title: Comparison of electrophysiological parameters of septal and apical endocardial cardiac stimulation.
abstract: BACKGROUND
  The conventional right ventricle (RV) endocardial pacing leads QRS widening and desynchronization myocardial compromising ventricular function. With the need for stimulation less deleterious, RV septal pacing has been used more. Eventually have been reported higher thresholds and smaller R waves in the septal stimulation.
  
  
  OBJECTIVE
  To compare the parameters of the septal and apical stimulation, intra-patient, if there are any differences that may affect the choice of the point of stimulation.
  
  
  METHODS
  A prospective controlled study. We included 25 patients, 67.2±9 years, 10 (40%) women with indications for pacemaker for bradyarrhythmias. Etiologies were degenerative in nine (36%), Coronary disease in eight (32%), Chagas disease in seven (28%), and valve disease in one (4%) patient. Electrodes were active fixation and assessed the thresholds of command, impedance and R wave in uniand bipolar implant and after six months.
  
  
  RESULTS
  The average acute threshold command, R wave and impedance unipolar / bipolar septais x apicais were respectively 0.73 x 0.73V and 0,74V x 0,78V; 10 x 9,9mV and 12,3 x 12,4mV; 579 x 621Ω and 611 x 629Ω. Comparisons between parameters with septal and apical two-tailed paired t-test showed a P > 0.1. After six months, the mean control thresholds, R wave impedances and unipolar/bipolar septais x apicais were respectively 0.5V x 0 72V and 0.71V x 0,87V; 11.4 x 9,5mV and 12x11,2mV; 423x426 Ω and 578x550 Ω, with P > 0.05, except compared to unipolar pacing threshold septal apical unipolar P 0.02.
  
  
  CONCLUSIONS
  Using intra-patient comparisons, no significant differences between electrophysiological parameters septal and apical pacing and there are no restrictions for choosing the right ventricular septal pacing.
authors.affiliation: Instituto Dante Pazzanese de Cardiologia, São Paulo, SP, Brasil.
authors.forename: Juan Carlos Pachón
authors.initials: JC
authors.lastname: Mateos
authors.forename: José Carlos Pachón
authors.initials: JC
authors.lastname: Mateos
authors.forename: Remy Nelson Albornoz
authors.initials: RN
authors.lastname: Vargas
authors.forename: Enrique Indalécio Pachón
authors.initials: EI
authors.lastname: Mateos
authors.forename: Khalil
authors.initials: K
authors.lastname: Cosac
authors.forename: Hugo Belloti
authors.initials: HB
authors.lastname: Lopes
authors.forename: Fabrizio Achilles
authors.initials: FA
authors.lastname: Soares
authors.forename: Amanda Guerra Moraes Rego
authors.initials: AG
authors.lastname: Sousa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000379:methods*; D058409:Cardiac Resynchronization Therapy Devices / Q000009:adverse effects; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology / Q000628:therapy; D004562:Electrocardiography; D004567:Electrodes, Implanted; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006346:Heart Septum / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D013997:Time Factors; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology*