Angiotensin converting enzyme inhibition restores cardiac and hormonal responses to volume overload in patients with dilated cardiomyopathy and mild heart failure

Oryeongsan (Wulingsan) ameliorates impaired ANP secretion of atria from spontaneously hypertensive rats

Oryeongsan (ORS), a herbal medicine formula, has long been used for the treatment of impaired body water balance in Asian countries. Recently, it was shown that ORS administration modulates the renin-angiotensin system (RAS). Purpose of the present study was to determine characteristics of atrial ANP secretion and effects of ORS on the secretion in the atria from spontaneously hypertensive rats (SHR). Normotensive WKY groups (WKY-V, WKY-ORS, WKY-LOS) and hypertensive SHR groups (SHR-V, SHR-ORS, SHR-LOS) treated with vehicle, ORS, and losartan as a positive control group, respectively, were used. Experiments were performed in perfused beating atria (1.3 Hz) allowing atrial distension, acetylcholine (ACh) stimulation, and serial collection of atrial perfusates. The secreted ANP concentration was measured using radioimmunoassay. Interstitial fluid (ISF) translocation was measured using [³H]inulin clearance. Stepwise increase in atrial distension by 1.1, 2.0, and 2.7 cmH₂O above basal distension further increased ANP secretion proportionally in the atria from WKY-V, but the response was significantly suppressed in the atria from SHR-V. Cardiomyocyte ANP release, the first step of atrial ANP secretion, was suppressed in the atria from SHR-V compared to those from WKY-V (-8.02 ± 2.86, -15.86 ± 2.27, and -20.09 ± 3.62%; n = 8, for SHR-V vs. 8.59 ± 2.81, 15.65 ± 7.14, and 38.12 ± 8.28%; n = 8, for WKY-V; p < 0.001 for all stepwise distension, respectively). Chronic treatment with ORS reversed the suppressed ANP release in atria from SHR-ORS group (6.76 ± 3.92, 9.12 ± 2.85, and 28.79 ± 1.79% for SHR-ORS; n = 5 vs. SHR-V; n = 8; p = 0.01, p < 0.001, p < 0.001, respectively). The effects of ORS were comparable to those of losartan. Trans-endocardial translocation of ISF, the second step of atrial ANP secretion was similar in the atria from the hypertensive SHR-V and normotensive WKY-V. ACh-induced ANP secretion and cardiomyocyte ANP release were also suppressed in the atria from SHR-V compared to WKY-V and ORS reversed the suppression. These findings were accompanied with accentuation of the AT₁ receptor expression and suppression of the AT₂/Mas receptor, M₂ mACh receptor and GIRK4, a molecular component of K_ACh channel, expression in the atria from SHR-V. Further, treatment with ORS or losartan reversed the expressions in the groups of SHR-ORS and SHR-LOS. These results show that ANP secretion is suppressed in the atria from SHR in association with accentuation of AT₁ receptor and suppression of AT₂/Mas receptor and K_ACh channel expression. Treatment with ORS ameliorates impaired ANP secretion through improving cardiomyocyte ANP release with modulation of the cardiac RAS and muscarinic signaling. These findings provide experimental evidence which supports the effect of ORS on the regulation of atrial ANP secretion in the atria from SHR.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin-aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction (LVEF); a review of the evidence is required to determine whether these treatments are beneficial for people with heart failure with preserved ejection fraction (HFpEF).

OBJECTIVES

To assess the effects of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with HFpEF.

SEARCH METHODS

We updated searches of CENTRAL, MEDLINE, Embase, and one clinical trial register on 14 May 2020 to identify eligible studies, with no language or date restrictions. We checked references from trial reports and review articles for additional studies.  SELECTION CRITERIA: We included randomised controlled trials with a parallel group design, enrolling adults with HFpEF, defined by LVEF greater than 40%.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 41 randomised controlled trials (231 reports), totalling 23,492 participants across all comparisons. The risk of bias was frequently unclear and only five studies had a low risk of bias in all domains. Beta-blockers (BBs) We included 10 studies (3087 participants) investigating BBs. Five studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 30 years to 81 years. A possible reduction in cardiovascular mortality was observed (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.62 to 0.99; number needed to treat for an additional benefit (NNTB) 25; 1046 participants; three studies), however, the certainty of evidence was low. There may be little to no effect on all-cause mortality (RR 0.82, 95% CI 0.67 to 1.00; 1105 participants; four studies; low-certainty evidence). The effects on heart failure hospitalisation, hyperkalaemia, and quality of life remain uncertain. Mineralocorticoid receptor antagonists (MRAs) We included 13 studies (4459 participants) investigating MRA. Eight studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 54.5 to 80 years. Pooled analysis indicated that MRA treatment probably reduces heart failure hospitalisation (RR 0.82, 95% CI 0.69 to 0.98; NNTB = 41; 3714 participants; three studies; moderate-certainty evidence). However, MRA treatment probably has little or no effect on all-cause mortality (RR 0.91, 95% CI 0.78 to 1.06; 4207 participants; five studies; moderate-certainty evidence) and cardiovascular mortality (RR 0.90, 95% CI 0.74 to 1.11; 4070 participants; three studies; moderate-certainty evidence). MRA treatment may have little or no effect on quality of life measures (mean difference (MD) 0.84, 95% CI -2.30 to 3.98; 511 participants; three studies; low-certainty evidence). MRA treatment was associated with a higher risk of hyperkalaemia (RR 2.11, 95% CI 1.77 to 2.51; number needed to treat for an additional harmful outcome (NNTH) = 11; 4291 participants; six studies; high-certainty evidence). Angiotensin-converting enzyme inhibitors (ACEIs) We included eight studies (2061 participants) investigating ACEIs. Three studies used a placebo comparator and in five the comparator was usual care. The mean age of participants ranged from 70 to 82 years. Pooled analyses with moderate-certainty evidence suggest that ACEI treatment likely has little or no effect on cardiovascular mortality (RR 0.93, 95% CI 0.61 to 1.42; 945 participants; two studies), all-cause mortality (RR 1.04, 95% CI 0.75 to 1.45; 1187 participants; five studies) and heart failure hospitalisation (RR 0.86, 95% CI 0.64 to 1.15; 1019 participants; three studies), and may result in little or no effect on the quality of life (MD -0.09, 95% CI -3.66 to 3.48; 154 participants; two studies; low-certainty evidence). The effects on hyperkalaemia remain uncertain. Angiotensin receptor blockers (ARBs) Eight studies (8755 participants) investigating ARBs were included. Five studies used a placebo comparator and in three the comparator was usual care. The mean age of participants ranged from 61 to 75 years. Pooled analyses with high certainty of evidence suggest that ARB treatment has little or no effect on cardiovascular mortality (RR 1.02, 95% 0.90 to 1.14; 7254 participants; three studies), all-cause mortality (RR 1.01, 95% CI 0.92 to 1.11; 7964 participants; four studies), heart failure hospitalisation (RR 0.92, 95% CI 0.83 to 1.02; 7254 participants; three studies), and quality of life (MD 0.41, 95% CI -0.86 to 1.67; 3117 participants; three studies). ARB was associated with a higher risk of hyperkalaemia (RR 1.88, 95% CI 1.07 to 3.33; 7148 participants; two studies; high-certainty evidence). Angiotensin receptor neprilysin inhibitors (ARNIs) Three studies (7702 participants) investigating ARNIs were included. Two studies used ARBs as the comparator and one used standardised medical therapy, based on participants' established treatments at enrolment. The mean age of participants ranged from 71 to 73 years. Results suggest that ARNIs may have little or no effect on cardiovascular mortality (RR 0.96, 95% CI 0.79 to 1.15; 4796 participants; one study; moderate-certainty evidence), all-cause mortality (RR 0.97, 95% CI 0.84 to 1.11; 7663 participants; three studies; high-certainty evidence), or quality of life (high-certainty evidence). However, ARNI treatment may result in a slight reduction in heart failure hospitalisation, compared to usual care (RR 0.89, 95% CI 0.80 to 1.00; 7362 participants; two studies; moderate-certainty evidence). ARNI treatment was associated with a reduced risk of hyperkalaemia compared with valsartan (RR 0.88, 95% CI 0.77 to 1.01; 5054 participants; two studies; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

There is evidence that MRA and ARNI treatment in HFpEF probably reduces heart failure hospitalisation but probably has little or no effect on cardiovascular mortality and quality of life. BB treatment may reduce the risk of cardiovascular mortality, however, further trials are needed. The current evidence for BBs, ACEIs, and ARBs is limited and does not support their use in HFpEF in the absence of an alternative indication. Although MRAs and ARNIs are probably effective at reducing the risk of heart failure hospitalisation, the treatment effect sizes are modest. There is a need for improved approaches to patient stratification to identify the subgroup of patients who are most likely to benefit from MRAs and ARNIs, as well as for an improved understanding of disease biology, and for new therapeutic approaches.

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system for chronic heart failure with preserved ejection fraction

BACKGROUND

Beta-blockers and inhibitors of the renin-angiotensin aldosterone system improve survival and reduce morbidity in people with heart failure with reduced left ventricular ejection fraction. There is uncertainty whether these treatments are beneficial for people with heart failure with preserved ejection fraction and a comprehensive review of the evidence is required.

OBJECTIVES

To assess the effects of beta-blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, angiotensin receptor neprilysin inhibitors, and mineralocorticoid receptor antagonists in people with heart failure with preserved ejection fraction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and two clinical trial registries on 25 July 2017 to identify eligible studies. Reference lists from primary studies and review articles were checked for additional studies. There were no language or date restrictions.

SELECTION CRITERIA

We included randomised controlled trials with a parallel group design enrolling adult participants with heart failure with preserved ejection fraction, defined by a left ventricular ejection fraction of greater than 40 percent.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and extracted data. The outcomes assessed included cardiovascular mortality, heart failure hospitalisation, hyperkalaemia, all-cause mortality and quality of life. Risk ratios (RR) and, where possible, hazard ratios (HR) were calculated for dichotomous outcomes. For continuous data, mean difference (MD) or standardised mean difference (SMD) were calculated. We contacted trialists where neccessary to obtain missing data.

MAIN RESULTS

37 randomised controlled trials (207 reports) were included across all comparisons with a total of 18,311 participants.Ten studies (3087 participants) investigating beta-blockers (BB) were included. A pooled analysis indicated a reduction in cardiovascular mortality (15% of participants in the intervention arm versus 19% in the control arm; RR 0.78; 95% confidence interval (CI) 0.62 to 0.99; number needed to treat to benefit (NNTB) 25; 1046 participants; 3 studies). However, the quality of evidence was low and no effect on cardiovascular mortality was observed when the analysis was limited to studies with a low risk of bias (RR 0.81; 95% CI 0.50 to 1.29; 643 participants; 1 study). There was no effect on all-cause mortality, heart failure hospitalisation or quality of life measures, however there is uncertainty about these effects given the limited evidence available.12 studies (4408 participants) investigating mineralocorticoid receptor antagonists (MRA) were included with the quality of evidence assessed as moderate. MRA treatment reduced heart failure hospitalisation (11% of participants in the intervention arm versus 14% in the control arm; RR 0.82; 95% CI 0.69 to 0.98; NNTB 41; 3714 participants; 3 studies; moderate-quality evidence) however, little or no effect on all-cause and cardiovascular mortality and quality of life measures was observed. MRA treatment was associated with a greater risk of hyperkalaemia (16% of participants in the intervention group versus 8% in the control group; RR 2.11; 95% CI 1.77 to 2.51; 4291 participants; 6 studies; high-quality evidence).Eight studies (2061 participants) investigating angiotensin converting enzyme inhibitors (ACEI) were included with the overall quality of evidence assessed as moderate. The evidence suggested that ACEI treatment likely has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. Data for the effect of ACEI on hyperkalaemia were only available from one of the included studies.Eight studies (8755 participants) investigating angiotensin receptor blockers (ARB) were included with the overall quality of evidence assessed as high. The evidence suggested that treatment with ARB has little or no effect on cardiovascular mortality, all-cause mortality, heart failure hospitalisation, or quality of life. ARB was associated with an increased risk of hyperkalaemia (0.9% of participants in the intervention group versus 0.5% in the control group; RR 1.88; 95% CI 1.07 to 3.33; 7148 participants; 2 studies; high-quality evidence).We identified a single ongoing placebo-controlled study investigating the effect of angiotensin receptor neprilysin inhibitors (ARNI) in people with heart failure with preserved ejection fraction.

AUTHORS' CONCLUSIONS

There is evidence that MRA treatment reduces heart failure hospitalisation in heart failure with preserverd ejection fraction, however the effects on mortality related outcomes and quality of life remain unclear. The available evidence for beta-blockers, ACEI, ARB and ARNI is limited and it remains uncertain whether these treatments have a role in the treatment of HFpEF in the absence of an alternative indication for their use. This comprehensive review highlights a persistent gap in the evidence that is currently being addressed through several large ongoing clinical trials.

The natriuretic peptides system in the pathophysiology of heart failure: from molecular basis to treatment

After its discovery in the early 1980s, the natriuretic peptide (NP) system has been extensively characterized and its potential influence in the development and progression of heart failure (HF) has been investigated. HF is a syndrome characterized by the activation of different neurohormonal systems, predominantly the renin-angiotensin (Ang)-aldosterone system (RAAS) and the sympathetic nervous system (SNS), but also the NP system. Pharmacological interventions have been developed to counteract the neuroendocrine dysregulation, through the down modulation of RAAS with ACE (Ang-converting enzyme) inhibitors, ARBs (Ang receptor blockers) and mineralcorticoid antagonists and of SNS with β-blockers. In the last years, growing attention has been paid to the NP system. In the present review, we have summarized the current knowledge on the NP system, focusing on its role in HF and we provide an overview of the pharmacological attempts to modulate NP in HF: from the negative results of the study with neprilysin (NEP) inhibitors, alone or associated with an ACE inhibitor and vasopeptidase inhibitors, to the most recently and extremely encouraging results obtained with the new pharmacological class of Ang receptor and NEP inhibitor, currently defined ARNI (Ang receptor NEP inhibitor). Indeed, this new class of drugs to manage HF, supported by the recent results and a vast clinical development programme, may prompt a conceptual shift in the treatment of HF, moving from the inhibition of RAAS and SNS to a more integrated target to rebalance neurohormonal dysregulation in HF.

Chronic subcutaneous brain natriuretic peptide therapy in asymptomatic systolic heart failure

AIMS

We have previously reported that asymptomatic systolic heart failure (HF) is characterized by an impaired renal response to volume expansion due to lack of activation of urinary cGMP which is corrected by subcutaneous (SQ) BNP. In the current study, we sought to define the cardiorenal response to intravascular volume expansion after 12 weeks of SQ BNP therapy.

METHODS AND RESULTS

We utilized a double-blinded, placebo-controlled study to compare 12 weeks of twice-daily SQ BNP 10 µg/kg (n = 22) or placebo (n = 12) in asymptomatic systolic HF. Subjects underwent two study visits: baseline and after 12 weeks of therapy. At each study visit, echocardiography, renal, and neurohumoral assessments were performed before and after intravascular volume expansion. The primary endpoint was change in urinary sodium excretion in response to volume expansion at 12 weeks, and we observed a greater increase in urinary sodium excretion [166 (77, 290) vs. 15 (-39, 72) mEq/min; P = 0.02] with SQ BNP treatment vs. placebo. Secondary endpoints included change in urine flow and glomerular filtration rate (GFR) in response to volume expansion at 12 weeks. We observed a significant increase in urine flow (P < 0.01) and trend for differential response in GFR (P = 0.08) with SQ BNP treatment vs. placebo.

