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1.
Ann Dermatol Venereol ; 147(6-7): 456-460, 2020.
Article in French | MEDLINE | ID: mdl-32229034

ABSTRACT

INTRODUCTION: Lichenoid cutaneous reactions to antituberculosis drugs are rare. Herein we report a new case. PATIENTS AND METHODS: A 41-year-old patient was seen for a profuse and pruriginous rash occurring 2 weeks after administration of rifampicin and isoniazid for pulmonary tuberculosis. Dermatological examination revealed polymorphic erythemato-squamous plaques with lichenoid, psoriatic and eczematous features, associated with cheilitis, erosions on the cheeks and diffuse onychodystrophy. The skin biopsy confirmed a lichenoid reaction. The pharmacovigilance investigation incriminated isoniazid and rifampicin. The patient was treated with topical corticosteroids and UVB phototherapy. The outcome involved complete regression of the eruption but with secondary anonychia. DISCUSSION: Antituberculosis drugs including isoniazid and rifampicin are known to induce lichenoid reactions. It is difficult to distinguish the results from lichen planus. The clinical polymorphism of the rash as well as the patient's drug intake militate in favour of a diagnosis of lichenoid reaction. Widespread ungual involvement, which is extremely rare, warranted early management in order to avert irreversible anonychia.


Subject(s)
Antitubercular Agents/adverse effects , Drug Eruptions/etiology , Isoniazid/adverse effects , Lichenoid Eruptions/chemically induced , Nail Diseases/chemically induced , Rifampin/adverse effects , Adult , Drug Eruptions/complications , Humans , Isoniazid/therapeutic use , Lichenoid Eruptions/complications , Male , Nail Diseases/complications , Rifampin/therapeutic use , Tuberculosis, Pulmonary/drug therapy
2.
Appl Opt ; 58(24): 6638-6654, 2019 Aug 20.
Article in English | MEDLINE | ID: mdl-31503596

ABSTRACT

An international round-robin experiment has been conducted to test procedures and methods for the measurement of angle-resolved light scattering. ASTM E2387-05 has been used as the main guide, while the experience gained should also contribute to the new ISO standard of angle-resolved scattering currently under development (ISO/WD 19986:2016). Seven laboratories from Europe and the United States measured the angle-resolved scattering from Al/SiO2-coated substrates, transparent substrates, volume diffusors, quasi-volume diffusors, white calibration standards, and grating samples at laser wavelengths in the UV, VIS, and NIR spectra. Results were sent to Fraunhofer IOF, which coordinated the experiments and analyzed the data, while ESA-ESTEC, as the project donor, defined conditions and parameters. Depending mainly on the sample type, overall good to reasonable agreements were observed, with largest deviations at scattering angles very close to the specular beam. Volume diffusor characterization unexpectedly turned out to be challenging. Not all participants provided measurement uncertainty ranges according to the Guide to the Expression of Uncertainty in Measurement; often, a single general scatterometer-related measurement uncertainty value was stated. Although relative instrument measurement uncertainties close to 1% are sometimes claimed, the comparison results did not support these claims for specular scattering samples as mirrors, substrates, or gratings.

3.
Arch Pediatr ; 24(9): 833-836, 2017 Sep.
Article in French | MEDLINE | ID: mdl-28734809

ABSTRACT

The use of traditional products for therapeutic purposes in the newborn cause many cases of severe poisoning, especially in newborns. The aim of this study was to identify the main medicinal plants causing poisoning and emphasize the seriousness of poisonous plants. We report a series of eight newborns admitted for intake of poisonous medicinal plants admitted to the neonatal unit and neonatal intensive care unit at the Fez (Morocco) Hassan II University Hospital in 2014. The reasons for use were dominated by the infant's refusing to suckle. Clinical signs at admission were neurological signs and respiratory distress. The decision was spontaneously declared by the family for only two patients. A particular smell of the urine and unusual lesion associations were the main signs drawing the attention of physicians in other cases. The amounts and rates differed. Laboratory tests revealed renal failure in two cases. Transaminases (SGOT and SGPT) were greater than three times normal and the TP was below 50% in two newborns. Hemoglobin less than 9g/dL in three cases and thrombocytopenia less than 50,000/mm3 in two newborns. The main poisonous plants were identified as cade oil and henna. Medicinal plants were associated in all cases. Toxicological analysis was negative in three cases and was not done in the other five cases. The management was symptomatic and etiological. The outcome was favorable in six newborns. Death occurred in two neonates despite resuscitation. Medicinal plants must, like drugs, obey strict rules that only the standard herbal medicine specialist can answer. This necessarily involves the regulation of the profession in our country.


