Effects of oral contraceptives on vascular endothelium in premenopausal women

OBJECTIVE

Premenopausal women are protected against atherosclerosis by high plasma estrogen levels, which have been suggested to augment endothelial nitric oxide synthesis and to improve endothelial function. In contrast, premenopausal use of oral contraceptives is associated with an increased cardiovascular risk. We investigated the influence of oral contraception on endothelial function.

STUDY DESIGN

Sixteen healthy premenopausal women with a mean age (+/-SD) of 27 +/- 3 years, 8 of whom used oral contraceptives and 8 of whom did not, were examined in a case-control study. Forearm plethysmography was used to measure changes of forearm blood flow in response to intra-arterial infusion of increasing doses of acetylcholine, sodium nitroprusside, and N (G)-monomethyl-L -arginine.

RESULTS

Endothelium-dependent vasodilatation (change from baseline after acetylcholine 48 microg/min) was similar between women with (828% +/- 137%) and without oral contraception (701% +/- 114%; P not significant), as was endothelium-independent vasodilatation (change from baseline after sodium nitroprusside 3200 ng/min, 271% +/- 38% vs 289% +/- 23%; P not significant). In contrast, inhibition of nitric oxide synthase with N (G)-monomethyl-L -arginine induced a significantly more marked decrease in blood flow among women with oral contraception than among those without at all dosages (change from baseline after 4-micromol/min N (G)-monomethyl-L -arginine, -26% +/- 3% vs -14% +/- 5%; P =.009 by analysis of variance).

CONCLUSION

Stimulated nitric oxide bioavailability remained unaffected in a group of premenopausal women receiving oral contraceptives. In contrast, basal nitric oxide production and release appeared to be enhanced by oral contraceptive use.

Cardiovascular and mood responses to quantified doses of cigarette smoke in oral contraceptive users and nonusers

Previous research suggests that the female sex hormones may moderate cardiovascular and mood responses to cigarette smoking and abstinence. To test this possibility, acute effects of cigarette smoking on cardiovascular reactivity and mood were examined in 12 oral contraceptive users and 12 nonusers across two menstrual phases (early and late cycle). After overnight deprivation, each participant attended two sessions in which they first sham-smoked and then smoked two standard cigarettes, via a quantified smoke delivery system. Oral contraceptive users exhibited larger cigarette smoking-induced increases in heart rate compared with nonusers. In addition, cigarette smoking-induced cardiovascular changes varied with both the phase of the menstrual cycle and oral contraceptive use. No menstrual phase-dependent effects were observed for tobacco withdrawal symptoms, premenstrual symptoms, or moods prior to smoking. Cardiovascular hyperreactivity to cigarette smoke in oral contraceptive users may help explain the mechanisms by which smoking and oral contraceptive use contribute to an elevated risk for coronary heart disease.

Oral contraceptive use and hemodynamic, lipid, and fibrinogen responses to smoking and stress in women

The effects of acute smoking and oral contraceptive (OC) use on cardiovascular, lipid, and fibrinogen stress responses were examined in 52 female smokers and nonsmokers, half of whom were using OCs. Women smoked or sham-smoked a cigarette and then performed 2 stressful tasks. Stress elicited increases in total and low-density lipoprotein cholesterol, and in triglycerides among women who smoked, and in fibrinogen among all women. Smokers who used OCs had greater blood pressure increases to smoking and to stress than did smokers who did not use OCs. OC use was also associated with enhanced total peripheral resistance stress responses among women who smoked and cardiac output stress responses among women who sham-smoked. Results suggest that OC use moderates cardiovascular reactivity in smokers but not nonsmokers, enhancing vascular responsivity to smoking combined with stress and myocardial responsivity to stress alone.