CONCLUSION

Among patients with asymptomatic systolic HF, twice-daily SQ BNP therapy improved the cardiorenal response to volume expansion at 12-week follow-up. Further studies are warranted to determine if these beneficial physiological observations with chronic natriuretic peptide administration translate into a delay in the progression to symptomatic HF.

Repeated assessment of physical biomeasures or blood biomarkers for the definition of volume status and cardiac loading in LVSD

The application of biomarker technology can be usefully implemented in areas where current techniques are inadequate and where a clinical issue, which affects outcome, can be defined. The definition of the loading status of the heart where there is pre-existent impairment of contractile function is a key target. Heart failure is a complex clinical presentation with many varied etiologies, but at the essence of its successful management is the reliable definition of cardiac volume loading. Traditional and many current technological measures are applied to define this relationship, yet their accuracy and performance in individual patients is either basically inadequate or poorly understood and applied. There is a wide range of both physical measurements and blood biomarkers that can be considered to better define this key issue in patients with ventricular systolic impairment. Their performance is considered in detail in this review.

Evaluation of atrial and brain natriuretic polypeptides in association with angiotensin-converting enzyme gene polymorphism in Japanese non-diabetic hemodialysis patients

OBJECTIVE

Insertion (I)/deletion (D) polymorphisms in the angiotensin-converting enzyme (ACE) gene have the potential to serve as a marker for an increased risk of cardiovascular events. Increased plasma levels of human atrial natriuretic polypeptide (ANP) and brain natriuretic polypeptide (BNP) are important indexes of cardiac function. The aim of this study was to examine possible relationships between I/D polymorphisms and the myocardial release of ANP and BNP in Japanese hemodialysis (HD) patients (n=131).

MATERIAL AND METHODS

We studied 131 non-diabetic hemodialysis patients. The genotype of ACE gene was determined by polymerase chain reaction with a set of specific timers. ANP and BNP levels were measured before HD.

RESULTS

The plasma levels of ANP and BNP were significantly lower in the DD genotype group compared to those in the II group. Corresponding levels in the ID genotype group were intermediate between those in the DD and II groups. ACE polymorphism was associated with neither ejection fraction nor left ventricular mass/height index (LVMI), as evidenced by echocardiographic findings (n=107). Plasma levels of ANP were significantly correlated with left atrial diameter (LAD) in patients as a whole, but this correlation was only observed in the II genotype group, and not in the DD or ID groups. Plasma levels of BNP were significantly correlated with LAD, left ventricular end systolic diameter and LVMI in patients as a whole, but these correlations were seen only in the II genotype group.

CONCLUSION

The results suggest that the plasma levels of these natriuretic peptides should be evaluated on the basis of ACE polymorphism for assessing cardiac diseases due to volume overload in Japanese HD patients.

Captopril-furosemide survival study in experimental heart failure

The strategy of diuretic drug administration remains to be defined in heart failure as experimental and clinical evidence have clearly established the benefit of neurohormonal blockade. The impact of addition of diuretic treatment to angiotensin-converting enzyme inhibition on survival remains to be demonstrated. The objectives of the study were to evaluate cardiovascular and renal effects of addition of diuretic treatment to captopril (2 g/L, in drinking water), on survival, on the experimental model of heart failure. Rats were followed for 10 months after coronary ligation. Echocardiographic, hemodynamic, morphometry and renal function investigations were then performed on surviving rats. Survival (from 34 to 61%), diuresis and natriuresis were significantly improved compared to control group only in animals treated with a combination of captopril + furosemide. In treated group: cardiac dimensions were reduced with left ventricular fractional shortening significantly increased in combination group (from 22.4 to 28%); captopril + furosemide animals had highest heart rate and lowest systolic and diastolic blood pressures; body and heart weight were reduced, but kidney weight was significantly increased with furosemide (1.7 g in control vs. 2 g in capto + furo); plasma renin activity and angiotensin 1 were greatly increased, and moderately stimulated in control. In conclusion, this combination of drugs significantly improved cardiac remodeling and survival of animals, increased diuresis and natriuresis despite stimulation of plasma renin activity and kidney hypertrophy.

Hypertension and Heart Failure: Role of Neurohormonal Mechanisms

Hypertension represents the most common associated cause of heart failure, and it is frequently involved in the pathogenesis of left ventricular dysfunction and its progression towards congestive heart failure. A common pathophysiological link of hypertension to heart failure is represented by the abnormalities of the neurohormonal profile and its impact on cardiac function, systemic hemodynamics and salt/water balance. This article synthetically reviews this aspect together with a specific analysis of the significance of measurements of neurohormones for diagnosis and prognostic stratification in heart failure.

