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Biomedical subjects

Vincent Pichot

Publications and source records attributed to Vincent Pichot.

At least 19 recordsLinked to original sources
PubMed2006

Modulations of human autonomic function induced by positive pressure-assisted breathing.

In order to examine the acute autonomic response in humans during and immediately after positive pressure-assisted (PPA) breathing, spontaneous cardiac baroreflex (BR) sensitivity was studied through the adaptation of consecutive RR intervals in response to spontaneous systolic blood pressure fluctuations in 11 healthy subjects. The gain (alpha-index) in baroreceptor reflex was estimated using cross-spectral analysis (RR interval variability and systolic blood pressure variability) for the low frequency (LF) and high frequency (HF) bands. All measurements were made under fixed breathing rate (12 breaths per minute), and realized consecutively at baseline level (20 min), after-short inspiratory pressure support plus positive end-expiratory airway pressure (IPS + PEEP) ventilation (15 min), again under normal conditions (20 min; recovery period) and, finally, during a standard upward orthostatic challenge test (15 min; orthostatic challenge). The spontaneous BR gain in the HF band increases slightly during ventilation (+26.1 +/- 11.7%, P<0.05) and decreases significantly during recovery without any significant alteration in mean heart rate, systolic or diastolic blood pressure. The spontaneous BR gain in the LF band decreases during IPS + PEEP ventilation (8.4 +/- 4.4 versus 12.7 +/- 6.2 ms mm(-1) Hg; P<0.05) and returns to basal level during recovery. Orthostatic challenge altered significantly the BR gain in both HF and LF bands with significant heart rate acceleration. In humans, while the parasympathetic control of heart rate and blood pressure is found moderately enhanced, the sympathetic BR drive appears significantly and transitory altered under short term IPS + PEEP ventilation with a degree of alteration comparable to those observed during orthostatic challenge.

Adult↗
PubMed2006

Nocturnal autonomic nervous system activity impairment in sickle cell trait carriers.

Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal haemoglobin (Hb) and marked by the heterozygous presence of HbA and HbS. Some studies have suggested that SCT carriers might be prone to vascular alterations, cardiac ischaemia and arrhythmias leading, in some subjects, to sudden death. It is well known that a loss or a disequilibrium of autonomic activity are powerful predictors of sudden cardiac death. We hypothesized that SCT subjects might exhibit alterations in the activity of the autonomic nervous system that could constitute further risk factors for cardiac complications. Resting haemorheological parameters (eta(b), blood viscosity; eta(p), plasma viscosity; Hct, haematocrit; Tk, red blood cell rigidity), and sympathetic and parasympathetic indices of nocturnal autonomic activity (temporal and frequency analysis of heart rate variability) were thus compared between a group of nine SCT subjects and a group of nine control subjects. eta(b) was higher in the SCT group than in the control group while Hct, eta(p) and Tk were not different. Global variability (SDNN, SDNNIDX) and parasympathetic (PNN50, RMSSD, HF) indices were significantly lower in the SCT group compared with the control group, while the LF/HF ratio was highly increased, underlining a major sympathetic shift. The autonomic imbalance in SCT subjects was mainly related to lowered parasympathetic activity. Thus, our study suggests an additional global decrease and imbalance of autonomic nervous system activity to biological disorders of SCT carriers, that may constitute further risk factors for cardiac complications in this population.

Adult↗
PubMed2006

Forelimb postischaemic reactive hyperaemia is impaired by hypotensive low body negative pressure in healthy subjects.

Local metabolic conditions adapt blood supply to metabolic requirement by a direct effect on vascular smooth muscles and indirectly by modulating sympathetic vasoconstrictor effectiveness. During exercise, sympathetic nervous activity could in turn interfere on local metabolic control of vascular tone and restrain blood flow to active muscles. In order to investigate that interaction non-invasively, we measured postischaemic reactive hyperaemia (RH) in the forelimb of eight healthy young men (22.7 +/- 2.1 years) at rest and during two levels of sympathetic stimulation using low body negative pressure (LBNP -15 and -30 mmHg). During every stages, RH was measured after 40, 60, 90 and 180 s of arterial occlusion, respectively. In control conditions, RH rose with duration of ischaemia (18.9, 24.2, 30.4, 33.1 ml min(-1) per 100 ml(-1) for 40, 60, 90 and 180 s of ischaemia, respectively). During non-hypotensive LBNP (-15 mmHg) sympathetic activation was associated with decreased forelimb blood flow (6.4 +/- 0.9 versus 3.9 +/- 0.6 ml min(-1) per 100 ml(-1), P<0.01), but RH were not significantly different from control conditions. During hypotensive tachycardia LBNP (-30 mmHg), RH were significantly lower than under the previous LBNP stage. This fall in RH was greater after the shortest gap of ischaemia and tapered off as arterial occlusion gap increased (-22.3, -13.1, -10.5 and -8.7% for 40, 60, 90 and 180 s of ischaemia, respectively). These results suggested that vascular tone adaptation to local metabolic conditions was modified by sympathetic nervous activation. This was particularly marked when an hypotensive-mediated sympathetic stimulation was opposed to short gaps of ischaemia.

Adult↗
PubMed2005

Refeeding normalizes the QT rate dependence of female anorexic patients.

We postulated that dynamic alterations in QT interval adaptation could characterize patients with anorexia nervosa (AN) and could be restored after weight gain. To assess ventricular repolarization features, we evaluated the QT dynamicity along RR intervals from 24-hour electrocardiographic data of patients with AN before and after refeeding. Ten young women with AN (19 +/- 3 years) were included in the study. The QT/RR slope was found significantly enhanced compared with normals (-1.82 +/- 0.62 vs -1.40 +/- 0.30; p < 0.05). This slope returned to normal range values after refeeding. The QT/RR slope was significantly correlated with the body mass index (r = 0.59; p < 0.007) in the patient group.

Adult↗
PubMed2005

Interval training in elderly men increases both heart rate variability and baroreflex activity.

AIMS: Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health. METHODS: We assessed maximal oxygen consumption (VO2max), autonomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in eleven elderly men (73.5+/-4.2 years) before and after a 14-week program of intensive cycloergometer interval training. The standard HRV indices were calculated using time domain (mean RR, PNN50, RMSSD, SDNN, SDANN and SDNNIDX), and Fourier transform (total power, ULF,VLF, LF, LFnu, HF, HFnu and LF/HF) analyses of 24-hour, daytime and nighttime Holter recordings. The SBR was calculated from 15-minute recordings of spontaneous blood pressure and RR interval variations using the sequence (slope, slSBR) and cross-spectral (alphaSBRHF and alphaSBRLF) methods. RESULTS: After the training period,VO2max increased by 18.6 % (26.8+/-4.4 to 31.8+/-5.2 ml.kg(-1).min(-1), p<0.01). The nocturnal parasympathetic indices of HRV increased (PNN50: 3.05+/-2.21 to 5.00+/-2.87%, RMSSD: 29.1+/-7.6 to 38.8+/-10.9 ms, HF: 117+/-54 to 194+/-116 ms2/Hz, all p<0.05) as did the SBR indices (slSBR: 7.0+/-1.8 to 9.8+/-2.1 ms.mmHg(-1), p<0.01; alphaSBRHF: 6.9+/-2.2 to 10.5+/-3.7 ms.mmHg(-1), p<0.05; alphaSBRLF: 5.3+/-2.3 to 6.9+/-3.1 ms.mmHg(-1), p=0.22). CONCLUSION: Intensive endurance training in elderly men enhanced parasympathetic parameters of HRV and, interestingly, of SBR. Physiological mechanisms and long-term clinical effects on health status should be further investigated.

Aged↗
PubMed2005

Cardiovascular variability during periodic leg movements: a spectral analysis approach.

