S-nitrosohemoglobin deficiency: a mechanism for loss of physiological activity in banked blood.

RBCs distribute oxygen to tissues, but, paradoxically, blood transfusion does not always improve oxygen delivery and is associated with ischemic events. We hypothesized that storage of blood would result in loss of NO bioactivity, impairing RBC vasodilation and thus compromising blood flow, and that repleting NO bioactivity would restore RBC function. We report that S-nitrosohemoglobin (SNO-Hb) concentrations declined rapidly after storage of fresh venous blood and that hypoxic vasodilation by banked RBCs correlated strongly with the amounts of SNO-Hb (r(2) = 0.90; P < 0.0005). Renitrosylation of banked blood during storage increased the SNO-Hb content and restored its vasodilatory activity. In addition, canine coronary blood flow was greater during infusion of renitrosylated RBCs than during infusion of S-nitrosothiol-depleted RBCs, and this difference in coronary flow was accentuated by hypoxemia (P < 0.001). Our findings indicate that NO bioactivity is depleted in banked blood, impairing the vasodilatory response to hypoxia, and they suggest that SNO-Hb repletion may improve transfusion efficacy.

A nitric oxide processing defect of red blood cells created by hypoxia: deficiency of S-nitrosohemoglobin in pulmonary hypertension.

The mechanism by which hypoxia [low partial pressure of O(2) (pO(2))] elicits signaling to regulate pulmonary arterial pressure is incompletely understood. We considered the possibility that, in addition to its effects on smooth muscle, hypoxia may influence pulmonary vascular tone through an effect on RBCs. We report that exposure of native RBCs to sustained hypoxia is accompanied by a buildup of heme iron-nitrosyl (FeNO) species that are deficient in pO(2-)governed intramolecular transfer of NO to cysteine thiol, yielding a deficiency in the vasodilator S-nitrosohemoglobin (SNO-Hb). S-nitrosothiol (SNO)-deficient RBCs produce impaired vasodilator responses in vitro and exaggerated pulmonary vasoconstrictor responses in vivo and are defective in oxygenating the blood. RBCs from hypoxemic patients with elevated pulmonary arterial pressure (PAP) exhibit a similar FeNO/SNO imbalance and are thus deficient in pO(2)-coupled vasoregulation. Chemical restoration of SNO-Hb levels in both animals and patients restores the vasodilator activity of RBCs, and this activity is associated with improved oxygenation and lower PAPs.

Cutaneous findings in patients with pulmonary arterial hypertension receiving long-term epoprostenol therapy.

Pulmonary arterial hypertension (PAH) is a rare debilitating disease characterized by an increase in pulmonary vascular resistance and progressive right ventricular failure. PAH may be primary or associated with other conditions such as collagen vascular disease, portal hypertension, and HIV. Intravenous epoprostenol improves the survival, exercise tolerance, hemodynamics, and quality of life in patients with PAH and is believed to work through multiple pathways including vasodilation, opposition of smooth-muscle hypertrophy, and inhibition of platelet aggregation. Common dose-limiting side effects are flushing, jaw pain, arthralgias, myalgias, and headache, which are attributed to the vasodilatory effects of epoprostenol. In clinical practice, patients often develop persistent rash that is distinct from the flushing associated with epoprostenol. The specific findings both on physical examination and on dermatopathology have not, however, been well described. This report describes the cutaneous and dermatopathologic findings of 12 patients who developed persistent rash while receiving long-term prostacyclin for PAH.

Medical therapy for pulmonary arterial hypertension: ACCP evidence-based clinical practice guidelines.

Pulmonary arterial hypertension (PAH) is often difficult to diagnose and challenging to treat. Untreated, it is characterized by a progressive increase in pulmonary vascular resistance leading to right ventricular failure and death. The past decade has seen remarkable improvements in therapy, driven largely by the conduct of randomized controlled trials. Still, the selection of most appropriate therapy is complex, and requires familiarity with the disease process, evidence from treatment trials, complicated drug delivery systems, dosing regimens, side effects, and complications. This chapter will provide evidence-based treatment recommendations for physicians involved in the care of these complex patients. Due to the complexity of the diagnostic evaluation required, and the treatment options available, it is strongly recommended that consideration be given to referral of patients with PAH to a specialized center.

Pulmonary artery hypertension and sleep-disordered breathing: ACCP evidence-based clinical practice guidelines.

The objective of this article is to review the available data on the relationship between sleep-disordered breathing (SDB) and pulmonary arterial hypertension (PAH), with a focus on the prevalence of SDB in patients with idiopathic PAH (IPAH); the prevalence of PAH in patients with SDB; and the effects of SDB treatment on PAH. The evidence to date suggests that PAH may occur in the setting of SDB, although the prevalence is low. However, pulmonary hypertension (PH) in SDB is most strongly associated with other risk factors, such as left-sided heart disease, parenchymal lung disease, nocturnal desaturation, and obesity. The limited data available also suggest that SDB is uncommon in patients with IPAH. Treatment of SDB with continuous positive airway pressure may lower pulmonary artery pressures when the degree of PH is mild.

Electrocardiography to define clinical status in primary pulmonary hypertension and pulmonary arterial hypertension secondary to collagen vascular disease.

STUDY OBJECTIVES: To determine the utility of the ECG for predicting clinical status in adults with primary pulmonary hypertension (PPH) or pulmonary arterial hypertension (PAH) secondary to collagen vascular disease. DESIGN: Retrospective study. SETTING: Outpatient clinic in a tertiary referral center. PATIENTS: Adult outpatients with PPH or PAH secondary to collagen vascular disease who underwent electrocardiography within 30 days of undergoing right-heart catheterization, echocardiography, and 6-min walk testing. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The following measurements were recorded from each ECG: P-wave amplitude in lead II; mean frontal QRS axis; QRS duration; R-wave and S-wave deflections in leads I and V6; and the T-wave configurations in the precordial leads. These ECG variables were correlated with hemodynamic variables, RV size, and exercise capacity. Of the 61 patients included in this study, 56 (92%) were women. Eight of 61 patients (13%) had normal findings on ECGs. There was no significant difference in the demographics or hemodynamics when comparing groups with normal vs abnormal ECGs. All ECG parameters had no more than moderate correlation with hemodynamic variables, ventricular size measured by echocardiogram, and exercise capacity as measured by a 6-min walk. The best correlation was between mean the frontal QRS axis and cardiac index (r = -0.46). CONCLUSIONS: The ECG is an inadequate screening tool to rule out the presence of clinically relevant pulmonary hypertension, either primary or secondary to collagen vascular disease. The mean frontal QRS axis correlated best with the severity of hemodynamic impairment.

Severe erythroderma as a complication of continuous epoprostenol therapy.

Epoprostenol is a vasodilator that is produced by vascular endothelial cells and is currently the "gold standard" therapy for patients with severe primary pulmonary hypertension or pulmonary hypertension secondary to collagen vascular disease. Hypersensitivity to the drug has not been reported. We report a case of a patient with pulmonary hypertension and undifferentiated connective tissue disease who, after 2 months of treatment with epoprostenol, presented with rapidly progressive erythema, scaling, nausea and vomiting, and fever. Test results from a skin biopsy specimen were consistent with a drug reaction. The patient' condition improved after rapid tapering of her epoprostenol and administration of corticosteroids. Epoprostenol may be associated rarely with severe erythroderma.