Comparison of multiple cardiac signal acquisition technologies for heart rate variability analysis.

Heart rate variability analysis is a recognized non-invasive tool that is used to assess autonomic nervous system regulation in various clinical settings and medical conditions. A wide variety of HRV analysis methods have been proposed, but they all require a certain number of cardiac beats intervals. There are many ways to record cardiac activity: electrocardiography, phonocardiography, plethysmocardiography, seismocardiography. However, the feasibility of performing HRV analysis with these technologies and particularly their ability to detect autonomic nervous system changes still has to be studied. In this study, we developed a technology allowing the simultaneous monitoring of electrocardiography, phonocardiography, seismocardiography, photoplethysmocardiography and piezoplethysmocardiography and investigated whether these sensors could be used for HRV analysis. We therefore tested the evolution of several HRV parameters computed from several sensors before, during and after a postural change. The main findings of our study is that even if most sensors were suitable for mean HR computation, some of them demonstrated limited agreement for several HRV analyses methods. We also demonstrated that piezoplethysmocardiography showed better agreement with ECG than other sensors for most HRV indexes.

Prediction of hemodynamic reactivity using dynamic variations of Analgesia/Nociception Index (∆ANI).

The Analgesia/Nociception Index (ANI), a 0-100 non-invasive index calculated from heart rate variability, reflects the analgesia/nociception balance during general anesthesia. We hypothesized that dynamic variations of ANI (∆ANI) would provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. One hundred and twenty-eight patients undergoing ear-nose-throat or lower limb orthopedic surgery were analyzed in this prospective observational study. The ANI, heart rate and systolic blood pressure were recorded before induction, at skin incision, during procedure and at emergence from general anesthesia. Changes in these variables were recorded after 1 min for ANI (ANI1min) and 5 min for heart rate and systolic blood pressure. The dynamic variation of ANI at the different time points was defined as: ∆ANI = (ANI1min - ANI)/([ANI + ANI1min]/2). Receiver-operating characteristic (ROC) curves were built to evaluate the performance of ANI, ANI1 min and ∆ANI to predict hemodynamic reactivity (increase by more than 20 % in heart rate and/or systolic blood pressure within 5 min). For the prediction of hemodynamic reactivity, better performance was observed with ∆ANI (area under ROC curve (AUC ROC) = 0.90) in comparison to ANI (ROC AUC = 0.50) and ANI1min (ROC AUC = 0.77). A ∆ANI threshold of -19 % predicts hemodynamic reactivity with 85 % [95 % CI 77-91] sensitivity and 85 % [95 % CI 81-89] specificity. Dynamic variations of ANI provide better performance than static values to predict hemodynamic reactivity during desflurane/remifentanil general anesthesia. These findings may be of interest for the individual adaptation of remifentanil doses guided by ∆ANI during general anesthesia, although this remains to be demonstrated.

Variations of the analgesia nociception index during general anaesthesia for laparoscopic abdominal surgery.

The analgesia nociception index (ANI) is an online heart rate variability analysis proposed for assessment of the antinociception/nociception balance. In this observational study, we compared ANI with heart rate (HR) and systolic blood pressure (SBP) during various noxious stimuli in anaesthetized patients. 15 adult patients undergoing laparoscopic appendectomy or cholecystectomy were studied. Patients received target controlled infusions of propofol (adjusted to maintain the Bispectral index in the range [40-60]) and remifentanil (with target increase in case of haemodynamic reactivity [increase in HR and/or SBP >20% of baseline]), and cisatracurium. Medical staff was blind to the ANI monitor. ANI and haemodynamic data were recorded at predefined times before and during surgery, including tetanic stimulation of the ulnar nerve before start of surgery. Anaesthesia induction decreased HR and SBP, while high ANI values (88 [17]) were recorded, indicating parasympathetic predominance. In 10 out of 11 patients, tetanic stimulation led to a transient (<5 min) decrease in ANI to 48 (40) whereas HR and SBP did not change. After start of surgery, ANI decreased to 60 (39) and decreased further to 50 (15) after the pneumoperitoneum was inflated, while there was no significant change in HR or SBP. When haemodynamic reactivity occurred, ANI had further decreased to 40 (15). After completion of surgery, ANI returned to 90 (34). ANI seems more sensitive than HR and SBP to moderate nociceptive stimuli in propofol-anaesthetized patients. Whether ANI monitoring may allow preventing haemodynamic reactivity to noxious stimuli remains to be demonstrated.

