Saphenous vein graft aneurysm fistula formation causing right heart failure: an unusual presentation

Saphenous vein graft aneurysm (SVG) formation after coronary artery bypass grafting is a rare complication of the surgery. We present a case of a 68-year-old man with an unusual presentation of such an aneurysm. Thirty-four years after his initial bypass surgery, the patient presented with a fistula formation into his right atrium from a vein graft aneurysm. Late aneurysm formation is thought to occur secondary to atherosclerotic degeneration of the SVG with background hypertension and dyslipidaemia accelerating the process. Diagnostic modalities used to investigate SVG aneurysms include computed tomography, transthoracic echocardiogram, magnetic resonance imaging and cardiac catheterisation. Aneurysms with fistula formation historically require aggressive surgical intervention. Resection of the aneurysm with subsequent revascularisation if required is the surgical norm. SVG aneurysm with fistula formation into a cardiac chamber is a rare complication of coronary artery bypass grafting (CABG), which can occur with atypical presenting symptoms. Physicians should keep in mind the possibility of this occurring in post-CABG patients presenting with heart failure and a new murmur.

Prediction of cardiac rhythm 1 year following cardioversion for atrial fibrillation

BACKGROUND

There is little recent information regarding outcome and its determinants following cardioversion (CV) for atrial fibrillation (AF) or flutter. This study aims to help improve prediction of cardiac rhythm outcome following CV for AF.

METHODS

Cardiac rhythm at 6 weeks and 12 months was documented following elective (EC; n=496) or immediate (IC; n=52) cardioversion for AF or atrial flutter in a single referral centre.

RESULTS

65 and 58% of IC patients remained in sinus rhythm (SR) 6 weeks and 1 year after CV (respectively) compared with 43% and 30% in EC patients (P<0.001). Independent positive predictors of SR 6 weeks after cardioversion included amiodarone therapy (OR 2.04 [1.28-3.33], P<0.01) and atrial flutter (OR 1.85 [1.09-3.13], P<0.05). Negative predictors included the need for >1 shock to achieve SR (OR 1.61 [1.12-2.37], P=0.011) and arrhythmia duration, (OR 0.96 [0.95-0.97], P<0.001). At 1 year, amiodarone, duration of arrhythmia and the need for >1 shock remained independent predictors of rhythm.

CONCLUSIONS

The number of shocks required to achieve SR is a newly demonstrated independent predictor of rhythm outcome after elective CV.

Comparison of high sensitivity and contemporary troponin assays for the early detection of acute myocardial infarction in the emergency department

Background

Current guidelines define acute myocardial infarction (AMI) by the rise and/or fall of cardiac troponin with ≥1 value above the 99th percentile. Past troponin assays have been unreliable at the lower end of the range. Highly sensitive assays have therefore been developed to increase the clinical sensitivity for detection of myocardial injury.

Methods

Three hundred and thirty-two patients with chest pain suggestive of AMI were prospectively recruited between November 2006 and April 2007. Serial blood samples were analysed to compare Roche Elecsys high sensitivity troponin T (hsTnT), Abbott Architect troponin I 3rd generation (TnI 3) and Roche Elecsys troponin T (TnT) for the diagnosis of AMI.

Results

One hundred and ten (33.1%) patients were diagnosed with AMI. Test performance for the diagnosis of AMI, as quantified by receiver operating characteristic area under the curve (95% confidence intervals) for baseline/follow-up troponins were as follows: hsTnT 0.90 (0.87–0.94)/0.94 (0.91–0.97), TnI 3 0.88 (0.84–0.92)/0.93 (0.90–0.96) and TnT 0.80 (0.74–0.85)/0.89 (0.85–0.94). hsTnT was superior to TnT ( P < 0.001/0.013 at baseline/follow-up) but equivalent to TnI 3. For patients with a final diagnosis of AMI, baseline troponins were raised in more patients for hsTnT (83.6%) than TnI 3 (74.5%) and TnT (62.7%). A delta troponin of ≥20% increased the specificity of hsTnT from 80.6% to 93.7% but reduced sensitivity from 90.9% to 71.8%.

Conclusion

hsTnT was superior to TnT but equivalent to TnI 3 for the diagnosis of AMI. Serial troponin measurement increased test performance. hsTnT was the most likely to be raised at baseline in those with AMI. A delta troponin increases specificity but reduces sensitivity.

Urocortin 2 infusion in human heart failure

AIMS

To document the haemodynamic, neurohormonal, and renal responses to Urocortin 2 (UCN2) infused in human heart failure (HF).

METHODS AND RESULTS

Eight male patients with HF [left ventricular ejection fraction (LVEF) < 40%, NYHA class II-III] received placebo and 25 [low dose (LD)] and 100 microg [high dose (HD)] of UCN2 intravenously over 1 h in a single-blind, placebo-controlled, dose-escalation design. UCN2 increased cardiac output (CO) (mean peak increments +/- SEM; placebo 0.3 +/- 0.1; LD 1.0 +/- 0.3; HD 2.0 +/- 0.2 L/min; P < 0.001) and LVEF (0.0 +/- 1.5; LD 5.9 +/- 2.1; HD 14.1 +/- 2.7%; P = 0.001) and decreased mean arterial pressure (placebo 6.7 +/- 1.3; LD 11.4 +/- 1.7; HD 19.4 +/- 3.3 mmHg; P = 0.001), systemic vascular resistance (SVR) (placebo 104 +/- 37; LD 281 +/- 64; HD 476 +/- 79 dynes s/cm(5); P < 0.003), and cardiac work (CW) (placebo 48 +/- 12; LD 66 +/- 22; HD 94 +/- 13 mmHg/L/min; P < 0.001). No significant effect on vasoconstrictor/volume-retaining neurohormones was noted. UCN2 decreased urinary volume (P = 0.035) but not creatinine excretion (P = 0.962).

CONCLUSION

Intravenous UCN2 in HF induced increases in CO and LVEF with falls in SVR and CW. No hormone response occurred. The role of UCN2 in circulatory regulation and its potential therapeutic application in heart disease warrant further investigation.

B-type natriuretic peptide infusions in acute myocardial infarction

BACKGROUND

Natriuretic peptides have actions likely to ameliorate cardiac dysfunction. B-type natriuretic peptide (BNP) is indicated as treatment for decompensated cardiac failure.

OBJECTIVE

To determine the utility of BNP in acute myocardial infarction (MI).

DESIGN

Double-blind randomised placebo-controlled trial.

SETTING

Tertiary hospital coronary care unit.

PATIENTS

28 patients with acute MI with delayed or failed reperfusion and moderate left ventricular dysfunction.

INTERVENTIONS

Infusion of BNP or placebo for 60 hours after MI.

MAIN OUTCOME MEASURES

Neurohormonal activation and renal function in response to BNP infusion, secondary end points of echocardiographic measures of left ventricular function and dimension.

RESULTS

BNP infusion resulted in a significant rise in BNP (276 pg/l vs 86 pg/l, p = 0.001). NT-proBNP levels were suppressed by BNP infusion (p = 0.002). Atrial natriuretic peptide (ANP) and NT-proANP levels fell with a significant difference in the pattern between BNP infusion and placebo during the first 5 days (p<0.005). C-type natriuretic peptide (CNP) and NT-proCNP levels rose during the infusion with higher levels than placebo at all measurements during the first 3 days (p<0.01). Cyclic guanosine monophosphate (cGMP) was raised during the infusion period showing a peak of 23 pmol/l on day 2 (placebo 8.9 pmol/l, p = 0.002), with a correlation between BNP and cGMP levels (p<0.001). Glomerular filtration rate (GFR) fell with BNP infusion but was not significantly lower than with placebo (71.0 (5.6) vs 75.8 (5.4) ml/min/1.73 m2, p = 0.62). Patients receiving nesiritide exhibited favourable trends in left ventricular remodelling.

CONCLUSIONS

Nesiritide, given soon after MI, induced increments in plasma cGMP and CNP and decrements in other endogenous cardiac peptides with a neutral effect on renal function and a trend towards favourable ventricular remodelling.

Hemoglobin and N-terminal pro-brain natriuretic peptide: Independent and synergistic predictors of mortality in patients with acute heart failure

BACKGROUND

Hemoglobin and amino-terminal pro-brain natriuretic peptide (NT-proBNP) are both independent predictors of mortality in patients with chronic HF. Their combined predictive power for mortality in the setting of acute HF is uncertain.