OBJECTIVE: Changes in cardiovascular measures have been advocated as sensitive markers of phasic events arising from sleep. The current study was aimed to analyse the effects of periodic leg movements (PLMS) on heart rate variability (HRV) during NREM sleep in patients having restless legs syndrome and periodic leg movements during sleep. METHODS: The absolute and normalized high- and low-frequency peaks from spectral analysis (FFT) of R-R intervals, the HRV changes using wavelet transform, the geometric and time domain HRV were measured in 14 patients with restless legs syndrome and PLMS. The analysis was done comparing one hundred, 10 min periods with PLMS (PLMS+) and 60 periods without PLMS (PLMS-) in stage 2 of NREM sleep. In 8 patients analysis was also done in slow wave sleep (SWS). RESULTS: Occurrence of PLMS induced changes in geometrical indices of HRV, with a rise of the triangular index and the triangular interpolation of R-R intervals in PLMS+ periods (P < 0.0001). Small changes in time domain indices were found during PLMS+ periods, while the SD of the R-R intervals (SDNN), reflecting global HRV, was significantly higher (P = 0.001). While the low frequency (LF) power significantly increased in PLMS+ periods (P < 0.0001), high frequency (HF) power showed a weak and not significant reduction. The rise in sympathetic activity as detected by frequency domain HRV analysis was related to density and interval of PLMS. Comparison between sleep stages of NREM sleep demonstrated lower values of HRV measures when PLMS+ periods occur in SWS. CONCLUSIONS: Overall, PLMS occurrence was associated with a shift to increased sympathetic activity without significant changes in cardiac parasympathetic activity. The frequency domain analysis of HRV appears to be an easy tool to estimate the autonomic changes related to PLMS and PLMS- arousals and to differentiate their occurrence during stage 2 and deep sleep. SIGNIFICANCE: Spectral HRV measures may offer a simple approach to estimate the degree of autonomic changes occurring in relation to periodic leg movements in restless legs patients.

Adult↗
PubMed2005

Evidence of sequential lift in growth of aligned multiwalled carbon nanotube multilayers.

We synthesized aligned multiwalled carbon nanotube multilayers by aerosol-assisted catalytic chemical vapor deposition through sequential injections of aerosols containing both carbon and catalyst precursors. Each sequence was traced by a specific duration or precursor mixture, with the carbon source being possibly enriched in (13)C isotope labels. We discovered that any sequence involved the growth of a new layer on the substrate surface, under any pre-existing one by lifting it up, giving definitive evidence of a base-growth mechanism.

Aerosols↗
PubMed2005

Continuous positive airway pressure treatment improves the QT rate dependence adaptation of obstructive sleep apnea patients.

BACKGROUND: QT rate dependence is one of the major properties of ventricular repolarization, with its circadian and autonomic modulations. The alteration of cardiac autonomic tone occurring in obstructive sleep apnea syndrome (OSAS) patients could explain the altered rate-dependent adaptation of the myocardial repolarization. Thus, we postulated that dynamic alterations in QT interval adaptation could be ameliorated in OSAS patients under continuous positive airway pressure (CPAP) treatment. To assess ventricular repolarization features in patients with OSAS, we compared QT parameters and their dynamicities along RR intervals from 24-hour ECG. METHODS: The study groups consisted of 38 consecutive OSAS patients and 38 healthy age-matched subjects. The syndrome was confirmed for OSAS patients according to standard polysomnographic criteria (apnea plus hypopnea index: 56.9 +/- 28.4/h). A second polysomnography synchronized with 24-hour ECG Holter and realized under efficient CPAP therapy confirmed the control of sleep-related breathing disorder. RESULTS: QT length related to heart rate was found significantly altered in patients with OSAS compared with controls (QTend/RR slope: -0.126 +/- 0.031 vs -0.173 +/- 0.038; P < 0.01). This flattened relationship was significantly improved with the treatment of the OSAS (-0.151 +/- 0.051; P < 0.01 vs pretreatment status). There was no significant impact of CPAP therapy on ventricular ectopic activity as well as on static repolarization parameters (QT, RT, QTc, RTc) measured separately over daytime and nighttime. CONCLUSIONS: The prognostic implications of such findings and the protective role of CPAP treatment to prevent sudden cardiac death in OSAS need to be evaluated.

Analysis of Variance↗
PubMed2005

Relationship between daily physical activity and ANS activity in patients with CHF.

PURPOSE: Heart rate variability (HRV) indices are powerful independent prognostic factors of cardiovascular events and all cause mortality in patients with chronic heart failure (CHF). This study evaluates the influence of lifestyle on HRV in CHF patients. METHODS: Thirty-nine CHF patients (33 men, ischemic/dilated cardiomyopathy (18/21), 52.4 +/- 11.2 yr, NYHA I to III, LVEF 33.4 +/- 5.1%) filled out a physical activity questionnaire providing an individual complete qualitative and quantitative picture of their physical activity and daily energy expenditure (PAEE/DEE) corrected for age, weight, severity of the condition and autonomy. Frequency and time domain indices of HRV were calculated from ECG Holter recordings on a typical weekday. Nighttime indices were calculated in order to avoid the confounding factor of physical activity that might alter 24-h frequency analysis of HRV. RESULTS: DEE was significantly different between classes I and II and classes I and III (P = 0.01 both) patients. Time spent in activities above 3 METs decreased significantly with the severity of the condition. Global and parasympathetic indices of 24-h HRV analysis were correlated to DEE and PAEE (Ptot24h = 78.80*PAEE (J x min x kg) -1061.80, R = 0.72, P < 0.0001). Multiple regression analysis revealed that PAEE was the sole independent factor on established HRV prognostic indices (P < 0.05) and especially within PAEE dimensions, only activities above 3 METs were correlated with established prognostic HRV indices (P < 0.05). CONCLUSION: These results indicate that rather than total DEE, moderate to intensive physical activity may counteract the decline in HRV with chronic heart disease. This may be linked to longer time spent in higher intensity activities, and not to total activity time.

