Use of an automated external defibrillator: a prospective observational study of first-year medical students.

UNLABELLED: This study evaluated the ability of young adults to respond to a simulated cardiac arrest using an automated external defibrillator (AED). METHOD: The study population was first-year medical students. None had received their mandatory training in emergency medicine. They role-played in pairs and entered a room in which a third person was lying on the floor and simulating unconsciousness and respiratory arrest. An AED and the corresponding poster-format instructions were clearly visible in the room, next to a telephone. The actions of pairs of responders were recorded. RESULTS: Interpretable results were obtained for 90 pairs of subjects. Most (96%) assessed vital signs and 20% performed this assessment correctly. Chest compressions were performed by 57%, 71% called emergency services, 4.5% removed the AED from the wall (but only one pair used it) and 8.9% did nothing. For 41% of the pairs, at least one member already had a cardiopulmonary resuscitation (CPR) certificate. The only statistically significant difference between students with and without a CPR certificate concerned use of the telephone to call emergency services. DISCUSSION: Despite the presence of an AED next to the telephone, the defibrillator was almost never used by the participants. Four out of ten pairs did not start chest compressions. The absence of any significant differences in performance between students with and without a CPR certificate casts doubt on the efficacy of the CPR training they had received. CONCLUSION: Results indicate the need for greater awareness of how to deal with cardiac arrest and the use of an AED when one is available.

[Pheochromocytoma and cardiogenic failure: an indication for emergency adrenalectomy]. / Phéochromocytome et défaillance cardiaque : une indication exceptionnelle de surrénalectomie en urgence ou semi-urgence.

OBJECTIVE: To identify cardiogenic failure or cardiogenic shock associated with pheochromocytoma diagnosis and emergency adrenalectomy. Update this unusual presentation of pheochromocytoma. METHODS: Between 1998 and 2009, 119 adrenalectomies were performed in our department, among which 19 cases for pheochromocytoma. We reported three cases with cardiogenic failure or cardiogenic shock associated with emergency adrenalectomy. RESULTS: Patients were 36, 41 and 67 years old. The elapsed time between cardiogenic failure and surgery was 0, 7 and 19 days. The first diagnosis was a viral myocarditis in those three cases. The diagnosis of adrenal pheochromocytoma was done in a second step by the association of adrenal tumour on abdominal CT scan and detection of significantly elevated plasma/urine catecholamine. Severe systolic dysfunction with low ejection fraction was associated in all cases. Cardiac function was quickly restored after adrenalectomy. CONCLUSION: Cardiac emergency associated with pheochromocytoma is an unusual clinical presentation. When diagnosis fails to be performed, patients have a very poor prognosis. According to a review of the sparse literature, only early recognition and emergency adrenalectomy can improve the outcome.

Changes in local and distant EEG activities before, during and after the observation and execution of sequential finger movements.

AIM OF THE STUDY: To consider cortical oscillations at local and distant/large scale levels during the time course of motor events under both an observation and an execution condition. METHODS: Local and distant changes in EEG cortical oscillations were respectively assessed by the Event-Related Desynchronization/Synchronization technique and the Synchronization Likelihood technique. Data collected prior to, during, and after observation and execution of complex sequential finger movements were used to investigate these changes. EEGs were recorded from 19 active sites across the cortex of 10 subjects. Sensorimotor activity was examined in alpha frequency bands. RESULTS: Local power changes and global interregional synchronizations were two distinct phenomena, which occurred simultaneously and displayed different spatiotemporal patterns. DISCUSSION AND CONCLUSIONS: These findings demonstrate the complementary character of both analysis techniques. Results are discussed in light of the recent findings from the cognitive and behavioural neuroscience literature.

Cryoablation of junctional tachycardia at high risk of atrio-ventricular block.