METHODS

In an international prospective cohort design, we evaluated the relationships between hemoglobin, NT-proBNP, and 60-day mortality in 690 patients with acute HF.

RESULTS

The median hemoglobin for the entire cohort was 13.0 g/dL (interquartile range 11.6-14.3). The WHO criterion for anemia was met by 44% (n=305). The 60-day mortality rate for anemic patients was 16.4% vs. 8.8% in non-anemic patients (p<0.001). Anemia was an independent predictor of short-term mortality (OR=1.72, 95% CI=1.05-2.80, p=0.03), as was a NT-proBNP concentration >5180 pg/mL (OR=2.32, 95% CI=1.36-3.94 p=0.002). Consideration of four risk groups: not anemic/low NT-proBNP (reference group, n=220), anemic/low NT-proBNP (n=152), not anemic/high NT-proBNP (n=165), and anemic/high NT-proBNP (n=153) revealed respective 60-day mortality rates of 5.0% (referent), 9.2% (OR=1.93, 95% CI=0.85-4.36; p=0.12), 13.9% (OR=3.07, 95% CI=1.45-6.50, p=0.003), and 23.5% (OR=5.84, 95% CI=2.87-11.89, p<0.001).

CONCLUSIONS

Anemia was common in this cohort of subjects with acute HF and was related to adverse short-term outcome. Integrated use of hemoglobin and NT-proBNP measurements provides powerful additive information and is superior to the use of either in isolation.

Effect of Body Mass Index on Diagnostic and Prognostic Usefulness of Amino-Terminal Pro–Brain Natriuretic Peptide in Patients With Acute Dyspnea

BACKGROUND

Amino (N)-terminal pro-brain natriuretic peptide (NT-proBNP) testing is useful for diagnostic and prognostic evaluation in patients with dyspnea. An inverse relationship between body mass index (BMI); (calculated as weight in kilograms divided by height in meters squared) and NT-proBNP concentrations has been described.

METHODS

One thousand one hundred three patients presenting to the emergency department with acute dyspnea underwent analysis. Patients were classified into the following 3 BMI categories: lean (<25.0), overweight (25.0-29.9), and obese (>/=30.0).

RESULTS

The NT-proBNP concentrations in the overweight and obese groups were significantly lower than in the lean patients, regardless of the presence of acute heart failure (P<.001). The positive likelihood ratio for an NT-proBNP-based diagnosis of acute heart failure was 5.3 for a BMI lower than 25.0, 13.3 for a BMI of 25.0 to 29.9, and 7.5 for a BMI of 30.0 or higher. A cut point of 300 ng/L had very low negative likelihood ratios in all 3 BMI categories (0.02, 0.03, and 0.08, respectively). Among decedents, the NT-proBNP concentrations were lower in the overweight and obese patients compared with the lean subjects (P<.001). Nonetheless, a single cut point of 986 ng/L strongly predicted 1-year mortality across the 3 BMI strata, regardless of the presence of acute heart failure (hazard ratios, 2.22, 3.06, and 3.69 for BMIs of <25.0, 25.0-29.9, and >/=30.0, respectively; all P<.004); the risk associated with a high NT-proBNP concentration was detected early and was sustained to a year after baseline in all 3 BMI strata (all P<.001).

CONCLUSIONS

In patients with and without acute heart failure, the NT-proBNP concentrations are relatively lower in overweight and obese patients with acute dyspnea. Despite this, the NT-proBNP concentration retains its diagnostic and prognostic capacity across all BMI categories.

Angiotensinogen M235T and T174M Gene Polymorphisms in Combination Doubles the Risk of Mortality in Heart Failure

Angiotensinogen M235T and T174M polymorphisms have individually been associated with elevated levels of plasma angiotensinogen, hypertension, and left ventricular hypertrophy. In this study, heart failure patients (n=451) were genotyped for the angiotensinogen M235T and T174M polymorphisms to investigate association with survival (recorded over 4 years of follow-up) and prognostic hormone markers. Patients carrying the 235TT genotype (n=86) were 3 years younger at admission ( P =0.011), and, in those with hypertension, diagnosis was made ≈10 years earlier than other patients. Patients carrying ≥1 174M allele (n=94) were more likely to have a previous history of heart failure ( P =0.044) and increased mortality during follow-up (risk ratio: 1.69, 95% CI: 1.03 to 2.79; P =0.038) compared with 174TT homozygotes (n=355), despite having a higher left ventricular ejection fraction ( P =0.009). “High-risk” genotype combinations (defined a priori as 235TT and/or ≥1 174M allele; n=144; 32%) were independently predictive of mortality, conferring a 2-fold greater risk of dying during the follow-up period (odds ratio: 2.0; 95% CI: 1.3 to 3.0; P =0.001). This study suggested that angiotensinogen gene variants M235T and T174M may provide prognostic information for long-term survival in heart failure patients.

Urocortin 2 infusion in healthy humans: hemodynamic, neurohormonal, and renal responses

OBJECTIVES

We sought to examine the effects of urocortin (UCN) 2 infusion on hemodynamic status, cardiovascular hormones, and renal function in healthy humans.

BACKGROUND

Urocortin 2 is a vasoactive and cardioprotective peptide belonging to the corticotrophin-releasing factor peptide family. Recent reports indicate the urocortins exert important effects beyond the hypothalamo-pituitary-adrenal axis upon cardiovascular and vasohumoral function in health and cardiac disease.

METHODS

We studied 8 healthy unmedicated men on 3 separate occasions 2 to 5 weeks apart. Subjects received placebo, 25-microg low-dose (LD), and 100-microg high-dose (HD) of UCN 2 intravenously over the course of 1 h in a single-blind, placebo-controlled, dose-escalation design. Noninvasive hemodynamic indexes, neurohormones, and renal function were measured.

RESULTS

The administration of UCN 2 dose-dependently increased cardiac output (mean peak increments +/- SEM) (placebo 0.5 +/- 0.2 l/min; LD 2.1 +/- 0.6 l/min; HD 5.0 +/- 0.8 l/min; p < 0.001), heart rate (placebo 3.3 +/- 1.0 beats/min; LD 8.8 +/- 1.8 beats/min; HD 17.8 +/- 2.1 beats/min; p < 0.001), and left ventricular ejection fraction (placebo 0.6 +/- 1.4%; LD 6.6 +/- 1.5%; HD 14.1 +/- 0.8%; p < 0.001) while decreasing systemic vascular resistance (placebo -128 +/- 50 dynes x s/cm(5); LD -407 +/- 49 dynes x s/cm(5); HD -774 +/- 133 dynes.s/cm(5); p < 0.001). Activation of plasma renin activity (p = 0.002), angiotensin II (p = 0.001), and norepinephrine (p < 0.001) occurred only with the higher 100-mug dose. Subtle decreases in urine volume (p = 0.012) and natriuresis (p = 0.001) were observed.

CONCLUSIONS

Brief intravenous infusions of UCN 2 in healthy humans induced pronounced dose-related increases in cardiac output, heart rate, and left ventricular ejection fraction while decreasing systemic vascular resistance. Subtle renal effects and activation of plasma renin, angiotensin II, and norepinephrine (at high-dose only) were observed. These findings warrant further investigation of the role of UCN 2 in circulatory regulation and its potential therapeutic application in heart disease.

Amino-Terminal Pro-Brain Natriuretic Peptide, Renal Function, and Outcomes in Acute Heart Failure

OBJECTIVES

We sought to study the individual and integrative role of amino-terminal pro-brain natriuretic peptide (NT-proBNP) and parameters of renal function for prognosis in heart failure.

BACKGROUND

Amino-terminal pro-BNP and renal impairment both predict death in patients with heart failure. Worsening of renal function in heart failure even defines the "cardiorenal syndrome."

METHODS

Seven hundred twenty subjects presenting with acute heart failure from 4 university-affiliated medical centers were dichotomized according to NT-proBNP concentration and baseline glomerular filtration rate. In addition, patients were divided according to changes in renal function. The primary end point was 60-day mortality.

RESULTS

The combination of a glomerular filtration rate (GFR) <60 ml/min/1.73 m2 with an NT-proBNP >4,647 pg/ml was the best predictor of 60-day mortality (odds ratio 3.46; 95% confidence interval 2.13 to 5.63). Among subjects with an NT-proBNP above the median, those with a GFR <60 ml/min/1.73 m2 or a creatinine rise > or =0.3 mg/dl had the worst prognosis, whereas in subjects with a NT-proBNP below the median, prognosis was not influenced by either impaired renal function at presentation or the development of renal impairment during admission.

