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Biomedical subjects

B A Ross

Publications and source records attributed to B A Ross.

At least 19 recordsLinked to original sources
PubMed1997

Unenhanced helical CT for suspected acute appendicitis.

OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of unenhanced helical CT scans in patients with a suspected acute appendicitis. SUBJECTS AND METHODS: Over a 20-month period, 109 adult patients with suspected acute appendicitis were referred by the emergency department for an unenhanced helical CT scan. Each scan was obtained in a single breath-hold from the T12 vertebral body to the public symphysis using a 5-mm collimation and a pitch of 1.6. No patients were given oral or IV contrast media. The primary CT criteria for diagnosing acute appendicitis was the identification of an appendix with a transverse diameter larger than 6 mm with associated periappendiceal inflammatory changes. The presence of an appendicolith was considered a secondary finding as was isolated periappendiceal inflammation; however, appendicitis was not diagnosed in such patients unless an enlarged appendix was definitely identified. Final diagnoses were established by surgical or clinical follow-up and were compared with the original CT reports. RESULTS: We found 66 true-negatives, 37 true-positives, four false-negatives, and two false-positives that yielded a sensitivity of 90%, a specificity of 97%, a positive predictive value of 95%, a negative predictive value of 95%, and an accuracy of 94%. An alternative diagnosis was established by an unenhanced helical CT scan in 24 patients (22%), which included cecal diverticulitis (seven patients), urinary tract disease (five patients), adnexal pathology (four patients), sigmoid diverticulitis (two patients), small bowel disease (three patients), right lower quadrant tumor (two patients), and an infected dialysis catheter (one patient). CONCLUSION: Unenhanced thin-section helical CT is an accurate, effective technique for diagnosing acute appendicitis.

Acute Disease↗
PubMed1996

Inadvertent atrioventricular block during radiofrequency catheter ablation. Results of the Pediatric Radiofrequency Ablation Registry. Pediatric Electrophysiology Society.

BACKGROUND: Inadvertent atrioventricular block is a complication of radiofrequency ablation. The present study is an analysis of the incidence, significance, and factors associated with inadvertent atrioventricular block during radiofrequency catheter ablation in childhood and adolescence. METHODS AND RESULTS: The records of the Pediatric Radiofrequency Ablation Registry were reviewed. Between January 1, 1991, and April 1, 1994, atrioventricular block occurred in 23 of 1964 radiofrequency ablations (1.2%): 14 as third-degree block (3 transient) and 9 as second-degree block (5 transient). Atrioventricular block occurred from 5 seconds to 2 months (mean, 4.1 days; median, 15 seconds) after the onset of the energy application. Eight transient cases lasted 1 hour to 1 month (mean, 9.4 days; median, 7 days). Inadvertent atrioventricular block was related to the ablation anatomic site: 3 of 111 (2.7%) anteroseptal, 11 of 106 (10.4%) midseptal, and 2 of 197 (1.0%) right posteroseptal sites (P = .0007) for anteroseptal, P = .0001 for midseptal, and P = .17 for right posteroseptal versus nonright septal sites). Five of 314 (1.6%) ablations for atrioventricular nodal reentrant tachycardia resulted in atrioventricular block (P = .004 versus nonright septal sites). Compared with a matched subgroup, radiofrequency ablation experience was the only significant risk factor (32.7 versus 106.6, P = .002) for the occurrence of atrioventricular block. CONCLUSIONS: Inadvertent atrioventricular block may occur during or late after radiofrequency catheter ablation. It is associated with ablations for (1) anterior and midseptal accessory pathways and atrioventricular nodal reentry and (2) relative institutional inexperience.

Adolescent↗
PubMed1996

Mapping and radiofrequency ablation of intraatrial reentrant tachycardia after the Senning or Mustard procedure for transposition ofthe great arteries.

The Senning and Mustard procedures are often associated with the development of atrial tachyarrhythmias, which may be a cause of sudden death. We hypothesized that atrial surgery creates barriers to impulse propagation, establishing potential routes for atrial reentry, and that mapping combined with knowledge of the surgical anatomy could identify zones that are critical to the tachycardia to be targeted for radiofrequency catheter ablation. Patients underwent mapping to identify early sites of atrial activation that were related to anatomic or surgically created obstacles, with confirmation by pacing to demonstrate concealed entrainment. Radiofrequency lesions were placed to connect these obstacles, while observing for tachycardia termination. Thirteen tachycardias were attempted in 10 patients, 10 successfully. Three patients had 2 distinct tachycardias. Successful sites were in right atrial tissue, although in many, a retrograde approach to the pulmonary venous atrium was necessary. Ablation of the clinically documented tachycardia was successful in 9 of 10 patients. The most common successful site was the region of the coronary sinus mouth, approached antegrade or retrograde. Ablation of intraatrial reentrant tachycardias after the Senning or Mustard procedure is feasible using concealed entrainment mapping techniques, but requires a detailed knowledge of the individual surgical anatomy and the ability to approach the pulmonary venous atrium. Radiofrequency ablation offers significant advantages over other management modalities in this patient group.