Adult↗
PubMed2004

Heart rate increment: an electrocardiological approach for the early detection of obstructive sleep apnoea/hypopnoea syndrome.

The prevalence of OSAHS (obstructive sleep apnoea/hypopnoea syndrome) is high in developed countries and it is estimated that the vast majority of patients remain undiagnosed. On the basis of physiological evidence, we evaluated the frequency component of HRI (heart rate increment) as a simple and inexpensive screening tool for OSAHS detection in a first group of patients (group 1) and validated their discriminant capacity in a second group (group 2). The predictive accuracy of hourly %VLFI (frequency-domain HRI variable obtained from nocturnal ECG Holter monitoring) was analysed by comparison with an hour-by-hour respiratory disturbances index assessed by complete polysomnography in 28 consecutive clinically suspected OSAHS patients for group 1 and in 35 patients for group 2. OSAHS was present in 20 patients according to a mean hourly apnoea plus hypopnoea index >10 in group 1, and prevalence reached 77.1% in group 2. Sensitivity, specificity and positive and negative predictive accuracy were calculated and an ROC (receiver operating characteristic) curve was constructed for several polysomnographic threshold values. In group 1, hourly %VLFI appeared as an evident predictor of the apnoea/hypopnoea index (W=0.848, P<0.0001; where W is the area under the curve obtained using ROC curve analysis). Using an appropriate threshold (value > or =3.2%), %VLFI demonstrated a sensitivity of 78.1% and a specificity of 70.4%. These thresholds applied to group 2 yielded a sensitivity of 73.9% and a specificity of 76.6%. Frequency-domain analysis of the HRI appears to be a powerful tool for OSAHS prediction. The simplicity of its analysis and use makes of it a particularly well-suited variable for routine mass screening in high-risk populations undergoing ECG Holter monitoring.

Adult↗
PubMed2004

Chronotropic incompetence to exercise separates low body weight from established anorexia nervosa.

Chronotropic incompetence (CI), characterized by an attenuated heart rate (HR) response to exercise could participate to the limitation of exercise capacity in anorexia nervosa (AN). Therefore, we evaluated the role of cardiac sympathetic responsiveness in AN patients. In addition, the ambulatory value of autonomic control using spectral analysis of heart rate variability (HRV) was determined and correlated to maximal exercise performance. Twenty-two patients hospitalized for weight loss and suspicion of AN were included in the study. All performed a symptom-limited exercise test with measurement of gas exchange for chronotropic response to exercise evaluation. Holter ECG recordings allowed daytime and night-time spectral domain HRV analysis in order to evaluate the alteration of sympathetic control of HR in free-living conditions. CI defined as a failure to achieve 80% of heart rate reserve (%HRR) was observed in 13 (59%) patients (CI+). This group presented a higher body mass deficit than the group without CI (CI-; -35.1 +/- 8.7% versus -26.1 +/- 10.7%; P<0.05). Obviously, patients with a lower body mass index (BMI < 16 kg m(-2), n = 14) revealed a more severe limitation to maximal exercise with a lower peak HR, a lower peak Vo(2), and a lower maximal O(2) pulse (P<0.05). BMI was significantly correlated to peak Vo(2), maximal HR, and %HRR achieved at peak exercise. Daytime HRV parameters reflecting the sympathetic autonomic equilibrium (LF nu, LF/HF ratio) were significantly lower in CI+ patients. Blunted sympathetic response to maximal exercise is frequent and correlated to weight deficit. The present data suggest a major autonomic derangement in AN characterized by a cardiac sympathetic withdrawal.

Adult↗
PubMed2004

Alteration of the QT rate dependence in anorexia nervosa.