Subject(s)
Medicine, Traditional/adverse effects , Plant Extracts/poisoning , Female , Humans , Infant , Infant, Newborn , Male , Retrospective Studies , Severity of Illness Index
5.
Morphologie ; 101(332): 1-8, 2017 Mar.
Article in English | MEDLINE | ID: mdl-27426252

ABSTRACT

Among the bearing surfaces involved in a total hip arthroplasty, ultra-high molecular weight polyethylene (UHMWPE) is the weak link. It is submitted to the friction of a harder bearing, producing wear particles, which, in turn, initiate an inflammatory reaction ultimately leading to osteolysis. This kind of bone deterioration sometimes turns out to an aggressive granuloma and may provoke implant loosening. Wear resistance of UHMWPE depends on its molecular weight and crystallinity. Some steps of the manufacturing process were improved to optimize its tribological properties and to slow down degradation resulting from mechanical (abrasion) and chemical (oxidation) phenomena. Its preparation and conservation must be performed in an inert atmosphere, i.e. without ambient oxygen. Its resistance to abrasion depends on its cross-linking degree. Its cross-linking rate was observed to increase proportionally to the irradiation doses, improving its wear resistance. However, its mechanical properties are impaired and moreover, it becomes oxidation sensitive. It is therefore necessary to submit it to a thermal treatment to eliminate free radicals that were produced during irradiation. More recently impregnation by vitamin E, a powerful anti-oxidant product, was proposed to preserve the polymer from in vivo oxidation while maintaining its mechanical properties. We raised the hypothesis that last-generation UHMWPE could offer the same wear resistance as the most performing bearings (ceramic-on-ceramic). Recent clinical results confirm the tribological performance of highly crosslinked UHMWPE in vivo. However, it remains to be seen whether this excellent wear resistance would persist under eccentric load such as edge loading, and if, in the long run, this kind of bearing proves capable of reducing the risk of osteolysis in young and active patients.


Subject(s)
Arthroplasty, Replacement, Hip/instrumentation , Hip Prosthesis/adverse effects , Osteolysis/etiology , Polyethylenes/chemistry , Prosthesis Failure , Antioxidants/pharmacology , Arthroplasty, Replacement, Hip/adverse effects , Ceramics , Humans , Materials Testing , Molecular Weight , Osteolysis/complications , Oxidation-Reduction , Polyethylenes/adverse effects , Polyethylenes/therapeutic use , Prosthesis Design , Vitamin E/pharmacology
6.
BMC Public Health ; 16: 468, 2016 06 04.
Article in English | MEDLINE | ID: mdl-27262322

ABSTRACT

BACKGROUND: Data on psychoactive substance (PAS) consumption among adolescents in the North Center of Morocco are not at all available. Therefore, the current study aimed at investigating the prevalence and the determinants of psychoactive substances use among middle and high school students in this region. METHODS: A cross-sectional study was conducted from April 2012 to November 2013 in public middle and high schools in the North Central Region of Morocco. An anonymous self-administered questionnaire was used to assess psychoactive substances use among a representative sample of school students from the 7th to the 12th grade, aged 11-23 years, selected by stratified cluster random sampling. Factors associated with psychoactive substance use were identified using multivariate stepwise logistic regression analyses. RESULTS: A total of 3020 school students completed the questionnaires, 53.0 % of which were males. The overall lifetime smoking prevalence was 16.1 %. The lifetime, annual and past month rates of any psychoactive substance use among the study subjects were 9.3, 7.5, and 6.3 % respectively. Cannabis recorded the highest lifetime prevalence of 8.1 %, followed by alcohol 4.3 %, inhalants 1.7 %, psychotropic substances without medical prescription 1.0, cocaine 0.7, heroine 0.3, and amphetamine with only 0.2 %. Psychoactive substance use was associated with males more than females. The risk factors identified by multivariate stepwise logistic regression analyses were being male, studying in secondary school level, smoking tobacco, living with a family member who uses tobacco, and feeling insecure within the family. CONCLUSIONS: The prevalence among all school students reported by the current study was comparable to the national prevalence. Efforts to initiate psychoactive substance prevention programs among school students should be made by designing such programs based on the significant factors associated with psychoactive substance use identified in this study.