CONCLUSIONS

The combination of NT-proBNP with measures of renal function better predicts short-term outcome in acute heart failure than either parameter alone. Among heart failure patients, the objective parameter of NT-proBNP seems more useful to delineate the "cardiorenal syndrome" than the previous criteria of a clinical diagnosis of heart failure.

NTproBNP-guided drug treatment for chronic heart failure: design and methods in the “BATTLESCARRED” trial

BACKGROUND

How best to decide when to introduce drugs and what doses are optimal in individual patients with chronic heart failure (CHF), is unclear.

AIMS

We will determine whether titration of drug treatment according to plasma NTproBNP is superior regarding clinical outcomes to intensive standardised clinical assessment; whether either of the regimens noted above is superior to usual care; and whether age alters the relative efficacy of NTproBNP guided treatment.

METHODS

We will randomise 360 patients, stratified by age, to drug treatment directed by plasma NTproBNP, to intensive standardised clinical assessment, or to usual care. The primary outcome is total mortality, and secondary outcomes include death plus hospital admission for any cardiovascular event plus episodes of outpatient decompensated heart failure. Analyses will be conducted at the end of one and two years.

RESULTS

308 patients have been recruited, the majority being in NYHA functional class II, 60.6% being >75 years. The entry plasma NTproBNP level is 238, 50-1250 pmol/l, median and range, approximately 400-11,000 pg/ml.

CONCLUSION

We describe details of a study to test the potential utility of serial measurements of NTproBNP in adjusting the drug treatment of patients with CHF. Projected completion date is 2007.

Usefulness of intermediate amino-terminal pro-brain natriuretic peptide concentrations for diagnosis and prognosis of acute heart failure

Age-stratified cutpoints for aminoterminal pro-brain natriuretic peptide (NT-pro-BNP) concentrations are diagnostic in 83% of all subjects with acute dyspnea. This study analyzed subjects with NT-pro-BNP concentrations between the "rule-out" and "rule-in" cutpoints, the so-called natriuretic peptide gray zone. NT-pro-BNP concentrations, clinical characteristics, and 60-day mortality were studied in 1,256 acutely dyspneic patients from an international multicenter study. Of all subjects, 215 had gray-zone NT-pro-BNP concentrations, 116 of whom (54%) were diagnosed with heart failure (HF). Among these subjects, patients with HF were more likely to be older, to have a history of HF, to be in atrial fibrillation, and to have elevated troponin T concentrations compared with those without HF. In multivariate analysis, the use of loop diuretics on presentation (odds ratio [OR] 3.99, 95% confidence interval [CI] 1.58 to 10.1, p = 0.003), paroxysmal nocturnal dyspnea (OR 4.50, 95% CI 1.31 to 15.4, p = 0.02), jugular venous distention (OR 3.05, 95% CI = 1.06 to 8.79, p = 0.04), and the absence of cough (OR 0.18, 95% CI 0.06 to 0.52, p = 0.001) were associated with a diagnosis of acute HF in gray-zone patients. Subjects with HF and diagnostically elevated NT-pro-BNP concentrations had the highest mortality rates, subjects without HF and NT-pro-BNP concentrations < 300 ng/L had the lowest mortality rates, and subjects with gray-zone NT-pro-BNP had intermediate outcomes, irrespective of their final diagnoses. Adding specific clinical information to NT-pro-BNP improves diagnostic accuracy in subjects with intermediate NT-pro-BNP concentrations. Mortality rates in subjects with intermediate NT-pro-BNP concentrations are lower than in those with NT-pro-BNP concentrations diagnostic for HF but are higher than in subjects with NT-pro-BNP concentrations less than the gray zone.

A validated clinical and biochemical score for the diagnosis of acute heart failure: the ProBNP Investigation of Dyspnea in the Emergency Department (PRIDE) Acute Heart Failure Score

BACKGROUND

No method integrating amino-terminal pro-brain natriuretic peptide (NT-proBNP) testing with clinical assessment for the evaluation of patients with suspected acute heart failure (HF) has been described.

METHODS

Amino-terminal pro-brain natriuretic peptide results and clinical factors from 599 patients with dyspnea were analyzed. The beta coefficients of the 8 independent predictors of HF were used to assign a weighted integeric score for predictor. The sum of these integers provided a diagnostic HF "score" for each patient. Receiver operating characteristic curve analysis determined the optimal cut point for the diagnosis of acute HF. The performance of the score was evaluated in the development cohort and subsequently in a patient population from a separate clinical trial of patients with dyspnea conducted in Christchurch, New Zealand.

RESULTS

Eight factors comprised the score: elevated NT-proBNP (4 points), interstitial edema on chest x-ray (2 points), orthopnea (2 points), absence of fever (2 points), loop diuretic use, age > 75 years, rales, and absence of cough (all 1 point). Median scores in patients with acute HF were higher than those without acute HF (9 vs 3 points, P < .001). At a cut point of > or = 6 points, the score had a sensitivity of 96% and a specificity of 84% for the diagnosis of acute HF (P < .001). The score improved diagnostic accuracy over NT-proBNP testing alone and retained discriminative capacity in patients in whom clinical uncertainty was present. Lastly, the accuracy of the score was validated in the external data set of patients with suspected acute HF.

CONCLUSION

We report a simple and accurate scoring system combining NT-proBNP testing and clinical assessment for the diagnosis or exclusion of acute HF in patients with dyspnea.

Comparison of B-Type Natriuretic Peptides for Assessment of Cardiac Function and Prognosis in Stable Ischemic Heart Disease

In 1,049 patients with stable ischemic heart disease (IHD), brain natriuretic peptide (BNP) and amino terminal pro-brain natriuretic peptide (NTproBNP) correlated closely (r = 0.09, p < 0.001) and were similarly related to left ventricular ejection fraction (LVEF) (r = -0.50 and -0.46, respectively), age (0.44 and 0.47), and creatinine clearance (-0.51 and -0.51). Receiver-operating characteristic curves for detection of LVEF <30% were similar (area under the curves = 0.83 and 0.80, both p < 0.001), and both peptides had strong negative predictive value (95% and 94%). Both independently predicted all-cause mortality and/or heart failure with closely overlapping event-free survival curves; BNP and NTproBNP display strong, near-identical test performance in ruling about severely reduced LVEF and in prediction of all-cause mortality or heart failure in stable IHD.

OBJECTIVES

The aim of this work was to test B-type natriuretic peptides for assessment of function and prognosis in stable ischemic heart disease (IHD) and to compare brain natriuretic peptide (BNP) with amino terminal pro-brain natriuretic peptide (NTproBNP), including the relative effects of age and renal function on test performance.

BACKGROUND

Brain natriuretic peptide and NTproBNP are emerging diagnostic and prognostic markers in heart failure and acute coronary syndromes. Their performance in assessing function and prognosis in stable IHD is unknown. Whether one marker is superior and the relative effects of age and renal function on test performance are uncertain.

METHODS

In 1,049 patients with stable IHD, left ventricular ejection fraction (LVEF) was measured by radionuclide scanning and creatinine clearance estimated by the Cockroft-Gault equation. Age, gender, and body mass index were recorded. Twelve-month all-cause mortality or admission with heart failure was prospectively recorded; BNP and NTproBNP were measured by radioimmunoassay.

RESULTS

Brain natriuretic peptide and NTproBNP correlated closely (r = 0.90, p < 0.001) and had similar relationships to LVEF (r = -0.50 and -0.46, respectively, both p < 0.001), age (0.44 and 0.47, both p < 0.001), and creatinine clearance (-0.51 and -0.51, both p < 0.001). Areas under receiver-operating characteristic curves for detection of LVEF <30% were similar (0.83 and 0.80, both p < 0.001) with strong negative predictive values for both (95% and 94%). Both markers independently predicted the clinical end point with closely overlapping event-free survival curves.

CONCLUSIONS

In stable IHD, BNP and NTproBNP display strong and near-identical test performance in ruling out severely reduced LVEF and in prediction of all-cause mortality or heart failure despite significant effects of age, gender, and renal function on levels of both markers.

