Exercise testing and exercise stress echocardiography in asymptomatic aortic valve stenosis

Management of asymptomatic patients with severe aortic valve stenosis (AVS) remains a source of debate. Exercise testing is no longer contraindicated and needs now to be considered when evaluating asymptomatic patients with AVS. Several studies have clearly demonstrated that exercise-elicited symptoms during conventional upright exercise portends clinical events. Semi-supine exercise with continuous Doppler echocardiography monitoring elicits cardiovascular abnormalities that are not detected at rest. Abnormal left ventricular response to exercise and/or major increase in mean transvalvular gradient add to the prognostic value of elicited symptoms in asymptomatic patients with severe AVS. However, preliminary experience needs to be confirmed to warrant routine use of exercise Doppler echocardiography in the evaluation of patients with asymptomatic AVS.

Cardiac resynchronisation therapy reduces functional mitral regurgitation during dynamic exercise in patients with chronic heart failure: an acute echocardiographic study

OBJECTIVES

To assess non-invasively the acute effects of cardiac resynchronisation therapy (CRT) on functional mitral regurgitation (MR) at rest and during dynamic exercise.

METHODS

21 patients with left ventricular (LV) systolic dysfunction and functional MR at rest, treated with CRT, were studied. Each patient performed a symptom-limited maximal exercise with continuous two dimensional Doppler echocardiography twice. The first exercise was performed with CRT; the second exercise was performed without CRT. Mitral regurgitant flow volume (RV), effective regurgitant orifice area (ERO) and LV dP/dt were measured at rest and at peak exercise.

RESULTS

CRT mildly reduced resting mitral ERO (mean 8 (SEM 2) v 11 (2) mm(2) without CRT, p = 0.02) and RV (13 (3) v 18 (3) ml without CRT, p = 0.03). CRT attenuated the spontaneous increase in mitral ERO and RV during exercise (1 (1) v 9 (2) mm(2), p = 0.004 and 1 (1) v 8 (2) ml, p = 0.004, respectively). CRT also significantly increased exercise-induced changes in LV dP/dt (140 (46) v 479 (112) mm Hg/s, p < 0.001).

CONCLUSION

Attenuation of functional MR, induced by an increase in LV contractility during dynamic exercise, may contribute to the beneficial clinical outcome of CRT in patients with chronic heart failure and LV asynchrony.

[Functional mitral insufficiency: a neglected vascular lesion?]

Functional mitral regurgitation is usually neglected during the course of dilated cardiomyopathies. However, functional mitral regurgitation is a sensitive marker of decreased survival. Recent development of treatments such as new surgical approach, permanent biventricular pacing and beta-blockade therapy lead to assess and treat more specifically the accompanying functional mitral regurgitation in congestive heart failure.

Physical training in patients with chronic heart failure enhances the expression of genes encoding antioxidative enzymes

OBJECTIVES

We sought to determine whether the benefit of training for vasodilation in the skeletal muscle vasculature of patients with chronic heart failure (CHF) is likely to be caused at the molecular level primarily by increased nitric oxide (NO) production or decreased inactivation of NO.

BACKGROUND

Physical training reverses endothelium dysfunction in patients with CHF, mediated by increased NO bioactivity. Some animal studies support a mechanism whereby training results in increased vascular NO levels by sustained transcriptional activation of the endothelial NO synthase (eNOS) gene, presumably due to shear stress. The mechanism has not been addressed in patients with CHF.

METHODS

The steady state transcript levels for eNOS and two other shear stress regulated genes (angiotensin-converting enzyme [ACE] and prostacyclin synthase [PGI2S]) were measured in samples of skeletal muscle from patients with CHF before and after 12 weeks of training. Transcript levels were measured in the same samples for two genes encoding antioxidant enzymes, copper zinc superoxide dismutase (Cu/Zn SOD) and glutathione peroxidase (GSH-Px). Untrained patients served as controls.

RESULTS

As expected, training significantly enhanced peak oxygen uptake in the patients with CHF. Training did not increase steady-state transcript levels for eNOS, ACE or PGI2S. In striking contrast, training increased the expression of the antioxidative enzyme genes by approximately 100%.

CONCLUSIONS

Our results do not support a model of benefit from training by increased eNOS expression. However, the data are entirely consistent with the alternative hypothesis, that reduced oxidative stress may account for the increase in vascular NO-mediated vasodilation. Insight into the mechanism may be relevant when considering therapies for exercise-intolerant patients with CHF.

Mitral ring annuloplasty: an incomplete correction of functional mitral regurgitation associated with left ventricular remodeling

Functional mitral regurgitation (FMR) occurs commonly in patients undergoing left ventricular (LV) remodeling. It is ubiquitous in patients referred to cardiac transplantation for LV systolic dysfunction and predicts a poor prognosis. The LV remodeling that is responsible for FMR is well understood and involves regional LV dysfunction Mitral annular dilatation is present in patients with idiopathic dilated cardiomyopathy but most often absent in patients with ischemic cardiomyopathy. Nonrandomized observations indicate that implantation of a mitral undersized flexible mitral ring reduces the amount of FMR, reverses LV remodeling, and improves symptoms in patients with end-stage cardiomyopathy and severe FMR. Whether a surgical procedure that does not correct the major LV alterations leading to FMR can have long-lasting effects on the amount of FMR and the reversal of LV remodeling remains to be demonstrated in randomized trials.

One-year survival following early revascularization for cardiogenic shock

CONTEXT

Cardiogenic shock (CS) is the leading cause of death for patients hospitalized with acute myocardial infarction (AMI).

OBJECTIVE

To assess the effect of early revascularization (ERV) on 1-year survival for patients with AMI complicated by CS.

DESIGN

The SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) Trial, an unblinded, randomized controlled trial from April 1993 through November 1998.

SETTING

Thirty-six referral centers with angioplasty and cardiac surgery facilities.

PATIENTS

Three hundred two patients with AMI and CS due to predominant left ventricular failure who met specified clinical and hemodynamic criteria.

INTERVENTIONS

Patients were randomly assigned to an initial medical stabilization (IMS; n = 150) group, which included thrombolysis (63% of patients), intra-aortic balloon counterpulsation (86%), and subsequent revascularization (25%), or to an ERV group (n = 152), which mandated revascularization within 6 hours of randomization and included angioplasty (55%) and coronary artery bypass graft surgery (38%).

MAIN OUTCOME MEASURES

All-cause mortality and functional status at 1 year, compared between the ERV and IMS groups.

RESULTS

One-year survival was 46.7% for patients in the ERV group compared with 33.6% in the IMS group (absolute difference in survival, 13.2%; 95% confidence interval [CI], 2.2%-24.1%; P<.03; relative risk for death, 0.72; 95% CI, 0.54-0.95). Of the 10 prespecified subgroup analyses, only age (<75 vs >/= 75 years) interacted significantly (P<.03) with treatment in that treatment benefit was apparent only for patients younger than 75 years (51.6% survival in ERV group vs 33.3% in IMS group). Eighty-three percent of 1-year survivors (85% of ERV group and 80% of IMS group) were in New York Heart Association class I or II.

CONCLUSIONS

For patients with AMI complicated by CS, ERV resulted in improved 1-year survival. We recommend rapid transfer of patients with AMI complicated by CS, particularly those younger than 75 years, to medical centers capable of providing early angiography and revascularization procedures.

Effect of very early angiotensin-converting enzyme inhibition on left ventricular dilation after myocardial infarction in patients receiving thrombolysis: results of a meta-analysis of 845 patients. FAMIS, CAPTIN and CATS Investigators

OBJECTIVES

We sought to investigate the effect of angiotensin-converting enzyme (ACE) inhibition <9 h after myocardial infarction (MI) on left ventricular (LV) dilation in patients receiving thrombolysis.

BACKGROUND

The ACE inhibitors reduce mortality after MI. Attenuation of LV dilation has been suggested as an important mechanism.

METHODS

The data of 845 patients with three-month echocardiographic follow-up after MI were combined from three randomized, double-blind, placebo-controlled studies. The criteria for these studies included: 1) thrombolytic therapy; 2) ACE inhibition within 6 to 9 h; and 3) evaluation of LV dilation as the primary objective.

RESULTS

The ACE inhibitor was started 3.2+/-1.7 h after the patients' first (mainly, 85%) anterior MI. After three months, LV dilation was not significantly attenuated by very early treatment with an ACE inhibitor. The diastolic volume index was attenuated by 0.5 ml/m2 (95% confidence interval [CI] -1.5 to 2.5, p = 0.61), and the systolic volume index by 0.5 ml/m2 (95% CI -1.0 to 1.9, p = 0.50). Subgroup analysis demonstrated that LV dilation was significantly attenuated by ACE inhibitor treatment for patients in whom reperfusion failed. In contrast, LV dilation was almost unaffected by ACE inhibitor treatment in successfully reperfused patients.

CONCLUSIONS

We could not demonstrate attenuation of LV dilation in patients receiving thrombolysis by ACE inhibitor treatment within 6 to 9 h after MI. We speculate that very early treatment with an ACE inhibitor has a beneficial effect on LV remodeling only in patients in whom reperfusion failed. Other mechanisms may be responsible for the beneficial effects of ACE inhibitors in successfully reperfused patients after MI.

