We report a study showing that two-dimensional echocardiography is capable of visualizing a ventricular septal defect as small as 3 mm. The physical parameters which determine the visibility of an aperture in the myocardium include the presence of anterior refractile tissue, the amount of ultrasound beam focusing and range over which this occurs, the angle of incidence of the ultrasound beam on the septum, and the number of lines of information per degree of sector sweep. These factors are illustrated by in vitro tests. The influence of operator controllable variables in two-dimensional sector scanning echocardiography is discussed.

Child, Preschool↗

PubMedDate not supplied

Pulse-Doppler ultrasound and its clinical application.

Doppler devices can provide clinically useful information about blood flow. This paper describes how a pulse-Doppler instrument has been linked to a B-scan machine so that flow patterns in any ultrasonically accessible vessel can be monitored from the skin surface. The same transducer is used for both modes of investigation to enable accurate and reliable positioning of the sample-volume. After briefly summarizing the principles of continuous-wave and pulse-Doppler operation, the concepts and relative advantages of coherent and non-coherent detection are explained. The potential clinical uses of the pulse-echo-Doppler hybrid and Doppler devices in general are then discussed.

Blood Flow Velocity↗

PubMedDate not supplied

Assessing with care.

Explore the source record for details and available documents.

Adolescent↗

PubMedDate not supplied

Failure of patients to attend a medical outpatient clinic.

Failure of patients to attend outpatient clinics is common and costly. In one consultant's general medical and gastrointestinal outpatient clinic, 38% of new patients failed to keep at least one appointment, 17% did not attend for their first outpatient consultation and, of these, 59% failed to keep a second appointment sent to them. Of the patients who did attend for their first consultation 12% did not keep their next two appointments. Failure to attend was more common in men, young patients, patients from certain inner city areas, patients on the lists of certain general practices, and those who had already defaulted once. Possible background reasons for default are discussed, suggestions for further study proposed, and an attempt made to look for ways to reduce the extent of the problem.

Adolescent↗