Search PubMed⌕ Search

Biomedical subjects

E Garcia

Publications and source records attributed to E Garcia.

At least 217 records · Page 12Linked to original sources
PubMed1982

Premature closure of prosthetic mitral valves as a consequence of gravity.

To determine the influence of gravity on premature closure of prosthetic mitral valves, we studied 17 patients in whom this phenomenon had been observed during routine examination. All patients were in atrial fibrillation and none had aortic incompetence. Patients were studied in multiple positions by means of simultaneous echocardiography, phonocardiography, and cinefluoroscopy. In all patients premature closure was observed when the atrial side of the prosthesis was below the ventricular side, resulting in a downward motion of the occluder inside the valve cage. When patients were studied in positions in which the atrial side of the valve was higher that the ventricular side, premature closure never occurred, even during extremely prolonged diastolic periods. Since minor positional changes, which were found to determine whether premature closure occurred or not, are unlikely to produce significant alterations in pressure and flow across the mitral orifice during diastole, we conclude that position-dependent premature closure of prosthetic mitral valves in patients with atrial fibrillation is best explained by the effect of gravity on the prosthetic occluder. Examination of such patients in multiple positions should be helpful in distinguishing premature valve closure caused by aortic regurgitation from gravity-related presystolic closure. Inability to produce premature closure in patients in whom it had previously been demonstrated in the presence of similar R-R intervals may even prove useful in diagnosing new orifice obstruction.

Atrial Fibrillation↗
PubMed1982

Initial diastolic indentation of the mitral valve in aortic insufficiency.

An abnormal diastolic indentation of the mitral valve has been noted on short-axis two-dimensional echocardiograms in patients with aortic insufficiency. In order to assess the clinical usefulness of this finding, we reviewed the echocardiograms of 18 patients with this lesion who had undergone cineaortography. Results were compared with those of a control group of 100 patients. Initial diastolic indentation of the anterior mitral leaflet occurred in 8 of 12 patients with 3+ to 4+ aortic insufficiency. None of the patients with lesser regurgitation and no patients from the control group demonstrated this pattern. The presence of this abnormality appears to be a specific indicator of critical aortic insufficiency.

Adolescent↗
PubMed1982

Choline-containing bacteriophage receptors in Streptococcus pneumoniae.

Choline-containing teichoic acid seems to be essential for the adsorption of bacteriophage Dp-1 to pneumococci. This conclusion is based on the following observations: In contrast to pneumococci grown in choline-containing medium, cells grown in medium containing ethanolamine or other submethylated aminoalcohols instead of choline were found to be resistant to infection by Dp-1. Live choline-grown bacteria and heat- or UV-inactivated cells and purified cell walls prepared from these cells were capable of adsorbing phage Dp-1; ethanolamine-grown pneumococci or cell wall preparations were unable to do so. Adsorption of Dp-1 to choline-containing cell walls was competitively inhibited by phosphorylcholine and by several choline-containing soluble cell surface components, such as the Forssman antigen and the teichoic acid-glycan complexes formed by autolytic cell wall degradation. Cell walls prepared from pneumococci grown in ethanolamine or phosphorylethanolamine were inactive. Electron microscopic studies with pneumococci that had segments of choline-containing cell wall material amid ethanolamine-containing regions indicated that the Dp-1 phage particles adsorbed exclusively to the choline-containing surface areas. We suggest that the choline residues of the pneumococcal teichoic acid are essential components of the Dp-1 phage receptors in this bacterium.

Adsorption↗
PubMed1982

The noninvasive diagnosis of coronary artery disease in patients with left bundle-branch block.

The prognosis in patients with left bundle-branch block (LBBB) is related primarily to the presence or absence of underlying cardiac disease. Because coronary artery disease (CAD) is the most common underlying disease found in these patients, it would be desirable, in the presence of LBBB, to have a noninvasive method of differentiating between patients with and without CAD. We reviewed our experience in patients with LBBB who had undergone coronary arteriography with regard to electrocardiographic (ECG) stress testing, exercise radionuclide ventriculography (RNV), and exercise thallium scintigraphy; we also reviewed their clinical histories. A clinical history of typical angina pectoris was specific for CAD, a false-positive history being present in only one of 12 patients without CAD. The frequency of a positive ECG ST response to exercise was equal in patients with and without CAD. False-positive ejection fraction and wall-motion responses to exercise were frequent by RNV. A modification of the usual RNV criteria for positivity improved specificity but resulted in poor sensitivity for CAD. False-positive thallium study results also were. frequent in these patients. The perfusion defects usually involved the ventricular septum; the inferior and posterior walls were involved only in patients with CAD. We conclude that the usual noninvasive diagnostic tests for CAD are of limited value in patients with LBBB.