Rat corin gene: molecular cloning and reduced expression in experimental heart failure

Stored cardiac pro-atrial natriuretic peptide (pro-ANP) is converted to ANP and released upon stretch from the atria into the circulation. Corin is a serin protease with pro-ANP-converting properties and may be the rate-limiting enzyme in ANP release. This study was aimed to clone and sequence corin in the rat and to analyze corin mRNA expression in heart failure when ANP release upon stretch is blunted. Full-length cDNA of rat corin was obtained from atrial RNA by RT-PCR and sequenced. Tissue distribution as well as regulation of corin mRNA expression in the atria were determined by RT-PCR and RNase protection assay. Heart failure was induced by an infrarenal aortocaval shunt. Stretch was applied to the left atrium in a working heart modus, and ANP was measured in the perfusates. The sequence of rat corin cDNA was found to be 93.6% homologous to mouse corin cDNA. Corin mRNA was expressed almost exclusively in the heart with highest concentrations in both atria. The aortocaval shunt led to cardiac hypertrophy and heart failure. Stretch-induced ANP release was blunted in shunt animals (control 1,195 ± 197 fmol·min−1·g−1; shunt: 639 ± 99 fmol·min−1·g−1, P < 0.05). Corin mRNA expression was decreased in both atria in shunt animals [right atrium: control 0.638 ± 0.004 arbitrary units (AU), shunt 0.566 ± 0.014 AU, P < 0.001; left atrium: control 0.564 ± 0.009 AU, shunt 0.464 ± 0.009 AU, P < 0.001]. Downregulation of atrial corin mRNA expression may be a novel mechanism for the blunted ANP release in heart failure.

Losartan treatment and left ventricular filling during volume loading in patients with dilated cardiomyopathy

BACKGROUND

Patients with mild heart failure show a reduction in preload reserve mechanism during volume expansion. At this time, the effects of volume expansion on left ventricular (LV) diastolic filling in this subset of patients have not been well characterized.

METHODS

We evaluated the effects of acute volume loading on Doppler parameters of LV filling in 10 healthy control subjects and in 12 patients with idiopathic dilated cardiomyopathy (DCM). In patients with DCM, the effects of losartan on diastolic adaptation to volume load were also investigated.

RESULTS

During volume loading, the healthy control subjects showed a decrease in isovolumic relaxation time (F = 5.3, P <.05) but an increase in the LV peak filling rate (F = 52.9, P <.001) and velocity time integral of both systolic (F = 72.8, P <.001) and diastolic (F = 4.6, P <.05) pulmonary venous flow. In patients with DCM, isovolumic relaxation time decreased more than in control subjects (F = 8.1, P <.01), and the deceleration time of the early mitral wave was reduced (F = 26.3, P <.001). Furthermore, the duration of pulmonary venous flow reversal exceeded that of mitral flow at atrial contraction (F = 28.5, P <.001). After treatment with losartan, the deceleration time of early mitral wave remained unchanged, and the duration of pulmonary venous flow reversal at atrial contraction did not exceed that of mitral flow; thus, a significant treatment effect was detectable (F = 5.6, P <.05; and F = 6.6, P <.05, respectively).

CONCLUSIONS

Control subjects respond to volume load with enhancement in early LV filling, whereas patients with DCM show an increase of LV filling pressure. Diastolic adaptation to volume load improves in patients with DCM after treatment with losartan.

The atrial natriuretic peptide: a changing view

The atrial natriuretic peptide (ANP), a component of the natriuretic peptide family, was discovered in 1981 when de Bold and his coworkers observed a natriuretic effect induced by infusion of atrial extracts in rats. Subsequently, an impressive amount of research has been carried out in order to identify the structure of the active peptide and its receptors, to characterize the biological functions of ANP and its involvement in the pathophysiology of diseases and, finally, its direct contributory role in the pathogenesis of some cardiovascular disorders. ANP plays a key role in the regulation of salt and water balance, as well as of blood pressure homeostasis. In addition, ANP is involved in the pathophysiology of hypertension and heart failure, and exerts a cellular antiproliferative effect in the cardiovascular system. More recently, a direct contributory role of ANP in the development of hypertension and of cerebrovascular disorders has been suggested by the use of molecular genetic approaches. Therefore, our understanding of the pathophysiologic relevance of ANP has changed over time, finally leading to the identification of ANP as a potential determinant of cardiovascular diseases, rather than as a simple marker of cardiac and vascular dysfunctions. This novel view of ANP may open interesting research pathways.

Neuroendocrine and renal effects of intravascular volume expansion in compensated heart failure

To examine if the neuroendocrine link between volume sensing and renal function is preserved in compensated chronic heart failure [HF, ejection fraction 0.29 +/- 0.03 (mean +/- SE)] we tested the hypothesis that intravascular and central blood volume expansion by 3 h of water immersion (WI) elicits a natriuresis. In HF, WI suppressed ANG II and aldosterone (Aldo) concentrations, increased the release of atrial natriuretic peptide (ANP), and elicited a natriuresis (P < 0.05 for all) compared with seated control. Compared with control subjects (n = 9), ANG II, Aldo, and ANP concentrations were increased (P < 0.05) in HF, whereas absolute and fractional sodium excretion rates were attenuated [47 +/- 16 vs. 88 +/- 15 micromol/min and 0.42 +/- 0.18 vs. 0.68 +/- 0.12% (mean +/- SE), respectively, both P < 0.05]. When ANG II and Aldo concentrations were further suppressed (P < 0.05) during WI in HF (by sustained angiotensin-converting enzyme inhibitor therapy, n = 9) absolute and fractional sodium excretion increased (P < 0.05) to the level of control subjects (108 +/- 34 micromol/min and 0.70 +/- 0.23%, respectively). Renal free water clearance increased during WI in control subjects but not in HF, albeit plasma vasopressin concentrations were similar in the two groups. In conclusion, the neuroendocrine link between volume sensing and renal sodium excretion is preserved in compensated HF. The natriuresis of WI is, however, modulated by the prevailing ANG II and Aldo concentrations. In contrast, renal free water clearance is attenuated in response to volume expansion in compensated HF despite normalized plasma AVP concentrations.

