Atrial fibrillation (AF) is a common arrhythmia characterized by irregular ventricular response. During AF, beat-to-beat variability of arterial pressure (AP) is increased because of continuous changes in filling time, stroke volume and contractility. Only a few studies have analyzed short-term AP variability during AF but they were mainly focused on the effects of respiration. We therefore analyzed short-term systolic (S), diastolic (D) and mean (M) AP variability by autoregressive method and an FFT-based spectral estimation (Welch periodogram) in 26 patients with persistent AF before and after restoration of sinus rhythm by electrical cardioversion. A low frequency (LF) component (central frequency 0.07±0.02 Hz, mean±standard deviation) of SAP variability was observed in 23 out of 26 patients during AF. Frequency analysis of DAP and MAP also showed a LF component with a central frequency of 0.08±0.03 Hz (20 patients) and 0.07±0.03 Hz (25 patients), respectively. After recovery of sinus rhythm, we found significant reduction in mean SAP, DAP and MAP variability in all frequency bands. Squared coherence between SAP and heart rate variability after recovery of sinus rhythm revealed a weak and strong coupling within, respectively, LF and HF frequency bands. These data indicate that in patients with AF, in spite of an absence of rhythmical oscillation in RR interval time series, it is possible to observe a LF component in SAP, DAP and MAP variability signals. These 0.1 Hz fluctuations reflect the influence of the sympathetic fibres acting on the cardiovascular system. During atrial fibrillation (AF), ventricular response is highly irregular and thus the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility. Aim of the present study is to investigate the short-term dynamics of RR and SAP series in patients with AF, during rest and tilt, and after restoration of sinus rhythm. We computed symbolic sequences of the three phases, as they retain important features of the dynamics generated by the underlying control system. Then we applied a method based on rank order statistics of symbolic sequences to investigate the profile of different types of dynamics. The linguistic distance (range 0–1) between sequences represents a measure of similarity to assess whether the different physiological states are reflected on the dynamics of RR and SAP series. The distance between rest and tilt phases is 0.06 ± 0.02 for RR series, meaning they are very similar, while it is 0.21 ± 0.13 for SAP series, showing a difference in the short term dynamics. RR mean decreases during tilt (738 ± 164 vs. 692 ± 152 ms, p < 0.05, rest vs. tilt), while mean SAP is not significantly different (101 ± 20 vs. 104 ± 14 mmHg, rest vs. tilt). Comparing AF and sinus rhythm, both RR and SAP series result different in terms of the computed distance. SAP short-term dynamics seem to significantly change when comparing rest and tilt phases, while RR series remain unchanged. Moreover, RR mean but not SAP series significantly decreased during tilt.
VALUTAZIONE DI UNA COMPONENTE A BASSA FREQUENZA DELLA VARIABILITÀ DELLA PRESSIONE ARTERIOSA SISTOLICA IN PAZIENTI CON FIBRILLAZIONE ATRIALE PERSISTENTE E SUA SUCCESSIVA ULTERIORE VALUTAZIONE MEDIANTE LINGUISTIC ANALYSIS / P. Terranova ; tutor: Federico Lombardi ; coordinatore: Fabio Magrini. - Milano : Università degli studi di Milano. Universita' degli Studi di Milano, 2010 Dec 17. ((23. ciclo, Anno Accademico 2010.
|Titolo:||VALUTAZIONE DI UNA COMPONENTE A BASSA FREQUENZA DELLA VARIABILITÀ DELLA PRESSIONE ARTERIOSA SISTOLICA IN PAZIENTI CON FIBRILLAZIONE ATRIALE PERSISTENTE E SUA SUCCESSIVA ULTERIORE VALUTAZIONE MEDIANTE LINGUISTIC ANALYSIS|
|Supervisori e coordinatori interni:||MAGRINI, FABIO|
|Data di pubblicazione:||17-dic-2010|
|Parole Chiave:||Atrial Fibrillation ; Sympathetic Nervous System ; Heart Rate Variability ; Arterial Pressure Variability|
|Settore Scientifico Disciplinare:||Settore MED/09 - Medicina Interna|
Settore MED/11 - Malattie dell'Apparato Cardiovascolare
|Citazione:||VALUTAZIONE DI UNA COMPONENTE A BASSA FREQUENZA DELLA VARIABILITÀ DELLA PRESSIONE ARTERIOSA SISTOLICA IN PAZIENTI CON FIBRILLAZIONE ATRIALE PERSISTENTE E SUA SUCCESSIVA ULTERIORE VALUTAZIONE MEDIANTE LINGUISTIC ANALYSIS / P. Terranova ; tutor: Federico Lombardi ; coordinatore: Fabio Magrini. - Milano : Università degli studi di Milano. Universita' degli Studi di Milano, 2010 Dec 17. ((23. ciclo, Anno Accademico 2010.|
|Appare nelle tipologie:||Tesi di dottorato|