Effects of Prostacyclin and of the Stable Prostacyclin Analogue ZK 36374 on Forearm Blood Flow and Blood Platelet Behaviour in Man

PGI2 and ZK 36374 were each infused into volunteers and the effects on forearm blood flow and on platelet behaviour were determined. Infusions of PGI2 or ZK 36374 did not alter resting forearm blood flow but both agents reduced the extent of the vasoconstriction that occurred in response to cold. ZK 36374 appeared to be a much more potent inhibitor of platelet behaviour than PGI2 when blood was taken while the infusions were in progress, but the effects of both agents were no longer evident one hour after the infusions were terminated. There was an inverse relationship between the extent of cold-induced vasoconstriction and the concentration of sodium arachidonate that was needed to induce platelet aggregation for different individuals. Infusions of PGI2 affected both parameters equally but ZK 36374 had a greater effect on platelet behaviour than on blood flow. It is possible that very low doses of ZK 36374 would result in inhibition of platelet behaviour without producing adverse haemodynamic effects.

Drug therapy in chronic heart failure

Chronic heart failure is widely recognised as a common and escalating problem that causes major disability and often shortens life. Diuretics and digoxin have formed the mainstay of treatment for many years. Clinical trials have demonstrated that angiotensin converting enzymes and beta-blockers, in selected patients, improve symptoms and reduce mortality. Angiotensin-II antagonists and spironolactone may also have a role in certain individuals. Newer pharmacological approaches to the management of this complex disease are being developed, but await full evaluation.

Beneficial haemodynamic effects of insulin in chronic heart failure

OBJECTIVE

To characterise the central and regional haemodynamic effects of insulin in patients with chronic heart failure.

DESIGN

Single blind, placebo controlled study.

SETTING

University teaching hospital.

PATIENTS

Ten patients with stable chronic heart failure.

INTERVENTIONS

Hyperinsulinaemic euglycaemic clamp and non-invasive haemodynamic measurements.

MAIN OUTCOME MEASURES

Change in resting heart rate, blood pressure, cardiac output, and regional splanchnic and skeletal muscle blood flow.

RESULTS

Insulin infusion led to a dose dependent increase in skeletal muscle blood flow of 0.36 (0.13) and 0.73 (0.14) ml/dl/min during low and high dose insulin infusions (p < 0.05 and p < 0.005 v placebo, respectively). Low and high dose insulin infusions led to a fall in heart rate of 4.6 (1.4) and 5.1 (1.3) beats/min (p < 0.05 and p < 0.005 v placebo, respectively) and a modest increase in cardiac output. There was no significant change in superior mesenteric artery blood flow.

CONCLUSION

In patients with chronic heart failure insulin is a selective skeletal muscle vasodilator that leads to increased muscle perfusion primarily through redistribution of regional blood flow rather than by increased cardiac output. These results provide a rational haemodynamic explanation for the apparent beneficial effects of insulin infusion in the setting of heart failure.

Beneficial haemodynamic effects of insulin in chronic heart failure

OBJECTIVE

To characterise the central and regional haemodynamic effects of insulin in patients with chronic heart failure.

DESIGN

Single blind, placebo controlled study.

SETTING

University teaching hospital.

PATIENTS

Ten patients with stable chronic heart failure.

INTERVENTIONS

Hyperinsulinaemic euglycaemic clamp and non-invasive haemodynamic measurements.

MAIN OUTCOME MEASURES

Change in resting heart rate, blood pressure, cardiac output, and regional splanchnic and skeletal muscle blood flow.

RESULTS

Insulin infusion led to a dose dependent increase in skeletal muscle blood flow of 0.36 (0.13) and 0.73 (0.14) ml/dl/min during low and high dose insulin infusions (p < 0.05 and p < 0.005 v placebo, respectively). Low and high dose insulin infusions led to a fall in heart rate of 4.6 (1.4) and 5.1 (1.3) beats/min (p < 0.05 and p < 0.005 v placebo, respectively) and a modest increase in cardiac output. There was no significant change in superior mesenteric artery blood flow.

CONCLUSION

In patients with chronic heart failure insulin is a selective skeletal muscle vasodilator that leads to increased muscle perfusion primarily through redistribution of regional blood flow rather than by increased cardiac output. These results provide a rational haemodynamic explanation for the apparent beneficial effects of insulin infusion in the setting of heart failure.

Randomised comparison of losartan vs. captopril on quality of life in elderly patients with symptomatic heart failure: the losartan heart failure ELITE quality of life substudy

OBJECTIVE

To measure health-related quality-of-life (HRQoL) in elderly symptomatic heart failure patients following treatment with an angiotensin II receptor antagonist (losartan) vs. an angiotensin-converting-enzyme (ACE) inhibitor (captopril).

METHODS

Patients (age > or = 65 years) were randomised to losartan, titrated to 50 mg once daily, or captopril, titrated to 50 mg three times daily, as tolerated. Sickness Impact Profile (SIP) and Minnesota Living with Heart Failure (LIhFE) questionnaires were administered at baseline, weeks 12 and 48. Composite hypothesis testing of change in HRQoL from baseline for completers, and withdrawal for unfavourable events (death, clinical/laboratory adverse experience) was used to account for differential dropout rates.

RESULTS

In 203 patients completing the substudy (week 48), significant and comparable improvements in HRQoL from baseline were observed for both treatment groups (p < or = 0.001). Although there was a trend favouring losartan vs. captopril for the composite HRQoL endpoint (unadjusted p = 0.018, one-sided), this was not considered significant after adjusting for multiple testing. Significantly more captopril patients in the substudy subset withdrew for unfavourable reasons (19.6 vs. 10.9%, p = 0.038).

CONCLUSIONS

Significant improvements in HRQoL were observed in elderly patients with symptomatic heart failure treated with losartan and captopril long-term. A trend favouring losartan in the composite measure of drug tolerability/quality of life was not significant, but losartan was generally better tolerated than captopril in that significantly fewer losartan patients discontinued therapy.

Cognitive impairment in heart failure with Cheyne-Stokes respiration

OBJECTIVES

To document the degree of cognitive impairment in stable heart failure, and to determine its relation to the presence of Cheyne-Stokes respiration during sleep.

SUBJECTS

104 heart failure patients and 21 healthy normal volunteers.

METHODS

Overnight oximetry was used (previously validated as a screening tool for Cheyne-Stokes respiration in heart failure). Cognitive function was assessed using a battery of neuropsychological tests. Left ventricular function was assessed by echocardiography.

RESULTS

Heart failure patients performed worse than the healthy volunteers in tests that measured vigilance. Reaction times were 48% slower (0.89 (0.03) s v 0.60 (0.05) s p < 0.005) and they hit twice as many obstacles on the Steer Clear simulator (75 (6.4) v 33 (4.6); p < 0.005). Cognitive impairment within the heart failure group was unrelated to either the presence of Cheyne-Stokes respiration, the degree of left ventricular dysfunction, or indices of nocturnal oxygenation.

CONCLUSIONS

Vigilance was impaired in heart failure but this did not appear to be related to the presence of Cheyne-Stokes respiration during sleep. Impaired vigilance as measured on the Steer Clear test has been associated with an increased risk of motor vehicle accidents. The issue of fitness to drive in heart failure requires further attention.

Combined treatment with losartan and an ACE inhibitor in mild to moderate heart failure: results of a double-blind, randomized, placebo-controlled trial

BACKGROUND

Although the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in patients with heart failure are well recognized, there are theoretical advantages in combining ACE inhibition with angiotensin (AT)1 receptor antagonism.

METHODS

Twenty patients with mild to moderate heart failure and maximally treated with an ACE inhibitor were randomly assigned to losartan or placebo. Patients underwent repeated assessment of exercise tolerance, quality of life, central and regional hemodynamics, and neurohumoral and biochemical parameters over a period of 12 weeks.

RESULTS

Losartan treatment was well tolerated in terms of adverse events, heart rate, and blood pressure response, and there were no significant changes in serum creatinine or potassium. After 12 weeks of treatment, no significant differences were observed between the losartan and placebo groups in exercise tolerance, quality of life, central and regional hemodynamics, or neurohumoral parameters.