Effect of urocortin 1 infusion in humans with stable congestive cardiac failure

In sheep with HF (heart failure), Ucn1 (urocortin 1) decreases total peripheral resistance and left atrial pressure, and increases cardiac output in association with attenuation of vasopressor hormone systems and enhancement of renal function. In a previous study, we demonstrated in the first human studies that infusion of Ucn1 elevates corticotropin (‘ACTH’), cortisol and ANP (atrial natriuretic peptide), and suppresses the hunger-inducing hormone ghrelin in normal subjects. In the present study, we examined the effects of Ucn1 on pituitary, adrenal and cardiovascular systems in the first Ucn1 infusion study in human HF. In human HF, it is proposed that Ucn1 would augment corticotropin and cortisol release, suppress ghrelin and reproduce the cardiorenal effects seen in animals with HF. On day 3 of a controlled metabolic diet, we studied eight male volunteers with stable HF (ejection fraction <40%; New York Heart Association Class II–III) on two occasions, 2 weeks apart, receiving 50 μg of Ucn1 or placebo intravenously over 1 h in a randomized time-matched cross-over design. Neurohormones, haemodynamics and urine indices were recorded. Ucn1 infusion increased plasma Ucn1, corticotropin (baseline, 5.9±0.9 pmol/l; and peak, 7.2±1.0 pmol/l) and cortisol (baseline, 285±42 pmol/l; and peak, 310±41 pmol/l) compared with controls (P<0.001, 0.008 and 0.047 respectively). The plasma Ucn1 half-life was 54±3 min. ANP and ghrelin were unchanged, and no haemodynamic or renal effects were seen. In conclusion, a brief intravenous infusion of 50 μg of Ucn1 stimulates corticotropin and cortisol in male volunteers with stable HF.

Four-day urocortin-I administration has sustained beneficial haemodynamic, hormonal, and renal effects in experimental heart failure

AIMS

To investigate the subacute effects of a sustained intravenous infusion of urocortin-I (Ucn-I) in experimental heart failure (HF).

METHODS AND RESULTS

In eight sheep with pacing-induced HF, a 4-day infusion of Ucn-I (0.3 microg/kg/h) induced prompt (30 min) and sustained (4-day) increases in cardiac output (CO, Day 4: 1.8+/-0.2 vs. 2.3+/-0.2 L/min, P<0.001) and stroke volume (7.8+/-0.8 vs. 10.2+/-1.0 mL/beat, P=0.0011), and reductions in mean arterial pressure (MAP, 72+/-3 vs. 70+/-3 mmHg, P=0.0305), left atrial pressure (26+/-1 vs. 11+/-2 mmHg, P<0.001), and total calculated peripheral resistance (43+/-6 vs. 32+/-4 mmHg/L/min, P<0.001). Ucn-I also induced persistent falls in plasma renin (1.34+/-0.23 vs. 0.77+/-0.10 nmol/L/min, P=0.048), aldosterone (3273+/-1172 vs. 382+/-44 pmol/L, P=0.0098), endothelin-1 (4.6+/-0.3 vs. 2.7+/-0.3 pmol/L, P<0.001), vasopressin (24+/-4 vs. 14+/-2 pmol/L, P=0.0028) and atrial (184+/-14 vs. 154+/-29 pmol/L, P=0.0226) and brain (43+/-5 vs. 32+/-6 pmol/L, P=0.0016) natriuretic peptides. Plasma adrenocorticotrophic hormone and cortisol rose transiently on Day 0. Ucn-I enhanced urinary sodium excretion (5.3-fold, P=0.0001) and creatinine clearance (1.3-fold, P=0.0055) long-term, and tended to increase urine output (P=0.0748). Food intake was attenuated over the first 2 days of treatment (P=0.0283).

CONCLUSION

Four-day administration of Ucn-I induces sustained reductions in cardiac preload and MAP, improvements in CO and renal function, and inhibition of a range of vasoconstrictor/volume-retaining factors. These findings support Ucn-I's therapeutic potential in HF.

Endogenous urocortins reduce vascular tone and renin-aldosterone/endothelin activity in experimental heart failure

AIMS

To investigate the role of the endogenous urocortin peptides in heart failure (HF) through blockade of the corticotropin-releasing factor receptor 2 (CRF-R2).

METHODS AND RESULTS

Eight sheep were administered the CRF-R2 antagonist CRF(9-41) (1.5 mg bolus) before (Normal) and after development of pacing-induced HF. Compared with controls, CRF(9-41) in HF significantly increased mean arterial pressure (MAP) (71+/-2 vs. 75+/-2 mmHg, P=0.0024) and calculated total peripheral resistance (CTPR) (33.3+/-5.2 vs. 39.4+/-5.9 mmHg/L/min, P=0.0455). Similar trends were observed in the Normal state (MAP 87+/-1 vs. 89+/-2 mmHg, P=0.0689; CTPR 21.9+/-2.0 vs. 24.4+/-2.4 mmHg/L/min, P=0.0731). Left atrial pressure was elevated similarly in both states (Normal P=0.0013; HF P=0.0298), whereas cardiac output tended to be reduced (Normal P=0.0614). CRF(9-41) increased plasma urocortin-I (Normal 10.3+/-0.8 vs. 19.8+/-1.3 pmol/L, P<0.001; HF 14.4+/-0.9 vs. 25.3+/-0.8 pmol/L, P<0.001), renin (Normal 0.34+/-0.06 vs. 0.41+/-0.02 nmol/L/hr, P=0.013; HF 1.14+/-0.29 vs. 1.57+/-0.36 nmol/L/hr, P=0.0326), aldosterone (Normal 370+/-62 vs. 563+/-99 pmol/L, P=0.0813; HF 662+/-141 vs. 1024+/-209 pmol/L, P=0.095), and endothelin-1 (HF 3.18+/-0.18 vs. 4.74+/-1.04 pmol/L, P=0.0087). MAP, CTPR, renin, and endothelin-1 responses to CRF-R2 antagonism were significantly greater in HF than in the Normal state (P=0.049, 0.0427, 0.0311, and 0.0412, respectively).

CONCLUSION

These data suggest that the endogenous urocortin peptides contribute to the suppression of vascular tone and renin-angiotensin-aldosterone/endothelin activation in HF and thus, play a protective compensatory role in this disorder.

Clinical applications of B-type natriuretic peptides

Diagnostic, prognostic and therapeutic applications of B-type natriuretic peptides (NPs) will probably become part of routine management of heart failure within five years. Cardiac release of NPs rises with increasing cardiac dysfunction. Their secretion and plasma levels respond to intracardiac distending pressures, with other modulating influences including age, sex, renal function and other aspects of neurohormonal status. Single and serial plasma NP measurements, particularly of B-type and N-terminal pro-B-type NP, show promise in diagnosis of heart failure, risk stratification in those with known heart disease, and in adjustment of anti-failure therapy. Recombinant B-type NP is an effective parenteral treatment in decompensated heart failure. These applications of B-type NPs require confirmation before they become established in routine management of heart failure.

Urocortin-1 infusion in normal humans

Urocortin-1 (Ucn-1), a member of the corticotropin-releasing factor family, has been shown in animal studies to have effects on the pituitary-adrenal axis, the cardiovascular system, circulating neurohormones, and renal function and to suppress appetite. For the first time in man we have evaluated these effects of infused Ucn-1 as well as actions on plasma ghrelin, a hormone known to increase appetite. We also assessed Ucn-1 pharmacokinetics. Eight healthy male volunteers consuming a diet of constant sodium and potassium content received 50 micro g Ucn-1 iv over 1 h in a placebo-controlled, randomized, time-matched, cross-over study. Ucn-1 infusion compared with placebo increased plasma levels of corticotropin [44.6 +/- 7.7 vs. 19.1 +/- 3.2 pg/ml (9.5 +/- 1.7 vs. 4.2 +/- 0.7 pmol/liter); P < 0.001], cortisol [15.6 +/- 1.6 vs. 7.7 +/- 1.4 micro g/dl (432 +/- 43 vs. 213 +/- 40 nmol/liter); P < 0.001], and atrial natriuretic peptide [26.2 +/- 3.4 vs. 21.3 +/- 2.2 pg/ml [8.5 +/- 1.1 vs. 6.9 +/- 0.7 pmol/liter); P = 0.019] while suppressing plasma ghrelin (P = 0.008). No hemodynamic or renal effects were observed at the dose used. The plasma Ucn-1 t(1/2) was 52 min based on a one-compartment model. In conclusion, a brief iv infusion of 50 micro g Ucn-1 stimulates plasma ACTH, cortisol, and atrial natriuretic peptide secretion and suppresses plasma ghrelin in healthy male volunteers. The latter effect might contribute to the anorexic action of Ucn-1.

