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Biomedical subjects

A C Borges

Publications and source records attributed to A C Borges.

At least 55 records · Page 3Linked to original sources
PubMed1998

Autonomic effects of dipyridamole stress testing on frequency distribution of RR and QT interval variability.

Transient myocardial ischemia and associated changes in the autonomic nervous system may influence heart rate and ventricular repolarization to variable degrees. This study evaluated the effect of dipyridamole (DIP) induced ischemia on the autonomic balance by spectral analysis of RR and QT intervals variability. Patients with coronary artery disease undergoing DIP stress echocardiography were studied. From high resolution ECG recordings, RR and QT interval measurements were performed by a dynamic template-matching algorithm. A time-variant analysis was used to estimate power in the LF (0.05-0.15 Hz) and in the HF (0.15-0.4 Hz) band of RR and QT interval spectra. Patients were grouped in ischemic and nonischemic subgroups based on the echocardiographic detection of wall-motion abnormalities. In patients without ischemia (n = 28), DIP caused a decrease in LF power and an increase in HF power of the RR and QT interval variability, indicating concordant changes of both intervals. In contrast, patients with inducible ischemia (n = 11) showed a decrease in HF power of the RR interval spectra and an increase of HF power of QT interval spectra. Furthermore, LF power was increased for RR but decreased for QT interval spectra. Our study suggests that DIP induced ischemia causes a loss of autonomic coupling between heart rate and ventricular repolarization for sympathetic and parasympathetic activities. This lability in ventricular repolarization may constitute an arrhythmogenic substrate during acute ischemia in patients with coronary artery disease.

Algorithms↗
PubMed1997

Acute right-sided heart failure due to hemorrhage into a pericardial cyst.

This is a description of a rare complication of a pericardial cyst with spontaneous internal hemorrhage and following tamponade. The noninvasive diagnosis was done by transesophageal echocardiography and computed thoracic tomography. The cyst was thoracoscopically removed and pathologically examined. This case demonstrates a rare but important and life-threatening complication of mostly asymptomatic pericardial cysts.

Acute Disease↗
PubMed1997

Radiographic manifestations of multiple myeloma in the mandible: a retrospective study of 77 patients.

PURPOSE: This retrospective study was done to determine the frequency and radiographic pattern multiple myeloma in the mandible. PATIENTS AND METHODS: Seventy-seven patients with multiple myeloma were studied using skull and panoramic radiographs of the jaws made at the time of initial diagnosis. RESULTS: Skull manifestations were present in 46.7% and jaw manifestations in 15.6% of the cases studied. The pattern of jaw involvement was characterized by osteolytic lesions without other radiographic manifestations of bone involvement. There was no relationship between the pattern of jaw and extragnathic involvement and increased M-component of secreted immune globulin. Jaw involvement was largely unaccompained by oral symptoms. CONCLUSION: The results suggest that mandibular lesions are a common finding in multiple myeloma.

Adult↗
PubMed1997

Relationship between haemodynamics and morphology in pulmonary hypertension. A quantitative intravascular ultrasound study.