Renal implications of the renin-angiotensin-aldosterone system blockade in heart failure

The renin-angiotensin-aldosterone system actively participates in the derangement of renal function since the early stages of heart failure (HF). A diminished capacity to excrete sodium secondary to increased proximal tubular re-absorption and loss of the renal functional reserve are the two most relevant initial alterations of renal function in which angiotensin II has been proven to act directly. Meanwhile, the octapeptide contributes to maintain glomerular filtration rate (GFR) within normal limits through efferent arteriole vasoconstriction. Administration of angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor antagonists (ARA) may thus be accompanied by a functional fall in that parameter. Advanced age, higher initial serum creatinine, history of hypertension, diabetes and atrial fibrillation predict the onset of GFR impairment associated with blockade of the renin-angiotensin system. Concomitant administration of betablockers may help to protect renal function, and preliminary data indicate that the combination of ACEi and ARA is not accompanied by a higher renal risk. The good prognostic effects of aldosterone antagonists in HF does not seem to be related to intrarenal effects of these compounds with the exception of preventing potassium loss and hypokalemia. The systematic therapeutic use of drug(s) provided with beneficial renal effects, to treat arterial hypertension or myocardial ischemia, may contribute to delay of, or prevent the development of HF.

Effects of losartan treatment on cardiac autonomic control during volume loading in patients with DCM

This study evaluated the effect of angiotensin II receptor blockade on cardiac autonomic control adaptation and urine output in response to acute isotonic volume load in patients with idiopathic dilated cardiomyopathy (DCM) and asymptomatic to mildly symptomatic heart failure. Left ventricular volumes and heart rate variability measurements were assessed at baseline and during intravenous saline load in 14 patients before and after 2 mo of losartan treatment. After losartan treatment, blood pressure values were lower, whereas left ventricular ejection fraction was higher (F = 79, P < 0.001), than before treatment. During saline load, ejection fraction decreased before losartan treatment (F = 5.6, P < 0.05) but did not change after treatment. Urinary volume, unchanged during saline load in untreated patients, increased after losartan (F = 9.38, P < 0. 001). Time-domain measurements that represent vagal modulation of heart rate (root-mean-square successive differences and percentage of differences between successive R-R intervals >50 ms) decreased during saline load in untreated patients (F = 3.1, P < 0.05 and F = 6.5, P < 0.01, respectively), but not after losartan. Similarly, a decrease in very low frequency (F = 3.2, P < 0.05), low-frequency (F = 2.9, P < 0.05), and high-frequency power (F = 6.1, P < 0.01) after saline load was observed only in untreated patients. In patients with DCM, losartan treatment improves the cardiac autonomic adaptation and increases urine output in response to volume overload.

Cardiac autonomic responses to volume overload in normal subjects and in patients with dilated cardiomyopathy

This study evaluated the effects of acute isotonic volume expansion on heart rate variability (HRV) in 10 patients with dilated cardiomyopathy (DCM) and in 10 age- and sex-matched normal volunteers. Echocardiographic left ventricular volumes and HRV measurements by continuous Holter recording were assessed at baseline, at 60 and 120 min during intravenous saline load (0.9% NaCl, 0.25 ml. kg(-1). min(-1)), and 60 min after infusion was terminated. Data analysis was performed by repeated-measures ANOVA. After volume expansion, left ventricular ejection fraction increased (F = 9.8; P < 0.001) in normal subjects and decreased (F = 8.7; P < 0.001) in DCM patients. During volume expansion a significant difference was also detectable between the two groups in root-mean-square successive difference (F = 25.2; P < 0.001), percentage of differences between successive normal R-R intervals >50 ms (F = 97.6; P < 0.001), high-frequency power (F = 50.1; P < 0.001), and low-frequency power (F = 41.6; P < 0.001), all of which reflect parasympathetic modulation of heart rate; in fact, these measurements increased in normal subjects and decreased in DCM patients. In normal subjects, the increase in HRV measurements during volume expansion suggests a parasympathetic activation, mediated by stimulation of cardiopulmonary and arterial mechanoreceptors. On the contrary, in DCM patients the parasympathetic withdrawal, already detectable at baseline, increases during volume expansion.

The effects of preoperative therapy with angiotensin-converting enzyme inhibitors on clinical outcome after cardiovascular surgery

OBJECTIVE

To determine the effect of preoperative therapy with angiotensin-converting enzyme (ACE) inhibitors on clinical outcome after cardiovascular surgery.

STUDY

Inception cohort.

SETTING

A tertiary care 54-bed cardiothoracic ICU.

PATIENTS

All admissions to an ICU over a 42-month period after cardiovascular surgery.

INTERVENTION

Extraction of preoperative, operative, and ICU data from a database.

OUTCOME MEASURES

Incidence of acute organ dysfunction, length of mechanical ventilation, ICU stay, and death after cardiovascular surgery.

