Effect of cigarette smoking on the pattern of arterial blood flow: possible insight into mechanisms underlying the development of arteriosclerosis

Soluble epoxide hydrolase deletion attenuated nicotine-induced arterial stiffness via limiting the loss of SIRT1

Arterial stiffness, a consequence of smoking, is an underlying risk factor of cardiovascular diseases. Epoxyeicosatrienoic acids (EETs), hydrolyzed by soluble epoxide hydrolase (sEH), have beneficial effects against vascular dysfunction. However, the role of sEH knockout in nicotine-induced arterial stiffness was not characterized. We hypothesized that sEH knockout could prevent nicotine-induced arterial stiffness. In the present study, Ephx2 (the gene encodes sEH enzyme) null (Ephx2^-/-) mice and wild-type (WT) littermate mice were infused with or without nicotine and administered with or without nicotinamide [NAM, sirtuin-1 (SIRT1) inhibitor] simultaneously for 4 wk. Nicotine treatment increased sEH expression and activity in the aortas of WT mice. Nicotine infusion significantly induced vascular remodeling, arterial stiffness, and SIRT1 deactivation in WT mice, which was attenuated in Ephx2 knockout mice (Ephx2^-/- mice) without NAM treatment. However, the arterial protective effects were gone in Ephx2^-/- mice with NAM treatment. In vitro, 11,12-EET treatment attenuated nicotine-induced matrix metalloproteinase 2 (MMP2) upregulation via SIRT1-mediated yes-associated protein (YAP) deacetylation. In conclusion, sEH knockout attenuated nicotine-induced arterial stiffness and vascular remodeling via SIRT1-induced YAP deacetylation.NEW & NOTEWORTHY We presently show that sEH knockout repressed nicotine-induced arterial stiffness and extracellular matrix remodeling via SIRT1-induced YAP deacetylation, which highlights that sEH is a potential therapeutic target in smoking-induced arterial stiffness and vascular remodeling.

Perinatal exposure to maternal smoking and adulthood smoking behaviors in predicting cardiovascular diseases: A prospective cohort study

BACKGROUND AND AIMS

Little is known about the associations between perinatal exposure to maternal smoking and cardiovascular disease (CVD) incidence in offspring, and whether such associations are modified by adulthood and genetically determined smoking behaviors.

METHODS

A total of 414,588 participants without CVD at baseline were included from the UK Biobank in 2006-2010 and followed up through 2018. Cox-proportional hazard models were used to examine the association of perinatal maternal smoking with CVD, and both multiplicative and additive interaction analyses were performed to investigate the modification effects of own smoking behaviors.

RESULTS

During a median follow-up of 8.93 years, we observed 10,860 incident CVD events, including 7006 myocardial infarction (MI) and 4147 stroke. We found that perinatal exposure to maternal smoking was associated with increased risks of CVD (HR: 1.10; 95% CI: 1.05-1.14), MI (1.10; 1.05-1.16) and stroke (1.10; 1.03-1.18). In addition, we observed significant interactions between perinatal exposure to maternal smoking and adulthood exposure to own smoking on CVD and MI on both the multiplicative and additive scales (all p < 0.05). The attributable proportions due to additive interaction between perinatal and adulthood exposure to smoking were 14% (9%-19%) for CVD and 16% (10%-22%) for MI, respectively. Perinatal exposure to maternal smoking also showed an interaction with genetically determined smoking on MI (p < 0.05), but no interactions were found on the total CVD and stroke.

CONCLUSIONS

Our results indicate that perinatal exposure to maternal smoking is associated with increased risks of CVD events, and such relations are modified by adulthood smoking behaviors.

Current Smoking Raises Risk of Incident Hypertension: Hispanic Community Health Study-Study of Latinos

BACKGROUND

Hypertension has been implicated as a smoking-related risk factor for cardiovascular disease but the dose-response relationship is incompletely described. Hispanics, who often have relatively light smoking exposures, have been understudied in this regard.

METHODS

We used data from a 6-year follow-up study of US Hispanic adults aged 18-76 to address the dose-response linking cigarette use with incident hypertension, which was defined by measured blood pressure above 140/90 mm Hg or initiation of antihypertensive medications. Adjustment was performed for potential confounders and mediators, including urinary albumin-to-creatinine ratio which worsened over time among smokers.

RESULTS

Current smoking was associated with incident hypertension, with a threshold effect above 5 cumulative pack-years of smoking (vs. never smokers, hazard ratio for hypertension [95% confidence interval] of 0.95 [0.67, 1.35] for 0-5 pack-years, 1.47 [1.05, 2.06] for 5-10 pack-years, 1.40 [1.00, 1.96] for 10-20 pack-years, and 1.34 [1.09, 1.66] for ≥20 pack-years, P = 0.037). In contrast to current smokers, former smokers did not appear to have increased risk of hypertension, even at the highest cumulative pack-years of past exposure.

CONCLUSIONS

The results confirm that smoking constitutes a hypertension risk factor in Hispanic adults. A relatively modest cumulative dose of smoking, above 5 pack-years of exposure, raises risk of hypertension by over 30%. The increased hypertension risk was confined to current smokers, and did not increase further with higher pack-year levels. The lack of a smoking-hypertension association in former smokers underscores the value of smoking cessation.

Is smoking a risk factor for bleeding in adult men with cerebral arteriovenous malformations? A single-center regression study from China

OBJECTIVE

To assess whether smoking increases the risk of bleeding in patients with cerebral arteriovenous malformations (CAVM).

MATERIAL AND METHODS

According to our research plan, 385 CAVM patients admitted to Beijing Tiantan Hospital from December 2015 to January 2018 were included in this study, including 210 bleeding patients and 175 non-bleeding patients. We divided patients into three subgroups of current smokers, ex-smokers (those who quit smoking for one year or more) and non-smokers. The relationship between smoking and the risk of CAVM rupture was assessed by univariate and multivariate regression analysis.

RESULTS

Multivariate regression analysis showed that there was a statistically significant difference between current smoker and non-smoker (OR = 1.87, p = 0.019). Among the covariates of the multivariate regression analysis, the location, combined with blood flow-related intracranial aneurysms and size were related to the risk of CAVM bleeding.

CONCLUSION

Current smoking may increase the risk of CAVM bleeding; however, there was no significant correlation between ex-smoking and CAVM bleeding.

The role of oxygen transport in atherosclerosis and vascular disease

Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system-the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.