[Heart rate variability. Applications in psychiatry]. / La variabilité de la fréquence cardiaque. Intérêts en psychiatrie.

BACKGROUND: The autonomic nervous system sends messages through the sympathetic and parasympathetic nervous system. The sympathetic nervous system innervates the cardioaccelerating center of the heart, the lungs (increased ventilatory rhythm and dilatation of the bronchi) and the non-striated muscles (artery contraction). It releases adrenaline and noradrenaline. As opposed to the sympathetic nervous system, it innervates the cardiomoderator center of the heart, the lungs (slower ventilatory rhythm and contraction of the bronchi) and the non-striated muscles (artery dilatation). It uses acetylcholine (ACh) as its neurotransmitter. Sympathetic and parasympathetic divisions function antagonistically to preserve a dynamic modulation of vital functions. These systems act on the heart respectively through the stellar ganglion and the vagus nerve. The interaction of these messages towards the sinoauricular node is responsible for normal cardiac variability, which can be measured by monitoring heart rate variability (HRV). Heart rate is primarily controlled by vagal activity. Sensorial data coming from the heart are fed back to the central nervous system. HRV is an indicator of both how the central nervous system regulates the autonomic nervous system, and of how peripheral neurons feed information back to the central level. HRV measures are derived by estimating the variation among a set of temporally ordered interbeat intervals. The state of perfect symmetry, which, in medical parlance, is called respiratory sinus arrhythmia (RSA), can be described as a state of cardiac coherence. Obtaining a series of interbeat intervals requires a continuous measure of heart rate, typically electrocardiography (ECG). Commercially available software is then used to define the interbeat intervals within an ECG recording. LITERATURE FINDINGS: The autonomic nervous system is highly adaptable and allows the organism to maintain its balance when experiencing strain or stress. Conversely, a lack of flexibility and a rigid system can lead to somatic and psychological pathologies. Several studies have shown a link between reduced HRV in postmyocardial infarction patients and increased risk for adverse cardiovascular events, including ventricular arrhythmias and sudden death. Recently, studies indicate that patients with depression and anxiety disorders exhibit abnormally low HRV compared with non-psychiatric controls. Reduced HRV seems indicate decreased cardiac vagal tone and elevated sympathetic activity in anxious and depressive patients and would reflect deficit in flexibility of emotional physiological mechanisms. A few studies have also revealed that biofeedback using respiratory control, relaxation and meditation techniques can increase HRV. For now, there is insufficient data to determine if paced respiration or subjective relaxation is necessary or sufficient for the efficacy of HRV biofeedback. Although the literature is modest, this review suggests that the use of biofeedback with relaxation and meditation approaches may result in increased HRV and parasympathetic activity. Limitations of the review literature have also been considered to identify areas for future research.

Influence of averaged fetal heart rate in heart rate variability analysis.

In high-income countries, fetal hypoxia affects 3 to 8 newborns per 1000 live births with subsequent moderate or severe Hypoxic-Ischemic Encephalopathy (HIE) in 0.5 to 1 per 1000 live births. Visual interpretation of FHR signal issued from a Doppler ultrasound cardiotocography is the gold standard to monitor fetal condition. Unfortunately, its analysis presents a high rate of inter-observer variability and a low specificity to predict poor neonatal outcomes. Under hypoxia, the fetus develops several adaptive mechanisms regulated by the autonomic nervous system inducing changes in the fetal heart rate variability. Though fetal heart rate variability methods demonstrated abilities to predict perinatal asphyxia, most of the Doppler ultrasound technologies used in clinical practice do not provide sufficiently accurate fetal heart rate signals for heart rate variability analysis. Indeed, Doppler ultrasound cardiotocography usually provides fetal heart rate values averaged over 2 or 3 beats which can constitute a limitation for spectral analysis. We developed a fetal heart rate variability analysis method: the Fetal Stress Index (FSI). The objective of this study was to investigate the influence of averaged fetal heart rate on this new index in order to check the feasibility of computing the FSI from the signal issued from Doppler ultrasound cardiotocography.

