The coherence spectrum. A quantitative discriminator of fibrillatory and nonfibrillatory cardiac rhythms

K M Ropella, A V Sahakian, J M Baerman, S Swiryn
1989 Circulation  
Previous work has suggested that a comparison of electrograms from two or more sites may best differentiate fibrillatory from nonfibrillatory rhythms. The coherence spectrum is a measure by which two signals may be compared quantitatively in the frequency domain. In the present study, the coherence spectrum was used to quantify the relation between spectral components of electrograms from two sites in either the atrium or ventricle during both fibrillatory and nonfibrillatory rhythms. Bipolar
more » ... cordings of 35 rhythms from 20 patients were analyzed for coherence in the 1-59 Hz band. The 17 nonfibrillatory rhythms were sinus rhythm (six), paroxysmal supraventricular tachycardia (two), atrial flutter (four), and monomorphic ventricular tachycardia (five). The 18 fibrillatory rhythms were atrial fibrillation (12) and ventricular fibrillation (six). Nonfibrillatory rhythms exhibited moderate-to-high levels of coherence throughout the 1-59 Hz band, with peaks concentrated at the rhythm's fundamental frequency and its harmonics. Fibrillatory rhythms exhibited little coherence throughout the 1-59 Hz band, and harmonics were not evident. The mean magnitude-squared coherence (scale of 0 to 1) for the 1-59 Hz band ranged from 0.22 to 0.86 (mean± SD, 0.52 ±0.19) for nonfibrillatory rhythms and from 0.042 to 0.12 (0.067±0.021) for fibrillatory rhythms. Separation of fibrillatory and nonfibrillatory rhythms was possible whether signals were recorded by floating or fixed-electrode configurations. These findings indicate that comparison of two electrograms with magnitude-squared coherence measurements differentiates fibrillatory from nonfibrillatory rhythms. A recognition algorithm based on coherence spectra may be robust in the face of major variations in lead configuration. Furthermore, the coherence spectra may provide a means to quantify the "organization" or "disorganization" of a cardiac rhythm. (Circulation 1989;80:112-119) F ibrillatory rhythms are typically described as "chaotic" and "disorganized." More specifically, the activity from multiple sites during fibrillation has been described as asynchronous and incoordinate.1-6 Allessie et a16 have suggested that the comparison of activity from two or more sites may best differentiate fibrillatory from nonfibrillatory rhythms. While this "altered spatial arrangement of conduction"7 is quintessential to fibrillation, this qualitative characteristic remains to be quantified. Previous studies have used frequency From the
doi:10.1161/01.cir.80.1.112 pmid:2736743 fatcat:bmqtfzuflreo7c3oig6fchty7i