Cardiovascular disease: pathogenesis, epidemiology, and risk among users of oral contraceptives who smoke

Smoking increases the risk of lung cancer and cardiovascular disease among persons of both sexes. The risk of cardiovascular disease is further increased among users of oral contraceptives who smoke, particularly those who are >/=35 years old or carry the coagulation factor V Leiden mutation. Other important cardiovascular disease risk factors in women include waist/hip girth ratio >0.8, high concentration of low-density lipoprotein cholesterol (>115 mg/dL), high triglyceride level (>/=150 mg/dL) with low concentration of high-density lipoprotein cholesterol (</=45 mg/dL), high ratio of total cholesterol/high-density lipoprotein (4.0), high ratio of low-density lipoprotein/high-density lipoprotein (3.0), glucose values >/=100 mg/dL, hypertension, lack of physical activity, and high-fat diet. Most excess cardiovascular disease among users of oral contraceptives is due to thrombosis (not atherosclerosis); studies indicate that the lower the oral contraceptive estrogen dose is, the lower is this risk. Oral contraceptives containing the third-generation progestins desogestrel and gestodene have been associated with greater risks of venous thromboembolism than are associated with older progestins, although there is some controversy surrounding these findings.

Effects of smoking on prostacyclin formation and platelet aggregation in users of oral contraceptives

OBJECTIVE

The aim of this review was to determine which subgroups within the population of smokers and oral contraceptive users are at especially elevated risk for thromboembolic events.

STUDY DESIGN

This review covers 10 articles published between 1981 and 1996 that examined the effects of smoking and oral contraceptive use, in conjunction or independently, on factors affecting the coagulation pathway, particularly the expressions of prostacyclin and thromboxane.

RESULTS

Heavy, prolonged, or current nicotine use was associated with a reduction in the urinary metabolite of prostacyclin (prostaglandin I2) in oral contraceptive users. Smoking and increased excretion of thromboxane were also linked, and in 1 study the effect was dose related. These changes were associated with increased platelet aggregation. Oral contraceptive use and concurrent smoking increased the risk of acute myocardial infarction by a ratio of 10.1. Although most of this risk was seen among smokers who used second-generation oral contraceptives (odds ratio 11.1), with a much reduced odds ratio for smokers who used third-generation oral contraceptives (odds ratio 3.1), the study was not controlled for estrogen dose. A reduction in myocardial infarction risk compared with that in the 1970s was seen for all oral contraceptive users, probably because of the reduced hormonal doses in current preparations.

CONCLUSION

Smoking, not oral contraceptive use, constitutes the greater cardiovascular risk. However, cigarette smoking and oral contraceptive use act synergistically to increase the risk of thromboembolic events. Differences in oral contraceptive formulations may mitigate the increased risk resulting from concurrent smoking and use of oral contraceptives, but whether the progestin component or the lowered estrogen dose is responsible is unclear.

Oral contraceptive use and hemodynamic, lipid, and fibrinogen responses to smoking and stress in women

The effects of acute smoking and oral contraceptive (OC) use on cardiovascular, lipid, and fibrinogen stress responses were examined in 52 female smokers and nonsmokers, half of whom were using OCs. Women smoked or sham-smoked a cigarette and then performed 2 stressful tasks. Stress elicited increases in total and low-density lipoprotein cholesterol, and in triglycerides among women who smoked, and in fibrinogen among all women. Smokers who used OCs had greater blood pressure increases to smoking and to stress than did smokers who did not use OCs. OC use was also associated with enhanced total peripheral resistance stress responses among women who smoked and cardiac output stress responses among women who sham-smoked. Results suggest that OC use moderates cardiovascular reactivity in smokers but not nonsmokers, enhancing vascular responsivity to smoking combined with stress and myocardial responsivity to stress alone.

Estimates of the risk of cardiovascular death attributable to low-dose oral contraceptives in the United States

OBJECTIVE

Our purpose was to estimate the annual risk of death in the United States from cardiovascular disease attributable to low-dose combination oral contraceptives.

STUDY DESIGN

Estimates of the risk of death from cardiovascular disease attributable to low-dose oral contraceptives were modeled on data from studies published through 1997 and from age-specific mortality rates in the United States for 1993 and 1994.