RESULTS

The study cohort consisted of four groups: normal or moderately impaired left ventricular function control (group A, n=6,400); normal or moderately impaired left ventricular function treated with ACE inhibitors (group B, n=1,375); severe left ventricular dysfunction control (group C, n=1,905); and severe left ventricular dysfunction treated with ACE inhibitors (group D, n=1,650). The incidence of three or more organ dysfunction was similar on comparison of group A vs group B (5% vs 6%) or group C vs group D (15% vs 13%). There were no differences in the total duration of mechanical ventilation or length of stay in the ICU in group A vs group B or group C vs group D. Death occurred in 2% of groups A and B, and at 6% in groups C and D. Preoperative severe left ventricular dysfunction in both groups C and D was associated with an increased incidence of three or more organ dysfunction, duration of mechanical ventilation, length of stay in ICU, and death after surgery. Multivariate analysis indicated that therapy with ACE inhibitors did not affect the clinical outcome after cardiovascular surgery.

CONCLUSION

Preoperative therapy with ACE inhibitors did not influence the clinical outcome after cardiac surgery. It is unlikely that therapy with ACE inhibitors can alter the clinical sequelae of cardiopulmonary bypass and cardiac surgical procedures performed in high-risk patients because of underlying severe left ventricular dysfunction.

Hormonal and cardiorenal responses to acute saline loading in mild congestive heart failure--the effect of angiotensin converting enzyme inhibition

We investigated cardiorenal responses to acute saline loading in patients with mild congestive heart failure (CHF) with and without angiotensin-converting enzyme (ACE) inhibition. Saline loading (infusion of 250 ml of normal saline) was performed on 10 patients with mild CHF and 10 control subjects. Although saline loading reduced plasma renin activity and plasma angiotensin II to a similar extent in both groups, it increased cardiac output, renal blood flow, and the ratio of renal blood flow to cardiac output in the mild CHF group but not in the control group. After saline loading, urinary sodium excretion was higher in the control than in the mild CHF group. In the mild CHF group, saline loading was performed again after an ACE inhibitor (delapril) had been administered for 5 days. Although delapril increased cardiac output and renal blood flow under basal conditions, saline loading did not affect these variables. Delapril improved urinary sodium excretion after saline loading. Thus, the renin-angiotensin-aldosterone axis may contribute to cardiorenal hemodynamics and renal sodium handling in patients with mild CHF. This effect may attenuate the natriuretic response to acute saline loading, and administration of an ACE inhibitor improves this attenuation.

Transition from asymptomatic left ventricular dysfunction to congestive heart failure

One of the main goals of modern management and care of heart failure is to prevent the disease to progress toward congestion and death. The achievement of such an objective may, in fact, guarantee a sufficient quality of life and reduce the exposure of patients to the most common life-threatening complications associated with the congestive stage of the disease. Early identification of left ventricular dysfunction as well as a better knowledge of the mechanisms that favor the progression to more advanced stages of heart failure are fundamental requirements for the proper treatment of asymptomatic heart failure and for preventing the transition to symptomatic and more severe heart failure. The authors reviewed the literature on this topic, with emphasis on a series of studies they performed, to characterize the pathophysiologic profile of mild heart failure and the mechanisms that are possibly involved in the progression to congestive heart failure.

Alterations in metabolic clearance of atrial natriuretic peptides in heart failure: how do they relate to the resistance to atrial natriuretic peptides?

Deficiencies in activity of the atrial natriuretic peptide (ANP) system may be able to explain the disturbed electrolyte and fluid homeostasis occurring in chronic heart failure. Generally, in studies concerning the possible pathophysiologic role of ANP in heart failure, only the circulating levels of the hormone were measured. It has been shown, however, that plasma ANP levels exhibit marked variability attributable to the pulsatory pattern of secretion and to its very short plasma half-life. An evaluation of the main turnover parameters might represent a significant improvement in the assessment of the functioning of the overall ANP system. By using a tracer method, which does not alter the steady-state condition, a disturbed peripheral metabolism of ANP and a resistance to its biologic effects was demonstrated in patients with idiopathic dilated cardiomyopathy, even in those in the asymptomatic phase of the disease, showing ANP circulating levels, atrial pressure and volume, and cardiac index within the normal range. The altered degradation and distribution of ANP in patients with heart failure were demonstrated by a great increase in metabolic clearance (on average, 2.5-fold), production (on average, 6-fold), or both, and by a progressive reduction in the distribution spaces of the hormone when compared with normal subjects at the same sodium intake. The ratio between ANP disposal and the daily excretion of sodium (equal to the sodium intake in subjects at a strictly controlled sodium balance) may give a good index of the biologic activity (natriuresis) of the ANP system. Preliminary studies suggest that an index of biologic activity of the ANP system may be a useful tool for the comparison of the efficacy of different therapeutic strategies in heart failure. Indeed, after a 2-month treatment with an angiotensin-converting enzyme inhibitor, this index was returned to within the normal range, suggesting that the drug was able to "normalize" the peripheral distribution and degradation of the hormone in these patients. Although future studies in a large series of patients will be useful to assess this important issue, the setup of accurate methods able to evaluate the presence and degree of resistance to biologic activity of ANP may be a useful tool in the follow-up evaluation of patients with heart failure, and may pave the way for further progress in the knowledge of more general physiologic and pathophysiologic mechanisms of this important clinical condition.

