title: [Usefulness of superficial electrocardiogram in the diagnosis of narrow QRS tachycardias: correlation with intracavitary electrocardiograms].
abstract: OBJECTIVE
  The electrocardiogram is an important tool to diagnose tachycardias. The sequence of analysis of the superficial electrocardiogram was evaluated for the diagnosis of supraventricular tachycardias with narrow QRS complexes (<= 110 ms) establishing correlation with intracavitary electrograms.
  
  
  METHODS
  Between November 1996-October 1998, 674 electrophysiological studies were revised. 173 cases were selected, during which supraventricular tachycardias were inducted. In each study, the superficial electrocardiographic leads were correlated with the intracavitary electrograms during tachyarrhythmias. The P waves were located with respect to the R waves, the R-T or T-R' intervals, and the T waves, and relations between atrioventricular and ventriculoatrial intervals were established with the P-R' and R-P intervals, respectively, in the electrocardiogram.
  
  
  RESULTS
  107 patients were female. Upon locating the P waves in the electrocardiogram, in each supraventricular tachycardia we observed: a) P waves coincided with the R waves: 30 typical nodal reentries; b) P waves between R and T waves: 95 orthodromic atrioventricular reentries, 27 nodal reentries, 1 atrial tachycardia; c) P waves between T and R' waves: 4 nodal reentries, 5 orthodromic atrioventricular reentries, 7 atrial tachycardias, and <Id) P waves over T waves: 3 orthodromic atrioventricular reentries, and 1 nodal reentry.
  
  
  CONCLUSIONS
  The sequence of analysis locating the P waves in the superficial electrocardiogram is an useful, rapid method, with adequate sensitivity or specificity, in the evaluation of the mechanisms that sustain more common supraventricular tachycardias, permitting the performance of differential diagnosis between some of them.
authors.affiliation: Departamento de Cardiología, Hospital Regional Universitario José María Cabral y Báez, Santiago, República Dominicana. dhernandez@codetel.net.do
authors.forename: D
authors.initials: D
authors.lastname: Hernández
authors.forename: J
authors.initials: J
authors.lastname: Santiago
authors.forename: L
authors.initials: L
authors.lastname: Colin
authors.forename: P
authors.initials: P
authors.lastname: Iturralde
authors.forename: M
authors.initials: M
authors.lastname: Guevara
authors.forename: J A
authors.initials: JA
authors.lastname: González-H
mesh_terms: D000704:Analysis of Variance; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D012189:Retrospective Studies; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000503:physiopathology