Mid-septal Pacing Research Articles

His and para-His pacing in AV block: feasibility and electrocardiographic findings

Right ventricular apical pacing induces a dyssynchronous activation of the left ventricle and is associated with adverse clinical outcome. We aimed to establish permanent His-bundle pacing or para-His pacing in patients with high-grade atrioventricular (AV) block. We included patients with pacemaker indication due to second- or third-degree AV block, left ventricular ejection fraction >0.40, QRS duration <120ms, and sinus rhythm. All patients received a pacemaker with one atrial lead, one right ventricular mid-septal lead, and one lead in the His bundle or in the para-His position. Pacing from apex was performed temporarily. Patients were followed for 12months. Thirty-eight patients were included (mean age, 67 ± 10years; 30 (79%) male). Mean implantation time was 85 ± 31min, mean fluoroscopy time was 23 ± 13min, and mean position attempts of the His bundle lead was 8 ± 5. In four patients, we established direct His-bundle pacing with a mean QRS of 100 ± 19ms, and in 28 patients, para-His pacing was achieved with a mean QRS of 112 ± 18ms, and in six patients, neither direct His-bundle pacing or para-His pacing could be achieved. The mean QRS duration was 153 ± 12ms with mid-septal pacing and 161 ± 15ms with apical pacing. Stable direct His-bundle pacing or para-His pacing is feasible in 85% of patients with narrow QRS and high-grade AV block and leads to a normal or near-normal ventricular activation pattern.

Effect on Cardiac Function of the Right Ventricular Mid-Septal Pacing Procedure with Narrow QRS Complexes in Patients with Permanent Pacemaker Implantation

Introduction: In pacemaker implantation, ventricular pacing leads were conventionally positioned on the right ventricular apex (RVA). However, this procedure causes some deleterious effects. It has been reported that an alternative procedure i.e., the right ventricular mid-septal (RVMS) pacing makes a narrow QRS complexes. In this study, we compared cardiac function between the RVA pacing and the RVMS pacing with one-year follow-up. Methods: We enrolled 136 RVMS-pacing patients (76±11 years) who underwent a permanent pacemaker implantation suffering from bradyarrhythmias. Pacemaker indices, a paced QRS duration, and brain natriuetic peptide (BNP) were measured one-year after implantation. These data were compared to 60 RVA-pacing patients. Results: Pacemaker indices did not differ between the RVMS-pacing and the RVA-pacing. A paced QRS duration in the RVMS-pacing was shorter than that of the RVA-pacing (124±17 vs. 148±11 ms, P<0.01). BNP levels one-year after implantation were not increased in the RVMS-pacing, whereas it was increased in the RVA-pacing (9% vs. 22%, P<0.01). Conclusion: This prospective observational study reveals that an alternative RVMS-pacing procedure contributes to less conduction delay and cardiac dysfunction compared with a conventional RVA pacing procedure in patients with permanent pacemaker implantation.

Utility of the surface electrocardiogram for confirming right ventricular septal pacing: validation using electroanatomical mapping

When targeting the interventricular septum during pacemaker implantation, the lead may inadvertently be positioned on the anterior wall due to imprecise fluoroscopic landmarks. Surface electrocardiogram (ECG) criteria of the paced QRS complex (e.g. negativity in lead I) have been proposed to confirm a septal position, but these criteria have not been properly validated. Our aim was to investigate whether the paced QRS complex may be used to confirm septal lead position. Anatomical reconstruction of the right ventricle was performed using a NavX® system in 31 patients (70 ± 11 years, 26 males) to validate pacing sites. Surface 12-lead ECGs were analysed by digital callipers and compared while pacing from a para-Hissian position, from the mid-septum, and from the anterior free wall. Duration of the QRS complex was not significantly shorter when pacing from the mid-septum compared with the other sites. QRS axis was significantly less vertical during mid-septal pacing (18 ± 51°) compared with para-Hissian (38 ± 37°, P = 0.028) and anterior (53 ± 55°, P = 0.003) pacing, and QRS transition was intermediate (4.8 ± 1.3 vs. 3.8 ± 1.3, P < 0.001, and vs. 5.4 ± 0.9, P = 0.045, respectively), although no cut-offs could reliably distinguish sites. A negative QRS or the presence of a q-wave in lead I tended to be more frequent with anterior than with mid-septal pacing (9/31 vs. 3/31, P = 0.2 and 8/31 vs. 1/31, P = 1.0, respectively). No single ECG criterion could reliably distinguish pacing the mid-septum from the anterior wall. In particular, a negative QRS complex in lead I is an inaccurate criterion for validating septal pacing.

