Low-dose continuous infusion of human atrial natriuretic peptide during and after cardiac surgery

Angiotensin Receptor-Neprilysin Inhibitor Suppresses Renin-Angiotensin-Aldosterone System Activation After Cardiac Surgery Using Cardiopulmonary Bypass

BACKGROUND

Sacubitril/valsartan, being both a neprilysin inhibitor and angiotensin receptor blocker, exhibits a renin-angiotensin-aldosterone system (RAAS) inhibitory effect. However, no study has investigated the administration of sacubitril/valsartan in patients early after surgery using cardiopulmonary bypass.

METHODS AND RESULTS

This was a prospective observational study of 63 patients who underwent open heart surgery and were treated with sacubitril/valsartan. No serious adverse events occurred. Among the 63 patients, sacubitril/valsartan was discontinued in 13 due to hypotension (n=10), renal dysfunction (n=2), and dizziness (n=1). Atrial natriuretic peptide concentrations increased significantly from Day 3 of treatment (P=0.0142 vs. Postoperative Day 1) and remained high thereafter. In contrast, plasma renin activity was significantly suppressed from Day 3 onwards (P=0.00206 vs. Postoperative Day 1). A decrease in creatinine concentrations and an increase in the estimated glomerular filtration rate were observed on Day 3; this improvement in renal function was not observed in the historical control group, in which patients did not receive sacubitril/valsartan. New postoperative atrial fibrillation was less frequent in the study group compared with the historical control (12.7% vs. 38.0%; P=0.0034).

CONCLUSIONS

Sacubitril/valsartan administration was safe immediately after open heart surgery in patients without postoperative hypotension. It enhanced serum atrial natriuretic peptide concentrations and suppressed RAAS activation.

Atrial natriuretic peptide T2238C gene polymorphism and the risk of cardiovascular diseases: A meta‑analysis

The present study aimed to investigate the association between atrial natriuretic peptide (ANP) T2238C (rs5065) gene polymorphism and the risk of cardiovascular disease. Relevant literature was obtained by searching databases. The odds ratios (ORs) of the ANP T2238C locus genotype distribution in the case group of cardiovascular diseases and the control group of a non-cardiovascular population were pooled using R software. Sensitivity analysis was used to verify the stability of the results. Egger's linear regression test was used to assess the publication bias of the included literature. Studies were classified according to quality assessment score of the Newcastle-Ottawa scale, year, region, sample size and underlying disease for subgroup analysis, and meta-regression analysis was performed. A total of 12 studies comprising 45,619 patients were included. ANP rs5065 mutant gene C allele was a significant risk factor for myocardial infarction relative to T allele (OR=2.55, 95% CI=1.47-4.43, P=0.0008), CC+CT genotype was a significant risk factor for cerebrovascular events relative to TT (OR=1.14, 95% CI=1.04-1.26, P=0.0048) and the mutant CC genotype was a potential risk factor for the composite cardio-cerebral vascular events (CVE) relative to CT+TT (OR=1.40, 95% CI=0.96-2.04, P=0.081). In studies fulfilling the Hardy-Weinberg equilibrium, the CC genotype was a significant risk factor for the composite CVE relative to TT (OR=2.39, 95% CI=1.40-4.10, P=0.0018) and the CC genotype was a significant risk factor for composite CVE relative to CT+TT (OR=2.41, 95% CI=1.41-4.13, P=0.0015). The P-value of the Egger's test for publication bias was 0.436, which was not statistically significant. The results of the sensitivity analysis were relatively stable. Subgroup analysis indicated that the publication year was a potential source of heterogeneity. Regression analysis was performed for the recessive model in the composite CVE and the results showed that the study region (Europe) was one of the sources of heterogeneity (P=0.016). In conclusion, ANP 2238T/C mutation may increase the risk of myocardial infarction, cerebrovascular events and composite CVE.

Effects of atrial natriuretic peptide on renal function during cardiopulmonary bypass: a randomized pig model

OBJECTIVES

Acute kidney injury is a well-known complication after cardiac surgery and cardiopulmonary bypass (CPB). In this experimental animal study, we evaluated the effects of atrial natriuretic peptide (ANP) on renal function, perfusion, oxygenation and tubular injury during CPB.

METHODS

Twenty pigs were blindly randomized to continuous infusion of either ANP (50 ng/kg/min) or placebo before, during and after CPB. Renal blood flow as well as cortical and medullary perfusion was measured. Blood was repeatedly sampled from the renal vein. Glomerular filtration rate was measured by infusion clearance of 51Cr-EDTA.

RESULTS

Glomerular filtration rate was higher (P < 0.001), whereas renal blood flow or renal oxygen delivery was not affected by ANP during CPB. Renal oxygen consumption did not differ between groups during CPB, whereas renal oxygen extraction was higher in the ANP group (P = 0.03). Urine flow and sodium excretion were higher in the ANP group during CPB. Blood flow in the renal medulla, but not in the cortex, dropped during CPB, an effect that was not seen in the animals that received ANP.

CONCLUSIONS

ANP improved renal function during CPB. Despite impaired renal oxygenation, ANP did not cause tubular injury, suggesting a renoprotective effect of ANP during CPB. Also, CPB induced a selectively reduced blood flow in the renal medulla, an effect that was counteracted by ANP.

Effect of low-dose atrial natriuretic peptide in critically ill patients with acute kidney injury: a retrospective, single-center study with propensity-score matching

Background

Acute kidney injury (AKI) is a major comorbidity in critically ill patients. Low-dose atrial natriuretic peptide (ANP) has been shown to effectively prevent acute kidney injury (AKI), especially in cardiovascular surgery patients. However, its treatment effects for AKI in critically ill patients are unclear.

Methods

This single-center, retrospective, observational study included patients with AKI diagnosed within 7 days after intensive care unit (ICU) admission during the period January 2010 to December 2017. We conducted a propensity-matched analysis to estimate the treatment effect of low-dose carperitide (a recombinant human ANP) on the clinical outcomes. The primary outcome was a composite of death, renal replacement therapy dependence, or no recovery from AKI (defined as an increase of the serum creatinine level to ≥200% of baseline) at hospital discharge.

Results

During the study period, 4479 adult patients were admitted to the ICU. We identified 1374 eligible patients with AKI diagnosed within 7 days after ICU admission. Among these patients, 346 (25.2%) were treated with low-dose carperitide, with an average dose of 0.019 μg kg^− 1 min^− 1. The primary outcome occurred more often in the treatment group than in the control group (29.7% versus 23.4%, respectively; p = 0.022). After propensity score matching, characteristics of 314 patients from each group were well- balanced. Significant difference of the primary outcome, as seen with the full cohort, was no longer obtained; no benefit of carperitide was detected in the matched cohort (29.0% versus 25.2%; p = 0.281).

