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Biomedical subjects

D G Hall

Publications and source records attributed to D G Hall.

118 records · Page 7Linked to original sources
PubMedDate not supplied

Transesophageal echocardiography during repair of congenital cardiac defects: identification of residual problems necessitating reoperation.

One advantage of intraoperative transesophageal echocardiographic (TEE) evaluation during surgery for congenital heart disease is detection of suboptimal repairs, thus providing the opportunity to return to cardiopulmonary bypass (CPB) to repair residual defects. The purpose of this study was to evaluate the impact of TEE on decisions to return to CPB. Two-hundred-thirty infants and children with a variety of defects were studied with size-appropriate TEE probes. Patients were grouped by anatomic defect or surgical procedure for which TEE was requested. After CPB, pre- and post-CPB TEE anatomic, functional, and flow evaluations were compared. TEE findings prompted a return to CPB to repair residual defects in 17 of 230 (7.4%) patients. By diagnosis, return to CPB occurred in 9 of 28 (32%) patients with left ventricular outflow tract obstruction, 5 of 78 (6.4%) patients with ventricular septal defect, 1 of 16 (6%) patients with switch-repaired transposition, 1 of 32 (3%) with aortic valve disease, and 1 of 3 with double outlet right ventricle. All post-CPB diagnoses were confirmed during reoperation. Although post-CPB TEE provided reassuring information in patients with other diagnoses, TEE impact on return to CPB appears to be significant in a small group of primary diagnoses. The sensitivity and specificity of TEE determination of the need for reoperation were 89% and 100%, respectively. By identifying the site, severity, and mechanism of residual problems, TEE offers substantial utility in detection of residual problems in need of reoperation.

Adolescent↗
PubMedDate not supplied

Left ventricular outflow tract obstruction: an indication for intraoperative transesophageal echocardiography.

Transesophageal echocardiography (TEE) provides detailed anatomic imaging of both discrete and complex forms of left ventricular outflow tract (LVOT) obstruction, and Doppler techniques provide additional information regarding the site, mechanism, and severity of the obstruction. Because the transaortic surgical approach to LVOT obstruction often provides limited direct visualization during surgery, we sought to evaluate the utility of intraoperative TEE during surgery for LVOT obstruction. We tested the hypotheses that intraoperative TEE would (1) be useful in defining the level and nature of LVOT obstruction, (2) serve to direct the surgical approach, (3) define the adequacy of relief of LVOT obstruction, and (4) detect surgical complications. Study population consisted of a consecutive series of 27 infants and children undergoing surgery for LVOT obstruction. Patient age ranged from 0.5 to 17.9 years, and weight from 5.4 to 71.2 kg. In 14 patients LVOT obstruction resulted from a discrete membrane, whereas 13 had complex forms of LVOT obstruction. Fully anesthetized and monitored patients were examined with 5 MHz TEE probes appropriate to the size of the patient. In the 14 patients with discrete LVOT obstruction, discrete membranes were identified by TEE in all; gradients ranged from 36 to 75 mm Hg. In 13 of 14 patients, postbypass TEE demonstrated removal of the membrane and excellent relief of gradients. In one of these patients, TEE demonstrated a small ventricular septal defect acquired during resection; the patient was returned to bypass for closure. In one patient, return to bypass for further resection of LVOT obstruction was prompted by TEE demonstration of a high residual gradient. In the 13 patients with complex LVOT obstruction, TEE demonstrated the complexity of LVOT obstruction in all. Gradients ranged from 4 to 95 mm Hg. Although this information was used in surgical planning, five patients had high residual gradients after bypass and underwent further resection. An additional two were returned to bypass for mitral valve replacement. Overall, 8 of 27 patients (29.6%) were returned to bypass based on TEE demonstration of residual anatomic or hemodynamic abnormalities. This occurred significantly more frequently in complex LVOT obstruction than in discrete LVOT obstruction (p = 0.045). We conclude that intraoperative TEE has substantial utility in the demonstration of site, mechanism, and severity of LVOT obstruction and for surgery designed to relieve LVOT obstruction. We believe that TEE should be an integral part of surgical management of LVOT obstruction.

