Circulating surfactant protein-B levels increase acutely in response to exercise-induced left ventricular dysfunction.

1. As a result of its enormous surface area and necessary thinness for gas exchange, the alveolocapillary barrier is vulnerable to mechanical disruption from raised pulmonary microvascular pressure (Pmv). 2. Because surfactant protein-B (SP-B) leaks into the blood stream from the alveoli in response to alveolocapillary barrier damage and exercise leads to increased Pmv, we sought to determine whether exercise results in increased plasma SP-B. Moreover, in the setting of exercise-induced left ventricular dysfunction, the consequent increase in left heart filling pressure and, therefore, P(mv) would be expected to further increase plasma SP-B levels. 3. Twenty consecutive subjects referred for treadmill exercise stress echocardiography (ESE) had venous blood sampled immediately before and after ESE for batch atrial natriuretic peptide (ANP) and SP-B assay. Echocardiographic measures of pulmonary haemodynamics (pulmonary artery flow acceleration time (pafAT) and right ventricular outflow tract velocity time integral (rVTI)) were also taken pre- and post-exercise. 4. Although circulating ANP levels increased following exercise (P < 0.001), there was no change in circulating SP-B levels in the entire cohort. 5. Ten subjects had a positive ESE for ventricular dysfunction. Although circulating ANP was increased post-exercise in both the negative and positive ESE groups (P < 0.05 and P < 0.01, respectively), circulating SP-B only increased post-exercise in the positive ESE group (P < 0.05). Echocardiographic parameters supported an increment in P(mv) in the cohort with exercise-induced left ventricular dysfunction because this group had an increase in pafAT (P < 0.05; reflecting pulmonary artery pressure) and no change in rVTI. 6. Physical exertion associated with a Bruce protocol ESE is insufficient to increase circulating SP-B, despite evidence of increased left atrial and pulmonary vascular pressure. However, in the setting of exercise-induced myocardial dysfunction, there is a detectable increase in circulating SP-B. 7. The exaggerated increase in pulmonary vascular pressure in exercise-induced myocardial dysfunction may result in increased SP-B leakage from the alveoli into the circulation by altering the integrity of the alveolocapillary barrier to protein.

An international perspective on heart failure and left ventricular systolic dysfunction complicating myocardial infarction: the VALIANT registry.

AIMS: We analysed the contemporary incidence, outcomes, and predictors of heart failure (HF) and/or left ventricular systolic dysfunction (LVSD) before discharge in patients with acute myocardial infarction (MI). The baseline presence of HF or LVSD, or its development during hospitalisation, increases short- and long-term risk after MI, yet its incidence, predictors, and outcomes have not been well described in a large, international, general MI population. METHODS AND RESULTS: The VALIANT registry included 5573 consecutive MI patients at 84 hospitals in nine countries from 1999 to 2001. A multivariable logistic survival model was constructed using baseline variables to determine the adjusted mortality risk for those with in-hospital HF and/or LVSD. Baseline variables were also tested for associations with in-hospital HF and/or LVSD. Of the 5566 patients analysed, 42% had HF and/or LVSD during hospitalisation. Their in-hospital mortality rate was 13.0% compared with 2.3% for those without HF and/or without LVSD. After adjustment for other baseline risk factors, in-hospital HF and/or LVSD carried a hazard ratio for in-hospital mortality of 4.12 (95% confidence interval: 3.08-5.56). Patients with HF and/or LVSD also had disproportionately higher rates of other cardiovascular events. CONCLUSIONS: HF and/or LVSD is common in the general contemporary MI population and precedes 80.3% of all in-hospital deaths after MI. Survivors of early MI-associated HF and/or LVSD have more complications, longer hospitalisations, and are more likely to die during hospitalisation. Although baseline variables can identify MI patients at highest risk for HF and/or LVSD, such patients are less likely to receive indicated procedures and medical therapies.

Prolonged alveolocapillary barrier damage after acute cardiogenic pulmonary edema.

OBJECTIVES: To determine whether acute cardiogenic pulmonary edema is associated with damage to the alveolocapillary barrier, as evidenced by increased leakage of surfactant specific proteins into the circulation, to document the duration of alveolocapillary barrier damage in this setting, and to explore the role of pulmonary parenchymal inflammation by determining if circulating tumor necrosis factor-alpha is increased after acute cardiogenic pulmonary edema. DESIGN: Prospective, observational study. SETTING: Critical care, cardiac intensive care, and cardiology wards of a tertiary-care university teaching hospital. PATIENTS: A total of 28 patients presenting with acute cardiogenic pulmonary edema and 13 age-matched normal volunteers. INTERVENTIONS: Circulating surfactant protein-A and -B and tumor necrosis factor-alpha were measured on days 0 (presentation), 1, 3, 7, and 14. Clinical markers of pulmonary edema were documented at the same times. MEASUREMENTS AND MAIN RESULTS: Surfactant protein-A and -B were elevated on day 0 compared with controls (367 +/- 17 ng/mL vs. 303 +/- 17 and 3821 +/- 266 ng/mL vs. 2747 +/- 157 [mean +/- sem], p <.05), and although clinical, hemodynamic and radiographic variables improved rapidly (p <.001), surfactant protein-A and -B rose further until day 3 (437 +/- 22, p <.001, 4642 +/- 353, p <.01). Tumor necrosis factor-alpha was elevated at presentation (p <.05), doubled by day 1 (6.98 +/- 1.36 pg/mL, p <.05), remained elevated on day 3 (5.72 +/- 0.96 pg/mL, p <.05), and peak levels were related to chest radiograph extravascular lung water score (r(p) = 0.64, p =.003). CONCLUSIONS: Although the initial increase in plasma surfactant protein-A and -B may represent hydrostatic stress failure of the alveolocapillary barrier, the prolonged elevation, when hemodynamic abnormalities have resolved, and the delayed elevation of tumor necrosis factor-alpha are consistent with pulmonary parenchymal inflammation, which may further damage the alveolocapillary barrier. This prolonged physiologic defect at the alveolocapillary barrier after acute cardiogenic pulmonary edema may partly account for the vulnerability of these patients to recurrent pulmonary fluid accumulation.

Infarct-induced chronic heart failure increases bidirectional protein movement across the alveolocapillary barrier.

Chronic heart failure (CHF) is associated with adaptive structural changes at the alveolocapillary barrier that may be associated with altered protein permeability. Bidirectional protein movement across the barrier was studied in anesthetized rats with infarct-induced CHF by following (125)I-labeled albumin ((125)I-albumin) flux into the alveoli and the leakage of surfactant protein (SP)-B from the alveoli into the circulation. Three groups were studied: controls [0% left ventricular (LV) infarction], moderate infarct (25-45% LV infarction), and large infarct (>46% LV infarction). Wet and dry lung weights increased in the large infarct group (both P < 0.001), consistent with increased lung water and solid lung tissue. (125)I-albumin flux increased across the endothelial (P < 0.001) and epithelial (P < 0.01) components of the alveolocapillary barrier in the large infarct group. Plasma SP-B increased 23% with moderate infarcts (P < 0.05) and 97% with large infarcts (P < 0.001), independent of alveolar levels. Lavage fluid immune cells (P < 0.01) and myeloperoxidase activity (P < 0.05) increased in the large infarct group, consistent with inflammation. Bidirectional protein movement across the alveolocapillary barrier is increased in CHF, and alveolar inflammation may contribute to this pathophysiological defect.