Mechanisms involved in the response to prolonged infusion of atrial natriuretic factor in patients with chronic heart failure

Impact of vasodilators on diuretic response in patients with congestive heart failure: A mechanistic trial of cimlanod (BMS-986231)

AIM

To investigate the effects of Cimlanod, a nitroxyl donor with vasodilator properties, on water and salt excretion after an administration of an intravenos bolus of furosemide.

METHODS AND RESULTS

In this randomized, double-blind, mechanistic, crossover trial, 21 patients with left ventricular ejection fraction <45%, increased plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and receiving loop diuretics were given, on separate study days, either an 8 h intravenous (IV) infusion of cimlanod (12 μg/kg/min) or placebo. Furosemide was given as a 40 mg IV bolus four hours after the start of infusion. The primary endpoint was urine volume in the 4 h after the bolus of furosemide during infusion of cimlanod compared with placebo. Median NT-proBNP at baseline was 1487 (interquartile range: 847-2665) ng/L. Infusion of cimlanod increased cardiac output and reduced blood pressure without affecting cardiac power index consistent with its vasodilator effects. Urine volume in the 4 h post-furosemide was lower with cimlanod (1032 ± 393 ml) versus placebo (1481 ± 560 ml) (p = 0.002), as were total sodium excretion (p = 0.004), fractional sodium excretion (p = 0.016), systolic blood pressure (p < 0.001), estimated glomerular filtration rate (p = 0.012), and haemoglobin (p = 0.010), an index of plasma volume expansion.

CONCLUSIONS

For patients with heart failure and congestion, vasodilatation with agents such as cimlanod reduces the response to diuretic agents, which may offset any benefit from acute reductions in cardiac preload and afterload.

Benefit and harm of intravenous vasodilators across the clinical profile spectrum in acute cardiogenic pulmonary oedema patients

BACKGROUND

The absence of high quality, large-scale data that indicates definitive mortality benefits does not allow for firm conclusions on the role of intravenous vasodilators in acute heart failure. We aimed to investigate the associations between intravenous vasodilators and clinical outcomes in acute heart failure patients, with a specific focus on patient profiles and type of vasodilators.

METHODS

Data of 26,212 consecutive patients urgently hospitalised for a primary diagnosis of acute heart failure between 2009 and 2015 were extracted from a government-funded multicentre data registration system. Propensity scores were calculated with multiple imputations and 1:1 matching performed between patients with and without vasodilator use. The primary endpoint was inhospital mortality.

RESULTS

On direct comparison of the vasodilator and non-vasodilator groups after propensity score matching, there were no significant differences in the inhospital mortality rates (7.5% vs. 8.8%, respectively; P=0.098) or length of intensive/cardiovascular care unit stay and hospital stay between the two groups. However, there was a substantial difference in baseline systolic blood pressure by vasodilator type; favourable impacts of vasodilator use on inhospital mortality were observed among patients who had higher systolic blood pressures and those who had no atrial fibrillation on admission. Furthermore, when compared to nitrates, the use of carperitide (natriuretic peptide agent) was significantly associated with worse outcomes, especially in patients with intermediate systolic blood pressures.

CONCLUSIONS

In acute heart failure patients, vasodilator use was not universally associated with improved inhospital outcomes; rather, its effect depended on individual clinical presentation: patients with higher systolic blood pressure and no atrial fibrillation seemed to benefit maximally from vasodilators.

TRIAL REGISTRATION

UMIN-CTR identifier, UMIN000013128.

Rationale and Design of Low-dose Administration of Carperitide for Acute Heart Failure (LASCAR-AHF)

BACKGROUNDS

Despite current therapies, acute heart failure (AHF) remains a major public health burden with high rates of in-hospital and post-discharge morbidity and mortality. Carperitide is a recombinantly produced intravenous formulation of human atrial natriuretic peptide that promotes vasodilation with increased salt and water excretion, which leads to reduction of cardiac filling pressures. A previous open-label randomized controlled study showed that carperitide improved long-term cardiovascular mortality and heart failure (HF) hospitalization for patients with AHF, when adding to standard therapy. However, the study was underpowered to detect a difference in mortality because of the small sample size.

METHODS

Low-dose Administration of Carperitide for Acute Heart Failure (LASCAR-AHF) is a multicenter, randomized, open-label, controlled study designed to evaluate the efficacy of intravenous carperitide in hospitalized patients with AHF. Patients hospitalized for AHF will be randomly assigned to receive either intravenous carperitide (0.02 μg/kg/min) in addition to standard treatment or matching standard treatment for 72 h. The primary end point is death or rehospitalization for HF within 2 years. A total of 260 patients will be enrolled between 2013 and 2018.

CONCLUSION

The design of LASCAR-AHF will provide data of whether carperitide reduces the risk of mortality and rehospitalization for HF in selected patients with AHF.

Effect of carperitide on in-hospital mortality of patients admitted for heart failure: propensity score analyses

Although a previous randomized study showed that the use of atrial natriuretic peptide (carperitide) improved the long-term prognosis of patients with heart failure, its effect on short-term prognosis remains unclear. We retrospectively identified patients who were admitted to our tertiary-care center with acute decompensated heart failure (ADHF) between April 2009 and December 2013.We divided the eligible patients into two groups: patients who started receiving carperitide on the day of admission (carperitide group) and those who did not receive carperitide during hospitalization (control group). We compared the in-hospital mortality between the two groups using propensity scores derived from 40 baseline variables. We identified 879 eligible patients (mean age, 75.2 years; male, 56.7%), including 336 (38.2%) in the carperitide group and 543 (61.8%) in the control group. One-to-one propensity score matching created 177 pairs. Although the unmatched analysis found a significantly lower in-hospital mortality in the carperitide group than in the control group (3.3% vs. 7.9%, respectively, p = 0.005), the propensity score-matched analysis found no significant difference in in-hospital mortality between the two groups [4.0% vs. 5.1%, p = 0.609; risk difference, -1.1%, 95% confidence interval (CI), -5.5-3.2%]. Logistic regression analysis with adjustment for propensity scores also found no significant association between carperitide use and in-hospital mortality (adjusted odds ratio, 0.61; 95% CI, 0.29 to 1.28; p = 0.605). The present retrospective study showed that carperitide use as the initial treatment was not significantly associated with lower in-hospital mortality in patients with ADHF.

Endoluminal Grafting for Aneurysmal and Occlusive Disease in the Superficial Femoral Artery: Early Experience

Purpose:

To examine whether endoluminal grafts (ELGs) of radially expandable polytetrafluoroethylene (PTFE) can successfully form durable internal conduits to revascularize lengthy occlusive disease and exclude aneurysms in the femoropopliteal (FP) arteries.

Methods:

Under protocol, implantation of an unpredilated PTFE tube ELG anchored with Palmaz stents using a low-profile percutaneous delivery system was attempted in 50 symptomatic patients for a variety of pathologies: (1) restenosis; (2) complex lesions unlikely to be treated successfully with other endoluminal therapies; (3) acute angioplasty failure; and (4) aneurysms. There were 37 occlusions, 14 stenoses, and 2 long, combined stenoticaneurysmal lesions in 47 native arteries, 5 FP grafts, and 1 femorotibial (FT) vein graft. Thirty-two percent of the patients had ≤ 1 vessel runoff. The average lesion length was 20.4 ± 11.4 cm (range 1.5 to 40), and the mean preoperative ankle-brachial index (ABI) at rest was 0.53 ± 0.14.