Conclusions

Low-dose ANP showed no treatment effect in general critically ill patients who developed AKI.

Low-dose atrial natriuretic peptide for prevention or treatment of acute kidney injury: a systematic review and meta-analysis

Background

Theoretically, atrial natriuretic peptide (ANP), especially low-dose ANP, is beneficial in acute kidney injury (AKI). In this study, we examined whether low-dose ANP is effective in preventing or treating AKI by conducting an updated systematic review for randomized controlled trials (RCTs).

Method

We searched the Excerpta Medica database (EMBASE), PubMed, and Cochrane CENTRAL databases for RCTs that compare the effects of low-dose ANP (≤ 50 ng/kg/min) with a placebo or conventional therapy in at-risk patients or patients with AKI. The primary outcome was the incidence of new AKI (in prevention RCTs), while the secondary outcomes were in-hospital mortality rate, renal replacement therapy (RRT) requirement, length of hospital and intensive care unit (ICU) stay, incidence of hypotension, and peak serum creatinine levels. The risk-of-bias was evaluated using the Cochrane Collaboration risk-of-bias tool. Trial sequential analysis (TSA) was used for each outcome of interest.

Results

A total of 18 RCTs (16 prevention and two treatment trials) fulfilled our inclusion criteria. In prevention RCTs, the incidence of new AKI was significantly low in the low-dose ANP group (relative risk [RR] = 0.51; 95% confidence interval [CI] = 0.36–0.72; P = 0.0001) compared to the control group. In addition, the low-dose ANP group showed a significantly reduced RRT requirement in both prevention (RR = 0.17; 95% CI = 0.04–0.64; P = 0.009) and treatment (RR = 0.43; 95% CI = 0.20–0.93; P = 0.03) RCTs. Among secondary outcomes, in some cases, low-dose ANP was associated with a reduction in ICU and in-hospital stay. The risk-of-bias assessment and TSA results indicated that the sample sizes and qualities of the RCTs were insufficient to conclude the efficacy of low-dose ANP.

Conclusion

Low-dose ANP might be effective in preventing or treating AKI. However, the evidence accumulated so far is not strong enough to demonstrate ANP’s beneficial effects. The next step is to elucidate the effects of low-dose ANP by conducting multicenter, high-quality, large-sample RCTs.

Trial registration

PROSPERO registry CRD42017068568. Registered 20 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2330-z) contains supplementary material, which is available to authorized users.

Natriuretic Peptides in Cardiac Anesthesia and Intensive Care

Natriuretic peptides, predominantly B-type, are widely used in cardiology as prognostic and diagnostic biomarkers or, much less often, as a substantive treatment tool. They are hormones that are produced mainly in the myocardium in response to overload and ischemia, and their level quite accurately reflects the degree of myocardial dysfunction. Although their use in cardiac anesthesia and intensive care setting seems to be very beneficial for assessing the risk of acute disturbance of myocardial function or its laboratory monitoring, the actual significance of natriuretic peptides in this area is not yet recognized. This is due to the lack of clear diagnostic and prognostic values for these biomarkers supported by high-quality researches. On the basis of the available data, main advantages, existing difficulties, and most effective ways of using natriuretic peptides for determining the risk of heart surgery and assessing the severity of sepsis, pneumonia, and other critical conditions have been discussed in this review. In addition, the expediency of using natriuretic peptides as target parameters for goal-oriented therapy and as a substantive tool for treatment is considered.

State-of the-art review on the renal and visceral protection during open thoracoabdominal aortic aneurysm repair

During open thoracoabdominal aortic aneurysm repair (OTAAAR), there is an inevitable organ ischemic period that occurs when the abdominal arteries are being reattached to the aortic graft. Despite various protective techniques, the incidence of renal and visceral complications remains substantial. This state-of-the-art review gives an overview of the current and most evidence-based organ protection methods during OTAAAR, based on the most recent publications and personal experience. An electronic search was performed in four medical databases, using the following MeSH terms: thoracoabdominal aneurysm, TAAAR, visceral protection, renal protection, kidney, perfusion, and intestines. Every publication type was considered. The literature search was ended on August 31st, 2017. The left heart bypass (LHB) is currently the most frequent adjunct to provide distal aortic perfusion (DAP) during aortic clamping. Together with systemic hypothermia, it forms the cornerstone in organ protection during aortic clamping. Further renal protection can be obtained by selective renal perfusion (SRP) with cold blood or cold crystalloid solution, the latter enriched with mannitol. The perfusion should be administered in a volume- and pressure-controlled way and, if possible, by use of a pulsatile pump. Selective visceral perfusion (SVP) is not routinely used, as it does not provide adequate blood flow for visceral protection. The best way to protect the intestines is by minimizing the ischemic time. The preservation of renal and visceral function after OTAAAR can only be obtained with specific strategies before, during, and after the operation. This involves a series of measures, including selective digestive decontamination (SDD), avoidance of nephrotoxic drugs, minimizing the renal and intestinal ischemic time, systemic cooling, avoidance of hemodynamic instability, and regional protective perfusion of the kidneys. Future innovations in catheters, cardiac bypass flow types, mechanical components, hybrid vascular grafts, and pharmaceutical protection measures will hopefully further reduce organ complications.

Comparative Efficacy of Drugs for Preventing Acute Kidney Injury after Cardiac Surgery: A Network Meta-Analysis

BACKGROUND

Acute kidney injury (AKI) occurs frequently after cardiac surgery and has been associated with increased hospital length of stay, mortality, and costs.

OBJECTIVE

We aimed to evaluate the efficacy of pharmacologic strategies for preventing AKI after cardiac surgery.

METHODS

We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) up to 6 May 2017 and the reference lists of relevant articles about trials. The outcome was the occurrence of AKI. This is the first network meta-analysis of the different prevention strategies using Bayesian methodology.

RESULTS

The study included 63 articles with 19,520 participants and evaluated the effect of ten pharmacologic strategies to prevent AKI in patients undergoing cardiac surgery. Compared with placebo, the odds ratio (OR) for the occurrence of AKI was 0.24 [95% confidence interval (CI) 0.16-0.34] with natriuretic peptide, 0.33 (95% CI 0.14-0.70) with fenoldopam, 0.54 (95% CI 0.31-0.84) with dexmedetomidine, 0.56 (95% CI 0.29-0.95) with low-dose erythropoietin, 0.63 (95% CI 0.43-0.88) with levosimendan, 0.76 (95% CI 0.52-1.10) with steroids, 0.83 (95% CI 0.48-1.40) with high-dose erythropoietin, 0.85 (95% CI 0.64-1.14) with N-acetylcysteine, 0.96 (95% CI 0.69-1.29) with sodium bicarbonate, and 1.05 (95% CI 0.70-1.41) with statins. The surface under the cumulative ranking curve probabilities indicated that natriuretic peptide was the best treatment therapy and that fenoldopam ranked second.