Vigorous response in plasma N-terminal pro-brain natriuretic peptide (NT-BNP) to acute myocardial infarction

Acute myocardial infarction (MI) results in activation of neurohormonal systems and increased plasma concentrations of myocardial enzymes and structural proteins. We hypothesized that plasma levels of N-terminal pro-brain natriuretic peptide (NT-BNP) would respond more vigorously after MI than those of other natriuretic peptides. We also sought to compare this response with that of the established myocardial injury markers troponin T (TnT), myoglobin and creatine kinase MB (CK-MB). We obtained multiple blood samples for measurement of atrial natriuretic peptide (ANP), N-terminal pro-ANP, brain natriuretic peptide (BNP) and NT-BNP along with CK-MB, TnT and myoglobin in 24 patients presenting to the Coronary Care Unit within 6 h of onset of MI. Multiple samples were obtained in the first 24 h, then at 72 h, 1 week, 6 weeks and 12 weeks. NT-BNP increased rapidly to peak at 24 h and exhibited greater ( P <0.001) absolute increments from baseline compared with BNP and ANP, whereas NT-ANP did not change from baseline. Proportional increments in NT-BNP were also greater than those for the other natriuretic peptides ( P <0.05). Natriuretic peptide levels reached their peak around 24 h, later than peak TnT, CK-MB and myoglobin (peak between 1-10 h), and NT-BNP and ANP remained elevated on average for 12 weeks. Our present results, with detailed sampling of a cohort of acute MI patients, demonstrate greater absolute and proportional increments in NT-BNP than ANP or BNP with sustained elevation of these peptides at 12 weeks.

Brain natriuretic peptide and n-terminal brain natriuretic peptide in the diagnosis of heart failure in patients with acute shortness of breath

OBJECTIVES

This study sought to compare the utility of measurement of plasma brain natriuretic peptide (BNP) and N-terminal brain natriuretic peptide (N-BNP) in the diagnosis of heart failure (HF) in patients with acute dyspnea.

BACKGROUND

Plasma BNP is useful in differentiating HF from other causes of dyspnea in the emergency department. The N-terminal component of BNP has a longer half-life, and in HF increases in plasma N-BNP are proportionately greater.

METHODS

We studied 205 patients (average age 70 +/- 14 years) presenting to the emergency department with acute dyspnea. Brain natriuretic peptide was analyzed using a point-of-care test and two locally developed radioimmunoassays. N-terminal BNP was measured using a locally developed radioimmunoassay and a commercially available assay. Final diagnosis of HF was adjudicated by two cardiologists.

RESULTS

Patients with HF (n = 70) had higher mean levels of both hormones by all assays (p < 0.001 for all). Results with all assays correlated closely (r values between 0.902 and 0.969). Subjects with left ventricular (LV) dysfunction or left-sided valvular disease but no HF had intermediate levels of BNP and N-BNP (lower than subjects with HF, and higher than subjects without HF with no LV dysfunction or left-sided valvular disease) (p < 0.01 for all). Using optimum cut-offs, specificity for the diagnosis of HF ranged between 70% and 89% (highest for the N-BNP assays). Sensitivity ranged between 80% and 94% (highest for the point-of-care BNP assay).

CONCLUSIONS

Measurement of BNP or N-BNP is useful in the diagnosis of HF in acute dyspnea. Commercially available assays compare favorably with well-validated laboratory assays. Differences in sensitivity and specificity may influence the assay choice in this setting.

B-type natriuretic peptides and ejection fraction for prognosis after myocardial infarction

BACKGROUND

A recent landmark report has demonstrated that plasma B-type natriuretic peptide (BNP) measured in acute coronary syndromes independently predicts mortality, heart failure, and new myocardial infarction. After acute cardiac injury, left ventricular ejection fraction (LVEF) is also of prognostic significance and plays a major role in determining the therapeutic response.

METHODS AND RESULTS

The present report is the first from a substantial (n=666) cohort of patients with acute myocardial infarction to test the prognostic utility of concurrent measurements of BNP, amino-terminal BNP (N-BNP), norepinephrine, and radionuclide LVEF. The B-type peptides and LVEF were predictors of death, heart failure, and new myocardial infarction (all P<0.001) independent of patient age, gender, previous myocardial infarction, antecedent hypertension or diabetes, previous heart failure, plasma norepinephrine, creatinine, cholesterol, drug therapy, and coronary revascularization procedures. The combination of N-BNP (or BNP) with LVEF substantially improved risk stratification beyond that provided by either alone. Elevated N-BNP (or BNP) predicted new myocardial infarction only in patients with LVEF <40%. LVEF <40% coupled to N-BNP over the group median conferred substantial 3-year risks of death, heart failure, and new myocardial infarction of 37%, 18%, and 26%, respectively. N-BNP and BNP were equivalent prognostic markers for these clinical outcomes.

CONCLUSIONS

Plasma N-BNP (or BNP) and LVEF are complementary independent predictors of major adverse events on follow-up after myocardial infarction. Combined measurement provides risk stratification substantially better than that provided by either alone.

Adrenomedullin and the renin-angiotensin-aldosterone system

Despite its positive inotropic effects and its propensity to stimulate the renin system, adrenomedullin (AM) is hypotensive as a result of dramatic reductions in peripheral resistance. Furthermore, it does not appear to increase aldosterone secretion in spite of often vigorous activation of circulating renin. Hence, we postulate that AM may act as a functional antagonist to angiotensin II both in the vasculature and the adrenal glomerulosa. In the series of studies performed in sheep and human (normal and circulatory disorders) reviewed here, we report significant hemodynamic and hormonal actions of AM. These actions include consistent reduction of arterial pressure associated with rises in cardiac output and hence a dramatic reduction in calculated total peripheral resistance (CTPR). AM also consistently attenuates the pressor effects of angiotensin II (but not norepinephrine). Furthermore, AM consistently increases plasma renin activity (PRA) and induces either a reduction in plasma aldosterone, dissociation between aldosterone/PRA ratio, or attenuation of angiotensin II-induced aldosterone secretion. Thus, these results clearly point to a role for AM in pressure and volume homeostasis acting, at least in part, by interaction with the renin-angiotensin-aldosterone system (RAAS).

Adrenomedullin and heart failure

Evidence suggests that adrenomedullin (AM) plays a role in the pathophysiology of heart failure. Circulating concentrations of AM are elevated in cardiovascular disease in proportion to the severity of cardiac and hemodynamic impairment. Raised plasma AM levels following acute cardiac injury and in heart failure provide prognostic information on adverse outcomes. In heart failure, elevated circulating AM also identifies patients likely to receive long-term benefit from inclusion of additional anti-failure therapy (carvedilol). Administration of AM in experimental and human heart failure induces reductions in arterial pressure and cardiac filling pressures, and improves cardiac output, in association with inhibition of plasma aldosterone (despite increased renin release) and sustained (or augmented) renal glomerular filtration and sodium excretion. Furthermore, AM in combination with other therapies (angiotensin-converting enzyme inhibition and augmentation of the natriuretic peptides) results in hemodynamic and renal benefits greater than those achieved by the agents separately. Manipulation of the AM system holds promise as a therapeutic strategy in cardiac disease.

Adrenomedullin in heart failure

Patients with heart failure have frequently been reported to show elevated levels of plasma adrenomedullin. These levels generally correlate with severity of hemodynamic dysfunction and also with neurohormonal indices which are activated according to the severity of heart failure. Furthermore, adrenomedullin gene expression in the heart and kidney is increased in experimental and clinical heart failure. A small number of studies have examined the responses to infusion of adrenomedullin in experimental and clinical heart failure. These studies have generally shown that infusion of adrenomedullin has beneficial hemodynamic effects and promotes maintenance or improvement in renal function, although most of these trials were of short duration. The available data suggest that adrenomedullin in the heart, kidney and plasma is increased in heart failure, possibly to counter the activation or actions of vasoconstricting and sodium-retaining hormone systems. An improved understanding of the role of adrenomedullin in heart failure might lead to the development of therapeutic agents acting through adrenomedullin receptors.

Beneficial hemodynamic, endocrine, and renal effects of urocortin in experimental heart failure: comparison with normal sheep

OBJECTIVES

The goal of this study was to determine the bioactivity of urocortin (Ucn) in experimental heart failure (HF).