Journal Article↗
PubMed1982

Noninvasive assessment of the Ionescu-Shiley pericardial xenograft in the mitral position: preliminary experience.

To establish noninvasive criteria for assessment of the Ionescu-Shiley pericardial xenograft in the mitral position, 29 patients with a normally functioning bioprosthesis were studied with m-mode echocardiography and phonocardiography. Two-dimensional echocardiograms were also obtained in ten of the patients. Although two-dimensional echocardiography provided simultaneous visualization of a greater number of stents and leaflets than the m-mode technique, the superior resolution of m-mode ultrasound permitted more detailed analyses of the xenograft's motion patterns. The anterior leaflet, recorded in all patients, had an average excursion of 1.2 +/- 0.22 cm. Leaflet thickness measured 4 mm or less. Coarse diastolic vibration of the anterior leaflet was recorded in two patients in the absence of both aortic insufficiency and prosthesis dysfunction. Ultrasonic estimates of prosthesis height and orifice diameter did not correlate with micrometer measurements, possibly due to the limited resolution of pulsed ultrasound in the presence of a highly reflective substance. Opening and closing of the pericardial leaflets were associated with the production of high frequency vibrations on the phonocardiogram. The potential usefulness and limitations of echocardiography for evaluating the function of bioprosthetic valves are discussed.

Journal Article↗
PubMed1982

Post-exercise potentiation of wall motion to identify myocardial viability.

Resting left ventricular wall motion abnormalities may represent myocardial scars or areas of viable muscle which are ischemic and may thus benefit from revascularization surgery. Improvement in wall motion in the 3-6 minute post-exercise recovery period as compared to the resting state was investigated as a possible criterion to predict myocardial viability in 168 patients with coronary artery disease. Of 125 patients with abnormal resting wall motion, 14 of 14 who improved regional function post-exercise also improved following coronary bypass surgery. However, wall motion improved postoperatively in an additional 55 patients who had not demonstrated post-exercise improvement. An increase in ejection fraction post-exercise occurred in patients with coronary disease as well as an additional group of 24 normal subjects. Thus in the post-exercise period, improvement in resting wall motion is a highly specific but insensitive predictor of myocardial viability.

Journal Article↗
PubMed1981

Real time computerization of two-dimensional echocardiography.

A computerized system was developed for real time acquisition, enhanced processing, analysis, and display of cross-sectional images of the left ventricle derived by two-dimensional echocardiography (2DE). The new methodology couples a standard medical imaging computer system to the video output of any current 2DE unit, uses a 128 x 128 or 64 x 64 matrix window and stores the real time 30 frames/sec digitized images on a magnetic disk. Computerized beat-to-beat and frame-by-frame processing employs space-time smoothing the automatic detection of endocardial interfaces by standard threshold and second derivative techniques. Multiple views are displayed in real time with 256 levels of gray and color. The methodology was used to analyze and graphically display frame-by-frame changes throughout the cardiac cycle. In addition, regional wall motion and thickness were analyzed in 12 sectors of individual cross-sections using a standardized angular subdivision originating at the center of area and indexed by an external reference point. An algorithm was developed to correct cross-sectional interference definition from the commonly used trailing-to-leading edge to the more valid leading-to-leading outline technique. Computerized analysis of spatial and temporal variations of cardiac contraction were demonstrated in several clinical and experimental applications, including bicycle exercise testing, investigation of acute myocardial infarction, and assessment of interventions. Initial evaluation indicates that the new real time computerized digital acquisition and data analysis represents a major advances toward quantitation of left ventricular function using 2DE.

Animals↗
PubMed1981

Respiratory variation in Frank vectorcardiography and echocardiography in children.

Forty pediatric patients underwent echocardiographic and Frank vectorcardiographic studies during normal respiration. The right ventricular minor axis (RVEDD) increased significantly with inspiration (p less than 0.005), while the left ventricular minor axis did not significantly change. The distance from the anterior chest wall to the center of the left ventricle did significantly increase with inspiration (p less than 0.005). Some vectorcardiographic parameters changed with inspiration, also. Both the maximal spatial vector to the left (MSVL) and the X to the left (X-L) significantly decreased with inspiration. Although the average magnitude of these changes was small (10-15%), there was wide variation. Five of twenty-one patients with left ventricular hypertrophy during expiration had a clearly normal Frank VCG during inspiration. It is suggested that phases of respiration should be monitored when evaluating the Frank VCG in pediatric patients.

Adolescent↗
PubMed1981

Skin window immune response to normal human IgG in patients with rheumatoid arthritis and acute poststreptococcal glomerulonephritis.

