Distal His bundle pacing in a patient with surgically corrected complex Ebstein anomaly and symptomatic second-degree atrioventricular block: a case report

Background

Ebstein's anomaly occurs when there is an apical displacement of the tricuspid valve with septal and posterior valve leaflets tethering. This condition often occurs in association with other congenital, structural, or conduction system diseases, including intracardiac shunts, valvular lesions, arrhythmias, accessory conduction pathways, and first-degree atrioventricular (AV) block. We present for the first time a case of a patient with Ebstein's anomaly who presented with second-degree Mobitz II AV block and was successfully treated with conduction system pacing (CSP) due to her young age and the likelihood of a long-term high percentage of pacing.

Case summary

We present a case of a 42-year-old lady with a background of complex congenital heart disease, including severe pulmonary stenosis, Ebstein anomaly, and atrial septal defect (ASD). She required complex surgical intervention, including tricuspid valve (TV) repair and subsequently replacement, ASD closure, and pulmonary balloon valvuloplasty. She presented to our hospital with symptomatic second-degree Mobitz II AV block (dizziness, shortness of breath, and exercise intolerance) and right bundle branch block (RBBB) on her baseline ECG. Her echocardiogram showed dilated right ventricle (RV) and left ventricle (LV) with low normal LV systolic function. Due to her young age and the likelihood of a long-term high percentage of RV pacing, we opted for CSP after a detailed discussion and patient consent. The distal HIS position is the preferred pacing strategy at our centre. We could not cross the TV with the standard Medtronic C315 HIS catheter, so we had to use the deflectable C304 HIS catheter. Mapping and pacing of the distal HIS bundle were achieved by Medtronic Selectsecure 3830, 69 cm lead. HIS bundle pacing led to the correction of both second-degree Mobitz II AV block and pre-existing RBBB. The implantation was uneventful, and the patient was discharged home the next day without any acute complications.

Discussion

Distal HIS pacing is feasible in patients with surgically treated complex Ebstein anomaly and heart block. This approach can normalize the QRS complex with a high probability of preserving or improving LV function.

Effectiveness of conduction system pacing for cardiac resynchronization therapy: A systematic review and network meta-analysis

INTRODUCTION

Cardiac resynchronization therapy (CRT) with biventricular pacing (BiV-CRT) is ineffective in approximately one-third of patients. CRT with Conduction system pacing (CSP-CRT) may achieve greater synchronization. We aimed to assess the effectiveness of CRT with His pacing (His-CRT) or left bundle branch pacing (LBB-CRT) in lieu of biventricular CRT.

METHODS AND RESULTS

The PubMed, Embase, Web of Science, Scopus, and the Cochrane Library were systematically searched until August 19, 2023, for original studies including patients with reduced left ventricular ejection fraction (LVEF) who received His- or LBB-CRT, that reported either CSP-CRT success, LVEF, QRS duration (QRSd), or New York Heart Association (NYHA) classification. Effect measures were compared with frequentist network meta-analysis. Thirty-seven publications, including 20 comparative studies, were included. Success rates were 73.5% (95% CI: 61.2-83.0) for His-CRT and 91.5% (95% CI: 88.0-94.1) for LBB-CRT. Compared to BiV-CRT, greater improvements were observed for LVEF (mean difference [MD] for His-CRT +3.4%; 95% CI [1.0; 5.7], and LBB-CRT: +4.4%; [2.5; 6.2]), LV end-systolic volume (His-CRT:17.2mL [29.7; 4.8]; LBB-CRT:15.3mL [28.3; 2.2]), QRSd (His-CRT: -17.1ms [-25.0; -9.2]; LBB-CRT: -17.4ms [-23.2; -11.6]), and NYHA (Standardized MD [SMD]: His-CRT:0.4 [0.8; 0.1]; LBB-CRT:0.4 [-0.7; -0.2]). Pacing thresholds at baseline and follow-up were significantly lower with LBB-CRT versus both His-CRT and BiV-CRT. CSP-CRT was associated with reduced mortality (R = 0.75 [0.61-0.91]) and hospitalizations risk (RR = 0.63 [0.42-0.96]).

