Acute saline infusion reduces alveolar-capillary membrane conductance and increases airflow obstruction in patients with left ventricular dysfunction

BACKGROUND

Impaired alveolar-capillary membrane conductance is the major cause for the reduction in pulmonary diffusing capacity for carbon monoxide (DLCO) in heart failure. Whether this reduction is fixed, reflecting pulmonary microvascular damage, or is variable is unknown. The aim of this study was to assess whether DLCO and its subdivisions, alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (Vc), were sensitive to changes in intravascular volume. In addition, we examined the effects of volume loading on airflow rates.

METHODS AND RESULTS

Ten patients with left ventricular dysfunction (LVD) and 8 healthy volunteers were studied. DM and Vc were determined by the Roughton and Forster method. The forced expiratory volume in 1 second (FEV1), vital capacity, and peak expiratory flow rates (PEFR) were also recorded. In patients with LVD, infusion of 10 mL. kg-1 body wt of 0.9% saline acutely reduced DM (12.0+/-3.3 versus 10.4+/-3.5 mmol. min-1. kPa-1, P<0.005), FEV1 (2.3+/-0.4 versus 2.1+/-0.4 L, P<0.0005), and PEFR (446+/-55 versus 414+/-56 L. min-1, P<0.005). All pulmonary function tests had returned to baseline values 24 hours later. In normal subjects, saline infusion had no measurable effect on lung function.

CONCLUSIONS

Acute intravascular volume expansion impairs alveolar-capillary membrane function and increases airflow obstruction in patients with LVD but not in normal subjects. Thus, the abnormalities of pulmonary diffusion in heart failure, which were believed to be fixed, also have a variable component that could be amenable to therapeutic intervention.

Baseline clinical characteristics of patients recruited into the assessment of treatment with lisinopril and survival study

BACKGROUND

The beneficial effect of ACE inhibitors on mortality has been established in a series of trials. However, in clinical practice, ACE inhibitors are commonly administered in doses much lower than those shown to be effective in the landmark trials.

AIMS

This report describes the baseline characteristics of the patients recruited into the ATLAS study by age and gender sub-groups.

METHODS

The ATLAS study compared the effects of 'low' dose (2.5-5.0 mg/day) to 'high' dose (32.5-35.0 mg/day) lisinopril in a double-blind study of 3164 patients with moderate to severe heart failure and left ventricular ejection fraction < 30% during a mean follow-up period of 46 months. The primary end-point was all cause mortality and the principal secondary end-point a composite of all-cause hospitalisation or all-cause mortality.

RESULTS

Among patients with heart failure selected for the presence of left ventricular systolic function there were few differences among age groups or between genders. Older patients were not so heavy, were more likely to have ischaemic heart disease, hypertension and atrial fibrillation contributing to their heart failure and had a higher blood urea. Women were not so heavy as men. Age and gender had no major influence on mean ejection fraction or baseline treatment in the ATLAS study.

CONCLUSIONS

Weight and renal function may alter the plasma concentration of any given dose of an ACE inhibitor. Potential interactions between dose of lisinopril, weight and renal function will be explored after the study is completed.

Update of recent clinical trials in heart failure and myocardial infarction

BACKGROUND

There are currently many on-going clinical trials assessing therapies for the treatment of patients with heart failure.

AIMS

The purpose of this series of papers is to present concise summaries of current randomised trials in the field of heart failure and myocardial infarction (MI).

METHODS

Data from large double-blind, placebo-controlled trials, which are on-going or have only recently been published, are given in a format allowing easy comparison. Where appropriate, data from smaller studies are included.

RESULTS

Major studies which are examined in this issue include CIBIS II, MERIT-HF, RESOLVD, SPICE, VEST, MACH-1, ATLAS, RALES, CIDS and CASH. These trials assess the efficacy and safety of beta-blocker, angiotensin-II-receptor blocker, positive inotropic agent, calcium antagonist, angiotensin-converting enzyme (ACE) inhibitor, aldosterone receptor blocker, and antiarrhythmic interventions in the treatment of heart failure.

CONCLUSIONS

The presentation of data from these on-going trials should allow an up-to-date assessment, by physicians, of the most appropriate and effective treatment for patients with heart failure. It is evident that some therapies may play no further role in the treatment of heart failure, due to the increased risk of mortality associated with their administration, whilst others may convey significant benefits.

Post-partum sexual abstinence in West Africa: implications for AIDS-control and family planning programmes

OBJECTIVE

To assess whether the custom of prolonged post-partum sexual abstinence in Benin is associated with an increased incidence of extra-marital sexual contacts by husbands.

DESIGN

Cross-sectional survey of adult men and women.