RESULTS

Attributable risk of death from cardiovascular disease resulting from oral contraceptive use is 0.06 and 3.0 per 100,000 nonsmokers 15 to 34 years of age and 35 to 44 years of age, respectively. In smokers this risk increases, respectively, to 1.73 and 19.4 per 100,000 users in these 2 age groups; however, 97% and 85% of this risk is due to the combined effects of smoking and using oral contraceptives. The attributable risk of death from cardiovascular disease in nonsmoking oral contraceptive users is lower than the risk of death from pregnancy in nonusers of oral contraceptives at all ages; however, among smoking oral contraceptive users more than 35 years of age, the excess risk of death from oral contraceptives is higher than the risk of death from pregnancy.

CONCLUSION

There is virtually no excess attributable risk of death from cardiovascular disease related to oral contraceptive use in young women. However, smokers more than 35 years of age should use a nonestrogen contraceptive.

[Contraception after heart transplantation]

It was observed that fertility and menstrual function in heart-transplanted women, impaired before the operation, become normal with a new heart. The restoration of reproductive function is also confirmed by many cases of pregnancy in heart-transplant recipients, reported in the literature. Twenty-four cases were published worldwide up to 1997, out of which eighteen had a positive result. Also a case personally treated was successful. The outcome of a pregnancy after heart transplantation is, then, generally positive. Nevertheless, such a pregnancy involves important maternal and fetal risks. Thus, the gynecologist has to provide correct information about both such risks and the most suitable contraceptive methods, for these patients. Oral contraceptives are very effective and, in the new low-dose formulations, free from serious adverse effects. No adverse effects have been observed in our patient, who represents the only case, reported in the literature, in which an estroprogestinic contraception was utilized before a pregnancy. In conclusion, during an oral contraception or after a tubal sterilization, pregnancy is really unlikely to occur. Thus, when the couple either has completed the familial nucleus or does not desire offspring, a doubt is at least justified as to whether these safer methods of contraception are advisable in such women.

[Contraceptive use in women with heart disease]

PURPOSE

To analyse efficacy, tolerance and adverse events of reversible contraceptives in women with cardiac disease.

METHODS

We studied prospectively during 24-39 (mean = 29) months, 89 women with heart disease with a mean age of 25.6 (16-42) years. Rheumatic heart disease was present in 73 (82%) cases, congenital heart disease in 11 (11%), coronary artery disease in 2 (2%) and cardiomyopathy in 3 (3%) case. The patients were divided in three groups: GCO--35 patients taking combined oral contraceptives (30 micrograms ethinyl estradiol and 75 micrograms gestodene--COs); GIT--27 using injectable progestagens (depot medroxyprogesterone acetate-DMPA) and GUID--27 with intrauterine device (IUD).

RESULTS

In GCO occurred 4 (11.4%) cases of arterial hypertension, 1 (2.8%) of a transient cerebral isquemic attack, 3 (8.5%) of spotting, 1 (2.8%) of amnorrhea e 1 (2.8%) pregnancy. Interruption of this method occurred in 4 (11.4%) cases due to hypertension (2), pregnancy (1) and amenorrhea (1). In group GIT there were 2 (7.4%) cases of arterial hypertension, 18 (66.6%) of amenorrhea, and 3 (11.1%) of spotting. Interruption of use occurred in 5 (18.5%) due to amnorrhea (2), weight gain (2) and headache (1). In GUID there was 1 (3.7%) case of infeccion, 1 (3.7%) pregnancy and 1 (3.7%) spontaneous expulsion of IUD. Interruption of use took place in 3 (11.1%) cases due to infeccion, pregnancy and expulsion. The comparation between the groups demonstrated a difference in the incidence of amenorrhea (p < 0.005) and descontinuation of use of the method (p < 0.025).

CONCLUSION

Use of reversible contraceptives in heart disease women was associated with an acceptable cardiovascular risk. Efficacy and side effects of the methods were comparable in the groups, however intolerance was more observed in GIT.

