Antioxidant vitamins and enzymatic and synthetic oxygen-derived free radical scavengers in the prevention and treatment of cardiovascular disease

Oxygen-derived free radical formation can lead to cellular injury and death. Under normal situations, the human body has a free radical scavenger system (catalase, superoxide dismutase) that can detoxify free radicals. Antioxidant vitamins and enzymatic and synthetic oxygen-derived free radical scavengers have been used clinically to prevent the formation of oxidized LDL and to prevent reperfusion injury, which is often caused by free radicals. In this article, the pathogenesis of free radical production and cell injury are discussed, and therapeutic approaches for disease prevention are presented.

Increased vascular compliance/decreased cardiovascular risk: what the studies tell us

Increasing arterial stiffness and decreasing arterial compliance are now thought to occur at the beginning of the hypertension disease process. Decreased arterial compliance is associated with isolated systolic blood pressure elevations. Many clinical trials of isolated systolic hypertension provide indirect evidence that improving compliance lowers the risk of cardiovascular disease. The Systolic Hypertension in the Elderly Program showed that antihypertensive therapy in older patients with isolated systolic hypertension lowers systolic blood pressure and narrows pulse pressure without unduly lowering diastolic blood pressure. Treatment over 5 years significantly reduced the incidence of stroke, nonfatal myocardial infarction and coronary death, all cardiovascular events, and all-cause mortality. The Systolic Hypertension in Europe and Systolic Hypertension in China trials showed similar effects on pulse pressure and on clinical end points. The Heart Outcomes Prevention Evaluation was a primary prevention study of the effect of an angiotensin-converting enzyme (ACE) inhibitor in subjects who were not necessarily hypertensive but were at risk for cardiovascular events. With minimal lowering of blood pressure, ramipril therapy provided significant risk reduction in all major end points--overall mortality, stroke, myocardial infarction, and cardiovascular death. ACE inhibitors restore endothelial cell balance to improve arterial compliance, thus they can provide benefits beyond lowering blood pressure.

Drug therapy of heart failure caused by systolic dysfunction in the elderly

The presence of multiple medical illnesses often distinguishes elderly patients with heart failure and can make pharmacologic management of symptomatic heart failure challenging in this population. Physiologic changes that occur with normal aging may complicate clinical assessment. Limited data from large clinical trials of heart failure therapy are applicable to aged patients. Available data suggest that elderly patients should be treated with the same regimen as younger patients but that more careful attention should be paid to dosing, especially when initiating a new drug. History and physical examination techniques can be used to uncover evidence of congestion and inadequate perfusion and are critical adjuncts when making therapeutic decisions. The objectives of therapy for elderly patients with heart failure must be individualized within the larger context of patients' goals and stage of life.

Therapeutic angiogenesis: a new treatment modality for ischemic heart disease

Angiogenesis is the process of new blood vessel formation, and has potential clinical use in the management of ischemic heart disease. A considerable amount of ongoing research has recently focused on the process of angiogenesis, including the identification of various factors that can inhibit or stimulate this process. The picture that is emerging suggests that a complex set of interactions involving various cells and cellular products is the key to angiogenesis. In particular, endothelial cells and growth factors, such as vascular endothelial growth factor and fibroblast growth factor, appear to play integral roles in angiogenesis. Various preclinical studies involving animal models of ischemia explored the potential use of angiogenesis in ischemic disease. Based on encouraging results, a number of clinical trials involving angiogenesis have been initiated to determine whether the process of angiogenesis also offers therapeutic benefit in humans.

Adrenomedullin: a vasoactive and natriuretic peptide with therapeutic potential

Adrenomedullin is a potent endogenous vasodilating and natriuretic peptide that is similar in structure to calcitonin gene-related peptide (CGRP). The gene involved in the synthesis of adrenomedullin has been localized to a single locus on chromosome 11, with specific sites on the genome to regulate transcription. Adrenomedullin is normally found in human plasma and in other organs. It is thought that one of the clearance sites for this peptide is in the pulmonary circulation. Endothelial cells are assumed to be one of the major sources of plasma adrenomedullin. Adrenomedullin is an important factor in regulating local and systemic vascular tone, by its activity as an autocrine/paracrine and circulating hormone. Depending on the site of action, adrenomedullin seems to bind to a CGRP receptor and send signals by either cyclic adenosine monophosphate or nitric oxide. From the results of experiments in animals, it has become clear that adrenomedullin's effects are species-specific. However, what is commonly seen with adrenomedullin is peripheral vasodilatation, a positive inotropic action, increased cardiac output, and increased stroke volume. In addition, adrenomedullin has actions in the brain, lungs, and kidneys to regulate regional hemodynamics. With these activities defined, recent studies have suggested a potential therapeutic role for adrenomedullin.

