Search PubMed⌕ Search

Biomedical subjects

R J Barst

Publications and source records attributed to R J Barst.

68 records · Page 4Linked to original sources
PubMed1989

The pharmacological treatment of patent ductus arteriosus. A review of the evidence.

Modern heart surgery began with operative intervention for patent ductus arteriosus in 1938. Half a century later, ligation and division of patent ductus arteriosus in an infant or child remains a simple and safe surgical procedure for a lesion identified relatively easily. In the intervening years, paediatric cardiologists and surgeons have also directed their attention to the management of more complex congenital cardiac defects. Recently, however, there has been a significant reappraisal and re-emphasis of the role of patent ductus arteriosus in the context of neonatal cardiopulmonary disease. Interest has focused on: (a) surgical and pharmacological management of the premature infant with a large ductal left-to-right shunt in the context of respiratory distress syndrome; (b) preservation of patency in ductal-dependent congenital heart disease; and (c) ductal right-to-left shunting in persistence of the fetal circulation (PFC) syndrome or other diseases associated with increased pulmonary vascular resistance. This review examines the above conditions and reviews the progress and current status of drug therapy in the treatment of these disorders. Closure of the ductus arteriosus with cyclo-oxygenase inhibition as well as re-opening and maintaining patency of the ductus arteriosus with prostaglandin therapy is discussed.

Ductus Arteriosus, Patent↗
PubMed1989

Isolated pulmonary hypertension in the grandchild of a kindred with scleroderma (systemic sclerosis): "neonatal scleroderma"?

We report a small kindred in which the father and daughter with positive antinuclear antibodies (ANA) (proband) had diffuse cutaneous and visceral scleroderma (systemic sclerosis, SSc), antitopoisomerase autoantibodies and shared the HLA-A23 C- B- DR5 DRw52 DQw3 haplotype. The ANA- granddaughter (daughter of the proband) was noted to have severe isolated pulmonary hypertension within the first 6 months of life, and had the other maternal HLA-A1 Cw8 B14 DR1 DQw1 haplotype, which included a B1, B2 duplication of the C4B allele. All 3 members shared DRw52. The possibility that neonatal pulmonary hypertension represents an isolated autoimmune disease or a hitherto undescribed neonatal syndrome is proposed and the immunogenetic autoantibody implications are discussed.

Antibodies, Antinuclear↗
PubMed1986

Pharmacologically induced pulmonary vasodilatation in children and young adults with primary pulmonary hypertension.

To evaluate pulmonary vasoreactivity in children and young adults with primary pulmonary hypertension, we performed cardiac catheterizations on nine patients with primary pulmonary hypertension (nine months to 23 years old) and made hemodynamic measurements: before and after infusing prostacyclin, and before and after administering sublingual nifedipine. Based upon the response to prostacyclin, patients were divided into responders and nonresponders using the following criteria: 20 percent or greater decrease in mean pulmonary arterial pressure; an increase in cardiac index; and no change, or a decrease in the pulmonary vascular resistance to systemic vascular resistance ratio. By these criteria, five of the nine patients had a reactive pulmonary vascular bed and responded to prostacyclin administration. In addition, they all responded to nifedipine. The remaining four did not respond to either drug. There was a close correlation (r = 0.85, p less than 0.01) between the magnitude of the pulmonary vasodilator response to treatment with prostacyclin and nifedipine. There was also a significant inverse correlation between the age of the patient at the time of the study and the pulmonary vasodilator response to administration of prostacyclin (r = 0.91, p less than 0.01) and nifedipine (r = 0.82, p less than 0.01); ie, both drugs produced a greater fall in pulmonary arterial pressure in younger patients with primary pulmonary hypertension than in older ones.

Adolescent↗
PubMed1985

"Bedside" balloon septostomy in infants with transposition of the great arteries: new concepts using two-dimensional echocardiographic techniques.

We performed balloon atrial septostomies in six successive infants with transposition of the great arteries, using echocardiographic guidance at the bedside in the neonatal intensive care unit. In all cases adequate septostomy was obtained and instantaneously assessable. PaO2 values increased as expected (mean before septostomy 28 mm Hg; after, 42 mm Hg). In cases of transposition clearly diagnosed echocardiographically, this intervention need not be done in the catheterization laboratory. The need for a full hemodynamic study in the neonatal period is arguable.

Cardiac Catheterization↗
PubMed1985

Relation of arachidonate metabolites to abnormal control of the pulmonary circulation in a child.

