Search PubMed⌕ Search

Biomedical subjects

E Foster

Publications and source records attributed to E Foster.

At least 55 records · Page 3Linked to original sources
PubMed1997

Acute hypovolemia may cause segmental wall motion abnormalities in the absence of myocardial ischemia.

UNLABELLED: New segmental wall motion abnormalities (SWMA) detected by echocardiography are considered sensitive and specific markers of myocardial ischemia. However, we have observed new SWMA during pacing-induced reductions in left ventricular filling, which resolved immediately with cessation of the atrial pacing and simultaneous restoration of filling. Therefore, we designed this study to determine whether acute reduction in filling can induce new SWMA in the absence of ischemia. Institution of cardiopulmonary bypass was used as a clinical model of acute reduction in filling, and a beat-by-beat analysis of left ventricular contraction, filling, blood pressures, and electrocardiogram was performed when the drainage of blood to the cardiopulmonary bypass machine rapidly emptied the heart. Acute reduction in filling induced new SWMA in 4 of 38 study patients. All 4 patients had preexisting abnormalities of left ventricular contraction, but translocation of these preexisting SWMA did not explain the new SWMA, nor did myocardial ischemia. We conclude that acute reduction in left ventricular filling can cause new SWMA in the absence of ischemia. This finding limits the usefulness of new SWMA as a marker of ischemia in the presence of acute reduction in filling, such as that secondary to severe hypovolemia. IMPLICATIONS: This study documented that acute reduction in cardiac filling can be associated with new systolic wall motion abnormalities detected by transesophageal echocardiography in the absence of documented myocardial ischemia. These findings indicate that segmental wall motion may not be a valid marker for ischemia in the setting of acute hypovolemia.

Blood Pressure↗
PubMed1996

Detection of intraoperative segmental wall-motion abnormalities by transesophageal echocardiography: the incremental value of additional cross sections in the transverse and longitudinal planes.

Because biplane and multiplane transesophageal echocardiography (TEE) are more complex and expensive than single-plane TEE, we performed this study to determine whether the use of multiple single-plane (transverse) cross sections is as reliable for detection of left ventricular segmental wall-motion abnormalities (SWMA) as biplane TEE. We used biplane TEE to acquire nine standard cross sections of the left ventricle in 41 consecutive adults undergoing cardiac or vascular surgery. Six of these cross sections were in the transverse plane (i.e., achievable with single-plane TEE) and three in the longitudinal plane (i.e., achievable only with biplane or multiplane TEE). Each cross section was divided into myocardial segments for analysis. A total of 1810 segments were analyzed by independent investigators using a standardized evaluation system. Seventeen percent of all SWMA detected in this study were in the midpapillary transverse-plane cross section, an additional 48% in other transverse-plane cross sections, and 35% exclusively in the longitudinal-plane cross sections. Thus, most (65%), but not all, SWMA were in cross sections achievable with single-plane TEE. We conclude that the MP-T cross section should be the foundation for assessment of segmental function, but additional cross sections in the transverse and longitudinal planes are required for detection of the majority of segmental wall-motion abnormalities.

Adult↗
PubMed1996

Prediction of outcome for critically ill patients with unexplained hypotension.

OBJECTIVES: To determine the clinical variables that affect the prognosis of critically ill patients with sustained unexplained hypotension. A further goal was to develop a prognostic scoring system based on clinical data available at the onset of hypotension. DESIGN: Prospective cohort study. SETTING: The intensive care units (ICUs) of an academic medical center. PATIENTS: One hundred one adult ICU patients with sustained (> 60 mins) unexplained hypotension. Using the initial 50 patients (derivation set), a prognostic score was developed that was then tested in the next 51 patients (validation set). INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: The main outcome variable was death or hospital discharge. The overall hospital mortality in the combined sets was 58%. Using a multivariable model we identified three independent (p < .05) predictors of hospital mortality, including the Acute Physiology and Chronic Health Evaluation (APACHE) II score at the time of hypotension, the time from hospital admission to hypotensive episode, and hospital admission for surgery or treatment of malignancy. These variables were weighted and combined to create a Hypotension Score which separated patients in the combined sets into three prognostic groups: a) Hypotension Score of < 40, mortality 7%, (n = 27); b) Hypotension Score of 40 to 64, mortality 70%, (n = 50); and c) Hypotension Score of > or = 65, mortality 92%, (n = 24). The area under the receiver operating characteristic curve was .85 for the derivation set and .83 for the validation set vs. .76 for the APACHE II score alone. CONCLUSIONS: The prognosis of hypotension in the critical care setting is highly variable, but can be predicted from patient characteristics.