CONCLUSIONS

Natriuretic peptide is probably the preferred pharmacologic strategy to prevent AKI in adult patients undergoing cardiac surgery, especially in those at high risk of AKI.

Treatment of Patients with Cardiac Surgery Associated-Acute Kidney Injury

Members of the Acute Dialysis Quality Initiative (ADQI) participated in a 3-day conference in Vicenza in May 2007 to evaluate the available literature on this topic and draft consensus recommendations for research studies in this area. This report summarizes the available evidence and describes the key questions that will need to be addressed with the goal of standardizing the care of patients with cardiac surgery-associated acute kidney injury (CSA-AKI) and improving outcomes.

ScaI atrial natriuretic peptide gene polymorphisms and their possible association with postoperative atrial fibrillation - a preliminary report

INTRODUCTION

Atrial fibrillation (AF) is a frequently encountered complication after coronary artery bypass grafting (CABG), but its underlying mechanisms are still unclear. The natriuretic peptides have been reported as markers for predicting the occurrence of postoperative AF. This study evaluates whether the ScaI ANP gene polymorphisms predict the occurrence of postoperative AF.

MATERIAL AND METHODS

A prospective study of 203 consecutive patients with coronary artery disease undergoing elective CABG was undertaken for atrial natriuretic peptide (ANP) ScaI gene polymorphism. Several perioperative data were analysed. Postoperative AF was defined as lasting for at least 15 min, confirmed by 12-lead ECG and occurring within 6 postoperative days. The ScaI polymorphism of the ANP gene was determined by polymerase chain reaction (PCR). Size-dependent separation of the PCR products on a polyacrylamide gel was followed by staining with ethidium bromide.

RESULTS

The total frequency of AF was 19.7%. The frequencies of ScaI ANP gene polymorphisms were as follows: A1A1 4.90%, A1A2 59.60% and A2A2 35.46%. In order to assess the hypothesis that the A2 allele is a marker of increased risk of postoperative atrial fibrillation, the odds ratio (OR) was calculated: A2 vs. non-A2, OR = 0.98 (0.23-4.1), p = 0.97, which was not significant. The odds ratios for A2A2 and A1A1 were not significant either: A2A2 vs. non-A2A2, OR = 1.11 (0.54-2.29), p = 0.76, and A1A1 vs. non-A1A1, OR = 1.17 (0.23-5.92), p = 0.84.

CONCLUSIONS

ANP genotype did not predispose to the incidence of "new-onset" AF.

The protective effect of human atrial natriuretic peptide on renal damage during cardiac surgery

Purpose

Acute kidney injury (AKI) is one of the critical complications after cardiac surgery. In the kidney, angiotensin II (Ang II) is formed by independent mechanisms, and activity of the intrarenal renin–angiotensin–aldosterone (RAAS) system contributes to the progression of kidney damage. Although atrial natriuretic peptide (ANP) exerts protective effects against renal injury by inhibiting the RAAS, the mechanisms of this effect have not been completely clarified. We investigated how human ANP (hANP) could prevent renal damage induced by cardiopulmonary bypass.

Methods

Forty-eight patients undergoing cardiac surgery were divided into two groups, with and without hANP infusion. Urinary angiotensinogen, neutrophil gelatinase-associated lipocalin (NGAL) and L-type fatty acid-binding protein (L-FABP) were measured during and after surgery in both groups. Plasma renin activity, Ang II, aldosterone and serum creatinine were also measured.

Results

Urinary angiotensinogen levels in the hANP group were significantly lower than in the non-hANP group after cardiopulmonary bypass surgery, at the end of surgery and 3 h after surgery. At 3 h after surgery, urinary NGAL levels in the hANP and non-hANP groups were 371.1 ± 413.6 and 761.4 ± 437.8 μg/gCr, respectively (p < 0.01). Urinary L-FABP levels at the end of surgery in the hANP and non-hANP groups were 238.8 ± 107.4 and 573.9 ± 370.1 μg/gCr, respectively (p < 0.01). Moreover, hANP seemed to significantly reduce the incidence of postoperative AKI.

Conclusions

hANP demonstrated renal protective effects during cardiac surgery, and could possibly reduce the incidence of AKI after ischemia–reperfusion surgery. Moreover, this protective effect of hANP is likely induced by inhibition of the intrarenal RAAS.

Renin-Angiotensin System Control for Chronic Kidney Disease Patients Undergoing Coronary Surgery

PURPOSE

We investigated the effectiveness of active renin-angiotensin-aldosterone system (RAAS) control with human atrial natriuretic peptide (hANP) and an angiotensin II receptor blocker (ARB) in patients with chronic kidney disease (CKD) undergoing coronary artery bypass grafting (CABG).

METHODS

A total of 286 consecutive patients with CKD undergoing CABG were divided into three groups: Group C (n = 50) receiving placebo, the hANP group (n = 60) receiving hANP, and the active RAAS control therapy (ARC) group (n = 56) receiving hANP plus an ARB. Renal function, brain natriuretic peptide (BNP) and RAAS parameters were analyzed.

RESULTS

After 1 year, renal function parameters were better in the hANP and ARC groups compared with group C, and the dialysis rate was significantly lower (group C: 12%, hANP group: 1.7%, ARC group: 1.8%, p = 0.018) in the hANP and ARC groups. BNP levels were significantly lower in the hANP and ARC groups compared with group C (p = 0.001). There was also a significant difference of aldosterone among the groups (p = 0.023), as well as a significant difference between group C and the ARC group (p = 0.017).

CONCLUSIONS

The present study showed that active RAAS control preserved renal function in patients with CKD undergoing CABG. The improved early postoperative outcome with RAAS control may lead to long-term inhibition of cardiovascular events.

Efficacy of Carperitide in Hemodialysis Patients Undergoing Cardiac Surgery

PURPOSE

Recently, performance of cardiac surgery in hemodialysis patients has increased, but the mortality rate is high.

METHODS

We retrospectively examined the early and long-term outcomes in 128 dialysis patients who underwent cardiac surgery with or without carperitide infusion and were followed for 2 years. Sixty-three patients received carperitide infusion during surgery and 65 patients did not.

RESULTS

The hospital mortality rate was 1.6% in the carperitide group and 12.3% in the non-carperitide group, being significantly lower in the carperitide group. The 2-year actuarial survival rate was 90.5% ± 3.7% in the carperitide group, and 76.9% ± 5.2% in the non-carperitide group, while the major adverse cardiovascular and cerebrovascular events (MACCE)-free rate at 2 years postoperatively was 90.5% ± 3.7% in the carperitide group and 67.7% ± 5.8% in the non-carperitide group.