Results:

In a 20-month period through April 1995, 50 patients (34 males, 16 females; mean age 69.5 years, range 45 to 87) underwent 54 procedures in 53 limbs; 55 ELGs were successfully deployed in 51 limbs; 2 patients were converted to FP bypass owing to technical problems (96% procedural success). There were 18 inhospital complications: 1 distal wire dissection repaired with an additional ELG; 2 hematomas requiring surgical repair; 1 graft collapse; 1 pseudoaneurysm at the site of a mid-ELG leak; 7 minor access sequelae; and 6 acute ELG thromboses, 4 treated with lytic therapy and balloon dilation, 1 with open thrombectomy, and 1 with bypass grafting. The mean postoperative ABI was 1.01 ± 0.10. During the 30-day postprocedure period, 2 ELGs rethrombosed and 2 other limbs (3 ELGs) occluded; 1 thrombosis and 1 rethrombosis were lysed successfully, but the other 2 patients had an FP bypass. Over the mean 8.3 ± 5.5 month follow-up, 6 additional ELGs occluded and 1 reoccluded; 4 were successfully treated by endovascular techniques for a primary patency of 72% and secondary patency of 84% by life-table analysis.

Conclusions:

Endovascular grafting is a conceptually attractive technique that has the potential to expand the current boundaries of interventional treatment. This preliminary experience attests to the feasibility and safety of ELG deployment in the superficial femoral arteries. Whether such a device can match the durability of classical revascularization techniques remains to be determined in clinical trials when device configurations and deployment techniques have been standardized.

Efficacy and Safety of 1-Hour Infusion of Recombinant Human Atrial Natriuretic Peptide in Patients With Acute Decompensated Heart Failure: A Phase III, Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial

The aim of the study was to evaluate the efficacy and safety of 1-h infusion of recombinant human atrial natriuretic peptide (rhANP) in combination with standard therapy in patients with acute decompensated heart failure (ADHF). This was a phase III, randomized, double-blind, placebo-controlled, multicenter trial. Eligible patients with ADHF were randomized to receive a 1-h infusion of either rhANP or placebo at a ratio of 3:1 in combination with standard therapy. The primary endpoint was dyspnea improvement (a decrease of at least 2 grades of dyspnea severity at 12 h from baseline). Reduction in pulmonary capillary wedge pressure (PCWP) 1 h after infusion was the co-primary endpoint for catheterized patients. Overall, 477 patients were randomized: 358 (93 catheterized) patients received rhANP and 118 (28 catheterized) received placebo. The percentage of patients with dyspnea improvement at 12 h was higher, although not statistically significant, in the rhANP group than in the placebo group (32.0% vs 25.4%, odds ratio=1.382, 95% confidence interval [CI]: 0.863-2.212, P = 0.17). Reduction in PCWP at 1 h was significantly greater in patients treated with rhANP than in patients treated with placebo (-7.74 ± 5.95 vs -1.82 ± 4.47 mm Hg, P < 0.001). The frequencies of adverse events and renal impairment within 3 days of treatment were similar between the 2 groups. Mortality at 1 month was 3.1% in the rhANP group vs 2.5% in the placebo group (hazard ratio = 1.21, 95% CI: 0.34-4.26; P > 0.99). 1-h rhANP infusion appears to result in prompt, transient hemodynamic improvement with a small, nonsignificant, effect on dyspnea in ADHF patients receiving standard therapy. The safety of 1-h infusion of rhANP seems to be acceptable. (WHO International Clinical Trials Registry Platform [ICTRP] number, ChiCTR-IPR-14005719.).

Efficacy and safety of short-term administration of recombinant human atrial natriuretic peptide (rhANP) for congestive heart failure: a phase II, multicentre randomized controlled dose-finding study

WHAT IS KNOWN AND OBJECTIVE

Although the long-term infusion of ANP has proved effective to treat heart failure, no published randomized controlled study has been reported to confirm the efficacy of the short-term ANP infusion in congestive heart failure (CHF) patients. This study was designed to assess the efficacy and safety of short-term infusion of recombinant human atrial natriuretic peptide (rhANP) in CHF patients.

METHODS

A total of 48 patients with CHF were enrolled and randomized into four groups, treated with standard therapy or rhANP (0·05, 0·1 or 0·2 μg/kg/min) for 1-hour infusion in addition to standard therapy. The hemodynamics were assessed for 12 h by Swan-Ganz catheter.

RESULTS AND DISCUSSION

The effect of the 0·05 μg/kg/min rhANP dose group on CO was modest and transient. The 0·2 μg/kg/min rhANP dose group tended to be associated with better effect on SV, CO and dyspnoea improvement, but modest effect on PCWP and more adverse events probably attributed to the study drug. However, the 0·1 μg/kg/min rhANP infusion was well tolerated and effective both on PCWP decrease (maximum:-9·46 ± 5·81 mmHg compared with baseline (P = 0·0002) and -6·75 mmHg compared with standard therapy, the 95% confidential interval [-13·43, -0·06 mmHg] at 1 h) and CO increase (maximum: 1·02 ± 1·43 L/min [P = 0·0308] at 1 h).

WHAT IS NEW AND CONCLUSION

In this small-sample study, 1-hour infusion of rhANP produced beneficial hemodynamic effects in CHF patients compared with standard therapy, and it was well tolerated. 0·1 μg/kg/min may be the optimum dose for short-term rhANP infusion to treat CHF for the further large sample trial before clinical application.

Glucocorticoids improve renal responsiveness to atrial natriuretic peptide by up-regulating natriuretic peptide receptor-A expression in the renal inner medullary collecting duct in decompensated heart failure

In heart failure, the renal responsiveness to exogenous and endogenous atrial natriuretic peptide (ANP) is blunted. The mechanisms of renal hyporesponsiveness to ANP are complex, but one potential mechanism is decreased expression of natriuretic peptide receptor-A (NPR-A) in inner medullary collecting duct (IMCD) cells. Newly emerging evidence shows that glucocorticoids could produce potent diuresis and natriuresis in patients with heart failure, but the precise mechanism is unclear. In the present study, we found dexamethasone (Dex) dramatically increased the expression of NPR-A in IMCD cells in vitro. The NPR-A overexpression induced by Dex presented in a time- and dose-dependent manner, which emerged after 12 h and peaked after 48 h. The cultured IMCD cells were then stimulated with exogenous rat ANP. Consistent with the findings with NPR-A expression, Dex greatly increased cGMP (the second messenger for the ANP) generation in IMCD cells, which presented in a time- and dose-dependent manner as well. In rats with decompensated heart failure, Dex dramatically increased NPR-A expression in inner renal medulla, which was accompanied by a remarkable increase in renal cGMP generation, urine flow rate, and renal sodium excretion. It is noteworthy that Dex dramatically lowered plasma ANP, cGMP levels, and left ventricular end diastolic pressure. These favorable effects induced by Dex were glucocorticoid receptor (GR)-mediated and abolished by the GR antagonist 17β-hydroxy-11β-[4-dimethylamino phenyl]-17α-[1-propynyl]estra-4,9-dien-3-one (RU486). Collectively, glucocorticoids could improve renal responsiveness to ANP by up-regulating NPR-A expression in the IMCD and induce a potent diuretic action in rats with decompensated heart failure.

