Impact of 4D-Flow CMR Parameters on Functional Evaluation of Fontan Circulation.

We sought to evaluate the potential clinical role of 4D-flow cardiac magnetic resonance (CMR)-derived energetics and flow parameters in a cohort of patients' post-Fontan palliation. In patients with Fontan circulation who underwent 4D-Flow CMR, streamlines distribution was evaluated, as well a 4D-flow CMR-derived energetics parameters as kinetic energy (KE) and energy loss (EL) normalized by volume. EL/KE index as a marker of flow efficiency was also calculated. Cardiopulmonary exercise test (CPET) was also performed in a subgroup of patients. The population study included 55 patients (mean age 22 ± 11 years). The analysis of the streamlines revealed a preferential distribution of the right superior vena cava flow for the right pulmonary artery (62.5 ± 35.4%) and a mild preferential flow for the left pulmonary artery (52.3 ± 40.6%) of the inferior vena cave-pulmonary arteries (IVC-PA) conduit. Patients with heart failure (HF) presented lower IVC/PA-conduit flow (0.75 ± 0.5 vs 1.3 ± 0.5 l/min/m2, p = 0.004) and a higher mean flow-jet angle of the IVC-PA conduit (39.2 ± 22.8 vs 15.2 ± 8.9, p < 0.001) than the remaining patients. EL/KE index correlates inversely with VO2/kg/min: R: - 0.45, p = 0.01 peak, minute ventilation (VE) R: - 0.466, p < 0.01, maximal voluntary ventilation: R:0.44, p = 0.001 and positively with the physiological dead space to the tidal volume ratio (VD/VT) peak: R: 0.58, p < 0.01. From our data, lower blood flow in IVC/PA conduit and eccentric flow was associated with HF whereas higher EL/KE index was associated with reduced functional capacity and impaired lung function. Larger studies are needed to confirm our results and to further improve the prognostic role of the 4D-Flow CMR in this challenging population.

Implementation of the Care Bundle for the Management of Chronic Obstructive Pulmonary Disease with/without Heart Failure.

Chronic obstructive pulmonary disease (COPD) is often part of a more complex cardiopulmonary disease, especially in older patients. The differential diagnosis of the acute exacerbation of COPD and/or heart failure (HF) in emergency settings is challenging due to their frequent coexistence and symptom overlap. Both conditions have a detrimental impact on each other's prognosis, leading to increased mortality rates. The timely diagnosis and treatment of COPD and coexisting factors like left ventricular overload or HF in inpatient and outpatient care can improve prognosis, quality of life, and long-term outcomes, helping to avoid exacerbations and hospitalization, which increase future exacerbation risk. This work aims to address existing gaps, providing management recommendations for COPD with/without HF, particularly when both conditions coexist. During virtual meetings, a panel of experts (the authors) discussed and reached a consensus on the differential and paired diagnosis of COPD and HF, providing suggestions for risk stratification, accurate diagnosis, and appropriate therapy for inpatients and outpatients. They emphasize that when COPD and HF are concomitant, both conditions should receive adequate treatment and that recommended HF treatments are not contraindicated in COPD and have favorable effects. Accurate diagnosis and therapy is crucial for effective treatment, reducing hospital readmissions and associated costs. The management considerations discussed in this study can potentially be extended to address other cardiopulmonary challenges frequently encountered by COPD patients.

Contribution of the Lung to the Genesis of Cheyne-Stokes Respiration in Heart Failure: Plant Gain Beyond Chemoreflex Gain and Circulation Time.

Background The contribution of the lung or the plant gain ( PG ; ie, change in blood gases per unit change in ventilation) to Cheyne-Stokes respiration ( CSR ) in heart failure has only been hypothesized by mathematical models, but never been directly evaluated. Methods and Results Twenty patients with systolic heart failure (age, 72.4±6.4 years; left ventricular ejection fraction, 31.5±5.8%), 10 with relevant CSR (24-hour apnea-hypopnea index [ AHI ] ≥10 events/h) and 10 without ( AHI <10 events/h) at 24-hour cardiorespiratory monitoring underwent evaluation of chemoreflex gain (CG) to hypoxia ([Formula: see text]) and hypercapnia ([Formula: see text]) by rebreathing technique, lung-to-finger circulation time, and PG assessment through a visual system. PG test was feasible and reproducible (intraclass correlation coefficient, 0.98; 95% CI , 0.91-0.99); the best-fitting curve to express the PG was a hyperbola ( R2≥0.98). Patients with CSR showed increased PG , [Formula: see text] (but not [Formula: see text]), and lung-to-finger circulation time, compared with patients without CSR (all P<0.05). PG was the only predictor of the daytime AHI ( R=0.56, P=0.01) and together with the [Formula: see text] also predicted the nighttime AHI ( R=0.81, P=0.0003) and the 24-hour AHI ( R=0.71, P=0.001). Lung-to-finger circulation time was the only predictor of CSR cycle length ( R=0.82, P=0.00006). Conclusions PG is a powerful contributor of CSR and should be evaluated together with the CG and circulation time to individualize treatments aimed at stabilizing breathing in heart failure.