Resting heart rate and the risk of cardiovascular disease, total cancer, and all-cause mortality - A systematic review and dose-response meta-analysis of prospective studies

BACKGROUND AND AIM

Epidemiological studies have reported increased risk of cardiovascular disease, cancer and all-cause mortality with greater resting heart rate, however, the evidence is not consistent. Differences by gender, adjustment for confounding factors, as well as the potential impact of subclinical disease are not clear. A previous meta-analysis missed a large number of studies, and data for atrial fibrillation have not been summarized before. We therefore aimed to clarify these associations in a systematic review and meta-analysis of prospective studies.

METHODS AND RESULTS

PubMed and Embase were searched up to 29 March 2017. Summary RRs and 95% confidence intervals (CIs) were calculated using random effects models. Eighty seven studies were included. The summary RR per 10 beats per minute increase in resting heart rate was 1.07 (95% CI: 1.05-1.10, I² = 61.9%, n = 31) for coronary heart disease, 1.09 (95% CI: 1.00-1.18, I² = 62.3%, n = 5) for sudden cardiac death, 1.18 (95% CI: 1.10-1.27, I² = 74.5%, n = 8) for heart failure, 0.97 (95% CI: 0.92-1.02, I² = 91.4%, n = 9) for atrial fibrillation, 1.06 (95% CI: 1.02-1.10, I² = 59.5%, n = 16) for total stroke, 1.15 (95% CI: 1.11-1.18, I² = 84.3%, n = 35) for cardiovascular disease, 1.14 (95% CI: 1.06-1.23, I² = 90.2%, n = 12) for total cancer, and 1.17 (95% CI: 1.14-1.19, I² = 94.0%, n = 48) for all-cause mortality. There was a positive dose-response relationship for all outcomes except for atrial fibrillation for which there was a J-shaped association.

CONCLUSION

This meta-analysis found an increased risk of coronary heart disease, sudden cardiac death, heart failure, atrial fibrillation, stroke, cardiovascular disease, total cancer and all-cause mortality with greater resting heart rate.

Smoking and atherosclerotic cardiovascular disease: part II: role of cigarette smoking in cardiovascular disease development

Potential mechanisms and biomarkers of atherosclerosis related to cigarette smoking - a modifiable risk factor for that disease - are discussed in this article. These include smoking-associated inflammatory markers, such as leukocytes, high-sensitivity C-reactive protein, serum amyloid A, ICAM-1 and IL-6. Other reviewed markers are indicative for smoking-related impairment of arterial endothelial function (transcapillary leakage of albumin, inhibition of endogenous nitric oxide synthase activity and reduced endothelium-dependent vasodilation) or point to oxidative stress caused by various chemicals (cholesterol oxidation, autoantibodies to oxidized low-density lipoprotein, plasma levels of malondialdehyde and F(2)-isoprostanes and reduced antioxidant capacity). Smoking enhances platelet aggregability, increases blood viscosity and shifts the pro- and antithrombotic balance towards increased coagulability (e.g., fibrinogen, von Willebrand factor, ICAM-1 and P-selectin). Insulin resistance is higher in smokers compared with nonsmokers, and hemoglobin A1c is dose-dependently elevated, as is homocysteine. Smoke exposure may influence the kinetics of markers with different response to transient or chronic changes in cigarette smoking behavior.

Acute and chronic effects of cigarette smoking on arterial stiffness

OBJECTIVES

Pulse wave velocity (PWV) is an indicator of arterial stiffness, especially in the aorta, and a marker for vascular damage. Smoking is reported to increase arterial stiffness. We examined the acute and chronic effects of smoking on arterial stiffness by measuring brachial--ankle PWV (baPWV) using an oscillometric method (VP 1000, Colin Co., Komaki, Japan).

METHODS

All healthy male subjects (chronic smokers, n=40, 30.3 years old vs non-smokers, n=40, 28.3 years old) smoked two cigarettes (nicotine 1.5 mg) within 10 min and measured blood pressure (BP), heart rate and baPWV at baseline, 5, 15, 30, 45 and 60 min and compared with controls (n=20, 29.3 years old).

RESULTS

Systolic BP was higher in chronic smokers than non-smokers or controls. Smoking increased the systolic and diastolic BP and heart rate significantly at 5 min in both chronic smokers and non-smokers as compared with baseline levels or controls (respectively, p<0.001) and returned to baseline level at 15 min. Pulse pressure did not increase significantly. baPWV increased significantly in both chronic smokers and non-smokers at 5 min (12.1--17.3 m/s vs 11.1--12.7 m/sec, respectively) and remained higher for 30 min compared with controls (p<0.001). Smoking increased baPWV to a greater extent in chronic smokers than in non-smokers (p<0.01).

CONCLUSION

Acutely, cigarette smoking increased BP, heart rate and baPWV in chronic smokers and non-smokers. These effects were more prominent in chronic smokers than in non-smokers. These findings suggest that cigarette smoking have deleterious effects on cardiovascular system by stiffening arteries.

Arterial geometry, flow pattern, wall shear and mass transport: potential physiological significance

We have studied numerically steady and unsteady flow in a straight and a helically stented common carotid artery, in order to model porcine experimental results that show reduced intimal hyperplasia (IH) in the helical case. The combination of flow pulsatility and three-dimensionality generates a sweeping motion of the Dean vortices, which overall reduced extremes of both oxygen flux to the vessel wall and wall shear stress (WSS). Since IH and atherosclerosis affect preferentially low WSS regions, these findings imply that vessel three-dimensionality and flow pulsatility can play important protective roles in respect of these diseases. The amplitude and frequency of the velocity waveform are important parameters of the system. Increase in amplitude increases WSS and oxygen flux to the vessel wall. Increase in frequency has a small effect; it increases WSS but has no effect on the oxygen flux to the vessel wall.

Heart rate and mortality from cardiovascular causes: a 12 year follow-up study of 379,843 men and women aged 40-45 years

AIM

To study the relationship between heart rate and (a) all deaths and (b) cardiovascular deaths in a large cohort of middle-aged Norwegian men and women.