Effects of carperitide on the long-term prognosis of patients with acute decompensated chronic heart failure: the PROTECT multicenter randomized controlled study

BACKGROUND

Carperitide is used to treat acute decompensated heart failure (ADHF), but its effects on long-term prognosis have not been studied.

METHODS AND RESULTS

A multicenter randomized controlled study of 49 patients with ADHF was performed to clarify the drug's effects on long-term prognosis. Low-dose carperitide (0.01-0.05 microg x kg(-1 ) x min(-1)) was infused for 72 h as the initial treatment (n=26), whereas in the control group (n=23), standard medical treatment other than carperitide was given without limitation. Anti-aldosterone drugs were prohibited in both groups. During carperitide infusion, significant increases of the atrial natriuretic peptide and cyclic GMP levels and a significant decrease in the heart-type fatty acid-binding protein/serum creatinine ratio were observed, suggesting inhibition of myocyte cell membrane damage. On the other hand, no significant differences in the plasma brain natriuretic peptide, troponin T, and creatinine levels were noted in either group. During 18-month follow-up, significant reductions of death and rehospitalization occurred in the carperitide vs control group (11.5% vs 34.8%; p=0.0359). Cox regression analysis revealed that randomization to carperitide (p=0.020), pretreatment systolic blood pressure >or=140 mmHg (p=0.043), and beta-blocker therapy (p=0.016) were independent predictors for freedom from cardiac events.

CONCLUSIONS

Acute-phase low-dose carperitide infusion improved the long-term prognosis of patients with ADHF.

Atrial natriuretic peptide and related peptides

In recent years, biomarkers have been recognized as important tools for diagnosis, risk stratification, and therapeutic decision-making in cardiovascular diseases. Currently, the clinical potential of several natriuretic peptides is under scientific investigation. The well-known counter-regulatory hormones are atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), dendroaspis natriuretic peptide (DNP) and urodilatin, which play an important role in the homeostasis of body fluid volume. ANP and BNP have already been demonstrated to have diagnostic usefulness in a great number of studies, which have progressed from bench to bedside. This article summarizes existing data on ANP and related peptides in cardiovascular and other disorders, and outlines the potential clinical usefulness of these markers.

Clin Chem Lab Med 2007;45:1259–67.

Effects of the renal natriuretic peptide urodilatin (ularitide) in patients with decompensated chronic heart failure: a double-blind, placebo-controlled, ascending-dose trial

BACKGROUND

Urodilatin (ularitide), a natriuretic peptide, is produced within the kidneys. The aim of this study was to define the role of 24-hour intravenous infusions of urodilatin in the treatment of decompensated chronic heart failure (DHF).

METHODS

In this randomized, double-blind, ascending-dose safety study, 24 patients with DHF (cardiac index 1.91 +/- 0.34 L/min per square meter, pulmonary capillary wedge pressure 26 +/- 6 mm Hg, right atrial pressure 11 +/- 4 mm Hg) received urodilatin (7.5, 15, or 30 ng/(kg.min)) or placebo infusions over 24 hours.

RESULTS

Compared with baseline, urodilatin decreased pulmonary capillary wedge pressure by 10 mm Hg in the 15 ng/(kg.min) group (P < .05) and by 15 mm Hg in the 30 ng/(kg.min) group (P < .05) at 6 hours. In the same dose groups, right atrial pressure decreased, and dyspnea as reported by patients tended to improve. At 24 hours, 15 and 30 ng/(kg.min) urodilatin infusions decreased N-terminal-pro-brain natriuretic peptide levels by 40% and 45%, respectively, compared with baseline. Between 1 to 12 hours, plasma cyclic guanosine monophosphate levels at 15 and 30 ng/(kg.min) urodilatin were significantly higher than both placebo and the respective baseline after infusion start (P < .05 and .01). Among the different groups, there was no obvious difference regarding total number of patients with adverse events and total number of adverse events. During infusion, 3 transient asymptomatic hypotensions occurred in the urodilatin groups.

CONCLUSIONS

Our findings show that urodilatin may be a new agent for the therapy for DHF.

Role of natriuretic peptides in regulation of conduit artery distensibility

Arterial distensibility, assessed by the pulse-wave velocity (PWV), is an independent predictor of cardiovascular risk. We investigated whether natriuretic peptides, acting locally, modify conduit artery distensibility in vivo. All studies were conducted in anesthetized sheep ( n = 18) by using a validated ovine hindlimb model. In brief, the PWV was calculated, with the use of the foot-to-foot methodology, from two pressure waveforms recorded simultaneously with a high-fidelity dual pressure-sensing catheter placed in the common iliac artery. Drugs were infused either proximally, via the catheter to perfuse the segment of artery under study, or distally, via the sheath to control for any reflex changes in flow or sympathetic activation. First, the effects of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and c-type natriuretic peptide (CNP) were studied. Second, the role of endogenous ANP was investigated by infusing the natriuretic peptide receptor type A (NPRA)-selective receptor antagonist A71915. Third, A71915 was coinfused with ANP. Fourth, the NPRC-selective agonist cANF was infused. Infusion of CNP or des-[Gln18Ser19Gly20Leu21Gly22]-ANF-(4-23)-NH2 (cANF) had no effect on iliac PWV. However, infusion of ANP, and to a lesser degree BNP, resulted in a reduction in PWV (−9%; P < 0.01 and −6%; P < 0.05, respectively). A71915 increased iliac PWV from 2.97 ± 0.13 to 3.06 ± 0.13 m/s; P < 0.01. Coinfusion of A71915 with ANP completely abolished the effects of ANP ( P < 0.01). Importantly, ANP-BNP infusion via the sheath did not alter PWV. In conclusion, ANP, and to a lesser extent BNP, modify large artery distensibility via the NPRA receptor. Neither CNP nor cANF altered PWV, suggesting that the NPRB and NPRC receptors do not acutely influence distensibility in vivo.

Effects of exogenous and endogenous natriuretic peptides on forearm vascular function in chronic heart failure

OBJECTIVE

Natriuretic peptides (NPs) reduce central venous pressure in patients with chronic heart failure (cHF) despite attenuation of arterial, renal, and humoral effects. This suggests a preserved venodilator response. This study had 4 aims: to compare the venodilator effects of human NPs in patients with cHF; to assess the contribution of basal ANP and BNP levels to regulation of forearm vascular volume (FVV); to test the hypothesis that venous ANP responsiveness is preserved in cHF; and to assess the involvement of endothelial nitric oxide-synthase (eNOS) in NP-induced vascular effects.

METHODS AND RESULTS

Venous and arterial forearm vascular responses to incremental intra-arterial doses of ANP, Urodilatin, BNP, CNP, or the ANP receptor antagonist A71915 were studied in 53 patients and 11 controls. ANP receptor antagonism reduced FVV by 4.4%+/-1.2% (P<0.05). The forearm blood flow (FBF) response to ANP was significantly blunted in patients versus controls (P<0.01), whereas FVV increased similarly in both groups (maximum 14.7% and 13.4%, both P<0.001). The eNOS blockade reduced ANP-induced FBF changes in controls but not in patients (P<0.05), whereas similar reductions in FVV changes were seen in groups (both P<0.001).

