection, have a history of infection, or have endstage renal failure which vessel sparing is desired.1 The utility of these pacemakers is high and the Micra CED study reported that they have a similar all-cause mortality rate and significantly lower rates of remote complications, device re-intervention, infection, and heart failure hospitalization as transvenous pacemakers.2 Furthermore, leadless pacemakers have been reported to reduce overall complications by 48%.3 Although the frequency of acute complications internationally and in Japan is low at 3–4%,4,5 cardiac perforation and pericardial effusion occur in 1–2%,4–6 and these complications can be severe. In addition, real-world data from the USA are 16% for acute complications and 5% acute deaths,7 and acute events are potentially fatal. Thus, although the current implantation of leadless pacemakers is safe and has shown good results, there are still concerns about problems during implantation.
Article p 1127
The mean operative time in Japan is reported to be longer than in international studies, which may be due to the smaller anatomy of Japanese patients.8 In fact, differences related to the smaller body size of Asians have been reported in other device surgeries.9 The current standard technique for leadless pacemaker implantation is the femoral approach, which can result in a tortuous path in smaller anatomies. Leadless pacemaker implantation in children is the best example, and there are reports of difficulties in approach that were solved by using a trans-jugular route.10,11 Another study in 82 patients reported that leadless pacemakers were safely implanted using the jugular approach.12 Furthermore, the jugular approach can also be considered in cases of obstruction of the inferior vena cava (IVC) or severe stenosis (vein thrombosis etc.).13 Thus, the jugular approach may be an alternate method to the standard femoral approach for smaller anatomies, but there is no evidence to prove why it is useful.
In this issue of the Journal, Soejima et al14 examine whether the jugular approach is appropriate by evaluating the size of the jugular vein based on data extracted from PubMed, and they also examine the reasons for the usefulness of the jugular approach by selectively extracting “typical hearts” of typical size worldwide and “smaller hearts” typical of Asian people including Japanese and actually comparing them on images. Based on their evaluations, Soejima et al present 3 noteworthy results (Figure).
The 3 important clinical implications in this study proved by Soejima et al.14 Image reproduced with permission of Medtronic. IVC, inferior vena cava; SVC, superior vena cava; TV, tricuspid valve.
First, the diameter of the jugular vein was evaluated to ensure that the introducer sheath of the Micra leadless pacemaker (27Fr, 9 mm; Figure) could be safely inserted into the vessel. The mean diameter of the right jugular vein confirmed by the Valsalva maneuver was larger than the outer diameter of the introducer sheath regardless of age, suggesting that the sheath could be safely implanted. In fact, there are reports of safe implantation even in pediatric cases.10,11 On the other hand, there were no data for the left jugular vein in older patients, and the mean vessel diameter confirmed by the Valsalva procedure in younger patients was similar to the diameter of the introducer sheath, indicating that routine use of the left jugular vein is not justified. There is a report of leadless pacemaker implantation via the left jugular vein in a 7-year-old child,15 and although the approach seems feasible in practice, prior vascular diameter evaluation by some imaging test is essential.
Second, freedom within the right atrium seems important for an easy approach to the right ventricle, and was evaluated with respect to the delivery tool and the size of the right atrium. Regardless of femoral or jugular approach, the probability that the delivery tool was larger than the distance from the approach site (superior vena cava [SVC] and IVC) to the tricuspid valve (TV) was higher in the smaller heart. This finding implies difficulty with smaller heart surgery and may be one reason for the longer operative time in the Japanese population.
Third, the angle and distance of approach to the TV from the IVC and SVC, respectively, were examined. The SVC approach provided a 38–40% gentler angle to the TV regardless of heart size compared with the IVC approach. Although it may be difficult to isolate 1 parameter for evaluation, because of the influence of various parameters, the results suggest that the SVC may be an easier approach in patients who present difficulty with the femoral approach.
Thus, the report by Soejima et al is excellent because it presents results that are meaningful for clinical practice on topics for which evidence has been lacking (i.e., the clinical usefulness of the jugular approach and the difficulty of performing surgery in smaller anatomies). (1) Using the right jugular approach for placement of the introducer sheath is safe (whereas the left jugular vein needs individual evaluation by imaging examination); (2) the current Micra system is too large for smaller hearts; and (3) the jugular vein approach may overcome difficulties with the femoral vein approach.
This study is expected to play a very important role in future implantation techniques for leadless pacemakers, and it is hoped the accumulation of actual clinical data on the efficacy and safety of the jugular approach.
The authors used DeepL Translate for translation.
K.I. received honoraria for lectures from Medtronic Japan Co., Ltd., JAPAN LIFELINE Co., Ltd., and Biotronik Japan Inc. K.K. received honoraria for lectures and research grants from Medtronic Japan Co., Ltd.
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