Contraception and dyslipidemia

The risks of cardiovascular disease associated with dyslipidemia differ in women and men, being more strongly associated with triglyceride/high-density lipoprotein in middle-aged women than in men. Although the incidence of heart disease is lower in women because they live longer, over a lifetime, cardiovascular disease in women is equal to that in men, with the greatest incidence after age 65 years. Major coronary events are rare among reproductive-age women who use oral contraceptives and are related to the concomitant effects of age, smoking, diabetes, hypertension, and obesity. Low estrogen-progestin dose oral contraceptives appear not to promote cardiovascular disease and can be used in women with controlled cholesterol elevations. Alternative contraceptive measures should be considered for patients with severe uncontrolled hypercholesterolemia or a lipid disorder that carries a high risk of coronary heart disease. In these conditions, thrombotic propensity associated with supraphysiologic doses of estrogen in oral contraceptives might accelerate coronary thrombosis should an arteriosclerotic plaque rupture. Treatment of hypercholesterolemia should follow the guidelines of the National Cholesterol Education Program and emphasize hygienic measures. Contraceptive selection in hyperlipidemic patients should reflect a balance between the risks--and their management--of developing cardiovascular disease versus the risks of pregnancy.

Cardiovascular disease in women and noncontraceptive use of hormones: a feminist analysis

Cardiovascular disease (CVD) in women is being defined by biomedical researchers and physicians as part of the menopausal syndrome. Postmenopausal lowered levels of estrogen are presented as a prime cause of changes in cholesterol levels that are a risk factor for CVD. The biomedical model and hormone debate are described and analyzed, followed by a feminist perspective of CVD. This includes new federal policies that support CVD research. Nurses are encouraged to present a broader picture of CVD and its risks than that presented by the biomedical model and to empower women's understanding of this complex health issue through educational, clinical, and research endeavors.

Lipids and cardiovascular disease: do the findings and therapy apply equally to men and women?

Dyslipoproteinemia is prevalent in women as well as in men. In both, its consequences--premature atherosclerosis and CAD morbidity and mortality--are more common. Although clinical evidence of the benefits of cholesterol lowering is less abundant in women, it is not entirely absent. As in men, cholesterol lowering in women is associated with a decline in CAD risk and with regression of coronary atherosclerosis. Lipoprotein risk factors have some special characteristics in women. Low-density lipoprotein cholesterol may be a less important risk factor in women, perhaps because estrogen protects the arterial wall against LDL deposition. High-density lipoprotein cholesterol is a better predictor of risk in women than in men. Triglycerides are an independent predictor of CAD risk in postmenopausal women. The effects of endogenous gonadal hormones in life-cycle changes in women is evident. As girls pass through puberty, HDL-C levels do not fall as they do in boys of the same age. In pregnancy, LDL-C, HDL-C, and triglyceride levels all rise. However, LDL-C stays elevated until well after delivery, whereas triglycerides fall to baseline at about the time of delivery, and HDL-C levels begin to fall at about 24 weeks. Interestingly, this fall in HDL-C is not accompanied by a fall in apoA-I levels, implying a change in HDL composition during the latter portion of pregnancy. After menopause, LDL-C levels rise sharply, whereas HDL-C levels decline modestly. Again, this decline in HDL-C is accompanied by a rise in apoA-I levels, implying a change in HDL composition. Diet, weight loss, and exercise are less effective in altering lipoprotein levels in women than in men. The reasons for this are not clear, although it is reasonable to speculate that endogenous gonadal hormones play a role. Genetic dyslipoproteinemia occurs in women, although the effect on CAD rates may be mitigated by the generally higher levels of HDL-C enjoyed by women. Exogenous hormones in the form of OCs and postmenopausal HRT affect circulating lipoprotein levels according to their composition. Generally, estrogens have favorable effects, raising HDL-C and lowering LDL-C levels. Progestins are either neutral or oppose estrogen effects, depending on their dose and androgenicity. Use of modern OCs probably does not adversely affect CAD risk except in combination with cigarette smoking. However, HRT has a strong favorable effect on CAD risk when unopposed estrogen is used, probably due to increases in HDL-C levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Oral contraceptives and coronary heart disease