CONCLUSIONS

In cHF venous, but not arterial, ANP responsiveness is preserved. Arterial endothelial dysfunction may contribute to NP resistance.

Usefulness of carperitide for the treatment of refractory heart failure due to severe acute myocardial infarction

Carperitide (synthetic atrial natriuretic peptide) is a newly developed drug for the treatment of heart failure. Although this drug has been used for various types of heart failure, it remains unknown whether it has additive effects on hemodynamic parameters or renal excretory function during intensive treatment for acute refractory heart failure. We have examined the cardiorenal and hormonal effects of carperitide (0.05-0.10 microg / min / kg) in 9 patients (mean age: 67+/-8 years) with severe heart failure complicated with acute myocardial infarction, in which a range of intensive treatments have already been started. Hemodynamic parameters were determined before and 4, 24 and 48 hours after initiation of carperitide. Pulmonary capillary wedge pressure (mean+/-SD) had decreased dramatically from 21+/-6 to 11+/-5 mmHg (p<0.01) 4 hours after the treatment without significant renal effects. Heart rate and systemic blood pressure were not significantly changed. These beneficial effects were maintained for at least 24 hours. Plasma aldosterone levels fell significantly in response to the drug (from 148+/-68 to 56+/-29 pg / ml; p<0.05). However, mean hourly urine output remained unchanged after carperitide. In conclusion, intravenous infusion of carperitide promptly and persistently reduces left ventricular filling pressure without diuresis, hypotension, reflex tachycardia, or neurohormonal activation in patients with refractory heart failure due to severe acute myocardial infarction.

New pharmacologic options for renal preservation

The understanding of the cause and pathophysiology of renal failure has guided the rational development of pharmacologic renoprotective strategies. Although traditionally anesthesiologists have focused on renal hemodynamic derangements, newer information suggests that cellular interactions amplify and perpetuate the insult. Consequently, the potential renoprotective armamentarium not only encompasses the more traditional vasoactive agents but also therapeutic approaches that may modify the cellular response to injury. Although few of these agents have reached the clinical arena, preliminary work suggests that this new approach to renal injury and protection may be promising.

Marked and prompt hemodynamic improvement by carperitide in refractory congestive heart failure due to dilated cardiomyopathy

A 16-year-old Japanese male diagnosed with congestive heart failure (CHF) due to dilated cardiomyopathy was treated by conventional intensive treatment such as intravenous infusion of diuretics, catecholamines, and phosphodiesterase inhibitors with vasodilators. However, he developed a low output syndrome with appearances of hyponatremia and hypochloremia. As a consequence, intravenous infusion of carperitide (synthetic atrial natriuretic peptide) was added to the therapy. Thereafter his symptoms and hemodynamic parameters promptly and dramatically improved without significant diuresis, and this amelioration persisted for more than 20 days without drug intolerance. This outcome suggests that use of carperitide may be a safe and efficacious means to reduce cardiac preload without hypotension and tachycardia in patients with refractory CHF in whom intensive treatment has already been performed.

Comparison of the short-term effects of candoxatril, an orally active neutral endopeptidase inhibitor, and frusemide in the treatment of patients with chronic heart failure

BACKGROUND

Candoxatril is a novel neutral endopeptidase inhibitor that increases plasma concentrations of atrial natriuretic factor and thereby produces natriuresis, diuresis, and vasorelaxation. This profile of action offers theoretical advantages over standard diuretic therapy in the treatment of patients with heart failure. The aims of the study were to compare the effects of candoxatril with those of frusemide in the treatment of patients with mild heart failure.

METHODS

Male patients with mild heart failure were randomly assigned to 9 days of therapy with 20 mg frusemide twice a day, 200 mg candoxatril twice a day, or 400 mg candoxatril twice a day (n = 10 per group) after a 14-day placebo washout phase. Systemic hemodynamic measurements, exercise tolerance, and urinary and plasma hormone concentrations were assessed during the placebo run-in and at the beginning and end of the double-blind therapy.

RESULTS

Frusemide and candoxatril caused similar diuresis and natriuresis. Candoxatril caused a slight decrease in systolic blood pressure and a dose-dependent increase in plasma and urinary concentrations of atrial natriuretic factor without elevating plasma renin activity. Frusemide reduced plasma concentrations of atrial natriuretic factor and increased plasma renin activity. Treadmill exercise capacity decreased 30 +/- 26 seconds after use of frusemide, compared with increases of 12 +/- 35 seconds after use of 200 mg candoxatril twice a day and 35 +/- 31 seconds after use of 400 mg candoxatril twice a day (P =.13; frusemide versus 400 mg candoxatril twice a day).

CONCLUSIONS

In the treatment of patients with mild heart failure, candoxatril has diuretic effects equivalent to those of 20 mg frusemide twice a day without the associated and potentially detrimental activation of the renin-angiotensin-aldosterone system. The trend for improved exercise capacity with candoxatril warrants further investigation.

Long-term administration of atrial natriuretic peptide in patients with acute heart failure

A short-term treatment of atrial natriuretic peptide (ANP), a circulating hormone of cardiac origin, is reported to improve cardiac performance in patients with chronic heart failure. However, clinical usefulness of long-term administration of ANP in patients with congestive heart failure has not been reported. We studied 36 patients with severe acute heart failure who resisted various therapy. Hemodynamic parameters were measured before and 48 h after initiating ANP infusion (n = 18) or normal saline (n = 18). Mean pulmonary capillary wedge pressure (23-->13 mm Hg), mean right atrial pressure (10-->5 mm Hg), systemic vascular resistance (2,169-->1,307 dyn x s x cm(-5)) and pulmonary vascular resistance (318-->136 dyn x s x cm(-5)) decreased significantly, whereas cardiac index (1.9-->2.6 L/min/m2) and urine volume (1,692-->2,560 ml/day) increased during long-term ANP infusion (before-->48 h). Moreover, in eight patients with long-term ANP infusion, these hemodynamic effects were maintained at 7 days after initiating ANP infusion. Vasodilating, pulmonary vasorelaxant, and diuretic activities of ANP are maintained without tolerance, and thus long-term ANP infusion is clinically useful in patients with severe acute heart failure.

Placebo-controlled comparison of candoxatril, an orally active neutral endopeptidase inhibitor, and captopril in patients with chronic heart failure

AIMS

To compare the effects on exercise capacity of the neutral endopeptidase inhibitor candoxatril, and the angiotensin converting enzyme inhibitor captopril, in patients with mild to moderate heart failure.

METHODS

In this multi-centre double-blind placebo controlled study, 60 patients with NYHA Class I-III heart failure were randomised to candoxatril 200 mg b.d. (n = 22), captopril 25-50 mg b.d. (n = 23) or placebo (n = 15). Treadmill exercise tests were carried out weekly during a 5-week single-blind placebo run-in phase until a stable baseline was achieved, and repeated at 4 weekly intervals during the 12-week double-blind treatment phase.