Myocardial repolarization has been evaluated in patients with anorexia nervosa (AN) with conflicting results. The authors postulated that dynamic alterations in QT interval adaptation could characterize these patients. This study compared QT dynamicity along RR intervals from 24-hour ECG data of patients with and without AN. Twenty-five patients (23 women) fulfilling the Diagnostic and Statistical Manual (DSM IV) criteria for AN were included in the study. All underwent 24-hour ECG Holter recordings, allowing QT and RR measurements, and heart rate variability (HRV) analysis in free-living conditions. A group of 25 sex- and age-matched healthy subjects served as controls. Compared with controls, AN patients presented with relative bradycardia, more particularly during night periods but neither mean QT nor corrected mean QT length (calculated using Bazett formula) over the 24 hours of monitoring differed. However, QT/RR slope was found significantly enhanced compared with normals (-2.00 +/- 0.53 vs - 1.42 +/- 0.40) (P = 0.006): QT length related to heart rate was found longer for a heart rate <55 beats/min in AN. Mean 24-hours QT length appears unaltered in AN in the absence of electrolytic disorders. However, the QT/RR relationship was enhanced reflecting the specific autonomic imbalance encountered in this population. The clinical implications of such findings need to be discussed since an equivalent enhancement of QT/RR slope has been described after myocardial infarction in patients presenting life-threatening ventricular arrhythmias.

Adult↗
PubMed2004

Individual Interdependence between nocturnal ANS activity and performance in swimmers.

PURPOSE: Variations in autonomic nervous system activity (ANS) and variations in performances have been shown to be correlated at the group level in swimmers. The aim of the study was to investigate the strength of that relationship at the individual level. METHODS: Seven regional-level swimmers (four male, age 16.6 +/- 05 yr, 6.4 +/- 0.9 yr of practice) were included in the study. They performed maximal aerobic performance on a 400-m freestyle race before and after a 3-wk intensive training period, and following a 2-wk tapering period. ANS activity was assessed through heart rate variability (HRV) indices measured the night before each race and twice a week along the protocol. RESULTS: All HRV indices were altered, with global and parasympathetic indices decreasing from W1 to W3 in the whole group, while they increased until W5 in five swimmers, and continuously decreased in two. Best performances were respectively realized when global and parasympathetic indices of HRV were highest. Importantly, the relationship between the changes in performances and the changes in HRV indices was strong (DeltaPerf = -1.232 to 1.625.DeltaHF(wavelet), R(2) = 0.5); the greater the rebound in ANS activity after W3, the greater the performance improvement, and reciprocally. CONCLUSION: Performance is correlated with nocturnal ANS activity at an individual level. The decrease in ANS activity during intensive training is correlated with the loss in performance, and the rebound in ANS activity during tapering tracks with the gain in performance. Interestingly, the speed of the rebound during the tapering period was quite different between swimmers. ANS activity measurement may be useful to design and control individual training periods and to optimize the duration of tapering.

Adolescent↗
PubMed2003

Relationship among the severity of sleep apnea syndrome, cardiac arrhythmias, and autonomic imbalance.

The relationship between obstructive sleep apnea syndrome (OSAS), cardiac arrhythmias, and conduction disturbances in adults remains controversial. Early studies showed a higher prevalence than more recent and designed epidemiological studies. To clarify the actual prevalence of cardiac arrhythmias and conduction disturbances in patients referred for assessment of OSAS, a prospective cohort study was conducted: 147 consecutive patients (103 men; mean age of 54.5 +/- 10.7 years) underwent time-synchronized polysomnography and ECG Holter monitoring. OSAS was diagnosed in 66 (44.9%) of them based on an apnea hypopnea index (AHI) > or = 10. Prevalence of heart failure, of prior myocardial infarction, of hypertension, and of ventricular arrhythmias were similar in patients with or without OSAS. Nocturnal paroxysmal asystole was significantly more prevalent in OSAS patients (10.6 vs 1.2%; P < 0.02) and the number of episodes of bradycardia and pauses increased with the severity of the syndrome. Almost all bradycardic events occurred in patients with severe OSAS (AHI > 30), prolonged periods of arterial oxyhemoglobin desaturation, and low diurnal awake PaO2. Moreover, using heart rate variability analysis, nocturnal sinusal dysfunction contrasted with a blunted diurnal parasympathetic modulation of the sinus node. Frequent nocturnal nonsustained supraventricular tachycardias were predominantly found in patients with severe sleep related breathing disorders; however, an increased risk of ventricular arrhythmias was not found. Under continuous positive airway pressure treatment, the 1-year follow-up of OSAS patients with nocturnal pauses did not reveal any arrhythmic event justifying a specific intervention.

