gms | German Medical Science

In recent years, analysis of baroreceptor sensitivity (BRS) has become an important factor in characterizing cardiovascular regulation. Various techniques for estimation of the spontaneous BRS were established: e.g. alpha method (frequency domain analysis), Z-analysis (statistical method) and dual sequence method (DSM, standard sequence method with slope sector distribution quantification and time shifting). All methods are based on the calculation of the slope between systolic blood pressure and heart rate.

These methods were applied in a group of 20 patients suffering from dilated cardiomyopathy (DCM, EF: 29.5±11.2% (NYHA II-III)) and 20 healthy volunteers (CON). The electrocardiogram and non-invasive continuous blood pressure were recorded for 30 minutes from all subjects.

All three methods were suitable to detect significant differences in BRS control between DCM and CON (average slope with DSM, DCM: 7.47±2.18ms/mmHg, CON: 9.37±3.30ms/mmHg, p < 0.01). The calculated average slopes differed between the three methods however remains significant between both groups.

While alpha method and Z-analysis only allow to estimate the average slope, the DSM includes additional parameters: BRS activation, that means how many blood pressure increases/decreases lead to heart rate responses (DCM: 24.4±14.4%, CON: 30.8±14.6%, p < 0.05), as well as the slope sector distribution quantification (e.g. relative portion of sector 4-6ms, DCM: 23.7±12.4%, CON: 15.8±8.3%, p < 0.01). Obviously, the DSM offers a more detailed characterization of the examined BRS regulation in contrast to the other compared methods.

All examined methods are suitable to calculate BRS and classify DCM patients and controls. The calculated BRS are not directly comparable between the applied methods, but there is a correlation between them. Our study demonstrated that BRS slope is not the only baroreflex parameter; a more detailed analysis with the DSM could lead to independent information about the BRS regulation