Search PubMed⌕ Search

Biomedical subjects

N Herrera

Publications and source records attributed to N Herrera.

At least 37 records · Page 2Linked to original sources
PubMed1986

Percutaneous transluminal balloon dilatation for discrete subaortic stenosis.

Seven patients, mean age 8 +/- 3.6 years, with clinical and hemodynamic diagnoses of discrete subaortic stenosis were treated by percutaneous transluminal balloon dilatation (PTBD) of the membrane during cardiac catheterization. One patient had an associated aortic coarctation that was first dilated. After PTBD left ventricular (LV) systolic pressure decreased significantly, from 181 +/- 25 to 139 +/- 11 mm Hg (p less than 0.005); peak gradient diminished from 65 +/- 18 to 12 +/- 9 mm Hg (p less than 0.001). Mild aortic regurgitation was present in 6 patients during basal conditions. After PTBD, the same degree of regurgitation was observed in all but 1 patient, in whom it disappeared. There were no major complications. Clinical observations after PTBD were consistent with hemodynamic findings. Precordial thrill always disappeared and the peak murmur became earlier in systole. In 2 patients the discrete subaortic stenosis was clearly visualized at 2-dimensional echocardiography as a fixed subvalvular structure throughout the cardiac cycle. After dilatation this was only identifiable at its implantation base; during contraction there was no fixed structure at the LV outflow tract. Four patients were hemodynamically reevaluated 6.7 +/- 1.7 months later and were found to have LV pressure relief and a degree of aortic regurgitation similar to those observed immediately after PTBD.

Angioplasty, Balloon↗
PubMed1985

Percutaneous transluminal angioplasty of stenotic ductus arteriosus.

This article describes our in vitro experience of balloon angioplasty of the ductus arteriosus (DA) in three post mortem human specimens, as well as an in vivo dilatation of a stenotic DA. The in vitro histologic observations revealed disruption of the intima and areas of pathologically fragmented and disorganized fibers at the media, with integrity of the ductal wall in all three DA. These findings led us to attempt percutaneous transluminal angioplasty (PTA) of a stenotic DA in a 2.3-kg newborn infant with hypoplastic left heart syndrome in a very deteriorated clinical condition. A Rashkind septostomy was associated with PTA of the stenotic DA. Following this, the gradients across the DA and across the atrial septum disappeared and the ductal angiographic diameter increased. Although an improved clinical condition was observed during the following hours, he died 1 day after. At necropsy, we found integrity of the ductal wall with histological changes similar to that observed in vitro. We conclude that PTA of stenotic DA could represent an alternative for palliative treatment of DA-dependent congenital heart disease.

Angioplasty, Balloon↗
PubMed1985

World health organisation inter-laboratory comparison study in 12 countries on quality performance of nuclear medicine imaging devices.

Twelve countries participated in the WHO intercomparison for which transmission CAP (College of American Pathologists) brain and CAP liver phantoms and emission London liver phantoms were used. A total of 157 imaging devices were tested. Overall results from the phantoms revealed a wide range of targets detected. For the CAP-phantoms target detectability dropped below 50% for target sizes less than 9 mm and below 60% for target contrast less than 0.84:1. On average one false positive and six false negative results were reported using CAP-brain phantoms and one false positive and one false negative result using CAP-liver phantoms. For the London liver phantoms containing the tissue equivalent rubber abdominal simulation the target of 1 cm was never visualised. Two targets in this phantom (2 cm and 2.5 cm) were correctly identified in 34% of studies and one of these targets in 52% of studies. Equivocal and false positive results were reported in 42%. The WHO inter-comparison demonstrated the need to establish new, or to improve the existing, quality control programmes.

Brain↗
PubMed1984

Detection of gastrointestinal bleeding by radionuclide scintigraphy.

Scanning with Technetium 99m labeled autologous red blood cells was performed in 59 patients with clinical suspicion of acute and/or intermittent, chronic gastrointestinal bleeding. In 36 patients (61%), a definite site of bleeding could be demonstrated. A strong correlation with other modalities such as upper and lower gastrointestinal endoscopy, contrast angiography, and surgical exploration was found. Overall sensitivity of the procedure was 91%; specificity 100% and accuracy 93.3%. It is suggested that radionuclide scintigraphy provides a completely noninvasive, simple, and sensitive procedure which may be routinely used for the detection and localization of gastrointestinal bleeding.

Adult↗
PubMed1982

Comparison of interlaboratory survey date in terms of receiver operating characteristic (ROC) indices.

Receiver Operating Characteristic (ROC) analysis in the field of visual imaging has hitherto dealt with the performance of imaging modalities, system displays, or individual readers. This study combines previously established interlaboratory survey techniques with ROC concepts to evaluate selected indices of group discrimination and of group decision criteria in a quantitative and comparative manner. One hundred forty-two subscribers to the College of American Pathologists Phantom-Imaging Series performed a series of visual detection tasks on a fabricated radioactive phantom image. Results suggest that group performance may be legitimately assessed by ROC analysis if the variables of system modality, image display, and cases are controlled, and the number of trials is sufficiently large. The latter condition may be fully satisfied through interlaboratory survey techniques that utilize currently existing peer groups.

Models, Structural↗
PubMed1982

Scintigraphic detection of segmental bile-duct obstruction.

In a patient with acute obstructive jaundice, cholescintigraphy with technetium-99m-labeled iminodiacetic acid (HIDA) showed uniformly reduced uptake in the left lobe of the liver. Endoscopic retrograde cholangiopancreatography (ERCP) demonstrated cholelithiasis and obstruction of the distal hepatic duct. Surgery, and later a T-tube cholangiogram, confirmed the presence of numerous stones in the left intrahepatic and common hepatic ducts. The liver was free of tumor. Intrahepatic segmental ductal obstruction may produce a spectrum of patterns on hepatobiliary imaging ranging from reduced uptake to intrahepatic pooling.

Aged↗