Regional differences in retinal vascular reactivity.
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PURPOSE: Although glaucomatous visual field defects are more common in the superior field than in the inferior field, microaneurysms are more frequent in the superior than in the inferior retina in diabetic retinopathy. The authors hypothesized that differences in vascular hemodynamics in the two areas might contribute to these phenomena. METHODS: The blood flow response to hyperoxia and hypercapnia was evaluated in peripapillary retinal tissue superior and inferior to the optic nerve head using confocal scanning laser Doppler flowmetry. In 14 young, healthy persons, blood flow was measured while breathing room air and during isocapnic hyperoxia (100% O2 breathing) and isoxic hypercapnia (PCO2 increased 15% above baseline). Histograms were generated from pixel-by-pixel analysis of retinal portions of superior and inferior temporal quadrants of the entire image. RESULTS: Baseline blood flow in the inferior temporal quadrant was significantly greater than in the superior temporal quadrant (P < 0.05). However, the inferior region failed to increase in perfusion during hypercapnia and experienced significant mean blood flow reduction; flow reduction in the pixels at the 25th, 50th, 75th, and 90th percentile of flow; and an increased percentage of pixels without measurable flow, during hyperoxia (each P < 0.05). In contrast, in the superior temporal region, hyperoxia failed to reduce blood volume, velocity, or flow, whereas hypercapnia significantly increased mean flow; increased flow in the pixels at the 25th, 50th, 75th, and 90th percentile of flow; and reduced the percentage of pixels without measurable flow (each P < 0.05). CONCLUSIONS: The inferior temporal quadrant of the peripapillary retina is, in comparison with the superior temporas region, less responsive to vasodilation and more responsive to vasoconstriction. These differences could contribute to different susceptibility to visual field defect or vascular dysfunction in the superior and inferior retina. (+info)
Respiratory distress due to tracheal compression by the dilated innominate artery.
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The case reported is of an 88 yr old female with hypertension and respiratory distress. A chest radiograph revealed a widening of the upper mediastinum. Computed tomographic scanning revealed tracheal compression by the innominate artery, which was elongated and curved. After intubation, she was treated with antihypertensive drugs. This resulted in the remarkable recovery of the patient from respiratory distress. To the authors' knowledge, this is the first reported case of respiratory distress owing to tracheal compression by elongation and curvature of the innominate artery. (+info)
Exercise-induced myocardial ischemia in isolated coronary artery ectasias and aneurysms ("dilated coronopathy").
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OBJECTIVES: The purpose of our study was to evaluate the clinical significance of isolated coronary artery ectasias or aneurysms (CEA). BACKGROUND: It has been postulated that altered coronary blood flow in CEA predisposes patients to the development of myocardial ischemia (CI) and infarction. METHODS: Sixty-seven patients with bilateral nonobstructive CEA without associated cardiac defects ("dilated coronaropathy") were derived from 16,341 cardiac catheterizations between 1986 and 1997. Ectasias were defined as luminal dilation of 1.5- to 2.0-fold, aneurysms of >2.0-fold of normal limits. Eleven of 25 patients presented with myocardial infarction due to an occlusion of the infarct vessel. In 42 patients without infarction (study group), exercise-induced CI was investigated. RESULTS: A corresponding CI was documented in 32 of 42 patients in a coronary sinus lactate study (reduced lactate extraction 5.6 +/- 4.1%) and in 29 of 40 patients in an ergometry (0.25 +/- 0.06 mV ST depressions). The results differed significantly from a control group of 29 patients without heart disease (p < 0.001). Nitroglycerin (0.8 mg) provoked a further significant deterioration of CI in the 32 of 42 developing a frank cardiac lactate production (-2.6 +/- 6.8%, p < 0.001). The metabolic extent of CI was significantly correlated to the coronary diameters of the proximal and middle segments of left anterior descending artery and the middle segment of left circumflex artery (r = 0.87, p < 0.001). Stigmata of an impaired coronary blood flow such as delayed antegrade filling, segmental backflow phenomenon and local deposition of dye were found significantly more often with increasing coronary diameters (p < 0.04). CONCLUSIONS: "Dilated coronaropathy" is an entity of nonobstructive, ischemic coronary artery disease. Nitroglycerin is of no therapeutic benefit but leads to an aggravation of exercise-induced CI. (+info)
Serial pulsatility index measurements in renal grafts before, during, and after episodes of urinary obstruction.