CONCLUSIONS

These findings suggest that carperitide improves the early postoperative outcome in dialysis patients undergoing cardiac surgery, as has already been demonstrated in non-dialysis patients. An early postoperative cardioprotective effect of carperitide and improvement of renal function in oliguric patients might have contributed to this outcome. However, this was a retrospective study, so a prospective investigation is required to demonstrate the mechanisms involved. In addition, further evaluation of the long-term results would be desirable.

Atrial natriuretic factor in normothermic and hypothermic cardiopulmonary bypass

Background: To evaluate the plasmatic changes of atrial natriuretic factor (ANF) during and after cardiopulmonary bypass (CPB) in normothermia and hypothermia.

Methods: Twenty-three patients (n=23) undergoing coronary artery bypass graft surgery were randomly assigned to two groups. In Group I (n=11), the patients underwent operation in normothermia; in Group II (n=12), the operation was performed in hypothermia (268C).

Results: Plasma ANF levels were determined after induction of anaesthesia, at the end of CPB and one hour postoperatively. There were no demographic differences between the two groups, diuresis (p=0.90) and natriuresis (p=0.95). Plasma levels of ANF were significantly elevated during and after CPB in both groups (p <0.01). The groups differed significantly for plasma levels of ANF during CPB and postoperatively ( p<0.05), but did not differ prebypass (p=0.08). There was no correlation in either group between ANF release and central venous pressure, natriuresis and diuresis. There was only a borderline relationship between ANF concentration and diuresis after CPB in Group I.

Conclusion: CPB triggers the production and release of ANF. The present study demonstrates a significantly enhanced ANF release during hypothermia and reperfusion after ischaemia. Thus, these data suggest the protective role of ANF on the hypoxic myocardium, and they confirm that ANF does not play a role in diuresis and natriuresis during and after hypothermic CPB.

Carperitide Increases the Need for Renal Replacement Therapy After Cardiovascular Surgery

OBJECTIVES

Acute kidney injury is a common complication after aortic surgery. Carperitide, a human atrial natriuretic peptide, was reported to be effective for preventing acute kidney injury after cardiac surgery. However, most studies were from single centers, and results of meta-analyses are subject to publication bias. The aim of the present study was to investigate whether carperitide preserved renal function in patients undergoing cardiovascular surgery.

DESIGN

Retrospective cohort study.

SETTING

Participating hospitals (N = 281) in a national database from 2010 to 2013.

PARTICIPANTS

Adult patients (N = 47,032) who underwent cardiovascular surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main intervention variable investigated was the use of carperitide on the day of surgery. Assessed outcomes included receiving renal replacement therapy within 21 days of surgery and in-hospital mortality. Data were available for 47,032 patients, of whom 2,186 (4.6%) received carperitide on the day of surgery. Multivariate logistic regression analysis revealed that carperitide was significantly associated with a greater likelihood of receiving renal replacement therapy within 21 days of surgery, but not with in-hospital mortality.

CONCLUSIONS

In patients undergoing cardiovascular surgery, carperitide significantly increased the odds of receiving renal replacement therapy within 21 days after surgery.

Carperitide and atrial fibrillation after coronary bypass grafting: the Nihon University working group study of low-dose HANP infusion therapy during cardiac surgery trial for postoperative atrial fibrillation

BACKGROUND

Occurrence of atrial fibrillation after cardiac surgery is associated with long-term mortality. We investigated whether infusion of human atrial natriuretic peptide (carperitide) could prevent postoperative atrial fibrillation.

METHODS AND RESULTS

A total of 668 patients who underwent isolated coronary artery bypass grafting were randomized to receive infusion of carperitide or physiological saline from the initiation of cardiopulmonary bypass. Patients were monitored continuously for 1 week after surgery to detect atrial fibrillation. The risk factors were investigated by Cox proportional hazard model. Postoperative atrial fibrillation occurred in 41 of 335 patients (12.2%) from the carperitide group versus 110 of 333 patients (32.7%) from the placebo group (P<0.0001). Postoperative levels of angiotensin-II, aldosterone, creatine kinase MB isoenzyme, human heart fatty acid-binding protein, and brain natriuretic peptide were all significantly lower in the carperitide group. The risk factors for postoperative atrial fibrillation by the Cox proportional hazard model were an age ≥70 years, emergency surgery, preoperative aldosterone level >150 ng/mL, preoperative nonuse of angiotensin receptor antagonists, preoperative use of calcium antagonists, postoperative nonuse of β-blockers, postoperative nonuse of aldosterone blockers, and nonuse of carperitide.

CONCLUSIONS

-Perioperative carperitide infusion reduced the occurrence of postoperative atrial fibrillation. Accordingly, carperitide could be a useful option for preventing postoperative atrial fibrillation.

CLINICAL TRIAL REGISTRATION

-URL: http://www.umin.ac.jp. Unique Identifier: UMIN000003958.

Effects of continuous infusion of low-dose human atrial natriuretic peptide (hANP) on the lungs during cardiac surgery

OBJECTIVE

The objective of this study was to determine the effects of a continuous infusion of low-dose hANP on the lungs during cardiac surgery in patients under cardiopulmonary bypass (CPB).

METHODS

We analyzed 30 consecutive cases of cardiac surgery performed at our hospital from 2007-2008. The patients were divided into a group that received hANP (hANP group) or a group that received saline and no hANP (N-hANP group). We measured various parameters before and after surgery using a PiCCO monitor.

RESULT

There were no differences in the preoperative characteristics between the groups, although urine volume during the operation was significantly greater in the hANP group. After surgery, there were no significant differences between the groups in cardiac output index (CI), global enddiastolic volume index (GEDVI), intrathoracic blood volume index (ITBI), pulmonary blood volume index (PBI), extravascular lung water index (ELWI) and pulmonary vascular permeability index (PVPI), total protein, and creatine. In contrast, interleukin-6 (IL-6) and renin were significantly lower, and albumin was significantly higher in the hANP group.

CONCLUSION

We found that low-dose hANP during open cardiac surgery inhibited the secretion and plasma activity of IL-6 and renin. Although there were no differences in lung circulatory parameters such as the amount of fluid in the pulmonary blood vessels between the two groups, we believe that the strong diuretic effect of hANP reduced third-space fluid retention caused by CPB.

Reduction in the incidence of acute kidney injury after aortic arch surgery with low-dose atrial natriuretic peptide: a randomised controlled trial

BACKGROUND

Acute kidney injury (AKI) after surgery is associated with an increased risk of adverse events and death. Atrial natriuretic peptide (ANP) dilates the preglomerular renal arteries and inhibits the renin-angiotensin axis. A low-dose ANP infusion increases glomerular filtration rate after cardiovascular surgery, but it is not known whether it reduces the incidence of AKI or the mortality rate.