AcCorps: A low-cost 3D printed stethoscope for fetal phonocardiography.

The analysis of fetal heart rate provides valuable information regarding the fetus wellbeing. Fetal phonocardiography is a low-cost and passive method allowing the acquisition of fetal heart rate by recording acoustic vibrations on the mother's abdomen. However, most of available stethoscopes are not optimized for a robust acquisition of fetal heart sound. In this publication, we investigated a new design of low-cost and 3D printed stethoscope. This device was optimized to provide an acoustic amplification especially in the low-frequency band which corresponds to the fetal heart sounds. This device was tested i) in silico, ii) on a test bench and iii) on 5 pregnant volunteers.

Influence of Wilson Ce nter Terminal on fetal electrocardiography acquisition.

The acquisition of a standard 10-leads electrocardiography (ECG) is performed using the Wilson Center Terminal (WCT) reference with a normalized electrode positioning. However, in the case of non-invasive fetal ECG (fECG) acquisition, there is no standardization on the positioning of the electrodes on the abdomen and many authors suggest an acquisition with or without a WCT. The use of the WCT for the acquisition of the fetal heart rate (FHR) is not justified. The objective of this paper is to quantify the influence of this reference compared to a direct measurement. For this purpose, we developed a device allowing the acquisition of the fECG and compared the two configurations on 6 volunteer pregnants. The noise levels and the fetal QRS morphology were compared, showing no superiority of the WCT acquisition compared to a direct differential measurement.

Closed-loop administration of analgesic drugs based on heart rate variability analysis.

General anesthesia is based on the use of hypnotic, muscle relaxant and analgesic drugs in order to render the patient unresponsive to the surgical procedure. The difficulty for anesthesiologists is then to determinate the minimum efficient dose to avoid any risk of under or over dosing. For several years, monitoring systems were developed in order to measure depth of hypnosis, myorelaxation and analgesia. As soon as all these monitoring systems became available, several teams worked on the closed-loop administration of anesthetic agents. We have developed a closed-loop system allowing the automatic administration of analgesic drugs. This system is based on the analysis of a heart rate variability based index: the ANI (Analgesia Nociception Index). In this paper, we describe this device and demonstrate its efficiency, repeatability and safety in a simulation environment.

A new analysis of heart rate variability in the assessment of fetal parasympathetic activity: An experimental study in a fetal sheep model.

Analysis of heart rate variability (HRV) is a recognized tool in the assessment of autonomic nervous system (ANS) activity. Indeed, both time and spectral analysis techniques enable us to obtain indexes that are related to the way the ANS regulates the heart rate. However, these techniques are limited in terms of the lack of thresholds of the numerical indexes, which is primarily due to high inter-subject variability. We proposed a new fetal HRV analysis method related to the parasympathetic activity of the ANS. The aim of this study was to evaluate the performance of our method compared to commonly used HRV analysis, with regard to i) the ability to detect changes in ANS activity and ii) inter-subject variability. This study was performed in seven sheep fetuses. In order to evaluate the sensitivity and specificity of our index in evaluating parasympathetic activity, we directly administered 2.5 mg intravenous atropine, to inhibit parasympathetic tone, and 5 mg propranolol to block sympathetic activity. Our index, as well as time analysis (root mean square of the successive differences; RMSSD) and spectral analysis (high frequency (HF) and low frequency (LF) spectral components obtained via fast Fourier transform), were measured before and after injection. Inter-subject variability was estimated by the coefficient of variance (%CV). In order to evaluate the ability of HRV parameters to detect fetal parasympathetic decrease, we also estimated the effect size for each HRV parameter before and after injections. As expected, our index, the HF spectral component, and the RMSSD were reduced after the atropine injection. Moreover, our index presented a higher effect size. The %CV was far lower for our index than for RMSSD, HF, and LF. Although LF decreased after propranolol administration, fetal stress index, RMSSD, and HF were not significantly different, confirming the fact that those indexes are specific to the parasympathetic nervous system. In conclusion, our method appeared to be effective in detecting parasympathetic inhibition. Moreover, inter-subject variability was much lower, and effect size higher, with our method compared to other HRV analysis methods.