CONCLUSION

This study found that CSP-CRT is associated with greater improvements in QRSd, echocardiographic, and clinical response. LBB-CRT was associated with lower pacing thresholds. Future randomized trials are needed to determine CSP-CRT efficacy.

His-bundle Pacing as a Bailout Therapy for a Patient with Subclavian Stenosis and No Suitable Coronary Sinus Branch: A Double Whammy

We present an interesting case of an 88-year-old man who was referred to our arrhythmia service for an upgrade of his dual-chamber pacemaker to a biventricular pacemaker for right ventricular pacing-induced cardiomyopathy. The patient was found to have stenosis of the left subclavian vein. Here, we describe the approach used to perform venoplasty in this patient. After venoplasty of the left subclavian vein, the patient did not have suitable coronary venous anatomy for deployment of the coronary sinus lead. Subsequently, a His lead was implanted. We achieved significant narrowing of the QRS with good thresholds and other lead parameters. Through this case report, we seek to present our approach of venoplasty in patients with occluded venous access for either an upgrade or a de novo implant.

The Atrioventricular Conduction Axis and its Implications for Permanent Pacing

Extensive knowledge of the anatomy of the atrioventricular conduction axis, and its branches, is key to the success of permanent physiological pacing, either by capturing the His bundle, the left bundle branch or the adjacent septal regions. The inter-individual variability of the axis plays an important role in underscoring the technical difficulties known to exist in achieving a stable position of the stimulating leads. In this review, the key anatomical features of the location of the axis relative to the triangle of Koch, the aortic root, the inferior pyramidal space and the inferoseptal recess are summarised. In keeping with the increasing number of implants aimed at targeting the environs of the left bundle branch, an extensive review of the known variability in the pattern of ramification of the left bundle branch from the axis is included. This permits the authors to summarise in a pragmatic fashion the most relevant aspects to be taken into account when seeking to successfully deploy a permanent pacing lead.

A case report of simultaneous His pacemaker implantation and atrioventricular junction ablation following unsuccessful treatment of atrial fibrillation

BACKGROUND

Atrial fibrillation can contribute to heart failure. Frequently, rhythm control is unachievable. Atrioventricular (AV) junction ablation and pacemaker implantation remain to be a therapeutic option for rate control in atrial fibrillation. Interventricular asynchrony is a potential downside of right ventricular pacing. However, cardiac resynchronization therapy and His pacing restore physiological activation sequences of the ventricles.

CASE SUMMARY

The reported patient had undergone several interventions to cure atrial fibrillation without sufficient rhythm control and experienced deleterious effects of recurrent arrhythmias. Finally, we decided to ablate the AV junction simultaneously with the implantation of a His bundle pacemaker. Atrioventricular junction ablation had to be repeated following conduction recurrence. A left-sided transaortic approach was required to create a permanent effect and to avoid distal lesions. His pacing was not affected by the AV junction ablation at all. The pre-existing widened QRS was normalized by His pacing, the patient became free of any complaints with full restoration of exertion capability.

DISCUSSION

His pacing has the potential to contribute to a revival of the 'ablate-and-pace' concept for incurable atrial fibrillation by restoring physiological ventricular activation, thereby overcoming the particular drawbacks of continuous ventricular pacing. Atrioventricular junction ablation simultaneously with the pacemaker implantation procedure is safe and feasible. His pacing is at least an alternative for cardiac resynchronization therapy. The implantation procedure is sometimes challenging.

Transient rise in His-lead threshold due to acute myocardial infarction

An 85-year-old male was admitted to our center with a non-ST elevation myocardial infarction. The patient had a dual-chamber pacemaker in situ with an atrial and His lead. A transient increase in His threshold and loss of nonselective capture occurred at the presentation of right coronary artery infarction, peaking during rotational atherectomy therapy causing loss of capture and complete atrioventricular block. A follow-up interrogation, 2 weeks postrevascularization, showed a return to a normal nonselective capture morphology and threshold measurements. Physicians should be aware of this complication in patients with His leads, particularly those with a history of coronary artery disease.