OBJECTIVE

To evaluate whether an intravenous ANP infusion prevents AKI in patients undergoing aortic arch surgery requiring hypothermic circulatory arrest.

DESIGN

A randomised controlled study.

SETTING

Operating room and intensive care unit at Kawasaki Saiwai Hospital, Kanagawa, Japan.

PATIENTS

Forty-two patients with normal preoperative renal function undergoing elective repair of an aortic arch aneurysm.

INTERVENTION

Patients were assigned randomly to receive a fixed dose of ANP (0.0125 μg (-1) kg(-1)  min) or placebo. The infusion was started after induction of anaesthesia and continued for 24  h postoperatively.

MAIN OUTCOME MEASURES

The primary end-point was the incidence of AKI within 48 h after surgery.

RESULTS

AKI developed in 30% of patients who received ANP compared with 73% of patients who received placebo (P = 0.014). Intraoperative urine output was almost 1 l greater in patients who received ANP (1865 ± 1299 versus 991 ± 480  ml in the control group, P = 0.005). However, there were no differences in mean arterial pressure or number of episodes of hypotension between the groups. Length of hospital and intensive care stays were not significantly different, nor was there a difference in 30-day mortality. No patients required haemodialysis or continuous renal replacement therapy.

CONCLUSION

We found that an intravenous infusion of ANP at 0.0125  μg  kg(-1)  min(-1) is an effective intervention for reducing the incidence of postoperative AKI, and appears to afford a degree of renal protection during and after cardiovascular surgery.

TRIAL REGISTRATION

Kawasaki ANP trial, UMIN Clinical Trials Registry ID: UMIN000011650.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

Results of low-dose carperitide infusion in high-risk patients undergoing coronary artery bypass grafting

BACKGROUND

This study investigated the efficacy of human atrial natriuretic peptide (hANP, carperitide) for high-risk patients undergoing coronary artery bypass grafting (CABG).

METHODS

This was a randomized controlled trial of 367 high-risk patients (European System for Cardiac Operative Risk Evaluation above 6) undergoing CABG. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE). Secondary endpoints were (1) postoperative death, (2) MACCE + hemodialysis, and (3) serum creatinine and brain natriuretic peptide (BNP) levels. Logistic regression analysis was conducted to identify preoperative and perioperative factors related to early death and MACCE.

RESULTS

There was no significant difference of survival between the hANP and placebo groups (p = 0.1651), but the MACCE-free rate was significantly higher in the hANP group than in the placebo group (p < 0.0001). No patient from the hANP group started hemodialysis after operation, but 7 patients did in the placebo group, and the dialysis rate was significantly lower in the hANP group (p = 0.0147). Serum creatinine and BNP were also significantly lower in the hANP group at 1 year postoperatively. MACCE were strongly associated with age 75 years or older, chronic kidney disease, hemodialysis, left ventricular dysfunction, and nonuse of carperitide.

CONCLUSIONS

In the early postoperative period, carperitide has a cardiorenal protective effect that prevents postoperative MACCE and hemodialysis. Perioperative low-dose carperitide infusion may be useful in high-risk patients undergoing on-pump CABG.

Early results of human atrial natriuretic peptide infusion in non-dialysis patients with chronic kidney disease undergoing isolated coronary artery bypass grafting: the NU-HIT trial for CKD-II

BACKGROUND

Chronic kidney disease (CKD) is an important risk factor for cardiac surgery. In the most recently reported NU-HIT trial for CKD with CKD patients underwent coronary artery bypass grafting (CABG) as subjects, carperitide was reported to be effective in terms of renal function. In the present study, a subanalysis was performed on patients registered in the NU-HIT trial for CKD from the standpoint of renin-angiotensin system, natriuresis and renal function.

METHODS

303 patients with CKD who underwent isolated CABG were divided into a group that received carperitide infusion and another group without carperitide. The renin activity, angiotensin-II, aldosterone, urine-sodium, urine- creatinine, fractional sodium excretion, renal failure index, and BNP levels.

RESULTS

There were significant lower in hANP group than the placebo group, in angiotensin-II at one day postoperatively, and in aldosterone from 0 day to one month postoperatively. FENa was significantly lower in the hANP group at 3 day and one week postoperatively.

CONCLUSIONS

In on pump isolated CABG patients with CKD, carperitide showed a potent natriuretic action and inhibited the renin-angiotensin system, suggesting that it prevented deterioration of postoperative renal function. Our findings raise new possibilities for the perioperative and postoperative management of patients undergoing surgery with cardiopulmonary bypass.

Results of emergency coronary artery bypass grafting for acute myocardial infarction: importance of intraoperative and postoperative cardiac medical therapy

BACKGROUND

The results of emergency coronary artery bypass grafting (CABG) for acute myocardial infarction (AMI) are less than satisfactory, and readmission for cardiac events is common.

METHODS AND RESULTS

105 patients underwent emergency CABG for AMI. We examined the long-term results of emergency CABG for AMI from the viewpoints of preoperative, intraoperative, and postoperative factors. The operative mortality rate was 11.4%. Risk factors for early death were age ≥80 years, shock, veno-arterial bypass, creatine kinase isoenzyme Mb ≥100 U/L, non-use of a left internal thoracic artery graft and an extracorporeal circulation time ≥120 min. Risk factors for late cardiac events were ejection fraction <40%, non-use of human atrial natriuretic peptide (hANP) therapy, angiotensin II receptor blockers (ARB) and aldosterone blockers, and a 3-month postoperative brain natriuretic peptide level ≥200 pg/ml.

CONCLUSIONS

Early results of this study are similar to those seen in previous reports, whereas late phase results yield some new and interesting findings. We suggest that intraoperative hANP, and postoperative aldosterone blocker and ARB, following CABG for AMI, will, through control of the renin-angiotensin-aldsterone system, inhibit left ventricular remodelling, reduce the extent of infarction, and improve cardiac function, yielding a favourable long-term prognosis.

Multicenter trial of carperitide in patients with renal dysfunction undergoing cardiovascular surgery

PURPOSE

The aim of this study was to evaluate the efficacy of carperitide in maintaining renal function during intraoperative and postoperative management of patients with renal dysfunction undergoing elective cardiovascular surgery.

METHODS

The subjects were 88 patients with a preoperative serum creatinine level ≥1.2 mg/dl who underwent elective cardiovascular surgery using cardiopulmonary bypass. They were prospectively divided into a group that received carperitide from the start of surgery (carperitide group, n = 44) and a group that was not given carperitide (control group, n = 44). Carperitide infusion was initiated at the beginning of surgery and was continued for ≥5 days, with the central dose being 0.02 g/kg/min. The primary endpoint was the serum creatinine level on postoperative day (POD) 3.