METHODS AND RESULTS

A prospective study of participants in cardiovascular surveys that were carried out in 1985-1999 and covered men and women aged 40-45 years in all counties except the capital, Oslo. In total, 180,353 men and 199,490 women aged 40-45 years without cardiovascular history or diabetes accrued 4 775 683 years of follow-up. There was a positive and graded association between heart rate and mortality from all causes, as well as between heart rate and deaths from cardiovascular disease (CVD), ischaemic heart disease, and stroke. However, these associations were greatly reduced when we adjusted for the main risk factors of disease. The hazard ratios for any death were reduced from 3.14 to 1.82 for men (95% CI, 1.62-2.04) and from 2.14 to 1.37 for women (95% CI, 1.19-1.59), when we compared > or =95 b.p.m. with <65 b.p.m. The corresponding figures for CVD were a reduction from 4.79 to 1.51 for men (95% CI, 1.21-1.87) and from 2.68 to 0.78 for women (95% CI, 0.53-1.15).

CONCLUSION

In this cohort of middle-aged men and women, a crude association between heart rate and death from CVDs was greatly weakened when we adjusted for the main risk factors of disease. This suggests that an increased heart rate in middle age may be a marker of high cardiovascular risk, but is not an independent risk factor.

Doppler ultrasound evaluation of facial transverse and infraorbital arteries: influence of smoking and aging process

BACKGROUND

Plastic surgeons are always concerned about integrity of facial vascularization in smokers and elderly candidates for face-lifting. Using Doppler ultrasound, this study aimed to evaluate influence of chronic smoking and aging on facial transverse and infraorbital artery blood flow.

METHODS

For this study, 40 healthy volunteer women were submitted to bilateral Doppler ultrasound of facial transverse and infraorbital arteries. Volunteers were divided into three groups: group 1 (13 nonsmoking women ages 18-33 years), group 2 (13 nonsmoking women ages 55-70 years), and group 3 (14 smoking women ages 55-70 years). Blood flow parameters measured were peak systolic velocity, end-diastolic velocity, resistivity index, and pulsatility index.

RESULTS

Chronic smoking did not cause statistically significant alterations in peak systolic velocity in any of the arteries. However, there was a significant augmentation of end-diastolic velocity and a reduction in resistivity and pulsatility index in both arteries. Aging process did not significantly alter any of the parameters evaluated. Findings in both sides of the face were similar for both arteries.

CONCLUSIONS

Chronic smoking significantly altered end-diastolic velocity, resistivity, and pulsatility index in regional arterial circulation of the face. Aging process, however, did not significantly influence any of blood flow parameters studied.

Longitudinal diastolic myocardial functions are affected by chronic smoking in young healthy people: a study of color tissue Doppler imaging

AIMS

Many cardiac and hemodynamic alterations occur after acute consumption of cigarettes. The aim of this study is to evaluate the effect of chronic smoking on longitudinal myocardial functions of left ventricle in young, healthy people by using color tissue Doppler imaging modalities.

METHODS AND RESULTS

Ninety-nine healthy participants were studied. There were 65 smokers and 34 nonsmokers. All subjects were between 20 and 35 years old. Sample volumes were placed on the mid left ventricle in the inner half of the myocardium at the septum, lateral, inferior, and anterior walls. The peak systolic strain (S-S), peak systolic strain rate (S-SR), peak early diastolic SR (E-SR), peak late diastolic SR (A-SR), peak systolic tissue velocity (S-TV), peak early diastolic TV (E-TV), and peak late diastolic TV (A-TV) values were measured. For the systolic parameters S-S, S-SR, and S-TV values were not different between the groups. For the diastolic parameters smokers had lower E-SR and E-TV values than nonsmokers (P = 0.03 for both). Although there was a trend toward higher A-SR and A-TV values in the smokers, they were not reaching the statistical significance.

CONCLUSION

Chronic smoking in young, healthy people causes significant alterations in the longitudinal diastolic myocardial function parameters as assessed by color tissue Doppler imaging.

Factors affecting endometrial and subendometrial blood flow measured by three-dimensional power Doppler ultrasound during IVF treatment

BACKGROUND

No information exists in the literature regarding the factors affecting the blood flow towards the endometrial and subendometrial regions during IVF treatment.

METHODS

We examined the effect of women's age, their smoking habits, their type of infertility (i.e. primary or secondary) and parity, causes of infertility and serum estradiol (E2) concentration on endometrial and subendometrial blood flows as measured by a three-dimensional (3D) power Doppler ultrasound during IVF treatment. All patients received a standard long protocol of ovarian stimulation and serum E2 concentration was determined on the day of hCG. 3D ultrasound examination with power Doppler was performed on the day of oocyte collection to determine vascularization index (VI), flow index (FI) and vascularization flow index (VFI) of endometrial and subendometrial regions.

RESULTS

The age of women, their smoking habits, their types of infertility and parity and causes of infertility had no effect on the endometrial and subendometrial 3D power Doppler flow indices. There was a negative correlation between serum E(2) concentration and endometrial FI (r = -0.109; P = 0.006).

CONCLUSIONS

Endometrial blood flow in IVF treatment was negatively affected by serum E2 concentration only.

Cross-linking of glycated collagen in the pathogenesis of arterial and myocardial stiffening of aging and diabetes

The normal aging process is often accompanied by arterial wall stiffening and by a decrease in myocardial compliance. These processes contribute to isolated systolic hypertension and diastolic heart failure, which lead to substantial morbidity and mortality among older individuals. Patients with diabetes manifest arterial stiffening and diastolic dysfunction at a younger age. This leads to the concept that the mechanism that underlies changes in vascular mechanical properties during aging is accelerated in diabetes. The Maillard reaction or advanced glycation of proteins occurs slowly in vivo with normal aging and at an accelerated rate in diabetes. Advanced glycation end-products (AGEs) that form during the Maillard reaction are implicated in the complications of aging and diabetes. The formation of AGEs on vascular wall and myocardial collagen causes cross-linking of collagen molecules to each other. This leads to the loss of collagen elasticity, and subsequently a reduction in arterial and myocardial compliance. Aminoguanidine, an inhibitor of AGE formation, is effective in slowing or preventing arterial stiffening and myocardial diastolic dysfunction in aging and diabetic animals. In aged and diabetic animals, agents that can chemically break pre-existing cross-linking of collagen molecules are capable of reverting indices of vascular and myocardial compliance to levels seen in younger or non-diabetic animals. These studies suggest that collagen cross-linking is a major mechanism that governs aging and diabetes-associated loss of vascular and cardiac compliance. The development of AGEs cross-link breakers may have important role for future therapy of isolated systolic hypertension and diastolic heart failure in these conditions.