APACHE↗
PubMed1996

Immediate effects of intravenous cocaine on the thoracic aorta and coronary arteries. A transesophageal echocardiographic study.

UNLABELLED: STUDY OBJECTIVES AND DESIGN: Arterial vasoconstriction is thought to play a role in the etiology of cocaine-induced cardiovascular complications, but little is known about the immediate effects of cocaine on the thoracic aorta and coronary arteries. To examine these effects, we used transesophageal echocardiography to examine the thoracic aorta and coronary arteries before and immediately after intravenous (i.v.) cocaine (1.2 mg/kg) in 15 subjects. MEASUREMENTS AND RESULTS: Immediately after cocaine infusion, average heart rate, systolic BP, and double product were increased compared with baseline (22%, 15%, 35%, respectively). There was no significant change in the diameters of the ascending aorta (27.5 vs 27.1 mm; p = 0.85), the descending aorta (19.8 vs 20.4 mm; p = 0.62), or the left main coronary artery (4.3 vs 4.7 mm; p = 0.15). However, there was a trend for an increase in coronary blood flow immediately after cocaine (226 vs 309 mL/min; p = 0.10). CONCLUSIONS: We conclude that in the 15 subjects studied, there was no evidence of thoracic aorta of coronary artery vasoconstriction immediately after i.v. cocaine. Instead, we found that the diameters of the thoracic aorta and the left main coronary artery were unchanged, and that there was a trend for augmentation of coronary artery blood flow.

Adult↗
PubMed1995

TrkB-like immunoreactivity in trigeminal sensory nerve fibers of the rat molar tooth pulp: development and response to nerve injury.

The localization of TrkB, a signal transducing receptor for brain-derived neurotrophic factor and neurotrophin-4, was studied in the rat mandibular molar pulp during development and following nerve injury. Sections were incubated with rabbit polyclonal antiserum against the catalytic part of the TrkB receptor, thus only binding to full-length TrkB receptors, and examined by immunofluorescence microscopy and EM immunocytochemistry. At embryonic day 17, strongly TrkB-positive fibers were located in mandibular nerve trunks, in nerve fibers of deeper mesenchyme in close spatial relation to sites of future tooth development and in subepithelial nerve plexa. At postnatal days 1-12 intensely TrkB-positive nerve fibers surrounded and eventually invaded the developing dental papillae and pulps. In the normal adult pulp TrkB-immunoreactive axons were seen extending through the radicular pulp into the coronal areas. Double labelling demonstrated a considerable overlap between TrkB-like immunoreactivity and low affinity neurotrophin receptor-like immunoreactivity in the pulp, although some low affinity neurotrophin receptor-positive nerve fibers lacked TrkB-like immunoreactivity. Immunogold electron microscopy showed TrkB-like immunoreactivity in myelinated as well as in unmyelinated axons. One week following inferior alveolar nerve injury there was a dramatic decrease in the level of TrkB-like immunoreactivity labelling in the pulp, which paralleled an increase in the expression of Schwann cell low affinity neurotrophin receptor-like immunoreactivity. The first signs of regenerating TrkB-positive nerve fibers were found at 4 weeks post-operative, and at 9 weeks the distribution of pulpal TrkB-like immunoreactivity had returned to normal. These data indicate that brain-derived neurotrophic factor and/or neurotrophin-4 could be target-derived factors involved in sensory trigeminal tooth pulp nerve fiber development, differentiation or regeneration.