Influence of ECG sampling rate in fetal heart rate variability analysis.

Fetal hypoxia results in a fetal blood acidosis (pH<;7.10). In such a situation, the fetus develops several adaptation mechanisms regulated by the autonomic nervous system. Many studies demonstrated significant changes in heart rate variability in hypoxic fetuses. So, fetal heart rate variability analysis could be of precious help for fetal hypoxia prediction. Commonly used fetal heart rate variability analysis methods have been shown to be sensitive to the ECG signal sampling rate. Indeed, a low sampling rate could induce variability in the heart beat detection which will alter the heart rate variability estimation. In this paper, we introduce an original fetal heart rate variability analysis method. We hypothesize that this method will be less sensitive to ECG sampling frequency changes than common heart rate variability analysis methods. We then compared the results of this new heart rate variability analysis method with two different sampling frequencies (250-1000 Hz).

Evaluation of the clinical benefit of an electromagnetic navigation system for CT-guided interventional radiology procedures in the thoraco-abdominal region compared with conventional CT guidance (CTNAV II): study protocol for a randomised controlled trial.

BACKGROUND: Interventional radiology includes a range of minimally invasive image-guided diagnostic and therapeutic procedures that have become routine clinical practice. Each procedure involves a percutaneous needle insertion, often guided using computed tomography (CT) because of its availability and usability. However, procedures remain complicated, in particular when an obstacle must be avoided, meaning that an oblique trajectory is required. Navigation systems track the operator's instruments, meaning the position and progression of the instruments are visualised in real time on the patient's images. A novel electromagnetic navigation system for CT-guided interventional procedures (IMACTIS-CT®) has been developed, and a previous clinical trial demonstrated improved needle placement accuracy in navigation-assisted procedures. In the present trial, we are evaluating the clinical benefit of the navigation system during the needle insertion step of CT-guided procedures in the thoraco-abdominal region. METHODS/DESIGN: This study is designed as an open, multicentre, prospective, randomised, controlled interventional clinical trial and is structured as a standard two-arm, parallel-design, individually randomised trial. A maximum of 500 patients will be enrolled. In the experimental arm (navigation system), the procedures are carried out using navigation assistance, and in the active comparator arm (CT), the procedures are carried out with conventional CT guidance. The randomisation is stratified by centre and by the expected difficulty of the procedure. The primary outcome of the trial is a combined criterion to assess the safety (number of serious adverse events), efficacy (number of targets reached) and performance (number of control scans acquired) of navigation-assisted, CT-guided procedures as evaluated by a blinded radiologist and confirmed by an expert committee in case of discordance. The secondary outcomes are (1) the duration of the procedure, (2) the satisfaction of the operator and (3) the irradiation dose delivered, with (4) subgroup analysis according to the expected difficulty of the procedure, as well as an evaluation of (5) the usability of the device. DISCUSSION: This trial addresses the lack of published high-level evidence studies in which navigation-assisted CT-guided interventional procedures are evaluated. This trial is important because it addresses the problems associated with conventional CT guidance and is particularly relevant because the number of interventional radiology procedures carried out in routine clinical practice is increasing. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01896219 . Registered on 5 July 2013.

Comparison of pulse rate variability and heart rate variability for high frequency content estimation.