Pharmacological approach and adherence to treatment recommendations in frequently and non-frequently exacerbating COPD patients from Italy: MISTRAL - The prospective cohort, observational study.

BACKGROUND: Several documents and guidelines provide recommendations for effective management of COPD patients. However, there is often a significant imbalance between recommended treatment of COPD patients and the actual care provided both in primary care and specialty setting. This imbalance could result in a significant negative impact on patients' health status and quality of life, leading to increased hospitalisations and health resource utilisation in COPD patients METHODS: MISTRAL was an observational, longitudinal, prospective cohort study, designed to assess the overall pharmacological approach of COPD in routine clinical practice in Italy. Eligible patients were divided into two cohorts based on their exacerbation history in the year prior to the enrolment, frequent exacerbators (FEs; ≥2 exacerbations), and non-frequent exacerbators (NFEs; ≤1 exacerbation). The primary objective was to assess adherence to Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2011 treatment recommendations in FEs and NFEs at baseline and follow-up visits RESULTS: Of the 1489 enrolled patients, 1468 (98.6%; FEs, 526; NFEs, 942) were considered evaluable for analyses. At baseline, 57.8% of patients were treated according to GOLD 2011 recommendations; a greater proportion of FEs were treated according to GOLD recommendations, compared with NFEs patients at baseline (77.1% versus 46.7%; P < 0.0001), and all study visits. At baseline, GOLD group D patients were the most adherent (81.2%) to treatment recommendations, while group A patients were the least adherent (30.3%) at baseline, attributed mainly to overuse of inhaled corticosteroids in less severe GOLD groups. Triple therapy with long-acting muscarinic antagonist (LAMA) + long-acting ß2-agonist/inhaled corticosteroid (LABA/ICS) was the most frequent prescribed treatment at all study visits, irrespective of patient's exacerbation history. Changes in treatment were more frequent in FEs versus NFEs CONCLUSIONS: The Mistral study reports a scarce adherence to the GOLD 2011 treatment recommendations in routine clinical practice in Italy. The adherence was particularly low in less severe, non-frequent exacerbating patients mostly for ICS overuse, and was higher in high-risk, frequent exacerbating COPD patients.

Respiratory Training Late After Fontan Intervention: Impact on Cardiorespiratory Performance.

Fontan palliation allows patients with "single ventricle" circulation to reach adulthood with an acceptable quality of life, although exercise tolerance is significantly reduced. To assess whether controlled respiratory training (CRT) increases cardiorespiratory performance. 16 Adolescent Fontan patients (age 17. 5 ± 3.8 years) were enrolled. Patients were divided into CRT group (n = 10) and control group (C group, n = 6). Maximal cardiopulmonary test (CPT) was repeated at the end of CRT in the CRT group and after an average time of 3 months in the C group. In the CRT group a CPT endurance was also performed before and after CRT. In the CRT group there was a significant improvement in cardiovascular and respiratory response to exercise after CRT. Actually, after accounting for baseline values, the CRT group had decreased breathing respiratory reserve (- 15, 95% CI -22.3 to - 8.0, p = 0.001) and increased RR peak (+ 4.8, 95% CI 0.7-8.9, p = 0.03), VE peak (+ 13.7, 95% CI 5.6-21.7, p = 0.004), VO2 of predicted (+ 8.5, 95% CI 0.1-17.0, p = 0.05), VO2 peak (+ 4.3, 95% CI 0.3 to 8.2, p = 0.04), and VO2 workslope (+ 1.7, 95% CI 0.3-3.1, p = 0.02) as compared to the control group. Moreover, exercise endurance time increased from 8.45 to 17.7 min (p = 0.01). CRT improves cardiorespiratory performance in post-Fontan patients leading to a better aerobic capacity.