RESULTS

Nine patients withdrew from the study--four candoxatril and five captopril. The placebo-adjusted increase in exercise duration after 12 weeks was 56 s (95% CI, -26 to +137 s; P = 0.12) with candoxatril and 37 s (-43 to + 117 s; P = 0.29) with captopril.

CONCLUSIONS

Both candoxatril and captopril were well tolerated and treadmill exercise duration appeared to increase during 12 weeks of therapy but this did not achieve statistical significance. This study tentatively suggests that in patients with heart failure, neutral endopeptidase inhibition may provide similar symptomatic benefits to angiotensin converting enzyme inhibition.

Pulmonary oligemia in aortic valve disease

PURPOSE

To determine whether the severity of the radiographic appearance of oligemia correlates with the severity of cardiac dysfunction.

MATERIALS AND METHODS

Nine readers graded a set of 25 chest radiographs (15 cases of aortic valve disease [AVD], 10 control cases without AVD) for blood volume and ventricular size. Blood volume was graded on a scale of -3 (severe hyperemia) to 0 (normovolemia) to +3 (severe oligemia). Ventricular size was graded on a scale of 0 (normal) to 3 (massively enlarged). The oligemia and ventricular size grades were added to yield the radiographic severity index. Pulmonary capillary wedge pressure, pulmonary arterial pressure, stroke volume, and cardiac output were measured at the time of catheterization.

RESULTS

The five more experienced readers achieved good nonchance agreement (kappa = 0.48; P < .001). They were unanimous in scoring 12 cases as oligemic; variations occurred only in severity assessments. Oligemia was due to emphysema in one case and to AVD in 11. In oligemic cases, radiographic severity correlated significantly with wedge pressure (r = 0.93, P < .001) and pulmonary arterial pressure (r = 0.93, P < .002).

CONCLUSION

Many cases of AVD show oligemia. The severity of oligemia correlates well with hemodynamic abnormality. Oligemia may be caused by atrial-pulmonary-vascular reflex vasoconstriction, low right ventricular output, and possibly high levels of atrial natriuretic factor.

Atrial natriuretic peptide as a preload depressor in acute renal failure secondary to congestive heart failure

The present study was undertaken to verify the hypothesis that infusion of atrial natriuretic peptide (ANP) might lower preload and be beneficial in the treatment of pulmonary congestion even without a diuresis in patients with acute renal failure (ARF) secondary to severe congestive heart failure (CHF). We studied 22 patients with ARF secondary to CHF. The mean age of the patients (14 men and 8 women) was 72 years (range 36 to 85 years). Seven of the patients had dilated cardiomyopathy, ten had ischemic heart disease, and five had valvular heart disease. ANP was infused intravenously and the following data before and 1 hour after the start of ANP infusion were recorded; urinary output, systemic blood pressure (SBP), pulmonary blood pressure (PBP), right atrial pressure (RAP), cardiac index (CI), heart rate (HR), and arterial blood oxygen partial pressure. Diastolic PBP were employed as pulmonary capillary wedge pressure. Urinary output did not change. Mean SBP decreased from 92 to 85 mmHg (p < 0.05), and mean PBP decreased from 34 to 28 mmHg (p < 0.01). Mean RAP decreased from 11 to 9 mmHg (p < 0.01) and diastolic PBP decreased from 25 to 19 mmHg (p < 0.01). HR did not change significantly and CI increased 2.4 to 2.5 mi/min/m2 (p < 0.05). Arterial blood oxygen partial pressure increased significantly from 71 to 82 mmHg (p < 0.05). In conclusion, ANP decreased preload and improved arterial blood oxygen partial pressure, though diuretic response to ANP is attenuated in ARF secondary to CHE. Infusion of ANP will be very beneficial in cases in which dyspnea and pulmonary edema due to elevation of preload are the principal clinical problems.

Absence of vascular tolerance in conductance vessels after 48 hours of intravenous nitroglycerin in patients with coronary artery disease

OBJECTIVES

We examined whether reflex neurohormonal constrictor forces attenuate the vasodilator action of nitroglycerin on large peripheral conductance vessels.

BACKGROUND

Continuous nitroglycerin therapy is associated with the development of early tolerance with respect to its hemodynamic effects. It remains to be demonstrated whether vascular tolerance of large conductance vessels is an important contributory factor.

METHODS

Radial artery diameter and forearm blood flow velocity were measured before and 24 and 48 h after continuous intravenous nitroglycerin infusion (0.5 microgram/kg body weight per min) in 10 patients with coronary artery disease (mean age +/- SEM 59 +/- 4 years) by using a high resolution ultrasound device. Blood flow (ml/min) was calculated from mean blood flow velocity and cross-sectional area.

RESULTS

Increasing concentrations of nitroglycerin led to a dose-dependent increase in radial artery diameter (maximal +24 +/- 2%) and heart rate. Forearm vascular resistance and forearm blood flow were unchanged. After 24 and 48 h of treatment, additional nitroglycerin did not further increase radial artery diameter, indicating that the nitroglycerin-induced dilation of the radial artery was maintained and was still maximal. In addition, radial artery diameter measured before and after 48 h of nitroglycerin infusion and after withdrawal of nitroglycerin in five additional patients showed that, after withdrawal, arterial diameter returned to baseline values within 35 min. Plasma renin activity and serum aldosterone and vasopressin levels increased significantly at 24 and 48 h, accompanied by a decrease in hematocrit.

CONCLUSIONS

Continuous intravenous administration of nitroglycerin exerts a sustained vasodilator effect for 48 h in large conductance vessels. Neurohormonal activation and compensatory intravascular volume expansion do not attenuate the vasodilator effects of nitroglycerin on peripheral conductance vessels during the 1st 48 h of treatment.

Renal response to candoxatrilat in patients with heart failure

OBJECTIVES

Our primary objective was to compare the effects of three different doses of candoxatrilat with the effects of placebo on urinary volume in patients with moderately severe heart failure. The effects of candoxatrilat on urinary composition, neuroendocrine indexes and renal hemodynamic function were also studied.

BACKGROUND

Candoxatrilat, a neutral endopeptidase inhibitor, reduces degradation of atrial natriuretic peptide and provokes diuresis in patients with mild heart failure, but the renal effects have not been studied in patients with moderately severe heart failure in a placebo-controlled study.

METHODS

In a double-blind crossover trial, the effects of intravenous boluses of saline vehicle (placebo) and 50, 100 and 200 mg of candoxatrilat were compared on separate days in 12 patients with heart failure. Urinary output and composition were measured for 8 h. Renal blood flow and glomerular filtration rate were determined by radionuclide techniques. Blood was withdrawn for the measurement of hormones before and 3 h after dosing.

RESULTS

All doses of candoxatrilat increased urinary volume (e.g., [mean +/- SEM] 263 +/- 53 to 490 +/- 82 ml for saline solution and the 200-mg dose, respectively, p < 0.01) and sodium content (14 +/- 4 to 37 +/- 11 mmol, p < 0.001) in the 1st 4 h after dosing. Plasma atrial natriuretic peptide increased (140 +/- 26 to 279 +/- 37 pg/ml, p < 0.01), whereas aldosterone decreased (178 +/- 41 to 125 +/- 35 pg/ml, p < 0.01), and renin activity was unchanged (10 +/- 2 to 12 +/- 3 ng/ml per h).