Aging↗
PubMed1995

Evaluation of mitral stenosis with velocity-encoded cine-magnetic resonance imaging.

Velocity-encoded cine-magnetic resonance imaging (VEC-MRI) is a new method for quantitation of blood flow with the potential to measure high-velocity jets across stenotic valves. The objective of this study was to evaluate the ability of VEC-MRI to measure transmitral velocity in patients with mitral stenosis. Sixteen patients with known mitral stenosis were studied. A 1.5 Tesla superconducting magnet was used to obtain velocity-encoded images in the left ventricular short-axis plane. Images were obtained throughout the cardiac cycle at 3 consecutive slices beginning proximal to the mitral coaptation point. To determine the optimal slice thickness for MRI imaging, both 10 mm and 5 mm thicknesses were used. Echocardiography including continuous-wave Doppler was performed on every patient within 2 hours of MRI imaging. Peak velocity was determined for both VEC-MRI and Doppler-echo images. Two observers independently measured the VEC-MRI mitral inflow velocities. Of the 16 patients, imaged data were incomplete in only 1 study, and all images were adequate for analysis. Strong correlations were found for measurements of mitral valve gradient for both 10 mm (peak r = 0.89, mean r = 0.84) and 5 mm (peak r = 0.82, mean r = 0.95) slice thicknesses. Measurements of peak velocity with VEC-MRI (10 mm) agreed well with Doppler: mean 1.46 m/s, mean of differences (Doppler MRI) 0.38 m/s, standard deviation of differences 0.2 m/s. These findings suggest that VEC-MRI can noninvasively determine the severity of mitral stenosis.

Adult↗
PubMed1995

Segmental analysis of resting echocardiographic function and stress scintigraphic perfusion: implications for myocardial viability.

In 73 patients with coronary artery disease, we performed segmental analysis of resting two-dimensional echocardiography and stress thallium-201 single photon emission computed tomographic scintigraphy with 24-hour delayed imaging to test the hypotheses that (1) combined analysis of stress thallium-201 scintigraphy (with 24-hour redistribution) and echocardiography provides an evaluation of the viability of most myocardial segments; and (2) the severity of the scintigraphic perfusion abnormality in a given segment is equivalent to the severity of its echocardiographically determined functional impairment. Scintigraphy showed 14% of the 1168 segments analyzed to have fixed severe defects. Echocardiography showed 11% of the 1070 segments analyzed to be akinetic or dyskinetic. However, with combined analysis, only 62 (5%) segments showed no evidence of viability by either imaging technique. We conclude that in this group of patients, 95% of segments have evidence of viability by one of these two conventional imaging techniques.

Aged↗
PubMed1995

Abnormal pulmonary artery pressure profile after cardiac transplantation: an exercise Doppler echocardiographic study.

This study was designed to test the hypothesis that pulmonary artery pressure at rest and during exercise differs between patients with a transplanted heart and normal subjects and to determine the mechanisms responsible for the difference. Twenty-one patients who had undergone heart transplantation 1.5 to 27 months earlier without current evidence of acute cardiac rejection and 25 normal subjects were studied by exercise Doppler echocardiography. Systolic pulmonary artery pressure was higher at baseline in heart transplant patients than in normal subjects, at 31.6 +/- 9 mm Hg (mean +/- SD) versus 22.5 +/- 4, respectively (p = 0.0001). The increase in systolic pulmonary artery pressure with exercise was 1.4 times higher in heart transplant patients and correlated with pretransplantation pulmonary vascular resistances (r = 0.55; p = 0.01). In contrast, cardiac index at baseline or during exercise did not differ between the two groups. Diastolic parameters and ejection fraction at baseline or during exercise did not correlate with systolic pulmonary artery pressure. In conclusion, Doppler exercise echocardiography offers an alternative, safe method hemodynamic study of the transplanted heart. Although an abnormal increase in left ventricular filling pressure with exercise has been well documented, further studies are needed to investigate and characterize potential abnormalities in pulmonary vascular tone in the transplanted heart.