BACKGROUND

Urocortin may participate in cardiovascular function and pressure/volume homeostasis. Its effects in HF are unknown.

METHODS

Eight normal sheep and eight sheep with pacing-induced HF received ovine Ucn (10, 50, and 100 mg intravenous boluses at 2-h intervals) in vehicle-controlled studies.

RESULTS

Urocortin boluses dose-dependently increased plasma Ucn (p < 0.001). Pharmacokinetics were similar in normal and HF sheep with half-lives approximating 1.3 and 19.5 h for the first and second phases, respectively. In HF, cardiac output increased (twofold), while peripheral resistance, left atrial pressure (both 50% falls: p < 0.001), and mean arterial pressure (p < 0.05) fell. In normal sheep, changes in peripheral resistance and atrial pressure were blunted and in arterial pressure were directionally opposite. Urocortin induced persistent, dose-dependent falls (30% to 50%) in plasma vasopressin, renin activity, aldosterone, natriuretic peptides (all p < 0.001), and endothelin-1 (p < 0.05) in HF sheep, while adrenocorticotrophic hormone and cortisol levels rose acutely (both p < 0.001). In comparison, Ucn in normal sheep resulted in a similar rise in cortisol and fall in aldosterone, no significant effects on plasma renin activity and natriuretic peptides, and a rise in vasopressin. Urocortin produced dose-dependent, sustained increases in urine volume (twofold, p < 0.01), sodium excretion (>9-fold rise, p < 0.001), and creatinine clearance (p < 0.001) in HF sheep. No significant renal effects were observed in normal sheep.

CONCLUSIONS

Urocortin has profound and sustained hemodynamic, hormonal, and renal effects in experimental HF. Urocortin may have a role in pressure/volume homeostasis in HF and may provide a novel therapeutic approach to this disease.

Diastolic heart failure in the community: clinical profile, natural history, therapy, and impact of proposed diagnostic criteria

BACKGROUND

Diastolic heart failure (DHF) has been broadly defined as "signs and symptoms of congestive heart failure (CHF) with normal/near normal systolic function." The clinical profile and natural history of the syndrome remain controversial. Furthermore, the frequency with which patients with CHF and normal ejection fraction (EF) fulfill recently proposed standardized diagnostic criteria for DHF is unclear. Our objective was to determine the clinical profile, Doppler echocardiographic features, current management, prognosis, and predictors of outcome of all patients with new onset CHF who had normal EF in Olmsted County, Minnesota, during 1996-1997. The frequency with which patients met recently proposed standardized criteria for diagnosis of DHF was assessed.

METHODS

Using the resources of the Rochester Epidemiology Project, all residents of Olmsted County, Minnesota, with a new diagnosis of CHF in 1996-1997, an ejection fraction >45%, and no valve disease (n = 83) were identified.

RESULTS

Patients were elderly (79 +/- 13 yr), predominantly female (76%), and had hypertension and/or coronary artery disease (85%). New-onset atrial fibrillation, ischemia, and medical comorbidities were frequently present at diagnosis. Although most patients (81%) met criteria for "probable DHF" by recently proposed clinical criteria, only half of patients met European criteria in which evidence of abnormal function/filling is required. The 1-, 2-, and 3-year mortality rates were 29%, 39%, and 60%, respectively. Angiotensin-converting enzyme inhibition (P =.0008) and beta-blocker (P =.02) therapy were independently associated with improved survival.

CONCLUSION

This population-based study provides a comprehensive clinical profile, current management, prognosis, and predictors of outcome of patients with new onset CHF who had normal ejection fraction.

Natriuretic peptide receptors and neutral endopeptidase in mediating the renal actions of a new therapeutic synthetic natriuretic peptide dendroaspis natriuretic peptide

OBJECTIVES

The objectives of the current study were to define for the first time the roles of the natriuretic peptide (NP) receptors and neutral endopeptidase (NEP) in mediating and modulating the renal actions of Dendroaspis natriuretic peptide (DNP), a new therapeutic synthetic NP.

BACKGROUND

Recent reports have advanced the therapeutic potential of a newly described synthetic NP called DNP. Dendroaspis natriuretic peptide is a 38-amino acid peptide recently isolated from the venom of Dendroaspis augusticeps (the green mamba snake).

METHODS

Synthetic DNP was administered intra-renally at 5 ng/kg/min to 11 normal anesthetized dogs, 5 of which received the NP receptor antagonist HS-142-1 (3 mg/kg intravenous bolus) while the remaining 6 dogs received an infusion of the NEP inhibitor, candoxatrilat (8 and 80 microg/kg/min) (Pfizer, Sandwich United Kingdom).

RESULTS

Intra-renal DNP resulted in marked natriuresis associated with increased urinary cyclic guanosine monophosphate excretion (UcGMPV), glomerular filtration rate (GFR), and renal blood flow (RBF) and decreased distal fractional sodium reabsorption (FNaR) compared with baseline. HS-142-1 attenuated the natriuretic response to DNP, resulting in decreased UcGMPV, GFR, and RBF and increased distal FNaR. In contrast, low and high doses of NEP inhibitor did not potentiate the renal actions of DNP.

CONCLUSIONS

We report that the NP receptor blockade attenuated the renal actions of synthetic DNP and that the NEP inhibitor did not alter the renal response to DNP. This latter finding is a unique property of synthetic DNP, as distinguished from other known NPs, supporting its potential as a therapeutic agent.

Plasma urotensin II in heart failure

Urotensin II has vasoconstrictive and negative inotropic effects, suggesting a possible role in circulatory regulation and pathophysiology of heart failure. We developed a sensitive specific RIA and measured plasma urotensin II in patients with heart failure and in controls. Plasma urotensin II was higher in heart failure patients (mean 3.9 pmol/L [SD 1.4]; than in controls (1.9 pmol/L [0.9]; p<0.0001). The role of urotensin II in heart failure, however, has yet to be defined.

BNP in hormone-guided treatment of heart failure

The pharmacotherapy of heart failure has become complex. Angiotensin-converting enzyme inhibitors (or angiotensin II receptor blockers), beta-blockers, spironolactone, diuretics and digoxin can be prescribed concurrently. Endothelin antagonists and combined inhibitors of converting enzyme and neutral endopeptidase are under investigation. Optimal dosing will become increasingly difficult to judge. Plasma brain natriuretic peptide (BNP) indicates the severity of left ventricular dysfunction. The C-terminal bioactive peptide and N-terminal BNP (N-BNP) circulate at concentrations related to cardiac status. We proposed that plasma levels of N-BNP would provide an index to guide drug treatment in established heart failure. Sixty-nine patients were randomized to treatment adjusted according to clinical criteria or plasma N-BNP. Hormone-guided therapy resulted in fewer clinical end points than did clinical management. This encourages further exploration of hormone guidance of anti-heart failure therapy, which could be extended to patients with preserved ejection fraction, in addition to those with established systolic dysfunction.

Antecedent hypertension and heart failure after myocardial infarction

OBJECTIVES

We sought to assess the relationship of antecedent hypertension to neurohormones, ventricular remodeling and clinical heart failure (HF) after myocardial infarction (MI).

BACKGROUND

Heart failure is a probable contributor to the increased mortality observed after MI in those with antecedent hypertension. Hence, neurohormonal activation, adverse ventricular remodeling and a higher incidence of clinical HF may be expected in this group. However, no previous report has documented serial postinfarction neurohumoral status, serial left ventricular imaging and clinical outcomes over prolonged follow-up in a broad spectrum of patients with and without antecedent hypertension.

METHODS

Inpatient events were documented in 1,093 consecutive patients (436 hypertensive and 657 normotensive) with acute MI. In 68% (282 hypertensive, 465 normotensive) serial neurohormonal sampling and radionuclide ventriculography were performed one to four days and three to five months after infarction. Clinical outcomes were recorded over a mean follow-up of two years.

RESULTS

Plasma neurohormones were significantly higher in hypertensives than in normotensives one to four days and three to five months after infarction. From similar initial values, left ventricular volumes increased significantly in hypertensives, compared with normotensives. Left ventricular ejection fraction rose significantly in normotensive but not hypertensive patients. Together with higher inpatient (8.1% vs. 4.4%, p < 0.002) and post-discharge mortality (9.5% vs. 5.5%, p = 0.043), hypertensive patients incurred more inpatient HF (33% vs. 24%, p < 0.001) and more late HF requiring readmission to hospital (12.4% vs. 5.5%, p < 0.001). Antecedent hypertension predicted late HF in patients >64 years of age with neurohormonal activation and early left ventricular dilation.