METHODS

Data obtained from men on their extra-marital sexual behaviour in the past 12 months were linked to data on post-partum abstinence over the same time interval reported by wives. Multivariate analysis was applied to assess the association between conjugal abstinence and husband's extra-marital sex, net of the effects of possible confounders.

RESULTS

Approximately half of married men experienced post-partum abstinence in the past 12 months. In this group, 32% reported one or more extra-marital sexual contacts compared with 20% among those who experienced no abstinence (OR = 1.8, P < 0.001). This association is essentially unchanged after controlling for marriage type, age, education, urban-rural residence, income and household wealth. Age, income and wealth are also significant predictors of the probability of extra-marital sex. The effects of income and wealth largely disappear when attention is restricted to extra-marital sex without using a condom on the most recent occasion.

CONCLUSIONS

The potentially protective effect of prolonged abstinence after childbirth in Benin (and probably in much of West Africa) is offset by an increased probability that husbands will seek extra-marital partners without using condoms. Although not quantifiable, the enhanced longer-term risks of sexually transmitted diseases/HIV infection for wives probably outweigh the short-term benefits. Family planning practitioners in this region should not hesitate to recommended the early resumption of sex and suitable methods of post-partum contraception for women who express concern or uncertainty about their husband's behaviour.

Health economic consequences of the pharmacological treatment of heart failure

Health economics is about spending limited resources wisely and, as with so many fields in medicine, combines science with art and ingenuity. In order to know whether money is well spent it is necessary to have some reference points to make comparisons. Many accepted cardiovascular interventions, such as revascularization for multivessel disease (US$50000 per life year gained) or the use of a statin for hypercholesterolaemia in middle-aged men at high risk of cardiovascular events (US$30000 per life year gained) are associated with moderate expense. By contrast heart failure is one of the few conditions in which, under some circumstances, lives may be saved while significantly reducing costs. This article seeks to review currently available reports on the health economic consequences of interventions for heart failure and describes the development of a new health economic model. Digoxin, ACE inhibitors and beta-blockers all appear to be cost-effective under widely differing sets of assumptions. Estimates range from a substantial cost-saving to a few thousand dollars per life year gained. The major factor limiting the reduction in costs associated with effective treatment for heart failure (with the exception of digoxin) is the costs incurred as a consequence of improved longevity. Money spent on treating heart failure well is money wisely spent.

Etiology and response to drug treatment in heart failure

Clinical trials in heart failure (HF) tend to randomize patients according to demographic characteristics and severity of left ventricular dysfunction, without taking account of the precise diagnosis. This article reviews results from recent trials suggesting that the etiology of HF, and particularly whether it is ischemic or nonischemic, may influence the long-term prognosis and the response to treatment. Some studies, but not all, suggest that nonischemic HF has a better prognosis than ischemic HF. The data on the benefits of angiotensin-converting enzyme inhibitors in ischemic versus nonischemic HF are conflicting. Carvedilol, and recently, bisoprolol have been shown to reduce mortality in ischemic and nonischemic HF, whereas metoprolol has, to date, improved prognosis only in dilated cardiomyopathy. Better responses to digoxin, amlodipine and amiodarone have been reported in non-ischemic HF. There is at present no clear explanation for the apparent therapeutic differences between ischemic and nonischemic HF. Absence of a rigorous definition of "nonischemic HF" in many studies makes interpretation of the results difficult. Further studies to clarify the effects of etiology of HF on the response to treatment could be particularly important for preventing progression to more advanced stages, in which any type of drug therapy may have limited value in prolonging survival. An individualized therapeutic approach, based on etiology of HF and possibly other factors such as plasma drug levels or the levels of neurohormones, could result in major progress in treating HF patients.

Therapeutic options and cost considerations in the treatment of ischemic heart disease

Ischemic heart disease is a serious health problem because it causes considerable mortality and morbidity. Given the limited resources for health care, it is important to establish the costs associated with the benefits of its various treatment options. We therefore assessed the costs and benefits of medical treatment versus revascularization in a hypothetical cohort of 100 patients. A spreadsheet model was constructed using published data. The main outputs of this model were health-service costs per year and quality-adjusted survival estimates. In the United Kingdom, costs for treatments of less than 5,000 Pounds/quality-adjusted life-year (QALY) are perceived as highly cost effective, whereas those over 10,000 Pounds/QALY are considered expensive. For patients with intractable symptoms, surgery is highly effective and has benefits on prognosis. In patients with well-controlled symptoms on medical therapy, the benefits of surgery are small and uncertain, and therefore medical therapy is the most cost-effective treatment. Overall, the preferred cost-effective option favored medical treatment.