Abstract 2163: Single-site Left Ventricular Apex And Left Ventricular Septal Pacing For Long Term Maintenance Of Cardiac Contractility

Objective: Conventional right ventricular (RV) apex pacing is associated with asynchronous activation and reduced left ventricular (LV) pump function. Previous studies have shown acute hemodynamic benefits over RV apex pacing by LV septal or LV apex pacing. We investigated whether this improvement translates into a long-term benefit and how acute LV function during single site LV pacing compares to biventricular pacing. Methods: After AV-nodal ablation, mongrel dogs were randomized to receive 16 weeks of VDD pacing at the RV apex (n = 7), LV apex (n = 7), or LV mid-septum (n = 8; trans-ventricular septal approach). LV contractility (dP/dt max /P instantaneous ) was measured during normal ventricular conduction from atrial pacing (AP) and during ventricular pacing 1–3 hours and 16 weeks after implant. At 16 weeks, contractility was also measured after an acute switch from the implant site (IS) to the non-implanted apex (both for LV septal group) and to RV apex + LV lateral (BiV) pacing. Results: While acute and chronic RV apex pacing significantly reduced contractility (Figure a ; mean ± SD, *p&lt;0.05 contrasted to 1), LV pacing maintained contractility near AP levels. After 16 weeks of RV apex pacing, switching to LV apex pacing (but not BiV pacing) increased contractility (Figure b ). After 16 weeks of LV pacing, switching to RV apex pacing decreased contractility. Collectively, acute LV apex pacing enhanced contractility over acute BiV (p&lt;.001). Conclusions: Chronic LV apex and LV mid-septal pacing maintain contractility near normal levels, and at a higher level than RV apex pacing. Acutely, LV apex pacing improves contractility compared to BiV pacing.

Selective site pacing: Rationale and practical application

Although it has become traditional to place permanent pacemaker leads at the right ventricular apex and right atrial appendage, pacing from these locations poorly mimics normal physiology. A growing evidence base shows that right ventricular apical pacing results in ventricular dyssynchrony and various adverse effects. Provocative data from early trials suggest that pacing from alternate sites in the right ventricle--His bundle pacing, para-Hisian pacing, septal right ventricular outflow tract pacing, and right ventricular midseptal pacing--may lead to improved results. Similarly, early data suggest that right atrial pacing near Bachmann's bundle may lead to superior outcomes when compared with pacing from the right atrial appendage. Several large-scale, randomized clinical trials are now under way to establish the future role of selective site pacing.

Anatomic and Electrophysiologic Differences between Chronic and Paroxysmal Atrial Flutter: Intracardiac Echocardiographic Analysis

It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia. The aim of the study was to compare intracardiac echocardiographic (ICE) images of the crista terminalis (CT) and transverse conduction properties of the CT between chronic and paroxysmal forms of common AFL. Chronic AFL (n = 7) was defined as non-self-terminating AFL lasting >1 month, and paroxysmal AFL (n = 8) was defined as an intermittent arrhythmia with symptomatic episodes of 24 hours maximum duration. ICE images of the right atrium were recorded with a 9 F 9-MHz intracardiac ultrasound catheter during pullback at 0.5-mm intervals from the superior vena cava to the inferior vena cava triggered by electrocardiogram and respiration. The two-dimensional image of the right atrium was reconstructed into a three-dimensional (3-D) image. Three-dimensional images from patients with chronic AFL showed the CT to be thick and continuous, and conduction across the CT was blocked at a pacing rate just above sinus rhythm in all seven patients. In contrast, 3D images from paroxysmal AFL showed the CT to be thin and discontinuous, and conduction across the CT during midseptal pacing was observed in five of the eight patients. The nature of AFL is determined, at least in part, by anatomic and electrophysiologic characteristics of the CT.