Acute hemodynamic and clinical effects of levosimendan in patients with severe heart failure. Study Investigators

BACKGROUND

We determined the short-term hemodynamic and clinical effects of levosimendan, a novel calcium-sensitizing agent, in patients with decompensated heart failure.

METHODS AND RESULTS

One hundred forty-six patients with New York Heart Association functional class III or IV heart failure (mean left ventricular ejection fraction 21+/-1%) who had a pulmonary capillary wedge pressure >/=15 mm Hg and a cardiac index </=2.5 L x min(-1) x m(-2) were enrolled in a multicenter, double-blind, placebo-controlled study and randomized 2:1 to intravenous infusion of levosimendan or placebo. Drug infusions were uptitrated over 4 hours from an initial infusion rate of 0.1 microg x kg(-1) x min(-1) to a maximum rate of 0.4 microg x kg(-1) x min(-1) and maintained at the maximal tolerated infusion rate for an additional 2 hours. Levosimendan caused dose-dependent increases in stroke volume and cardiac index beginning with the lowest infusion rate and achieving maximal increases in stroke volume and cardiac index of 28% and 39%, respectively. Heart rate increased modestly (8%) at the maximal infusion rate and was not increased at the 2 lowest infusion rates. Levosimendan caused dose-dependent decreases in pulmonary capillary wedge, right atrial, pulmonary arterial, and mean arterial pressures. Levosimendan appeared to improve dyspnea and fatigue, as assessed by the patient and physician, and was not associated with a significant increase in adverse events.

CONCLUSIONS

Levosimendan caused rapid dose-dependent improvement in hemodynamic function in patients with decompensated heart failure. These hemodynamic effects appeared to be accompanied by symptom improvement and were not associated with a significant increase in the number of adverse events. Levosimendan may be of value in the short-term management of patients with decompensated heart failure.

Angiotensin II receptor subtypes in the skeletal muscle vasculature of patients with severe congestive heart failure

BACKGROUND

Vascular remodeling occurs in the skeletal muscle of patients with severe congestive heart failure (CHF); this remodeling is mediated in part by increased activity of the renin-angiotensin system. Animal models suggest that in the vasculature, angiotensin II receptor type 2 (AT2-R) expression may be upregulated in pathological states associated with vascular remodeling. The therapeutic effects of an AT1-R antagonist may, therefore, be in part due to increased plasma angiotensin II levels, which stimulate AT2-R. However, whether AT2-R is expressed in the skeletal muscle vasculature of patients with severe CHF is unknown.

METHODS AND RESULTS

The steady-state transcript levels of the AT1-R and AT2-R genes were analyzed by reverse transcription-polymerase chain reaction in RNA samples prepared from the skeletal muscle of 12 patients with severe CHF (f1.gif" BORDER="0">O(2)<10 mL. kg(-1). min(-1)) and 5 age-matched healthy subjects who underwent vastus lateralis biopsies. Human fetal skeletal muscle RNA served as a positive control for the expression of AT1-R and AT2-R gene transcripts. Transcripts from the AT1-R gene were detected readily in all samples. In contrast, transcripts from the AT2-R gene were only detected in fetal skeletal muscle samples and could not be detected in the skeletal muscle vasculature of healthy subjects or that of CHF patients, who were treated with either angiotensin-converting enzyme inhibitors or AT1-R antagonists.

CONCLUSIONS

The AT2-R gene is not expressed in the skeletal muscle of patients with CHF. In the absence of detectable AT2-R gene transcripts, the AT2-R pathway is unlikely to contribute to the effects of AT1-R antagonists on the skeletal muscle vasculature in patients with severe CHF.

Low-dose enoximone improves exercise capacity in chronic heart failure. Enoximone Study Group

OBJECTIVES

This study was designed to evaluate the effects of low-dose enoximone on exercise capacity.

BACKGROUND

At higher doses the phosphodiesterase inhibitor, enoximone, has been shown to increase exercise capacity and decrease symptoms in heart failure patients but also to increase mortality. The effects of lower doses of enoximone on exercise capacity and adverse events have not been evaluated.

METHODS

This is a prospective, double-blind, placebo-controlled, multicenter trial (nine U.S. centers) conducted in 105 patients with New York Heart Association class II to III, ischemic or nonischemic chronic heart failure (CHF). Patients were randomized to placebo or enoximone at 25 or 50 mg orally three times a day. Treadmill maximal exercise testing was done at baseline and after 4, 8 and 12 weeks of treatment, using a modified Naughton protocol. Patients were also evaluated for changes in quality of life and for increased arrhythmias by Holter monitoring.

RESULTS

By the protocol-specified method of statistical analysis (the last observation carried-forward method), enoximone at 50 mg three times a day improved exercise capacity by 117 s at 12 weeks (p = 0.003). Enoximone at 25 mg three times a day also improved exercise capacity at 12 weeks by 115 s (p = 0.013). No increases in ventricular arrhythmias were noted. There were four deaths in the placebo group and 2 and 0 deaths in the enoximone 25 mg three times a day and enoximone 50 mg three times a day groups, respectively. Effects on degree of dyspnea and patient and physician assessments of clinical status favored the enoximone groups.

CONCLUSIONS

Twelve weeks of treatment with low-dose enoximone improves exercise capacity in patients with CHF, without increasing adverse events.

Intravenous nesiritide, a natriuretic peptide, in the treatment of decompensated congestive heart failure. Nesiritide Study Group

BACKGROUND

Intravenous infusion of nesiritide, a brain (B-type) natriuretic peptide, has beneficial hemodynamic effects in patients with decompensated congestive heart failure. We investigated the clinical use of nesiritide in such patients.

METHODS

Patients hospitalized because of symptomatic congestive heart failure were enrolled in either an efficacy trial or a comparative trial. In the efficacy trial, which required the placement of a Swan-Ganz catheter, 127 patients with a pulmonary-capillary wedge pressure of 18 mm Hg or higher and a cardiac index of 2.7 liters per minute per square meter of body-surface area or less were randomly assigned to double-blind treatment with placebo or nesiritide (infused at a rate of 0.015 or 0.030 microg per kilogram of body weight per minute) for six hours. In the comparative trial, which did not require hemodynamic monitoring, 305 patients were randomly assigned to open-label therapy with standard agents or nesiritide for up to seven days.

RESULTS

In the efficacy trial, at six hours, nesiritide infusion at rates of 0.015 and 0.030 microg per kilogram per minute decreased pulmonary-capillary wedge pressure by 6.0 and 9.6 mm Hg, respectively (as compared with an increase of 2.0 mm Hg with placebo, P<0.001), resulted in improvements in global clinical status in 60 percent and 67 percent of the patients (as compared with 14 percent of those receiving placebo, P<0.001), reduced dyspnea in 57 percent and 53 percent of the patients (as compared with 12 percent of those receiving placebo, P<0.001), and reduced fatigue in 32 percent and 38 percent of the patients (as compared with 5 percent of those receiving placebo, P<0.001). In the comparative trial, the improvements in global clinical status, dyspnea, and fatigue were sustained with nesiritide therapy for up to seven days and were similar to those observed with standard intravenous therapy for heart failure. The most common side effect was dose-related hypotension, which was usually asymptomatic.

CONCLUSIONS

In patients hospitalized with decompensated congestive heart failure, nesiritide improves hemodynamic function and clinical status. Nesiritide is useful for the treatment of decompensated congestive heart failure.

Acute endothelin A receptor blockade causes selective pulmonary vasodilation in patients with chronic heart failure

BACKGROUND

Elevated plasma endothelin-1 (ET-1) levels in patients with chronic heart failure correlate with pulmonary artery pressures and pulmonary vascular resistance. ET(A) receptors on vascular smooth muscle cells mediate pulmonary vascular contraction and hypertrophy. We determined the acute hemodynamic effects of sitaxsentan, a selective ET(A) receptor antagonist, in patients with chronic stable heart failure receiving conventional therapy.

METHODS AND RESULTS

This multicenter, double-blind, placebo-controlled trial enrolled 48 patients with chronic New York Heart Association functional class III or IV heart failure (mean left ventricular ejection fraction 21+/-1%) treated with ACE inhibitors and diuretics. Patients with a baseline pulmonary capillary wedge pressure >/=15 mm Hg and a cardiac index </=2.5 L. min(-1). m(-2) were randomized to 1 of 3 doses (1.5, 3.0, or 6.0 mg/kg) of sitaxsentan or placebo as an intravenous infusion over 15 minutes. Hemodynamic responses were assessed by catheterization of the right side of the heart for 6 hours. Sitaxsentan decreased pulmonary artery systolic pressure, pulmonary vascular resistance, mean pulmonary artery pressure, and right atrial pressure (P</=0.001, 0.003, 0.017, and 0.031, respectively) but had no effect on heart rate, mean arterial pressure, pulmonary capillary wedge pressure, cardiac index, or systemic vascular resistance. Plasma ET-1 levels were elevated at baseline and decreased with sitaxsentan.