Ventilatory response to exercise of elite soccer players.

BACKGROUND: The purpose of this study was to evaluate the role of ventilatory parameters in maximal exercise performance in elite soccer players. METHODS: From September 2009 to December 2012, 90 elite soccer players underwent evaluation of lung function test and ergospirometry by means of an incremental symptom-limited treadmill test. Results were analyzed according to i) maximal exercise velocity performed (Hi-M: high-performers, >18.65 km/h; Lo-M: low-performers, <18.65 km/h) and ii) usual role in the team. RESULTS: Hi-M showed higher peak minute ventilation (V˙Epeak: 158.3 ± 19.5 vs 148.0 ± 18.54 L/min, p = 0.0203), and forced expiratory volume at first second (5.28 ± 0.50 vs 4.89 ± 0.52 liters, p < 0.001) than Lo-M, independently of playing role. Moreover, a significant correlation between peak oxygen uptake and V˙E (r = 0.57, p < 0.001) was found. CONCLUSIONS: Ventilatory response plays a role in the assessment of exercise capacity in elite soccer players.

Improved survival in limited scleroderma-related pulmonary artery hypertension.

Reportedly, patients with scleroderma-related pulmonary hypertension (SSc-PAH) respond poorly to new vasoactive drugs (NVD). Forty-nine SSc-PAH patients underwent right heart catheterization (RHC) and, according to NVD availability, divided as follows: Group 1 (n = 23, from 1999 to 2004, poor availability), and Group 2 (n = 26, from 2005 to 2010, good availability). Before diagnostic RHC, NVD had been given to 30 % of the patients in Group 1, and 58 % of those in Group 2 (p = 0.049). At diagnosis, patients in Group 1 had greater heart dilatation (p < 0.01), higher mean pulmonary artery pressure (p < 0.05), lower pulmonary artery capacitance (p < 0.05), and lower carbon monoxide lung diffusing capacity (DLco, p < 0.05) than those in Group 2. At a median follow-up time of 15.5 months, DLco further decreased in Group 1 (p < 0.05), whereas cardiac index increased in Group 2 (p < 0.05). At 36 months of follow-up, 72.4 % of the patients in Group 2 were still alive as opposed to 30.4 % in Group 1 (p = 0.02). In multivariate analysis, DLco and mixed venous oxygen saturation (SvO2) were independent predictors of survival. A value of DLco <7.2 mL/mmHg/min was associated with a hazard ratio (HR) of 5.3 (p < 0.001); for SvO2 <63.8 %, the HR was 3.7 (p < 0.01).NVD have beneficial effects in patients with SSc-PAH. Both DLco and SvO2 are predictors of survival and may assist in planning treatment.

Effects of emphysema on oxygen uptake during maximal exercise in COPD.

The objective of the study is to assess the effects of emphysema on peak oxygen uptake ([Formula: see text]) during a cardiopulmonary exercise test in patients with chronic obstructive pulmonary disease (COPD). We measured [Formula: see text] and oxygen pulse in 80 patients with stable COPD exercising maximally. Oxygen saturation was measured by pulse oximetry (SpO(2)), and the ventilatory response assessed by the ratio of tidal volume (V (T)) at peak to slow vital capacity (SVC) at baseline, and by the percent increase of peak V (T) over baseline. Computed tomography imaging (CT scan) served as the reference diagnostic standard for emphysema. Based on the panel-grading (PG) method, emphysema was rated absent or mild (PG ≤ 30, n = 54), or moderate to severe (PG > 30, n = 26). Multiple quantile regression was applied to estimate the effects of PG > 30 on [Formula: see text]. At peak exercise, the patients with PG > 30 had significantly lower [Formula: see text], oxygen pulse and SpO(2), and featured a blunted ventilatory response with respect to those with PG ≤ 30 (p < 0.001). With multiple quantile regression, the effects of PG > 30 on [Formula: see text] were only partially explained by the degree of lung hyperinflation, a substantial component being imputable to impairment of lung diffusing capacity. In conclusion, chronic obstructive pulmonary disease patients with moderate to severe emphysema feature significantly lower exercise tolerance than those with no or mild emphysema. Our findings underscore the need of tailoring therapeutic interventions for COPD to the predominant clinical phenotype to improve exercise capacity.