Late systolic wave on brachial artery blood flow velocity pattern in patients with coronary artery disease and its relation to vascular stiffness

Duplex-Doppler study typically exhibits triphasic brachial artery blood flow velocity pattern in subjects classified as normal without clinically evident atherosclerotic complications, heart disease, hypertension, or diabetes mellitus. In this study, the authors described the late systolic wave on the brachial artery blood flow velocity pattern in patients with coronary artery disease and investigated the relation between late systolic wave and vascular stiffness. Blood flow profile and velocity of the brachial artery were determined noninvasively by ultrasound pulsed-Doppler technique under the guidance of a B-mode ultrasound image in 96 patients with coronary artery disease (CAD). The control group consisted of 23 healthy subjects with no or maximally 2 risk factors (only among age, cigarette smoking, obesity, and gender) for vascular disease. None of the patients and controls had clinical evidence of arterial disorders at upper extremities. In 32 patients (33%) with CAD, a late systolic wave was observed in the brachial artery Doppler study. On the other hand, no late systolic wave was observed in the healthy subjects. In addition, multivessel disease, hypertension, advanced age, diabetes, and smoking were significantly more frequent in patients with the late systolic wave. In conclusion, peripheral arterial abnormalities induced by vascular stiffness may produce alterations in regional wave reflections, and the normal triphasic pattern of the brachial artery blood flow may change by the appearance of the late systolic wave.

Vascular damage from smoking: disease mechanisms at the arterial wall

The products of tobacco combustion are absorbed into the systemic circulation. Absorbed nicotine stimulates the release of catecholamines, whilst other products (perhaps including nicotine) injure the arterial endothelium and promote atherogenesis. Free radicals and aromatic compounds diminish the endothelial synthesis of nitric oxide, causing impaired endothelium-dependent relaxation of arteries, the earliest clinical sign of endothelial dysfunction. Smoking alters the shear forces and rheology at the endothelial surface and these changes enhance the effects of products of tobacco combustion to upregulate leucocyte adhesion molecules on the endothelial surface. The increased oxidation of low density lipoprotein (LDL) in smokers has synergistic effects to promote monocyte adhesion and monocyte migration into the subintimal space. Continued stimulation of intimal cells by oxidized LDL leads to the development of atherosclerosis. Many of these effects are ameliorated by high concentrations of vitamin C. Smoking also potentiates thrombosis at the dysfunctional endothelium by increasing the concentration of plasma fibrinogen and altering the activity of platelets. All these proatherogenic effects of smoking to injure the endothelium also are observed, albeit to lesser extent, in passive smokers.

Cardiovascular toxicity of nicotine: implications for nicotine replacement therapy

This review discusses the known cardiovascular effects of smoking and the effects of nicotine without tobacco smoke and interprets the available data on cardiovascular risk during nicotine replacement therapy (NRT). Nicotine gum and patches are now approved for over the counter sale in the United States. Smokers with cardiovascular disease are advised to seek physician counseling before using nicotine products, but information regarding the safety of these products in such patients is not readily available to most physicians. Nicotine may contribute to cardiovascular disease, presumably by hemodynamic consequences of sympathetic neural stimulation and systemic catecholamine release. However, there are many potential cardiovascular toxins in cigarette smoke other than nicotine. The doses of nicotine obtained by regular cigarette smoking generally exceed those delivered by NRTs, and the cardiovascular effects of nicotine are, in general, more intense when delivered rapidly by cigarette smoking than the slower delivery by transdermal nicotine or nicotine gum. Because the dose-cardiovascular response relation for nicotine is flat, the effects of cigarette smoking in conjunction with NRT are similar to those of cigarette smoking alone. Cigarette smoking increases blood coagulability, a major risk factor for acute cardiovascular events, whereas transdermal nicotine does not appear to do so. Clinical trials of NRT in patients with underlying, stable coronary disease suggest that nicotine does not increase cardiovascular risk. At worst, the risks of NRT are no more than those of cigarette smoking. The risks of NRT for smokers, even for those with underlying cardiovascular disease, are small and are substantially outweighed by the potential benefits of smoking cessation.

Vascular abnormalities associated with long-term cigarette smoking identified by arterial waveform analysis

PURPOSE

Consistent changes in the arterial pulse contour are found with aging and disease states that impair the compliance characteristics of blood vessels that buffer pulsatile phenomena in the arterial tree. We assessed whether vascular adaptation in structure or tone of blood vessels associated with long-term cigarette smoking would influence steady state or pulsatile hemodynamics at a preclinical stage.

PATIENTS AND METHODS

We analyzed intraarterial brachial artery waveforms in 35 healthy long-term cigarette smokers and 32 nonsmoking control subjects matched for age and gender. The diastolic pressure decay was segmented into two components: an exponential decay that reflects the compliance characteristics of the large arteries and an oscillatory diastolic waveform generated principally by pulse-wave reflections from small arteries and arterioles.

RESULTS

Resting heart rate was higher in smokers than nonsmokers, mean +/- SD (66 +/- 9 versus 60 +/- 10; P < 0.05). Systolic, diastolic, and mean arterial pressures were lower in smokers compared with nonsmokers (P < 0.01 for all). No differences in cardiac output, large artery compliance, or systemic vascular resistance estimates where apparent between groups. A decrease in the amplitude and duration of the diastolic wave, produced by peripheral pulse-wave reflections in the arterial system, was found in smokers compared with nonsmokers (0.04 +/- 0.02 versus 0.7 +/- 0.03; P < 0.001).

CONCLUSIONS

Quantitative changes in the arterial waveform were found in long-term smokers compared with nonsmoking control subjects. The altered arterial wave shape marks the presence of abnormal structure or tone in the peripheral vasculature that affects pulsatile arterial function. This measure of vascular injury is detectable at a preclinical stage and may relate to the subsequent risk of morbid events in chronic smokers and aid in clinical risk stratification.

Pencil excitation with interleaved fourier velocity encoding: NMR measurement of aortic distensibility

A technique is presented for rapidly and noninvasively determining aortic distensibility, by NMR measurement of pulse-wave velocity in the aorta. A cylinder of magnetization is excited along the aorta, with Fourier-velocity encoding and readout gradients applied along the cylinder axis. Cardiac gating and data interleaving improve the effective time resolution to as high as 3 ms. Wave velocities are determined from the position of the foot of the flow wave in the velocity profiles. Evidence of helical flow distal to the aortic arch can be seen in normal subjects, while disturbed flow patterns are visible in patients with aneurysms and dissections.