CONCLUSIONS

In patients with moderate to severe heart failure receiving conventional therapy, acute ET(A) receptor blockade caused selective pulmonary vasodilation associated with a reduction in plasma ET-1. Sitaxsentan may be of value in the treatment of patients with pulmonary hypertension secondary to chronic heart failure.

Modulation of vascular endothelial gene expression by physical training in patients with chronic heart failure

BACKGROUND

Abnormalities of the skeletal muscle vasculature, such as endothelial dysfunction and reduced microvascular density, can be reversed by physical training in patients with chronic heart failure. The molecular mechanisms that mediate the beneficial effects of physical training on the vascular endothelium are unknown.

METHODS

Endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) gene expression in the skeletal muscle, peak oxygen consumption (VO2) and calf peak reactive hyperemia were measured before and after 12 weeks of supervised physical training in 10 patients with chronic heart failure. Five patients with heart failure of similar severity who did not participate in the training program served as controls.

RESULTS

The effects of physical training on eNOS and VEGF gene expression were heterogeneous. eNOS gene expression increased 3-4 fold in 4 patients while it remained constant in 6 patients. VEGF gene expression increased significantly in all patients who were not treated with beta-adrenergic blockade and remained constant in all patients who were treated with beta-adrenergic blockade. In contrast, physical training increased peak VO2 and calf peak reactive hyperemia in all patients. Mean peak VO2 increased from 13.13 +/- 2.21 to 16.19 +/- 2.69 ml/kg/min (p < 0.001) and calf peak reactive hyperemia increased from 19.7 +/- 2.3 to 29.6 +/- 4.0 ml*min(-1)*100 ml(-1) (p < 0.001).

CONCLUSIONS

A supervised program of physical training that consistently enhanced peak VO2 and vascular reactivity in patients with chronic heart failure increased or left eNOS and VEGF gene expression unchanged in skeletal muscle. Changes in vascular endothelial gene expression may contribute to the benefits of training on vascular endothelial function but are not solely responsible for these benefits.

Early revascularization in acute myocardial infarction complicated by cardiogenic shock. SHOCK Investigators. Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock

BACKGROUND

The leading cause of death in patients hospitalized for acute myocardial infarction is cardiogenic shock. We conducted a randomized trial to evaluate early revascularization in patients with cardiogenic shock.

METHODS

Patients with shock due to left ventricular failure complicating myocardial infarction were randomly assigned to emergency revascularization (152 patients) or initial medical stabilization (150 patients). Revascularization was accomplished by either coronary-artery bypass grafting or angioplasty. Intraaortic balloon counterpulsation was performed in 86 percent of the patients in both groups. The primary end point was mortality from all causes at 30 days. Six-month survival was a secondary end point.

RESULTS

The mean age of the patients was 66+/-10 years, 32 percent were women and 55 percent were transferred from other hospitals. The median time to the onset of shock was 5.6 hours after infarction, and most infarcts were anterior in location. Ninety-seven percent of the patients assigned to revascularization underwent early coronary angiography, and 87 percent underwent revascularization; only 2.7 percent of the patients assigned to medical therapy crossed over to early revascularization without clinical indication. Overall mortality at 30 days did not differ significantly between the revascularization and medical-therapy groups (46.7 percent and 56.0 percent, respectively; difference, -9.3 percent; 95 percent confidence interval for the difference, -20.5 to 1.9 percent; P=0.11). Six-month mortality was lower in the revascularization group than in the medical-therapy group (50.3 percent vs. 63.1 percent, P=0.027).

CONCLUSIONS

In patients with cardiogenic shock, emergency revascularization did not significantly reduce overall mortality at 30 days. However, after six months there was a significant survival benefit. Early revascularization should be strongly considered for patients with acute myocardial infarction complicated by cardiogenic shock.

Effect of aspirin and ifetroban on skeletal muscle blood flow in patients with congestive heart failure treated with Enalapril. Ifetroban Study Group

OBJECTIVES

The purpose of this study was to determine the acute and chronic effects of cyclooxygenase inhibition with aspirin and thromboxane A2 receptor blockade with ifetroban on the chronic vasodilating effects of enalapril in the skeletal muscle circulation of patients with heart failure.

BACKGROUND

Angiotensin-converting enzyme inhibition and antiplatelet therapy with aspirin independently reduce the risk for subsequent nonfatal coronary events in survivors of myocardial infarction. The safety of the combined administration of angiotensin-converting enzyme inhibitors and aspirin has been questioned due to their divergent effects on the vascular synthesis of vasodilating prostaglandins.

METHODS

Forearm blood flow (ml/min/100 ml) at rest and during rhythmic handgrip exercise and after transient arterial occlusion was determined by strain gauge plethysmography before and 4 h and six weeks after combined administration of enalapril with either aspirin, ifetroban or placebo in a multicenter, double-blind, randomized trial of 62 patients with mild to moderate heart failure.

RESULTS

Before randomization, forearm hemodynamics were similar in the three treatment groups except for increased resting forearm blood flow and decreased resting forearm vascular resistance in the aspirin group when compared with the placebo group. After combined administration of enalapril and study drug for 4 h and six weeks, changes from prerandomization values of mean arterial pressure, forearm blood flow and forearm vascular resistance at rest, during handgrip exercise and after transient arterial occlusion did not differ among the three treatment groups.

CONCLUSIONS

These findings demonstrate that the vasodilating effects of enalapril in the skeletal muscle circulation of patients with heart failure are not critically dependent on prostaglandin pathways.

Sustained hemodynamic effects of an infusion of nesiritide (human b-type natriuretic peptide) in heart failure: a randomized, double-blind, placebo-controlled clinical trial. Natrecor Study Group

OBJECTIVES

The goal of this study was to further define the role of nesiritide (human b-type natriuretic peptide) in the therapy of decompensated heart failure (HF) by assessing the hemodynamic effects of three doses (0.015, 0.03 and 0.06 microg/kg/min) administered by continuous intravenous (IV) infusion over 24 h as compared with placebo.

BACKGROUND

Previous studies have shown beneficial hemodynamic, neurohormonal and renal effects of bolus dose and 6-h infusion administration of nesiritide in HF patients. Longer term safety and efficacy have not been studied.

METHODS

This randomized, double-blind, placebo-controlled multicenter trial enrolled subjects with symptomatic HF and systolic dysfunction (left ventricular ejection fraction < or =35%). Central hemodynamics were assessed at baseline, during a 24-h IV infusion and for 4 h postinfusion.

RESULTS

One hundred three subjects with New York Heart Association class II (6%), III (61%) or IV (33%) HF were enrolled. Nesiritide produced significant reductions in pulmonary wedge pressure (27% to 39% decrease by 6 h), mean right atrial pressure and systemic vascular resistance, along with significant increases in cardiac index and stroke volume index, with no significant effect on heart rate. Beneficial effects were evident at 1 h and were sustained throughout the 24-h infusion.

CONCLUSIONS

The rapid and sustained beneficial hemodynamic effects of nesiritide observed in this study support its use as a first-line IV therapy for patients with symptomatic decompensated HF.

Sustained improvement in flow-mediated vasodilation after short-term administration of dobutamine in patients with severe congestive heart failure

BACKGROUND

In patients with severe congestive heart failure (CHF), short-term administration of dobutamine exerts sustained clinical benefits that are partially mediated by a training-like effect on skeletal muscle. Recently, physical training has been shown to enhance endothelial function in the skeletal muscle vasculature by improving endothelial function. Whether the dobutamine-induced training effect is also associated with an improvement in endothelial function in the skeletal muscle vasculature is currently unknown.

METHODS AND RESULTS

Flow-mediated vasodilation in response to peak reactive hyperemia was evaluated in the forearms of 9 patients with severe CHF who were treated with dobutamine for 72 hours. Resting and peak hyperemic brachial artery blood flow and diameter (BABF [mL/min] and BAD [mm], respectively) were measured by 2-dimensional and Doppler ultrasonography at baseline, at 3 and 72 hours during dobutamine infusion, and at 2 and 4 weeks after discontinuation of dobutamine therapy. In addition, the brachial artery response to sublingual (SL) administration of nitroglycerin (NTG) was evaluated at baseline and at 2 and 4 weeks after discontinuation of dobutamine therapy. Ten patients with severe CHF who did not receive dobutamine served as control subjects. Resting BABF was significantly increased at 3 and 72 hours (391.2+/-31.8 and 366.8+/-31.0 mL/min, respectively, compared with 289.8+/-18.6 mL/min at baseline; P<0.05). Peak hyperemic BABF was not altered by dobutamine infusion compared with baseline values. The increase in BAD during peak hyperemic response was greater after infusion of dobutamine for 72 hours (15.2+/-2.7% versus 9.1+/-1.8%, P<0.05) and remained significantly greater for >/=2 weeks after discontinuation of dobutamine (12.3+/-2.2% versus 9.1+/-1.8%, P<0.05). In contrast to the peak hyperemic response, the increase in BAD (%) induced by SL NTG was unchanged by administration of dobutamine for 72 hours. Two and 4 weeks after discontinuation of dobutamine, NTG-induced increases in BAD were similar to the BAD noted at baseline.