RESULTS

The serum creatinine levels on PODs 3, 4, and 7 were significantly lower, and creatinine clearance on PODs 2 and 3 was significantly higher in the carperitide group than in the controls. One patient in the control group and no patient in the carperitide group required continuous hemodiafiltration, but the difference was not statistically significant.

CONCLUSION

Continuous low-dose infusion of carperitide from the start of cardiovascular surgery maintained renal function in patients with preoperative renal dysfunction.

Low-dose atrial natriuretic peptide for chronic kidney disease in coronary surgery

PURPOSE

Chronic kidney disease (CKD) is an independent risk factor for cardiovascular disease. We investigated the effectiveness of human atrial natriuretic peptide (hANP) infusion in CKD patients undergoing coronary artery bypass grafting (CABG).

PATIENTS AND METHODS

We analyzed 134 consecutive cases in which CABG had been performed in our hospital from 2002 to 2005. They were divided into four groups: Group A (n = 19) was CKD + placebo, Group B (n = 30) was non-CKD + placebo, Group C (n = 22) was CKD + hANP, and Group D (n = 63) was non-CKD + hANP). The serum creatinine (mg/dl) and estimated glomerular filtration rate (ml/min/1.73 m²) were measured as evaluation values.

RESULTS

The value of sCr changed preoperatively and at 1 year postoperatively from 1.09 ± 0.09, 51.3 ± 4.4 to 1.26 ± 0.42, 49.4 ± 14.4 in Group A, from 0.77 ± 0.14, 75.5 ± 12.1 to 0.91 ± 0.40, 72.3 ± 19.5 in Group B, from 0.99 ± 0.12, 54.8 ± 3.0 to 0.93 ± 0.16, 64.2 ± 12.3 in Group C and from 0.77 ± 0.13, 77.7 ± 13.4 to 0.83 ± 0.17, 75.9 ± 16.2 in Group D, respectively. There was a significant difference between Group A and Group C regarding the change of creatinine (p =0.0022).

CONCLUSION

Our study has confirmed that an infusion of hANP during CABG in patients with CKD not only improves perioperative renal function, but also prevents the progression of CKD.

Pharmacological therapies for the prevention of acute kidney injury following cardiac surgery: a systematic review

Post-cardiac surgery acute kidney injury (AKI) is common and is associated with a significant increase in morbidity and mortality. We aimed to systematically review randomised trials that assessed the renoprotective utility of pharmacological agents in patients undergoing cardiac surgery. We searched PubMed, Embase and the Cochrane Central Register of Controlled Trials for randomised controlled trials comparing renoprotective pharmacological interventions with control in adult patients undergoing cardiac surgery with cardiopulmonary bypass. We extracted data for mortality, need for renal replacement therapy (RRT), incidence of AKI, and creatinine clearance at 24-48 h. About 49 randomised controlled trials involving 4605 patients were included. Pharmacological interventions included dopamine, fenoldopam, calcium channel antagonists, natriuretic peptides, diuretics, and N-acetylcysteine. Most trials were of poor quality, with small sample sizes, under-reporting of randomisation procedure, allocation concealment and method of blinding. No pharmacological intervention significantly reduced mortality. Fenoldopam and Atrial Natriuretic Peptide (ANP) reduced the need for renal replacement therapy by 5% (NNT 20, 95% CI 11.3, 83.0) and 3.5% (NNT 29, 95% CI 17.1, 84.4), respectively. Brain Natriuretic Peptide resulted in a 10% reduction in the incidence of AKI (NNT 11, 95% CI 6.2, 32.0). Dopamine caused a significant reduction in creatinine clearance (-4.26 ml/min, 95% CI -7.14, -1.39). The quality of studies that have assessed pharmacological renoprotective agents in cardiac surgery is generally poor. Fenoldopam, ANP and BNP show evidence of renoprotection. Randomised studies evaluating the effect of novel renoprotective agents that are powered to detect clinically relevant differences in outcomes are required.

Cardiovascular and renal effects of carperitide and nesiritide in cardiovascular surgery patients: a systematic review and meta-analysis

INTRODUCTION

Acute kidney injury (AKI) following cardiovascular surgery is a common disease process and is associated with both morbidity and mortality. The aim of our study was to evaluate the cardiovascular and renal effects of an atrial natriuretic peptide (ANP, carperitide) and a B-type (or brain) natriuretic peptide (BNP, nesiritide) for preventing and treating AKI in cardiovascular surgery patients.

METHODS

Electronic databases, including PubMed, EMBASE and references from identified articles were used for a literature search.

RESULTS

Data on the infusion of ANP or BNP in cardiovascular surgery patients was collected from fifteen randomized controlled trials and combined. The infusion of ANP or BNP increased the urine output and creatinine clearance or glomerular filtration rate, and reduced the use of diuretics and the serum creatinine levels. A meta-analysis showed that ANP infusion significantly decreased peak serum creatinine levels, incidence of arrhythmia and renal replacement therapy. The meta-analysis also showed that ANP or BNP infusion significantly decreased the length of ICU stay and hospital stay compared with controls. However, the combined data were insufficient to determine how ANP or BNP infusion during the perioperative period influences long-term outcome in cardiovascular surgery patients.

CONCLUSIONS

The infusion of ANP or BNP may preserve postoperative renal function in cardiovascular surgery patients. A large, multicenter, prospective, randomized controlled trial will have to be performed to assess the therapeutic potential of ANP or BNP in preventing and treating AKI in the cardiovascular surgical setting.

Myocardial protective effect of human atrial natriuretic Peptide in cardiac surgery. -hANP Shot” in clinical safety trial-

BACKGROUND

We studied low-dose human atrial natriuretic peptide (hANP) infusion therapy during cardiac surgery and reported the cardiac and renal protective effects. The efficacy of a bolus injection of hANP (the "hANP shot") simultaneously with induction of cardioplegia has been proven in animal experiments. In the present study the clinical effects of this "hANP shot" were examined.

METHODS AND RESULTS

The subjects were 67 patients undergoing Coronary artery bypass grafting. At the time of inducing cardioplegia, 1 group received a simultaneous bolus injection of 100 μg of hANP (hANP group) and the other group received an injection of physiological saline (placebo group). The primary endpoints were (1) operative mortality and complications, and (2) the creatine kinase isoenzyme MB (CPK-MB), troponin-I, and human heart fatty acid binding protein (H-FABP) levels. The secondary endpoints were (1) the incidence of arrhythmia, and levels of (2) atrial and B-type natriuretic peptides, and cyclic guanosine monophosphate (cGMP), and (3) renin, angiotensin II, and aldosterone. Postoperative CPK-MB, troponin-I, and H-FABP levels were significantly lower in the hANP group than in the placebo group. Postoperative arrhythmia was significantly less frequent in the hANP group than in the placebo group.