CONCLUSIONS

In patients with mild to moderate heart failure already maximally treated with an ACE inhibitor, additional treatment with losartan is well tolerated, but we have not observed any significant improvement in exercise capacity, quality of life, central and regional hemodynamics, or neurohormones. Our data suggest that the combination of losartan with an ACE inhibitor does not offer any substantial advantages over treatment with an ACE inhibitor alone in these patients.

Haemodynamic, neurohumoral and exercise effects of losartan vs. captopril in chronic heart failure: results of an ELITE trial substudy. Evaluation of Losartan in the Elderly

BACKGROUND

The AT1 receptor antagonists differ from the angiotensin converting enzyme inhibitors by achieving a more complete blockade of angiotensin II's actions and by not affecting bradykinin metabolism. There is little information on whether this causes clinically significant differences in haemodynamics, neurohormones and exercise tolerance in heart failure.

AIMS

To compare the effects of losartan and captopril upon central and regional haemodynamics, neurohormones and exercise capacity in heart failure.

METHODS

In a double-blind, randomised trial 18 patients aged > or =65 years with symptomatic heart failure were allocated to treatment with losartan (10 patients) or captopril (eight patients). Patients underwent assessment at baseline, after the first dose, at 12 weeks and at 24 weeks.

RESULTS

Systolic blood pressure fell by - 10.7% 1 h after captopril 6.25 mg (P = 0.007) and by - 4.8% 3 h after losartan 12.5 mg (P = 0.02). The blood pressure reduction was sustained with losartan at 12 and 24 weeks. Systemic vascular resistance fell acutely after captopril (-16.4%, P = 0.01). Captopril caused an acute and sustained rise in superior mesenteric artery blood flow (+ 22.9%, P = 0.04), and a slower rise in renal artery blood flow (+31.7%, P = 0.01). Losartan had no acute effects on regional haemodynamics but had increased superior mesenteric artery blood flow by 38.1% at 12 weeks (P = 0.02). There were no substantial differences between losartan and captopril, and no changes occurred in neurohormones or exercise capacity.

CONCLUSION

No substantial differences were observed between losartan and captopril on central or regional haemodynamics, neurohormones or exercise capacity in elderly patients with stable symptomatic heart failure.

The relationship between QT intervals and mortality in ambulant patients with chronic heart failure. The united kingdom heart failure evaluation and assessment of risk trial (UK-HEART)

AIMS

Mortality in patients with heart failure remains high and is difficult to predict. QT interval parameters on a 12-lead ECG have been shown to predict arrhythmic events in patients with a variety of myocardial diseases. There is some, but not consistent, evidence that QT interval parameters may act as predictors of mortality, in particular sudden death, in patients with heart failure. In an adequately powered prospective study we have studied QT interval parameters in patients with stable chronic heart failure in order to determine whether they are predictive of all-cause mortality or mode of death.

METHODS AND RESULTS

Five hundred and fifty-four ambulant outpatients with chronic heart failure were recruited. A 12-lead ECG, chest radiograph, echocardiogram, 24 h ambulatory electrocardiogram and serum for biochemical analysis were obtained at baseline. Patients were followed for 471+/-168 days. QT intervals were measured in all leads blinded to patient's characteristics and outcome, were corrected for heart rate, and the maximum QT intervals, and QT dispersion (range of QT intervals) were determined. The same parameters were determined for JT intervals. The primary end-point was all-cause mortality, secondary end-points were sudden cardiac death and death due to progressive heart failure. Multivariate analysis with the Cox's proportional hazards model was used to determine which variables were independently related to outcome. Four hundred and ninety-five patients had analysable ECGs at study entry and of these 71 died during follow-up. The heart rate corrected QT dispersion and maximum QT interval were significant univariate predictors of all-cause mortality (P=0.026 and <0.0001 respectively), and also of sudden death and progressive heart failure death, but were not related to outcome in the multivariate analysis. The independent predictors of all-cause mortality were cardiothoracic ratio (P=0.0003), creatinine (P=0.0009), heart rate (P=0.007), echocardiographically derived left ventricular end-diastolic dimension (P=0.007) and ventricular couplets on 24 h electrocardiographic monitoring (P=0.015).

CONCLUSION

In an adequately powered prospective study none of the QT or JT parameters were shown to be independent predictors of outcome in patients with mild to moderate congestive heart failure. These variables do not therefore add to the prognostic information which can be gained from simple radiographic, biochemical, echocardiographic and Holter data in this group of patients.

Effects of losartan and captopril on QT dispersion in elderly patients with heart failure. ELITE study group

Differences in QT dispersion (a predictor for sudden death) were observed in a subgroup of patients in the ELITE heart failure study of losartan compared with captopril, and may explain improved survival with losartan.

Achieving appropriate endpoints in heart failure trials: the PRIME-II protocol. The Second Perspective Randomised study of Ibopamine on Mortality and Efficacy

Many clinical trials unintentionally include patients with a low risk of the trial endpoints. PRIME II (The Second Perspective Randomised study of Ibopamine on Mortality and Efficacy) was a large international randomised double blind trial comparing the addition of ibopamine or placebo to the therapy of patients with advanced heart failure. The trial was stopped prematurely because ibopamine was associated with an increased fatality rate, but the protocol achieved its objective of including high-risk patients. Here we describe the protocol details that enabled patients with the desired degree of risk to be included. We also amplify our definition of mode of death. The PRIME II protocol was designed with the intention that patients in the placebo group would have an annual fatality rate of 20%. Since the study was to be conducted in some 200 centres in 13 European countries, the inclusion criteria had to be simple and flexible, allowing for different clinical practice. The inclusion criteria, together with the use of simple investigations (which did not have to include angiographic or radionuclide ventriculography) are described. The annual fatality rate in the placebo group was just over 20%. Six categories of mode of death were used, but while they were reasonably easy to apply they did not reveal the reason for the unexpected adverse effect of ibopamine. The inclusion and exclusion criteria used for PRIME II, and the definitions of mode of death, were effective. The PRIME II protocol can be used as a model for future heart failure studies.

Ventricular dilatation in the absence of ACE inhibitors: influence of haemodynamic and neurohormonal variables following myocardial infarction

OBJECTIVE

To examine the relation between patterns of ventricular remodelling and haemodynamic and neurohormonal variables, at rest and during symptom limited exercise, in the year following acute myocardial infarction in patients not receiving angiotensin converting enzyme (ACE) inhibitors.

DESIGN

A prospective observational study.

PATIENTS

65 patients recruited following hospital admission with a transmural anterior myocardial infarction.

METHODS

Central haemodynamics and neurohormonal activation at rest and during symptom limited treadmill exercise were measured at baseline before hospital discharge, one month later, and at three monthly intervals thereafter. PATIENTS were classified according to individual patterns of change in left ventricular end diastolic volumes at rest, assessed at each visit using transthoracic echocardiography.

RESULTS

In most patients (n = 43, 66%) ventricular volumes were unchanged or reduced. Mean (SEM) treadmill exercise capacity and peak exercise cardiac index increased at month 12 by 200 (24) seconds (p < 0.001 v baseline) and by 0.8 (0.4) l/min/m2 (p<0.05 v baseline), respectively, in this group. In patients with limited ventricular dilatation (n = 11, 17%) exercise capacity increased by 259 (52) seconds (p < 0.001 v baseline) and peak exercise cardiac index improved by 0.8 (0.7) l/min/m2 (NS). In the remaining 11 patients with progressive left ventricular dilatation, exercise capacity increased by 308 (53) seconds (p< 0. 001 v baseline) and peak exercise cardiac index similarly improved by 1.3 (0.7) l/min/m2 (NS). There were trends towards increased atrial natriuretic factor (ANF) secretion at rest and at peak exercise in this group.

CONCLUSIONS

Ventricular dilatation after acute myocardial infarction is a heterogeneous process that is progressive in only a minority of patients. Compensatory mechanisms, including ANF release, appear capable of maintaining and improving exercise capacity in most patients for at least 12 months, even in those with a progressive increase in ventricular size.

Failure of an ACE inhibitor to improve exercise tolerance. A randomized study of trandolapril. Trandolapril study group

BACKGROUND

There has been conflicting evidence of the effect of angiotensin-converting enzyme (ACE) inhibitors on exercise tolerance. Meta-analysis of published results has suggested that a beneficial effect of ACE inhibitors is demonstrated if a trial design is adequate.