CONCLUSIONS

In patients with severe CHF, short-term administration of dobutamine for 72 hours selectively improves vascular endothelial function for >/=2 weeks.

Angiotensin II-receptor blockade further reduces afterload safely in patients maximally treated with angiotensin-converting enzyme inhibitors for heart failure

Combined therapy with an angiotensin-II type I receptor (AT1) antagonist and an angiotensin-converting enzyme (ACE) inhibitor results in more complete suppression of the renin-angiotensin system. Accordingly, the blood-pressure response and safety of combining AT1-receptor blockade with losartan for ACE inhibition were evaluated in patients with congestive heart failure who were already treated with maximally recommended or tolerated doses of an ACE inhibitor. Forty-three patients with symptomatic congestive heart failure were evaluated biweekly for 1 month before addition of losartan and weekly during administration of losartan at a daily dose of 25 mg for the first week and 50 mg for the second week. Systolic blood pressure, which remained unchanged before addition of losartan, decreased from 122 +/- 18 mm Hg to 112 +/- 17 and 107 +/- 17 mm Hg (p < 0.001) after 1 week of 25 mg and 1 week of 50 mg losartan, respectively. Diastolic blood pressure also significantly decreased. The decreases in blood pressure were well tolerated by all patients, even by those in whom symptomatic hypotension developed during uptitration of ACE inhibition. Serum potassium and sodium and parameters of renal function remained unchanged. Combining AT1-receptor blockade with losartan to maximally recommended or tolerated ACE inhibition appears safe and leads to further vasodilatation in symptomatic patients with congestive heart failure.

Training improves endothelium-dependent vasodilation in resistance vessels of patients with heart failure

The effects of physical training on endothelium-dependent vasodilation in skeletal muscle resistance vessels were investigated in patients with heart failure. Forearm blood flows (ml.min-1.100 ml-1) in response to brachial arterial administration of acetylcholine (5 x 10(-5) and 5 x 10(-4) M at 1 ml/min) and nitroglycerin (5 x 10(-6) and 5 x 10(-5) M at 1 ml/min) were determined by strain-gauge venous occlusion plethysmography before and after 8 wk of daily handgrip exercise in 12 patients with chronic heart failure. After 8 wk of daily handgrip exercise, the vasodilatory responses to acetylcholine significantly increased from pretraining values, i.e., 16.6 +/- 2.0 vs. 8.6 +/- 1.3 ml.min-1.100 ml-1 (P < 0.05) and 27.5 +/- 1.5 vs. 14.6 +/- 1.7 ml.min-1.100 ml-1 (P < 0.05), respectively, whereas the vasodilatory responses to nitroglycerin did not change. Handgrip exercise training appears to specifically enhance endothelium-dependent vasodilation in the forearm skeletal muscle circulation of patients with heart failure.

Nonselective beta-adrenergic blockade with carvedilol does not hinder the benefits of exercise training in patients with congestive heart failure

BACKGROUND

Long-term beta-adrenergic blockade does not appear to be associated with drug-induced training in patients with congestive heart failure (CHF); whether exercise training can increase peak aerobic capacity in patients with CHF who are treated with beta-adrenergic blockers is currently unknown.

METHODS AND RESULTS

We studied 23 patients with CHF who were treated with carvedilol or propranolol in addition to ACE inhibitors, furosemide, and digoxin. Of the patients treated with carvedilol, 8 underwent exercise training and 8 remained sedentary. All 7 patients treated with propranolol underwent exercise training. Peak oxygen consumption (mL.kg-1.min-1) was serially measured in trained and sedentary patients. Peak reactive hyperemia (mL.min-1.100 mL-1) was determined in the calf and forearm immediately before and after 12 weeks of training. The peak oxygen consumption of trained patients treated with either carvedilol or propranolol increased from 12.9 +/- 1.4 to 16.0 +/- 1.6 (P < .001) and 12.4 +/- 1.0 to 15.7 +/- 0.9 (P < .001) mL.kg-1.min-1, respectively, whereas it did not change in the sedentary patients. Peak reactive hyperemia increased significantly in the calves but not the forearms of trained patients.

CONCLUSIONS

Long-term, nonselective beta-adrenergic blockade with carvedilol or propranolol does not prevent patients with CHF from deriving systemic and regional benefits from physical training.

Exercise training in patients with severe congestive heart failure: enhancing peak aerobic capacity while minimizing the increase in ventricular wall stress

OBJECTIVES

The aims of the study were to 1) assess the effects of 12 weeks of exercise training at low work loads (i.e., corresponding to < or = 50% of peak oxygen consumption [Vo2]) on peak Vo2 and hyperemic calf blood flow in patients with severe congestive heart failure; and 2) evaluate left ventricular diastolic pressure and wall stress during exercise performed at work loads corresponding to < or = 50% and 70% to 80% of peak Vo2.

BACKGROUND

Whether the benefits of exercise training can be achieved at work loads that result in lower left ventricular diastolic wall stress than those associated with conventional work loads is unknown in patients with severe congestive heart failure.

METHODS

Sixteen patients with severe congestive heart failure trained at low work loads for 1 h/day, four times a week, for 12 weeks. Peak Vo2 and calf and forearm reactive hyperemia were measured before and during training. Nine of the 16 patients underwent right heart catheterization and echocardiography during bicycle exercise at low and conventional work loads (i.e., 50% and 70% to 80% of peak Vo2, respectively).

RESULTS

The increase in left ventricular diastolic wall stress was substantially lower during exercise at low work loads than during exercise at conventional work loads, (i.e., [mean +/- SEM] 23.3 +/- 7.4 vs. 69.6 +/- 8.1 dynes/cm2 (p < 0.001). After 6 and 12 weeks of training, peak Vo2 increased from 11.5 +/- 0.4 to 14.0 +/- 0.5 and 15.0 +/- 0.5 ml/kg per min, respectively (p < 0.0001 vs. baseline for both). Peak reactive hyperemia significantly increased in the calf but not in the forearm. The increases in peak Vo2 and calf peak reactive hyperemia correlated closely (r = 0.61, p < 0.02).

CONCLUSIONS

In patients with severe congestive heart failure, peak Vo2 is enhanced by exercise training at work loads that result in smaller increases in left ventricular diastolic wall stress than those observed at conventional work loads.

Double-blind, placebo-controlled study of the effects of carvedilol in patients with moderate to severe heart failure. The PRECISE Trial. Prospective Randomized Evaluation of Carvedilol on Symptoms and Exercise

BACKGROUND

Carvedilol has improved the symptomatic status of patients with moderate to severe heart failure in single-center studies, but its clinical effects have not been evaluated in large, multicenter trials.

METHODS AND RESULTS

We enrolled 278 patients with moderate to severe heart failure (6-minute walk distance, 150 to 450 m) and a left ventricular ejection fraction < or = 0.35 at 31 centers. After an open-label, run-in period, each patient was randomly assigned (double-blind) to either placebo (n = 145) or carvedilol (n = 133; target dose, 25 to 50 mg BID) for 6 months, while background therapy with digoxin, diuretics, and an ACE inhibitor remained constant. Compared with placebo, patients in the carvedilol group had a greater frequency of symptomatic improvement and lower risk of clinical deterioration, as evaluated by changes in the NYHA functional class (P = .014) or by a global assessment of progress judged either by the patient (P = .002) or by the physician (P < .001). In addition, treatment with carvedilol was associated with a significant increase in ejection fraction (P < .001) and a significant decrease in the combined risk of morbidity and mortality (P = .029). In contrast, carvedilol therapy had little effect on indirect measures of patient benefit, including changes in exercise tolerance or quality-of-life scores. The effects of the drug were similar in patients with ischemic heart disease or idiopathic dilated cardiomyopathy as the cause of heart failure.

CONCLUSIONS

These findings indicate that, in addition to its favorable effects on survival, carvedilol produces important clinical benefits in patients with moderate to severe heart failure treated with digoxin, diuretics, and an ACE inhibitor.

Direct and indirect assessment of skeletal muscle blood flow in patients with congestive heart failure

Techniques which are currently used to measure skeletal muscle blood flow (SMBF) in patients with congestive heart failure (CHF) are neither convenient nor accurate. They have led to discrepant results in patients with congestive heart failure and are, in part, responsible for the ongoing debate regarding the factors which limit the rise in body oxygen consumption during exercise in these patients. However, direct measurement of SMBF may not be needed during exercise in patients with severe CHF. Their skeletal muscles maximally extract oxygen. Consequently, increase in oxygen consumption by the skeletal muscles is only mediated by a concomitant increase in SMBF. In patients with severe CHF, peak body oxygen consumption attained during maximal exercise closely depends on the rise in SMBF, and thus provides an indirect measurement of SMBF.

Circulating levels of cytokines and their endogenous modulators in patients with mild to severe congestive heart failure due to coronary artery disease or hypertension

OBJECTIVES

This study sought to determine the circulating levels of cytokines and their respective endogenous modulators in patients with congestive heart failure of variable severity.