Adverse dermatologic effects of cardiovascular drug therapy

Cardiovascular disease is common, affecting an increasing number of persons as the population ages. To combat this growing health problem, physicians use a multitude of medications in the treatment of their patients. Although pharmacologic therapy greatly enhances quality of life for a majority of patients, there is always the potential for an unfavorable reaction. For example, cardiovascular drugs can induce a vast array of adverse dermatologic responses. This article reviews the various cutaneous reaction patterns that can occur as a result of treatment with specific cardiovascular agents.

Serotonin and the heart

Serotonin is a naturally occurring vasoactive substance that has diverse cardiophysiological effects. These effects can be explained by the existence of serotonin receptor subtypes which mediate different biological actions. The vasoconstrictive actions of serotonin are mediated by 5-HT2 serotonergic receptors, and serotonin also amplifies the release and activities of other vasoconstrictors, such as angiotensin and norepinephrine. Abnormalities in the serotonergic system may play an important role in the pathophysiology of multiple cardiovascular disease states such as systemic hypertension, primary pulmonary hypertension and peripheral vascular disease. Selective 5-HT2 serotonergic receptor blockers have been developed which appear to be potent vasodilators with therapeutic potential in various cardiovascular disease states. The largest clinical experience has been collected with ketanserin, and other agents in this class are being investigated. Prolongation of the ECG QT interval with 5-HT2 serotonergic receptor blockers may pose a potential risk with these treatments in some patients.

Cardiomyocyte aging is gender-dependent: the local IGF-1-IGF-1R system

To determine whether insulin-like growth factor 1 (IGF-1) and its receptor (IGF-1R) are implicated in the aging process of the heart, and if their impact differs in the two genders, the expression of IGF-1, and extracellular alpha-subunit and transmembrane beta-subunit of IGF-1R was measured in left ventricular myocytes isolated from male and female Fischer 344 rats at 3, 8, 12, 16, and 26 months after birth. Additionally, the extent of myocardial damage in both sexes was evaluated in rats at 3 and 26 months by confocal microscopy. Finally, ventricular hemodynamics was assessed in the closed-chest preparation. From 3 to 26 months, aging was characterized by an 83%, 84% decrease and disappearance in the quantity of IGF-1, IGF-1Ralpha and IGF-1Rbeta in male myocytes. Corresponding changes in female myocytes were 40%, 28% and 43%. These molecular modifications at the myocyte level were coupled with tissue injury, consisting of multiple foci of replacement fibrosis across the left ventricular wall. However, myocardial fibrosis in females was 76% and 77% significantly less than in the young and old male heart, respectively. These multiple age-associated events were accompanied by cardiac decompensation in the senescent male rat, while modest indices of ventricular dysfunction were detected in old female rats. In conclusion, the enhanced IGF-1-IGF-1R system in female myocytes may condition the favorable outcome of age in this gender.

Pharmacologic approaches for the management of systemic hypertension in pregnancy

Hypertension in pregnancy includes a group of distinct disorders that require special consideration in both prevention and pharmacologic treatment. In recent years, there have been few advances regarding the pathophysiology and prevention of preeclampsia, or in recommendations for first-line drug therapy of the hypertensive complications of preeclampsia. Similarly, the recommendations for pharmacologic treatment of women with chronic hypertension antedating pregnancy have changed little, primarily because first-line medications have the advantage of having been the subjects of extensive research experience. Recent clinical trials have demonstrated the efficacy and safety of various second-line drugs for treating hypertensive disorders of pregnancy; whether these therapies can eventually replace the standard recommended medications will require more extensive long-term investigation.