Improved survival in patients with inoperable chronic thromboembolic pulmonary hypertension.

Patients with inoperable chronic thromboembolic pulmonary hypertension (Inop-CTEPH) treated with conventional therapy have a poor survival. We compare the 3-year survival between those treated with conventional therapy and those treated with conventional therapy and a combination of novel drugs. We also evaluate the clinical course. A total of 34 Inop-CTEPH consecutive patients were evaluated from 1991 to 2009 including right heart catheterization (RHC) and perfusion lung scan (PLS): 7 underwent surgical treatment while 27 were confirmed inoperable. Of these 27 patients, 12 evaluated from 1991 to 2003 (Group 1) were treated with conventional therapy and 15 evaluated from 2004 to 2009 (Group 2) were treated with conventional and novel therapies. At baseline, no group difference emerged at RHC. Based on clinical course, novel drugs and oxygen supplementation were given to patients of Group 2. Seven of these who had worse clinical course repeated RHC and four of them also PLS during therapy. Those without repeat RHC had baseline pulmonary artery mean pressure and brain natriuretic peptide (NT-proBNP) lower and mixed venous saturation (SvO2) and exercise test higher (p = 0.022, 0.015, 0.044 and 0.003, respectively). During therapy, those with repeat RHC had total pulmonary vascular resistance reduced (p = 0.012), base excess increased (p = 0.002) and significant redistribution of pulmonary blood flow at PLS. At the 3-year follow-up, survival was 86% in Group 2 and 31% in Group 1 (p = 0.031). In Inop-CTEPH patients, the clinical course may help to select drugs and the level of oxygen supply that can improve hemodynamics, gas exchange and long-term survival.

Routine Chest X-ray: Still Valuable for the Assessment of Left Ventricular Size and Function in the Era of Super Machines?

OBJECTIVES: The development of technologically advanced, expensive techniques has progressively reduced the value of chest X-ray in clinical practice for the assessment of left ventricular (LV) dilatation and dysfunction. Although controversial data are reported on the role of this widely available technique in cardiac assessment, it is known that the cardio-thoracic ratio is predictive of risk of progression in the NYHA Class, hospitalization, and outcome in patients with LV dysfunction. This study aimed to evaluate the reliability of the transverse diameter of heart shadow [TDH] by chest X-ray for detecting LV dilatation and dysfunction as compared to Magnetic Resonance Imaging (MRI) performed for different clinical reasons. MATERIALS AND METHODS: In 101 patients, TDH was measured in digital chest X-ray and LV volumes and ejection fraction (EF) by MRI, both exams performed within 2 days. RESULTS: A direct correlation between TDH and end-diastolic volumes (r = .75, P<0.0001) was reported. TDH cut-off values of 14.5 mm in females identified LV end-diastolic volumes >150 mL (sensitivity: 82%, specificity: 69%); in males a cut-off value of 15.5 mm identified LV end-diastolic volumes >210 mL (sensitivity: 84%; specificity: 72%). A negative relation was found between TDH and LVEF (r = -.54, P<0.0001). The above cut-off values of TDH discriminated patients with LV systolic dysfunction - LVEF <35% (sensitivity and specificity: 67% and 57% in females; 76% and 59% in males, respectively). CONCLUSIONS: Chest X-ray may still be considered a reliable technique in predicting LV dilatation by the accurate measurement of TDH as compared to cardiac MRI. Technologically advanced, expensive, and less available imaging techniques should be performed on the basis of sound clinical requests.

Abnormal hyperventilation in patients with hepatic cirrhosis: role of enhanced chemosensitivity to carbon dioxide.