BACKGROUND

Activation of immune elements localized in the heart or periphery, or both, may promote release of cytokines in patients with congestive heart failure. Although an increased circulating level of tumor necrosis factor-alpha (TNF-alpha) and its soluble receptor type II (sTNF-RII) is well documented, less is known about other cytokines (i.e., interleukin-1-beta [IL-1-beta], interleukin-6 [IL-6] and interleukin-2 [IL-2] and their soluble receptor/receptor antagonists).

METHODS

Circulating levels of TNF-alpha and sTNF-RII, IL-1-beta, IL-1 receptor antagonist (IL-1-Ra), IL-6, IL-6 soluble receptor (IL-6-sR), IL-2 and IL-2 soluble receptor-alpha were measured using enzyme-linked immunosorbent assay kits (Quantikine, R&D Systems) in 80 patients with congestive heart failure due to coronary artery disease or hypertension. The severity of their symptoms, which ranged from New York Heart Association functional class I to IV, was confirmed by measurement of peak oxygen consumption.

RESULTS

The percentage of patients with elevated levels of cytokines and their corresponding soluble receptor/receptor antagonists significantly increased with functional class. For TNF-alpha and IL-1-beta, the percentage of patients with elevated levels of soluble receptor/receptor antagonists was higher than that of patients with elevated levels of the cytokine itself. For IL-6, the percentage of patients with elevated levels of IL-6-sR tended to be lower than that of patients with elevated levels of IL-6. All but two patients had undetectable levels of IL-2, and all but seven had levels of IL-2-sR within a normal range.

CONCLUSIONS

In patients with congestive heart failure, circulating levels of cytokines increased with the severity of symptoms. In these patients, circulating levels of sTNF-RII and IL-1-Ra are more sensitive markers of immune activation than are circulating levels of TNF-alpha and IL-1-beta, respectively. Levels of IL-2 and IL-2-sR are not elevated when congestive heart failure is due to coronary artery disease or hypertension.

Quality of life in older patients with congestive heart failure. Effects of ACE inhibitors

Prolonged angiotensin converting enzyme (ACE) inhibition has been consistently demonstrated to increase life expectancy in symptomatic patients with congestive heart failure (CHF), and decrease morbidity in asymptomatic patients with left ventricular (LV) systolic dysfunction. However, prolonged ACE inhibition has not been shown to consistently improve the quality of life of patients with symptomatic CHF. The failure of ACE inhibition to improve quality of life cannot be readily explained, but several factors may contribute to this apparent lack of effect. First, endpoints such as death or hospitalisation are clearly easier to quantify and monitor than a patient's perception of how much CHF affects his/her life. Secondly, while ACE inhibition delays the progression of LV systolic dysfunction, which is the primary determinant of prognosis, it may not reverse the alterations in skeletal muscle vasculature, metabolism and mass, which are primarily responsible for exercise intolerance in patients with CHF. Lastly, patients with CHF, and particularly older patients, are also often incapacitated by other disease processes such as arthritis, loss of balance, pulmonary disorders and anaemia, which, to a large extent, affect the quality of their life more than LV systolic dysfunction and/or CHF.

Determination of vascular impedance in the peripheral circulation by transcutaneous pulsed Doppler ultrasound

Instantaneous blood flow velocity characteristics and vascular impedance spectra derived noninvasively by pulsed Doppler ultrasound and invasively by electromagnetic flow probe were compared in the canine common femoral artery to validate the pulsed Doppler technique for determination of vascular impedance in the peripheral circulation. Although Doppler ultrasonography is routinely performed to evaluate blood flow velocity patterns in the human peripheral circulation; the validity of this technique to derive peripheral vascular impedance has yet to be investigated. Simultaneous measurements of blood flow velocity were determined by both noninvasive pulsed Doppler ultrasound and surgically implanted electromagnetic flow probe in the common femoral artery of eight dogs and compared in both time and frequency domains. Vascular impedance spectra derived from measurements of blood flow velocity determined by Doppler ultrasound and electromagnetic flow probe and simultaneous measurement of arterial pressure by a micromanometer-tipped catheter were obtained at baseline and after intra-arterial injection of acetylcholine in five additional dogs. During the first 10 to 20% of the cardiac cycle, Doppler ultrasound blood flow velocity was transiently greater than the simultaneously recorded electromagnetic blood flow velocity. During the remainder of the cardiac cycle, the two blood flow velocity waveforms were nearly superimposable. The frequency spectra of the blood flow velocity waveforms derived from Doppler ultrasound and electromagnetic flow probes were similar for harmonies less than 10 Hz. Vascular impedance spectra derived from measurements of blood flow velocity determined by Doppler ultrasound and electromagnetic flow probe with simultaneous measurement of arterial pressure by a micromanometer-tipped catheter were similar at baseline and after regional administration of acetylcholine. Mean vascular resistance (impedance at 0 Hz), characteristic impedance, and the first minima of the impedance modulus derived from Doppler ultrasound and electromagnetic flow probe blood flow velocity measurements were closely correlated at baseline and after dilation with acetylcholine (r > or = 0.89, p < 0.05 for all correlations). Doppler ultrasonography is a convenient and accurate technique for determination of vascular impedance in the peripheral circulation.

Indications for immediate angiotensin-converting enzyme inhibition in patients with acute myocardial infarction

When initiated a few days after myocardial infarction, angiotensin-converting enzyme inhibition exerts beneficial effects on survival and morbidity in patients with asymptomatic left ventricular systolic dysfunction or symptomatic heart failure. During the acute phase of a myocardial infarction, angiotensin-converting enzyme inhibition appears to be well tolerated, to prevent the development of heart failure in patients with asymptomatic left ventricular systolic dysfunction and to improve the hemodynamic and clinical variables of heart failure when present. Accordingly, early angiotensin-converting enzyme inhibition is clearly indicated in patients with acute myocardial infarction associated with asymptomatic left ventricular dysfunction or clinical evidence of heart failure. Angiotensin-converting enzyme inhibition may also be beneficial when thrombolytic agents fail to restore coronary patency in patients with acute myocardial infarction.

Reduced peak aerobic capacity in asymptomatic left ventricular systolic dysfunction. A substudy of the studies of left ventricular dysfunction (SOLVD). SOLVD Investigator. Studies of Left Ventricular Dysfunction

BACKGROUND

Peak oxygen consumption is reduced in patients with symptomatic congestive heart failure, but functional capacity of patients with asymptomatic left ventricular systolic dysfunction has not been assessed by measurement of peak oxygen consumption attained during graded exercise testing.

METHODS AND RESULTS

Peak oxygen consumption, that is, aerobic capacity (VO2, mL/kg per minute), was determined during graded treadmill exercise using the modified Naughton protocol in 40 patients with left ventricular systolic dysfunction (mean ejection fraction ranging from 14% to 35%; mean, 29%) who, while not receiving any cardiac medications, were totally asymptomatic, and in 41 age-matched normal subjects. Peak exercise duration and VO2 were significantly lower in patients with asymptomatic left ventricular systolic dysfunction than in normal subjects (948 +/- 273 versus 1239 +/- 372 seconds, P < .001, and 22.1 +/- 5.9 versus 29.8 +/- 7.7 mL/kg per minute, respectively, P < .001), while asymptomatic patients and normal subjects reached similar respiratory equivalents (1.14 +/- 0.11 versus 1.11 +/- 0.11 [NS]) and level of perceived exertion, using the modified Borg scale (7.4 +/- 2.6 versus 8.1 +/- 1.5 [NS]). Heart rate, systemic blood pressure, and oxygen pulse response to peak exercise were significantly lower in asymptomatic patients than in normal subjects.

CONCLUSIONS

Although patients with left ventricular systolic dysfunction can be totally asymptomatic in their daily activities, they have experienced a substantial reduction in peak aerobic capacity when compared with normal subjects of similar age.

Pathophysiological correlates of increased serum tumor necrosis factor in patients with congestive heart failure. Relation to nitric oxide-dependent vasodilation in the forearm circulation

BACKGROUND

Tumor necrosis factor-alpha (TNF alpha), which we and others have shown to be elevated in patients with severe congestive heart failure (CHF), is involved in the regulation of nitric oxide metabolism. Whether increased concentrations of TNF alpha affect nitric oxide-mediated vasodilation in patients with CHF has not been studied previously.

METHODS AND RESULTS

Serum concentrations of TNF alpha, interleukin-1 (IL-1), interleukin-2 (IL-2), and interleukin-6 (IL-6) were determined in venous blood (pg/mL) from 17 patients with stable New York Heart Association classes II and III CHF (mean age, 58 +/- 11 years; mean left ventricular ejection fraction, 19.5 +/- 7.3) and 17 age-matched normal subjects with enzyme-linked immunosorbent assays (detection limit of assays, 20 pg/mL). Forearm blood flows were determined with plethysmography (mL/min per 100 mL) in 17 patients and 7 normal subjects in response to brachial artery administration of graded concentrations of acetylcholine (10(-6) mol/L and 10(-5) mol/L) and nitroglycerin (10(-7) mol/L and 10(-6) mol/L). Serum concentrations of TNF alpha were above the detection limits of the assay in 10 of 17 patients with CHF (mean serum concentration, 39.4 +/- 3.8 pg/mL). Forearm blood flow responses to acetylcholine and nitroglycerin were significantly greater in these 10 patients than in the 7 patients without detectable serum TNF alpha and were closely correlated with TNF alpha serum concentrations (r > or = .81, P < .01 and r > or = .65, P < .05 respectively). In 1 of 17 normal subjects, the serum concentration of TNF alpha was just above the detection limit of the assay. Serum concentrations of IL-2 were above the detection limit of the assay in 14 of 17 patients with CHF (mean serum concentration, 112 +/- 19 pg/mL). IL-2 was not detected in the serum of normal subjects. Serum concentrations of IL-1 and IL-6 were below the detection limit of the assays in all patients and normal subjects assayed.