Adolescent↗
PubMed1996

Normal variations in the lateral contour of the head and neck of the pancreas mimicking neoplasm: evaluation with dual-phase helical CT.

OBJECTIVE: The purpose of this study was to analyze variations in the lateral contour of the head and neck of the pancreas that can mimic pancreatic masses on CT imaging. MATERIALS AND METHODS: We retrospectively reviewed dual-phase helical CT examinations of 119 patients who had no clinical or CT evidence of pancreatic disease. Contour variations of the head and neck of the pancreas were analyzed and were classified according to their anatomic orientation. RESULTS: Forty-one (34.5%) of the 119 patients had discrete lobulations of pancreatic tissue greater than 1 cm lateral to the gastroduodenal or anterior superior pancreaticoduodenal artery. These lobulations showed normal pancreatic density on both predominantly arterial and portal venous phase images. Contour variants of the pancreatic head and neck were categorized as three main types: anterior (type I), posterior (type II), and horizontal (type III). In the 119 patients, we found 12 type I variants (10%), 23 type II variants (19%), and six type III variants (5%). CONCLUSION: Variations in the lateral contour of the normal head and neck of the pancreas are common. Recognition of the different types of contours may help avoid misinterpretation of normal variants as pancreatic masses.

Adolescent↗
PubMed1994

A comparison of omeprazole and ranitidine in the prevention of recurrence of benign esophageal stricture. Restore Investigator Group.

BACKGROUND/AIMS: Dilatation combined with subsequent pharmacological control of gastroesophageal reflux represents a logical but poorly documented approach to the management of benign esophageal stricture. This large trial (366 patients) aimed to assess whether omeprazole as the most effective available medication for gastroesophageal reflux disease prevents recurrent stricture formation. METHODS: Patients (n = 366) were randomized in a double-blind study to undergo either omeprazole (20 mg once daily; 180 evaluable patients) or ranitidine therapy (150 mg twice daily; 185 evaluable patients) for 1 year after dilatation to 12-18-mm diameter (36-54F gauge). Subsequently, endoscopy and dilatation were performed when clinically indicated and endoscopy on completion. Symptoms were assessed at clinic visits every 3 months and using weekly diary cards. RESULTS: Fewer patients undergoing omeprazole therapy required redilatation compared with those on ranitidine (43 of 143 [30%] vs. 66 of 143 [46%] by 12 months; P < 0.01), and patients in the omeprazole group needed fewer redilatations during the year (0.48 vs. 1.08; P < 0.01). On completion, symptom relief favored omeprazole: 76% of patients in the omeprazole group were free of dysphagia (compared with 64% in the ranitidine group; P < 0.05); 83% were able to accept a normal diet (69%; P < 0.01); and 65% were completely asymptomatic (43%; P < 0.001). CONCLUSIONS: Omeprazole, 20 mg once daily, was more effective than ranitidine, 150 mg twice daily, as prophylaxis against stricture recurrence and in providing symptom relief.

Adult↗
PubMed1994

Differences in leucocyte-endothelium interactions between normal and adenocarcinoma bearing tissues in response to radiation.

Previously, we demonstrated that the interaction between leucocytes and endothelial cells in tumour tissues is greatly diminished compared with normal tissues under several induced inflammatory conditions. Radiation has been reported to cause release of inflammatory mediators and to promote neutrophil adhesions to cultured endothelial monolayers. In this study, we tested the hypothesis that radiation would cause increased leucocyte rolling and adhesion in both tumour and normal tissues. We examined these two parameters in response to 6 Gy of gamma-radiation in mammary adenocarcinomas implanted into rat skinfold window chambers as well as normal (i.e. non-tumour-bearing) preparations. Leucocyte rolling and adhesion were measured in terms of flux of rolling leucocytes (F(rolling)) and density of adhering leucocytes (D(adhering)) in microvessels. F(rolling) and D(adhering) were measured in two groups of preparations: irradiated and control. In normal preparations, F(rolling) and D(adhering) were both increased significantly by radiation. In contrast, in adenocarcinoma-bearing preparations, F(rolling) and D(adhering) were either unchanged (in the tumour centre) or reduced (in tumour periphery and the normal tissue surrounding the tumour) by radiation. Radiation did not cause changes in haemodynamics in these preparations, thus the observed changes in leucocyte rolling and adhesion could not be accounted for by haemodynamic factors. These results indicate that: (1) in normal preparations, radiation could cause inflammation as manifested by increased leucocyte rolling and adhesion; and (2) in tumour-bearing preparations, radiation caused changes in the vascular surface properties such that they became less adhesive to leucocytes. Such differences in radiation response may have important implications for radiation therapy and provide new insights into the unique features of tumours.