SETTING

Multicentre International Trial.

METHODS

In a double-blind, randomized, multicentre trial, 292 patients with moderate (New York Heart Association Grades II and III) heart failure were treated with trandolapril or placebo in addition to diuretics, and followed for 16 weeks. Exercise tolerance on a treadmill was assessed at baseline and after 4, 8, 12 and 16 weeks of treatment. Both a modified Bruce and a modified Naughton protocol were used.

RESULTS

Exercise tolerance improved in both treatment groups, with no significant benefit from trandolapril treatment.

CONCLUSION

Trandolapril does not improve exercise tolerance as measured by treadmill testing.

"Value" of improved treadmill exercise capacity: lessons from a study of rate responsive pacing

OBJECTIVES

To compare the value of a series of cardiovascular measurements in patients with symptomatic disease receiving an effective treatment (rate responsive pacing).

PATIENTS

12 pacemaker dependent patients with VVIR units.

INTERVENTIONS

Single blind crossover between VVI and VVIR.

OUTCOME MEASURES

Exercise capacity was assessed by treadmill tests (modified Bruce protocol and a fixed workload protocol) with respiratory gas analysis. Self paced corridor walk tests were also undertaken. Quality of life (QOL) was assessed by questionnaire. Daily activity was measured in the patients' homes using shoe and belt pedometers.

RESULTS

Treadmill tests and QOL questionnaires correctly identified the clinical benefit associated with VVIR. The modified Bruce protocol was superior to the fixed workload protocol as it was better tailored to the fairly well preserved exercise capacity of the patients. Symptom scores, but not walking times, were improved with VVIR during corridor walk tests. VVIR did not improve daily activity measured using either the belt or shoe pedometers.

CONCLUSIONS

VVIR pacing improved some but not all measures of exercise capacity. This finding illustrates the difficulty of selecting an instrument to measure symptomatic improvement in clinical research; and raises the question, what is the best way of measuring exercise capacity?

A randomized controlled trial of inspiratory muscle training in stable chronic heart failure

AIMS

To assess whether a domiciliary programme of specific inspiratory muscle training in stable chronic heart failure results in improvements in exercise tolerance or quality of life.

METHODS AND RESULTS

We conducted a randomized controlled trial of 8 weeks of inspiratory muscle training in 18 patients with stable chronic heart failure, using the Threshold trainer. Patients were randomized either to a training group inspiring for 30 min daily at 30% of maximum inspiratory mouth pressure, or to a control group of 'sham' training at 15% of maximum inspiratory mouth pressure. Sixteen of the 18 patients completed the study. Maximum inspiratory mouth pressure improved significantly in the training group compared with controls, by a mean (SD) of 25.4 (11.2) cmH2O (P=0.04). There were, however, no significant improvements in treadmill exercise time, corridor walk test time or quality of life scores in the trained group compared with controls.

CONCLUSION

Despite achieving a significant increase in inspiratory muscle strength, this trial of simple domiciliary inspiratory muscle training using threshold loading at 30% of maximum inspiratory mouth pressure did not result in significant improvements in exercise tolerance or quality of life in patients with chronic heart failure.

Effect of oxygen on sleep quality, cognitive function and sympathetic activity in patients with chronic heart failure and Cheyne-Stokes respiration

BACKGROUND

Cheyne-Stokes respiration disrupts sleep, leading to daytime somnolence and cognitive impairment. It is also an independent marker of increased mortality in heart failure. This study evaluated the effectiveness of oxygen therapy for Cheyne-Stokes respiration in heart failure.

METHODS

Eleven patients with stable heart failure and Cheyne-Stokes breathing were studies. Oxygen and air were administered for 4 weeks in a double-blind, cross-over study. Sleep and disordered breathing was assessed by polysomnography. Symptoms were assessed using the Epworth Sleepiness Scale, visual analogue and quality of lift scores. Cognitive function was assessed by neuropsychometric testing. Overnight urinary catecholamine excretion was used as a measure of sympathetic nerve activity.

RESULTS

Ninety-seven percent of apnoeas were central in origin. Oxygen therapy reduced the central apnoea rate (18.4 +/- 4.1 vs 3.8 +/- 2.1 per hour; p = 0.05) and periodic breathing time (33.6 +/- 7.4 vs 10.7 +/- 3.9% of actual sleep time; p = 0.003). Oxygen did not improve sleep quality, patient symptoms or cognitive failure. Oxygen reduced urinary noradrenaline excretion (8.3 +/- 1.5 vs 4.1 +/- 0.6 nmol.mmol-1 urinary creatinine; p = 0.03).

CONCLUSION

Oxygen stabilized sleep disordered breathing and reduced sympathetic activity in patients with heart failure and Cheyne-Stokes respiration. We were unable to demonstrate an effect on either patient symptoms or cognitive function.

The effect of dietary creatine supplementation on skeletal muscle metabolism in congestive heart failure

AIMS

To assess the effects of dietary creatine supplementation on skeletal muscle metabolism and endurance in patients with chronic heart failure.

METHODS

A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction was measured using handgrip dynanometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of maximum voluntary contraction or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg and 21 kg. Patients were assigned to creatine 20 g daily or matching placebo for 5 days and returned after 6 days for repeat study.

RESULTS

Contractions (median (25th, 75th interquartiles)) until exhaustion at 75% of maximum voluntary contraction increased after creatine treatment (8 (6, 14) vs 14 (8, 17), P = 0.025) with no significant placebo effect. Ammonia per contraction at 75% maximum voluntary contraction (11.6 mumol/l/contraction (8.3, 15.7) vs 8.9 mumol/l/contraction (5.9, 10.8), P = 0.037) and lactate per contraction at 75% maximum voluntary contraction (0.32 mmol/l/contraction (0.28, 0.61) vs 0.27 mmol/l/contraction (0.19, 0.49), P = 0.07) fell after creatine but not after placebo.

CONCLUSIONS

Creatine supplementation in chronic heart failure augments skeletal muscle endurance and attenuates the abnormal skeletal muscle metabolic response to exercise.

Nocturnal desaturation in patients with stable heart failure

OBJECTIVE

To determine the prevalence of sleep disordered breathing within a United Kingdom heart failure population.

SUBJECTS

104 patients and 21 matched normal volunteers.

METHODS

Overnight home pulse oximetry with simultaneous ECG recording in the patient group; daytime sleepiness was assessed using the Epworth sleepiness scale (ESS); 41 patients underwent polysomnography to assess the validity of oximetry as a screening test for Cheyne-Stokes respiration.

RESULTS

Home oximetry was a good screening test for Cheyne-Stokes respiration (specificity 81%, sensitivity 87%). Patients with poorer New York Heart Association (NYHA) classes had higher sleepiness scores (p < 0.005). Twenty three patients had "abnormal" patterns of nocturnal desaturation suggestive of Cheyne-Stokes respiration. The mean (SEM) frequency of dips in Sao2 exceeding 4% was 10.3 (0.9) per hour in the patients and 4.8 (0.6) in normal controls (p < 0.005). Ejection fraction correlated negatively with dip frequency (r = -0.5, p < 0.005). The patient subgroup with > or = 15 dips/hour had a higher mean (SEM) NYHA class (3.0 (0.2) v 2.3 (0.1), p < 0.05), and experienced more ventricular ectopy (220 (76) v 78 (21) beats/hour, p < 0.05). There was no excess of serious arrhythmia.

CONCLUSIONS

Nocturnal desaturation is common in patients with treated heart failure. Low ejection fraction was related to dip frequency. Lack of correlation between dips and ESS suggests that arousal from sleep is more important than hypoxia in the aetiology of daytime sleepiness in heart failure. Overnight oximetry is a useful screening test for Cheyne-Stokes respiration in patients with known heart failure.

Endogenous insulin and insulin sensitivity. An important determinant of skeletal muscle blood flow in chronic heart failure?

AIM

Patients with heart failure have a reduced sensitivity to insulin's actions on glucose metabolism and a compensatory increase in endogenous plasma insulin levels. As insulin has a selective vasodilatory action in skeletal muscle, we have studied the association between insulin sensitivity and central and regional haemodynamics in patients with heart failure.