To evaluate the role of arachidonate metabolites in regulating pulmonary vascular tone, we performed multiple studies on a 17-month-old girl with idiopathic pulmonary hypertension, systemic arterial hypoxemia (due to ventilation-perfusion mismatching), and an elevated thromboxane A2 (TXA2) to prostacyclin (PGI2) ratio due to increased TXA2 (measured as their stable metabolites, TXB2 and 6-keto-PGF1 alpha, respectively). Intravenous infusions of PGI2 reduced mean pulmonary arterial pressure (from 80 to 47 mmHg), increased cardiac output (from 3.43 to 3.97 L/min), increased systemic arterial oxygen saturation (from 60 to 72 percent), and decreased the TXB2 to 6-keto-PGF1 alpha ratio (from 5.9 to 0.2); mean systemic arterial pressure was unchanged. Pharmacologically decreasing the TXB2 to 6-keto-PGF1 alpha ratio with administration of nifedipine or diltiazem also reduced pulmonary hypertension and increased systemic arterial oxygen saturation in this patient. Nifedipine and diltiazem decreased the ratio by decreasing TXB2. Prostacyclin decreased the ratio by increasing 6-keto-PGF1 alpha. These studies support the hypothesis that the balance between TXA2 and PGI2 is an important influence on pulmonary vascular tone.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Endothelial function in clinical pulmonary hypertension.

The endothelium regulates the concentrations of several types of vasoactive substances that affect pulmonary vascular tone, and endothelia can oppose vasoconstriction in some circumstances by releasing vasodilators. To assess some of these endothelial functions in patients with pulmonary hypertension, we made measurements of selected vasoactive substances before and during attempts at pharmacologic vasodilatation. Studies were performed in 16 patients (1 1/2 to 23 years of age) with either idiopathic pulmonary hypertension (n = 11) or pulmonary hypertension as a consequence of unexpected early pulmonary vascular disease accompanying congenital heart defects (n = 5). In six of ten children, norepinephrine levels were elevated, and in two of the six, the concentrations of norepinephrine were greater in the aorta than in the pulmonary artery. In four out of 16 patients, thromboxane levels were increased, and in three of the four, the concentrations of thromboxane were greater in the aorta than in the pulmonary artery. These concentration gradients suggest pulmonary release of these vasoconstrictors. Identification of the contribution to pulmonary vasoconstriction made by changes in the endothelial metabolism of vasoactive substances may lead to a more fundamental understanding of the control of the pulmonary circulation, and hence lead to more specific modes of therapy for pulmonary hypertension.

Adolescent↗
PubMed1985

Sarcoidosis and reactive pulmonary hypertension.

Despite diffuse disease of the lungs (often with widespread inflammation or obliteration of blood vessels) in sarcoidosis, pulmonary hypertension is uncommon, occurring in 1% to 4% of cases. We report a case of sarcoidosis and severe pulmonary hypertension that, in striking contrast to other reports, occurred in the absence of obliterative pulmonary vascular disease. We therefore examined the possibility of whether an abnormality in pulmonary vascular tone might be a cause of the pulmonary hypertension. In pharmacologic studies, we demonstrated pulmonary vasodilatation and, in response to increased pulmonary blood flow, the elaboration of the pulmonary vasoconstricting eicosanoid, thromboxane.

Adult↗
PubMed1981

Aspergillus endocarditis in children: case report and review of the literature.

Aspergillus fumigatus endocarditis developed in a 2 1/2-year-old girl after repair of tetralogy of Fallot. There have been 14 other cases of Aspergillus endocarditis in children described in the literature. Fever and embolic phenomenon, particularly to the CNS, were the most common presenting manifestations. Consumptive coagulopathy developed in this patient as it has in other children and should suggest the diagnosis of Aspergillus endocarditis inasmuch as blood cultures are uniformly negative. Antemortem diagnosis was made in four of 15 patients. Only one patient survived the infection. Environmental surveillance is crucial when a case is encountered. Survival of the infected patient occurs only with early diagnosis and surgical removal of the infected tissue.

Aspergillosis↗
PubMedDate not supplied

Pulmonary atresia and ventricular septal defect with coronary artery to pulmonary artery fistula: case report and review of the literature.

The pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect is highly variable. Several cases have been reported in the literature in which a coronary artery to pulmonary artery fistula, alone or in combination with additional vessels, supplies the pulmonary circulation. We report a case of successful repair during early infancy, with unique hemodynamic, clinical, and anatomic features. The literature is reviewed.

Arterio-Arterial Fistula↗
PubMedDate not supplied

Exercise testing in children with primary pulmonary hypertension.

Cardiopulmonary exercise testing is a useful noninvasive tool to assess physiological changes associated with exercise. Developing noninvasive methods to assess the severity of cardiopulmonary disorders, as well as the response to therapeutic interventions, is useful in conditions, such as primary pulmonary hypertension, in which invasive procedures carry significant risks. The 6-minute walk test is a simple measure of exercise endurance. Exercise studies that measure both hemodynamic and ventilatory responses provide additional information regarding the interaction of the circulatory and pulmonary systems. Subtle changes in exercise capacity may suggest deterioration prior to clinical manifestations. This may lead to an earlier reevaluation, including repeat cardiac catheterization, and subsequently changes in medical and/or surgical therapy.

Child↗
PubMedDate not supplied

Feasibility of a two-dimensional echocardiographic method for the clinical assessment of right ventricular volume and function in children.

The relative ease of acquisition and safety of two-dimensional echocardiography has established it as the mainstay for routine cardiac imaging. Translation of imaging data into useful quantitative information, however, requires fitting the ventricle to a specific geometric model. Because of its complex shape and anterior position, many attempts at right ventricular quantitation by two-dimensional echocardiography have been criticized as impractical and not reproducible. A simple method incorporating subcostal and apical imaging was introduced in 1984. This approach appeared to combine accuracy and practicability but was never validated in a clinical setting because of the difficulties of subcostal imaging in adults. This study assessed the feasibility and accuracy of this technique in the pediatric population. Results of volume comparison to values derived by magnetic resonance imaging were r = 0.96, standard error of the estimate (SEE) = 19.3 ml, and mean difference = 15 +/- 19.4 ml and r = 0.97, SEE = 12.3 ml, and bias = 5 +/- 11.8 ml for diastolic and systolic volumes, respectively. Comparison of estimates of ejection fraction with magnetic resonance imaging demonstrated r = 0.90, SEE = 5.9%, and bias = 3% +/- 5.7%. Interobserver and intraobserver variability was 9.9% and 8.2%, respectively, for systolic volumes and 11.5% and 8.9%, respectively, for diastolic volumes. Evaluation of right ventricular size and function by this approach is comparable to determinations by magnetic resonance imaging and may be clinically useful in the management of pediatric patients.

Adolescent↗
PubMedDate not supplied

Delivery of intravenous treprostinil at low infusion rates using a miniaturized infusion pump in patients with pulmonary arterial hypertension.

PURPOSE: Treprostinil is approved for the treatment of pulmonary arterial hypertension (PAH) via continuous intravenous (IV) infusion. Treprostinil's anti-platelet aggregation characteristics and stability at room temperature may allow for low infusion rates (0.1-0.2 mL/hr) using a miniaturized infusion pump. METHODS: A 12-week, multi-center, open-label study in 12 adult PAH patients, evaluated the feasibility and safety of low-flow IV treprostinil administration via the 407C miniaturized pump. Patients receiving IV treprostinil at a stable dose were transitioned from their current CADD-Legacy pump to the 407C and were assessed for adverse events including catheter occlusions, pump alarms, and efficacy (six minute walk distance (6MWD), Borg Dyspnea Score (BDS), NYHA functional class, and PAH signs/symptoms). All patients were also maintained on therapeutic doses of warfarin, heparin or low molecular weight heparin throughout the study. RESULTS: Baseline mean (+/-SD) 6MWD was 477 +/- 76 m (n = 9) with mean BDS of 2.1 +/- 1.2 (n = 9). Week 12 mean 6MWD and BDS were 500 +/- 92 m and 2.3 +/- 1.7, respectively (n = 9). Four patients discontinued the study prematurely (3 AEs and 1 consent withdrawn). Adverse events included headache, flushing, and nausea. Pump complications occurred in 5 of 12 patients, and although no catheter occlusions occurred in any patient during the 12-week study, further study is needed regarding pump complications. CONCLUSION: This study demonstrates that treprostinil can be administered intravenously at infusion rates as low as 0.1 mL/hr for 12 weeks without catheter occlusions. Further studies are warranted because the potential for adverse events is of some concern.

Adult↗