Cardiac autonomic control during balloon carotid angioplasty and stenting

Hemodynamic alterations during balloon carotid angioplasty (BCA) and stenting have been ascribed to the consequences of direct carotid baroreceptor stimulation during balloon inflation. BCA with stenting in patients with carotid atheromatous stenoses offers a unique opportunity for elucidating the cardiovascular autonomic response to direct transient intravascular stimulation of the baroreceptors. We analysed the consequences of BCA on the autonomic control of heart rate and on breathing components in nine patients with atheromatous stenoses involving the bifurcation and the internal carotid. A time-frequency domain method, the smoothed pseudo-Wigner-Ville transform (SPWVT), was used to evaluate the spectral parameters (i.e., the instantaneous amplitude and centre frequency (ICF) of the cardiovascular and respiratory oscillations). Those parameters and their dynamics (8 and 24 h later) were evaluated during and after the procedure. BCA stimulates baroreceptors in all patients, which markedly reduces heart rate and blood pressure. Vagal baroreflex activation altered the respiratory sinus arrhythmia in terms of amplitude and frequency (ICF HF RR shifted from 0.27 +/- 0.03 to 0.23 +/- 0.04 Hz pre-BCA vs. BCA, respectively; p < 0.01). Both the high- and low-frequency amplitudes of heart rate oscillations were altered during carotid baroreceptor stimulation, strongly supporting a contribution of the baroreflex to the generation of both oscillations of heart rate. Carotid baroreceptors stimulation increased the inspiratory time (Ti) (1.5 +/- 0.5 to 2.3 +/- 0.6 s pre-BCA vs. BCA, respectively; p < 0.01). In awake patients, BCA with stenting of atheromatous stenosis involving the bifurcation and internal carotid causes marked changes in the cardiac autonomic and respiratory control systems.