Comparison of Cardiac Function Between Left Bundle Branch Pacing and Right Ventricular Outflow Tract Septal Pacing in Pacemaker-dependent Patients
Condition: Slow Arrhythmia; Left Bundle Branch Pacing; Cardiac Function
MeSH terms: Arrhythmias, Cardiac
Study type: Observational

Summary: 
      Permanent pacemaker implantation is a common method for bradycardia and cardiac conduction
      dysfunction. With the development of physiological pacing, the optimal location of
      ventricular pacing site is still improving. Traditional ventricular pacing site at the apex
      of right ventricle or septum of right ventricular outflow tract（RVOT）, causing iatrogenic
      left bundle branch block and asynchronous ventricular contraction, leading to cardiac
      remodeling, pacemaker-mediated cardiomyopathy and congestive cardiac failure. Long-term
      chronic ventricular pacing can lead to changes in endocardial myocytes and myofibrils and
      promote fibrosis. Thus, the alternative pacing site, HIS bundle pacing, has been sought
      later. The safety and feasibility of permanent HIS bundle pacing have been confirmed in
      patients with various cardiac diseases. However, the shortcomings of high and unstable
      threshold, long implantation time, low R-wave amplitude and HIS bundle damage during
      implantation limit the application of HIS pacing especially in patients with infra-Hisian
      block. Left bundle branch pacing(LBBP) is a new technique evolved from HIS bundle pacing. In
      2017, Huang et al[9]reported that LBBP was successfully paced using 3830 leads(Medronic Inc.
      USA). The advantages of narrow QRS duration, low threshold, high R wave amplitude, easy
      fixation and correction of left bundle branch block made LBBP more widely used in
      clinic.However, whether left bundle branch pacing is superior to traditional right
      ventricular outflow tract septal pacing in cardial function is still lack of sufficient
      evidence. The purpose of this study is aim to using Brain natriuretic peptide(BNP),
      echocardiography and speckle-tracking echocardiagraphy, six minutes walk test and quality of
      life to compare the changes of cardiac function within 1 month between LBBP and RVOP in
      pacemaker-dependent patients.
    

Detailed description: 
      The purpose of this study was to compare the changes of cardiac function within 1month in
      pacemaker-dependent patients between LBBP and RVOP. A single-center prospective random
      controlled clinical study was conducted in 60 patients with bradycardia indications. 30
      patients underwent RVOP and 30 patients underwent LBBP. The changes of BNP, echocardiogram
      and speckle-tracking echocardiagraphy, six minutes walk test and quality of life were
      compared between the two groups before and within 1month. The etiology of pacemaker
      implantation included high atrioventricular block, atrial fibrillation with slow arrhythmia.
      Implantation procedures: Left bundle branch pacing was achieved by trans-interventricular
      septum method in the basal ventricular septum and performed by using the Select pacing 3830
      lead(Medtronic Inc, USA) delivered through a fixed sheath(7F C315 HIS, Medtronic Inc, USA).
      During implantation, a unipolar configuration is used for pacing and recording. The delivery
      sheath was inserted through left subclavian vein into atrial side of the tricuspid valve to
      mark His bundle potential under right anterior oblique(20°) fluoroscopic view. As a marker in
      His bundle region, the sheath with the lead tip was further advanced towards the right side
      of the ventricular septum approximately 1.5-2cm, and paced QRS morphology showing left bundle
      branch block(LBBB) at output of 2V/0.4ms. When the sheath with the lead tip screwed to the
      left side of the septum, paced QRS morphology changed from LBBB to right bundle branch
      block(RBBB), a gradual change of the notch morphology("W" waveform) in lead V1 gradually
      shifted and finally disappeared.Another active electrode is implanted in the right
      auricle.Patients with RVOP: The right ventricular pacing lead was positioned in the low
      intervals of right ventricular outflow tract, and atrial active lead was positioned at right
      auricle. BNP was measured routinely before implantation and reexamined on 1 day and 1month
      after pacemaker implantation.Twelve-lead ECG were recorded including QRS duration, QRS
      amplitude and QT interval. Echocardiography data were measured by conventional transthoracic
      echocardiography system including left atrial anteroposterior dimension, left atrial
      transverse dimension, left atrial vertical dimension, e', peak E-wave velocity, peak A-wave
      velocity, E/A, E/e', left atrial ejection fraction (LAEF), left ventricular ejection fraction
      (LVEF), velocity-time integration of aortic blood flow(VTI). Left atrial strain and strain
      rate were measured by speckle-tracking echocardiography(STE).We also measure the six minutes
      walk test and quality of life in all patients before and after implantation in 1month.
    

Intervention name(s): pacemaker
Intervention type(s): Device
Intervention description(s): electrode is implanted in left bundle branch in LBBP; electrode is implanted in right ventricular outflow tract septal in RVOP
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Pacemaker-dependent patients who agreed to implant a pacemaker.