PubMed Health⌕ Search

Biomedical subjects

J M Griffith

Publications and source records attributed to J M Griffith.

46 records · Page 3Linked to original sources
PubMed1975

Measurement of mitral orifice area in patients with mitral valve disease by real-time, two-dimensional echocardiography.

A quantitative assessment of mitral valve orifice area can be achieved in patients with pure mitral stenosis by cardiac catheterization. In the presence of mitral regurgitation, however, accurate measurement often is impossible because total diastolic flow through the mitral valve frequently is unknow. Using a recently developed real-time, two-dimensional echocardiography system, we are able to obtain cross-sectional images of the mitral valve by scanning the heart perpendicular to its long axis at the level of the tip of the mitral leaflets. Twenty consecutive patients undergoing operation for mitral valve disease were studied during the week prior to operation. In 18 of 20 (90%) the mitral orifice was imaged successfully in early diastole by two-dimensional echocardiography so that mitral valve orifice area could be measured directly in square centimeters. In 14 patients (ten with associated mitral regurgitation), mitral orifice area was measured both by echocardiography and directly at time of operation. In 12 of 14 (86%) patients, mitral orifice area by two-dimensional echocardiography was within 0.3 square centimeters of that measured at operation (correlation coefficient for all 14 patients equals 0.92). We conclude that two-dimensional echocardiography is extremely useful in the evaluation of patients with mitral valve disease because it provides a noninvasive method for directly measuring the mitral valve orifice area that is accurate even in the presence of mitral regurgitation.

Calcinosis↗
PubMed1975

Identification of congenital malformations of the great arteries in infants by real-time two-dimensional echocardiography.

Real-time, two dimensional echocardiography was used to identify great artery relations in 23 infants and small children, including 16 patients with angiography documented transposition of the great arteries, tetralogy of Fallot, or pulmonary aresia. Using this technique, the heart was scanned perpendicular to its long axis at the origin of the great arteries. Great arteries cross-sectioned perpendicular to their long axes appear as circles; when sectioned longitudinally these arteries appeared as elongated sausage-shaped structures. I- patients with normally related great arteries, a curcular structure (aorta) always was positioned posterior to an elongated, sausage-shaped structure (distal right ventricular outflow tract and proximal main pulmonary artery). In transposition of the great arteries, two adjacent circular structures were observed; the anterior circle (aorta) was located to the right, left or directly anterior to the posterior circle (pulmonary artery). In pulmonary atresia or hypoplasis, a large posterior circle (aorta) was associated with an anteriorly positioned structure that was either short and small (atretic right ventricular outflow tract) or elongated with an area of severe narrowing (hypoplastic right ventricular outflow tract). Thus, real-time two-dimensional echocardiography provides a rapid, noninvasive means of accurately identifying congenital malformations of the great arteries in infants and small children and may be a useful adjunct to cardiac catheterization in the diagnosis of cyanotic congenital heart disease.

Child, Preschool↗
PubMedDate not supplied

Concurrent medical illness in the schizophrenic patient. Epidemiology, diagnosis, and management.

The management of the medically ill schizophrenic patient presents a dual dilemma for the physician. The patient may have a serious medical illness that must be diagnosed and effectively treated, yet the patient's psychiatric disorder may interfere with effective management. Thus, undiagnosed and untreated medical illness can result in significant morbidity for schizophrenic patients. Because schizophrenic patients may appear to be less cooperative than medical patients without concurrent psychiatric illness, they can cause countertransference reactions on the part of physicians and nursing staff that can interfere with treatment. Schizophrenic patients also have deficits in the processing of sensory information. These deficits require the staff to make changes in management in order to facilitate the patient's ability to cooperate with treatment and to give reliable informed consent. A host of other factors complicate the medical management and treatment of schizophrenic patients. Such factors include medication side effects of psychotropic medication, the potential interactions between medications used to treat the patient's physical illness with psychotropics, pregnancy in the female patient, and the strength of the patient's support system. The ability to successfully diagnose and treat concurrent medical illness in the schizophrenic patient will depend on the physician's ability to be flexible and to understand the implications of the patient's underlying disorder for his relationship to hospital staff. This paper reviews some of the relevant literature and describes possible treatment strategies integrating what we know about schizophrenia with medical management.

Adult↗
PubMedDate not supplied

Schizophrenia and nicotinic receptors.

Patients with schizophrenia often cannot respond to important features of their environment and filter out irrelevant stimuli. This dysfunction could be related to an underlying defect in inhibition--i.e., the brain's ability to alter its sensitivity to repeated stimuli. One of the neuronal mechanisms responsible for such inhibitory gating involves the activation of cholinergic nicotinic receptors in the hippocampus. These receptors are diminished in many specimens of hippocampal brain tissue obtained postmortem from schizophrenic patients. In living schizophrenic patients, stimulation of cholinergic receptors by nicotine transiently restores inhibitory gating of evoked responses to sensory stimuli. Many people with schizophrenia are heavy smokers, but the properties of the nicotinic receptor favor only short-term activation, which may explain why cigarette smoking is only a transient symptomatic remedy. This paper reviews the clinical phenomenology of inhibitory gating deficits in people with schizophrenia, the neurobiology of such gating mechanisms, and the evidence that some individuals with the disorder may have a heritable deficit in the nicotinic cholinergic receptors involved in this neurobiological function. Inhibitory gating deficits are only partly normalized by neuroleptic drugs and are thus a target for new therapeutic strategies for schizophrenia.

Antipsychotic Agents↗
PubMedDate not supplied

The pulsed Doppler ultrasound flowmeter: experimental evaluation of velocity accuracy and range resolution.

Accurate quantitation of blood flow patterns, particularly in the physiological state, is important to the successful study of several problems in biomedical research. The pulsed Doppler ultrasonic flowmeter offers promise of overcoming some of the difficulties present in other methods. This flowmeter can be either implantable or noninvasive. Although a number of papers describe important design criteria, the design or selection of a Doppler system for a given task remains a complex matter involving many compromises based on theoretical considerations and very limited data. Experimental data from well-defined flows are needed to help identify those areas in which ultrasonic flowmeters can be most useful. This paper defines and evaluates two important parameters for the pulsed Doppler ultrasonic flowmeter by comparing experimental results with those predicted theorectically. The first parameter is velocity accuracy; the second parameter is range resolution. Findings show that centerline flow velocities in circular tubes can be estimated to within a few percent of the correct value, and that a 1.5-mm range resolution can be realized with the system tested.

Blood Flow Velocity↗