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Biomedical subjects

C Claessens

Publications and source records attributed to C Claessens.

8 recordsLinked to original sources
PubMed2000

Physiological or pseudophysiological ECG changes in endurance-trained athletes.

"Sudden cardiac death" in seemingly healthy, active, and asymptomatic people has always been a tragic fact and is now occurring more frequently. Thus, the preventive detection of "subjects at risk" becomes a priority. A traditional resting electrocardiogram can sometimes give useful indications. Fifty-two competitive triathletes were compared with 22 control persons with similar anthropometric parameters. All subjects underwent the same noninvasive cardiac exploration with electrocardiography, bidimensional echo-Doppler examination, and maximal spiroergometric exercise tests, on a stationary bicycle as well as on a treadmill. In the triathletes we noted manifest signs of eccentric as well as concentric left ventricular hypertrophy with arguments for a supernormal diastolic left ventricular function, with important hemodynamic adjustments and with consequences on the resting electrocardiogram. We described "ten commandments" in evaluating the resting electrocardiogram of healthy competitive athletes. We suspect that the occurrence of ventricular premature beats at peak load of a maximal exercise could be the first expression of a pathological cardiac adaptation to sports activities. The resting electrocardiogram can show interesting details in detecting the "subjects at risk" for problems such as possible lethal arrhythmias and "sudden cardiac death." The analysis of the four subgroups of triathletes compels us to feel dubious about the "athletic heart syndrome" as a physiological entity. In several cases the "athletic heart" is possibly a transitional situation to a pathological hypertrophic and dilated cardiomyopathy.

Adult↗
PubMed2000

Prevalence of HIV infection and risk behaviours among Montreal street youth.

We aim to estimate HIV prevalence and associated risk factors among street youth in Montreal, Canada. We conducted a one-year cross-sectional anonymous study in 1995. We recruited youth aged 13-25 years meeting specific criteria for itinerancy through the 20 major Montreal street youth agencies. Participation included a structured interview and provision of an oral specimen for HIV testing. Among the 909 subjects studied, 99.3% had been sexually active, 25.9% had exchanged sex for money, gifts, drugs, a place to sleep, or other things; 31.8% reported anal sex; and 36.4% reported having ever injected drugs. Overall, HIV prevalence was 1.9% (1.1% in girls and 2.2% in boys). Multivariate logistic regression showed that being over 20 years of age (adjusted odds ratio (AOR) 7.09), having injected drugs (AOR 4.48), having engaged in prostitution (AOR 3.32), and being born outside Canada (AOR 4.41) were all independently associated with HIV infection.

Adolescent↗
PubMed2000

Changes in mortality of acute myocardial infarction as a function of a changing treatment during the last two decades.

Forty years ago, after the establishment of coronary care units, a significant decrease in mortality of acute myocardial infarction was noted. Twenty years ago, the break-through of thrombolysis realized once again a significant decrease in mortality. In this study we compare, in a rather small community hospital, the mortality and safety of thrombolytic therapy in acute myocardial infarction with a more conventional, conservative medical therapy. We examined all cases of acute myocardial infarction between 1978 up to 1998 inclusive, concerning treatment and mortality rate after a six month period. To be included in the study, acute myocardial infarction had to fulfill particular inclusion criteria. A total of 1863 cases of acute myocardial infarction were included. The mortality rate of patients with acute myocardial infarction treated with thrombolytic agents was strikingly lower and statistically very significantly different (p < 0.001) in comparison with the mortality rate of patients treated with heparin or coumarine derivatives. The mortality rate dropped from 10.57% in the coumarine group and from 14.95% in the heparin group to 5.41% in the alteplase group, to 4.95% in the anistreplase group and 4.00% in the streptokinase subgroup. The complications directly connected to the treatment did not seem to be different between the five groups, and they were also not more frequent by using thrombolytic agents. In the last 20 years, better preventive measures (life habits, diet, medication) and trials to better control the risk factors have not influenced greatly the average amount of cholesterol in patients with an acute myocardial infarction. Also the percentage of patients with high blood pressure has hardly decreased over the last 20 years. The mortality associated with acute myocardial infarction has decreased significantly with the use of thrombolytics. In most cases, thrombolytics are administered routinely and safely. In this way, they are the first choice therapy for myocardial infarction in smaller hospitals. To obtain excellent coronary patency, thrombolytic agents with a long half-life and with PAI-1 resistance are required in the future. The current measures and medical therapies seem to be insufficient to control the risk factors for coronary atherosclerosis.

Cholesterol↗
PubMed1999

Ventricular premature beats in triathletes: still a physiological phenomenon?