Cardiac function in smokers and nonsmokers: the CARDIA study. The Coronary Artery Risk Development in Young Adults Study

OBJECTIVES

This study assessed clinical and echocardiographic measures of cardiac function at rest in smokers and nonsmokers to determine the associations of cigarette smoking with various measures of left and right ventricular performance.

BACKGROUND

Whereas the immediate cardiovascular effects of cigarette smoking have been well described, the long-term effects in an otherwise healthy cohort have not. Of particular interest were associations with heart rate, left ventricular end-systolic stress and left ventricular mass because higher levels of these measures would suggest increased myocardial oxygen consumption.

METHODS

In year 5 of the Coronary Artery Risk Development in Young Adults (CARDIA) study, 3,366 smokers and nonsmokers (ex-smokers were excluded) underwent echocardiography as well as assessment of heart rate, anthropometric measurements and blood pressure. Participants ranged in age from 23 to 35 years and were equally distributed by race and gender. Echocardiographic measures included pulsed Doppler pulmonary artery acceleration time (a decrease suggests increased pulmonary artery pressure), left ventricular mass, left ventricular end-systolic stress and left ventricular fractional shortening.

RESULTS

All comparisons were between smokers and nonsmokers. Heart rate at rest was significantly higher in smokers by 1.5 to 5 beats/min in all race/gender groups except black men. In men who smoked, pulmonary artery acceleration time was significantly lower by 4 to 8 ms. Except for black male smokers, there was a trend toward increased left ventricular mass (3 to 8 g) in all race/gender groups, significant in black women. Left ventricular end-systolic stress was significantly higher in women who smoked (4 to 6 dynes/cm2). There were no differences for systolic blood pressure or left ventricular fractional shortening.

CONCLUSION

In an assessment of cardiovascular function at rest in young adults, quantifiable differences between smokers and nonsmokers that predict increased rest myocardial oxygen consumption in smokers were found. Some of these differences were gender specific.

Relation of smoking with carotid artery wall thickness and stenosis in older adults. The Cardiovascular Health Study. The Cardiovascular Health Study (CHS) Collaborative Research Group

BACKGROUND

Cigarette smoking has been associated with increased risk of atherosclerotic diseases in hospital-based studies and in studies of middle-aged populations but not in population-based studies of older adults with and without clinical cardiovascular disease.

METHODS AND RESULTS

We investigated the relation of smoking to carotid artery atherosclerotic disease, expressed as intimal-medial wall thickness and arterial lumen narrowing (stenosis) measured by ultrasound. Subjects were 5116 older adults participating in the baseline examination of the Cardiovascular Health Study, a community-based study of cardiovascular diseases in older age. With increased smoking there was significantly greater internal and common carotid wall thickening and internal carotid stenosis: current smokers > former smokers > never-smokers; for instance, the unadjusted percent stenosis was 24%, 20%, and 16%, respectively (P < .0001). A significant dose-response relation was seen with pack-years of smoking. These findings persisted after adjusting for other cardiovascular risk factors and were also confirmed when analyses were restricted to those without prevalent cardiovascular disease. The difference in internal carotid wall thickness between current smokers and nonsmokers was greater than the difference associated with 10 years of age among never-smoking participants (0.39 mm versus 0.31 mm). Among all participants, the prevalence of clinically significant (> or = 50%) internal carotid stenosis increased from 4.4% in never-smokers to 7.3% in former smokers to 9.5% in current smokers (P < .0001).

CONCLUSIONS

These findings extend previous reports of a positive relation between smoking and carotid artery disease to a population-based sample of older adults using several different indicators of atherosclerotic disease.

Magnetic resonance angiography: today and tomorrow

Magnetic resonance angiography (MRA) has enjoyed enthusiastic success at many research institutions where it is now routinely used in place of invasive x-ray angiography (XRA) for a variety of applications. While the physical principles of MRA are well understood, there is still plenty of opportunity for growth in the coming years. Recent improvements in instrumentation have permitted more rapid acquisition and manipulation of larger data sets. Instruments in the future are sure to continue this trend as computer hardware becomes more capable and less expensive. New clinical applications will also expand the utility of MRA beyond its current use. MRA is already being used in peripheral vessels and it appears to have great potential in the abdomen. Research into MRA methods for coronary vessel imaging is also beginning to show intriguing results. In addition, preliminary research results suggest that interventional MRA may one day become a reality.

Noninvasive determination of local wavespeed and distensibility of the femoral artery by comb-excited Fourier velocity-encoded magnetic resonance imaging: measurements on athletic and nonathletic human subjects

The local distensibility of arteries is of interest because distensibility varies from artery to artery, may be altered by disease to different extents in different arteries, and may be modified by physiological or pharmacological means. Using magnetic resonance imaging (MRI) we have measured local arterial wavespeed in the femoral artery in healthy human subjects and calculated local arterial distensibility. We acquired 2-D coronal and sagittal MR phase contrast angiograms of the femoral artery. We used a novel imaging technique, comb-excited Fourier velocity-encoded MRI, to obtain simultaneous measurements of arterial blood velocity at two stations 14 cm apart on the femoral artery. The separation of the two stations divided by the delay between the onset of forward flow at the two stations was used to calculate the wavespeed. The measurements were made on 16 healthy men (8 athletes, 8 non-athletes) in the age range 20-30 years, who were scanned with the use of ECG gating and an extremity coil in a 1.5 Tesla scanner (GE Medical Systems, Milwaukee, WI). By systematically altering the delay between the R-wave and data acquisition, a temporal resolution of 2-4 ms was achieved. The onset of forward flow at each station was determined from a least-squares fit to the data for 30% of the maximum velocity during the cardiac cycle. Average femoral artery wavespeed was 7.7 m/s +/- 1.2 in the athletes and 11.5 m/s +/- 1.1 in the non-athletes (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

A one-dimensional velocity technique for NMR measurement of aortic distensibility

A technique is presented for rapidly and noninvasively determining aortic distensibility, by NMR measurement of wave velocity in the aorta. A two-dimensional NMR selective-excitation pulse is used to repeatedly excite a cylinder of magnetization in the aorta, with magnetization read out along the cylinder axis each time. A toggled bipolar flow-encoding pulse is applied prior to readout, to produce a non-dimensional phase-contrast flow image. Cardiac gating and data interleaving are employed to improve the effective time resolution to 2 ms. Wave velocities are determined from the slope of the leading edge of flow measured on the resulting M-mode velocity image. The technique is sensitive over a range of distensibilities from 10(-6) to 10(-3) m s2/kg. The average value in the descending thoracic aorta in seven normal subjects was found to be 4.8 x 10(-5) m s2/kg, with a significant inverse correlation with age.