METHODS

Ten patients with stable symptomatic heart failure were studied. We used non-invasive techniques to measure cardiac output, forearm blood flow, superior mesenteric artery blood flow and right renal artery blood flow. Blood samples were assayed for noradrenaline, renin and atrial natriuretic peptide levels. Insulin sensitivity was assessed using the low dose short insulin tolerance test.

RESULTS

There was a significant inverse correlation between forearm blood flow and insulin sensitivity (r = -0.67, P = 0.03), patients with lesser degrees of insulin sensitivity having the greater forearm blood flows. There was no correlation with the other haemodynamic or neurohumoral parameters. Patients with greater insulin resistance tended to have higher circulating endogenous insulin levels, although this relationship did not reach statistical significance (r = -0.53, P = 0.12).

CONCLUSIONS

Insulin sensitivity appears to be an important determinant of skeletal muscle blood flow in heart failure. We speculate that this is secondary to the increased circulating endogenous insulin levels, and suggest that the therapeutic potential of exogenous insulin merits further investigation.

Depressor action of insulin on skeletal muscle vasculature: a novel mechanism for postprandial hypotension in the elderly

OBJECTIVES

We sought to assess the role of insulin in postprandial blood pressure regulation in the elderly.

BACKGROUND

Insulin is both a positive inotropic and chronotropic hormone that also vasodilates skeletal muscle vasculature. Insulin may thus mediate aspects of postprandial cardiovascular homeostasis.

METHODS

Ten healthy elderly subjects were studied in the fasting state on three separate days. After baseline supine hemodynamic and neurohumoral measurements were taken (cardiac output and superior mesenteric artery blood flow were measured using Doppler ultrasound, and calf blood flow was measured using venous occlusion plethysmography), subjects ate on one occasion a 2.5-MJ high carbohydrate meal and on the other two occasions, an isoenergetic high fat meal. One high fat meal was accompanied by an insulin infusion reproducing the plasma insulin profile seen after a high carbohydrate meal while maintaining the glycemic profile seen after a high fat meal alone. After meal ingestion, measurements were repeated every 20 min for 2 h.

RESULTS

After the three meals, there were similar increments in cardiac output and heart rate. After the high carbohydrate meal and high fat meal with insulin, mean arterial blood pressure fell by between 8 to 10 mm Hg, but did not change after the high fat meal. After the high carbohydrate meal and the high fat meal with insulin, calf vascular resistance did not change, whereas after the high fat meal, it increased by 15.5 +/- 4.4 U (mean +/- SEM).

CONCLUSIONS

Insulin contributes to the failure of calf vasoconstriction seen after a high carbohydrate meal. By this vasodepressor action, insulin is at least in part responsible for the fall in blood pressure after a high carbohydrate meal.

Incremental threshold loading: a standard protocol and establishment of a reference range in naive normal subjects

Incremental threshold loading (ITL) has been proposed as a test of inspiratory muscle strength and endurance. To date, however, there has been no standardized protocol for an ITL test, and no reference range, with different investigators using a variety of different pressure increments in small numbers of subjects. We developed an ITL test using the weighted plunger (WP) principle, which uses standard increments of pressure. In our protocol subjects inspire through the WP generating an initial threshold opening pressure of 10 cmH2O. This pressure is raised at 2 min intervals in increments of 5 cmH2O until they fail to lift the plunger on two consecutive attempted breaths. Sixty healthy volunteers (30 males and 30 females) aged 20-80 yrs performed the ITL test. Twelve subjects (six females and six males) performed the test twice to assess reproducibility and repeatability. Using stepwise multiple linear regression, we regressed the maximum threshold pressure sustained for a full 2 min (Pmax) against age, height, weight and static maximum inspiratory mouth pressure (MIP). Pmax was significantly related to age but not to either height or weight, the regression equation for males was Pmax (cmH2O)=103.8 - (1.0 x age in years), and for females was Pmax (cmH2O)=93.7 - (1.0 x age in years). The within-subject standard deviation for those repeating the ITL test was 5.4 cmH2O. Incremental threshold loading is a simple technique with good reproducibility, which most naive subjects can use without difficulty. By using standard pressure increments and performing the test in a large number of naive subjects, we have established a reference range that should be applicable wherever similar pressure increments are used.

A carbohydrate meal attenuates the forearm vasoconstrictor response to lower body subatmospheric pressure in healthy young adults

The cardiovascular (CV) responses to meal ingestion and orthostasis are well established. The effect of meal ingestion and meal composition on the CV responses to orthostasis are unknown. The effect of high carbohydrate (HC) and high fat (HF) meal ingestion on the CV responses to simulated orthostatic stress (using graded lower body subatmospheric pressure (LBSP)) was assessed in nine healthy young volunteers. Cardiac output (CO), forearm blood flow (FABF) heart rate (HR) and blood pressure (BP) were measured before and during LBSP while fasted and after eating HC and HF meals. Ingestion of both meals led to an increase in CO and HR. Both meals resulted in a fall in total peripheral resistance but only HC led to a significant fall in BP (p < 0.05). HF had no effect on the CV responses to LBSP, whereas HC resulted in attenuated FABF and forearm vascular resistance responses (p < 0.05). Thus, ingestion of an HC meal significantly attenuates the forearm vascular response to orthostatic stress and the hypotensive effect of orthostasis is additive to that occurring after an HC meal.

Effects of amlodipine in patients with chronic heart failure

The role of calcium antagonists in patients with ischemic heart failure is currently unclear. We examined the effects of amlodipine on exercise capacity and central and regional hemodynamics in 32 patients with mild to moderate chronic heart failure in a single-center, double-blind, randomized placebo-controlled trial. All were taking at least 40 mg of furosemide daily with an angiotensin-converting enzyme inhibitor. Ischemic heart disease was the most common cause of heart failure, but no patient had symptom-limiting angina. Mean treadmill exercise capacity in patients taking amlodipine increased by 96 seconds (95% confidence interval -23 to 215) and 50 seconds (-34 to 135) in the placebo group; mean difference in change between treatments was 70 seconds (-90 to 233), p = 0.38. Active treatment with amlodipine did not affect self-paced corridor walking times. Similarly, there were no significant effects on cardiac output, oxygen uptake, heart rate, and mean arterial pressure at rest or during exercise. Calf and renal blood flow were also unchanged by treatment. The lack of significant effect demonstrated by these data suggests a limited role for amlodipine in patients with ischemic cardiomyopathy, although it may prove beneficial in those with nonischemic disease. More data are required before amlodipine can be recommended for all patients with chronic heart failure.

Should general practitioners use the electrocardiogram to select patients with suspected heart failure for echocardiography?

Patient referrals from general practice for suspected heart failure are increasing the demand for echocardiograms, many of which are normal. We investigated whether general practitioners could be more selective by referring only patients with abnormal electrocardiograms for echocardiography. The electrocardiograms of 200 patients attending a heart failure clinic were analysed by a consultant cardiologist and two general practitioners. All three assessors examined the electrocardiograms independently and unaware of the echocardiography results. The correlation between abnormal electrocardiograms and left ventricular systolic dysfunction on echocardiography was assessed, together with the concordance between the assessors in their electrocardiogram interpretations. One hundred and sixty-five patients had echocardiographic evidence of left ventricular systolic dysfunction. When interpreted by a cardiologist, the electrocardiogram had a sensitivity of 89.1% and a specificity of 45.7% in predicting left ventricular systolic dysfunction. The general practitioners' results were comparable to the cardiologist's. We estimate that using the electrocardiogram to select patients could reduce the number of open access echocardiograms performed for suspected heart failure by up to 43% but would miss 10% of those with significant left ventricular systolic dysfunction. We therefore do not recommend selecting patients for open access echocardiography on the basis of electrocardiographic abnormalities.

