Magnetocardiographic study of patients with right and left bundle branch blocks

Donatella Brisinda, Riccardo Fenici

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Intraventricular conduction disturbances can be usually registered as complete bundle branch blocks (cBBB): right (RBBB) or left (LBBB), as hemiblocks: anterior-left (LAH) or posterior-left (LPH), isolated or in combination with RBBB. LBBB often creates problems in ECG diagnosis of ischemic heart disease (IHD). It has been recently proposed that magnetocardiographic (MCG) mapping can be useful for early diagnosis of IHD also in patients with LBBB; however MCG patterns of cBBB in the absence of IHD have not been described. This study was aimed to define typical magnetic field (MF) distribution (MFD) patterns, during ventricular depolarization (QRS) and repolarization (VR), in patients with cBBB. Methods 36 patients (pts) with ECG diagnosis of cBBB [14 RBBB, 18 LBBB (2 with IHD), 4 RBBB+LAH] and 33 healthy subjects (HS) were consecutively investigated with an unshielded 36-channels DC SQUID MMCG system (sensitivity is 20 fT/Hz½, at 1 Hz) recording the z component of cardiac MF from a 36-point grid (20 x 20 cm). MFD maps and MF gradient orientation (MFGO) were analyzed with a time resolution of 2 ms. Quantitative analysis of VR was performed utilizing automated MCG analysis program according to preset T-wave parameters. Results In RBBB pts, the direction of septal depolarization was normal (avg. MFGO: 67.2°±17.4). A significant (p<0.001) difference of Rpeak MFGO was observed between RBBB pts with (52.8°±15) and without (-50.8± 28.5) cardiac abnormalities (CaAb), or associated with LAH (-148°±17.3). In pts with RBBB + LAH, average ST and Tpeak MFGO values were different (p<0.01 and p<0.05, respectively) from those of pts with RBBB only. All pts with LBBB had cardiac abnormalities, mostly dilated cardiomyopathy (DCM). As compared to HS, LBBB was characterized by an inversion (from right-to-left) of the direction of septal activation (-49.9°±20.9), a counterclockwise rotation of Rpeak MFGO (-113.4°±7.6) and an inversion of ST and Tpeak MFGO (61.4°±14.1 and 57.9°±14.1, respectively). In the 2 IHD pts, no difference of T-wave parameters was found. In one post-myocarditis DCM, ST and Tpeak MFGO rotated clockwise, toward more positive values. Discussion MCG differentiates RBBB associated with CaAb. MCG detection of ischemia in LBBB remains questionable
Original languageEnglish
Title of host publicationAbstracts Book
Pages220
Number of pages1
Publication statusPublished - 2006
Event15th International Conference on Biomagnetism. BIOMAG 2006 - Vancouver
Duration: 20 Aug 200626 Aug 2006

Conference

Conference15th International Conference on Biomagnetism. BIOMAG 2006
CityVancouver
Period20/8/0626/8/06

Keywords

  • Magnetocardiographic study
  • right and left bundle branch blocks

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