In industrialized countries, coronary heart disease (CHD) is a major public health problem for both men and women. Preventive strategies for reducing the excessive mortality and morbidity associated with CHD involve the identification and modification of metabolic factors believed to be involved in the disease process. Three major areas of concern are lipid metabolism, carbohydrate metabolism and the hemostatic system. The steroid hormones contained in oral contraceptives (OCs) have been shown to interfere in all three areas. In many instances OCs have been shown to alter metabolic markers for CHD in directions associated with increased risk. Although evidence is lacking that such changes induce CHD in users of modern, low-dose OCs, it would be prudent to develop formulations with a minimal impact on metabolic risk markers. There is increasing evidence that many of the metabolic disturbances seen in CHD patients share a common origin, and the development of risk-free OCs is likely to require investigation into complex interrelationships.

Women, lipoproteins and cardiovascular disease risk

Atherosclerosis, lipoprotein structure, lipoprotein metabolism and role in atherogenesis, epidemiology of lipoproteins and coronary artery disease, and current public health guidelines for cholesterol control are described. Low density lipoprotein cholesterol levels rise with age in both men and women. High density lipoprotein (HDL) levels decline after menopause. Special aspects of coronary risk in women include the stronger role of diabetes, hypertriglyceridemia and HDL. In addition, the effects of exogenous hormone therapy, both in the form or oral contraceptives and post menopausal hormone replacement should be considered. Careful attention to these issues may reduce cardiovascular morbidity in adult women.

Lipids, clotting factors, and diabetes: endogenous risk factors for cardiovascular disease

Theories of intimal injury leading to plaque formation include platelet adhesion and production of growth factors, hypercholesterolemia, smooth muscle cell proliferation, macrophage activity, defective utilization of low-density lipoproteins via deficient receptors, and deficiency in cellular lysosomal enzymes. High levels of low-density lipoproteins and intermediate-density lipoproteins, as well as their apoproteins, are strong risk factors for cardiovascular disease. The lowering of the cholesterol level has been shown to produce significant regression of atherosclerotic lesions. Data also suggest an interaction between lipids and platelets, although the role of coagulation disorders as an independent risk factor for atherosclerosis is difficult to assess. Although much of the data are controversial, there is evidence that platelet survival time is a strong predictor of severe vessel damage. In addition, some studies have reported decreased activity of antithrombin III with coronary artery disease, and there appears to be a direct correlation between fibrinogen and cholesterol levels. Finally, diabetes mellitus (both types I and II) is a significant independent risk factor for atherosclerosis. The risk is not related to the severity or duration of diabetes, and it appears to be greater in women than in men.

Relative and absolute excess risks of coronary heart disease among women who smoke cigarettes

We prospectively examined the incidence of coronary heart disease in relation to cigarette smoking in a cohort of 119,404 female nurses who were 30 to 55 years of age in 1976 and were free of diagnosed coronary disease. During six years of follow-up, 65 of the women died of fatal coronary heart disease and 242 had a nonfatal myocardial infarction. The number of cigarettes smoked per day was positively associated with the risk of fatal coronary heart disease (relative risk = 5.5 for greater than or equal to 25 cigarettes per day), nonfatal myocardial infarction (relative risk = 5.8), and angina pectoris (relative risk = 2.6). Even smoking 1 to 4 or 5 to 14 cigarettes per day was associated with a twofold to three-fold increase in the risk of fatal coronary heart disease or nonfatal infarction. Overall, cigarette smoking accounted for approximately half these events. The attributable (absolute excess) risk of coronary heart disease due to current smoking was highest among women who were already at increased risk because of older age, a parental history of myocardial infarction, a higher relative weight, hypertension, hypercholesterolemia, or diabetes. In contrast, former smokers had little, if any, increase in risk. These prospective data emphasize the importance of cigarette smoking as a determinant of coronary heart disease in women, as well as the markedly increased hazards associated with this habit in combination with other risk factors for this disease.