CONCLUSIONS

Antecedent hypertension interacts with age, neurohumoral activation and early ventricular remodeling to confer greater risk of HF after MI.

Actions of a novel synthetic natriuretic peptide on hemodynamics and ventricular function in the dog

Dendroaspis natriuretic peptide (DNP) is a recently discovered peptide with structural similarity to known natriuretic peptides. DNP has been shown to possess potent renal actions. Our objectives were to define the acute hemodynamic actions of DNP in normal anesthetized dogs and the acute effects of DNP on left ventricular (LV) function in conscious chronically instrumented dogs. In anesthetized dogs, DNP, but not placebo, decreased mean arterial pressure (141 +/- 6 to 109 +/- 7 mmHg, P < 0.05) and pulmonary capillary wedge pressure (5.8 +/- 0.3 to 3.4 +/- 0.2 mmHg, P < 0.05). Cardiac output decreased and systemic vascular resistance increased with DNP and placebo. DNP-like immunoreactivity and guanosine 3',5'-cyclic monophosphate concentration increased without changes in other natriuretic peptides. In conscious dogs, DNP decreased LV end-systolic pressure (120 +/- 7 to 102 +/- 6 mmHg, P < 0.05) and volume (32 +/- 6 to 28 +/- 6 ml, P < 0.05) and LV end-diastolic volume (38 +/- 5 to 31 +/- 4 ml, P < 0.05) but not arterial elastance. LV end-systolic elastance increased (6.1 +/- 0.7 to 7.4 +/- 0.6 mmHg/ml, P < 0.05), and Tau decreased (31 +/- 2 to 27 +/- 1 ms, P < 0.05). The effects on hemodynamics, LV function, and second messenger generation suggest synthetic DNP may have a role as a cardiac unloading and lusitropic peptide.

Maximizing the natriuretic peptide system in experimental heart failure: subcutaneous brain natriuretic peptide and acute vasopeptidase inhibition

BACKGROUND

A hallmark of congestive heart failure (CHF) is the elevation of the cardiac natriuretic peptides (NPs), which have natriuretic, renin-inhibiting, vasodilating, and lusitropic properties. We have reported that chronic subcutaneous (SQ) administration of brain natriuretic peptide (BNP) in experimental CHF improves cardiorenal function. Vasopeptidase inhibitors (VPIs) are single molecules that simultaneously inhibit both neutral endopeptidase 24.1 (NEP) and ACE. We hypothesized that acute VPI administration would potentiate the cardiorenal actions of SQ BNP in experimental CHF.

METHODS AND RESULTS

We determined the cardiorenal and humoral responses to acute VPI alone with omapatrilat (OMA) (1 micromol/kg IV bolus) (n=6), acute low-dose SQ BNP (5 microg/kg) alone (n=5), acute VPI plus low-dose SQ BNP (n=5), and acute high-dose SQ BNP (25 microg/kg) alone in 4 groups of anesthetized dogs with experimental CHF produced by ventricular pacing for 10 days. Plasma BNP was greater with VPI+low-dose SQ BNP compared with VPI alone or low-dose SQ BNP alone and was similar to high-dose SQ BNP alone. Urinary BNP excretion was greatest with VPI+SQ BNP. Urinary sodium excretion was also highest with VPI+SQ BNP, with the greatest increase in glomerular filtration rate. VPI+SQ BNP resulted in a greater increase in cardiac output and reduction in cardiac filling pressures as compared with low-dose SQ BNP, high-dose SQ BNP, or VPI alone.

CONCLUSIONS

This study reports that acute VPI potentiates the cardiorenal actions of SQ BNP in experimental CHF. This study advances the concept that protein therapy with BNP together with vasopeptide inhibition represents a novel therapeutic strategy in CHF to maximize the beneficial properties of the natriuretic peptide system.

Circulating natriuretic peptide concentrations in patients with end-stage renal disease: role of brain natriuretic peptide as a biomarker for ventricular remodeling

OBJECTIVES

To determine levels of natriuretic peptides (NPs) in patients with end-stage renal disease (ESRD) and to examine the relationship of these cardiovascular peptides to left ventricular hypertrophy (LVH) and to cardiac mortality.

PATIENTS AND METHODS

One hundred twelve dialysis patients without clinical evidence of congestive heart failure underwent plasma measurement of NP concentrations and echocardiographic investigation for left ventricular mass index (LVMI).

RESULTS

Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations correlated positively with LVMI and inversely with left ventricular ejection fraction, whereas C-type NP and Dendroaspis NP levels did not correlate with LVMI. In dialysis patients with LVH (LVMI >125 g/m2), plasma ANP and BNP concentrations were increased compared with those in dialysis patients without LVH (both P<001). In a subset of 15 dialysis patients without LVH or other concomitant diseases, plasma BNP concentrations were not significantly increased compared with those in 35 controls (mean +/- SD, 20.1+/-13.4 vs 13.5+/-9.6 pg/mL; P=.06), demonstrating that the BNP concentration was not increased by renal dysfunction alone. Furthermore, the BNP level was significantly higher in the 16 patients who died from cardiovascular causes compared with survivors (mean +/- SD, 129+/-13 vs 57+/-7 pg/mL; P<.003) and was significantly associated with greater risk of cardiovascular death in Cox regression analysis (P<.001), as was the ANP level (P=.002).

CONCLUSIONS

Elevation of the plasma BNP concentration is more specifically related to LVH compared with the other NP levels in patients with ESRD independent of congestive heart failure. Thus, BNP serves as an important plasma biomarker for ventricular hypertrophy in dialysis patients with ESRD.

Bioactivity of adrenomedullin and proadrenomedullin N-terminal 20 peptide in man

Although the biological effects of adrenomedullin (AM) and PAMP have been reported extensively in animal studies and from in-vitro experiments, relatively little information is available on responses to the hormone administered to man. This review summarizes data from the few studies carried out in man. In healthy volunteers, i.v. infusion of AM reduces arterial pressure, probably at a lower rate of administration than is required to elicit other responses. AM stimulates heart rate, cardiac output, plasma levels of cAMP, prolactin, norepinephrine and renin whilst inhibiting any concomitant response in plasma aldosterone. Little or no increase in urine volume or sodium excretion has been observed. Patients with essential hypertension differ only in showing a greater fall in arterial pressure and in the development of facial flushing and headache. In patients with heart failure or chronic renal failure, i.v. AM has similar effects to those seen in normal subjects but also induces a diuresis and natriuresis, depending on the dose administered. Infusion of AM into the brachial artery results in a dose-related increase in forearm and skin blood flow, more prominent and more dependent on endogenous nitric oxide in healthy volunteers than in patients with cardiac failure. When infused into a dorsal hand vein, AM partially reversed the venoconstrictor action of norepinephrine. Although much more information is required to clarify the role of AM under physiological and pathophysiological circumstances, it is clear that it has prominent hemodynamic and neurohormonal effects, though generally lesser urinary effects when administered short-term in doses sufficient to raise its levels in plasma to those seen in a number of clinical disorders. The only study of PAMP in man showed that its skeletal muscle vasodilator potency, when infused into the brachial artery of healthy volunteers, was less than one hundredth that of AM, and it was without effect on skin blood flow.

Brain natriuretic peptide-guided therapy for heart failure

The drug treatment of heart failure, once simple, has become complex. Apart from a loop diuretic and digoxin, most patients should now be receiving an angiotensin-converting enzyme inhibitor (or angiotensin II receptor blocker), a beta-blocker and spironolactone. Newer drugs, such as endothelin-receptor antagonists and combined blockers of converting-enzyme and neutral endopeptidase, might soon become available. When to introduce these drugs and what dose is optimal for any individual, are questions that currently vex clinicians. We proposed that plasma levels of the cardiac hormone brain natriuretic peptide (BNP, or better, its 1-76 amino-acid N-terminal fragment, N-BNP), would provide an objective index for guiding drug treatment in patients with established, stable cardiac failure. In a pilot study, 69 patients were randomized to drug treatment based on clinical criteria, or based on plasma levels of N-BNP. After a median follow-up of 9.6 months, those in the N-BNP group had fewer clinical end-points than those in the group managed by clinical criteria alone (19 vs 54; P= 0.02). These preliminary data encourage the concept that the increasingly complex pharmacotherapy for heart failure, both chronic (as in this trial) and acute, might best be guided by an objective measure such as plasma levels of BNP or N-BNP.