Short- and long-term effects of smoking on arterial wall properties in habitual smokers

OBJECTIVES

This study investigated the short-term effects of smoking on hemodynamic function and distensibility and compliance of large arteries in habitual smokers. In addition, the effect of smoking was not measured in nonsmokers, but vessel wall properties were compared between smokers and nonsmokers (basal state).

BACKGROUND

Smoking is a well known risk factor for atherosclerosis. Loss of distensibility and compliance of large arteries may play a role in the onset of atherosclerosis.

METHODS

The distensibility and compliance coefficients of the common carotid and brachial arteries were determined from the arterial wall displacement during systole and the end-diastolic diameter by using a vessel wall movement detector and from the pulse pressure as assessed in the upper arm. Cardiac function (cardiac output, stroke volume) was measured with Doppler echocardiography. Systemic vascular resistance was calculated as mean arterial pressure divided by cardiac output.

RESULTS

In habitual smokers, smoking one cigarette caused a sharp increase in blood pressure (6%) and heart rate (14%). Cardiac index increased (16%), mainly because of the marked increase in heart rate. Stroke and systemic vascular resistance indexes did not change significantly. Smoking enhanced forearm blood flow after wrist occlusion (17%), but total forearm blood flow was unchanged, suggesting an increase in muscle blood flow and a decrease in skin flow. Because of higher blood pressure, the diameter of the elastic common carotid artery increased by 3% (passive phenomenon). Distensibility of the carotid artery decreased (7%), and as a result, carotid compliance was preserved. In contrast, despite higher blood pressure, the diameter of the muscular brachial artery did not change, suggesting an increased vascular tone. Brachial distensibility and compliance decreased (18% and 19%, respectively). Habitual smokers were comparable to nonsmokers with regard to blood pressure, cardiac function, vascular resistance and vessel wall properties of large arteries. Heart rate was higher in habitual smokers (14%).

CONCLUSIONS

These data indicate that in habitual smokers, smoking one cigarette causes short-term increases in arterial wall stiffness that might be harmful to the artery and increase the risk for plaque rupture. Except for a higher heart rate, no obvious long-term effect of smoking was observed on hemodynamic variables and arterial stiffness. Because acute cardiovascular events are mainly due to plaque rupture, the short-term effects of smoking might be a more important risk than long-term effects for these acute ischemic events.

Chronic and acute effects of cigarette smoking on skin blood flow

A laser Doppler flowmeter was used to assess blood flow changes in habitual smokers, as compared with nonsmokers, where members of both groups were young and healthy. Acute and chronic effects of cigarette smoking were measured by using the cutaneous postischemic reactive hyperemia test. Basic flow was recorded in four sites: forehead, postauricular, forearm, and finger. Recovery time from reactive hyperemia was longer in habitual smokers than in nonsmokers. Peak flow during reactive hyperemia was significantly lower after smoking. Basic blood flow during smoking did not show significant variation in the sites tested. The authors conclude that skin microvasculature is influenced by acute and chronic effects of cigarette smoking in young subjects; they discuss some of the possible mechanisms and their implications.

The role of cold in ischaemic heart disease: a review

A review of the literature suggests that the geographical and social class distribution of ischaemic heart disease (IHD) could be partly explained by variations in degrees of cold exposure, which includes wind and rain as well as temperature, with frequent exposure to cold being more harmful than steady exposure. Blood pressure (BP) and serum cholesterol are raised in response to acute and chronic exposure to cold. Smoking and cold produce similar physiological changes which increase the risk of IHD, while regular exercise blunts the physiological effects of cold and other stresses. There are many acute responses to cold which could trigger a myocardial infarction (MI) and therefore cold is probably a major precipitating factor in many cases of MI. Public health measures to improve domestic housing and the working environment may produce a significant impact on the incidence of IHD.

Ischemic gastroparesis: resolution after revascularization

Patients with chronic nausea and vomiting frequently present challenging diagnostic and therapeutic problems. In such patients, gastroparesis of unknown cause, or "idiopathic" gastroparesis, may be the only objective finding. Two middle-aged women with nausea, vomiting, and weight loss of 10 and 26 kg over 6 and 18 months, respectively, were evaluated. Routine laboratory and barium study results were normal. Solid-phase gastric emptying studies showed severe gastroparesis in both patients. Upper endoscopies excluded gastric outlet obstruction. Gastric dysrhythmias (4-cpm and 1-cpm patterns) were recorded using cutaneous electrodes. An abdominal bruit was ascultated in one patient. Abdominal arteriograms in both patients showed total occlusion of all three major mesenteric vessels with collaterals supplied via hemorrhoidal arteries. Bypass grafting procedures of the celiac and superior mesenteric arteries in one patient and of the celiac artery in the other patient were performed. Six months after mesenteric artery revascularization, upper gastrointestinal symptoms had resolved and original weights were regained. Furthermore, normal 3-cpm gastric myoelectrical activity and normal gastric emptying of solids were restored in both patients. In these patients, chronic mesenteric ischemia resulted in a novel and reversible cause of gastroparesis, gastric dysrhythmias, and accompanying symptoms.

In vitro study of the influence of radial wall motion on wall shear stress in an elastic tube model of the aorta

The purpose of this study was to determine the influence of radial motion of an arterial wall on the shear stress that flowing blood imposes on the wall (wall shear stress). Wall shear stress is known to influence endothelial cell function and may play a role in atherogenesis, but its magnitude and distribution in the circulation are not well understood. To simulate arterial wall motion, we used both straight and curved rubber tubing models in a mock circulatory system incorporating a variable impedance element distal to the model aorta. Wall shear rate was measured with a hot-film anemometer probe mounted flush on the tubing wall and free to move with the wall. Wall shear stress was determined as the product of wall shear rate and viscosity. By changing the distal impedance element, we determined the influence of the (temporal) phase angle between pressure and flow, or equivalently, tube diameter and flow, on wall shear stress. We observed a fivefold increase in peak wall shear stress and the onset of intense wall shear stress reversal sinusoidal flows as the phase angle between pressure and flow was reduced from -60 degrees to -80 degrees. Wall shear stresses were insensitive to this same phase angle when its value was between -10 degrees and -60 degrees. Theoretical predictions, also presented here, are in accord with these observations. The phenomena we have observed in elastic tubes may be important in the arterial system because the phase angle between the first harmonic of pressure and flow in the aorta of humans is usually near our sensitive range. This same phase angle becomes more negative in hypertensive patients and is influenced by vasoactive drugs.