Heart Rate Variability (HRV) analysis can be of precious help in most of clinical situations because it is able to quantify the Autonomic Nervous System (ANS) activity. The HRV high frequency (HF) content, related to the parasympathetic tone, reflects the ANS response to an external stimulus responsible of pain, stress or various emotions. We have previously developed the Analgesia Nociception Index (ANI), based on HRV high frequency content estimation, which quantifies continuously the vagal tone in order to guide analgesic drug administration during general anesthesia. This technology has been largely validated during the peri-operative period. Currently, ANI is obtained from a specific algorithm analyzing a time series representing successive heart periods measured on the electrocardiographic (ECG) signal. In the perspective of widening the application fields of this technology, in particular for homecare monitoring, it has become necessary to simplify signal acquisition by using e.g. a pulse plethysmographic (PPG) sensor. Even if Pulse Rate Variability (PRV) analysis issued from PPG sensors has been shown to be unreliable and a bad predictor of HRV analysis results, we have compared PRV and HRV both estimated by ANI as well as HF and HF/(HF+LF) spectral analysis on both signals.

Optimization of extra corporeal enteral prosthesis (ECEP) by selective aspiration of the digestive flow.

Reinfusion is a medical process which collects digestive flow from a proximal stoma to a distal one, in patient who had a post-operative double enteral stoma. This process avoids the risk of under nutrition and frees the patient from a Total Parenteral Nutrition to offset the digestive loss. Most of the previous ways of reinfusion first collect the digestive flow into a bag before instillation. We developed an ambulatory reinfusion pump (ECEP) which had the advantage to collect the digestive flow directly from the proximal stoma and to pump it to the distal one. However, the main risk of such a continuous pumping process is to create mucosae lesions by direct suction. The aim of this study is to up-grade our device by introducing a selective aspiration based on the arrival of digestive flow.

Performance evaluation of the extra corporeal enteral prosthesis (ECEP) vs a By-Pass.

Intestinal stoma constitutes a symptomatic treatment in a wide range of digestive diseases, such as rectal cancer, digestive traumatic perforation and inflammatory intestinal diseases. It affects a patient's life causing physiologic and social constraints. The stoma can lead to involution of the downstream digestive tissue, impairing his function in case of restored continuity. Some technical solutions have been developed in order to maintain intestinal continuity, reduce inflammatory risk and to increase patient's quality of life. In this paper, we describe a smart intestinal prosthesis equipped with a pump working as an intestinal segment and creating a bypass between the upstream and downstream intestinal sides. We also evaluate the performance the digestive prosthesis ECEP vs a simple digestive By-Pass.

Physiological Signal Processing for Individualized Anti-nociception Management During General Anesthesia: a Review.

OBJECTIVE: The aim of this paper is to review existing technologies for the nociception / anti-nociception balance evaluation during surgery under general anesthesia. METHODS: General anesthesia combines the use of analgesic, hypnotic and muscle-relaxant drugs in order to obtain a correct level of patient non-responsiveness during surgery. During the last decade, great efforts have been deployed in order to find adequate ways to measure how anesthetic drugs affect a patient's response to surgical nociception. Nowadays, though some monitoring devices allow obtaining information about hypnosis and muscle relaxation, no gold standard exists for the nociception / anti-nociception balance evaluation. Articles from the PubMed literature search engine were reviewed. As this paper focused on surgery under general anesthesia, articles about nociception monitoring on conscious patients, in post-anesthesia care unit or in intensive care unit were not considered. RESULTS: In this article, we present a review of existing technologies for the nociception / anti-nociception balance evaluation, which is based in all cases on the analysis of the autonomous nervous system activity. Presented systems, based on sensors and physiological signals processing algorithms, allow studying the patients' reaction regarding anesthesia and surgery. CONCLUSION: Some technological solutions for nociception / antinociception balance monitoring were described. Though presented devices could constitute efficient solutions for individualized anti-nociception management during general anesthesia, this review of current literature emphasizes the fact that the choice to use one or the other mainly relies on the clinical context and the general purpose of the monitoring.

Comparison of four methods for measuring elevation of FRC in mechanically ventilated infants.