Relation of daily activity levels in patients with chronic heart failure to long-term prognosis

Symptom-limited, laboratory-based exercise tests are often used to define prognosis in patients with chronic heart failure, but they do not relate to measures of normal daily activity. Invasive measures of central hemodynamics similarly relate poorly to outcome. Pedometer scores of weekly walking are markedly reduced in patients with heart failure, but whether this less artificial measure of exercise capacity is important in predicting prognosis is not known. Eighty-four patients with chronic heart failure were followed for a mean of 710 days during which 44 died and 3 underwent cardiac transplantation. Symptom-limited treadmill exercise capacity using 2 different protocols did not predict survival, whereas reduced weekly pedometer scores were strong predictors of death (p < 0.001). Other variables that predicted death included resting cardiac output, arterial blood pressure, diuretic requirements, New York Heart Association class, increased bilirubin, and hyponatremia (all p < 0.01). Reduced levels of daily activity are strong predictors of death in chronic heart failure and appear more powerful than laboratory-based exercise tests. This type of assessment is valuable in identifying patients at high risk and provides an objective measure of incapacity during normal daily life. The exercise capacity of patients unable to exercise in the laboratory could also be assessed using this technique. This may prove invaluable in clinical and mortality trials.

A double-blind, cross-over comparison of the effects of a loop diuretic and a dopamine receptor agonist as first line therapy in patients with mild congestive heart failure

We compared the effects of the orally active dopamine agonist ibopamine with the loop diuretic frusemide as first-line therapy in patients with mild congestive heart failure. Fourteen patients with New York Heart Association class II congestive heart failure were enrolled in a double-blind, cross-over study. After baseline measurements of clinical and symptomatic status, modified Bruce exercise time, high-level exercise time, corridor walk time, regional blood flow, pedometer scores, 24 h urine volume and sodium excretion and neurohumoural factors, patients were randomly allocated to receive either frusemide 40 mg o.d. or ibopamine 100 mg t.d.s. for 8 weeks. Assessments were performed at 2 weekly intervals. After 8 weeks, patients crossed over into the alternate treatment arm for a further 8 weeks, with further assessments performed every 2 weeks. There were four exacerbations of heart failure during ibopamine treatment and none during frusemide treatment. After 8 weeks of treatment, modified Bruce exercise time was 901 +/- 73 s with frusemide and 646 +/- 134 s with ibopamine (P < 0.05). Twenty-four hour urinary sodium excretion at weeks 2 and 4 (P < 0.05), and 24 h urinary volume at week 2 (P = 0.0001) were lower during ibopamine treatment. At week 8, supine (P = 0.076) and erect renin (P = 0.05) were lower with ibopamine treatment. In conclusion, ibopamine is ineffective as first line therapy for congestive heart failure, probably because of a lesser diuretic potency than frusemide.

Randomised study of effect of ibopamine on survival in patients with advanced severe heart failure. Second Prospective Randomised Study of Ibopamine on Mortality and Efficacy (PRIME II) Investigators

BACKGROUND

Drugs that improve symptoms in patients with heart failure must also be assessed for their effects on survival. Ibopamine stimulates DA-1 and DA-2 receptors and causes peripheral and renal vasodilatation; the drug improves symptoms of heart failure. We assessed the effect of ibopamine on survival in patients with advanced heart failure in a multicentre, randomised placebo-controlled study.

METHODS

Patients with advanced severe heart failure (New York Heart Association classes III and IV) and evidence of severe left-ventricular disease, who were already receiving optimum treatment for heart failure, were randomly allocated oral ibopamine 100 mg three times daily or placebo. The primary endpoint was all-cause mortality. The study was designed to recruit 2200 patients, and the minimum duration of treatment would be 6 months. We did intention-to-treat and on-treatment analyses; a post-hoc subgroup analysis was also done.

FINDINGS

After we had recruited 1906 patients the trial was stopped early, because of an excess of deaths among patients in the ibopamine group. 232 (25%) of 953 patients in the ibopamine group died, compared with 193 (20%) of 953 patients in the placebo group (relative risk 1.26 [95% CI 1.04-1.53], p = 0.017). The average length of follow-up was 347 days in the ibopamine group and 363 days in the placebo group. In multivariate analysis, only the use of antiarrhythmic drugs at baseline was a significant independent predictor of increased fatality in ibopamine-treated patients.

INTERPRETATION

Ibopamine seems to increase the risk of death among patients with advanced heart failure who are already receiving optimum therapy, but the reasons for this increase are not clear. Our finding that antiarrhythmic treatment was a significant predictor of increased mortality in ibopamine-treated patients may be important, but exploratory analyses must be interpreted with caution.

Randomised trial of losartan versus captopril in patients over 65 with heart failure (Evaluation of Losartan in the Elderly Study, ELITE)

BACKGROUND

To determine whether specific angiotensin II receptor blockade with losartan offers safety and efficacy advantages in the treatment of heart failure over angiotensin-converting-enzyme (ACE) inhibition with captopril, the ELITE study compared losartan with captopril in older heart-failure patients.

METHODS

We randomly assigned 722 ACE inhibitor naive patients (aged 65 years or more) with New York Heart Association (NYHA) class II-IV heart failure and ejection fractions of 40% or less to double-blind losartan (n = 352) titrated to 50 mg once daily or captopril (n = 370) titrated to 50 mg three times daily, for 48 weeks. The primary endpoint was the tolerability measure of a persisting increase in serum creatinine of 26.5 mumol/L or more (> or = 0.3 mg/dL) on therapy; the secondary endpoint was the composite of death and/or hospital admission for heart failure; and other efficacy measures were total mortality, admission for heart failure, NYHA class, and admission for myocardial infarction or unstable angina.

FINDINGS

The frequency of persisting increases in serum creatinine was the same in both groups (10.5%). Fewer losartan patients discontinued therapy for adverse experiences (12.2% vs 20.8% for captopril, p = 0.002). No losartan-treated patients discontinued due to cough compared with 14 in the captopril group. Death and/or hospital admission for heart failure was recorded in 9.4% of the losartan and 13.2% of the captopril patients (risk reduction 32% [95% CI -4% to + 55%], p = 0.075). This risk reduction was primarily due to a decrease in all-cause mortality (4.8% vs 8.7%; risk reduction 46% [95% CI 5-69%], p = 0.035). Admissions with heart failure were the same in both groups (5.7%), as was improvement in NYHA functional class from baseline. Admission to hospital for any reason was less frequent with losartan than with captopril treatment (22.2% vs 29.7%).

INTERPRETATION

In this study of elderly heart-failure patients, treatment with losartan was associated with an unexpected lower mortality than that found with captopril. Although there was no difference in renal dysfunction, losartan was generally better tolerated than captopril and fewer patients discontinued losartan therapy. A further trial, evaluating the effects of losartan and captopril on mortality and morbidity in a larger number of patients with heart failure, is in progress.

Why are angiotensin converting enzyme inhibitors underutilised in the treatment of heart failure by general practitioners?

Treatment with angiotensin converting enzyme inhibitors confers significant morbidity and mortality benefits in patients with heart failure, yet previous studies have repeatedly shown that these drugs are underutilised in general practice. To investigate why this is the case, we conducted an anonymous questionnaire survey of 515 general practitioners in the Nottingham Health District. The response rate was 60.2%. We found that although 39.3% of respondents underestimated the poor prognosis associated with heart failure, 98% were aware of the prognostic benefits conferred by angiotensin converting enzyme inhibitors. However, 46.3% of respondents expressed concern about the potential adverse effects associated with angiotensin converting enzyme inhibitors, the main fears being hypotension and renal impairment. General practitioners who were concerned about adverse effects were significantly less likely to have initiated an angiotensin converting enzyme inhibitor for heart failure than those who were not (P<0.01). Further research is needed to identify which patients can safely be commenced on angiotensin converting enzyme inhibitors in general practice. In the meantime, general practitioners should be encouraged to refer patients whenever they are concerned about initiating angiotensin converting enzyme inhibitors in the community.

Abnormalities of skeletal muscle metabolism in patients with chronic heart failure: evidence that they are present at rest

OBJECTIVE

To investigate abnormalities of skeletal muscle metabolism in patients with congestive heart failure.

SETTING

A university teaching hospital.

METHODS

43 patients (22 New York Heart Association (NYHA) grade II, 21 grade III) and 10 controls were studied. A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction (MVC) was measured using handgrip dynamometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of MVC or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg, and 21 kg.

