Brachial Vasoreactivity in Young Adult Smokers
Abstracts
Initial Award Abstract |
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Cigarette smoking has been demonstrated to cause insidious effects on the cardiovascular system. According to the American Heart Association, smoking is a major risk factor for atherosclerosis (thickening of the arteries), heart attack, and stroke. Although such a relationship has been well established, it is only after a major cardiovascular event that smokers realize the consequences of their smoking habit. This is occasioned by the fact that in majority of cases, smokers do not display any cardiovascular symptoms. The onset of symptoms is usually seen in the chronic phase of the disease process, when smoking has already exerted its harmful effects. This indeed is quite unfortunate, taking into account the fact that cardiovascular mortality can be reduced with a concomitant reduction in cigarette smoking.
It is speculated that smoking-induced cardiovascular events can start early on in the life of smokers, as evidenced by an initiation of the development of early atherosclerosis. Unfortunately, the process of early atherosclerosis cannot be observed, because this stage usually involves microscopical changes. The structural changes that are typical of atherosclerosis, i.e. thickening of the arterial walls, are usually seen in the latter part of the disease. Fortunately, the availability of a novel ultrasound method of detecting changes in the endothelial layer of the brachial artery can allow early diagnosis of atherosclerosis development. The present study therefore seeks to elucidate the effects of smoking on the endothelial wall, as well as to validate the utility of this ultrasound method as a diagnostic tool to assess cardiovascular changes in asymptomatic young adult smokers.
Briefly, the study will involve ultrasound assessment of the endothelial function of 75 smokers and 75 non-smokers. The study will be carried out for three years, and cross-sectional and longitudinal changes will be observed. In addition, the role of cytokine factors shall also be determined. It is speculated that cytokines can play a role in promoting the damage that is done to the endothelial wall. Finally, the nutritional profile of the study subjects shall be assessed, taking into account the hypothesis that certain dietary components can exert either a cardioprotective (antioxidants) or damaging (pro-oxidants) role.
The long-term benefits of this study is that this method of detection can play a significant role in determining the cardiovascular risk of young adult smokers who are yet asymptomatic, but already show physiological signs of early atherosclerosis. Knowledge of such information may hopefully promote the realization of smoking cessation benefits among young adult smokers, early on in their smoking habit. |
Final Report |
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Heart disease and stroke start at a relative young age. A very early sign of the negative impact of smoking on the normal healthy vessel wall is its loss of elasticity. We have used a state of the art validated procedure that measures the impact on the level of elasticity in young adult smokers and non-smokers Smoking is very deleterious for the normal inner lining of the vessels. The inner lining is responsible for maintaining a healthy vessel and a certain level of elasticity. After smoking cessation the normalization of the original level of elasticity takes more time than originally anticipated. Our cohort contained a relative high percentage of people of Asian descent. We established that that population seems to be more susceptible to the impact of smoking on the vascular wall. The same finding was established in women as compared with men. Women are suffering earlier and longer from the negative effects of smoking. An unexpected finding was a result of significantly more women than men quitting smoking. The duration that the young adults were smoking favored shorter exposure duration. The accurate measurement method indicated that blood flow measurements were less reliable than the echo/ultrasound findings. This relatively hard to reach group was comfortable in an outpatient environment. Adherence to the protocol, given the difficulties in this age range remained higher than expected in our setting. To summarize the findings of this present study one may say the following:
1. Smoking in young adults has a deleterious effect on the very early phases of the atherosclerotic disease.
2. Smoking has a more lasting impact than originally anticipated on the endothelial dysfunction, the very early phases of disease.
3. The anatomical build up of plaques as measured by carotid Intimal Media Thickness seems to be much more rapid than originally anticipated.
4. The percentage of young adults who quit smoking during this relatively short study when the personalized artery,was shown was much higher than originally anticipated
5. Further studies in larger groups are urgently needed given the fact that at this age of the early twenties definite habits will have been formed (including addictions) that are very difficult to change later on.
Introduction: Smoking has been shown to be an independent cardiovascular risk factor. Complications of smoking include an acceleration of progression of disease, plaque formation, myocardial infarction and stroke. Initially a cardiovascular risk factor inhibits the normal oscillations of the vascular wall resulting in a loss of elasticity and vascular dysfunction. The endothelial dysfunction has been measured by a standardized and validated flow mediated dilation (FMD) of the brachial artery procedure. In addition to the measurement of FMD, Doppler flow measurements were measured by a validated ARTIS® software resulting in quantitative data. In view of the relative small changes that occur during this procedure to measure the impact of smoking on the endothelium and the vascular wall, edge contour detection of at least an area of 0.7 cm is needed. The brachial artery is an ideal vascular bed to study endothelial function and the impact of smoking. The original hypothesis of the study was to assess the extent and severity of endothelial dysfunction in young adult smokers and non-smokers using hyperemia induced FMD procedure. Results: As of January 31, 2001,120 of the originally 151 individuals have returned to our clinic to undergo the procedure, to answer an extensive lifestyle questionnaire and detail the smoking or nonsmoking habits. The participants were given a personalized image of their carotid artery. This picture was explained to every individual.
The scientific results so far have established the following: Smoking is very deleterious for the normal endothelial function. After smoking cessation the normalization of endothelial function takes more time than originally anticipated. Our cohort contained a relative high percentage of people of Asian descent. We established that that population seems to be more susceptible to the impact of smoking on the vascular wall. The same finding was established in women as compared with men. An unexpected finding was the relatively high percentage of people who quit smoking and the fact that significantly more women than men quitting smoking. The duration that the young adults were smoking favored shorter exposure duration. The accurate measurement method indicated that Doppler measurements were less reliable than the B-mode findings. In addition, the ARTIS® edge contour detection technique was superior to the generally used caliper measurement method. This relatively hard to reach group was comfortable in an outpatient environment. Adherence to the protocol, given the difficulties in this age range remained higher than expected in our setting. Further studies in larger cohorts are urgently needed. |
