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Biomedical subjects

R D Ross

Publications and source records attributed to R D Ross.

At least 37 records · Page 2Linked to original sources
PubMed1996

Idiopathic polypoidal choroidal vasculopathy associated with retinal arterial macroaneurysm and hypertensive retinopathy.

BACKGROUND: Idiopathic polypoidal choroidal vasculopathy (IPCV), the posterior uveal bleeding syndrome, and multiple recurrent serosanguineous pigment epithelial detachments in black women are a heterogeneous group of related entities seen in elderly hypertensive females. Similar associations are known for retinal arterial macroaneurysm (RAM). METHODS: This report documents the clinical, fluorescein, and indocyanine green videoangiographic findings of two elderly black female hypertensive patients who presented with IPCV, RAM, and hypertensive retinopathy. RESULTS: Clinical, fluorescein, and indocyanine green videoangiographic analysis of these two patients revealed hypertensive retinopathy, RAM, and anomalous polypoidal vascular networks associated with focal "bead-string" constrictions, terminal vascular loops, and polypoidal and pinpoint choroidal nodules. CONCLUSION: Certain subgroups of IPCV and related entities and RAM may be pathophysiologically related as analogous hypertensive insults to the choroidal and retinal vascular beds.

Aged↗
PubMed1996

The use of intravitreal tissue plasminogen activator in the treatment of experimental subretinal hemorrhage in the pig model.

PURPOSE: To clinically and surgically evaluate clot lysis in an animal model of subretinal hemorrhage after intravitreal injection of tissue plasminogen activator. METHODS: Autologous subretinal hemorrhages were created via a transvitreal approach in 18 pigs. The next day (day 1) animals were randomly selected to receive either an intravitreal injection of 0.1 mL balanced salt solution or 0.1 mL tissue plasminogen activator (25 micrograms) followed by observation or vitrectomy a day later. On day 2, six pigs (all treated with tissue plasminogen activator) underwent a vitrectomy in which aspiration of the subretinal hemorrhage was attempted. The other eyes were evaluated for clot lysis by ophthalmoscopy at days 3, 10, and 30. All eyes were examined histopathologically. RESULTS: The eyes that had been treated with tissue plasminogen activator demonstrated a color change at the peripheral margin, which suggested that clot lysis had occurred. At the time of the vitrectomy, the clots were liquefied partially; removal by aspiration alone, however, was not possible. Photoreceptor damage was moderate to severe by day 10 in all eyes, whether they were treated with tissue plasminogen activator or balanced salt solution. All eyes that underwent vitrectomy had moderate to severe photoreceptor damage. CONCLUSIONS: In this animal model, intravitreal tissue plasminogen activator was associated with features that suggested partial clot lysis; tissue plasminogen activator did not produce sufficient lysis to allow surgical removal by aspiration alone, however.

Animals↗
PubMed1995

Prenatal ultrasonographic diagnosis of ductus arteriosus aneurysm with spontaneous neonatal closure.

Aneurysm of the ductus arteriosus may be either spontaneous or acquired as a complication of surgical closure of a patent duct. Patients may be asymptomatic or present with a wide spectrum of symptoms, including hoarseness, respiratory symptoms, aortic or pulmonary thrombosis or embolism, or rupture of the aneurysm. We present the first report of prenatal ultrasonographic diagnosis of isolated ductus arteriosus aneurysm. The aneurysm presented at 39 weeks as an enlarged, dilated, vascular structure 15 mm in diameter, which began at the bifurcation of the main pulmonary artery and ended in the descending aorta. Doppler imaging demonstrated turbulent flow in this lesion. Following spontaneous delivery, a bidirectional shunt in the ductus arteriosus was found on the 1st day, but the caliber of the vessel was normal. An almost completely functionally closed ductus was found on the 2nd day. Spontaneous resolution of the lesion was confirmed by magnetic resonance imaging at 4 weeks of age.

Adult↗
PubMed1993

Relation of elevated plasma endothelin in congenital heart disease to increased pulmonary blood flow.

