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Carotid arteriosclerosis in identical twins discordant for cigarette smoking
ranted so that the effect of these agents may eventually evaluated in a controlled clinical trial. Kenneth Ouriel, University
be
MD
of Rochester
Medical
Center
Carotid arteriosclerosis in identica.I for cigarette smoking Haapanen A, Koskenvuo M, Kaprio Heikkila K. Circulation 1989;8: 10-6.
twins
discordant
J, Kesaniemi
YA,
The authors report an in vitro experimental study in which a 20 MHz pulsed Doppler was used to detect flow disturbances and define velocity profiles in a prosthetic conduit under conditions of a steady flow with varying velocities. Both Fast-Fourier transform spectrum analysis and frequency tracking with a demodulator were evaluated for their ability to identify and quantitate flow disturbances and turbulence. To identify the onset of flow disturbances, ensemble averaging was used with spectrum analysis, whereas root mean square fluctuations were used with the frequency tracker. Velocity profiles were calculated from spectrum analysis by use of the Doppler equation. The authors report that the frequency tracking method was preferred for detection and quantitation of flow disturbances because of its ease of use and greater versatility. This technique is intended to be applied to the study of flow disturbances and turbulence in small diameter arterial prostheses, and the authors postulate that these factors are important in the pathogenesis of graft thrombosis. Although the paper is replete with technical detail, the relationship of these flow disturbances to graft thrombosis remains speculative, particularly in this steady flow system. In a pulsatile in vivo flow system with varying outflow resistance and systemic blood pressure, it is likely that the events surrounding graft thrombosis are much more complex and may bear little relation to the presence of minor degrees of flow disturbance in the conduit itself. In addition, the authors have not clearly demonstrated that this research instrument provides any advantage over more widely available commercial Doppler devices, which can be used in vivo. Nevertheless, the article should be of interest to those involved in research to flow mechanics and prosthetic grafts and the ultrasonic detection and quantitation of flow disturbances.
This interesting article has selected a clever method to examine the influence of life-long smoking on the development of carotid arteriosclerosis. The study originated in Finland where the Finnish Twin Cohort compromises all Finnish sex-matched twin pairs born before 1958 and alive in 1967. From 78 identical pairs (61 male and 17 female) with the highest discordance in the life-long dose of cigarette smoking, the authors were able to recruit 49 pairs with a mean age of 52 years. Smoking history was obtained in 1975, 1981, and 1986. The mean life-long smoking dose of the smoking co-twins was 20 pack-years. The smoking and nonsmoking co-twins had similar blood pressures, total plasma cholesterol, body mass index, and psychosocial factors. A significant difference was found in the use of alcohol, which was greater among smoking individuals. Duplex sonography of the carotid arteries was then performed with a 7.5 MHz real-time transducer and a pulsed Doppler. Carotid artery stenosis (narrowing of area of the lumen from 15% to 60%) was found in significantly more smoking twins than nonsmoking co-twins (18% vs 4%). Not only was the total area of carotid plaque larger in smoking co-twins, but the thickness of the inner layer of the carotid arteries was more marked in smoking co-twins. The size of piaques and the degree of inner layer thickening correlated with the dose of smoking but was not statistically significant. The association of smoking with carotid arteriosclerosis was highly significant even after the adjustment for age, total plasma cholesterol level, diastolic blood pressure, and body mass index in multiple logistic regression analyses. The authors emphasize that rhe life-long dose of smoking in the current sample was clearly lower than that of the age- and sex-matched Finnish population. Consequently, they feel that their results probably underestimate the real effect of smoking on carotid arteriosclerosis. The importance of this study lies in its novel method of studying the association of cigarette smoking and carotid arteriosclerosis and in the results that indicate that smoking is a strong factor in the development of carotid atheroma independent of genetic factors.
William M. Blackhar, Jr., MD Univemity of South Florida ColLe8e of Medicine
John W. Hallett, Mayo Clinic
Pulsed Doppler ultrasound system for the measurement of velocity distributions and flow disturbances in arterial prostheses Black RA, How TV. J Biomed Eng 1989;11:35-42.