Painful left bundle branch block syndrome treated with his bundle pacing

This is a case report of a patient with painful LBBB Syndrome that responded favorably to His Bundle Pacing. This syndrome is largely under recognized despite 50 reports in the literature over the last 60 years. Both diagnosis and treatment are not well defined and represent a major challenge in patients with this entity. Right ventricular pacing has been attempted with inconsistent efficacy outcomes. We report for the first-time complete resolution of chest pain with His bundle pacing. HBP provides a promising alternative pacing option that might provide symptom resolution to patients with a painful LBBB syndrome.

Venous System Interventions for Device Implantation

Subclavian obstruction is common after lead implantation and the need to add or replace a lead is increasing. Subclavian venoplasty (SV) is a safe and effective option for venous occlusion. Peripheral venography overestimates the severity of the obstruction. A wire can usually be advanced into the central circulation for SV. Compared with dilators, SV improves the quality of venous access, providing unrestricted catheter manipulation for His bundle pacing and left ventricular lead implantation. SV preserves venous access and reduces lead burden. SV can easily be added to the implanting physicians lead management options.

An Underutilized Strategy

Atrioventricular (AV) node ablation is a commonly performed procedure for patients with chronic drug refractory atrial fibrillation (AF) with episodes of rapid ventricular response. We report on a 72-year-old man who had difficulty managing chronic drug refractory AFs with frequent hospitalizations for rapid ventricular rate. The patient was taken to the electrophysiology laboratory for AV node ablation. Extensive mapping and localization techniques of the compact AV node and ablation in the region were unsuccessful. Subsequently, high-output His bundle pacing using 20 mA at 2 ms of output energy was performed in an attempt to localize the His bundle in areas where high-output pacing resulted in a narrower QRS complex. Further ablations in the areas where pacing produced a narrower QRS complex resulted in complete heart block. This case highlights the importance of using this simple pacing maneuver to achieve complete heart block in patients in whom standard strategies to localize and ablate the compact AV node are unsuccessful.

Atrioventricular Optimized Direct His Bundle Pacing Improves Acute Hemodynamic Function in Patients With Heart Failure and PR Interval Prolongation Without Left Bundle Branch Block

OBJECTIVES

The purpose of this study was to investigate whether heart failure patients with narrow QRS duration (or right bundle branch block) but with long PR interval gain acute hemodynamic benefit from atrioventricular (AV) optimization. We tested this with biventricular pacing and (to deliver pure AV shortening) direct His bundle pacing.

BACKGROUND

Benefits of pacing for heart failure have previously been indicated by acute hemodynamic studies and verified in outcome studies. A new target for pacing in heart failure may be PR interval prolongation, which is associated with 58% higher mortality regardless of QRS duration.

METHODS

We enrolled 16 consecutive patients with systolic heart failure, PR interval prolongation (mean, 254 ± 62 ms) and narrow QRS duration (n = 13; mean QRS duration: 119 ± 17 ms) or right bundle branch block (n = 3; mean, QRS duration: 156 ± 18 ms). We successfully delivered temporary direct His bundle pacing in 14 patients and temporary biventricular pacing in 14 participants. We performed AV optimization using invasive systolic blood pressure obtaining parabolic responses (mean R²: 0.90 for His, and 0.85 for biventricular pacing).

RESULTS

The mean increment in systolic BP compared with intrinsic ventricular conduction was 4.1 mm Hg (95% confidence interval [CI]: +1.9 to +6.2 mm Hg for His and 4.3 mm Hg [95% CI: +2.0 to +6.5 mm Hg] for biventricular pacing. QRS duration lengthened with biventricular pacing (change = +22 ms [95% CI: +18 to +25 ms]) but not with His pacing (change = +0.5 ms [95% CI: -2.6 to +3.6 ms).

CONCLUSIONS

AV-optimized pacing improves acute hemodynamic function in patients with heart failure and long PR interval without left bundle branch block. That it can be achieved by single-site His pacing shows that its mechanism is AV shortening. The improvement is ∼60% of the effect size previously reported for biventricular pacing in left bundle branch block. Randomized, blinded trials are warranted to test for long-term beneficial effects.