Influence of angiotensin converting enzyme inhibition on relation of atrial natriuretic peptide concentration to atrial pressure in heart failure

OBJECTIVE

To examine the relation between haemodynamics and atrial natriuretic peptide concentration during short term angiotensin converting enzyme inhibition.

DESIGN

Patients were randomly allocated to receive placebo or one of three doses of the angiotensin converting enzyme inhibitor ramipril.

SETTING

Cardiac units of two tertiary referral hospitals.

SUBJECTS

38 Patients with stable congestive heart failure caused by ischaemic heart disease.

METHODS

Data were collected over a 24 hour period and assessed with the aim of distinguishing between the haemodynamic effects on plasma concentrations of atrial natriuretic peptide and the direct effects of the study drug, vasopressin concentrations, and angiotensin converting enzyme activity.

RESULTS

Pulmonary capillary wedge pressure was the main predictor of the plasma concentration of atrial natriuretic peptide. A higher plasma concentration of this peptide with a given pulmonary capillary wedge pressure was found after 24 hours of treatment with 2.5 mg and 5 mg of ramipril. Plasma concentration of the active metabolite, change in arginine vasopressin concentration or degree of angiotensin converting enzyme inhibition did not significantly predict change in plasma concentration of atrial natriuretic peptide or in the ratio of atrial natriuretic peptide concentration to pulmonary capillary wedge pressure.

CONCLUSIONS

A gradual increase in plasma concentration of atrial natriuretic peptide with a given pulmonary capillary wedge pressure, occurs during short term high degree inhibition of angiotensin converting enzyme. The causative mechanisms are yet to be identified. Such a change in the relation between central haemodynamics and atrial natriuretic peptide concentration may contribute to the beneficial effects of angiotensin converting enzyme inhibition in patients with congestive heart failure due to ischaemic heart disease.

Plasma renin activity in chagasic patients with and without congestive heart failure

Chagasic patients with advanced heart disease have fluid retention-dependent symptoms. Since fluid retention is mostly dependent on the renin-angiotensin-aldosterone system, chagasic patients with congestion related symptoms should have activation of the renin-angiotensin-aldosterone system. The purpose of this investigation was to determine the plasma renin activity baseline values of chagasic patients with and without congestive heart failure. Twenty-eight patients with positive serology for Chagas' disease were studied. Nineteen patients were asymptomatic (functional class I New York Heart Association) and nine were symptomatic (functional classes II-IV). Cardiac catheterization and ventricular cineangiography were performed on 20 patients. The symptomatic patients had significantly higher plasma renin activity levels (4.11 +/- 1.03 ng/ml/h) than the asymptomatic patients (1.08 +/- 0.11 ng/ml/h, P < 0.001) and the normal sedentary controls (1.65 +/- 0.22 ng/ml/h, P < 0.05, mean +/- S.E.). The plasma renin activity baseline values of the asymptomatic and symptomatic patients correlated directly with the baseline heart rate (r = 0.77, P < 0.0001). The symptomatic patients had larger ventricular volumes, moderately depressed ejection fractions and increased left ventricular end-diastolic pressures. The plasma renin activity baseline values also correlated directly with the left ventricular diastolic pressures (r = 0.70, P < 0.0006) and with the left ventricular diastolic (r = 0.66, P < 0.001) and systolic volumes (r = 0.67, P < 0.001). These results indicate that chagasic patients with fluid retention-dependent symptoms and hemodynamic evidence of left ventricular systolic dysfunction have activation of the renin-angiotensin-aldosterone system.

Blood levels of erythropoietin in congestive heart failure and correlation with clinical, hemodynamic, and hormonal profiles

Plasma levels of erythropoietin (mU/ml) were measured in patients with congestive heart failure (CHF) (n = 108) and in a control group of normal subjects (n = 45). In normal subjects, plasma levels of erythropoietin were 1.9 +/- 0.2. In patients with CHF, plasma levels of erythropoietin increased progressively according to New York Heart Association (NYHA) class (I: 1.4 +/- 0.2, n = 28; II: 5.4 +/- 0.8, n = 27; III: 9.6 +/- 2, n = 32; IV: 34 +/- 8, n = 21; F = 57.7, p < 0.001) and were significantly higher in NYHA classes II, III, and IV than in normal subjects. Plasma erythropoietin significantly decreased (from 43 +/- 14 to 12 +/- 3 mU/ml, p < 0.01) in patients with severe CHF (n = 9) when enalapril (20 mg/day administered orally) was added to long-term treatment for 3 weeks. Finally, in a subgroup of patients with NYHA class IV CHF (n = 9) and high plasma erythropoietin levels (37 +/- 9 mU/ml), packed red blood cell volume, assessed by the iodine-125-albumin dilution method, was higher than that in normal subjects (n = 11) (2,616 +/- 235 vs 2,028 +/- 119 ml, p < 0.05). The present study demonstrates that plasma erythropoietin levels are elevated in a large cohort of patients with CHF of varying etiology, and that this increase is related to the progression of the disease. The increase in circulating erythropoietin is associated with augmented packed red blood cell volume in patients with severe CHF. These results suggest a participation of erythropoietin in the complex neurohormonal response that occurs in CHF.