Jr., MD
be
MD
of Rochester
Medical
Center
Carotid arteriosclerosis in identica.I for cigarette smoking Haapanen A, Koskenvuo M, Kaprio Heikkila K. Circulation 1989;8: 10-6.
twins
discordant
J, Kesaniemi
YA,
The authors report an in vitro experimental study in which a 20 MHz pulsed Doppler was used to detect flow disturbances and define velocity profiles in a prosthetic conduit under conditions of a steady flow with varying velocities. Both Fast-Fourier transform spectrum analysis and frequency tracking with a demodulator were evaluated for their ability to identify and quantitate flow disturbances and turbulence. To identify the onset of flow disturbances, ensemble averaging was used with spectrum analysis, whereas root mean square fluctuations were used with the frequency tracker. Velocity profiles were calculated from spectrum analysis by use of the Doppler equation. The authors report that the frequency tracking method was preferred for detection and quantitation of flow disturbances because of its ease of use and greater versatility. This technique is intended to be applied to the study of flow disturbances and turbulence in small diameter arterial prostheses, and the authors postulate that these factors are important in the pathogenesis of graft thrombosis. Although the paper is replete with technical detail, the relationship of these flow disturbances to graft thrombosis remains speculative, particularly in this steady flow system. In a pulsatile in vivo flow system with varying outflow resistance and systemic blood pressure, it is likely that the events surrounding graft thrombosis are much more complex and may bear little relation to the presence of minor degrees of flow disturbance in the conduit itself. In addition, the authors have not clearly demonstrated that this research instrument provides any advantage over more widely available commercial Doppler devices, which can be used in vivo. Nevertheless, the article should be of interest to those involved in research to flow mechanics and prosthetic grafts and the ultrasonic detection and quantitation of flow disturbances.
This interesting article has selected a clever method to examine the influence of life-long smoking on the development of carotid arteriosclerosis. The study originated in Finland where the Finnish Twin Cohort compromises all Finnish sex-matched twin pairs born before 1958 and alive in 1967. From 78 identical pairs (61 male and 17 female) with the highest discordance in the life-long dose of cigarette smoking, the authors were able to recruit 49 pairs with a mean age of 52 years. Smoking history was obtained in 1975, 1981, and 1986. The mean life-long smoking dose of the smoking co-twins was 20 pack-years. The smoking and nonsmoking co-twins had similar blood pressures, total plasma cholesterol, body mass index, and psychosocial factors. A significant difference was found in the use of alcohol, which was greater among smoking individuals. Duplex sonography of the carotid arteries was then performed with a 7.5 MHz real-time transducer and a pulsed Doppler. Carotid artery stenosis (narrowing of area of the lumen from 15% to 60%) was found in significantly more smoking twins than nonsmoking co-twins (18% vs 4%). Not only was the total area of carotid plaque larger in smoking co-twins, but the thickness of the inner layer of the carotid arteries was more marked in smoking co-twins. The size of piaques and the degree of inner layer thickening correlated with the dose of smoking but was not statistically significant. The association of smoking with carotid arteriosclerosis was highly significant even after the adjustment for age, total plasma cholesterol level, diastolic blood pressure, and body mass index in multiple logistic regression analyses. The authors emphasize that rhe life-long dose of smoking in the current sample was clearly lower than that of the age- and sex-matched Finnish population. Consequently, they feel that their results probably underestimate the real effect of smoking on carotid arteriosclerosis. The importance of this study lies in its novel method of studying the association of cigarette smoking and carotid arteriosclerosis and in the results that indicate that smoking is a strong factor in the development of carotid atheroma independent of genetic factors.
William M. Blackhar, Jr., MD Univemity of South Florida ColLe8e of Medicine
John W. Hallett, Mayo Clinic
Pulsed Doppler ultrasound system for the measurement of velocity distributions and flow disturbances in arterial prostheses Black RA, How TV. J Biomed Eng 1989;11:35-42.
Jr., MD