Beta-blockers for chronic heart failure: from prejudice to enlightenment

Experience accumulated from several large trials strongly suggest that beta-blockers should be used for the management of congestive heart failure (CHF). Beta-blockade should be added to conventional therapy such as diuretics, ACE inhibitors, and digoxin, as this was the approach used in the major trials. It is appropriate to treat patients with mild, moderate and, when stable, severe CHF. The benefits obtained include improvements in left ventricular function, reductions in symptoms and morbidity, improvement of quality of life, and delay of clinical progression, reflected by a reduced need for hospitalization and a reduction in mortality. Beta-blockers are much better tolerated, when used appropriately in selected patients, than was previously supposed.

Endothelin-1 has haemodynamic effects at pathophysiological concentrations in patients with left ventricular dysfunction

OBJECTIVES

Plasma levels of immunoreactive endothelin-1 (ET-1) are raised in chronic heart failure. Whether plasma ET-1 contributes to the haemodynamic derangement found in chronic heart failure is not known. We investigated the effects of exogenous ET-1 on the pulmonary and systemic vasculature in patients with left ventricular systolic dysfunction (LVD), with or without overt heart failure.

METHODS

ET-1 was infused at 1, 5 and 15 pmol/min into a distal pulmonary artery of ten patients with LVD to achieve plasma concentrations of ET-1 similar to those found in patients with heart failure and pulmonary hypertension. Haemodynamics were measured using a pulmonary thermodilution catheter and an arterial line. Intravascular Doppler and local pulmonary angiography were used to assess local pulmonary blood flow in the first four patients.

RESULTS

Systemic haemodynamic changes occurred with ET-1 infusion: mean arterial pressure (100 +/- 3 [standard error of the mean]) to 107 +/- 3 mmHg; p < 0.01) and systemic vascular resistance (1699 +/- 118 to 2033 +/- 135 dynes s/cm5; p < 0.001) rose, while the cardiac index fell from 2.43 +/- 0.17 to 2.20 +/- 0.16 l/min/m2 (p < 0.002). Mean pulmonary artery pressure (21 +/- 2 mmHg) and pulmonary vascular resistance (151 +/- 14 to 147 +/- 14 dynes s/cm5) did not change however.

CONCLUSIONS

Exogenous ET-1, when infused to achieve plasma concentrations similar to those in severe heart failure and pulmonary hypertension, causes systemic but not pulmonary vasoconstriction.

Are symptoms the most important target for therapy in chronic heart failure?

Symptoms combined with a loss of quality of life can be considered part of the morbidity of heart failure. Patients with chronic heart failure (CHF) have a poorer quality of life than do those with other chronic conditions including arthritis and lung disease. Although there is no evidence to show a mortality benefit, diuretics are frequently used for symptomatic relief in CHF patients. Angiotensin converting enzyme (ACE) inhibitors have been shown both to improve symptoms and to reduce mortality; however, ACE inhibitors have yet to show any conclusive benefit in improving quality of life. Digoxin is widely used and offers symptomatic relief, but it has been shown to have no overall effect on mortality. More recently, certain beta-blockers have been shown to impact both morbidity and mortality in patients already receiving standard therapy including an ACE inhibitor and diuretics. This article reviews these and additional therapies currently used in the management of CHF in the context of their impact on the joint goals of reducing both morbidity and mortality.

Influence of concomitant disease on patterns of hospitalization in patients with heart failure discharged from Scottish hospitals in 1995

AIMS

To determine the prevalence of common, serious, concomitant conditions complicating admissions with heart failure and how such conditions influence the length of hospital stay.

METHODS AND RESULTS

Data from Scottish morbidity records (SMR1) were used to determine the rate of deaths and discharges for heart failure (ICD-9 428.0, 428.9), concomitant discharge diagnoses and length of stay in 1995. 27,477 SMR1 records listing heart failure as a diagnosis were identified with heart failure in the first position in 11,560 (42%) records. 63.3% of deaths or discharges results from emergency admission. 13.2% of admissions were associated with acute myocardial infarction, 7.3% with angina or chest pain, 11.8% with chronic airways obstruction, 8.3% with chronic or acute renal failure and 5.3% had had a stroke. Length of stay including those patients who died was 7.6 days when acute myocardial infarction was the principal diagnosis but 26.3 days when stroke was the principal diagnosis.

CONCLUSION

A large proportion of deaths and discharges for heart failure are associated with conditions other than heart failure that may precipitate, contribute to or complicate admission. Treatment for heart failure that does not also seek to reduce the risk associated with common concomitant diseases may miss opportunities to reduce the overall risk of hospitalization.

Should we screen for asymptomatic left ventricular dysfunction to prevent heart failure?