BACKGROUND: Intravascular ultrasound imaging of the pulmonary arteries has been demonstrated to be a reliable method of quantifying vessel diameter, luminal area and pulsatility. Simultaneous measurement of flow velocity and its response to vasodilators allows the relationship between morphology and functional compromise to be studied, especially endothelial dysfunction. METHODS: In 51 patients (mean age = 49.8 +/- 12.6 years, 17 female) we performed right heart catheterization and simultaneous intravascular ultrasound of pulmonary artery branches. The patients were divided in two groups: group 1 with normal pulmonary artery pressure and pulmonary vascular resistance, and group 2 with pulmonary hypertension (peak pulmonary artery pressure > 30 mmHg and/or mean pulmonary artery pressure > 20 mmHg). Vessel wall and lumen were studied using a 2.9 F intravascular ultrasound catheter with a 30 MHz phased array transducer. Measurement of blood flow velocity was accomplished by a Doppler flow wire (0.018 inch). The maximal flow change during acetylcholine infusion (adjusted to 10(-6); 10(-5), and 10(-4) M concentration in the blood vessel) was measured. RESULTS: There were no significant differences between groups 1 and 2 with respect to age (48.5 +/- 14.3 years vs 50.3 +/- 12.3 years; P = ns), gender (4 female/8 male vs 13 female/26 male; P = ns), luminal area of the vessel segment in which the intravascular ultrasound measurements were obtained (11.8 +/- 6.1 mm2 vs 16.7 +/- 14.3 mm2; P = ns), internal diameter (3.9 +/- 1.2 mm vs 4.2 +/- 1.7 mm; P = ns), and external diameter (6.1 +/- 1.3 mm vs 6.9 +/- 2.1 mm; P = ns). Cross-sectional images of the pulmonary artery wall demonstrated a single ring with high echodensity with a thin inner layer regarded as intima in group 1. In contrast, the majority of patients (n = 35/39) in group 2 demonstrated a thickening of the intimal layer and/or a disturbance of layering of the echogenic arterial wall. The relative wall thickness was higher in group 2 than in group 1 (22.5 +/- 10.4% vs 15.3 +/- 6.5%; P < 0.05). There were no significant correlations between pulmonary artery pressure and wall thickness pulmonary artery pressure and area change in the cardiac cycle, acetylcholine-dependent increase in pulmonary flow and morphological changes in the vessel wall. CONCLUSION: We conclude that intravascular ultrasound is capable of detecting morphological changes in the pulmonary vessel wall in pulmonary hypertension and that vessel wall hypertrophy of small pulmonary segment arteries, as detected by intravascular ultrasound, is not predictive of functional vasodilatory response of resistance vessels of the same vessel area.

Aged↗
PubMed1997

Respiratory muscle weakness and normal ventilatory drive in dilative cardiomyopathy.

BACKGROUND: In dilative cardiomyopathy several factors influence dyspnoea. Patients with chronic heart failure may demonstrate impairment of breathing pattern, ventilatory drive and respiratory muscle strength, as well as reduction of ventilatory efficiency. The purpose of this study was to evaluate whether dilative cardiomyopathy is accompanied by changes in breathing pattern, respiratory muscle weakness and ventilatory neural drive. METHODS: We investigated 47 patients (36 men, mean age = 47.8 +/- 11.2 years) with chronic heart failure due to dilative cardiomyopathy, and 30 healthy subjects (10 men, mean age = 35.4 +/- 11.7 years) served as controls. Patients and controls underwent evaluation of left ventricular ejection fraction by 2D echocardiography, spirometry, body plethysmography, mouth occlusion pressure and respiratory muscle strength, as well as by submaximal treadmill exercise testing with gas exchange measurements. The patients' results were compared to controls and predicted standard normal values, and evaluated for differences according to the degree of severity of functional impairment. RESULTS: Patients with dilative cardiomyopathy demonstrated a slight reduction in lung volumes (15% of the patients with obstructive and 15% with restrictive lung function pattern) and diffusion capacity (20.4 +/- 6.8 vs 15.4 +/- 6.7 ml.min-1.kPa-1; P < 0.01). In neural drive, as assessed by mouth occlusion pressure, there was no significant difference between patients and controls. There was a slight but significant reduction in respiratory muscle strength, as assessed by measuring maximal inspiratory pressure in patients with dilative cardiomyopathy (6.7 +/- 2.4 kPa vs 8.6 +/- 3.5 kPa; P < 0.01). The observed changes were more pronounced in the severe chronic heart failure patients (with a reduction in ventilatory efficiency) whereas no relationship among indices of cardiac or respiratory function was found. CONCLUSIONS: Patients with chronic heart failure due to dilative cardiomyopathy develop respiratory muscle weakness without changes in neural ventilatory drive, and slight changes in breathing pattern related to the severity of the disease.

Adult↗
PubMed1996

Preoperative two- and three-dimensional transesophageal echocardiographic assessment of heart tumors.

