Delivery catheter system carries more physiological right ventricular septal pacing than stylet system

INTRODUCTION

The Mt. FUJI multicenter trial demonstrated that a delivery catheter system had a higher rate of successful right ventricular (RV) lead deployment on the RV septum (RVS) than a conventional stylet system. In this subanalysis of the Mt. FUJI trial, we assessed the differences in electrocardiogram (ECG) parameters during RV pacing between a delivery catheter system and a stylet system and their associations with the lead tip positions.

METHODS

Among 70 patients enrolled in the Mt FUJI trial, ECG parameters, RV lead tip positions, and lead depth inside the septum assessed by computed tomography were compared between the catheter group (n = 36) and stylet group (n = 34).

RESULTS

The paced QRS duration (QRS-d), corrected paced QT (QTc), and JT interval (JTc) were significantly shorter in the catheter group than in the stylet group (QRS-d: 130 ± 19 vs. 142 ± 15 ms, p = .004; QTc: 476 ± 25 vs. 514 ± 20 ms, p < .001; JTc: 347 ± 24 vs. 372 ± 17 ms, p < .001). This superiority of the catheter group was maintained in a subgroup analysis of patients with an RV lead tip position at the septum. The lead depth inside the septum was greater in the catheter group than in the stylet group, and there was a significant negative correlation between the paced QRS-d and the lead depth.

CONCLUSION

Using a delivery catheter system carries more physiological depolarization and repolarization during RVS pacing and deeper screw penetration in the septum in comparison to conventional stylet system. The lead depth could have a more impact on the ECG parameters rather than the type of pacing lead.

Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site

BACKGROUND

The prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12‑lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated. However, in this study, this relationship was analyzed quantitatively, and accurate evaluation of the pacing site was determined using computed tomography (CT).

METHODS

Of 779 consecutive outpatients, 65 who underwent pacemaker implantation and thoracic CT were prospectively included and classified into the following groups according to the lead tip position: free-wall, septal, or septum/free-wall boundary (hinge) group. The hinge was used as an anatomical marker, and the distance from the hinge to the lead tip was measured. Under RV pacing, a 12‑lead ECG was obtained. ECG findings were evaluated using three criteria (including lead I, II, and aV_L and precordial leads V₅ and V₆) previously reported to be useful in differentiating pacing sites.

RESULTS

The lead tips were anchored at the free-wall in 10 patients, the septal wall in 19 patients, and the hinge in 32 patients. Paced QRS duration correlated with the distance from the hinge to the lead tip for the free-wall and septum (r = 0.47 and - 0.68, respectively). Estimation of the lead tip implantation site using the ECG algorithm was useful; however, the algorithm's accuracy decreased around the hinge.

CONCLUSIONS

ECG is useful in differentiating pacing sites but is less accurate around the hinge, which may be the reason that the identification of the RV pacing site using ECG remains controversial.

Effects of long-term right ventricular apex pacing on left ventricular dyssynchrony, morphology and systolic function

BACKGROUND

Right ventricular apex (RVA) is still the most common implanted site in the world. There are a large number of RVA pacing population who have been carrying dual-chamber permanent pacemaker (PPM) over decades. Comparison of left ventricular dyssynchrony, morphology and systolic function between RVA pacing population and healthy population is unknown.

METHOD

This case-control study enrolled 61 patients suffered from complete atrioventricular block (III°AVB) for replacement of dual-chamber PPM. Then, 61 healthy controls matched with PPM patients in gender, age, follow-up duration and complications were included. The lead impedance, pacing threshold and sensing were compared between at implantation and long-term follow-up. Left ventricular (LV) dyssynchrony, morphology and systolic function were compared between RVA pacing population (RVA group) and healthy population (healthy group) at implantation (baseline) and follow-up. And clarify the predictors of LV systolic function in RVA group at follow-up.