CONCLUSIONS

It is possible to achieve cardioprotective effects based on the safety of the "hANP shot", as well as from biomarkers of ischemia and results related to arrhythmia. The "hANP shot" should also be evaluated as a safer and new cardioprotective method for cardiac surgery.

Landiolol hydrochloride for prevention of atrial fibrillation after coronary artery bypass grafting: new evidence from the PASCAL trial

OBJECTIVE

Atrial fibrillation occurs frequently after cardiac surgery and not only prolongs hospitalization but also influences the prognosis. We investigated whether landiolol hydrochloride, an ultrashort-acting beta-blocker, could reduce postoperative atrial fibrillation in a randomized controlled trial.

METHODS

The subjects were 140 patients undergoing coronary artery bypass grafting at the Nihon University School of Medicine. The primary end point was occurrence/non-occurrence of atrial fibrillation up to 1 week postoperatively. Logistic regression analysis was performed to investigate risk factors for atrial fibrillation among preoperative, perioperative, and postoperative variables.

RESULTS

Atrial fibrillation occurred in 7 patients (10%) in the landiolol group versus 24 patients (34.3%) in the placebo group; the landiolol group had a significantly lower incidence (P = .0006). Postoperative heart rate was significantly lower in the landiolol group than in the placebo group. On returning to the intensive care unit, the landiolol group had significantly lower inflammatory and ischemic parameters. Medical costs were also significantly lower in the landiolol group. Multivariate analysis revealed that significant risk factors for atrial fibrillation were a European System for Cardiac Operative Risk Evaluation of 10 or more, preoperative non-use of angiotensin receptor blockers, and non-use of landiolol.

CONCLUSIONS

Postoperative atrial fibrillation was reduced by treatment with landiolol hydrochloride. Amelioration of ischemia, an anti-inflammatory effect, and inhibition of sympathetic hypertonia by landiolol presumably reduced the occurrence of atrial fibrillation. Hypotension or bradycardia did not develop in any of the patients, indicating the safety of this beta-blocker. These findings suggest that landiolol hydrochloride could be useful in the perioperative management of patients undergoing cardiac surgery.

Roles of atrial natriuretic peptide and its therapeutic use

Since the discovery of atrial natriuretic peptide (ANP), there has been tremendous progress in our understanding of the physiologic and pathophysiologic, diagnostic, and therapeutic roles of ANP. The diagnostic application of ANP and brain natriuretic peptide (BNP) has been reviewed by many investigators, and meta-analyses of therapeutic use of BNP were reported from the USA. However, there are few reviews concerning the therapeutic use of ANP in patients with various conditions. Therefore, this review focuses on the recent clinical evidence of ANP in therapeutic use and experimental data that rationally support the therapeutic use of ANP.

Long-term results (three-year) of emergency coronary artery bypass grafting for patients with unstable angina pectoris

Satisfactory results are achieved by elective coronary artery bypass grafting (CABG), but the results of emergency CABG are less than satisfactory and readmission for cardiac events is common. We examined long-term results of emergency CABG for unstable angina pectoris from the viewpoints of preoperative, intraoperative, and postoperative factors. Subjects were 154 patients who underwent emergency CABG for unstable angina pectoris. Operative mortality rate was 1.9%. Univariate analysis showed female gender, chronic renal failure, hemodialysis, nonuse of human atrial natriuretic peptide (hANP), nonuse of angiotensin II receptor blockers and aldosterone blockers, 3-month postoperative brain natriuretic peptide level > or =200 pg/ml, and 3-month postoperative aldosterone level > or =100 pg/ml as risk factors for late cardiac events. Multivariate analysis confirmed nonuse of hANP, nonuse of aldosterone blockers, 3-month brain natriuretic peptide level > or =200 pg/ml, and 3-month aldosterone level > or =100 pg/ml as risk factors. Intraoperative hANP infusion and postoperative treatment with aldosterone blockers and angiotensin II receptor blockers can control the renin-angiotensin-aldosterone system, inhibit left ventricular remodeling, decrease extent of infarction, and improve cardiac function, yielding a favorable long-term prognosis. The best results are obtained by combining good surgical technique and perioperative management with the long-term outcome in mind.

Effects of continuous venovenous hemofiltration on the pharmacology of carperitide, a recombinant human atrial natriuretic peptide

BACKGROUND

Natriuretic peptides exert vasodilatory, natriuretic, and diuretic effects and inhibit renin and aldosterone secretion. Carperitide, a recombinant alpha-human atrial natriuretic peptide (hANP), is used for the treatment of cardiac failure. Patients with renal failure often require renal replacement therapy, and little is known about the pharmacokinetics of carperitide when used for renal replacement therapy.

METHODS AND RESULTS

Eleven patients who received continuous carperitide infusion and needed continuous venovenous hemofiltration (CVVHF) for acute renal failure were observed. The plasma hANP concentration was noted and the hANP clearance during CVVHF was calculated. The results indicated that infused hANP was removed by CVVHF. Although the clearance of hANP by CVVHF was relatively lower than the expected whole body clearance, CVVHF slightly reduced plasma hANP and cyclic guanosine monophosphate concentrations and increased arterial pressure.

CONCLUSIONS

CVVHF affects the pharmacology of infused hANP in critically ill patients. Some caution with respect to blood pressure may be necessary when carrying out CVVHF for critically ill patients receiving continuous infusion of natriuretic peptides.

Prevention and treatment of acute kidney injury in patients undergoing cardiac surgery: a systematic review

BACKGROUND

Acute kidney injury (AKI) is common in patients undergoing cardiac surgery and is associated with a high rate of death, long-term sequelae and healthcare costs. We conducted a systematic review of randomized controlled trials for strategies to prevent or treat AKI in cardiac surgery.

METHODS

We screened Medline, Scopus, Cochrane Renal Library, and Google Scholar for randomized controlled trails in cardiac surgery for prevention or treatment of AKI in adults.

RESULTS

We identified 70 studies that contained a total of 5,554 participants published until November 2008. Most studies were small in sample size, were single-center, focused on preventive strategies, and displayed wide variation in AKI definitions. Only 26% were assessed to be of high quality according to the Jadad criteria. The types of strategies with possible protective efficacy were dopaminergic agents, vasodilators, anti-inflammatory agents, and pump/perfusion strategies. When analyzed separately, dopamine and N-acetylcysteine did not reduce the risk for AKI.

CONCLUSIONS

This summary of all the literature on prevention and treatment strategies for AKI in cardiac surgery highlights the need for better information. The results advocate large, good-quality, multicenter studies to determine whether promising interventions reliably reduce rates of acute renal replacement therapy and mortality in the cardiac surgery setting.