Subject(s)
Adolescent Behavior , Psychotropic Drugs , Students/statistics & numerical data , Substance-Related Disorders/epidemiology , Adolescent , Adolescent Health Services , Child , Cross-Sectional Studies , Female , Humans , Male , Morocco/epidemiology , Prevalence , Risk Factors , Schools , Substance-Related Disorders/psychology , Surveys and Questionnaires , Young Adult
7.
Arch Environ Contam Toxicol ; 68(3): 442-50, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25511562

ABSTRACT

The study objectives were to estimate lead poisoning prevalence among children living next to an industrial area, to compare it to that in a control population, and to establish clinical and biological follow-up of the poisoned children. This is a descriptive cross-sectional study including 150 children (exposed and unexposed) performed between January 2012 and April 2013. It was meant to determine blood lead levels (BLLs) in children considered to be an exposed population (EP N 90), living in the industrial area Ain Nokb Fez compared with BLLs of children of other areas belonging to the same city supposed to be unexposed [UP (N = 60)]. A sociodemographic questionnaire was obtained, and a blood lead analysis was performed. Clinical and biological follow-up has been performed of poisoned children. The sample consisted of 90 EP children with an average age of 6.82 ± 3.32 years and male-to-female sex ratio (SR) of 1.5 and 60 UP children with an average age of 6.45 ± 3.29 years and an SR of 1.2. Among the 150 children recruited, the average of BLLs was 58.21 ± 36 µg/L (18-202.3 µg/L). The average of BLLs in EP children (71 ± 40 µg/L) was statistically greater (p < 0.0001) than that registered in UP children (38 ± 13 µg/L). All poisoned children belonged to the EP group at a prevalence of 21.1 %. The clinical and biological examinations of poisoned children showed a few perturbations such as anemia, hypocalcaemia, and deficiencies in magnesium and iron. No renal disease or objective neurological disorders were observed. In the follow-up of the children with BLL ≥100 µg/L (19 cases). BLL monitoring showed a significant decrease in average of blood concentration ranging from 136.75 ± 32.59 to 104.58 ± 32.73 µg/L (p < 0.0001) and in lead poisoning prevalence (p < 0.001), which decreased to 7.8 % from 21.1. Our study showed a high prevalence of lead poisoning (21.1 %) in EP children. The relocation of the industrial site associated with corrective and preventive measures has contributed to a decrease of exposure and lead poisoning prevalence in the aforementioned population.


Subject(s)
Environmental Exposure/statistics & numerical data , Environmental Pollutants/blood , Lead Poisoning/diagnosis , Lead/blood , Child , Child, Preschool , Cross-Sectional Studies , Environmental Exposure/analysis , Female , Humans , Industry , Lead Poisoning/blood , Lead Poisoning/epidemiology , Male , Morocco/epidemiology , Prevalence
9.
Bull Soc Pathol Exot ; 106(1): 48-53, 2013 Feb.
Article in French | MEDLINE | ID: mdl-22311510

ABSTRACT

In Morocco, the Marrakech-Tensift-Al Haouz region is one of the 16 regions most affected by poisoning. The aim of this study was to determine the epidemiological profile of poisoning recorded in the study region. A retrospective study of poisoning cases, declared between 1981 and 2008 in the Morocco Poison Control and Pharmacovigilance Center, was conducted. During the study period, 8517 poisoning cases were collected. The average age of patients was 22 ± 15 years. The male/female sex ratio was 0.85. Food poisoning was the most reported in the region, with 26.6% of cases. Among the 2,779 patients for whom the outcome was known, 65 died, with lethality rate of 23.4‰. The maximum lethality rate was recorded among those poisoned by paraphenylenediamine (170.7‰).


Subject(s)
Poisoning/epidemiology , Adolescent , Adult , Child , Child, Preschool , Female , Geography , Humans , Male , Morocco/epidemiology , Poisoning/diagnosis , Poisoning/etiology , Poisoning/mortality , Retrospective Studies , Severity of Illness Index , Time Factors , Young Adult
10.
East Mediterr Health J ; 19(11): 953-9, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24673087

ABSTRACT

In Morocco, acute Atractylis gummifera L. poisoning represents the leading cause of death by plant poisoning especially for children. All cases received in the Moroccan poison control centre from January 1981 to December 2009 (n = 467) were included in a retrospective study of the characteristics and risk factors of A. gummifera L. poisoning. The most vulnerable age group was children (63.4% of cases). Most cases were due to accidental exposure (75.5%), but some were from therapeutic use (18.1%) or attempted abortion (7.4%). Patients presented with moderate poison severity signs (grade 2) in 22.3% of cases or severe signs (grade 3) in 21.0%. The mortality rate was 39.2%. The majority of deaths (81.1%) occurred in children aged < 15 years following accidental exposure. Multivariate logistic regression analysis revealed that risk factors for mortality were coma (OR = 20.5); hepatitis (OR = 52.7) and rural residence (OR = 7.26), while gastric decontamination was a protector factor (OR = 0.26).