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The usefulness of pulsatility index determinations for the diagnosis of obstructive collecting system dilatation was investigated in 10 renal transplant patients whose grafts developed urinary obstruction from different causes. For this purpose we compared pulsatility index values obtained (1) before the ultrasonographic detection of obstruction or baseline study, (2) 1 day before surgical repair, and (3) within 2 weeks after surgery. In 7 of 10 obstructed grafts, the pulsatility index values were increased only mildly to moderately preoperatively. In the remaining three grafts, a mild decrease in pulsatility index was observed in spite of severe collecting system dilatation. Changes in pulsatility index were not statistically significant. Impedance measurements appeared not to be useful for diagnosing obstructive collecting system dilatation. (+info)
Transgenic mouse model of stunned myocardium.
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Stunned myocardium is a syndrome of reversible contractile failure that frequently complicates coronary artery disease. Cardiac excitation is uncoupled from contraction at the level of the myofilaments. Selective proteolysis of the thin filament protein troponin I has been correlated with stunned myocardium. Here, transgenic mice expressing the major degradation product of troponin I (TnI1-193) in the heart were found to develop ventricular dilatation, diminished contractility, and reduced myofilament calcium responsiveness, recapitulating the phenotype of stunned myocardium. Proteolysis of troponin I also occurs in ischemic human cardiac muscle. Thus, troponin I proteolysis underlies the pathogenesis of a common acquired form of heart failure. (+info)
Hepatopulmonary syndrome after allogeneic bone marrow transplantation.
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A 10-year-old girl with aplastic anemia received an allogeneic bone marrow transplantation (BMT). Three years after an uneventful course apart from chronic graft-versus-host disease (GVHD) she presented with chronic hypoxemia, reduced diffusion capacity of the lungs, normal spirometric lung function and increased bilirubin and liver enzymes. Intrapulmonary vascular dilatations were demonstrated. Pulmonary complications after BMT may include a hepatopulmonary syndrome (liver disease, hypoxemia, intrapulmonary vascular dilatations). (+info)
Dilatation of the biliary tree in children: sonographic diagnosis and its clinical significance.
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We evaluated sonographically 162 children who met the criteria for biliary tract dilatation in the past 18 years. Of these, 131 patients were diagnosed as having anomalous dilatations of the biliary tree (including 112 with choledochal cysts and 19 with biliary duct dilatation and biliary atresia). Biliary tract dilatations in the other 31 patients were due to secondary causes or normal variants. All cases of intrahepatic biliary tree dilatation and those with both intra- and extrabiliary duct dilatations were anomalous. In 117 cases of extrahepatic biliary tract dilatation only, the mean diameter was widest in cases of choledochal cyst (21.4 +/- 12.1 mm, compared with cases of biliary tract dilatation with biliary atresia (10 +/- 2.4 mm), secondary biliary duct dilatation (8.5 +/- 1.5 mm), and normal variants (4.4 +/- 1.2 mm) (P < 0.001). Of the 43 infants with biliary tree dilatation, 24 (56%) had choledochal cysts and 19 (44%) had biliary tract dilatation associated with biliary atresia. Excluding cases associated with biliary atresia, the accuracy of diagnosing choledochal cysts in extrahepatic biliary tract dilatation was 71% and 97% using cutoffs of 7 mm and 10 mm as the minimum diameter, respectively. (+info)
Sonographic appearance of the ventriculus terminalis cyst in the neonatal spinal cord.
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The ventriculus terminalis or "fifth ventricle" is an ependyma-lined residual lumen of the caudal portion of the spinal cord (the conus medullaris). We present the cases of three neonates with asymptomatic cystic dilatation of the ventriculus terminalis as seen on spinal sonography. Over a 4 year period (1996-1999), we prospectively found three cases in which spinal sonograms demonstrated cystic dilatation of the ventriculus terminalis of the conus medullaris in normal term neonates. Sonograms of the lumbosacral spine of two of the infants demonstrated cystic dilatation of the ventriculus terminalis of the conus medullaris. The third infant had cystic dilatation at the distal tip of the conus medullaris at the origin of the filum terminale. No other abnormalities were noted. The three infants have remained asymptomatic during clinical follow-up periods of up to 3 years. Cystic dilatation of the ventriculus terminalis is an unusual but normal anatomic variant of the conus medullaris that can be visualized on spinal sonograms in neonates. (+info)