Endothelin-1 (ET), a potent vasoconstrictor peptide, has been found to be elevated in children with pulmonary hypertension associated with congenital heart defects. To evaluate the effect of pulmonary blood flow on ET concentrations, 5 ml blood samples were obtained peripherally at cardiac catheterization from 35 patients, ages 0.13 to 17 years (median 2). Plasma was extracted and ET measured by radioimmunoassay. Patients were classified into 2 groups based on the presence (group A) or absence (group B) of increased pulmonary blood flow defined as a Qp/Qs > or = 1.5. When the 13 patients (37%) in group A were compared with the 22 patients (63%) in group B there were no significant differences in age, cardiac index, or pulmonary and systemic resistances. ET concentrations were significantly higher in group A patients (median 3.25, range 0 to 16.5 vs median 0, range 0 to 6.35 pg/ml; p < or = 0.05). Pulmonary blood flow and pulmonary artery pressure were also higher in group A patients (p < or = 0.01). When patients within group A were subdivided into those with and without pulmonary hypertension, no difference was present in their ET concentrations (mean/SD: 4.4/4.3 vs 4.0/6.4 pg/ml, p = NS). Thus, ET is elevated in patients with congenital heart disease associated with left-to-right shunts and it appears that this increase is related to increased pulmonary blood flow independent of pulmonary artery pressure.

Adolescent↗
PubMed1993

Pediatric sedation: short-term effects.

A prospective investigation on the short-term effects of various sedation regimens on 549 nonhospitalized magnetic resonance (MR) patients was performed. The drugs evaluated were chloral hydrate, pentobarbital, midazolam, and diazepam (fentanyl was used for enhancement after any of these drugs). The overall safety and efficacy were quite good with all the regimens. Overall, 84% of children slept less than 8 h after the examination, 90% were drowsy and/or unsteady for less than 8 h after they awoke, and 97% resumed their usual activities by 24 h. Significant hyperactivity was seen only with pentobarbital and occurred in 8.4% of children over 8 years of age. The multiple-dose regimen of pentobarbital and fentanyl had a significant short-term effect on the children less than 8 years of age, with 35% sleeping longer than 8 h after the MR. Ten children who had needed the multiple-dose pentobarbital regimen or who had failed prior pentobarbital sedation presented for repeat sedation. Midazolam was effective in 9 of these 10 children.

Child, Preschool↗
PubMed1993

Acute changes in endothelin-1 after hemodialysis for chronic renal failure.

Endothelin is a recently described, potent renal vascular and systemic vasoconstrictor peptide. To evaluate the response of this peptide to volume contraction, we measured eight baseline and posthemodialysis samples from seven children, aged 14.5 +/- 3 years, with chronic renal failure. Plasma was extracted and endothelin-1 was measured by radioimmunoassay. Dialysis was performed for a 3- to 3 1/2-hour period, and body weight decreased from 38.0 +/- 14.3 to 36.2 +/- 13.8 kg (p < 0.01) during this time. There were no significant changes in heart rate or respiratory rate after dialysis, but blood pressure fell from 127/80 +/- 22/16 to 114/72 +/- 20/21 mm Hg (p = 0.05 for the systolic pressure). Plasma endothelin-1 concentration increased from 1.5 +/- 1.2 pg/ml at baseline to 7.3 +/- 8.9 pg/ml (p = 0.06) after dialysis; the fall in body weight from dialysis correlated with the increase in endothelin (r = -0.75; p = 0.05). Thus volume contraction from hemodialysis is associated with a rise in plasma endothelin-1, which is related to the acute change in body weight.

Adolescent↗
PubMed1992

Grading the severity of congestive heart failure in infants.

To determine which variables most accurately define congestive heart failure (CHF) in infants, 41 patients (median age 2.5 months) were graded by four pediatric cardiologists for the presence and severity of CHF based on the following variables: amount of formula consumed per feeding, feeding time, history of diaphoresis or tachypnea, growth parameters, respiratory and heart rates, respiratory pattern, perfusion, presence of edema, diastolic filling sounds, and hepatomegaly. There were 19 patients graded as having no CHF, nine as mild, seven moderate, and six severe CHF. The most sensitive and specific variables (p less than 0.0001) for the presence of CHF were a history of less than 3.5 oz/feed, respiratory rate greater than 50/min, an abnormal respiratory pattern, diastolic filling sounds, and hepatomegaly. Moderate to severe CHF was present when patients took less than 3 oz/feed or greater than 40 min/feed, had an abnormal respiratory pattern with a resting respiratory rate greater than 60/min, and had a diastolic filling sound and moderate hepatomegaly. Severe CHF was accompanied by a heart rate greater than 170/min, decreased perfusion, and severe hepatomegaly. Thus, the grading of the severity of CHF in infants should include an accurate description of these historical and clinical variables.

Heart↗
PubMed1992

Augmented norepinephrine and renin output in response to maximal exercise in hypertensive coarctectomy patients.