CONCLUSIONS

Increased TNF alpha concentrations are closely correlated with forearm blood flow responses to regional administration of acetylcholine and nitroglycerin. The significant correlation between serum concentrations of TNF alpha and forearm blood flow responses to acetylcholine and nitroglycerin suggests that both the inducible and the constitutive forms of nitric oxide synthase are involved in the regulation of peripheral vasomotor tone in patients with CHF.

Enhancement of endothelium-dependent vasodilation by low-dose nitroglycerin in patients with congestive heart failure

BACKGROUND

Since organic nitroesters and endothelium-derived nitric oxide mediate vasodilation through a final common pathway, that is, by activation of soluble guanylate cyclase in vascular smooth muscle, nitroglycerin (NTG) could specifically enhance the endothelium-dependent vasodilatory response to acetylcholine (Ach) in patients with congestive heart failure (CHF) and endothelial cell dysfunction. Accordingly, the net effects of an intra-arterial infusion of NTG (10(-9) mol/L) on endothelium-dependent and endothelium-independent vasodilation were assessed in the forearm circulation of patients with CHF.

METHODS AND RESULTS

The forearm blood flow responses to intra-arterial administration of graded concentrations of Ach (10(-7) to 10(-5) mol/L) were determined by venous occlusion plethysmography (mL/min per 100 mL) in 18 patients with CHF and 5 age-matched normal subjects before and during intra-arterial infusion of NTG (10(-9) mol/L) for 20 minutes. In eight patients, the duration of the infusion of NTG (n = 5) or vehicle control solution (n = 3) was extended to 12 hours with measurement of the forearm blood flow responses to Ach at 20 minutes, 4 hours, and 12 hours. In five additional patients, forearm blood flow response to intra-arterial administration of two doses of phentolamine (0.05 and 0.5 mg) were determined before and during a 20-minute NTG infusion. Regional administration of NTG 10(-9) mol/L did not change resting forearm blood flow in either normal subjects or patients with CHF. Before administration of NTG 10(-9) mol/L, intra-arterial infusions of Ach 10(-7), 10(-5) and 10(-5) mol/L increased forearm blood flow to 14.7 +/- 6.2, 20.2 +/- 4.7, and 38.4 +/- 7.9 mL/min per 100 mL in normal subjects and to 4.1 +/- 0.8, 5.0 +/- 1.1, and 10.6 +/- 2.3 mL/min per 100 mL in patients with CHF. After administration of NTG 10(-9) mol/L for 20 minutes, the vasodilatory response to Ach significantly increased to 5.6 +/- 1.0, 6.9 +/- 1.6, and 17.7 +/- 3.4 mL/min per 100 mL in patients with CHF but did not change in normal subjects. The enhanced forearm blood flow responses to administration of Ach observed after 20 minutes of NTG administration in patients with CHF were sustained throughout a 12-hour NTG infusion. In contrast, regional administration of NTG did not change the vasodilatory responses to phentolamine.

CONCLUSIONS

NTG, when administered intra-arterially for 20 minutes at a dose that does not affect resting forearm blood flow, specifically increased the vasodilatory response to intra-arterial administration of Ach in patients with CHF but not in normal subjects. The vasodilatory response to Ach was consistently enhanced by low-dose NTG throughout a 12-hour period. The vasodilating effects of organic nitroesters on the peripheral vasculature of patients with CHF may result in part from an interaction with the vascular endothelium.

Ischemic hepatitis in a patient with congestive cardiomyopathy: an innovative approach to therapy using intravenous dobutamine

Patients who sustain a transient period of hypotension or low cardiac output can develop massive elevations of the serum transaminases without serum markers of acute hepatitis, a recent myocardial infarction or exposure to toxins and chemicals. This condition is often termed "ischemic hepatitis" (IH), with its pathological correlate being centrilobular necrosis. Recognition of IH can help in the appropriate management of these patients, and avoid unnecessary diagnostic testing. The authors describe a patient with congestive cardiomyopathy in whom IH developed as part of a complicated hospital course. The condition appeared to reverse with the administration of dobutamine, suggesting inotropic therapy as an appropriate treatment modality.

Peripheral factors in the management of congestive heart failure

Maladaptive changes in the periphery largely account for the symptomatology of patients with congestive heart failure (CHF). A decline in the systolic function of the left ventricle precipitates activation of neural and humoral systems to provide circulatory support. These include sympathetic release of norepinephrine, increases in angiotensin II, elevated levels of circulating arginine vasopressin, and impairment of the counterregulatory function of atrial natriuretic peptide. The resultant circulatory changes are ultimately responsible for the declining function of the peripheral vasculature and skeletal muscles of patients with CHF. In the peripheral vasculature, impaired vasodilatory capacity results from excess vessel wall stiffness, endothelial dysfunction, and structural abnormalities. The skeletal muscles develop poor aerobic capacity as a result of a change in predominant fiber type and excess reliance on glycolytic metabolic pathways. Physical deconditioning induced by symptoms tends to further promote these peripheral changes. Therapeutic interventions with symptomatic and prognostic benefits have essentially been targeted at the periphery. Angiotensin converting enzyme inhibitors may act by normalizing electrolyte and water balance, improving vascular endothelial function, and reversing structural changes in peripheral vessels. Exercise training appears to exert its benefit at the level of the vascular endothelium. Advances in the therapy of CHF depend on a greater understanding of changes in the periphery.

Lactate turnover at rest and during submaximal exercise in patients with heart failure

Systemic and lower limb skeletal muscle lactate metabolism was studied in 10 men with congestive heart failure by use of a primed continuous intravenous infusion of L-(+)-[U-14C]lactate. Arterial and deep femoral venous blood samples were obtained at rest and during 30 min of submaximal exercise. Systemic lactate metabolic turnover rate (Rd) was determined using Steele's isotopic steady-state equation (Rd = isotopic infusion rate/arterial specific activity). Plasma lactate concentrations in the artery and deep femoral vein did not change significantly from resting values during exercise (1.11 +/- 0.13 vs. 1.26 +/- 0.12 and 1.27 +/- 0.12 vs. 1.30 +/- 0.12 mM, respectively), whereas Rd increased from 22.5 +/- 1.8 to 41.6 +/- 4.8 mumol.kg-1.min-1 (P < 0.005). Rd did not significantly correlate with arterial lactate concentration during rest or exercise. Because of simultaneous uptake and release of lactate in skeletal muscle, arterial and deep femoral venous lactate concentrations are not closely related to either systemic or lower limb skeletal muscle lactate metabolism in patients with congestive heart failure.

Regional specificity of peak hyperemic response in patients with congestive heart failure: correlation with peak aerobic capacity

OBJECTIVES

The aim of this study was to compare peak reactive hyperemic blood flows in the forearm and calf of patients with congestive heart failure and in age- and gender-matched normal subjects. In addition, we attempted to correlate peak oxygen consumption with forearm and calf peak reactive hyperemic flows in the patients with heart failure.

BACKGROUND

Disparate results have been reported regarding forearm peak reactive hyperemia in patients with congestive heart failure. Because training significantly increases peak reactive hyperemic flow in normal subjects, we hypothesized that in patients with congestive heart failure who curtail walking because of exertional symptoms, calf peak reactive hyperemic flow would be preferentially attenuated and that impairment of calf vasculature may correlate with peak oxygen consumption.

METHODS

Forearm and calf blood flows were measured by venous occlusive plethysmography at rest and after 5 min of arterial occlusion in 46 patients with congestive heart failure and 7 age- and gender-matched normal subjects. Peak oxygen consumption was measured during graded exercise on a bicycle ergometer.

RESULTS

Calf peak reactive hyperemic flow was lower in patients with congestive heart failure than in normal subjects (22 +/- 1 vs. 32.5 +/- 3.5 ml/min per 100 ml, p < 0.001), whereas forearm peak reactive hyperemic flows were similar in the two groups. Calf peak reactive hyperemic flow was linearly related to peak oxygen consumption (r = 0.58, p < 0.0001), but forearm peak reactive hyperemic flow was not. Forearm and calf peak reactive hyperemic flows were not related at rest or after 5 min of arterial occlusion in the patients with heart failure.

CONCLUSIONS

Calf peak reactive hyperemic flow is reduced in patients with congestive heart failure, whereas forearm peak reactive hyperemic flow is identical to that of age- and gender-matched normal subjects. Calf peak reactive hyperemic flow is linearly related to peak oxygen consumption in patients with congestive heart failure, but forearm peak reactive hyperemic flow is not.