Adult↗
PubMed1995

Transesophageal echocardiography predicts mortality in critically ill patients with unexplained hypotension.

OBJECTIVES: This study sought to determine the prognostic yield and utility of transesophageal echocardiography in critically ill patients with unexplained hypotension. BACKGROUND: Transesophageal echocardiography is increasingly utilized in the intensive care setting and is particularly suited for the evaluation of hypotension; however, the prognostic yield of transesophageal echocardiography in these patients is unknown. METHODS: We prospectively studied 61 adult patients in the intensive care unit with sustained (> 60 min) unexplained hypotension. Both transthoracic and transesophageal echocardiography were performed, and results were immediately disclosed to the primary physician, who reported any resulting changes in management. Patients were classified on the basis of transesophageal echocardiographic findings into one of three prognostic groups: 1) nonventricular (valvular, pericardial) cardiac limitation to cardiac output; 2) ventricular failure; and 3) noncardiac systemic disease (hypovolemia or low systemic vascular resistance, or both). Primary end points were death or discharge from the intensive care unit. RESULTS: A transesophageal echocardiographic diagnosis of nonventricular limitation to cardiac output was associated with improved survival to discharge from the intensive care unit (81%) versus a diagnosis of ventricular disease (41%) or hypovolemia/low systemic vascular resistance (44%, p = 0.03). Twenty-nine (64%) of 45 transthoracic echocardiographic studies were inadequate compared with 2 (3%) of 61 transesophageal echocardiographic studies (p < 0.001). Transesophageal echocardiography contributed new clinically significant diagnoses (not seen with transthoracic echocardiography) in 17 patients (28%), leading to operation in 12 (20%). CONCLUSIONS: Transesophageal echocardiography makes a clinically important contribution to the diagnosis and management of unexplained hypotension and predicts prognosis in the critical care setting.

Adult↗
PubMed1995

Congenital heart disease in adults.

Patients reaching adulthood with unoperated and operated congenital heart disease require attention to issues of exercise, antibiotic prophylaxis, contraception, and pregnancy. A careful clinical history is important to establish the degree of a person's disability, if any, and the symptoms responsible for the disability, whether due to heart failure, cyanosis, or both. The findings of a physical examination and a noninvasive evaluation, including electrocardiogram, chest x-ray film, and echocardiography, are often sufficient to establish a diagnosis and to assess the adequacy of a previous operation. Transesophageal echocardiography and magnetic resonance imaging are adjunctive procedures that are indicated when routine transthoracic echocardiography is limited. Cardiac catheterization may be necessary when the noninvasive data are ambiguous and to assess coronary artery disease (congenital and acquired) in patients considered for surgical therapy. Cardiac catheterization is increasingly therapeutic (such as percutaneous pulmonary balloon valvuloplasty) as well as diagnostic. Primary surgical repair or additional surgical palliative procedures should be considered in symptomatic adults. A patient with Eisenmenger's syndrome--severe pulmonary hypertension--is a special case that may be amenable only to transplantation.

Adult↗
PubMed1995

Three-dimensional transabdominal ultrasound identification of aortic plaque.