Cardiovascular drug therapy in the elderly

Cardiovascular diseases of various etiologies are most prevalent in the elderly, and there are many pharmacologic issues that need to be considered when prescribing drug therapies to this population. Aging itself alters the absorption, distribution, metabolism, and excretion of many drugs. Certain drugs, such as digoxin, lidocaine, and warfarin, need to be used with great caution in older patients because of a greater potential for drug toxicity. Elderly patients often are prescribed multiple drugs for different conditions, making them susceptible to major drug-drug interactions. Recommendations are provided to help ensure safe prescribing practices of cardiac drugs in older patients.

Clopidogrel: a new antiplatelet drug

Clopidogrel is a new drug in the recently developed class of thienopyridine derivatives that inhibits platelet function by an inhibitory action exerted through the membrane adenosine diphosphate receptor. Clopidogrel is a prodrug that must be metabolized to an active metabolite in the liver. The basic chemistry, pharmacodynamics and pharmacokinetics of the drug are reviewed. Clinical trials with clopidogrel, including its use in patients with stents postangioplasty, adverse reactions, and potential advantages over other agents are summarized.

Cardiovascular drug therapy in patients with hepatic diseases and patients with congestive heart failure

Hepatic impairment can alter the pharmacokinetic profiles of cardiovascular drugs, which can lead to unwanted toxicity. In the presence of cirrhosis, portosystemic shunting occurs and cytochrome P450 activity is reduced. Impaired oxygen uptake caused by changes in the liver's sinusoids, as proposed by the oxygen limitation theory, may also explain the alteration of drug metabolism seen in cirrhosis. With congestive heart failure, sinusoidal congestion and hypoperfusion of the liver are seen. Similar to cirrhosis, the common pathway for hepatic damage in congestive heart failure seems to be liver hypoxia, which may explain the disease's effect on drug metabolism. Since routine hepatic function tests do not always relate to the liver's ability to eliminate drugs, existing guidelines for dosing cardiovascular drugs in patients with hepatic impairment are limited. This article provides guidance for dosing cardiovascular drugs in cirrhotic and heart failure patients based on available research data. Altered drug metabolism, especially in congestive heart failure, tends to be overlooked or not realized in clinical practice. Therefore, further research is needed in congestive heart failure to better elucidate safe prescribing patterns.

Major depression as a risk factor for cardiovascular disease: therapeutic implications

This review was conducted to analyze the literature regarding the association between psychological depression and cardiovascular disease (CVD). The literature was reviewed through Medline and Psychlit. Articles were located using search terms such as depression, CVD, coronary artery disease, and cardiac risk factor. The search included articles from 1980 through 1999. Both the cross-sectional and prospective data suggest that psychological depression is a risk factor for and an aggravating factor of preexisting CVD. Proposed pathophysiologic mechanisms and therapeutic implications are discussed.

Imidazoline receptor agonist drugs for treatment of systemic hypertension and congestive heart failure

The imidazoline receptors recently have been discovered to be involved in the central nervous system control of sympathetic outflow. A new class of centrally acting antihypertensive agents, the imidazoline receptor agonists (rilmenidine and moxonidine), have been developed to control blood pressure effectively without the adverse effects of sedation and mental depression that usually are associated with centrally acting antihypertensive agents. This new generation of centrally acting antihypertensive agents is highly selective for the imidazoline receptor but has a low affinity for alpha(2)-adrenergic receptors. The usefulness of these agents in the treatment of congestive heart failure has not been demonstrated.

Efficacy of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors for prevention of stroke

OBJECTIVE

To determine if 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are effective in preventing fatal and nonfatal strokes in patients at increased risk of coronary artery disease.

DESIGN

Meta-analysis of randomized controlled trials. Clinical trials were identified by a computerized search of MEDLINE (1983 to June 1996), by an assessment of the bibliographies of published studies, meta-analyses and reviews, and by contacting pharmaceutical companies that manufacture statins. Trials were included in the analysis if their patients were randomly allocated to a statin or placebo group, and reported data on stroke events. Thirteen of 28 clinical trials were selected for review. Data were extracted for details of study design, patient characteristics, interventions, duration of therapy, cholesterol measurements, and the number of fatal and nonfatal stroke events in each arm of therapy. Missing data on stroke events were obtained by contacting the investigators of the clinical trials.