Diagnostic value of left ventricular dyssynergy patterns in ischemic and non-ischemic cardiomyopathy

BACKGROUND

The distinction between ischemic and non-ischemic cardiomyopathy has important clinical implications. The objective of the present study was to investigate whether left ventricular dyssynergy patterns, detected by quantitative analysis of ultrasound images, differed in these two pathological processes.

METHODS

Fifty-six consecutive patients with congestive heart failure (New York Heart Association functional class II-IV) secondary to depressed left ventricular systolic function (ejection fraction < or = 35% during diagnostic cardiac catheterization) were studied. Twenty patients were eliminated from further analysis because they met one or more exclusion criteria. The remaining 36 were divided into two groups based on the presence (ischemic cardiomyopathy) or absence (non-ischemic cardiomyopathy) of a > or = 50% narrowing of the luminal diameter in one or more coronary arteries. In all patients, a standard two-dimensional echocardiographic study was obtained. Apical four- and two-chamber views with optimal endocardial and epicardial resolution were selected for analysis, and the left ventricular contour was divided into six segments of interest. Optimal endocardial and epicardial resolution were defined according to an original internal quality score system. For each of the six segments of interest, regional ejection fraction and regional segmental thickening were estimated. Data analysis was then performed on the average values of regional ejection fraction and regional segmental thickening obtained across the entire left ventricular contour. In each patient, regional ejection fraction range and regional segmental thickening range were calculated by subtracting the minimum from the maximum value of regional ejection fraction and regional segmental thickening obtained across a left ventricular contour.

RESULTS

Regional ejection fraction and regional segmental thickening did not differ significantly between the two groups. However, regional ejection fraction range and regional segmental thickening range were significantly greater in patients with ischemic cardiomyopathy than in patients with non-ischemic cardiomyopathy [28.32 +/- 11.17 versus 14.74 +/- 7.73% (P < 0.001) and 47.80 +/- 16.00 versus 24.64 +/- 9.39% (P < 0.001), respectively]. Overlap of findings was observed in 20% of the values for regional ejection fraction range but in only 14% of those for regional segmental thickening range.

CONCLUSIONS

Patients with ischemic cardiomyopathy demonstrate a non-uniform dyssynergy that can be differentiated from a more uniform hypokinesis observed in those with non-ischemic cardiomyopathy. Computerized ultrasonic image analysis can distinguish characteristic dyssynergic patterns in patients with cardiomyopathy. Measurements of segmental wall thickening provide a more accurate assessment of regional function.

Heart failure: its progression and its therapy

The complex pathology that leads to heart failure has hampered the search for optimal therapy. Even so, ACE inhibitors have become a cornerstone of treatment. After an acute MI, the goal of ACE inhibition is to limit LV remodeling and progression to ischemic cardiomyopathy and congestive failure. In advanced failure, the goal is to reverse peripheral vascular changes and ameliorate symptoms.

Impaired acetylcholine-mediated vasodilation in patients with congestive heart failure. Role of endothelium-derived vasodilating and vasoconstricting factors

BACKGROUND

The vasodilatory response to intra-arterial administration of acetylcholine is reduced in patients with congestive heart failure compared with that of normal subjects. The reduced response to acetylcholine may be related to decreased endothelial release of nitric oxide, interaction with peripheral alpha-adrenergic transmission, or production of cyclooxygenase-dependent vasoconstricting substances. The extent to which each of these mechanisms contributes to the reduced vasodilatory response to acetylcholine in patients with congestive heart failure is not known.

METHODS AND RESULTS

Thirty-one patients with congestive heart failure (New York Heart Association functional class II-III) and five age-matched normal subjects were studied. Regional vascular responses in the forearm to infusions of acetylcholine, an endothelium-dependent vasodilator (10(-7) to 10(-5) mol/L) and nitroglycerin, an endothelium-independent vasodilator (10(-6) mol/L) in the brachial artery were determined with venous occlusion plethysmography before and after regional alpha-adrenergic blockade with intra-arterial phentolamine (25 micrograms/min) and systemic cyclooxygenase with oral indomethacin (50 mg). Administration of phentolamine significantly increased resting baseline forearm blood flow in 11 patients with congestive heart failure (2.9 +/- 0.4 to 5.4 +/- 0.8 mL.min-1.100 mL-1) and normal subjects (4.6 +/- 0.3 to 11.3 +/- 2.1 mL.min-1.100 mL-1). Before administration of phentolamine, intra-arterial infusions of acetylcholine 10(-7), 10(-6), and 10(-5) mol/L increased forearm blood flow to 4.0 +/- 1.0, 6.0 +/- 1.7, and 16.1 +/- 4.0 mL.min-1.100 mL-1, respectively, in patients with congestive heart failure and to 14.7 +/- 6.2, 20.2 +/- 4.7, and 38.7 +/- 7.9 mL.min-1.100 mL-1, respectively, in normal subjects. After administration of phentolamine, the vasodilatory responses to intra-arterial infusions of acetylcholine and nitroglycerin did not change in either patients or normal subjects. Administration of indomethacin did not alter resting forearm blood flow in 15 patients with congestive heart failure (2.7 +/- 0.4 to 2.7 +/- 0.4 mL.min-1.100 mL-1) or normal subjects (4.6 +/- 0.3 to 5.4 +/- 0.8 mL.min-1.100 mL-1). Administration of indomethacin significantly increased the vasodilatory response to infusion of acetylcholine by an average of 39% in patients with congestive heart failure but did not change the vasodilatory response to acetylcholine in normal subjects. In patients with congestive heart failure, baseline forearm blood flow and the vasodilatory responses to intra-arterial infusions of acetylcholine and nitroglycerin were significantly less than those of normal subjects both before and after administration of phentolamine and indomethacin.

CONCLUSIONS

The reduced vasodilatory response to intra-arterial infusion of acetylcholine in patients with congestive heart failure probably results from several coexistent abnormalities in peripheral vascular function, including abnormal production of cyclooxygenase-dependent vasoconstricting factor, impaired endothelial release of nitric oxide, and decreased vascular smooth muscle responsiveness to cyclic GMP-mediated vasodilation.

Low incidence of stroke in ambulatory patients with heart failure: a prospective study

The current study was undertaken to determine prospectively the risk of cerebral thromboembolism and the prognostic significance of left ventricular thrombus in ambulatory patients with chronic congestive heart failure. A total of 264 ambulatory patients (mean age 62 years, mean left ventricular ejection fraction 27%) were followed prospectively for 24 +/- 9 months to determine the incidence of nonhemorrhagic stroke, transient ischemic attack, and mortality. Two-dimensional echocardiographic studies, performed for clinical indications other than previous systemic thromboembolism in 109 patients, were analyzed to relate the presence of left ventricular thrombus to subsequent outcome. Nine cerebral thromboembolic events occurred in 264 patients during the two-year mean follow-up period, yielding a rate of 1.7 thromboembolic events per 100 patient-years of follow-up. Known risk factors for stroke (hypertension, diabetes mellitus, and/or atrial fibrillation) were present in all nine patients with cerebral thromboembolic events. The 109 patients with echocardiographic studies had more severe heart failure than patients without echocardiographic studies (functional class 2.6 vs 2.1, p < 0.01), greater risk of a thromboembolic event (2.4 vs 1.4 events/100 patient-years of follow-up, p < 0.01), and higher mortality (21.3 vs 5.5 deaths/100 patient-years, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Active skeletal muscle mass and cardiopulmonary reserve. Failure to attain peak aerobic capacity during maximal bicycle exercise in patients with severe congestive heart failure

BACKGROUND

In addition to depressed cardiac reserve, peripheral factors may contribute to limit maximal exercise capacity in patients with congestive heart failure (CHF). To investigate the role of reduced active skeletal muscle mass, peak oxygen uptake (VO2, milligrams per kilogram per minute) was determined during maximal symptom-limited exercise involving the lower limbs (LL) alone and the lower limbs and upper limbs (LL+UL) combined in patients with CHF and in normal subjects of similar age and sex.

METHODS AND RESULTS

LL bicycle exercise was performed upright with a ramp protocol and continuous expired gas analysis. When respiratory exchange ratio (RER) reached 1.0, UL exercise was initiated at constant load with the use of a cranking device positioned at shoulder level. LL exercise alone and combined LL+UL exercise were performed on separate days in randomized order by 24 patients with CHF and seven normal subjects. In patients with CHF, peak VO2 was greater during combined LL+UL exercise than during LL exercise alone, i.e., 15.8 +/- 0.8 versus 14.2 +/- 0.9 ml.kg-1.min-1 (p < 0.001), whereas in normal subjects, maximal VO2 was similar during the two tests, i.e., 26.7 versus 26.2 ml.kg-1.min-1 (NS). The increase in peak VO2 during combined LL+UL exercise relative to LL exercise alone was almost exclusively observed in patients with peak VO2 < 15 ml.kg-1.min-1 (mean increase, 21.7 +/- 4.1%). Peak VO2 during combined LL and UL exercise did not increase relative to LL exercise alone in patients with peak VO2 > 15 ml.kg-1.min-1 and in normal subjects of similar age and sex, i.e., 0.1 +/- 4.0% and 2.0 +/- 2.3% respectively.