Arrhythmias, Cardiac↗
PubMed2003

Alteration of QT rate dependence reflects cardiac autonomic imbalance in patients with obstructive sleep apnea syndrome.

QT rate dependence is one of the major properties of ventricular repolarization with its circadian and autonomic modulations. The authors postulated that dynamic alterations in QT interval adaptation could help characterize patients with cardiac autonomic alterations, like those with obstructive sleep apnea syndrome (OSAS). To assess ventricular repolarization features in patients with OSAS, QT parameters and their dynamicity along RR intervals were compared from 24-hour ECG data of patients with and without this syndrome, assessing cardiac autonomic nervous system equilibrium by means of time-domain and frequency-domain analyses of heart rate variability (HRV). The study group consisted of 74 consecutive patients referred to the Sleep Laboratory for clinically suspected OSAS. The syndrome was confirmed in 30 (40.5%) patients according to standard polysomnographic criteria. QT length related to heart rate (HR) was found significantly shorter for HR < 70 beats/min in patients with OSAS(-1.32 +/- 0.35)compared with patients without OSAS(-1.99 +/- 0.40; P < 0.01). This flattened relationship was correlated with the severity of the sleep related disorder. Using multiple linear regression analysis, the apnea/hypopnea index and nocturnal normalized high frequencies (HFnu) were the most significant predictors of the QT/RR slope(R = 0.61; P < 0.0001). OSAS is significantly associated with a flattened relationship between QT duration and RR interval at low HRs. The alteration of cardiac parasympathetic tone occurring in severe OSAS patients may explain this altered rate dependent adaptation of myocardial repolarization.

Autonomic Nervous System↗
PubMed2002

Quantification of cumulated physical fatigue at the workplace.

Quantification of physical fatigue remains a challenge. We hypothesized that its effects on central autonomic nervous system activity could be explored for such a quantification. To test this relationship, we prospectively measured central autonomic nervous activity through nocturnal heart rate variability (HRV) in six French garbage collectors, aged 32.1+/-4.3 years, twice a week during 3 consecutive weeks of work, and during the following week of rest. Eight healthy sedentary males formed a control group. HRV indices were calculated by applying standard temporal domain and wavelet transform analyses to standard ECG recordings. During the 3 consecutive weeks of work, there was a significantly progressive decrease in HRV indices, particularly pNN50 (-34.2%, P<0.05), as well as the high (-33.3%, P<0.05) and low (-22.2%, P<0.01) frequency components of wavelet transform, while there was an increase, although non-significant, of the ratio of low to high frequencies (9.1%). During the resting period, there was a significant recovery of HRV indices, notably of its high (50.0%, P<0.05) and low (28.6%, P<0.05) frequency components. No such changes occurred in the control group. A central signature of cumulated physical fatigue can thus be detected and quantified through nocturnal autonomic nervous system activity. Its characteristics are those of a progressive parasympathetic withdrawal.

Adult↗
PubMed2002

High accuracy of automatic detection of atrial fibrillation using wavelet transform of heart rate intervals.

Permanent and paroxysmal AF is a risk factor for the occurrence and the recurrence of stroke, which can occur as its first manifestation. However, its automatic identification is still unsatisfactory. In this study, a new mathematical approach was evaluated to automate AF identification. A derivation set of 30 24-hour Holter recordings, 15 with chronic AF (CAF) and 15 with sinus rhythm (SR), allowed the authors to establish specific RR variability characteristics using wavelet and fractal analysis. Then, a validation set of 50 subjects was studied using these criteria, 19 with CAF, 16 with SR, and 15 with paroxysmal AF (PAF); and each QRS was classified as true or false sinus or AF beat. In the SR group, specificity reached 99.9%; in the CAF group, sensitivity reached 99.2%; in the PAF group, sensitivity reached 96.1%, and specificity 92.6%. However, classification on a patient basis provided a sensitivity of 100%. This new approach showed a high sensitivity and a high specificity for automatic AF detection, and could be used in screening for AF in large populations at risk.

Algorithms↗