Tree-dimensional (3-D) reconstruction of acquired tomographic images in adults has recently been described. With an adaptation of this technique, we performed 3-D reconstruction of transabdominal images of the abdominal aorta to test the hypotheses that 3-D reconstruction of the abdominal aorta is feasible and that 3-D images have incremental value over 2-D in the detection of atheromatous plaque. Twenty-one patients undergoing contrast aortography (Aogram) for clinical indications (1 abdominal aorta (AA) aneurysm, 5 peripheral vascular disease, 1 renal artery stenosis, 14 renal donors) were studied using a 5-MHz annular array probe fitted to a mechanical registration device. In 13 of 21 patients, adequate 2-D ultrasound slices were acquired around a 180 degrees rotation and stored as a volumetric data set using a dedicated computer and 3-D images were reconstructed off-line. Three-dimensional and planar images were blindly compared with Aograms using the following scale: grade 1, normal; grade 2, increased echodensity of the intimal surface; grade 3, local intimal thickening and/or luminal irregularity; and grade 4, protruding mass. Analogous 3-D images were produced in all 13 patients with branching vessels visible in 3 of 13. In 10 patients, the Aogram was interpreted as normal. Compared with Aogram, blindly interpreted 3-D images were compared and correctly identified normal AA in 8 of 10 and atherosclerotic plaque (grade 3 or 4) in 2 of 3. Discordant results were present in 2 of 10 normal aortas and 1 of 3 disease aortas. When 2-D (planar) images were compared with Aograms, 8 of 10 identified normal AA and 3 of 3 aortas with grade 3 or 4 plaque. Thus, in 2 patients, 3-D and planar images suggested atherosclerotic changes not seen by Aogram. Transabdominal 3-D imaging of the abdominal aorta is a feasible technique. Early data suggest that 3-D imaging may distinguish normal from moderate to severe disease, but currently has no demonstrable incremental value over conventional 2-D images. These early results in a small number of patients suggest that this promising technique warrants further evaluation.

Adult↗
PubMed1994

trkB-like immunoreactivity in rat dorsal root ganglia following sciatic nerve injury.

The expression of full-length trkB protein, the functional high affinity receptor for BDNF and NT-4, was examined by immunohistochemistry in adult rat L4-L5 dorsal root ganglia after different types of sciatic nerve lesions. In normal ganglia, 52.5% of the neurons showed trkB-like immunoreactivity. Size measurements demonstrated that trkB-like immunoreactivity was seen predominantly in small- and medium-sized cells. This was confirmed by the finding that 28% of all trkB-positive neurons showed affinity to RT97, an antibody which labels a neurofilament epitope specific for medium-sized and large primary afferent neurons. After crush, section or neuroma formation of the sciatic nerve, the proportion of trkB-positive cells was 64.5%, 58% and 61.9%, respectively. Since trkB-receptors are present in regenerating primary afferent neurons, these data could indicate that BDNF and/or NT-4 are involved in sensory nerve fiber regeneration after adult injury.

Animals↗
PubMed1994

Quantification of mitral regurgitation by velocity-encoded cine nuclear magnetic resonance imaging.

OBJECTIVES: The feasibility of velocity-encoded cine nuclear magnetic resonance (NMR) imaging to measure regurgitant volume and regurgitant fraction in patients with mitral regurgitation was evaluated. BACKGROUND: Velocity-encoded cine NMR imaging has been reported to provide accurate measurement of the volume of blood flow in the ascending aorta and through the mitral annulus. Therefore, we hypothesized that the difference between mitral inflow and aortic systolic flow provides the regurgitant volume in the setting of mitral regurgitation. METHODS: Using velocity-encoded cine NMR imaging at a magnet field strength of 1.5 T and color Doppler echocardiography, 19 patients with isolated mitral regurgitation and 10 normal subjects were studied. Velocity-encoded cine NMR images were acquired in the short-axis plane of the ascending aorta and from the short-axis plane of the left ventricle at the level of the mitral annulus. Two independent observers measured the ascending aortic flow volume and left ventricular inflow volume to calculate the regurgitant volume as the difference between left ventricular inflow volume and aortic flow volume, and the regurgitant fraction was calculated. Using accepted criteria of color flow Doppler imaging and spectral analysis, the severity of mitral regurgitation was qualitatively graded as mild, moderate or severe and compared with regurgitant volume and regurgitant fraction, as determined by velocity-encoded cine NMR imaging. RESULTS: In normal subjects the regurgitant volume was -6 +/- 345 ml/min (mean +/- SD). In patients with mild, moderate and severe mitral regurgitation, the regurgitant volume was 156 +/- 203, 1,384 +/- 437 and 4,763 +/- 2,449 ml/min, respectively. In normal subjects the regurgitant fraction was 0.7 +/- 6.1%. In patients with mild, moderate and severe mitral regurgitation, the regurgitant fraction was 3.1 +/- 3.4%, 24.5 +/- 8.9% and 48.6 +/- 7.6%, respectively. The regurgitant fraction correlated well with the echocardiographic severity of mitral regurgitation (r = 0.87). Interobserver reproducibilities for regurgitant volume and regurgitant fraction were excellent (r = 0.99, SEE = 238 ml; r = 0.98, SEE = 4.1%, respectively). CONCLUSIONS: These findings suggest that velocity-encoded NMR imaging can be used to estimate regurgitant volume and regurgitant fraction in patients with mitral regurgitation and can discriminate patients with moderate or severe mitral regurgitation from normal subjects and patients with mild regurgitation. It may be useful for monitoring the effect of therapy intended to reduce the severity of mitral regurgitation.