Cardiovascular effects of nicotine during physical activity and following meal consumption

1. In two separate studies using healthy male smokers as subjects, the acute cardiovascular effects of a measured dose of nicotine (15 micrograms/kg) were examined in conjunction with light physical activity and following consumption of a meal, conditions typical of nicotine intake via smoking. 2. Increases in heart rate and systolic blood pressure attributable to nicotine were similar during rest, physical activity, and following eating, demonstrating additivity with the cardiovascular effects of activity and a caloric load. Diastolic blood pressure was less affected by nicotine. 3. These results indicate that cardiovascular activity is acutely increased following nicotine (smoking) regardless of other influences on the cardiovascular system. Such effects may help explain increased risks of acute cardiac abnormalities due to smoking.

Smoking, calcium, calcium antagonists, and aging

Aging is characterized, besides other changes, by a progressive increase in calcium content in the arterial wall, which is enhanced by diabetes mellitus, osteoporosis, arterial hypertension, and tabagism. As to tabagism, experiments in animals have shown that nicotine can increase calcium content of the arterial wall, and clinical studies have demonstrated that cigarette smoking induces peripheral vasoconstriction, with consequent increase in blood pressure levels. In order to study the role of calcium ions in the pathogenesis of the vasoconstrictive lesions caused by "acute" smoking, the author has studied the peripheral vascular effects of the calcium-channel antagonist nifedipine, a dihydropyridine derivative, and calcitonin, a hypocalcemizing hormone which possess vasoactive actions on 12 elderly regular smokers (mean age 65.8 years). The results demonstrated that both nifedipine (10 mg sublingually 20 min before smoking) and salmon calcitonin (100 MRC U/daily intramuscularly for three days) are able to prevent peripheral vasoconstriction evaluated by Doppler velocimetry, as well as the increase of blood pressure induced by smoking. On the basis of our results, the author proposes that cigarette smoking-induced vasoconstriction is a calcium-mediated process, which can be hindered by drugs with calcium antagonist action.

Plasma fibrinogen and coronary risk factors: the Scottish Heart Health Study

Plasma fibrinogen was measured in a sample of 8824 men and women aged 40-59 years participating in the Scottish Heart Health Study, and related to cardiovascular risk factors. Women had higher fibrinogen levels than men. In both sexes, multivariate analysis showed that fibrinogen was positively associated with age, smoking, total cholesterol and body mass index and negatively associated with alcohol consumption. Among women, early menopause and systolic blood pressure were also associated with fibrinogen levels. Univariate analyses showed weak positive associations with fish consumption for both sexes although only male white fish consumption entered the final model. Women with a history of contraceptive pill usage had significantly lower fibrinogen levels. The relationship between fibrinogen and physical activity was complex, and could largely be explained by smoking. These findings support the hypothesis that raised fibrinogen is one mechanism by which several major risk factors may promote coronary heart disease. However, known risk factors explained, at most, 10% of the total variance in fibrinogen levels among the general population.

Peripheral haemodynamic effects of smoking in habitual smokers. A methodological study

The effect of smoking on forearm haemodynamics was studied in four groups of healthy subjects, who had all smoked cigarettes (10-15 cigarettes/day) on average for 10 years. Changes in heart rate, blood pressure, forearm blood flow, forearm vascular resistance and pulse wave velocity were determined before and every 15 min for 75 min after smoking two cigarettes within 10 min. The inhaled nicotine was about 2.2 mg. There was no significant difference between the four groups in any haemodynamic variable before or after smoking, which indicated adequate reproducibility of the parameters studied and so made it possible to pool the results from all 30 subjects. Smoking significantly increased blood pressure, heart rate and pulse wave velocity and decreased forearm blood flow. Forearm vascular resistance remained unchanged. The rises in systolic blood pressure and pulse wave velocity were transient and both peaked (7% and 28%, respectively) 15 min after smoking. In contrast, heart rate and diastolic blood pressure remained significantly elevated and forearm blood flow was significantly decreased throughout the 75 min follow-up. The maximal changes were: heart rate +34%, diastolic blood pressure +17%, and forearm blood flow -24%. It is concluded that smoking produces statistically significant changes in forearm haemodynamics affecting both small and large arteries. The reproducibility of the study design means that it can be used to evaluate substances which may antagonize the haemodynamic effects of tobacco smoking.

Change in cough reflex after treatment with enalapril and ramipril

OBJECTIVE

To find out whether enalapril or ramipril causes the sensitivity of the cough reflex to change or symptomatic cough to develop in patients with hypertension.

DESIGN

Prospective, placebo controlled, double blind, randomised crossover study.

SETTING

Academic units of clinical pharmacology and medicine.

PATIENTS

20 Patients (nine men and 11 women) who needed to take angiotensin converting enzyme inhibitors to control hypertension.

INTERVENTIONS

All patients received enalapril 10 mg daily, ramipril 10 mg daily, or placebo daily for one week in random order, with a washout period of at least one week between treatments. For assessment of sensitivity of the cough reflex the patients inhaled various concentrations of capsaicin solution in random order.

MAIN OUTCOME MEASURES

Measurement of the doses of capsaicin required to cause two or more and five or more coughs or the development of a symptomatic cough.

RESULTS

Blood pressure, symptoms of cough, and the sensitivity of the cough reflex to inhaled capsaicin were recorded at the start of the study and before and at the end of each treatment period. Plasma urea and creatinine concentrations and angiotensin converting enzyme activity were measured at the start of the study and the end of each treatment period. Data were analysed by two way analysis of variance. Mean blood pressure was 159/97 mm Hg at the start of the study and 152/92, 143/88, and 147/86 mm Hg after treatment with placebo, enalapril, and ramipril respectively. Mean (SE) plasma angiotensin converting enzyme activity was 2.2 (0.2) mmol/l/h after treatment with placebo and fell significantly to 1.3 (0.1) mmol/l/h and to 0.4 (0.1) mmol/l/h after treatment with enalapril and ramipril respectively. No patient complained of cough while taking placebo but three women complained of cough when taking both enalapril and ramipril. The mean (95% confidence interval) lowest dose of capsaicin causing two or more coughs was 2.4 (1.5 to 4.0), 1.8 (1.12 to 2.82), and 2.2 (1.7 to 3.0) nmol after treatment with placebo, enalapril, and ramipril respectively; none of these changes were significant. The lowest dose of capsaicin causing five or more coughs was 18.9 (13.9 to 25.8), 14.4 (8.4 to 24.5), and 15.3 (10.8 to 21.2) nmol respectively; none of these changes were significant. The three patients who complained of cough had normal sensitivity to capsaicin after treatment with placebo but had a considerably increased sensitivity after treatment with enalapril and ramipril.