RESULTS

MVC (kg, mean (SEM)) was lower in patients than in controls (control 42.45 (2.3); NYHA II 34.13 (1.3), P = 0.003; NYHA III 33.13 (1.94), P = 0.008). Resting lactate (mmol/l) was higher in patients than controls (control 0.65 (0.06); NYHA II 0.84 (0.08), P = 0.13; NYHA III 1.18 (0.1), P = 0.002). Resting ammonia (mumol/l) was higher in NYHA III (65.7 (6.0)) than in NYHA II (48.0 (3.7), P = 0.016); no difference was found between controls (48.0 (7.1)) and patients. The overall lactate and ammonia response to exercise was greater in NYHA III than in NYHA II and controls (P < 0.05). At volitional exhaustion, peak lactate (mmol/l: NYHA III 3.31 (0.26); NYHA II 2.56 (0.16); controls 2.71 (0.22); P = 0.022 NYHA III v NYHA II) and ammonia (mumol/l: NYHA III) 126.4 (8.97); NYHA II 92.9 (7.23); controls 109 (16.3); P = 0.006 NYHA III v NYHA II) were higher in severe congestive heart failure.

CONCLUSIONS

Skeletal muscle metabolism is abnormal at rest in congestive heart failure. During exercise, the degree of metabolic abnormality is related to the symptomatic status of the patient.

William Heberden revisited: postprandial angina-interval between food and exercise and meal composition are important determinants of time to onset of ischemia and maximal exercise tolerance

OBJECTIVES

This study aimed to explore the hemodynamic responses to ingestion of meals of different composition in patients with chronic stable angina and to assess the effect of these meals on time to onset of > 1-mm ST segment depression and limiting angina pectoris during exercise.

BACKGROUND

To our knowledge, no study has assessed the effect of meal composition and timing of exercise in patients with coronary artery disease.

METHODS

Fifteen patients with chronic stable angina visited our laboratory in the fasted state on three occasions. Measurements of cardiac output, heart rate and blood pressure were taken while patients were standing. A modified Bruce exercise test was then carried out, during which time to onset of > 1-mm ST segment depression and limiting chest pain were recorded. Patients then ate a 2.5-MJ high fat or high carbohydrate meal; on the third occasion, no meal was taken. At 30 min and 1 h after eating the meals, rest hemodynamic measurements and exercise tests were repeated.

RESULTS

The high fat meal did not affect exercise variables, whereas the high carbohydrate meal resulted in a reduction in time to onset of ST segment depression of 74.4 +/- 22.2 s (mean +/- SEM) during exercise at 30 min (p < 0.01), and at both 30 and 60 min after the high carbohydrate meal, limiting chest pain occurred 50 to 90 s earlier than when patients fasted (p < 0.01).

CONCLUSIONS

One hour after a high carbohydrate meal, the onset of angina during exercise occurs earlier than in the fasted state. Despite similar hemodynamic adjustments, a high fat meal does not affect exercise time.

Managing heart failure in a specialist clinic

Patients with heart failure are often inadequately investigated and treated in general practice. To improve the management of heart failure locally we initiated a specialist clinic in 1994. After its first 18 months, we audited the outcome of general practitioners' referrals to the clinic to examine its effectiveness in improving the diagnosis and treatment of heart failure. Eighty-five patients were referred with suspected heart failure. However, only 48% had echocardiographic evidence of left ventricular systolic dysfunction. Following referral, 80% of these patients were given a trial of angiotensin-converting enzyme inhibitors compared with 27% before referral. Six patients were receiving angiotensin-converting enzyme inhibitors unnecessarily, and five patients had significant structural cardiac disorders. Referral to a specialist clinic improved the accuracy of diagnosis and the number of patients on appropriate treatment. Greater use of open access echocardiography prior to referral might have allowed a more selective (and cost-effective) utilisation of the clinic.

Breathlessness and exercise capacity in heart failure: the role of bronchial obstruction and responsiveness

The cause of the breathlessness and reduced exercise capacity that occur in patients with chronic heart failure remains obscure. We examined the hypothesis that airway obstruction and bronchial hyper-responsiveness, which are recognised features of chronic heart failure, might contribute to the breathlessness and reduced exercise capacity in this condition. We studied 37 patients (7 female) with chronic heart failure, of mean age 61 years. Each patient underwent: (i) lung function testing with spirometry and expiratory flow volume loops. (ii) Measurement of bronchial responsiveness to methacholine. (iii) Symptom-limited treadmill exercise capacity using both incremental and fixed workload protocols, with measurement of Borg scores for breathlessness. Lung function was not significantly related to either exercise time, or Borg symptom scores in either exercise protocol. Bronchial hyper-responsiveness to methacholine was demonstrated in 12 patients. Exercise time did not correlate with the degree of bronchial hyper-responsiveness in these 12 patients. Group mean exercise time and Borg scores were not significantly different in these 12 patients when compared to the 25 patients in whom bronchial hyper-responsiveness was not found. We conclude that airway obstruction and bronchial hyper-responsiveness are not likely to be important determinants of reduced exercise capacity and breathlessness in chronic heart failure.

Evaluation of the THRESHOLD trainer for inspiratory muscle endurance training: comparison with the weighted plunger method

Inspiratory muscle training (IMT) has been shown to enhance exercise performance. The weighted plunger (WP) system of inspiratory threshold loading is the most commonly used method of IMT, but is expensive and cumbersome. We have evaluated a commercially available portable spring-loaded IMT device, the THRESHOLD trainer. The WP and THRESHOLD trainer devices were evaluated with their opening pressures set, in random order, at 10, 20, 30 and 40 cmH2O. Using an airpump, pressure at the valve inlet was recorded at the point at which the valve opened, and at airflow rates of 20, 40, 60, 80 and 100 L.min-1. Ten THRESHOLD trainers were then compared using the same opening pressures and airflow rates. Finally, 10 patients with stable chronic heart failure (CHF) inspired, in random order, through the WP and THRESHOLD trainer for 4 min each. The pressure-time product (PTP) was calculated for each 4 min period, to compare the work performed on inspiring through each device. The mean measured opening pressures for the WP set at 10, 20, 30 and 40 cmH2O, were 9.0, 19.3, 27.9 and 39.2 cmH2O, respectively, and there was little change over the range of flow tested. Corresponding values for the THRESHOLD trainer were 7.5, 16.9, 26.2 and 39.1 cmH2O, with the pressure being closer to the set pressure as flow increased to that seen in clinical practice. The 10 different trainers tested performed very similarly to one another. Work performed (as measured by PTP) on inspiring through the WP and THRESHOLD trainer was not significantly different. Although less accurate than the weighted plunger, the THRESHOLD trainer is an inexpensive device of consistent quality. In a clinical setting it would be a satisfactory option for inspiratory muscle training in most patients, but less so in patients with very low inspiratory flow rates.

Inspiratory muscle endurance in patients with chronic heart failure

OBJECTIVE

To assess the significance of changes in respiratory muscle endurance in relation to respiratory and limb muscle strength in patients with mild to moderate chronic heart failure using a threshold loading technique.

SUBJECTS

20 patients with chronic heart failure (17 male) aged 63.8 (SD 7.4) years and 10 healthy men aged 63.1 (5.6) years. Heart failure severity was New York Heart Association (NYHA) grade II (n = 11) and NYHA grade III/IV (n = 9).

METHODS

Respiratory muscle strength was measured from mouth pressures during maximum inspiratory effort (MIP) at functional residual capacity (FRC) and limb muscle strength was measured using a hand grip dynamometer. Inspiratory muscle endurance was measured using a threshold loading technique. The total endurance duration, the maximum threshold pressure achieved (P-Max), and the inspiratory load (% ratio of P-Max/MIP) were recorded in all subjects.

RESULTS

Inspiratory muscles were weaker in patients with heart failure than in the controls [MIP 53.6 (16.5) v 70.9 (20.2) cm H2O, P < 0.05]. Hand grip strength was similar in both subject groups [31.6 (SD) v 36.1 (15.9) dynes]. Total endurance duration was significantly reduced in the patient group [494 (223) v 996 (267) s, P < 0.01], as was the maximal threshold pressure achieved [P-Max 18.5 (6.4) v 30.7 (6.6) cm H2O, P < 0.01]. When expressed as a percentage of MIP, P-Max was also lower in the patients [35.2 (11.8) v 44.8 (11.4)%, P < 0.05]. There was no significant correlation between any measure of endurance and limb muscle strength.