BACKGROUND: Patients with hepatic cirrhosis frequently show idiopathic hyperventilation at rest, despite no concomitant cardiopulmonary disease. The aim of the study was to determine whether altered chemosensitivity either to hypoxia or hypercapnia could underlie inappropriate hyperventilation in cirrhotic patients. METHODS: We consecutively recruited 30 biopsy proven cirrhotic patients equally distributed in the three Child's classes A, B and C (age 54 ± 8 years, mean ± SD). All patients underwent evaluation of chemosensitivity to hypoxia and to hypercapnia and blood sampling for brain natriuretic peptide, norepinephrine and progesterone, besides full clinical characterization. We also recruited 10 age- and gender-matched healthy controls (age 55 ± 7 years). RESULTS: Overall, 18 patients (60%) showed an increased chemosensitivity to carbon dioxide (CO(2)), while 8 patients (27%) showed enhanced chemosensitivity to hypoxia. Child's class C patients had lower arterial partial pressure of CO(2) (PaCO(2)), higher rest ventilation, increased chemosensitivity to hypercapnia, plasma level of norepinephrine and serum progesterone levels when compared to class A patients and controls (all p < 0.05). Rest ventilation was positively related to pH (R = 0.41, p = 0.023), chemosensitivity to hypercapnia (R = 0.54, p = 0.002), and progesterone (R = 0.53, p = 0.016) and negatively to PaCO(2) (R = 0.61, p < 0.001), but not to hemoglobin level and chemosensitivity to hypoxia. Chemosensitivity to hypercapnia was positively related to PaCO(2) (R = 0.74, p < 0.001), serum progesterone (R = 0.50, p = 0.016), and to plasma norepinephrine (R = 0.57, p = 0.004). CONCLUSIONS: Enhanced chemosensitivity to hypercapnia was found in more decompensated cirrhotic patients and was associated with sympathetic overactivity and elevated serum progesterone, likely representing a key mechanism underlying the "unexplained" hyperventilation observed in such patients.

Early subclinical increase in pulmonary water content in athletes performing sustained heavy exercise at sea level: ultrasound lung comet-tail evidence.

Whether prolonged strenuous exercise performed by athletes at sea level can produce interstitial pulmonary edema is under debate. Chest sonography allows to estimate extravascular lung water, creating ultrasound lung comet-tail (ULC) artifacts. The aim of the study was to determine whether pulmonary water content increases in Ironmen (n = 31) during race at sea level and its correlation with cardiopulmonary function and systemic proinflammatory and cardiac biohumoral markers. A multiple factor analysis approach was used to determine the relations between systemic modifications and ULCs by assessing correlations among variables and groups of variables showing significant pre-post changes. All athletes were asymptomatic for cough and dyspnea at rest and after the race. Immediately after the race, a score of more than five comet tail artifacts, the threshold for a significant detection, was present in 23 athletes (74%; 16.3 ± 11.2; P < 0.01 ULC after the race vs. rest) but decreased 12 h after the end of the race (13 athletes; 42%; 6.3 ± 8.0; P < 0.01 vs. soon after the race). Multiple factor analysis showed significant correlations between ULCs and cardiac-related variables and NH(2)-terminal pro-brain natriuretic peptide. Healthy athletes developed subclinical increase in pulmonary water content immediately after an Ironman race at sea level, as shown by the increased number of ULCs related to cardiac changes occurring during exercise. Hemodynamic changes are one of several potential factors contributing to the mechanisms of ULCs.

Pulmonary edema in healthy subjects in extreme conditions.

There are several pieces of evidence showing occurrence of pulmonary edema (PE) in healthy subjects in extreme conditions consisting of extreme psychophysical demand in normal environment and psychophysical performances in extreme environment. A combination of different mechanisms, such as mechanical, hemodynamic, biochemical, and hypoxemic ones, may underlie PE leading to an increase in lung vascular hydrostatic pressure and lung vascular permeability and/or a downregulation of the alveolar fluid reabsorption pathways. PE can be functionally detected by closing volume measurement and lung diffusing capacity test to different gases or directly visualized by multiple imaging techniques. Among them chest ultrasonography can detect and quantify the extravascular lung water, creating "comet-tail" ultrasound artefacts (ULCs) from water-thickened pulmonary interlobular septa. In this paper the physiopathological mechanisms of PE, the functional and imaging techniques applied to detect and quantify the phenomenon, and three models of extreme conditions, that is, ironman athletes, climbers and breath-hold divers, are described.

Innovative model to simulate exhalation phase in human respiratory system.

In this paper, we present a mathematical model, which mimics the bronchial resistances of human's lung in an expiratory act. The model is implemented in Matlab. The inputs that are used in this model derive from spirometry test. This model is able to study a physiologic condition, a pathologic one and the patient's follow up after drug treatment. We split our study into two parts. The first one focuses the analysis on the gas fluido dynamic inside of the respiratory pathways. The second part takes care of the pressure equilibrium in the exchange zone. We use the outputs that derive from the second subsystem to solve the Bernoulli's equation of the first part. The model was validated with data provided from "Clinical Physiology Institute" of CNR and G. Monasterio Foundation of Pisa.