INTRODUCTION: Transcatheter cryoablation is an alternative option for the treatment of supraventricular tachycardia, due to its very low risk of permanent atrio-ventricular block. However, the overcost of cryocatheter and the high recurrence rate of this emerging technology braked its large use. This study reports the results of an approach using cryoablation for the treatment of junctional tachycardia (JT) in selected patients at high risk of atrio-ventricular (AV) block. PATIENTS AND METHODS: Out of a series of 199 patients with JT treated by catheter ablation, 26 benefited from cryoablation (mean age 32.8+/-15 years, 15 males). The indications were the presence of an accessory pathway with a high risk of atrio-ventricular block (n=7), a slow pathway difficult to ablate, with a risk of atrio-ventricular block (n=7), a recurrence after a RF procedure, during which a transient atrio-ventricular block has occurred (n=4), and finally patients at young age (n=8). RESULTS: The primary success rate was 92%. No permanent AV block has been reported, neither with RF nor with cryoablation. The recurrence rate at 9+/-10 months was at 29% after cryoablation and 8.6% after RF. In case of AV nodal reentrant tachycardia, the additional cost of cryotherapy catheter has been avoided in 76.85% of cases. The use of a cryotherapy catheter and RF catheter has been necessary for the remaining cases. CONCLUSION: This study demonstrates that an approach, reserving cryoablation in selected patients at high risk of AV block is an alternative strategy to "the systematic use" of cryotherapy in the ablation of JT with a high efficacy, an excellent safety and a reduced cost.

Electron beam treatment verification using measured and Monte Carlo predicted portal images.

Electron beam treatments may benefit from techniques to verify patient positioning and dose delivery. This is particularly so for complex techniques such as mixed photon and electron beam radiotherapy and electron beam modulated therapy. This study demonstrates that it is possible to use the bremsstrahlung photons in an electron beam from a dual scattering foil linear accelerator to obtain portal images of electron beam treatments. The possibility of using Monte Carlo (MC) simulations to predict the electron beam treatment portal images was explored. The MC code EGSnrc was used to model a Varian CL21EX linear accelerator (linac) and to characterize the bremsstrahlung photon production in the linac head. It was found that the main sources of photons in the electron beam are the scattering foils, the applicator and the beam-shaping cut-out. Images were acquired using the Varian CL21EX linac and the Varian aS500 electronic portal imager (EPI); four electron energies (6, 9, 12, 16 MeV), and different applicator and cut-out sizes were used. It was possible to acquire images with as little as 10.7 MU per image. The contrast, the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), the resolution and an estimate of the modulated transfer function (MTF) of the electron beam portal images were computed using a quality assurance (QA) phantom and were found to be comparable to those of a 6 MV photon beam. Images were also acquired using a Rando anthropomorphic phantom. MC simulations were used to model the aS500 EPID and to obtain predicted portal images of the QA and Rando phantom. The contrast in simulated and measured portal images agrees within +/-5% for both the QA and the Rando phantom. The measured and simulated images allow for a verification of the phantom positioning by making sure that the structure edges are well aligned. This study suggests that the Varian aS500 portal imager can be used to obtain patient portal images of electron beams in the scattering foil linacs.

[Prevention of recurrent amiodarone-induced hyperthyroidism by iodine-131]. / Prévention des récidives d'hyperthyroïdie a l'amiodarone par l'iode131.

Amioradone-induced hyperthyroidism is a common complication of amiodarone therapy. Although definitive interruption of amiodarone is recommended because of the risks of aggravation of the arrhythmias, some patients may require the reintroduction of amiodarone several months after normalisation of thyroid function. The authors undertook a retrospective study of the effects of preventive treatment of recurrences of amiodarone-induced hyperthyroidism with I131. The indication of amiodarone therapy was recurrent, symptomatic, paroxysmal atrial fibrillation in 13 cases and ventricular tachycardia in 5 cases (M = 14, average age 64 +/- 13 years). The underlying cardiac disease was dilated cardiomyopathy (N = 5), ischaemic heart disease (N = 3), hypertensive heart disease (N = 2), arrhythmogenic right ventricular dysplasia (N = 2) or valvular heart disease (N = 2). Two patients had idiopathic atrial fibrillation. An average dose of 576 +/- 184 MBq of I131 was administered 34 +/- 37 months after an episode of amiodarone-induced hyperthyroidism. Amiodarone was reintroduced in 16 of the 18 patients after a treatment-free period of 98 +/- 262 days. Transient post-radioiodine hyperthyroidism was observed in 3 cases (17%). Sixteen patients (89%) developed hypothyroidism requiring replacement therapy with L-thyroxine. There were no recurrences of amiodarone-induced hyperthyroidism. After 24 +/- 17 months follow-up, the arrhythmias were controlled in 13 of the 16 patients (81%) who underwent the whole treatment sequence. The authors conclude that preventive treatment with I131 is an effective alternative to prevent recurrence of amiodarone-induced hyperthyroidism in patients requiring reintroduction of amiodarone to control their arrhythmias.