Adolescent↗
PubMedDate not supplied

Lexical form class information guides word-to-object mapping in preschoolers.

We demonstrate that lexical form class information can play a powerful role in directing the establishment of word-to-object mappings in referentially ambiguous situations. A total of 144 3- and 4-year-olds heard a novel label, modeled syntactically as either a proper name or an adjective, for a stuffed animal of a familiar kind. We then added a second object of the same kind and asked children (1) to choose one of the two objects as the referent of a second novel label, also presented syntactically as either a proper name or an adjective, and (2) to decide whether this second label could also apply to the object they did not choose. In each of three experiments, preschoolers were most likely to reject two words for the same object if both words were proper names (as if one dog could not be both "Fido" and "Rover"). They were significantly less likely to do so if both were adjectives (as if one dog could be both "spotted" and "furry") or if one was a proper name and the other was an adjective (as if one dog could be both "Fido" and "furry"). Information about lexical form class thus contributed significantly to the formation of linkages between words and objects.

Child, Preschool↗
PubMedDate not supplied

Echocardiographic detection of flail left atrioventricular valve cusp from ruptured chordae tendineae in 4 dogs.

Echocardiography was used to identify a flail left atrioventricular valve cusp caused by ruptured chordae tendineae in each of 4 dogs; two-dimensional echocardiography was superior to M-mode echocardiography in identifying the flail cusps. The following findings on two-dimensional imaging were characteristic: the tip of the flail cusp extended beyond the line of left atrioventricular valve cusp closure and pointed toward the left atrium in systole; the tip was thrust into the left ventricle, and then toward the left ventricular outflow tract in diastole, forming a convex surface to the cusp, which faced toward the left ventricle. The flail motion of the left atrioventricular valve cusp was best observed in the right parasternal long axis or left apical four-chamber views, in a plane parallel to the long axis of the left ventricle and left atrium. Rupture of chordae tendineae leading to flail cusp was attributed to chronic valve degeneration (endocardiosis) in all 4 dogs. Echocardiographic or clinical diagnoses were confirmed by postmortem gross and microscopic studies in all dogs.

Animals↗
PubMedDate not supplied

Experience of transferring an integrated hospital-administration system from a CODASYL data-base to a standard MUMPS file structure.

University College Hospital, a teaching hospital situated in Central London, has been using computers since 1964. Development of an integrated on-line hospital administration computer system was started in 1974. By mid 1977, the components of the system which had been implemented included a patient Master Index, Registration of new patients, Waiting Lists, Bed State, Out-patient Appointments, X-ray, Microbiology and Disease Index. The system was implemented using the Rank Xerox Data Systems (CODASYL based data-base management software, with the majority of applications running on a terminal network supported by transaction processing programs. The experience gained during three years of using such a system is reviewed, with particular emphasis on the ways in which the system matched up in practice to the expected benefits of data-base management facilities. In early 1977, it was decided to replace the Rank Xerox mainframe with a minicomputer which was considered to be a more cost-effective solution to the hospital's computing requirements. The machine selected a PDP 11-70, is running the Digital Equipment Corporation's implementation of Standard MUMPS, an interpretive language developed in a hospital environment, with its own file management software. The decisions which were made in redesigning the existing computer systems for the new machine are discussed. The progress made to date in the transfer of applications from the mainframe to the mini is reviewed, and some of the features of the software available on each machine and its suitability for the implementation of on-line data management and retrieval systems are compared.

Computers↗
PubMedDate not supplied

Long-range observations with external aortic grafts.

The late results of aortic aneurysms treated by external grafting are presented. This procedure consists of completely dissecting the involved aortic segment and suturing it in a well-fitted tubular Dacron prosthesis. The operation was carried out under the following circumstances: (a) Small fusiform aneurysm of the abdominal aorta. (b) Small and medium-sized aneurysms of the thoracic aorta. (c) Aneurysms unfavorably located in the very old and very debilitated. (d) Aneurysms involving the origin of the renal arteries. (e) Aneurysmatic dilatation of the aortic arch. Sixty-two patients were operated upon with this method with the follow-up period ranging from three months to seven years. There were no deaths during this period which could be directly related to either the aneurysm or the procedure itself.

Aorta, Abdominal↗