Adenocarcinoma↗
PubMed1992

Collaboration in task analysis for developing a database to record the essential clinical behaviors of nursing students.

This database for recording the Essential Clinical Behaviors of nursing students is the result of collaboration between nursing faculty and an instructional designer at Ball State University in Muncie, Indiana. The database was developed to aid nursing instructors in recording and tracking those student behaviors and skills essential to nursing education. The developers of the database are continuing to work toward the goal of having students record data and prepare reports. This would enable the students to be more self-directed in seeking appropriate and essential clinical experiences.

Computer-Assisted Instruction↗
PubMed1991

Abnormal responses to orthostatic testing in children and adolescents with recurrent unexplained syncope.

Syncope in the pediatric age group is a frequent event. Most often the cause is readily apparent--i.e., orthostatic hypotension or a vasovagal event. However, there are a large number of children with frequent recurrent unexplained syncope. Neither history, physical examination, nor standard testing reveals a cause. One hundred four consecutive patients were evaluated by orthostatic testing after standard methods found no cause for the recurrent syncope. Forty-seven (44%) of these 104 patients had syncope produced by orthostatic testing. Twenty-six of the 47 (55%) became syncopal within 5 minutes of testing initiation and 21 of the 47 (45%) after 5 to 11 minutes of testing. These patients had an average decrease of 81.5 mm Hg in blood pressure and a 25 beat/min decrease in heart rate. Of 12 control subjects, none lost consciousness with standing times as long as 14 minutes. Pacing was ineffective in preventing syncope, as two patients with a previously implanted normally functioning pacemaker had recurrent syncope clinically. Syncope was also induced by orthostatic testing, with the pacemaker showing a normal response with pacing as the patient became bradycardic. The syncopal event produced by orthostatic testing occurred with a downward blood pressure trend and a narrowing of the pulse pressure without a significant increase in heart rate. This was followed by a sudden drop in blood pressure and then by bradycardia. There is a group of children and adolescents with recurrent unexplained syncope due to abnormal orthostatic control mechanisms. Orthostatic testing appears helpful in identifying these patients.

Adolescent↗
PubMed1991

The effect of exercise on the atrial electrogram voltage in young patients.

Atrial electrogram sensing is an important function in active individuals with permanently implanted bipolar dual chamber pacing systems. We undertook to determine the effect of vigorous exercise on the atrial electrogram size in 11 children and young adults (average age 12 years). Using a telemetry signal through a handheld programming wand, nine tracings were completely and clearly recorded for analysis. Six patients had tined/passive fixation atrial leads and three patients had screw-in/active fixation lead systems. All leads were bipolar. The atrial electrogram size for each patient was measured at rest and at each minute of exercise. The atrial electrogram size decreased with exercise from a mean of 5.08 mV to 3.44 mV (range 0.9-4.25 mV) (P = 0.002). The 1.64 mV mean decrease represented a 33.8% reduction (range 19%-56%) (P less than 0.001). There was no difference in the change in atrial electrogram size between the two lead types. Treadmill exercise testing with telemetric data of atrial electrograms showed a decrease in atrial electrogram size produced by exercise and may be helpful in determining appropriate atrial sensitivity settings in selected individuals. Because of the documented decrease in atrial electrogram size produced by exercise, we recommend obtaining maximal atrial electrograms at the time of implant and use of pacing systems that allow maximal flexibility in atrial sensing especially in athletically active individuals.

Adolescent↗
PubMed1991

Cellular electrophysiology of neonatal and adult rabbit atrioventricular node.

Adult and neonatal rabbit atrioventricular node (AVN) preparations were studied using transmembrane and surface electrogram recordings. Action potentials were categorized into four types, atrionodal (AN), nodal (N), "high" nodo-His (NH) (HNH), and "low" NH (LNH), according to their action potential characteristics and their location within the A-H interval. The electrophysiological parameters of the lower three regions were identical between the two age groups. Action potentials from the neonatal AN region were lower in amplitude and maximum diastolic potential than they were in the adult. The N cell action potential parameters did not differ between the two age groups, however, there did appear to be qualitative differences. AVN conduction times (A-H intervals) were the same in both age groups, as were the antegrade and retrograde refractory periods, and the Wenckebach intervals. Pacemaker activity was significantly greater in the neonates than in the adults and, in 11 of 13 neonatal preparations, originated in the AN region or higher. In 13 of 14 adult preparations, pacemaker activity resided within the AVN.

Action Potentials↗
PubMed1990

Congenital complete atrioventricular block.

The various etiologies, pathologic findings, clinical concerns, and features of congenital complete atrioventricular block are presented and discussed. In addition, prenatal and antenatal diagnostic techniques are explained and analyzed. Lastly, treatment and the issues involved in deciding proper treatment are discussed in such a way that the general pediatrician can help the family to understand and handle the problem.

Autoimmune Diseases↗