Adult↗
PubMed1994

Evaluation of electrocardiographic criteria for right atrial enlargement by quantitative two-dimensional echocardiography.

OBJECTIVES: This study was conducted to evaluate the sensitivity and specificity of traditional electrocardiographic (ECG) criteria for right atrial enlargement and identify improve criteria, using quantitative two-dimensional echocardiography. BACKGROUND: Traditional ECG criteria for right atrial enlargement, such as P pulmonale, have been increasingly criticized as insensitive and nonspecific. Quantitative two-dimensional echo-cardiography has been shown to be a useful method for evaluating atrial size. METHODS: Hospitalized patients with mild, moderate and severe right atrial enlargement were selected from our laboratory's data base and compared with age- and gender-correlated hospitalized control subjects. After exclusions, 100 patients with right atrial enlargement and 25 control patients remained. Planimetric measurement of right atrial volumes was accomplished by two independent observers using the single-plane method of discs algorithm. Electrocardiograms were independently evaluated for current and newly proposed right atrial enlargement criteria. RESULTS: Fifty-two patients (52%) were in sinus rhythm, 41 were in atrial fibrillation, 5 were in atrial flutter, and 2 were in ectopic atrial rhythm. All control subjects were in sinus rhythm. The right atrial volume for the control group was 35.0 +/- 7.4 ml (mean +/- SD), with a narrow, roughly normal distribution. The right atrial volume for the patient group was 147.6 +/- 69.1 ml (median 127.2) in a wide, skewed distribution. The difference of mean values was highly significant (p = 0.0001). Right ventricular enlargement was found to some degree in all patients with right atrial enlargement. The most powerful predictors of right atrial enlargement were a QRS axis > 90 degrees, a P wave height in lead V2 > 1.5 mm and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. P pulmonale detected only 6% of patients with right atrial enlargement. CONCLUSIONS: Using quantitative two-dimensional echocardiography, we found that most previously reported ECG criteria for right atrial enlargement have low predictive power. The best predictors of right atrial enlargement were a P wave height > 1.5 mm in lead V2 and, as new criteria, a QRS axis > 90 degrees and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. Further studies are needed to prospectively validate these findings.

Atrial Function, Right↗
PubMed1994

Exercise Doppler echocardiography identifies abnormal hemodynamics in adults with congenital heart disease.

The hemodynamic factors contributing to reduced exercise capacity in adults with congenital heart disease are not fully defined. We hypothesized that they would demonstrate reduced exercise capacity compared with age-matched control subjects because of abnormal exercise hemodynamics and ventricular performance demonstrable by echocardiography. We retrospectively analyzed the results of all studies in all patients with congenital heart disease (from 1988 to 1993) and found that the peak work load and double product achieved were decreased in comparison with normal values (79 +/- 47 W vs 149 +/- 52 W [p < 0.0001] and 19,210 +/- 6805 vs 25,701 +/- 6440 [p = 0.005], respectively). Seven patients achieved work loads < 40 W associated with an exaggerated exercise pulmonary artery pressure response, decreases in right and/or left ventricular function with exercise, or both. Normal or near-normal exercise tolerance was observed in the following patient groups: (1) repaired tetralogy of Fallot, (2) uncomplicated I-transposition of the great arteries, and (3) Ebstein's anomaly with atrial septal defect. We conclude that exercise echocardiography provides new hemodynamic information for evaluating functional limitations in congenital heart disease.

Adolescent↗