The skin window technic was utilized to determine the reactivity of patients with rheumatoid arthritis (RA) and acute poststreptococcal glomerulonephritis (APSGN) to human IgG (H-IgG). The response to H-IgG was compared in nine patients with RA, 20 patients with APSGN, and 10 normal individuals. All subjects were tested concomitantly with the saline solution used as solvent for H-IgG. The normal controls and five patients were challenged, in addition, with diphtheria-tetanus-pertussis antigen (DPT) to which they had previous prophylactic exposure. The following results were obtained: 1) Four patients with RA and nine patients with APSGN responded with increased lymphocyte migration (more than 2 SD above the normal mean level) at nine and 12 hours. 2) The mean estimated immunogenic lymphocytosis (calculated subtracting the lymphocyte counts of the saline skin windows) of both patient groups was significantly higher than that of controls at the same time intervals. 3) The response of normal individuals and patients to DPT was comparable in time of appearance and intensity to the response of patients to H-IgG. Our studies that patients with RA and APSGN respond to H-IgG in a manner comparable to that observed with a known antigenic stimulus and support a clinical role for antiglobulin reactivity.

Adolescent↗
PubMed1981

Space/time quantitation of thallium-201 myocardial scintigraphy.

A comprehensive method is described for quantitation of the spatial distribution of TI-201 in the myocardium and its changes with time. The method, applied here to 51 patients, uses bilinear interpolative background subtraction to compensate for tissue crosstalk, and circumferential profiles to quantitate the relative radionuclide activity in the myocardium as an angular function with origin at the center of the left-ventricular cavity. In addition, washout circumferential profiles are calculated as percent washout from the stress circumferential profiles. Abnormal thallium distribution or washout is identified by automatic computer comparison of each patient's profiles with the corresponding limits of normal profiles, determined from the pooled profiles of 31 normal patients. In these 31, the computer output was normal in all cases. In 20 patients with angiographically documented coronary artery disease, 19 were determined to be abnormal by this method. This new computerized treatment provides accurate objective assessment of the presence of coronary artery disease.

Adult↗
PubMed1980

Mammary carcinoma--multidisciplinary treatment with bilateral mastectomy and immediate reconstruction.

The classical concepts pertaining to the natural history of mammary carcinoma and its treatment must be reviewed if survival rate is to be improved. By the time diagnosis is established, a fair amount of cases of carcinoma of the breast present distant, clinically undetectable micrometastases, which will not be affected by local therapy (surgery or radiation). Increasing evidence shows that mammary carcinoma nowadays must be looked upon as a diffuse disease affecting both breasts. Postoperative radiation does not improve the 5- and 10-year survival rates and has a negative effect upon the immunological defense of the patient. Immunology plays an important role in the evolution and cure of the patient with carcinoma of the breast. The mutilation produced by radical or ultraradical mastectomy may throw the patient into mental depression which, as a consequence, may decrease the immunological competence of the patient. Multiple drug chemotherapy, started at the time of surgery and continued for several months thereafter, may kill micrometastases. Preventive immunotherapy seems to be beneficial to the patient in attempting control of metastases.

Breast Neoplasms↗
PubMed1980

Interactions of homologous and heterologous deoxyribonucleic acids and competent Bacillus subtilis cells.

Glucosylated and nonglucosylated bacteriophage T4 deoxyribonucleic acids (DNAs) are able to bind to competent cells of Bacillus subtilis, although the former does so in a rather unstable fashion, probably because of the glucosylation. Several heterologous DNAs compete with homologous DNA for the same receptors in binding and in transformation. A different pattern in competition for DNA binding was observed for homologous and T4 glucosylated DNAs in intact cells as compared with protoplasts or membrane vesicles. The results are consistent with the existence of two types of receptor sites on the membrane of competent B. subtilis cells.

Bacillus subtilis↗
PubMed1980

Is postextrasystolic potentiation dependent on Starling's law? Biplane angiographic studies in normal subjects.

The cineangiograms of 26 normal subjects were analyzed to study the effect of Starling's mechanism on postextrasystolic potentiation. The end-diastolic volumes (single plane and biplane) of the left ventricle were similar in the regular sinus beat before an extrasystole and sequential sinus beats after an extrasystole. However, the ejection fraction, mean normalized systolic ejection rate, mean velocity of fiber shortening and long-axis shortening were consistently larger in the first sinus beat after an extrasystole. We conclude that postextrasystolic potentiation is independent of left ventricular end-diastolic volume in normal human hearts and the compensatory pause after an extrasystole does not result in increased end-diastolic volume.

Angiography↗
PubMed1980

Prolonging life with coronary bypass surgery in patients with three-vessel disease.

In this study we examined survival after coronary bypass surgery in patients with three-vessel disease. First, survival data were analyzed from selected of patients who had a poor prognosis without surgery; second, data were analyzed in subsets classified by severity of disease. The data strongly suggest that patients with three-vessel disease, especially patient with a poor medical prognosis, benefit from coronary bypass surgery.

Actuarial Analysis↗