Strut failure of the Starr-Edwards cloth-covered metallic ball prosthesis. Report of two asymptomatic cases and review of the overall experience.

Two cases of asymptomatic strut failure of an aortic Starr-Edwards cloth-covered metallic ball prosthesis are reported. Strut failure can be asymptomatic for years. Available information on the overall worldwide experience of six cases is reviewed and suggestions made for early diagnosis and treatment of this rare complication.

Massively Parallel Computers: The Connection Machine and NON-VON.

The demand for high-speed computers is increasing, and as the limits on single-processor computers are approached, researchers are turning their attention to parallel computers. Parallel computers have more than one processing element; massively parallel computers contain many processing elements. Constructing computers on this scale and learning how to program them effectively will be major challenges in the next decade. Several such computers, for example the Connection Machine and the NON-VON, are under development.

Computer-assisted diagnosis of orthopedic gait disorders.

A computer program was developed to help diagnose orthopedic gait disorders. Designing and implementing the program, as well as the program's method of operation are described. The main features of the program include: a knowledge base of facts about orthopedic gait, organized into premise-conclusion pairs; a goal-directed reasoning chain that causally relates the facts; and a symbolic structure that allows limited English discourse between the user and the computer. Results of the project indicate that the complex area of gait analysis does lend itself to diagnosis by computer and that this prototype has potential as an aid to physical therapists in the classroom and in the clinic.

Reduction of blood usage in open heart surgery.

A series of 142 adult patients undergoing open-heart surgery were studied. All known blood-conservativing methods were utilized in an attempt to use as little blood as possible. Hemodilution, autologous transfusion, prevention of wasting of blood, and management of postoperative anemia were the measures employed. An average of 2.66 units of blood were given per patient during the entire hospital stay. Twenty patients were not given any blood at all. The patients were removed from cardiopulmonary bypass without difficulty when the hematocrit reading was in the high teens or low twenties. Later in the postoperative period the patients seemed to progress without difficulty with hematocrit readings of 22 to 25 percent.

Factors predictive of perioperative myocardial infarction during coronary operations.

The diagnosis of perioperative myocardial infarction (PMI) in our patients was based upon electrocardiography, vectorcardiography, and postoperative enzyme changes. A group of 303 patients operated on between January and September, 1972, formed the basis of this study. Three groups were identified from among these patients. Group A was composed of 90 consecutive patients in whom MI was excluded by all criteria. Group B comprised 25 patients with proved MI and yielded the 8% incidence of MI among our patients. Group C included 34 patients with triple-vessel disease who did not sustain MI. Significantly more patients sustaining MI had preinfarction angina and severe coronary artery disease. The incidence of MI was also higher in patients with diffuse disease and those in whom the lesions could not be totally bypassed. A statistical correlation with longer pump runs and periods of anoxia was obtained. There was some suggestion that the preoperative location of the hypokinetic segment determined the site of MI in patients.