RESULTS

After 112.44 ± 34.94 months of follow-up, comparing with parameters at implantation, atrial lead impedance decreased significantly (690 ± 2397 Ω vs 613 ± 2257 Ω， p = 0.048); atrial pacing threshold has a increased trend and P-wave amplitude has a decreased trend, but there was no statistical differences; while, RVA ventricular lead threshold increased significantly (0.50 ± 0.23 V vs 0.91 ± 0.47 V， p < 0.001), impedance (902 ± 397 Ω vs 680 ± 257 Ω，p < 0.001) and R-wave amplitude (11.71 ± 9.40mv vs 7.00 ± 6.91 mv， p < 0.001) decreased significantly. Compared with healthy group, long-term RVA pacing significantly increased ventricular dyssynchrony (mean QRS duration, 156.21 ± 29.80 ms vs 97.08 ± 15.70 ms， p < 0.001), left atrium diameter (LAD, 40.61 ± 6.15 mm vs 37.49 ± 4.80 mm，p = 0.002), left ventricular end-diastolic diameter (LVEDD, 49.15 ± 5.93 mm vs 46.41 ± 3.80 mm，p = 0.003), left ventricular hypertrophy (LVMI, 121.86 ± 41.52 g/m2 vs 98.41 ± 25.29 g/m2，p < 0.001), significantly deteriorated degree of tricuspid regurgitation (p < 0.001), and significantly decreased left ventricular ejection fraction (LVEF, 61.38 ± 8.10% vs 64.64 ± 5.85%, p = 0.012), but after long-term RVA pacing, the mean LVEF was still more than 50%. Long-term RVA group LVEF was negatively correlated with preimplantation LVMI (B = -0.055，t = -2.244，p = 0.029), LVMI at follow-up (B = -0.081，t = -3.864，p = 0.000) and tricuspid regurgitation at follow-up (B = -3.797，t = -3.599，p = 0.001).

CONCLUSION

In conclusion, although long-term RVA pacing has significantly effects on left ventricular dyssynchrony, morphology and systolic function in III°AVB patients, the mean LVEF is still >50%. High preimplantation LVMI can predict the decline of LVEF.

Clinical Influence and Predictors of Pacing-Induced Mechanical Asynchrony in Patients with Normal Cardiac Function with Ventricular Lead Placed in Non-Apical Position

Right ventricular apical (RVA) pacing often causes left ventricular (LV) mechanical asynchrony, which is enhanced by impaired cardiac contraction and intrinsic conduction abnormality. However, data on patients with normal cardiac function and under RV non-apical (non-RVA) pacing are limited.We retrospectively investigated 97 consecutive patients with normal ejection fraction who received pacemaker implantation for atrioventricular block with the ventricular lead placed in a non-RVA position. We defined mechanical asynchrony as discoordinate contraction between opposing regions of the LV wall evaluated by echocardiography. Asynchrony was detected in 9 (9%) patients at baseline and in 38 (39%) under non-RVA pacing (P < 0.001). Asynchrony at baseline was significantly associated with complete left bundle branch block (CLBBB) [odds ratio (OR) = 20.8, P < 0.001]. Asynchrony under non-RVA pacing was significantly associated with left anterior fascicular block (LAFB) (OR = 7.14, P < 0.001) and CLBBB (OR = 13.3, P = 0.002) at baseline. New occurrence of asynchrony was significantly associated with LAFB at baseline (OR = 5.88, P = 0.001). During a median follow-up period of 4.8 years, the incidence of device-detected atrial fibrillation (AF) was more frequent in patients who developed asynchrony than in those who did not (53.3% versus 27.5%, hazard ratio = 2.17, 95% confidence interval = 1.02-4.61, P = 0.03).In patients with normal cardiac function, LAFB at baseline was significantly associated with new occurrence of mechanical asynchrony under non-RVA pacing. Abnormal contraction had a significant influence on the incidence of device-detected AF.

Effects of right ventricular septum or His-bundle pacing versus right ventricular apical pacing on cardiac function: A systematic review and meta-analysis of randomized controlled trials

Objective

Recent studies have demonstrated that right ventricular apical (RVA) pacing has a deleterious impact on left ventricular function, while right ventricular septum (RVS) or His-bundle pacing (HBP) contribute to improvements in cardiac function. A meta-analysis of randomized controlled trials (RCTs) was conducted to compare the mid- and long-term effects of RVS and HB pacing versus RVA pacing on cardiac function.