MAIN RESULTS

Among 19,921 randomized patients, the rate of total stroke in the placebo group was 2.38% (90% nonfatal and 10% fatal). In contrast, patients who received statins had a 1.67% stroke rate. Using an exact stratified analysis, the pooled odds ratio (OR) for total stroke was 0.70 (95% confidence interval [CI] 0.57, 0.86; p =.0005). The pooled OR for nonfatal stroke was 0.64 (95% CI 0.51, 0.79; p =.00001), and the pooled OR for fatal stroke was 1.25 (95% CI 0.71, 2.24; p =.4973). In separate analyses, reductions in total and nonfatal stroke risk were found to be significant only for trials of secondary coronary disease prevention. Regression analysis showed no statistical association between the magnitude of cholesterol reduction and the relative risk for any stroke outcome.

CONCLUSIONS

The available evidence clearly shows that HMG-CoA reductase inhibitors reduce the morbidity associated with strokes in patients at increased risk of cardiac events. Data from 13 placebo-controlled trials suggest that on average one stroke is prevented for every 143 patients treated with statins over a 4-year period.

How to use calcium antagonists in hypertension: putting the JNC-VI guidelines into practice. Joint National Committee for the Prevention, Detection, Evaluation and Treatment of High Blood Pressure

The prevention and treatment of hypertension remain as major challenges for clinicians all over the world. The recently published Sixth Report of the Joint National Committee for the Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC-VI) uses evidence-based medicine in providing guidelines to aid clinicians in the prevention, detection and treatment of high blood pressure, including pharmacological approaches. Calcium antagonists are used widely for the treatment of hypertension, and JNC-VI focuses on specific situations where calcium antagonists could be considered as preferred treatments. There are a large number of calcium antagonists available, with a variety of pharmacodynamic and pharmacokinetic actions. Several sustained-release formulations of these drugs are also available. In terms of blood pressure control, calcium antagonists are more effective as antihypertensive treatments than beta-blockers, ACE inhibitors and angiotensin II receptor blockers in Black patients. The dihydropyridine calcium antagonists have been shown to reduce morbidity and mortality in elderly patients with isolated systolic hypertension. The rate-lowering calcium antagonists can be used as alternatives to beta-blockers in patients with coronary artery disease and hypertension. Calcium antagonists can be used as alternatives to ACE inhibitors in patients with hypertension and concomitant diabetes mellitus and/or renal disease. Some dihydropyridine calcium antagonists may be useful as alternatives to ACE inhibitors in patients with hypertension and systolic heart failure. Calcium antagonists appear to be extremely useful in patients with cyclosporin-induced hypertension, and in patients with hypertension and concomitant Raynaud's phenomenon and/or migraine. The rate-lowering agents can be used in patients with atrial tachyarrhythmias and hypertension. Clinicians should be aware of drug-drug interactions involving calcium antagonists, especially after the recent problems with mibefradil. Although retrospective studies have caused controversy regarding the safety of calcium antagonists in patients with hypertension, recent prospective studies have revealed no major safety concerns with these drugs.

Self-rated health assessment and development of both cardiovascular and dementing illnesses in an ambulatory elderly population: a report from the Bronx Longitudinal Aging Study

As part of the Bronx Longitudinal Aging Study, a prospective, community-based study designed to assess risk factors for cardiovascular and cerebrovascular morbidity and mortality and all-cause dementia, the investigators sought to determine whether a self-rated health assessment (SRHA) could be used as an independent predictor of new cardiovascular events and dementia (Alzheimer type and multi-infarct). A population of elderly (mean age 79 years) outpatient, ambulatory, nondemented patients (n = 487, 65% women) participated in this longitudinal study. Clinical diagnoses were made according to established criteria. At baseline, participants were asked to rate their current SRHA as excellent, good, fair, or poor, and were evaluated annually for as long as 10 years. Baseline SRHA findings were related to development of cardiovascular events and dementia. The SRHA was reported as excellent by 45 patients (9.4%), good by 212 (44.4%), fair by 178 (37.3%), and poor by 42 (8.8%). Using a multivariate analysis, patients whose SRHA was poor were 4.5 times more likely than those whose SRHA was excellent to have a fatal cardiovascular event, 2.6 times more likely to have a nonfatal cardiovascular event, and 5.3 times more likely to develop Alzheimer type and multi-infarct dementia. Similar findings were observed with dichotomous SRHA responses (comparing excellent/good to fair/poor). In an elderly population, SRHA appears to be an independent predictor of future cardiovascular and cerebrovascular events and development of all-cause dementia, which has possible therapeutic implications for prevention and treatment.