A Monte Carlo-based method to estimate radiation dose from spiral CT: from phantom testing to patient-specific models.

The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and voxelized patient data. To accomplish this we have modified a general purpose Monte Carlo transport code (MCNP4B) to simulate the CT x-ray source and movement, and then to calculate absorbed radiation dose in desired objects. The movement of the source in either axial or spiral modes was modelled explicitly while the CT system components were modelled using published information about x-ray spectra as well as information provided by the manufacturer. Simulations were performed for single axial scans using the head and body computed tomography dose index (CTDI) polymethylmethacrylate phantoms at both central and peripheral positions for all available beam energies and slice thicknesses. For comparison, corresponding physical measurements of CTDI in phantom were made with an ion chamber. To obtain absolute dose values, simulations and measurements were performed in air at the scanner isocentre for each beam energy. To extend the verification, the CT scanner model was applied to the MIRD V model and compared with published results using similar technical factors. After verification of the model, the generalized source was simulated and applied to voxelized models of patient anatomy. The simulated and measured absolute dose data in phantom agreed to within 2% for the head phantom and within 4% for the body phantom at 120 and 140 kVp; this extends to 8% for the head and 9% for the body phantom across all available beam energies and positions. For the head phantom, the simulated and measured absolute dose data agree to within 2% across all slice thicknesses at 120 kVp. Our results in the MIRD phantom agree within 11% of all the different organ dose values published by the UK's ImPACT group for a scan using an equivalent scanner, kVp, collimation, pitch and mAs. The CT source model was shown to calculate both a relative and absolute radiation dose distribution throughout the entire volume in a patient-specific matrix geometry. Results of initial testing are promising and application to patient models was shown to be feasible.

Intimo-intimal intussusception: a rare clinical form of aortic dissection.

A 33-year-old hypertensive man presented with epigastric pain radiating to the back. Transoesophageal echocardiography (TOE) revealed an intimal flap on the aortic arch and descending aorta. No intimal flap of the ascending aorta was detected on TOE or CT. The diagnosis was made on opening the ascending aorta: complete circumferential dissection of the ascending aorta flush with the coronary ostia, with no residual intimal flap, and intimo-intimal glove-finger intussusception of the internal channel into the descending thoracic aorta. Aortic intussusception is a very rare form of Type I dissection, and the absence of intimal tear in the ascending aorta can be misleading and delay the diagnosis.

Clinical application of laser evoked potentials using the Nd:YAG laser.

The clinical interest of a new type of laser evoked potentials (LEPs) using Nd:YAG laser was assessed in the diagnosis of peripheral neuropathies affecting the small-diameter nerve fibres, and of spinal cord lesions, affecting the spinothalamic tract. Twelve patients aged from 26 to 79 years with sensory neuropathies (n = 6) or spinal cord lesions (n = 6) underwent neurophysiological examination of the lower limbs comprising quantitative sensory testing, i.e., the determination of vibratory and thermal thresholds (VT and TT), somatosensory evoked potentials (SEPs) to electrical stimulation and Nd:YAG LEPs. VT and SEPs were used to assess large-diameter afferent nerve fibres and the lemniscal pathways while TT and LEPs were used to assess small-diameter afferent nerve fibres and the spinothalamic tract. In addition, patients with peripheral neuropathy underwent also standard nerve conduction studies to explore large fibres and the recording of sympathetic skin responses (SSRs) to explore small fibres, whereas motor evoked potentials were performed in patients with spinal cord lesion. LEPs were absent bilaterally in all patients with polyneuropathy, even when TT remained within the normal limits and SSRs were present. LEPs were absent after stimulation of the affected limb in all patients with a spinal cord lesion, and allowed to detect subclinical contralateral lesion in two cases. LEPs following Nd:YAG laser stimulation are sensitive in the diagnosis of peripheral and/or central nervous system disorders and they give complementary information as compared to routine electrophysiological tests.