CONCLUSIONS

Both enalapril and ramipril increase the sensitivity of the cough reflex appreciably in patients who complain of cough during treatment, but they do not change the se

Carotid arteriosclerosis in identical twins discordant for cigarette smoking

From a nationwide twin panel, identical twin pairs with highest discordance in cigarette smoking were selected for a study of arteriosclerosis (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 cotwins was 20 package-years. The smoking and nonsmoking cotwins had similar systolic and diastolic blood pressures, total plasma cholesterol level, body mass index, and some psychosocial factors; the only difference was found in use of alcohol, which was greater among smoking cotwins. Duplex sonography of carotid arteries was performed. Carotid artery stenoses (narrowing of area of the lumen with 15-60%) were found in nine pairs: in nine smoking twins and in two of their nonsmoking cotwins (p = 0.036). The total area of carotid plaques was 3.2 times larger in smoking cotwins (p less than 0.001). The thickness of the inner layer of carotid arteries was more marked in smoking cotwins (p less than 0.001). The size of plaques and the degree of inner layer thickening correlated with the dose of smoking (NS). 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.

Evidence that smoking alters prostacyclin formation and platelet aggregation in women who use oral contraceptives

Smoking markedly intensifies the risk of cardiovascular disease in women who use oral contraceptives. The mechanism of this effect is not known, but evidence in vitro and in male smokers suggests that nicotine and cigarette smoke can alter prostaglandin formation and platelet function. However, these effects had not been studied with regard to women. We evaluated the effects of smoking on prostacyclin formation and platelet aggregation in 38 women who were matched according to age and weight. These included 24 women who used oral contraceptives (15 smokers, 9 nonsmokers) and 7 smokers who did not use oral contraceptives. In addition, a control group comprised seven healthy, nonsmoking women who did not take oral contraceptives. Prostacyclin formation, reflected by the excretion rate of its stable metabolite 6-keto-prostaglandin F1 alpha, was measured by means of radioimmunoassay in 4-hour urine specimens obtained during a smoking-free period and after participants had inhaled smoke from four high-nicotine cigarettes. In addition, ex vivo platelet aggregation in response to adenosine diphosphate and the stable thromboxane/endoperoxide analog U 46619 was evaluated before and after the inhalation of cigarette smoke. Oral contraceptive users who smoked greater than or equal to 5 years had a lower basal 6-keto-prostaglandin F1 alpha level than nonsmokers or those with a smoking history of less than 5 years (84 +/- 11 versus 159 +/- 28 versus 171 +/- 18 ng/gm of creatinine, p less than 0.01). Inhalation of smoke from four high-nicotine cigarettes did not alter 6-keto-prostaglandin F1 alpha in the smokers who did not use oral contraceptives. However, excretion of 6-keto-prostaglandin F1 alpha was further reduced in the smokers who used oral contraceptives (133 +/- 20 to 86 +/- 9 ng/gm of creatinine, p less than 0.05). Platelet aggregation did not change after inhalation of cigarette smoke in the women who did not take oral contraceptives, but aggregation increased in participants who used oral contraceptives. These results suggest that prostacyclin inhibition may be an important mechanism for the increased cardiovascular risk in women smokers who take oral contraceptives.

Comparison of blood-flow velocity waveforms in different coronary artery bypass grafts. Sequential saphenous vein grafts and internal mammary artery grafts

Characteristics of blood-flow velocities were investigated at different sites in two types of coronary artery bypass grafts, sequential saphenous vein grafts (SSVG) and internal mammary artery grafts (IMAG). The latter appear to have the longest life span. The patency rate of the side-to-side anastomosis of the SSVG is better than that of the end-to-side anastomosis. The SSVG was anastomosed to the major diagonal branch by side-to-side anastomosis and to the left anterior descending coronary artery (LAD) by end-to-side anastomosis in 13 patients who had 75-100% and 75-90% stenoses in the LAD and major diagonal branch, respectively. IMAG anastomoses were performed to the LAD in 10 patients with 75-100% stenoses of the artery. The blood-flow velocities were measured by the 20-MHz, eighty-channel ultrasound pulsed Doppler method during surgery. In six patients in the SSVG group, we investigated the configuration of velocity profiles at the region just proximal to the side-to-side anastomosis and at the bridge portion between the side-to-side and end-to-side anastomosis. In the other seven patients, we measured the blood-flow velocity at several centimeters proximal to the side-to-side anastomosis and compared it with that in the IMAG. At the region just proximal to the side-to-side anastomosis, the velocity profile skewed toward the anastomosis side wall in all patients, and the flow velocity near the wall opposite to the side-to-side anastomosis was reversed in five of six patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive and atherogenic effects of cigarette smoking: a study of monozygotic twins discordant for smoking

The mechanism by which atherosclerotic disease is induced by cigarette smoking has not yet been identified unequivocally. Chronic cigarette smoking and the generation of vasoactive prostanoids and the size of carotid atherosclerotic plaques were studied in nine pairs of identical male twins discordant for smoking for over 20 years. The urinary excretion of 2,3-dinor-thromboxane B2 (thromboxane B2 metabolite) of the smoking twin was significantly higher (on average 1.8 times higher) in every pair and that of 2,3-dinor-6-keto-prostaglandin F1 alpha (prostacyclin metabolite) was significantly higher (on average 1.3 times higher) in eight of the nine pairs. The ratio of excretion of these metabolites was significantly higher, being 4.0 (95% confidence interval 2.7 to 5.4) among the smokers compared with 2.9 (2.1 to 3.8) among the non-smokers, thus favouring a mechanism of vasoconstriction. Excretion of the thromboxane B2 metabolite was related to the urinary concentrations of nicotine metabolites. Atherosclerotic plaques detected by ultrasonography in the carotid arteries were significantly larger among smokers but did not correlate with the urinary excretion of prostacyclin and thromboxane B2 metabolites or intensity of smoking. Smoking was concluded to induce activation of platelets by an effect mediated by nicotine. The increased prostacyclin production, on the other hand, suggested a compensatory mechanism for the general vasoconstrictive properties of cigarette smoking.