Methods

Eligible RCTs were identified by systematically searching the electronic literature databases PubMed®, Cochrane Library, Embase® and Ovid®.

Results

Seventeen articles (n = 1290 patients) were included in this meta-analysis, including 14 studies comparing the effects of RVA and RVS pacing on cardiac function and three studies comparing HBP with pacing at other sites. Compared with RVA pacing, RVS or HBP exhibited a higher left ventricular ejection fraction (LVEF) (weighted mean difference 3.28; 95% confidence interval 1.45, 5.12) at the end of follow-up.

Conclusions

RVS pacing exhibited a higher LVEF after long-term follow-up than RVA pacing. RVS pacing could replace the previously used RVA pacing as a better alternative with improved clinical outcomes. However, there remains a need for larger RCTs to compare the safety and efficacy of RVS with RVA pacing.

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography

BACKGROUND

Recently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block.

METHODS

We compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography.

RESULTS

RVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5 ms, P<0.001). In contrast, RVOT pacing revealed a greater GLS (-14.69±4.92 vs -13.12±4.76 and -13.51±4.81%, P<0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P=0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7 ms, P=0.002) compared with RVA and RVMS pacing.

CONCLUSIONS

These results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

ECG Patterns In Cardiac Resynchronization Therapy

Cardiac resynchronization therapy is an established treatment modality in heart failure. Though non-response is a serious issue. To address this issue, a good understanding of the electrical activation during underlying intrinsic ventricular activation, biventricular as well as right- and left ventricular pacing is needed. By interpreting the 12-lead electrocardiogram, possible reasons for suboptimal treatment can be identified and addressed. This article reviews the literature on QRS morphology in cardiac resynchronization therapy and its role in optimization of therapy.

Medium-term effects of septal and apical pacing in pacemaker-dependent patients: a double-blind prospective randomized study

BACKGROUND

Pacing the right ventricle is established practice, but there remains controversy as to the optimal site to preserve hemodynamic function.

AIMS

To evaluate clinical and hemodynamic differences between apical and septal pacing in pacemaker-dependent patients.

METHODS

Patients receiving their first pacemaker for advanced atrioventricular block, with the atria in sinus rhythm, were randomized to receive apical (Group A) or septal (Group S) ventricular leads. After implant, with the device programmed VVI 70 beats/min fixed rate, patients underwent a 6-minute walk test and a transthoracic echocardiogram. Then, DDDR was programmed at nominal settings. The same tests were performed at 6 months and 12 months follow-up. If ventricular pacing was less than 98%, the patient was excluded.

RESULTS

A total of 142 patients were included in the study. During the study year, 71 (50%) were excluded for not fulfilling the condition of 98% ventricular pacing. Groups A and S had 34 and 37 patients, respectively. Age and gender were similar in the groups. At implant, QRS duration was significantly greater in Group A (158 ms) than Group S (146 ms; P = 0.018), and the QRS axis was different: -74.5° in Group A and 1° in Group S (P < 0.001). At 1 year, the 6-minute walk improved significantly in both groups: Group A 15% (P = 0.048) and Group S 24% (P = 0.001). Left ventricular ejection fraction (LVEF) increased from 0.57 to 0.61 (P = 0.008) in Group S, without significant change in Group A.

CONCLUSIONS

After 1 year, pacemaker-dependent patients with septal ventricular leads have better clinical and functional (LVEF) outcome.

Right ventricular septal pacing preserves global left ventricular longitudinal function in comparison with apical pacing: analysis of speckle tracking echocardiography

BACKGROUND

Right ventricular (RV) pacing alters left ventricular (LV) mechanical activation, resulting in adverse impacts on LV function. This study was aimed to investigate the acute effect of RV apical (RVA) and septal pacing (RVS) on LV dyssynchrony and function using speckle tracking echocardiography.