The aim of the study was to compare measurements of the elevation of functional residual capacity (FRC) above the relaxation volume obtained in 34 mechanically ventilated infants (median weight 2.6 kg, range 1.2-9) from four different methods: (1) direct measurement of the complete exhalation volume after brief disconnection from the ventilator, (2) calculated measurement from total positive end-expiratory pressure (PEEP) measured by end-expiratory occlusion of the breathing circuit, (3) extrapolated evaluation from the mathematical model of Brody, (4) extrapolated evaluation from the passive expiration method. We considered the direct measurement (1) as the "gold standard". Measurements obtained by total PEEP (2) and by the Brody's mathematical model (3) provided similar results than the direct measurement. Conversely, graphical extrapolation from the passive expiration method (4) underestimated the elevation of FRC. In conclusion, we suggest using the mathematical extrapolation from the Brody's model to evaluate the elevation of FRC in mechanically ventilated infants: this method is non-invasive, does not require disruption of gas flow, can be easily performed with all the neonatal ventilators, and allows continuous breath-by-breath measurements.

Measurement of respiratory mechanics in paediatric intensive care: in vitro assessment of a pulmonary function device.

OBJECTIVE: To evaluate a recently developed and manufactured device for monitoring respiratory parameters in mechanically ventilated children. DESIGN: In vitro study using a lung model. SETTING: University paediatric intensive care unit. MATERIAL AND INTERVENTIONS: Evaluation of the accuracy of volume and pressure measurements, of the determination of respiratory system compliance (10 to 30 ml/cmH2O) and of resistance (20 and 50 cmH2O/l per s) by the inflation technique (volume- and pressure-controlled mode of ventilation); assessment of interobserver agreement for compliance (10, 15 ml/cmH2O) and resistance (20, 50 cmH2O/l per s) determinations (ANOVA, intraclass correlation coefficient). MEASUREMENTS AND RESULTS: The accuracy of volume measurements (No.1 Fleisch pneumotachograph) was < or = 5 % of true volumes up to 11 (Flow: 30 l/min) even after the introduction of an endotracheal tube. The accuracy of pressure measurements up to 70 cmH2O was < or = 2.5% of the true values. Coefficients of variation of volume and pressure measurements were < 2%. The accuracy of compliance and resistance determinations was, respectively, < or = 17 and 25% of the true values. No significant observer effect was found on compliance and resistance determinations. Indeed, mean differences in compliance and resistance determinations by pairs of observers were < 1%. Intraclass correlation coefficients were > 0.98. CONCLUSIONS: The measuring error of volume, pressure, compliance and resistance determined using this monitoring system seems acceptable for monitoring purpose. Moreover, use of this system by members of the medical team can be recommended since results obtained by observers, even untrained ones, were similar. In vivo evaluation is now needed.

A new application of an old method for respiratory mechanics measurements: the passive inflation method in newborn infants during pressure-controlled ventilation.

We have previously described a passive inflation method during constant inspiratory flow for measuring total respiratory elastance and resistance during mechanical ventilation in newborns. The simple method for measuring respiratory mechanics had been assessed during decelerating inspiratory flow obtained with pressure controlled ventilation (PCV). We report an application of this method to preterm and full-term mechanically ventilated newborn infants and a comparison with the occlusion method. Twenty-one newborn infants (birth weight 1,060 to 3,650 g; gestational age 26 to 41 weeks), between 1 to 55 days of postnatal age, were enrolled in the study. They were ventilated with a "Servo ventilator 900C," first set in the pressure-controlled mode and then in the volume-controlled mode without changing the tidal volume (VT), inspiratory time or ventilator rate. Flow was measured through a pneumotachograph inserted between the endotracheal tube (ETT) and the breathing circuit; VT was obtained by integration of flow and airway pressure measured directly at the airway opening. Flow, volume, and pressure were plotted on analog X/Y tables to obtain pressure-volume (P/V) and flow-volume (V/V) loops, as well as pressure-time curves. Occlusion was performed by using the end-inspiratory and the end-expiratory pause buttons of the ventilator. The passive inflation method during PCV was based on the analysis of P/V and V/V loops and provided compliance (Crs(PC)infl.), resistance Rrs(PC)infl.) of the respiratory system, and intrinsic positive end-expiratory pressure (PEEP(PC)i,infl.). These values were compared with (1) compliance (Crs(PC)occl.) and intrinsic positive end-expiratory pressure (PEEP(PC)i,occl.) measured by the occlusion method during PCV; (2) static (Crs(VC),occl.) and dynamic (Crs(VC),dyn.) compliance, airway (R(aw)(VC),), tissue (Rrs(VC),visc.) and total resistance (Rrs(VC),occl.), and intrinsic positive end-expiratory pressure (PEEP(VC)i,occl.) measured by the occlusion method during volume-controlled ventilation. Crs(PC),infl. correlated well with Crs(PC),occl., Crs(VC),occl., and Crs(VC),dyn.. Furthermore, Crs(PC),infl. and Crs(VC),dyn. did not differ significantly. Rrs(PC),infl. correlated well and did not differ significantly from total inspiratory resistance, i.e., the sum of R(aw)(VC) and Rrs(VC),vis. PEEPPC,i,infl. correlated well and did not differ significantly from PEEP(PC)i.occl. and from PEEP(VC),i,occl. The passive inflation method can be used during PCV with a decelerating flow waveform. It provides dynamic compliance, inspiratory resistance of the respiratory system, and intrinsic PEEP from the analysis of V/V and P/V loops recorded at the airway opening. This technique is simple to use and well tolerated by preterm and full-term ventilated newborn infants. It can be a good alternative to occlusion methods.