To evaluate a possible neural or renal contribution to the hypertension that occurs in some patients following coarctation of aorta repair, 35 patients underwent graded bicycle exercise with serial measurements of plasma norepinephrine concentrations and plasma renin activity. Sixteen patients with coarctectomy who had systolic or diastolic hypertension at peak exercise were compared with 19 normotensive patients with coarctectomy. The average time interval between coarctation repair and study was significantly longer (p less than 0.05) in the hypertensive group than in the normotensive patients (12.8 +/- 4.8 versus 8.7 +/- 2.2 years). The heart rate response to exercise was similar for both patient groups. The systolic blood pressure in the hypertensive group was higher than in the normotensive group at rest in the supine and upright positions and at 5 minutes of recovery, in addition to peak exercise, and the diastolic blood pressure was increased at peak exercise. Plasma norepinephrine concentrations were significantly higher at peak exercise and during recovery in the hypertensive group than in the normotensive patients. Plasma renin activity was also significantly higher in the hypertensive group at peak exercise. These data suggest that patients with coarctectomy who have a hypertensive response to exercise have an augmented sympathetic nervous system output and increased plasma renin activity that may lead to peripheral vasoconstriction at peak exercise and that may contribute to the development of their hypertension.

Adolescent↗
PubMed1990

Myocardial performance and perfusion during exercise in patients with coronary artery disease caused by Kawasaki disease.

For a study of the natural history of coronary artery lesions after Kawasaki disease and their effect on myocardial blood flow reserve with exercise, five such patients underwent exercise testing on a bicycle. Oxygen consumption, carbon dioxide production, minute ventilation, and electrocardiograms were monitored continuously. Thallium-201 scintigraphy was performed for all patients. One patient stopped exercise before exhaustion of cardiovascular reserve but had no evidence of myocardial perfusion abnormalities. Four patients terminated exercise because of exhaustion of cardiovascular reserve; one had normal cardiovascular reserve and thallium scintiscans, but the remaining patients had diminished cardiovascular reserve. Thallium scintigrams showed myocardial ischemia in two and infarction in one. No patient had exercise-induced electrocardiographic changes. These results indicate that patients with residual coronary artery lesions after Kawasaki disease frequently have reduced cardiovascular reserve during exercise. The addition of thallium scintigraphy and metabolic measurements to exercise testing improved the detection of exercise-induced abnormalities of myocardial perfusion.

Adolescent↗
PubMed1988

Determinants of plasma atrial natriuretic factor concentrations in congenital heart disease.

Seventeen children with congenital heart disease undergoing elective cardiac catheterization were studied to define potential hemodynamic and echocardiographic determinants of plasma atrial natriuretic factor (ANF) concentrations. ANF concentrations in the right ventricle and femoral vein were measured by radioimmunoassay. Right ventricular levels were significantly higher than femoral venous levels (p less than 0.01), but the correlation between the 2 was high (r = 0.87, p less than 0.001). Stepwise multiple linear regression analysis demonstrated that right ventricular ANF concentrations were predicted by a combination of indexed right atrial area measured by 2-dimensional echocardiography, right atrial pressure, pulmonary resistance and heart rate (multiple r2 = 0.83). Femoral venous ANF concentrations were predicted by indexed right atrial area and systolic pulmonary artery pressure (multiple r2= 0.79). It was concluded that there are significant independent predictors of right ventricular and femoral venous plasma ANF concentrations in children with congenital heart disease. The right atrial area indexed by body surface area was the only significant predictor of both central and peripheral plasma ANF concentrations in the multivariate analysis.

Atrial Natriuretic Factor↗
PubMed1987

Plasma norepinephrine levels in infants and children with congestive heart failure.

To characterize the sympathetic nervous system response to congestive heart failure (CHF) in infants and children, plasma catecholamine levels were measured in 102 subjects undergoing routine cardiac catheterization (mean age 3.3 years, range 0.1 to 14.7), including 61 with left-to-right shunts. Plasma norepinephrine levels were significantly higher (p less than 0.0001) in children with CHF than in those without CHF. A highly significant association (p less than 0.0001) was found between the level of plasma norepinephrine and severity of CHF symptoms. This relation was found for CHF secondary to lesions producing a left-to-right shunt and CHF resulting from primary myocardial dysfunction. In congenital lesions with a left-to-right shunt, plasma norepinephrine levels correlated well with size of the shunt (Qp/Qs) (r = 0.75, p less than 0.001) and degree of pulmonary arterial hypertension (r = 0.70, p less than 0.001). Elevation of plasma norepinephrine concentrations in infants and children are seen with severe CHF regardless of its origin.

Adolescent↗