A programme to detect and treat asymptomatic left ventricular dysfunction would seem to fulfil all five principles of screening. Indeed, such a programme would appear to be at least as firmly based as those already in existence for, for example, cervical and breast cancer. Further evaluation of the screening of high risk groups to detect asymptomatic left ventricular systolic dysfunction with the aim of giving treatment to prevent the development of heart failure is merited.

Pulmonary and systemic responses to exogenous endothelin-1 in patients with left ventricular dysfunction

Plasma levels of immunoreactive endothelin-1 (ET-1) are elevated in chronic heart failure (CHF) and have been reported to correlate closely with pulmonary hemodynamic measurements. We investigated the effects of exogenous ET-1 on the pulmonary vasculature in patients with left ventricular systolic dysfunction (LVD), with or without overt heart failure. ET-1 was infused at 1, 5, and 15 pmol/min into a distal pulmonary artery of 10 patients with LVD. Hemodynamics were measured by a thermodilution catheter and arterial line. Intravascular Doppler and local pulmonary angiography were used to assess local pulmonary blood flow in the first four patients. Systemic hemodynamic changes occurred with ET-1 infusion in a dose-dependent fashion. Mean arterial pressure (100 +/- 8-107 +/- 11 mm Hg; p < 0.01) and systemic vascular resistance (1,699 +/- 375-2,033 +/- 427 dynes/s/cm-5; p < 0.001) rose, whereas the cardiac index fell from 2.43 +/- 0.53 to 2.20 +/- 0.491/min/m2 (p < 0.002). However, mean pulmonary artery pressure (21 +/- 7 mm Hg) and pulmonary vascular resistance (151 +/- 43-147 +/- 43 dynes/s/cm-5) did not change. Exogenous ET-1, when infused into patients with LVD, causes systemic but not pulmonary vasoconstriction.

Management strategies for a better outcome in unstable coronary artery disease

Unstable coronary artery disease is a term encompassing both unstable angina and non-Q-wave (non-ST-segment elevation) myocardial infarction. Patients with these conditions are at risk of early progression to acute myocardial infarction and death. Thus, management of these conditions must aim to reduce long-term mortality and morbidity. Risk stratification is crucial for the identification of patients whose risk of early progression is high; they may require coronary angiography and (if suitable) either percutaneous transluminal coronary angioplasty or coronary artery bypass surgery. No single variable can accurately predict risk, but considerable data are emerging to show that biochemical markers of myocardial injury, such as troponin-T and troponin-I, are valuable in combination with electrocardiographic findings and clinical features. Routine early invasive procedures (coronary angiography with or without revascularization) have not yet been shown to have any significant advantage over conservative regimens for the majority of patients. Antiplatelet, anticoagulant, and anti-ischemic agents remain the mainstay of treatment in the acute phase. New agents, such as glycoprotein IIb/IIIa receptor inhibitors and low-molecular-weight heparins, as well as antithrombins and Factor Xa inhibitors add to the treatments currently available. Thrombolytic agents are contraindicated in the absence of ST-segment elevation. After clinical stabilization, ongoing assessment should include exercise testing for all patients who are able; other imaging techniques should be used for patients unable to exercise. A profile indicating a high risk of future events is an indication for elective angiography and consideration for revascularization.

Regional differences in the characteristics and treatment of patients participating in an international heart failure trial. The Assessment of Treatment with Lisinopril and Survival (ATLAS) Trial Investigators

AIMS

This study was designed to determine regional differences in patient characteristics and medication use among patients entered into an international heart failure trial.

METHODS AND RESULTS

Data for this analysis were derived from the Assessment of Treatment with Lisinopril and Survival Study (ATLAS), a prospective randomized comparison of high- and low-dose therapy with lisinopril in patients with New York Heart Association class II, III, or IV chronic heart failure, which enrolled 3164 patients in 291 centers in 19 countries on 3 continents. Information was collected at baseline concerning patient demographics, etiology of heart failure, accompanying conditions, prior revascularization procedures, and medication use. The primary findings were a lower incidence of ischemic cardiomyopathy in southern and western Europe, more frequent diabetes in North America, and a greater use of coronary revascularization in the United States and Canada. There was substantial variation in medication use, particularly with regard to digoxin, anticoagulants, and amiodarone.

CONCLUSIONS

Although there is considerable overlap in guidelines concerning the treatment of heart failure issued by authorities in Europe and North America, there are significant regional variations in medication use. Some, but not all, of these differences can be explained by differences in patient characteristics.

Carvedilol for heart failure: more than just a beta-blocker?

Carvedilol is a non-selective beta-blocker, and the only one, in recent clinical trials, to have shown a clear reduction in mortality. It is suggested that, compared with other beta-blockers, carvedilol has additional advantageous effects in heart failure, and should be considered as part of the routine treatment of heart failure.