Subject(s)
Atractylis/poisoning , Adolescent , Adult , Aged , Child , Child, Preschool , Female , Humans , Infant , Logistic Models , Male , Middle Aged , Morocco/epidemiology , Plant Poisoning/mortality , Prognosis , Retrospective Studies , Risk Factors , Young Adult
11.
Med Sante Trop ; 22(1): 84-6, 2012.
Article in French | MEDLINE | ID: mdl-22868734

ABSTRACT

Peganum harmala L. (wild or Syrian rue) is commonly used as an emmenagogue and abortifacient in traditional medicine in the Middle East and North Africa including Morocco. The purpose of this report is to describe two cases of Peganum harmala L. poisoning in pregnant women. Both cases were treated successfully with good maternal-fetal outcome good for mother and child.


Subject(s)
Abortion, Induced/adverse effects , Abortion, Induced/methods , Peganum/poisoning , Pregnancy Complications/etiology , Adolescent , Female , Humans , Morocco , Pregnancy , Young Adult
12.
Arch Pediatr ; 19(1): 59-61, 2012 Jan.
Article in French | MEDLINE | ID: mdl-22169568

ABSTRACT

Indigo, also known in Morocco as Nila, is a dye widely used in the coloring of Moroccan handicrafts. It is obtained from fermentation reactions on the leaves and branches of true indigo, Indigofera tinctoria, which is a widespread plant in tropical Africa and Asia. We report a case of fatal poisoning in a 3-year-old child after administration of indigo for therapeutic purposes. Death resulted from multiple organ failure. The toxicity of this compound is little known in the literature and deserves to be explored through toxicokinetic and toxicodynamic studies, in order to better determine the toxic constituents of the dye.


Subject(s)
Coloring Agents/poisoning , Enteritis/complications , Indigofera/poisoning , Phytotherapy/adverse effects , Child, Preschool , Coloring Agents/chemistry , Enteritis/drug therapy , Fatal Outcome , Humans , Indigofera/chemistry , Male , Plant Leaves/poisoning
13.
Neurochem Int ; 57(4): 440-5, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20193723

ABSTRACT

Synaptic plasticity consists in a change in synaptic strength that is believed to be the basis of learning and memory. Synaptic plasticity has been for a very long period of time a hallmark of neurons. Recent advances in physiology of glial cells indicate that astrocyte and microglia possess all the features to participate and modulate the various form of synaptic plasticity. Indeed beside their respective supportive and immune functions an increasing number of study demonstrate that astrocytes and microglia express receptors for most neurotransmitters and release neuroactive substances that have been shown to modulate neuronal activity and synaptic plasticity. Because glial cells are all around synapses and release a wide variety of neuroactive molecule during physiological and pathological conditions, glial cells have been reported to modulate synaptic plasticity in many different ways. From change in synaptic coverage, to release of chemokines and cytokines up to dedicated "glio" transmitters release, glia were reported to affect synaptic scaling, homeostatic plasticity, metaplasticity, long-term potentiation and long-term depression.


Subject(s)
Neuroglia/physiology , Neuronal Plasticity/physiology , Synapses/physiology , Animals , Astrocytes/physiology , Cell Communication/physiology , Humans , Inflammation/pathology , Neuroglia/ultrastructure , Neurons/physiology , Neurotransmitter Agents/physiology , Synapses/ultrastructure , Synaptic Transmission/physiology
14.
East Mediterr Health J ; 15(5): 1145-55, 2009.
Article in English | MEDLINE | ID: mdl-20214128

ABSTRACT

We determined the prevalence of adverse drug events (ADEs) in a general teaching hospital in Rabat, Morocco. We performed a 5-day cross-sectional study of hospital departments recruiting inpatients and outpatients. Among the 1390 patients surveyed, 59 (4.2%) experienced at least 1 ADE and for 20 patients (1.4%) the ADE was responsible for hospitalization or prolongation of hospitalization. The ADE was classified as serious in 28 patients. Of the total of 76 ADEs, 10 (13.2%) were categorized as preventable; 6 of these occurred during the treatment monitoring phase. Patients who experienced an ADE were more likely to be women, to be younger (< 30 years) and to be hospitalized in medical departments.