UNLABELLED: Sudden death is a tragic fact, unexpectedly arising in all age groups. Ventricular arrhythmias are the main cause. At the end of a maximal exercise test more ventricular premature beats were noted in a group of well trained triathletes compared with a similar control group. The etiology is multifactorial. When these ventricular premature beats are associated with specific structural and functional heart adaptations, echocardiographically and electrocardiographically well-documented, then those 'banal' ventricular premature beats cannot longer be considered as a physiological phenomenon. In these circumstances the involved subject is a candidate for dangerous arrhythmias and 'sudden cardiac death'. PURPOSE: The principal cause of 'Sudden cardiac death' is ventricular arrhythmias. We explore the incidence of ventricular premature beats (VPB) in triathletes, who engage in enforced endurance sports. METHODS: Fifty-two triathletes were compared with twenty-two control subjects with comparable anthropometric parameters in function of structural and functional cardiac adaptations. Maximal exercise tests were conducted on a stationary bicycle and a treadmill. During the last two minutes of each test, the VPB were registered. RESULTS: Statistically significant differences emerged in the cardiac structure and function between the triathletes and the controls. There were signs of cardiac hypertrophy and arguments for a supernormally diastolic left ventricular function in the triathletes. The performance capacity was also significantly higher in the triathletes. The maximal heart rate was significantly higher in the control group. The number of VPB was significantly higher in the triathletes. The increased risk of VPB in the triathlon group is caused by several factors: the degree of cardiac hypertrophy, the increased diastolic reserve, the duration of the exercise, the existence of an aortic insufficiency jet and some specific electrocardiographic findings. CONCLUSIONS: The triathlete has an increased risk of VPB during maximal efforts. We doubt the traditionally accepted view of the physiological nature of those VPB and suspect that the limit of physiological cardiac adaptations to sport efforts is exceeded with the appearance of VPB. The triathlete with VPB and with specific electrocardiographic and echocardiographic findings is a candidate for 'sudden cardiac death'.

Adult↗
PubMed1999

Structural heart adaptations in triathletes.

OBJECTIVE: To perform a triathlon in aerobic conditions, a variety of cardiovascular, haemodynamic and metabolic adaptations are required. The heart is the central concern and also the most important limiting factor. In this study we investigate the structural and functional heart adaptations of a group of triathletes. METHODS AND RESULTS: A group of 52 male triathletes was divided into 4 subgroups in function of their athletic results and compared with a control group of 22 healthy, very active but no athletic men. The groups had comparable anthropometric and general physical characteristics. Very significant differences in cardiac structure and cardiac function were observed between the groups. In the triathletes, we registered distinct signs of significantly mixed eccentric and concentric hypertrophy. Unlike the findings in a pathological left ventricular hypertrophy, the diastolic left ventricular function in triathletes was completely normal and even better than in the control group. The late passive diastolic filling period of the triathlete, in particular, seemed to have specific characteristics. The comparison between the subgroups of triathletes shows us that genetic factors probably play an important role in the cardiac adaptations in triathletes. CONCLUSIONS: In our opinion the "athletic heart" in triathletes is not a specific "physiological entity" but is a transitional phase to a dilated hypertrophic cardiomyopathy. Our study yields some arguments for the following proposition: "People are born as elite athletes, with specific characteristics of the left ventricle and with a specifically supernormal diastolic left ventricular function."

Adaptation, Physiological↗
PubMedDate not supplied

[Drugs, Poverty and HIV: results regarding a provincial needle exchange program in Point de Repères, Quebec].

In this study (n = 200), the characteristics of IDUs participating in a provincial needle exchange program (NEP) for more than 2 years (> 2 years) were compared with those of IDUs having participated for less than 2 years (< or = 2 years). Compared to the < or = 2 years, the > 2 years were more often recipients of welfare (RC: 4.7), especially among the HIV-positive (RC: 62.0); tried quitting drugs more frequently (RC: 3.8); more often recommended the NEP to other IDUs (RC: 3.1); and more often requested being given shelter and longer opening hours (RC: 3.6). These results highlight the urgent need to improve and develop transitional and support services for the > 2 years. Preventive interventions that would reach out to the < or = 2 years where they live should also be implemented in close collaboration with organizations involved in mental health and drug use prevention.

Community Participation↗
PubMedDate not supplied

Importance of determining the percentage body fat in endurance-trained athletes.

A triathlete has to complete a hard endurance effort in aerobic circumstances. This requires important cardiovascular, haemodynamic and metabolic adaptations which alter the percentage body fat. This study included 52 triathletes and 22 control persons. The anthropometric data of the two groups were similar. All the subjects underwent the same extensive non-invasive cardiac exploration with two-dimensional cardiac echo-doppler examination. Maximal incremental exercise tests with determination of lactate and the ventilatory threshold were done on bicycle and on treadmill. Three different methods determined the percentage of body fat: 4 and 12 skin fold method, bioelectrical impedance analysis and dual energy X-ray absorptionmetry. The results showed important structural and functional heart changes in the triathletes. These changes caused distinct heamodynamic adaptations so that the maximal performing capacity and the aerobic capacity could be forced up largely. The haemodynamic adaptations were connected with changes in the percentage body fat in triathletes. The determination of the 12 skin fold measurements enabled us to distinguish the triathletes with better competition results from the inferior triathletes. It is concluded that the method of 12 skin fold measurements gives the most reliable results and requires only a limited instrumentarium. Moreover, this examination can be performed correctly and easily in all circumstances.

Adipose Tissue↗