CONCLUSIONS

In contrast to normal subjects and patients with moderate CHF, patients with severe CHF do not exhaust their cardiopulmonary reserve during symptom-limited maximal LL exercise on a bicycle.

Anaerobic threshold detection in patients with congestive heart failure

Anaerobic threshold measurements determined either invasively by analysis of arterial lactate concentration (lactate threshold) or noninvasively by respiratory gas exchange analysis (ventilatory threshold) were compared in patients with chronic congestive heart failure. Sixteen patients performed symptom-limited maximal exercise on a bicycle ergometer using a continuous ramp protocol with measurement of arterial lactate concentration at 1 minute intervals, and continuous breath-by-breath analysis of respiratory gas exchange. A specific lactate threshold point was detected in only 7 patients. These 7 patients had significantly greater peak oxygen uptake than did the 9 in whom no specific lactate threshold point was detected (15.9 +/- 1.0 vs 10.5 +/- 0.5 ml/kg/min; p less than 0.05). Ventilatory threshold significantly correlated with lactate threshold in these 7 patients. In the remaining 9 patients, neither lactate nor ventilatory threshold could be reliably determined with methods used in the present study.

Characteristics of peak aerobic capacity in symptomatic and asymptomatic subjects with left ventricular dysfunction. The Studies of Left Ventricular Dysfunction (SOLVD) Investigators

Expired gas analysis was used to determine the aerobic exercise performance of subjects with depressed left ventricular (LV) systolic function and congestive heart failure (CHF). To determine whether subjects with no or minimal CHF have better aerobic exercise performance than do those with overt CHF, oxygen consumption (VO2) at anaerobic threshold (AT) and peak exercise was measured in 184 subjects with LV ejection fraction less than or equal to 0.35 who participated in the Studies of Left Ventricular Dysfunction. Subjects were divided into those with overt CHF needing treatment (treatment trial; n = 20) and those who had neither overt CHF nor treatment for CHF (prevention trial; n = 164). Treatment trial subjects had a lower LV ejection fraction (0.25 +/- 0.07) than did prevention trial ones (0.29 +/- 0.05; p = 0.001), but there were no differences in age, gender, body weight, resting heart rate and blood pressure. Treadmill exercise testing was performed after 2 to 3 weeks of placebo (no angiotensin-converting enzyme inhibitor) treatment. Treatment trial subjects exercised for a shorter time (493 +/- 160 seconds) and attained a lower peak VO2 (13 +/- 4 ml/kg/min) and VO2 at AT (11 +/- 4 ml/kg/min) than did prevention trial ones (842 +/- 277 seconds, and 20 +/- 6 and 16 +/- 5 ml/kg/min, respectively). Analysis of covariance showed that the differences in peak VO2 and VO2 at AT were statistically significant between the 2 trials after adjusting for age, gender, LV ejection fraction and New York Heart Association functional class.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical analysis of methods for assessing regional blood flow and their reliability in clinical medicine

The advantages and inadequacies of the currently available techniques to measure regional blood flow in the lower limbs are being reviewed. Thermodilution technique and local 133xenon washout technique have the advantage of allowing determination of blood flow during exercise, while venous occlusion plethysmography and pulsed-Doppler duplex ultrasonography only allow determination of blood flow at rest. Overall, measurements of lower limb blood flow are not highly reproducible by any technique, and the variability in measurements of regional blood flow should lead to careful interpretation of derived parameters such as vascular conductance and resistance. Determination of vascular input impedance by Fourier analysis of pressure data, recorded with high fidelity catheter, and flow velocity measurements obtained transcutaneously by Doppler ultrasonography, may offer a more accurate quantitative analysis of the characteristics of the lower limb vascular system.

Impaired endothelium-mediated vasodilation in the peripheral vasculature of patients with congestive heart failure

Impaired endothelial-dependent vasodilation has been demonstrated in two animal models of congestive heart failure and in the coronary circulation of patients with idiopathic dilated cardiomyopathy. To determine whether this impairment contributes to the abnormal peripheral vasomotor tone in patients with congestive heart failure, the local vascular response to intraarterial infusions of graded concentrations (10(-8) M to 10(-5) M) of acetylcholine (an endothelial-dependent vasodilator) and nitroglycerin (a direct-acting vasodilator) was studied in the superficial femoral artery of 19 patients with congestive heart failure (New York Heart Association classes I to IV) and 6 age-matched normal control subjects. The local vascular response was determined from the arterial blood flow velocity pattern obtained by transcutaneous Doppler ultrasonography. Acetylcholine, 10(-5) M, induced a pattern characteristic of vasodilation in all six normal subjects; mean blood flow velocity for the group significantly increased from 11.9 +/- 2.7 to 44.8 +/- 20.9 cm/s (p less than 0.05). In contrast, the same dose of acetylcholine induced a blood flow velocity pattern characteristic of vasodilation in only 4 of the 19 patients with congestive heart failure. Group mean blood flow velocity did not change significantly. Nitroglycerin, 10(-7) M, induced vasodilation in all 6 normal subjects but in only 1 of 19 patients. Nitroglycerin, 10(-5) M, was administered to 10 patients; all 10 demonstrated a pattern characteristic of vasodilation. Thus, acetylcholine-mediated endothelial-dependent vasodilation appears to be impaired in the peripheral vasculature of patients with congestive heart failure. Both endothelial dysfunction and abnormal vascular smooth muscle responsiveness may contribute to abnormal peripheral vasomotor tone.

A multicenter, randomized, double-blind, placebo-controlled trial of pimobendan, a new cardiotonic and vasodilator agent, in patients with severe congestive heart failure

Pimobendan, a new oral cardiotonic and vasodilator agent, increases myocardial contractile force through specific inhibition of phosphodiesterase type III and increased calcium sensitivity of the myocardial contractile elements. The effects of pimobendan on left ventricular performance and maximal exercise capacity were studied in a multicenter, randomized, double-blind, placebo-controlled trial involving 52 patients with severe congestive heart failure despite diuretics, digoxin, and angiotensin-converting enzyme inhibitors. The acute hemodynamic evaluation included three single doses of 2.5, 5.0, and 10.0 mg of oral pimobendan, which was subsequently administered at a daily dose of 5 or 10 mg for 4 weeks. Acute administration of pimobendan significantly increased the resting cardiac index and lowered pulmonary capillary wedge pressure in a dose-dependent manner, whereas heart rate and systemic arterial pressure were not substantially altered. Patients receiving pimobendan, 5 and 10 mg daily, had a significantly greater increase in maximal exercise duration than those receiving placebo, that is, 144 +/- 30 and 124 +/- 33 seconds versus 58 +/- 25 seconds (p = 0.05). Peak oxygen uptake increased by 1.7 +/- 0.8 and 2.2 +/- 1.3 ml/kg/min in patients receiving pimobendan at a daily dose of 5 and 10 mg, respectively, whereas it decreased by 0.1 +/- 0.6 ml/kg/min in patients receiving placebo (p = 0.06). Thus pimobendan acutely improves resting left ventricular performance and chronically increases exercise duration and peak oxygen uptake in patients with severe congestive heart failure concomitantly treated with digoxin, diuretics, and angiotensin-converting enzyme inhibitors.

Control of arteriolar resistance in heart failure. Partial attenuation of specific phosphodiesterase inhibitor-mediated vasodilation by digitalis glycosides

BACKGROUND

The vasodilatory response to local specific type III phosphodiesterase inhibition with amrinone was evaluated before and immediately after local administration of digoxin in 14 patients with severe congestive heart failure (CHF).

METHODS AND RESULTS

A 3F polyethylene catheter was inserted into the common femoral artery for drug administration and pressure monitoring. Mean blood flow velocity (MBFV) was continuously determined in the superficial femoral artery by transcutaneous Doppler ultrasonography. After intra-arterial administration of 10 mg amrinone, group MBFV increased from 7.7 +/- 1.4 to 16.0 +/- 2.1 cm/sec (p less than 0.05, n = 10). Local administration of 20 micrograms digoxin, which was infused over 20 minutes, did not alter group MBFV (i.e., 8.2 +/- 1.6 versus 7.6 +/- 1.5 cm/sec; p = NS, n = 10). The second administration of 10 mg amrinone, which immediately followed completion of local digoxin infusion, increased group MBFV but to a lesser extent than that produced by the first amrinone administration (i.e., 11.9 +/- 1.9 versus 16.0 +/- 2.1 cm/sec; p less than 0.05, n = 10). When placebo was administered instead of digoxin, group MBFV was similar after the first and second administrations of amrinone (i.e., 15.3 +/- 3.3 versus 15.6 +/- 3.8 cm/sec; p = NS, n = 4).

CONCLUSIONS

Although local administration of digoxin did not significantly alter baseline vascular tone in patients with CHF, it substantially decreased the direct vasodilatory effect induced by specific type III phosphodiesterase with amrinone.