Subject(s)
Drug-Related Side Effects and Adverse Reactions , Hospitals, General , Hospitals, Teaching , Medication Errors , Adult , Adverse Drug Reaction Reporting Systems , Aged , Chi-Square Distribution , Cross-Sectional Studies , Drug Monitoring , Drug-Related Side Effects and Adverse Reactions/chemically induced , Drug-Related Side Effects and Adverse Reactions/epidemiology , Drug-Related Side Effects and Adverse Reactions/prevention & control , Female , Hospitals, General/statistics & numerical data , Hospitals, Teaching/statistics & numerical data , Humans , Length of Stay/statistics & numerical data , Male , Medication Errors/mortality , Medication Errors/prevention & control , Medication Errors/statistics & numerical data , Middle Aged , Morbidity , Morocco/epidemiology , Pharmacoepidemiology , Prevalence , Risk Factors , Severity of Illness Index , Statistics, Nonparametric
15.
(East. Mediterr. health j).
in English | WHO IRIS | ID: who-117744

ABSTRACT

We determined the prevalence of adverse drug events [ADEs] in a general teaching hospital in Rabat, Morocco. We performed a 5-day cross-sectional study of hospital departments recruiting inpatients and outpatients. Among the 1390 patients surveyed, 59 [4.2%] experienced at least 1 ADE and for 20 patients [1.4%] the ADE was responsible for hospitalization or prolongation of hospitalization. The ADE was classified as serious in 28 patients. Of the total of 76 ADEs, 10 [13.2%] were categorized as preventable; 6 of these occurred during the treatment monitoring phase. Patients who experienced an ADE were more likely to be women, to be younger [< 30 years] and to be hospitalized in medical departments


Subject(s)
Drug-Related Side Effects and Adverse Reactions , Prevalence , Hospitals, Teaching , Cross-Sectional Studies , Age Distribution , Sex Distribution , Drug-Related Side Effects and Adverse Reactions
16.
J. venom. anim. toxins incl. trop. dis ; 15(2): 255-267, 2009. tab
Article in English | LILACS, VETINDEX | ID: lil-517284

ABSTRACT

Scorpion stings are a public health problem in Morocco, especially among children, who experience the most severe cases. Epidemiological and clinical findings on scorpion stings in Fez, Morocco, were evaluated in this investigation. Of 163 cases that required medical attention, 62.6 percent were male children. The mean age of patients was 4.8 ± 3.4 years. The mean time between stings and first medical attention was 3.36 ± 2.5 hours. Almost all cases occurred in the summer (94 percent) and extremities represented the most frequent sting sites (86.5 percent). Local pain, hyperemia, scarification, vomiting, sweating, restlessness, tachycardia and tachypnea were the observed clinical symptoms. Regarding severity, 55.2 percent of patients belonged to class III, followed by class II (26.4 percent) and class I (18.4 percent). None of our patients received antivenom; however, all of them were treated symptomatically depending on clinical manifestations.(AU)


Subject(s)
Humans , Child , Epidemiologic Studies , Public Health , Scorpion Stings , Antivenins
17.
Ann Readapt Med Phys ; 44(1): 35-40, 2001 Feb.
Article in French | MEDLINE | ID: mdl-11587653

ABSTRACT

OBJECTIVES: To confirm the efficiency of intracavernous injections in the treatment of erectile dysfunction in spinal cord injured (SCI) patients and to determine the mean necessary dose to obtain functional erection. MATERIALS: This prospective study concerns 36 spinal cord injured men. None of them had erectile dysfunction before the neurologic impairement. Sixty four intracavernous injections were performed. METHOD: The first injection was done with the usually recommended starting dose. The injections were then repeated with increasing dosage to archive a rigid erection. The erection was evaluated with Schramek grading. A grade 4 or 5 erection was considered as functional. RESULTS: Nine tetraplegics and 27 paraplegics were included. Twenty two were grade A in ASIA classification. The mean age was 31 years. Twenty for patients had a level above T10, 11 between T11 and L2, one below L2. Twenty seven patients obtained an erection of grade 4 or 5. Alprostadil was used 51 times, moxisylite nine times and papaverine four times. The average dose necessary to obtain a grade 4 or 5 functional erection adequate for coitus was 12.3 +/- 4.8 microgram with alprostadil and 14 +/- 5.4 mg with moxisylite. No side effects were noted. The nine left patients did not archive satisfying erection during this study. No clinical differences were noted in this population, compared with the 27 other patients. CONCLUSION: The findings confirm the efficiency of intracavernous injections in the management of erectile dysfunction in SCI. The average doses required to obtain a functional erection was 12.3 (+/- 4.8) microgram with alprostadil and 14 (+/- 5.4) mg with moxisylyte.