METHODS AND RESULTS

The 103 patients (749 years) with symptomatic bradyarrhythmia and preserved LV ejection fraction, and 50 age-matched control subjects were studied. All patients received a permanent pacemaker and were randomly assigned into 2 groups (RVA: n = 51, RVS: n = 52). After insertion, patients underwent an echocardiographic study during RV pacing. LV dyssynchrony and global strain parameters were analyzed using speckle tracking echocardiography. The QRS width and dyssynchrony indices by longitudinal and radial strain were significantly greater in RVA than in both the control and RVS. The LV longitudinal dyssynchrony index was significantly related to global longitudinal strain (GLS) among 103 patients receiving RV pacing (R² = 0.25, P < 0.0001). The GLS in RVA were the lowest among the 3 groups (GLS:

CONTROL

-18.22.4%, RVA: -14.33.1%, P < 0.001 vs. control, RVS: -16.82.7%, P<0.01 vs. RVA).

CONCLUSIONS

RVA created heterogeneous LV contraction, which resulted in deteriorated LV longitudinal contraction. RVS could be a better pacing alternative in terms of less LV dyssynchrony and better longitudinal function compared to RVA.

Atrioventricular nodal ablation versus antiarrhythmic drugs after permanent pacemaker implantation for bradycardia-tachycardia syndrome

Patients often require antiarrhythmic drugs to control tachycardia after permanent pacemaker implantation (PMI) for bradycardia-tachycardia syndrome. We compared atrioventricular nodal ablation (AVNA) to antiarrhythmic drugs after PMI for bradycardia-tachycardia syndrome. Twenty-eight symptomatic patients with bradycardia-tachycardia syndrome, all of which had a long pause after termination of paroxysmal atrial fibrillation, underwent PMI with RV lead placement at the mid-septum site. Among these patients, 14 underwent PMI and AVNA (AVNA group). The remaining 14 patients underwent PMI only, and continued to take anti-arrhythmic drugs (drug group). We compared cardiac function (cardio-thoracic ratio on chest X-ray, left atrial diameter, left ventricular end-diastolic dimension, and left ventricular-ejection fraction by echocardiography), exercise tolerance (6-min walking distance), symptoms, and the number of antiarrhythmic drugs just before and 6 months after PMI. Baseline characteristics were similar between the two groups, except for the number of antiarrhythmic drugs. Six months after PMI, cardiac function, exercise tolerance, and symptoms did not differ significantly between the two groups. Compared to the drug group (p < 0.01), the number of antiarrhythmic drugs was significantly smaller in the AVNA group 6 months after PMI. Patients who underwent AVNA concurrently with PMI with RV lead placement at the mid-septum site for bradycardia-tachycardia syndrome were able to reduce the intake of drugs and improve their tachycardia-related symptoms while maintaining cardiac function and exercise tolerance.

Fetal echocardiographic assessment of endocardial fibroelastosis in maternal anti-SSA antibody-associated complete heart block

BACKGROUND

There are few reports describing the features of maternal anti-SSA antibody-associated congenital complete heart block (CCHB) patients developing endocardial fibroelastosis (EFE). The aim of this study was to describe the clinical features and the outcome of patients with CCHB, with or without EFE.

METHODS AND RESULTS

Over a 20-year period, 12 consecutive patients diagnosed with maternal anti-SSA antibody-associated CCHB were identified. The maternal anti-SSA antibody levels were measured and fetal echocardiographic findings were reviewed. The ratios of the thickness of the endocardium to that of the whole wall of the left ventricle (LE/W) and right ventricle (RE/W) were measured to investigate the degree of endocardial thickening. A total of 7 patients survived (living group) and were not diagnosed as having EFE. The remaining 5 patients died and were diagnosed with EFE during autopsy (dead group). Fetal echocardiography of the patients showed differences in the thickening and hyperintensity of the endocardium. The RE/W value was significantly higher in the dead group than in the living group. The titers of both maternal anti-52-kDa and anti-60-kDa SSA antibodies were high, but showed no significant differences between the 2 patient groups.

CONCLUSIONS

EFE was the major negative prognostic factor for CCHB. Myocardial damage, predominantly in the right ventricle, was related to the outcome of CCHB associated with EFE.