CONCLUSIONS

Candoxatrilat given acutely causes diuresis, even in patients with moderately severe heart failure.

Efficacy of prolonged infusion of urodilatin [ANP-(95-126)] in patients with congestive heart failure

Urodilatin [ANP-95-126] is a new natriuretic peptide of renal origin not subjected to tolerance in experimental congestive heart failure (CHF). To evaluate its therapeutic potentials in CHF, we investigated the efficacy of a prolonged infusion of urodilatin (15 ng/kg/min for 10 hours) in 12 patients with CHF (New York Heart Association functional classes II and III) in a randomized, double-blind, placebo-controlled study. Urodilatin elevated plasma cyclic guanosine monophosphate (cGMP) concentrations and increased urinary cGMP excretion. Systolic blood pressure (121 +/- 9 mm Hg to 111 +/- 7 mm Hg) and central venous pressure (7.4 +/- 3.3 mm Hg to 5.2 +/- 3.4 mm Hg) decreased significantly, and diastolic blood pressure and heart rate remained unchanged. Urine flow (0.7 +/- 0.6 ml/min to 1.5 +/- .6 ml/min) and urinary sodium excretion (48 +/- 16 mumol/min to 180 +/- 97 mumol/min) were significantly increased. Plasma norepinephrine, renin, aldosterone, and vasopressin were unaltered. The substance was well tolerated. Thus prolonged infusion of urodilatin lowers preload and increases diuresis and natriuresis without neurohumoral activation or adverse side effects, demonstrating a profile of effects that may be beneficial in patients with CHF.

Severe hypotension and bradycardia after continuous intravenous infusion of urodilatin (ANP 95-126) in a patient with congestive heart failure

The effects of a continuous i.v. infusion of urodilatin at a dose of 30 ng kg-1 min-1 were studied in a patient with congestive heart failure. After 30 min, urodilatin had induced a marked stimulation of plasma cyclic GMP concentrations. In parallel haematocrit increased. No significant diuresis and no change of invasive haemodynamics was observed. After 2 h the patient developed a profuse perspiration. Eighty minutes later he suffered from dizziness due to hypotension (blood pressure 80/40 mmHg) and a sudden bradycardia (50 bpm). Urodilatin was discontinued and symptoms were relieved by bed tilt and rapid infusion of isotonic saline solution. Mechanisms contributing to these adverse effects may be fluid extravasation to the third space and sympathoinhibitory effects known to occur with natriuretic peptide infusion.

Apparent paradox of neurohumoral axis inhibition after body fluid volume depletion in patients with chronic congestive heart failure and water retention

BACKGROUND

Hypovolaemia stimulates the sympathoadrenal and renin systems and water retention. It has been proposed that in congestive heart failure reduction of cardiac output and any associated decrease in blood pressure cause underfilling of the arterial compartment, which promotes and perpetuates neurohumoral activation and the retention of fluid. This study examined whether an intravascular volume deficit accounts for patterns that largely exceed the limits of a homoeostatic response, which are sometimes seen in advanced congestive heart failure.

METHODS AND RESULTS

In 22 patients with congestive heart failure and water retention the body fluid mass was reduced by ultrafiltration and the neurohumoral reaction was monitored. A Diafilter, which was part of an external venous circuit was regulated to produce 500 ml/hour of ultrafiltrate (mean (SD) 3122 (1199) ml) until right atrial pressure was reduced to 50% of baseline. Haemodynamic variables, plasma renin activity, noradrenaline, and aldosterone were measured before and within 48 hours of ultrafiltration. After ultrafiltration, which produced a 20% reduction of plasma volume and a moderate decrease in cardiac output and blood pressure (consistent with a diminished degree of filling of the arterial compartment), there was an obvious decrease in noradrenaline, plasma renin activity, and aldosterone. In the next 48 hours plasma volume, cardiac output, and blood pressure recovered; the neurohumoral axis was depressed; and there was a striking enhancement of water and sodium excretion with resolution of the peripheral oedema and organ congestion. The neurohumoral changes and haemodynamic changes were not related. There were significant correlations between the neurohumoral changes and increase in urinary output and sodium excretion.

CONCLUSIONS

In advanced congestive heart failure arterial underfilling was not the main mechanism for activating the neurohumoral axis and retaining fluid. Because a decrease in circulating hormones was associated with reabsorption of extravascular fluid it is likely that hypoperfusion and/or congestion of organs, such as the kidney and lung, reduce the clearance of circulating noradrenaline and help to keep plasma concentrations of renin and aldosterone raised. A positive feedback loop between fluid retention and plasma hormone concentrations may be responsible for progression of congestive heart failure.

Atrial natriuretic peptide and its potential role in pharmacotherapy

Atrial natriuretic peptide (ANP) is a 28 amino-acid polypeptide secreted into the blood by atrial myocytes after atrial pressure and distension. Although its role in humans is not clear, it can produce a variety of physiologic effects including vasodilatation, natriuresis, and suppression of the renin-angiotensin-aldosterone axis. These actions are potentially useful in a variety of pathologic states such as hypertension and congestive heart failure, and diverse methods to augment the effects of ANP in these states have been devised. The results are exciting and, despite some problems, may lead to the pharmacologic use of enhancement of ANP actions in several clinical disorders.

Survival after myocardial infarction in the rat. Role of tissue angiotensin-converting enzyme inhibition

BACKGROUND

Chronic treatment with high doses of angiotensin-converting enzyme (ACE) inhibitors prolongs survival after myocardial infarction. Since the plasma renin-angiotensin system (RAS) is not consistently activated in the chronic phase after myocardial infarction, the beneficial effects of ACE inhibition have been attributed, in part, to inhibition of an activated tissue RAS. However, a relation between tissue ACE inhibition and long-term efficacy (ie, concerning left ventricular [LV] hypertrophy and survival) has not been established. The present study was designed to evaluate the impact of low-dose ACE inhibition (predominant inhibition of plasma ACE) and high-dose ACE inhibition associated with substantial tissue ACE inhibition) on reversal of LV hypertrophy and 1-year mortality after myocardial infarction in the rat.

METHODS AND RESULTS

Infarcted rats were randomized to placebo, low-dose lisinopril, or high-dose lisinopril (each, n = 80) and compared with sham-operated animals (n = 40). In a separate group of animals, tissue ACE activity was determined after 6 weeks of therapy, demonstrating that both regimens were effective with regard to both plasma and pulmonary ACE inhibition; however, only high-dose lisinopril inhibited renal ACE. Neither dose affected LV ACE activity and ACE mRNA levels as determined by competitive polymerase chain reaction, whereas LV ANF mRNA levels were significantly reduced by high-dose lisinopril. High-dose lisinopril reduced arterial blood pressure and normalized right ventricular and LV weight and resulted in a substantial reduction of 1-year mortality, whereas the low dose did not (1 year mortality: placebo, 56.3%; low dose, 53.3%; high dose, 22.9%, P < .0001 versus low dose and versus placebo).