BACKGROUND: Two-dimensional transesophageal echocardiography is the most widely used diagnostic approach in the rare entity of heart tumors. The aim of this study was to assess the diagnostic usefulness of three-dimensional echocardiography in comparison with the two-dimensional technique in a rare clinical setting. METHODS: Twenty-seven patients (18 women; mean age, 49.7 +/- 14 years) with a histologically proven diagnosis of a cardiac tumor were studied. The primary diagnosis was done by a two-dimensional transthoracic echocardiography (n = 9) and transesophageal echocardiography (n = 18). In addition, we performed three-dimensional transesophageal assessment in 5 patients with left atrial myxomas. The echocardiographic findings were compared with the intraoperative appearance and pathologic diagnosis. RESULTS: The echocardiographically suspected diagnosis of a heart tumor in 29 cases was histologically correct in 27 patients (myxomas, 20; epicardial lipoma, 1; malignant epicardial mesothelioma, 1; metastatic processes of hypernephromas, 2; and undifferentiated tumors of the pericardium, 3). Only the combination of multiplane transesophageal and three-dimensional echocardiography was able to demonstrate the shape, dimensions, location, origin, surface, three-dimensional movement, and involvement of valves and was most useful in the preoperative diagnosis and planning. CONCLUSIONS: Three-dimensional transesophageal echocardiography yields important additional clinical information and improves the operative planning. Three-dimensional echocardiography may become the best approach to study the anatomy and pathology of the heart as it provides an objective display of cardiac size and shape in heart tumors.

Adult↗
PubMed1996

Diagnosis of alveolitis in interstitial lung manifestation in connective tissue diseases: importance of late inspiratory crackles, 67 gallium scan and bronchoalveolar lavage.

The diagnostic relevance of bronchoalveolar lavage (BAL) and associated non-invasive findings in connective tissue diseases (CTD) has not been established regarding alveolitis so far. The goal of the study was to determine the relations between BAL cell differential count and findings of non-invasive diagnostic procedures for alveolitis to predict the clinical value of BAL in CTD. One hundred-five patients (92 non-smokers; 13 smokers) with CTD (73 patients with systemic sclerosis, 19 with systemic lupus erythematosus, 13 with primary Sjögren's syndrome) had symptoms or signs of lung involvement and were further examined (lung function test, chest radiography, thoracic computed tomography, 67 gallium scintigraphy and BAL). The relations between BAL in middle lobe and cell count differentiation to non-invasive investigations were analyzed by logistic regression. In all CTD patients investigated a pulmonal involvement occurred based on non-invasive methods. Regarding non-invasive methods, alveolitis determined by BAL cell differential count was significantly associated with an increased 67-gallium uptake and late inspiratory crackles (P < 0.01), and to a lesser extent with an abnormal interstitial pattern in CT (P < 0.055). Parameters of lung function and laboratory parameters were related to alveolitis using multivariate testing. Considering the alveolitis subtype (granulo- or lymphocytosis), only a reduced FEV1 showed a relationship to granulocytic alveolitis (P < 0.01). Late inspiratory crackles and increased 67 gallium uptake as non-invasive diagnostic findings point out alveolitis in CTD remarkably. Therapeutic and prognostic aspects necessitate BAL to specify the type of alveolitis (lymphocytosis or granulocytosis or mixed forms) in CTD patients with lung manifestation. Non-invasive diagnostic procedures cannot predict the type of alveolitis sufficiently.

Adult↗
PubMed1996

[Interventional pneumology: procedures for pulmonary hemorrhage and tumor-induced superior vena cava syndrome].

Interventional pneumology includes both bronchological and vascular methods of diagnostic and therapy, especially in case of pneumological emergency, such as pulmonary hemorrhage and superior vena cava syndrome. In massive pulmonary hemorrhage bronchological diagnosis is needed to determine the location and activity of the bleeding, as well as angiography of bronchial arteries, and of pulmonary arteries, respectively. Bronchus occlusion by aid of balloon catheter or double lumen tube are intermediate methods to bridge over till defenitive surgery or embolisation of bronchial or pulmonal arteries as complementary methods in patients with pulmonary hemorrhage. In patients suffering from superior vena cava syndrome caused by neoplasms venous angioplasty and Wallstent implantation provide immediate clinical improvement.