The role of myoglobin in retarding oxygen depletion in anoxic heart.

The present study explores the role of myoglobin (Mb) in retarding the development of anoxia in the perfused working rat heart. We examine this phenomenon by analyzing the behavior and the kinetics of Mb oxygenation and cytochrome aa3 (cytaa3) redoxation. Absorbance changes, measured at wavelength pairs specific to Mb and cytaa3, show parallelism between the Mb oxygenation status and the redox states of cytaa3. Induction of anoxia leads to early and accelerated Mb deoxygenation whereas cytaa3 reduction marks a slight delay and its rate is twice slower than that of Mb. Then, when Mb is desatured above 50%, the cytaa3 reduction becomes accelerated. With the reoxygenated perfusion following the anoxia, the rate of Mb reoxygenation is twice faster than that of the cytaa3 reoxidation. When the oxygen-binding function of Mb, in situ in the heart, is abolished by treatment with sodium nitrite (NaNO2), the redox kinetics of cytaa3 show significant perturbations. Induction of anoxia leads to a precocious and accelerated reduction of cytaa3, compared to the same anoxic heart before the treatment. At reoxygenation, the reoxidation rate of cytaa3 decreases significantly, compared to that before the treatment. Similarly, in the nitrite treated heart, the phosphocreatine (PCr) level decreases to 60% of the control, whereas the inorganic phosphate (Pi) level increases to 300%. ATP concentration, however, remains constant. We conclude from these results that Mb may support mitochondrial respiration at the critical levels of the myocardial O2 supply.

[Dissection of the aorta complicated by aorto-pulmonary fistula]. / Dissection aortique compliquée de fistule aorto-pulmonaire.

The authors report the case of chronic dissection of the aorta presenting with congestive cardiac failure. The diagnosis was made for the first time by transoesophageal echocardiography which showed both the dissection of the aorta and its fistulalisation into the pulmonary artery. Aortography confirmed the diagnosis. The patient underwent surgery which consisted of suture of the fistula and replacement of the ascending aorta with a prosthetic tube. The outcome was favourable after 8 months follow-up.

Laser evoked potentials using the Nd:YAG laser.

Pain-related cortical potentials were evoked by skin stimulation of the face and the limbs with 5-ns-duration laser pulses delivered by a Q-switched Nd:YAG laser. Such laser pulses, in the nanosecond range, were able to induce pinprick pain sensations and to evoke reproducible laser evoked potentials (LEPs) without visible skin lesions for an energy density of less than 18 mJ/mm(2). Low energy densities, around 10 mJ/mm(2), were sufficient to reach the pain threshold and to induce LEP. The mean conduction velocity of the stimulated afferent fibers was close to 20 m/s, consistent with the stimulation of Adelta fibers. The amplitude of LEP correlated with pain perception rather than with energy density. The differences, such as wavelength and stimulus duration, between the Q-switched Nd:YAG laser we used and the lasers that are currently used in LEP studies (i.e., CO(2), argon, or Tm:YAG lasers in the millisecond range) are discussed. Our study opens novel perspectives in the LEP field of research by using a new type of laser with a very short pulse duration.

Congestive heart failure and myocarditis after seroconversion for toxoplasmosis in two immunocompetent patients.

Two cases of myocarditis and congestive heart failure in immunocompetent patients with seroconversion for toxoplasmosis are reported. Serological tests showed that in the first case the cardiac manifestations occurred at the time of seroconversion (low IgG, raised IgM and IgA), whereas in the second case they occurred several months after the initial infection when IgM was decreasing, IgG levels were very high (>1000 IU/ml) and IgG had high affinity for the antigen. The pathophysiological mechanisms underlying cardiac involvement in acute or chronic toxoplasmosis are discussed.