CONCLUSIONS

Hemodynamically effective ACE inhibition is required for reduction of LV hypertrophy and long-term mortality after myocardial infarction in the rat. Sustained inhibition of renal ACE during long-term therapy may contribute to the beneficial effect of high-dose lisinopril. Low-dose lisinopril, although exerting sustained inhibition of the plasma ACE, does not improve survival after myocardial infarction.

Urodilatin: a new approach for the treatment of therapy-resistant acute renal failure after liver transplantation

A pilot study was performed in patients after liver transplantation (Ltx) to examine the effect of continuous intravenous urodilatin (URO, CDD/ANP-95-126)-infusion as an alternative therapy of acute renal failure (ARF) resistant to conventional therapy. Eight patients who developed ARF after liver transplantation and fulfilled requirements for haemodialysis/haemofiltration were treated. After URO infusion was started, renal function improved and all patients developed a strong diuresis and natriuresis within 2-4 h. The extracellular expansion due to sodium and water retention in anuric/oliguric ARF lead to an increased central venous pressure (CVP) and elevated blood pressure. During the URO infusion CVP declined and systolic, as well as diastolic, blood pressure were stable. In six patients where haemodialysis/haemofiltration could be avoided, serum creatinine (SC) and blood urea nitrogen (BUN) declined during URO treatment and creatinine clearance (CC) also improved significantly. Fluid and electrolyte disturbances changed promptly and normalized. This was in concordance with renal excretion of electrolytes. Two patients still required haemodialysis/haemofiltration. The six patients who did not require haemodialysis/haemofiltration after URO treatment normalized concerning their renal function and did well in a control period of 12 weeks. The study shows that continuous low dose URO infusion may present a new concept for treatment of postoperative acute renal failure resistant to conventional therapy.

Haemodynamic effects of atrial natriuretic peptide in hypoxic chronic obstructive pulmonary disease

BACKGROUND

Pulmonary artery pressure is elevated in patients with advanced chronic obstructive pulmonary disease (COPD). Release of atrial natriuretic peptide (ANP) is increased in pulmonary hypertension and this hormone may both selectively vasodilate pulmonary vessels and inhibit pulmonary vascular remodelling. The hypothesis that ANP has a physiological role in protection of the pulmonary circulation from pressure overload, and that it may be beneficial in patients with COPD, has been examined.

METHODS

Ten patients with hypoxic COPD were infused for 30 minute periods with saline followed by ANP at 0.4, 2, and 10 pmol/kg/min respectively via a pulmonary artery catheter whilst monitoring haemodynamics and oxygenation.

RESULTS

Levels of immunoreactive ANP (irANP) increased from a mean (SD) of 23 (15) pmol/l to a maximum of 94 (41) pmol/l. Neither systemic blood pressure, cardiac output nor total systemic vascular resistance showed any correlation with irANP levels. There were negative correlations between levels of ANP and mean pulmonary artery pressure which fell from 28.7 to 25.9 mm Hg, pulmonary artery wedge pressure which fell from 6.5 to 4.6 mmHg, and total pulmonary vascular resistance which fell from 489 to 428 dynes s cm-5. There was a small fall in PaCO2 from 6.2 to 5.9 kPa, whilst venous admixture and oxygen delivery both increased non-significantly.

CONCLUSIONS

At these pathophysiological concentrations there was evidence that ANP selectively reduced right ventricular afterload. These data support the hypotheses that increased plasma levels of ANP may be beneficial in hypoxic COPD, and that endogenous ANP may ameliorate pulmonary hypertension in humans.

Interaction of intravenous atrial natriuretic factor with furosemide in patients with heart failure

Furosemide is frequently administered intravenously to patients with chronic heart failure. However, use of diuretics may cause neuroendocrine activation and by itself may not consistently afford diuresis. Atrial natriuretic factor (ANF) in pharmacologic doses is a vasodilator and has favorable neuroendocrinologic effects in patients with congestive heart failure. To examine whether exogenous ANF might enhance the effects of acute furosemide injection, we studied 14 patients with chronic stable heart failure and measured the effects of the combination of ANF and furosemide on hemodynamics, neuroendocrine activation, and urine output. Eight patients were randomly assigned to receive placebo plus furosemide (1.3 mg/kg intravenously). Six patients received ANF (2 micrograms/kg intravenously) plus furosemide at the same dose in a double-blind manner. The group receiving placebo plus furosemide exhibited a slight increase in mean arterial pressure (92 to 96 mm Hg; p < 0.03), systemic vascular resistance (1989 to 2271 dynes.sec.cm-5; p = 0.0007), and pulmonary capillary wedge pressure (22 to 24 mm Hg; p < 0.04) from baseline to 10 minutes. The group receiving ANF plus furosemide exhibited no change in mean arterial pressure and systemic vascular resistance from baseline to 10 minutes. Pulmonary capillary wedge pressure and mean pulmonary pressure were unchanged. In the group receiving placebo plus furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)

Concurrent neutral endopeptidase and ACE inhibition in experimental heart failure: renal and hormonal effects

Neutral endopeptidase (NEP) inhibitors have been shown to strengthen the effects of endogenous atrial natriuretic peptide (ANP). It has been well documented that angiotensin I-converting enzyme (ACE) inhibitors act beneficially in chronic congestive heart failure (CHF). In the present study, renal and hormonal effects of SCH 34826, an orally active NEP inhibitor, were studied in a coronary-ligation model of experimental CHF in the rat. The effects were compared to those of captopril. The drugs were also administered in combination. In anaesthetized rats with CHF, SCH 34826 (90 mg kg-1 sc) elevated plasma ANP from 382 +/- 85 to 658 +/- 120 ng l-1 compared with vehicle (p = 0.002). In sham-operated control rats, plasma ANP also increased slightly from 52 +/- 6 to 70 +/- 9 ng l-1 (p = 0.05). Plasma renin activity did not change in either group. When given orally for 36 h (90 mg kg-1 b.i.d.), SCH 34826 enhanced natriuresis in controls but not in rats with CHF. Captopril (0.2 mg ml-1 in drinking water) enhanced natriuresis in CHF rats and both natriuresis and kaliuresis in controls. When SCH 34826 and captopril were combined, natriuresis was potentiated in control rats as compared with captopril alone; in rats with CHF, however, a brisk kaliuresis was seen. The excretion of cyclic guanosine monophosphate was enhanced in CHF rats by 52% during treatment with SCH 34826 but not with captopril or combination of the two drugs. Moreover, captopril suppressed aldosterone excretion both in CHF rats and controls when administered alone but not when combined with SCH 34826.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma cyclic guanosine 3'-5' monophosphate concentrations and low vascular resistance in human septic shock

OBJECTIVE

To investigate the increase in plasma cyclic GMP (cGMP) concentrations in humans with hyperkinetic septic shock (SS) and to evaluate its relationship to low systemic vascular resistance (SVR).

DESIGN

Prospective clinical investigation.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

22 patients with documented SS requiring hemodynamic resuscitation, respiratory support and--in some cases--hemodialysis.