Comparison of NT-proCNP and CNP plasma levels in heart failure, diabetes and cirrhosis patients.

C-type natriuretic peptide (CNP) plasma levels are extremely low and a pre-analytical phase is necessary to assay plasma CNP concentrations. Amino-terminal CNP (NT-proCNP) circulates at higher concentrations than CNP, allowing a direct assay and the use of smaller amounts of plasma. Aim of this study was to evaluate the analytical performance of a direct NT-proCNP assay and to measure its plasma levels in heart failure (CHF), diabetes and chirrosis patients. NT-proCNP and CNP were measured in 130 CHF, 19 patients with diabetes, 24 with hepatic cirrhosis and 73 controls. Plasma NT-proCNP was higher in all the clinical conditions studied (controls:45.5 ± 1.84 pg/ml, CHF:67.09 ± 7.36, diabetes:51.5 ± 5.75 cirrhosis:78.4 ± 19.9; p = 0.034, p = 0.04 controls vs. CHF and cirrhosis, respectively) and in CHF NT-proCNP concentration showed a significant increase as a function of clinical severity. By comparison of ROC curves, CNP assay resulted better associated with disease than NT-proCNP assay in all the different clinical conditions probably due to different release and clearance. The determination of NT-proCNP adds a piece of information to better understanding the molecular mechanisms at the basis of CNP action in different diseases. Due to its higher analytical feasibility, this determination could become widespread in clinical biochemistry laboratories and serve as a complementary marker of disease conditions.

Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test.

BACKGROUND: Alveolar volume measured according to the American Thoracic Society-European Respiratory Society (ATS-ERS) guidelines during the single breath diffusion test can be underestimated when there is maldistribution of ventilation. Therefore, the alveolar volume calculated by taking into account the ATS-ERS guidelines was compared to the alveolar volume measured from sequentiallly collected samples of the expired volume in two groups of individuals: COPD patients and healthy individuals. The aim of this study was to investigate the effects of the maldistribution of ventilation on the real estimate of alveolar volume and to evaluate some indicators suggestive of the presence of maldistribution of ventilation. METHODS: Thirty healthy individuals and fifty patients with moderate-severe COPD were studied. The alveolar volume was measured either according to the ATS-ERS guidelines or considering the whole expired volume subdivided into five quintiles. An index reflecting the non-uniformity of the distribution of ventilation was then derived (DeltaVA/VE). RESULTS: Significant differences were found when comparing the two measurements and the alveolar volume by quintiles appeared to have increased progressively towards residual volume in healthy individuals and much more in COPD patients. Therefore, DeltaVA/VE resulted in an abnormal increase in COPD. CONCLUSION: The results of our study suggest that the alveolar volume during the single breath diffusion test should be measured through the collection of a sample of expired volume which could be more representative of the overall gas composition, especially in the presence of uneven distribution of ventilation. Further studies aimed at clarifying the final effects of this way of calculating the alveolar volume on the measure of DLCO are needed. DeltaVA/VE is an index that can help assess the severity of inhomogeneity in COPD patients.

Radioimmunoassay for plasma C-type natriuretic peptide determination: a methodological evaluation.

C-Type natriuretic peptide (CNP) is a member of the family of natriuretic peptides with vasodilatory properties, and is produced and secreted by endothelial cells. It seems to play a central role in the paracrine vasomotor control of tone and to be important in several clinical conditions characterized by endothelial dysfunction. We evaluated the analytical performance of a commercially available radioimmunoassay for CNP after a preliminary extraction with Sep-Pak C18. Its analytical reliability was checked by determination of CNP plasma levels in healthy subjects (n = 23) and in patients with different diseases, likely characterized by endothelial dysfunction, such as chronic heart failure (n = 133) and cirrhosis (n = 84). The extraction yield was 78+/-3%. Accuracy of the radiommunological determination was evaluated by dilution (45-370 microL of extracted plasma) and recovery tests (>80%). Between- and within-assay variabilities were < or = 10% and analytical sensitivity was 0.41+/-0.015 pg/tube. Plasma CNP in patients with chronic heart failure and with cirrhosis was significantly raised compared to controls (p<0.0001 and p = 0.001, respectively). The sensitivity, accuracy and variability levels of the method proposed for CNP assay was suitable for reliable detection of changes in CNP plasma levels in the clinical setting.