Angioplasty, Balloon↗
PubMed1996

[Percutaneous "high risk" angioplasty with prophylactic cardiopulmonary support. High risk PTCA with mechanical circulatory support].

With improved technology and development of several mechanical assist devices, the indications of percutaneous transluminal coronary revascularization have been extended. In 39 patients (30 men, mean age = 60.1 +/- 8.1 years) with angina pectoris or heart failure, with poor operative risk-benefit ratio and ejection fraction < 35% and/or target vessel supplying > 50% of the viable myocardium, we performed assisted percutaneous transluminal coronary revascularization. Intraortic balloon counterpulsation (n = 16), extracorporal circulation (n = 21), or hemopump (n = 2) were used for mechanical support. Complete 6-week follow up was possible in 27 patients. An improvement of left-ventricular function (patients with EF < or = 35% demonstrated an improvement: 27 +/- 7 vs 36 +/- 10%, p < 0.05), heart failure (patients with EF < or = 35% demonstrated an improvement of maximal oxygen uptake: 14 +/- 4 vs 17 +/- 4 ml/kg/min; p < 0.05) and a marked improvement of angina (23/38 demonstrated CCS-improvement of at least one class) was found. Hospital mortality was as low as 2.6%. Major postinterventional complications included nonfatal myocardial infarction (n = 2), fatal retroperitoneal bleeding (n = 1), pulmonary edema (n = 1), nonfatal ventricular fibrillation (n = 1), cerebrovascular event without residual (n = 1), and deep vein thrombosis (n = 4). In conclusion, assisted percutaneous revascularization was successful in a high risk subset of patients with increased surgical risk and/or poor ventricular function.

Aged↗
PubMed1996

Doppler-derived diastolic indices in dilated cardiomyopathy: a hemodynamic evaluation relating pre- and afterload parameters to flow velocity.

OBJECTIVE: To explain the well known finding of a normal early diastolic filling velocity in advanced grade heart failure due to dilated cardiomyopathy (DCM) exclusively by hemodynamics and to relate Doppler-flow velocity parameters to indices representing pre- and afterload. DESIGN: DCM was hypothesized to be a disorder in which pre- and afterload contribute in equal proportion to cardiac insufficiency independently from ischemic impairment of relaxation. PATIENTS: Twenty patients with DCM were enroled in the study after definitive exclusion of coronary and valvular heart disease. METHODS: Diastolic transmitral and transtricuspid Doppler readings and hemodynamic measurements were done simultaneously by two blinded observers. A Swan-Ganz catheter was employed. MAIN RESULTS: Simple and multiple regression analyses revealed early diastolic filling velocity to depend on hemodynamic parameters representing afterload. Pulmonary capillary wedge pressure (PCWP) was found to be directly related to early diastolic filling velocity. An inverse relation between early diastolic filling velocity and parameters representing afterload (systemic vascular resistance and mean arterial pressure) was demonstrated; however the most significant correlation using multiple regression analysis was shown between mitral early diastolic peak-flow velocity (dependent) and PCWP as well as systemic vascular resistance index (independents) (r = 0.75; P < 0.001). Correspondingly, the transtricuspid early diastolic peak-flow velocity was shown to be related to the equilibrium of right atrial pressure and pulmonary vascular resistance index. The atrial diastolic flow velocity parameters were found not to be related to hemodynamic indices. CONCLUSION: A definitive but not one-to-one relationship between early diastolic Doppler-flow indices and hemodynamic parameters was defined. A functional coupling of pre- and afterload can be considered the main determinant of early diastolic filling velocity in DCM.

Adult↗
PubMed1995

Dynamic three-dimensional transesophageal echocardiography using a computed tomographic imaging probe--clinical potential and limitation.