Subject(s)
Alprostadil/administration & dosage , Erectile Dysfunction/drug therapy , Moxisylyte/administration & dosage , Papaverine/administration & dosage , Spinal Cord Injuries/complications , Vasodilator Agents/administration & dosage , Adult , Alprostadil/pharmacology , Erectile Dysfunction/etiology , Humans , Male , Moxisylyte/pharmacology , Papaverine/pharmacology , Patient Satisfaction , Vasodilator Agents/pharmacology
18.
J Am Med Inform Assoc ; 8(4): 351-60, 2001.
Article in English | MEDLINE | ID: mdl-11418542

ABSTRACT

Decision support systems in the medical field have to be easily modified by medical experts themselves. The authors have designed a knowledge acquisition tool to facilitate the creation and maintenance of a knowledge base by the domain expert and its sharing and reuse by other institutions. The Unified Medical Language System (UMLS) contains the domain entities and constitutes the relations repository from which the expert builds, through a specific browser, the explicit domain ontology. The expert is then guided in creating the knowledge base according to the pre-established domain ontology and condition-action rule templates that are well adapted to several clinical decision-making processes. Corresponding medical logic modules are eventually generated. The application of this knowledge acquisition tool to the construction of a decision support system in blood transfusion demonstrates the value of such a pragmatic methodology for the design of rule-based clinical systems that rely on the highly progressive knowledge embedded in hospital information systems.


Subject(s)
Artificial Intelligence , Blood Transfusion , Decision Support Systems, Clinical , Unified Medical Language System , Decision Making, Computer-Assisted , Expert Systems , Humans , Software , Software Design
19.
Proc AMIA Symp ; : 187-91, 1999.
Article in English | MEDLINE | ID: mdl-10566346

ABSTRACT

Blood transfusion is a medical domain where decision support systems (DSSs) could be very helpful to the physicians but must easily and continuously be maintained. We have developed a knowledge acquisition tool that allows the construction and the maintenance of such a system by the domain expert. The methodology used could be applied to another highly evolutive medical domain. In this paper, we detail our knowledge acquisition tool, its use and the final DSS obtained, which is fully integrated into our hospital information network.


Subject(s)
Artificial Intelligence , Blood Transfusion , Decision Support Systems, Clinical , Hospital Information Systems , Humans , Software , Unified Medical Language System , Vocabulary, Controlled
20.
Acta Biotheor ; 43(4): 363-72, 1995 Dec.
Article in English | MEDLINE | ID: mdl-8919348

ABSTRACT

The present work is aimed at investigating the effects of myocardial infarction and ischemia on induction of ventricular fibrillation. Electrophysiologic effects of global and local ischemia (variation of the dispersion of refractory periods as well as conduction velocity) on initiation of reentry mechanisms was studied by means of computer simulations based on a cellular automata model of propagation of activation wave through a ventricular surface element. A local area of ischemia where effects of the dispersion of refractory periods are investigated is then simulated. This is made using a Gaussian distribution characterized by its mean and standard deviation. These simulations show that ischemia is capable of initiating reentry phenomena which propagate through the whole ventricle; they are responsible for ventricular fibrillation which causes sudden cardiac death, even when ischemia only involves limited parts of the myocardium. Statistical study of the probability of reentries as a function of both of the size of ischemic zones and the rate of dispersion of refractory periods shows that the latter parameter is of primary importance in triggering cardiac reentries.


Subject(s)
Electrocardiography , Myocardial Infarction/physiopathology , Myocardial Ischemia/physiopathology , Tachycardia, Atrioventricular Nodal Reentry/physiopathology , Ventricular Fibrillation/physiopathology , Cell Hypoxia/physiology , Computer Simulation , Death, Sudden, Cardiac/etiology , Humans , Models, Cardiovascular , Nonlinear Dynamics , Normal Distribution , Ventricular Function
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