CONCLUSIONS

Respiratory muscle endurance is reduced in patients with chronic heart failure. These changes probably reflect a generalised skeletal myopathy and provide further evidence of respiratory muscle dysfunction in patients with this disease. Respiratory muscle endurance needs now to be related to symptoms and the effects of treatment and respiratory muscle training should also be explored.

Effect of a physiological insulin infusion on the cardiovascular responses to a high fat meal: evidence supporting a role for insulin in modulating postprandial cardiovascular homoeostasis in man

1. While the haemodynamic adjustments occurring after meal ingestion and the different effects of meals of different composition on these changes are well established, the mechanisms underlying these changes are less clear. Insulin, which has been shown to be both a positive inotrope and to stimulate vasodilatation in the skeletal muscle vascular bed, may account for the different cardiac and regional haemodynamic responses to high fat and high carbohydrate meals. 2. This study assessed the effect of an insulin infusion reproducing the plasma insulin profile seen after a high carbohydrate meal on the cardiovascular and regional haemodynamic response to a high fat meal. All measurements were carried out non-invasively in nine healthy lean subjects (mean age 24.5 +/- 1.3 years). 3. The high fat meal resulted in increases in cardiac output (0.7 +/- 0.32 l/min, P < 0.001), heart rate (7.8 +/- 2.1 beats/min, P < 0.001) and insulin (25.1 +/- 4.2 m-units/l, P < 0.001), and a decline in systemic vascular resistance (-1.9 +/- 0.9 units, P < 0.05) and superior mesenteric artery vascular resistance (-45 +/- 9 units, P < 0.01). After the high fat meal alone, calf vascular resistance and blood pressure did not change. After the high fat meal accompanied by insulin (peak insulin 86.1 +/- 10.1 m-units/l) there were greater cardiac responses [(P < 0.001); cardiac output, 1.17 +/- 0.36 l/min, and heart rate, 13.4 +/- 2.1 beats/min], and a larger fall in systemic vascular resistance and superior mesenteric artery vascular resistance. Unlike the high fat meal alone, the high fat meal with insulin was accompanied by a fall in calf vascular resistance (8.3 +/- 3.3 units) and blood pressure (3.8 +/- 1.6 mmHg). 4. The results of this study support a role for insulin in modulating postprandial cardiovascular homoeostasis; in particular, by its depressor action on skeletal muscle vasculature, insulin may in part contribute to the fall in blood pressure seen in the elderly, who have an inadequate cardiac response to the fall in systemic vascular resistance occurring after meal ingestion.

Mode of death in chronic heart failure. A request and proposition for more accurate classification

The proportion of patients reported to die suddenly or from progressive circulatory failure is not consistent among studies of heart failure. Lack of an adequate or consistent classification of how patients die contributes to the current confusion over the mode of death in heart failure. Defining how patients with heart failure die could be important in developing strategies to reduce the continuing high mortality associated with this condition. We identified 27 studies that reported 50 or more deaths among patients with heart failure to ascertain how death was classified. Definitions of sudden death appeared heterogeneous and the majority of studies failed to publish or make reference to how circulatory failure was defined. A framework for the classification of the mode of death has been developed in which clear separation of the activity and place at the time of death, cause of death, mode of death, and events prior to death is made (ACME: Activity, Cause, Mode and Event). This mode of classifying death has been successfully piloted in two mortality studies; AIRE and NETWORK. Classifying mortality in this way will help identify pathways leading to death and hence suggest therapies and strategies to reduce mortality in patients with heart failure, a group of patients whose prognosis remains poor.

Central and peripheral haemodynamic responses to high carbohydrate and high fat meals in human cardiac transplant recipients

1. Patients with autonomic dysfunction and elderly people with an age-related decline in autonomic function can suffer from a fall in blood pressure after eating. While the cardiovascular changes after eating and the effect of meal composition on these changes are well established, the underlying mechanisms are less clear. 2. This study assessed the cardiac, circulatory and humoral responses to ingestion of isoenergetic (2.5 MJ) high carbohydrate and high fat meals in nine orthotopic cardiac transplant recipients, who before transplantation had significant circulatory, metabolic and autonomic abnormalities and after transplantation had complete or partial extrinsic cardiac denervation, and compared them to the responses seen in nine healthy age-matched control subjects. 3. All variables were measured non-invasively. Cardiac transplant recipients, despite cardiac denervation, showed a normal heart rate response to high carbohydrate and high fat meals (maximal increase at 30 min postprandially + 7.8 +/- 1.1 and + 63 +/- 1.4 beats/min respectively), a normal cardiac output response to the high carbohydrate meal (maximal increase at 30 min + 1.16 +/- 0.25 l/min), but a significantly attenuated cardiac output response to the high fat meal. Cardiac transplant recipients had attenuated superior mesenteric artery blood flow responses after both meals (P < 0.05) and an attenuated calf vascular resistance response after the high fat meal (P < 0.01). Throughout the study after both meals, cardiac transplant recipients maintained blood pressure. 4. This study demonstrates that cardiac transplant recipients, despite partial or complete cardiac denervation, have a normal chronotropic response to food and a normal cardiac output response to a high carbohydrate meal. The attenuated cardiac output response to a high fat meal did not compromise blood pressure, due at least in part to decreased splanchnic vasodilatation.

The importance of abnormalities of liver function tests in predicting mortality in chronic heart failure

A number of simple clinical and laboratory variables were analysed in a group of patients with chronic heart failure to evaluate their prognostic significance. Five hundred and fifty-two patients were followed for a maximum of 13 years with a total exposure time to death or censored survival of 1148 years. Of the clinical variables, diuretic dose and NYHA class were related to mortality (P < 0.01), and ischaemic heart disease was associated with a worse prognosis than other aetiologies (P < 0.05). Of the laboratory variables, abnormalities of liver function tests including bilirubin (P < 0.01), aspartate transaminase (P < 0.005), gamma glutamyl transpeptidase (P < 0.005) and alkaline phosphatase (P < 0.01) were all related to mortality as was plasma urate (P < 0.01). Multivariate survival analysis of all variables showed aspartate transaminase (chi 2 17.36, P < 0.001) accounted for the greatest variance followed by serum bilirubin (chi 2 14.35, P < 0.005). Thus, abnormalities in liver function tests have prognostic importance in chronic heart failure.

Failure of "effective" treatment for heart failure to improve normal customary activity

OBJECTIVES

To examine the effects of drug treatment on laboratory exercise tests in relation to measures of daily activity in patients with chronic heart failure.

SETTING

University teaching hospital.

SUBJECTS

18 patients with mild to moderate chronic heart failure (New York Heart Association functional class II-III) and 10 age matched healthy controls.

METHODS

Assessments were made before and after 12 weeks of vasodilator drug treatment. Exercise capacity was measured during two different types of treadmill exercise, one using a ramp protocol and the other a fixed work load. Corridor walk tests at three self selected speeds were also undertaken and measures of customary activity assessed from pedometer scores.

RESULTS

Exercise times were significantly increased from baseline (P < 0.01) with both treadmill protocols after 12 weeks of drug treatment, with a positive correlation between the duration of treadmill exercise for both protocols (r = 0.69, P < 0.01). Corridor walk tests of 100 m at a self selected slow speed also improved (P < 0.02) but these did not correlate with the changes in treadmill exercise time. The pedometer scores of the patients with heart failure were greatly reduced compared with those of the controls (258 (45) x 10(2) v 619 (67) x 10(2) steps/week, P < 0.001) and after 12 weeks of treatment were unchanged (261 (42) x 10(2) steps/week).

CONCLUSIONS

These data confirm the need to use different exercise protocols when assessing the benefits of drug treatment in patients with chronic heart failure. Treatments that seem effective with conventional laboratory based exercise tests may not improve daily activities. This may reflect a failure of apparently successful treatment and should be considered when interpreting clinical trials.

Respiratory muscle strength in chronic heart failure

BACKGROUND

Several studies have suggested that the respiratory muscles are weak in patients with heart failure, but the aetiology and clinical relevance of this weakness are unclear. In order to see if respiratory muscle weakness in this context is part of a more generalised myopathic process, respiratory and limb muscle strength were compared in patients with heart failure. The relation between respiratory muscle strength, breathlessness on exercise, and exercise capacity was also examined.