Dynamic three-dimensional echocardiography is a new diagnostic tool for spatial visualisation of cardiac anatomy and volumetric assessment. A computer-controlled probe acquires parallel tomographic slices, from which dynamic three-dimensional images of the heart can be reconstructed. Thirty adult patients with valvular heart diseases, congenital heart diseases, intracardiac masses, heart failure and other cardiac lesions, underwent conventional two-dimensional (n = 30), three-dimensional echocardiography (n = 30) and thermodilution (n = 17). The feasibility, usefulness and possibility of simulating a surgical view of intracardiac anatomy and exact volumetry were determined. The two different morphologic images were compared qualitatively. For quantitative analysis volumetry was performed using standard thermodilution technique and dynamic three-dimensional echocardiography. In more than 80% of the patients additional morphologic information was gained and a strong correlation (r = 0.75-0.95) between two volumetry assessments was found. Based on this findings, dynamic three-dimensional echocardiography is an additional and valuable approach in the perioperative and intensive care management in this group of patients.

Adult↗
PubMed1995

Heterogeneity of left ventricular regional wall thickening following dobutamine infusion in normal human subjects.

BACKGROUND: Pathophysiological data and pragmatic clinical experience with stress echocardiography suggest that inotropic stimulation with simultaneous changes in heart rate and loading conditions can affect the function of various myocardial regions asymmetrically, inducing heterogeneity in wall motion and thickening, possibly mimicking 'ischaemic' regional hypokinesis or lack of hyperkinesis during stress. OBJECTIVES: To describe, in a quantitative fashion, the physiological contractile response of different left ventricular regions following dobutamine infusion. METHODS: Two hundred and twenty-three in-hospital patients undergoing dobutamine stress echocardiography and coronary angiography were initially considered. Of these 223 patients, 18 had angiographically normal coronary arteries, normal resting function, negative ergonovine and exercise stress tests, and negative dobutamine stress echocardiograms; of the 18, only in 11 patients (six females, age = 56 +/- 10 years) was it possible to obtain quantitative measurements of the middle segments of the inferior, anterior, lateral, and septal walls. Two-dimensional echocardiographic measurements of wall thickness were obtained at the end-diastolic (onset of Q wave) and end-systolic phases, both at baseline (rest) and at the peak of the dobutamine infusion (40 micrograms.min-1.kg-1 plus atropine). RESULTS: Dobutamine increased heart rate (rest = 69 +/- 9 vs dobutamine = 138 +/- 13 beats.min-1; P < 0.01), whereas systolic blood pressure did not change significantly (rest = 136 +/- 15 vs dobutamine = 150 +/- 25 mmHg, P = ns). During stress, % systolic thickening decreased in the inferior wall (rest = 73 +/- 24 vs dobutamine +/- 50 +/- 9%; P < 0.01), whereas it tended to increase to a variable extent in the other regions, i.e. septal (rest = 46 +/- 17 vs dobutamine = 68 +/- 13%, P < 0.01), anterior (rest 62 +/- 19 vs dobutamine = 69 +/- 11%, P = ns), and lateral wall (rest = 48 +/- 16 vs dobutamine = 61 +/- 18%, P = ns). The decrease in % systolic thickening of the inferior wall was inversely correlated with the increase in end-diastolic wall thickness (r = -0.75; P < 0.01), but neither with heart rate (r = 0.15; P = ns) nor with systolic blood pressure changes (r = 0.05; P = ns). CONCLUSIONS: Heterogeneity of left ventricular wall thickening can be induced or magnified by dobutamine infusion even in subjects without coronary artery disease, with the inferior wall showing a lack of hyperkinesis, up to relative hypokinesis, in comparison with other myocardial regions. Caution in aggressive dobutamine stress echocardiography reading, especially in the inferior wall, might be warranted.

Adult↗
PubMed1994

Cloning and characterization of the gene for the catalytic subunit of cAMP-dependent protein kinase in the aquatic fungus Blastocladiella emersonii.