[Value of mapping in surgical treatment of ventricular tachycardia]. / Utilité de la cartographie dans la chirurgie des tachycardies ventriculaires.

Surgery may be proposed for patients with a localised aneurysm or akinesia for treatment of monomorphic ventricular tachycardia resistant to antiarrhythmic therapy after myocardial infarction. The multiplicity of tachycardia forms in the same patient, the variability of their mechanism which is not necessarily limited to the subendocardia layers, require mapping to guide the surgeon in the destruction of the anatomical substrates. In a series of 57 ventricular tachycardias recorded in 17 patients with myocardial infarction the authors demonstrated that a system of computerised mapping of the epicardial and endocardial regions optimised the results of this form of surgery. Mapping localised, sometimes at a distance from the scar, classical subendocardial reentry, implicated on occasion the mitral papillary muscle in the mechanism or a tachycardia in cases of inferior or lateral infarction and localised the reentry in the epicardium of the lower layers of the septum. The identification of these "atypical" mechanisms significantly improves the number of patients without inducible arrhythmias after surgery (from 50 to 87% in the authors' experience), without changing the operative mortality. The only really curative approach because of the limitations of catheter ablation, this surgery is a complementary method to implantable defibrillators in the management of post-infarction ventricular tachycardia.

[Automatic implantable defibrillator and antiarrhythmic surgery in ischemic cardiopathies. Apropos of 53 cases]. / Le défibrillateur automatique implantable et la chirurgie antiarythmique dans les cardiopathies ischémiques. A propos de 53 observations.

The automatic implantable defibrillator (AID) and antiarrhythmic surgery are the two therapeutic options after failure of catheter ablation and/or antiarrhythmic therapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with coronary artery disease. The authors undertook retrospective study of the characteristics of two groups of patients treated between November 31st 1987 et December 31st 1993 either by AID (28 men and 4 women with an average age of: 56.1 +/- 11.2 years) or by surgery (19 men and 2 women with an average age of: 60.6 +/- 6.8 years). The "surgical" patients differed from "defibrillator" patients in the fewer number of cardiac arrests, a higher proportion of sustained monomorphic VT, better tolerated sustained monomorphic VT (rarely syncopal), fewer early post-infarction arrythmias (< or = 8 weeks), more anterior wall infarction and a higher proportion of aneuvrysms. The perioperative mortality was 6.2% in the "defibrillator" group and nil in the "surgical" group (p = NS). At 2 years, the sudden death rate in the "defibrillator" and "surgical" groups was 7.5% and 0% respectively and total cardiac mortality was 17% and 20% respectively (p = NS). The authors conclude that perioperative mortality and the sudden death rate at 2 years are relatively low in the two groups. However, the total cardiac mortality remains high, largely related to perioperative death and secondary cardiac failure. Nevertheless, compared with defibrillator patients and with identical average ejection fractions, there was no extra mortality due to cardiac failure after antiarrhythmic surgery.