Endogenous natriuretic peptides participate in renal and humoral actions of acute vasopeptidase inhibition in experimental mild heart failure

Mild heart failure is characterized by increases in atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in the absence of activation of the renin-angiotensin-aldosterone system (RAAS). Vasopeptidase (VP) inhibitors are novel molecules that coinhibit neutral endopeptidase 24.11, which degrades the natriuretic peptides (NPs) and ACE. In a well-characterized canine model of mild heart failure produced by ventricular pacing at 180 bpm for 10 days, we defined the renal and humoral actions of acute VP inhibition with omapatrilat (OMA, n=6) and acute ACE inhibition (n=5) alone with fosinoprilat. We also sought to determine whether the NPs participate in the renal actions of acute VP inhibition by the administration of OMA together with an intrarenal administration of the NP receptor antagonist HS-142-1 (n=5). OMA resulted in a greater natriuretic response than did ACE inhibition in association with increases in plasma cGMP, ANP, BNP, urinary cGMP, urinary ANP excretion, and glomerular filtration rate (P<0.05 for OMA versus ACE inhibition). Plasma renin activity was increased only in the group subjected to ACE inhibition. Administration of intrarenal HS-142-1 attenuated the renal properties of OMA in association with a decrease in urinary cGMP excretion despite similar increases in plasma ANP and BNP. This study provides new insight into a unique new pharmacological agent that has beneficial renal actions in experimental mild heart failure beyond the actions that are observed with ACE inhibition alone and that are linked to the NP system.

Novel neurohumoral factors in congestive heart failure: adrenomedullin

Adrenomedullin is a 52-amino acid peptide that circulates in human plasma. The plasma concentrations of the peptide are increased in cardiovascular disease in proportion to the degree of hemodynamic impairment. Plasma adrenomedullin levels in heart failure, and in subjects with acute myocardial infarction, have been shown to convey independent prognostic information. Adrenomedullin has multiple biologic effects, but characteristically causes vasodilatation. The actions of adrenomedullin and the activation of this peptide in cardiovascular disease suggest it may have an important pathophysiologic role in heart failure. Manipulation of adrenomedullin or its receptor may have therapeutic potential.

Therapeutic actions of a new synthetic vasoactive and natriuretic peptide, dendroaspis natriuretic peptide, in experimental severe congestive heart failure

Dendroaspis natriuretic peptide (DNP), a recently discovered peptide, shares structural similarity to the other known natriuretic peptides, ANP, BNP, and CNP. Studies have reported that DNP is present in human and canine plasma and atrial myocardium and increased in plasma of humans with congestive heart failure (CHF). In addition, synthetic DNP is markedly natriuretic and diuretic and is a potent activator of cGMP in normal animals. To date, the ability of synthetic DNP to improve cardiorenal function in experimental CHF is unknown. Synthetic DNP was administered intravenously at 10 and 50 ng. kg(-1). min(-1) in dogs (n=7) with severe CHF induced by rapid ventricular pacing for 10 days at 245 bpm. In addition, we determined endogenous DNP in normal (n=4) and failing (n=4) canine atrial and ventricular myocardium. We report that administration of synthetic DNP in experimental severe CHF has beneficial cardiovascular, renal, and humoral properties. First, DNP in CHF decreased cardiac filling pressures, specifically right atrial pressure and pulmonary capillary wedge pressure. Second, DNP increased glomerular filtration rate in association with natriuresis and diuresis despite a reduction in mean arterial pressure. Third, DNP increased plasma and urinary cGMP and suppressed plasma renin activity. Fourth and finally, we report that DNP immunoreactivity is present in canine atrial and ventricular myocardium and increased in CHF. These studies report the acute intravenous actions of synthetic DNP in experimental severe CHF and suggest that on the basis of its beneficial properties, DNP may have potential as a new intravenous agent for the treatment of decompensated CHF.

Effects of adrenomedullin on load and myocardial performance in normal and heart-failure dogs

Myocardial actions of the vasodilator peptide adrenomedullin (ADM) in the intact animal are unknown. Negative and positive inotropic actions have been reported in ex vivo experiments. Myocardial and load-altering actions of ADM in dogs before and after development of heart failure were studied. With controlled heart rate (atrial pacing) and after beta-blockade, ADM was administered to five normal dogs in doses of 20 ng. kg(-1). min(-1) iv, 100 ng. kg(-1). min(-1) iv, and 200 ng. kg(-1). min(-1) into the left ventricle (LV). LV peak systolic pressure and end-systolic volume decreased with each dose of ADM. End-systolic pressure decreased with the two higher doses. At the highest dose, arterial elastance and the time constant of LV isovolumic relaxation (tau) decreased, and LV end-systolic elastance (E(es)) increased. LV end-diastolic pressure and volume were unchanged. In five additional normal dogs receiving only the highest dose of ADM (200 ng. kg(-1). min(-1) intra-LV), to control for increased heart rate and sympathetic activation observed with the cumulative infusion, ADM produced arterial vasodilation but no change in E(es) or tau. In four dogs with pacing-induced heart failure, ADM (200 ng. kg(-1). min(-1) intra-LV) was without effect on tau, E(es), and systolic or diastolic pressure and volume. In vivo, ADM appears to be a selective arterial dilator without inotropic or lusitropic effects. The vasodilatory actions are attenuated in heart failure.

Hemodynamic, hormonal, and renal effects of short-term adrenomedullin infusion in healthy volunteers

The actions of adrenomedullin (ADM), a 52-amino acid peptide, are not well defined in man. We, therefore, studied eight normal volunteers aged 1832 yr in a placebo-controlled crossover study. On the 2 study days, subjects received, in random order, ADM in "low" and "high" dose (2.9 pmol/kg x min and 5.8 pmol/kg x min for 2 h each) or vehicle (hemaccel) infusion on day 4 of a metabolic diet (Na+ 80 mmol/day, K+ 100 mmol/day). Achieved plasma ADM levels were in the pathophysiological range, and plasma cAMP values rose 5 pmol/L during the higher dose. Compared with time-matched vehicle infusion, high-dose ADM increased peak heart rate by 10 beats per minute (P < 0.05) and lowered diastolic (by 5 mm Hg, P < 0.01) blood pressure. Cardiac output increased in both phases of ADM (low dose, 7.6 L/min; high dose, 10.2 L/min; vehicle, 6 L/min; P < 0.05 for both). Despite a 2-fold rise in PRA during high-dose ADM (P < 0.01), aldosterone levels were unaltered. Norepinephrine levels increased by 50% during high-dose ADM (P < 0.001), but epinephrine levels were unchanged. Plasma PRL levels increased during high-dose ADM (P = 0.014). ADM had no significant effect on urine volume and sodium excretion. Infusion of ADM to achieve pathophysiological plasma levels produced significant hemodynamic effects, stimulated renin but inhibited the aldosterone response to endogenous angiotensin II, and activated the sympathetic system and PRL without altering urine sodium excretion in normal subjects.

Effects of natriuretic peptides on load and myocardial function in normal and heart failure dogs

The effects on myocardial function and loading conditions of clinically relevant doses of the natriuretic peptides (NP) have not been established. The actions of single doses (100 ng x kg(-1) x min(-1) iv over 30 min) of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) were studied in conscious normal dogs and in dogs with pacing-induced heart failure. All three NP reduced end-diastolic pressure in normal dogs, and ANP and BNP reduced end-diastolic volume. In heart failure ANP and BNP reduced EDP, and ANP reduced EDV. Arterial elastance was unchanged in normal dogs and in dogs with heart failure. ANP increased end-systolic elastance (E(es)) in normal dogs, whereas BNP tended to increase E(es) (P = 0.06). In dogs with heart failure, no inotropic effect was seen. In normal dogs, all NP reduced the time constant of isovolumic relaxation (tau), and ANP and BNP reduced tau in dogs with heart failure. Increases in plasma cGMP in dogs with heart failure were blunted. The NP reduced preload and enhanced systolic and diastolic function in normal dogs. Effects of ANP and BNP on preload and diastolic function were maintained in heart failure. Lack of negative inotropic effects in heart failure supports the validity of the NP as therapeutic agents.