We have isolated and characterized cDNA and genomic DNA clones encoding the catalytic subunit (C) of cAMP-dependent protein kinase in the aquatic fungus Blastocladiella emersonii. The C-subunit amino acid sequence derived from the nucleotide sequence predicts a basic polypeptide of 424 residues, excluding the initiator methionine, which by amino-terminal sequence analysis has been shown to be absent from the mature protein. The Blastocladiella C presents a 70-amino-acid extension at the amino terminus, when aligned to the mouse C alpha subunit, being one of the largest C subunits already characterized. The B. emersonii C-gene-coding region is interrupted by three introns, ranging in size over 57-69 bp. The positions of the introns are quite different from those found in other species, suggesting a considerable amount of evolutionary drift in the gene structure. The 5'-flanking region lacks recognizable TATA or CCAAT sequences, is remarkably high in GC content (70%), and primer extension experiments indicate that transcription initiates from multiple sites. Several sequence motifs were identified in the promoter region which could be involved in the developmental control of this gene.

Amino Acid Sequence↗
PubMed1994

Left and right heart Doppler stress echo in congestive heart failure.

Doppler echocardiographic assessment of the left and right ventricular function at rest, during and 6 minutes after submaximal exercise was performed in 60 patients with a mean age of 43 +/- 11 years suffering from heart failure classified stage I-III according to the NYHA-criteria and 10 volunteers with a mean age of 36 +/- 9 years who served as a control group. At mitral (m) and tricuspid (t) valve early diastolic peak-flow velocity (VEm, VEt), atrial peak-flow velocity (VAm, VAt), speed-time integrals (Em, Et, Am, At) and the ratios (VE/VAm, VE/VAt, E/Am, E/At) were determined. The left ventricular end-diastolic diameter (LVEDD) and the right ventricular outflow tract (RVOT) were measured in addition. The left ventricular ejection fraction (LVEF) was decreased to < 36% in 9 patients (group 1). In 51 individuals LVEF was found to be > 35% but < 50% or LVEF was shown to be > 50% but VE/VAm-ratio was found to be < 1 (group 2). Out of all the determined parameters, VE/VAt, VEt and VAm during exercise were found to be the most sensitive parameters for the detection of early to advanced grade left heart failure.

Adult↗
PubMed1993

[Pathophysiology of gallstone formation].

There are two types of gallstones: cholesterol and pigment stones. The pathogenesis is divided into three phases: supersaturation, nucleation and stone growth. Hypersecretion of biliary cholesterol, crystallization promoting and inhibiting factors, gallbladder hypomotility, arachidonyl lecithin, prostaglandins, mucin and calcium play an important role in the formation of gallstones. For the formation of pigment stones a decreased secretion of biliary acids, an increased secretion of unconjugated bilirubin into the bile and an infection of the biliary tract are the most important causative factors.

Bile Acids and Salts↗
PubMed1993

Doppler stress echocardiography of the left and right ventricle: a new echo device to quantify left ventricular backward failure.

OBJECTIVES: A novel non-invasive procedure which evaluates left-right ventricular interaction is introduced. This procedure is suitable for the classification of congestive heart failure. METHODS: In 48 patients showing mild, moderate or advanced stage congestive heart failure (NYHA I-III) Doppler echocardiography was performed at rest, during and after submaximal bicycle exercise. Mitral (m) and tricuspid (t) filling parameters were determined: early diastolic (VEm, VEt) and atrial maximal velocities (VAm, VAt), the velocity integrals (Em, Et, Am, At) and the corresponding ratios (VE/VAm, VE/VAt, E/Am, E/At). Group 1 (n = 29) was composed of those patients presenting with a VE/VAm < 1 at rest. Four individuals (group 2) were found to have a VE/VAm ratio < 1 during exercise only. Six other patients showing a dilated left ventricle or an ejection fraction of less than 40% produced false negative results in left ventricular Doppler examination (VE/VAm > 1) at rest and during exercise (group 3). In 9 cases (group 4) systolic function, size and Doppler echocardiographic parameters of the left ventricle were proven to be normal. RESULTS: The VE/VAt-ratio decreased notably during exercise (p < 0.05) but increased again after exercise in group 3. In the groups 1 and 2 similar changes occurred as well, however not to a significant degree. In group 4, exercise VE/VAt ratio did not differ from values seen at rest or during recovery (variability 4%). CONCLUSION: The results of this study indicate, that high sensitivity towards left ventricular backward failure can be achieved for Doppler stress echocardiography by extending the examination to right-sided diastolic parameters.

Adolescent↗