MEASUREMENTS AND RESULTS

Hemodynamic data were recorded at admission time and then twice a-day during the following 72 h. We simultaneously measured cyclic GMP, atrial natriuretic peptides (ANP), creatininemia and platelet counts. At admission time, higher plasma cGMP concentrations were observed in patients with SS (11.84 +/- 1.52 pmol.ml-1) than in healthy controls (1.77 +/- 0.18 pmol.ml-1, p < 0.0001), in septicemia patients without circulatory failure (3.28 +/- 0.36 pmol.ml-1, p < 0.005) or in patients with hyperkinetic non-septic shock (3.6 +/- 0.7 pmol.ml-1, p < 0.02). In contrast, there was no significant difference between patients with SS and controls with anuria from non-septic origin. Also ANP concentrations were higher in patients with SS than in others. In addition, cGMP levels correlated negatively with SVR during the first 48 h of the study, and positively with creatininemia later when renal function worsened. However, they did not correlate significantly with ANP.

CONCLUSION

These data demonstrate that a significant increase in plasma cGMP concentrations occurs during human SS and that it correlates with the decline in peripheral vascular resistance in the absence, but not in the presence, of severe renal failure. Furthermore, the increase in cGMP levels cannot be ascribed solely to enhanced ANP-induced particulate guanylyl cyclase activity. Thus, our results suggest the occurrence of another endogenous source of cGMP during hyperkinetic SS.

Neurohormonal inhibition and hemodynamic unloading during prolonged inhibition of ANF degradation in patients with severe chronic heart failure

BACKGROUND

The purpose of this study was to investigate the therapeutic potential of prolonged inhibition of atrial natriuretic factor (ANF) degradation in patients with severe chronic heart failure.

METHODS AND RESULTS

The effects of repeated doses of the endopeptidase inhibitor candoxatrilat (150 mg i.v.) were examined over a 24-hour period in patients with severe chronic heart failure (New York Heart Association class III-IV). Plasma alpha-hANF(99-126) was elevated at baseline (235 +/- 59 pg/ml), increased 2.5-fold at 2 hours after the first dose, and remained significantly elevated throughout the 24-hour protocol. In contrast, pro-hANF(31-67) decreased from 3,151 +/- 616 to 2,072 +/- 362 pg/ml (p less than 0.05). Cardiac index (CI) increased only transiently after the first dose of candoxatrilat (CI, 2.11 +/- 0.2 to 2.67 +/- 0.28 l/min/m2, p less than 0.05). Sodium excretion increased sixfold (p less than 0.05) 2 hours after the first dose of candoxatrilat and remained significantly elevated throughout the protocol. Degree of natriuresis and diuresis in response to candoxatrilat was closely related to baseline cardiac output. Glomerular filtration rate and volume excretion did not change significantly. Pulmonary capillary wedge pressure fell from 23 +/- 3 to 18 +/- 3 mm Hg (p less than 0.05) and remained below baseline throughout the 24 hours. Arterial pressure, heart rate, and total peripheral resistance did not change significantly during the 24-hour period. Urinary cGMP excretion increased fivefold (p less than 0.05), whereas urinary ANF immunoreactivity and plasma cGMP levels remained unchanged. Excretion of prostacyclin metabolite 6-keto-PGF-1 alpha increased 3.3-fold (p less than 0.05). Plasma norepinephrine and epinephrine levels decreased significantly after candoxatrilat and remained suppressed over the 24-hour period. There was also a transient reduction in plasma vasopressin, aldosterone levels, and plasma renin activity. Hematocrit, total protein content, and plasma albumin concentrations did not change, indicating that no fluid shift into the extravascular space had occurred.

CONCLUSIONS

1) The inhibition of ANF degradation causes sustained drop in left and right atrial pressures that appears to be mediated by an inhibition of neurohumoral activity; 2) concomitant inhibition of bradykinin breakdown (which in turn stimulates renal prostacyclin synthesis) contributes to natriuresis; 3) the close correlation between renal response and baseline cardiac index indicates that an inadequate renal perfusion secondary to low cardiac output diminishes the efficacy of this treatment modality. This spectrum of action would be advantageous for a first-line diuretic agent early in the course of disease rather than in patients with advanced chronic heart failure.

Maintenance of forearm vasodilator action of atrial natriuretic factor in congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Infusions of atrial natriuretic factor (ANF) are frequently associated with attenuated natriuretic and diuretic responses in patients with congestive heart failure. However, ANF infusions result in systemic vasodilation, suggesting that end organ responsiveness to ANF may not be uniformly decreased. To determine if the vasodilator effects of ANF were altered in heart failure, strain-gauge plethysmography was utilized to measure forearm blood flow responses to the intraarterial infusion of ANF using a dose range that was low enough to avoid systemic effects. In 9 control subjects, ANF infusions of 0.5, 1.0, 2.0 and 4.0 micrograms/min/100 ml forearm volume significantly increased forearm blood flow from 3.21 +/- 1.71 to 5.69 +/- 3.14, 6.20 +/- 2.57, 6.64 +/- 2.53 and 6.97 +/- 2.49 ml/min/100 ml forearm volume, respectively (all p less than 0.01). In 7 patients with heart failure, ANF infusion significantly increased forearm blood flow from 2.19 +/- 0.98 to 3.18 +/- 1.70, 3.76 +/- 2.0 and 4.42 +/- 2.80 ml/min/100 ml forearm volume for the 0.5, 1.0 and 2.0 micrograms doses, respectively (all p less than 0.05). By analysis of variance, the forearm blood flow responses pooled over all doses were not significantly different between the 2 groups. At the 2.0 micrograms dose, the peak increase in forearm blood flow in normal subjects represented a 107% increase over baseline compared with a 102% increase in patients with heart failure. In summary, these data demonstrate that intraarterial administration of ANF in patients with heart failure resulted in dose-related increases in forearm blood flow. The responses were not significantly different from normal subjects expressed both as an absolute response and as a percent increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral adaptations in congestive heart failure: a review

In congestive heart failure, peripheral adaptive mechanisms play a significant and largely underestimated role. In acute heart failure, sympathetic-mediated peripheral vasoconstriction together with chronotropic and inotropic actions serves to maintain perfusion pressure and blood supply to the vital organs. In chronic heart failure, activation of the renin-angiotensin system increases peripheral vascular resistance and arterial tone and decreases arterial compliance and vasodilator capacity. Endothelium-mediated, flow-dependent vasodilation is reduced as a consequence of reduced blood flow. Deconditioning renders the blood vessels incapable of dilating in response to increased flow. Simultaneously, reduced blood flow and inactivity are induced by deconditioning, with functional and structural consequences within the skeletal muscle. Exercise performance is limited by reduced overall blood flow, reduced conductance of the feeding arteries, elevated tone of the resistance vessels, reduced vasodilator capacity, impaired dissipation of heat from the working muscle, and functional and structural changes of the skeletal muscle due to underperfusion and inactivity. The adaptive mechanisms operate at different time scales. Under therapeutic intervention, their reversibility also follows different time constants. Restoration of the vasodilator capacity of the large arteries and of the abnormalities of skeletal muscle in heart failure requires time. Vasodilation with reduced pre- and/or afterload will retard progression of the superimposed ventricular dilation and hypertrophy, and therefore retard the progress of the disease. However, restoration of the peripheral blood flow and of organ function will require time. Restoration of the vascular compliance and of the full amplitude of adaptive flow-dependent vasodilation in the large arteries requires weeks or months. Similarly, restoration of functionally and morphologically altered skeletal muscle can be expected to be reversible over a longer time period.