Experimental investigation of direct myocardial protective effect of atrial natriuretic peptide in cardiac surgery

OBJECTIVE

Human atrial natriuretic peptide has recently become known not only as a heart failure drug but also for myocardial protection. We investigated its direct myocardial protective effect on ischemia-reperfusion injury in cardiac surgery.

METHODS

Male pigs (35-45 kg) undergoing surgery with cardiopulmonary bypass, with 60-minute reperfusion after 30-minute cardioplegia, were grouped by timing of atrial natriuretic peptide administration: group C (n = 8), no atrial natriuretic peptide (cardioplegia only); group H1 (n = 8); 100-mug atrial natriuretic peptide administration after aortic crossclamping; group H2 (n = 8), administration before aortic declamping; and group H1 + H2 (n = 8), administration both after crossclamping and before declamping. Blood and myocardial cyclic guanosine monophosphate, calcium, and residual adenosine triphosphate levels were determined. Histologic investigation was conducted by electron and optical microscopy.

RESULTS

Atrial natriuretic peptide increased blood and myocardial cyclic guanosine monophosphate levels (P < .0001, P < .0001, P < .007 H1 + H2 vs C; P < .0014, P < .0007, P < .003 H1 vs C), decreased myocardial calcium (P < .0038 H1 + H2 vs C), and increased myocardial residual adenosine triphosphate. Electron microscopy revealed ischemic changes in mitochondria and nuclei in group C but not in treatment groups.

CONCLUSIONS

Ischemia-reperfusion injury was inhibited with equal effectiveness by atrial natriuretic peptide both during ischemia and immediately before reperfusion, acting directly on myocardium through cyclic guanosine monophosphate. Atrial natriuretic peptide may be useful as a supportive measure for patients with long aortic crossclamping time or difficulties in weaning from cardiopulmonary bypass.

Atrial natriuretic peptide for preventing and treating acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is common in hospitalised patients and is associated with significant morbidity and mortality. Despite recent advances, outcomes have not substantially changed in the last four decades. Atrial natriuretic peptide (ANP) has shown promise in animal studies, however randomised controlled trials (RCTs) have shown inconsistent clinical benefits.

OBJECTIVES

To assess the benefits and harms of ANP for preventing and treating AKI.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE and EMBASE and reference lists of retrieved articles.

SELECTION CRITERIA

RCTs that investigated all forms of ANP versus any other treatment in adult hospitalised patients with or "at risk" of AKI.

DATA COLLECTION AND ANALYSIS

Results were expressed as risk ratios (RR) with 95% confidence intervals (CI) or mean difference (MD). Outcomes were analysed separately for low and high dose ANP for preventing or treating AKI.

MAIN RESULTS

Nineteen studies (11 prevention, 8 treatment; 1,861 participants) were included. There was no difference in mortality between ANP and control in either the low or high dose prevention studies. Low (but not high) dose ANP was associated with a reduced need for RRT in the prevention studies (RR 0.32, 95% CI 0.14 to 0.71). Length of hospital and ICU stay were significantly shorter in the low dose ANP group. For established AKI, there was no difference in mortality with either low or high dose ANP. Low (but not high) dose ANP was associated with a reduction in the need for RRT (RR 0.54, 95% CI 0.30 to 0.98). High dose ANP was associated with more adverse events (hypotension, arrhythmias). After major surgery there was a significant reduction in RRT requirement with ANP in the prevention studies (RR 0.56, 95% CI 0.32 to 0.99), but not in the treatment studies. There was no difference in mortality between ANP and control in either the prevention or treatment studies. There was a reduced need for RRT with low dose ANP in patients undergoing cardiovascular surgery (RR 0.35, 95% CI 0.18 to 0.70). ANP was not associated with outcome improvement in either radiocontrast nephropathy or oliguric AKI.

AUTHORS' CONCLUSIONS

ANP may be associated with improved outcomes when used in low doses for preventing AKI and in managing postsurgery AKI and should be further explored in these two settings. There were no significant adverse events in the prevention studies, however in the high dose ANP treatment studies there were significant increases hypotension and arrhythmias.

Influence of continuous infusion of low-dose human atrial natriuretic peptide on renal function during cardiac surgery: a randomized controlled study

OBJECTIVES

The purpose of this study was to determine the effect of human atrial natriuretic peptide (hANP) in patients who underwent coronary artery bypass grafting (CABG) on renal function.

BACKGROUND

Acute renal failure after cardiac surgery is associated with high morbidity and mortality.

METHODS

A total of 504 patients who underwent CABG were divided into 2 groups: 1 group received hANP at 0.02 microg/kg/min from the start of cardiopulmonary bypass (hANP group), and 1 group did not receive hANP (placebo group). Various parameters were measured before and after surgery.

RESULTS

There was no difference in mortality between the 2 groups, but post-operative complications were less frequent in the hANP group (p = 0.0208). In the hANP group, serum creatinine (Cr) was significantly lower and urinary Cr and Cr clearance were significantly higher from post-operative day 1 to week 1. The maximum post-operative Cr level and percent increase of Cr were significantly lower in the hANP group (p < 0.0001). Patients with Cr exceeding 2.0 mg/dl included 1 in the hANP group and 8 in the placebo group, showing a significant difference (p = 0.0374). Four patients in the placebo group and none in the hANP group required hemodialysis, but the difference was not statistically significant.

CONCLUSIONS

Continuous infusion of low-dose hANP from the start of cardiopulmonary bypass effectively maintained post-operative renal function. Infusion of hANP prevents early post-operative acute renal failure and helps to achieve safer cardiac surgery. (

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000001440).

Hypothermic Circulatory Arrest: Renal Protection by Atrial Natriuretic Peptide

Moderate hypothermic circulatory arrest with selective cerebral perfusion has been developed for cerebral protection during thoracic aortic surgery. However, visceral organs, particularly the kidneys, suffer greater tissue damage under moderate hypothermic circulatory arrest, and acute renal failure after hypothermic circulatory arrest is an independent risk factor for early and late mortality. This study investigated whether atrial natriuretic peptide could prevent the reduction in renal perfusion and protect renal function after moderate hypothermic circulatory arrest. Twelve pigs cooled to 30°C during cardiopulmonary bypass were randomly assigned to a peptide-treated group of 6 and a control group of 6. Moderate hypothermic circulatory arrest was induced for 60 min. Systemic arterial mean pressure and renal artery flow did not differ between groups during the study. However, renal medullary blood flow increased significantly in the peptide-treated group after hypothermic circulatory arrest. Myeloperoxidase activity was significantly reduced in the medulla of the peptide-treated group. Renal medullary ischemia after hypothermic circulatory arrest was ameliorated by atrial natriuretic peptide which increased medullary blood flow and reduced sodium reabsorption in the medulla. Atrial natriuretic peptide also reduced the release of an inflammatory marker after ischemia in renal tissue.