METHODS

Twenty patients (three women) with New York Heart Association (NYHA) class II-IV heart failure of mean age 63 years were studied. Respiratory muscle strength was assessed using maximum inspiratory and expiratory mouth pressures (MIP and MEP) and transdiaphragmatic pressure during sniffs (sniff PDI). These parameters were compared with cardiac output (indirect Fick) and with limb muscle strength as assessed by grip strength. The patients also performed two exercise tests during which they rated their breathlessness on a Borg scale.

RESULTS

Mean (SD) cardiac index was 2.2 (0.4) l/min/m2. MIP and MEP were 66 (27) and 99 (29) cm H2O respectively. Sniff PDI was 103 (21) cm H2O and was positively correlated with grip strength and cardiac output (Spearman rank correlation coefficients 0.527 and 0.451, respectively). None of the indices of respiratory muscle strength were related to exercise time or breathlessness during exercise.

CONCLUSIONS

The respiratory muscles are weak in patients with heart failure. This weakness reflects a more generalised myopathic process, possibly related to reduced cardiac output. However, respiratory muscle weakness does not appear to be an important factor in the aetiology of breathlessness on exercise.

ACE for whom? Implications for clinical practice of post-infarct trials

OBJECTIVE

To determine how many lives would be saved if patients were routinely treated with ACE inhibitors after myocardial infarction according to the criteria of four recent major clinical trials, and to estimate the costs and benefits of these approaches.

DESIGN

Retrospective survey.

SETTING

The Nottingham Health District.

PATIENTS

Data from 7855 patients admitted between 1989 and 1990 were combined and the selection criteria of four major clinical trials (AIRE, SAVE, GISSI-3, and ISIS-4) were applied.

RESULTS

Of the patients admitted in Nottingham with confirmed myocardial infarcts 39% were eligible for AIRE and 8% for SAVE. In patients with suspected myocardial infarction as defined by the major trials, 60% would have been eligible for GISSI-3 and 63% for ISIS-4. Treating appropriate patients in accordance with these trials would have saved 20 (AIRE), 3 (SAVE), 4 (GISSI-3) and 5 (ISIS-4) lives each year in Nottingham at a drug cost of 5400 pounds, 33 pounds 791, 2730 pounds, and 4116 pounds per life per year saved respectively.

CONCLUSIONS

Short-term treatment with ACE inhibition appears to be cheaper but such an approach would save fewer lives. The AIRE study is the most applicable to current clinical practice but ACE inhibitors should be offered routinely to patients satisfying the criteria of any of the four major clinical trials.

Static lung compliance in chronic heart failure: relation with dyspnoea and exercise capacity

BACKGROUND

The pathogenesis of dyspnoea in patients with chronic heart failure is poorly understood. Static lung compliance is reduced in chronic heart failure. The relation between static lung compliance and exercise capacity and dyspnoea in chronic heart failure has been investigated.

METHODS

Static lung compliance was calculated from expiratory pressure-volume curves in 18 patients with chronic heart failure (three women, mean age 62 years). Catheter mounted pressure transducers were used to measure changes in oesophageal pressure. Changes in lung volume were determined by integrating flow at the mouth, measured by a pneumotachograph. New York Heart Association (NYHA) class for dyspnoea was determined by a single observer. Patients underwent treadmill exercise to symptom limited maximum using staged and fixed rate protocols. Borg ratings for dyspnoea at submaximal exercise were measured.

RESULTS

Static lung compliance, whether expressed as % total lung capacity (TLC)/cm H2O or % predicted TLC/cm H2O, was unrelated to NYHA class. Similarly, there was no relation between static lung compliance and exercise capacity with either protocol or with Borg ratings for dyspnoea at submaximal exercise, with the exception of that measured after 11 minutes of the staged protocol.

CONCLUSIONS

Static lung compliance at rest has no relation with treadmill exercise capacity in chronic heart failure, and its relation with measures of dyspnoea is variable. No role for lung elasticity in determining the symptomatology of chronic heart failure was found.

Effects of captopril and oxygen on sleep apnoea in patients with mild to moderate congestive cardiac failure

OBJECTIVES

To determine the effects of captopril and oxygen on sleep quality in patients with mild to moderate cardiac failure.

DESIGN

An open observational study.

PATIENTS

12 patients with New York Heart Association class II-III heart failure were studied at baseline. 9 of these patients were then examined at the end of 1 month of treatment with captopril; 9 of the patients were separately assessed during a single night of supplementary oxygen.

MAIN OUTCOME MEASURES

Sleep patterns by polysomnography, overnight oximetry, and subjective sleep assessment using visual analogue scores.

RESULTS

Abnormal sleep was present in all baseline studies. Complete polysomnograms after treatment with captopril were obtained in 8 patients. Light sleep (stages 1 and 2) was reduced (mean (SEM) 61%(8)% to 48%(6)% actual sleep time, P < 0.05) but slow wave (stages 3 and 4) and REM (rapid eye movement) sleep increased (25%(6)% to 31%(5)%, 14%(2)% to 21%(5)% actual sleep time, P < 0.05). Apnoeic episodes (242(59) to 118(30), P < 0.05), desaturation events (171(60) to 73(37), P < 0.05), and arousals (33(5) to 18(3) P < 0.01) were reduced. Visual analogue scores of sleep quality increased 49(5) to 69(5), P < 0.01). Complete polysomnograms were obtained in 7 patients treated with oxygen. Light sleep duration was reduced (55% (7)% to 42%(5)% actual sleep time, P < 0.05) and slow wave sleep increased (30%(5)% to 38%(6)% actual sleep time, P < 0.05). REM sleep duration was not significantly different. Total arousals (33(6)% to 20(2) P < 0.05), desaturation events (140(33) to 38(10), P < 0.01), and apnoeic episodes (212(53) to 157(33), P < 0.05) were reduced. Visual analogue scores of sleep quality were unchanged.

CONCLUSIONS

Captopril and oxygen may improve sleep quality and reduce nocturnal desaturation in patients with mild to moderate cardiac failure. Improved sleep quality could explain the reduction in daytime symptoms seen after treatment in patients with chronic heart failure.

Clinical and economic factors in the treatment of congestive heart failure

Congestive heart failure (CHF) is a disease of massive clinical and economic importance throughout the developed world. Approximately 1% of the population are affected, with incidence and prevalence of CHF increasing with age. The major aetiological factor is ischaemic heart disease and, despite advances in treatment, mortality from CHF remains appallingly high, and comparable to that of many malignancies. The majority of patients with CHF require treatment with a diuretic, though there is now clear evidence that the addition of an angiotensin converting enzyme (ACE) inhibitor will not only improve symptoms but also reduce mortality and delay the progression of the disease. The vast economic impact of CHF is now becoming fully appreciated, with the majority of expenditure on hospital admissions. The earlier and more widespread use of ACE inhibitors in the treatment of CHF would be highly cost effective, with substantial savings in hospitalisation costs, though new and effective treatments are still urgently required.

Haemodynamic and hormonal response to a stream of cooled air

Many patients with angina note that their symptoms deteriorate in cold weather, although the precise physiological mechanism that explains this remains unclear. Exposure of the face to cool winds may be a contributory factor. The cardiovascular and hormonal response to a localised stream of room (22 degrees C) and cold (4 degrees C) air during submaximal treadmill exercise was therefore studied in nine normal subjects. Cardiac output and respiratory gases were measured with a mass spectrometer, using the indirect Fick principle. Blood samples were taken for plasma noradrenaline. A localised stream of air at 5 m.s-1 produced significant cardiovascular effects at rest, some of which persisted during exercise. In response to cold air, stroke volume, cardiac output, blood pressure and oxygen uptake increased (all P < 0.05). There was a trend towards a reduction in heart rate at rest and increase in plasma noradrenaline. Room air caused a reduction in blood pressure (P = 0.01) but stroke volumes and oxygen uptake were unchanged. The results of this study demonstrate significant cardiovascular effects of a cooled air facial stimulus at rest and during exercise. They may, in part, explain the effects of cold winds on patients with angina.