[Effect of the moon on the nocturnal postnuptial migration of the skylark Alauda arvensis L. in France]. / Effet de la lune sur la migration postnuptiale nocturne de l'alouette des champs Alauda arvensis L. en France.

Night-migrating skylarks (Alauda arvensis) were captured during four successive autumns in France. The study aimed at detecting a possible influence of the lunar cycle on the nocturnal migration of this species. Though nocturnal postnuptial migration of the skylarks can occur during every phase of the moon, main nocturnal movements occurred when the moon was in its waxing gibbous phase. This phase gives the best conditions for migration because from the very beginning of night, it provides the necessary horizon for individuals to navigate and its light allows the use of topographic cues. In addition it allows the species to benefit from optimal conditions of illumination for almost a week.

Anisotropy and multiple scattering in thick mammalian tissues.

A dual-channel Mach-Zehnder interferometer using heterodyne detection allowed us to measure simultaneously parallel and perpendicular polarization components through various mammalian tissues at a wavelength of lambda = 633 nm. By contrast with liver tissue, squeletic muscles of a few millimeters thickness exhibit strong anisotropic properties that change the direction of the linear polarization of the light. This rotation of the initial plane of polarization is to be distinguished from the depolarization that is due to the multiple light scattering that goes along with large temporal fluctuations. Complementary photos under linearly polarized light illustrate the behavior difference between liver (isotropic medium) and muscle (anisotropic medium).

Coronary-to-bronchial artery communication: report of two patients successfully treated by embolization.

We report two cases of coronary-to-bronchial artery communication responsible for coronary steal. In both cases the anastomosis originated from the proximal circumflex artery and developed because of bronchiectasis. In both cases closure of the anastomosis was achieved successfully by embolization. To date, the patients remained free from symptoms.

[Drug therapy of ventricular tachycardia]. / Traitement médicamenteux des tachycardies ventriculaires.

Despite the introduction of new therapeutic techniques such as radiofrequency ablation and the implantable defibrillator, the classical opposition of monomorphic ventricular tachycardia in apparently normal hearts and that arising from documented cardiac disease remains useful. In the first case, treatment is only symptomatic whereas, in the second, lethal progression to sudden death must be prevented. Generally speaking, in chronic post-infarct situations, betablockers are underused although they have been shown beyond doubt to reduce cardiovascular mortality. This is probably explained by the fear of possible haemodynamic decompensation in patients who often have left ventricular dysfunction. Nevertheless, different randomised studies of the use of betablockers in cardiac failure have reported reduced mortality with no serious side effects. The use of beta-blockers is therefore advisable, and possible inpatients with or without sustained ventricular tachycardia and underlying cardiac disease. In cases at high risk of sudden death, amiodarone may be associated. Recent randomised studies (MADIT, AVID), comparing the use of implantable defibrillators with those of antiarrhythmic therapy, have shown better results with the implantable defibrillator. However, in these studies, only about 10% of patients received betablockers in the antiarrhythmic treatment groups. This factor has introduced some doubt as to the real benefit of implantable defibrillators. Therefore, a randomised study comparing the efficacy of betablockers with amiodarone against implantable defibrillators is desirable in order to determine the respective indications of each of these two therapeutic modalities.

Coherence and polarization of light propagating through scattering media and biological tissues.

The degree of polarization of light propagating through scattering media was measured as a function of the sample thickness in a Mach-Zehnder interferometer at a wavelength of lambda = 633 nm. For polystyrene microspheres of diameters 200, 430, and 940 nm, depolarization began to appear for thicknesses larger than 23, 19, and 15 scattering mean free paths (SMFP's), respectively, where the coherently detected scattered component dominates the ballistic component. For large particles (940 nm) the initial polarization survived partially in the scattering regime and progressively vanished up to the detection limit of our setup. This phenomenon was similarly observed in diluted blood from 12.5 to 280 SMFP's. Beyond this thickness the fluctuating parallel and crossed components of polarization became random. A dual-channel interferometer allowed us to detect simultaneously the low-frequency fluctuations of both polarized components through a few millimeters in liver tissue.