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Biomedical subjects

F O'Connor

Publications and source records attributed to F O'Connor.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cardiovascular responses to lower body negative pressure in trained and untrained older men.

To determine whether aerobic conditioning alters the orthostatic responses of older subjects, cardiovascular performance was monitored during graded lower body negative pressure in nine highly trained male senior athletes (A) aged 59-73 yr [maximum O2 uptake (VO2 max) = 52.4 +/- 1.7 ml.kg-1 x min-1] and nine age-matched control subjects (C) (VO2 max = 31.0 +/- 2.9 ml.kg-1 x min-1). Cardiac volumes were determined from gated blood pool scintigrams by use of 99mTc-labeled erythrocytes. During lower body negative pressure (0 to -50 mmHg), left ventricular end-diastolic and end-systolic volume indexes and stroke volume index decreased in both groups while heart rate increased. The decreases in cardiac volumes and mean arterial pressure and the increase in heart rate between 0 and -50 mmHg were significantly less in A than in C. For example, end-diastolic volume index decreased by 32 +/- 4 ml in C vs. 14 +/- 2 ml in A (P < 0.01), mean arterial pressure declined 7 +/- 5 mmHg in C and increased by 5 +/- 3 mmHg in A (P < 0.05), and heart rate increased 13 +/- 3 beats/min in C and 7 +/- 1 beats/min in A (P < 0.05). These data suggest that increased VO2 max among older men is associated with improved orthostatic responses.

Aged↗
PubMed1991

Boxing: the preparticipation evaluation.

Boxing is a controversial sport that has drawn public and physician criticism since its inception in 900 BC. The American Medical Association has recently taken a formal position to ban boxing because of the alleged dangers, including the possibility of the long-term effect of dementia pugilistica. Proponents of amateur boxing are working diligently to document this claim both as premature and false. They cite amateur boxing's purpose as one boxer's attempt to outpoint or outscore his opponent by utilization of superior strength and skill. Despite this medical and political controversy, thousands of primary care patients are boxing. This report offers the physician guidelines for the preparticipation evaluation. Specific disqualifying conditions are addressed.

Boxing↗
PubMed1989

[Role of intraoperative echo-Doppler color echocardiography in cardiac surgery. Preliminary study].

Intraoperative echocardiography with Doppler color flow imaging technique can provide the surgeon with an immediate and direct assessment of cardiac anatomy and function. To determine the utility of this recent technique, we have examined 15 patients pre, per, and postoperatively with Doppler color flow imaging. The intraoperative study was performed before and after cardiopulmonary bypass. A sterile transducer was placed directly on the epicardial surface of the heart, and multiple views were recorded. Intraoperative echocardiography with Doppler color flow imaging technique demonstrated excellent correlation with preoperative and postoperative findings, allowing an immediate evaluation of the surgical results. These preliminary results suggest that intraoperative Doppler color flow imaging technique is a valuable adjunct in heart surgery. It is particularly useful in valve repair, and in surgical repair of congenital heart disease.

Cardiac Surgical Procedures↗
PubMed1983

Comparative electrophysiological evaluation of atrial activation and sinoatrial node function following Senning and Mustard procedures: an experimental study.

We compared several electrophysiological variables before and after Mustard and Senning procedures in 14 mongrel dogs and made the following three observations. First, after the Senning operation, the atrial activation in the areas of the anterior and middle internodal tracts is undamaged. After the Mustard procedure, however, conduction through the interatrial septum is practically abolished. Both techniques damage the area of the posterior internodal tract. On the whole, there is greater dispersion of atrial epicardial mapping with the Senning operation. Second, several degrees of depression in the sinus node automatism and intraatrial conduction were observed with both techniques. Third, atrioventricular block in various degrees was observed only after the Mustard procedure. The atrioventricular dissociation observed after the Senning operation was dependent on sinus pacemaker dysfunction only. We think that from the electrophysiological point of view, the Senning procedure is a valid alternative for repair of transposition of the great arteries.

Animals↗
PubMed1980

Late embolization of disc occluder of a Beall mitral prosthesis with survival.

A case of arterial embolization of a Beall mitral prosthesis disc (model 104) 5 1/2 years after implantation is presented. The patient was referred to use 3 days after the onset of acute symptoms and was immediately operated upon in pulmonary edema and cardiogenic shock. The migrated disc was removed from the abdominal aorta 26 days later, showing marked signs of wear. The postoperative course was complicated and the patient made a slow recovery. It is suggested that patients with models 103 and 104 Beall mitral prostheses be followed very closely and that electric valve substitution should be considered when first signs of prosthetic attrition are noted.

Adult↗
PubMed1976

Cardiac echinococcosis: report of 3 cases and review of the literature.

Three patients who underwent successful surgical treatment of cardiac hydatid disease are discussed. The nonspecificity of diagnostic measures and the importance of keeping this diagnosis in mind when faced with a patient coming from an area where hydatidosis is endemic are stressed. We propose the use of cardiopulmonary bypass in the surgical treatment of this problem.

Adolescent↗
PubMed1975

Rate factors in development of the high-pressure neurological syndrome.

The effect of varying the pressure/time profile upon development of tremors and convulsions of the high-pressure neurological syndrome was studied in adult mice and squirrel monkeys and in baby mice. Two distinct response patterns were observed. In the adults rapid compression produces early onset of convulsions; convulsions subside rapidly when animals are held at constant pressure just above the convulsion point; and interrupted compression schedules show that total compression time rather than instantaneous compression rate at the moment seizures develop is the controlling parameter. Baby mice up to 12 days of age, by contrast, fail to show any perceptible relation between compression rate and convulsion threshold pressure (Pc); their seizures continue for a considerable period of time after a constant pressure level just above the convulsion threshold has been reached; and interrupted compressions of type a fail to change their convulsion threshold. Together with supplementary data regarding tremor thresholds and the transient increase of convulsion thresholds by prior seizures these results lead to a proposed schema describing these phenomena in terms of a pressure-dependent primary event predisposing to tremors and convulsions; a time-dependent event counteracting the convulsions (absent in baby mice); and a transient effect of prior convulsions, raising subsequent Pc.

Age Factors↗