Biomedical subjects

B C Maciel

Publications and source records attributed to B C Maciel.

62 records · Page 4Linked to original sources

PubMedDate not supplied

Functional pulmonary atresia in a newborn with normal intracardiac anatomy.

Functional pulmonary atresia is a relatively rare clinical condition usually associated with Ebstein's malformation, tricuspid valve dysplasia, Uhl's anomaly, or transient myocardial ischemia with severe tricuspid regurgitation. The occurrence of functional pulmonary atresia associated with transient tricuspid regurgitation in a newborn with an anatomically normal heart is even more uncommon. We describe a case in which color Doppler flow mapping played an essential role in diagnosis and follow-up of this clinical condition in a newborn who had normal intracardiac anatomy.

Diagnosis, Differential↗

PubMedDate not supplied

Color flow Doppler mapping studies of "physiologic" pulmonary and tricuspid regurgitation: evidence for true regurgitation as opposed to a valve closing volume.

Color flow Doppler mapping using either an Aloka 880 or a Toshiba SSH65A system was performed in 39 normal subjects (aged 13 to 45 years) and 43 patients (aged 13 to 82 years) with pathologic tricuspid or pulmonary regurgitation to evaluate the incidence of "physiologic" regurgitation of right heart valves and to determine the differentiating characteristics in the spatial distribution and velocity encoding of "normal" and "pathologic" regurgitant jets. In the normal subjects, tricuspid and pulmonary regurgitation were documented in 32 (83%) and 36 (93%), respectively, and were unrelated to the system being used. Flow acceleration and aliasing were imaged on the right ventricular side of the tricuspid regurgitant orifice and on the pulmonary artery side of the pulmonary valve (in both normal subjects and patients), and indicated flow convergence for true regurgitation through an orifice as opposed to blood being driven retrogradely by the closing valve. Such proximal acceleration was documented in all patients with pathologic tricuspid regurgitation, in 31/32 of the normal subjects with tricuspid regurgitation, and was also observed in 12/15 (80%) of the patients and 4/12 (33%) of normal subjects with pulmonary regurgitation who were examined with the Toshiba system. The dimensions (mean +/- SD) of tricuspid regurgitant jets (length [JL] and area [JA]) were consistently larger in the patients than in the normal subjects [JL: 3.4 +/- 0.9 vs 1.2 +/- 0.5 cm, p less than 0.001; and JA: 5.7 +/- 2.0 vs 1.4 +/- 0.7 cm2, p less than 0.001) as were the pulmonary regurgitation jet dimensions (JL: 1.8 +/- 0.4 vs 0.9 +/- 0.08 cm, p less than 0.001; JA: 1.8 +/- 0.7 vs 0.3 +/- 0.08 cm2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Cardiac tamponade: an unusual complication of pericardial cyst.

Pericardial cysts are not common and rarely cause symptoms. We report a unique case of a 15-year-old male patient with cardiac tamponade clinically diagnosed who was referred for echocardiography. Transthoracic echocardiography revealed, in addition to a large pericardial effusion associated with echocardiographic signs of cardiac tamponade, an 8 x 5 cm echofree image suggesting a pericardial cyst adjacent to the right atrium. Immediately after pericardiocentesis, yielding a serosanguinous liquid, the patient showed striking clinical improvement and echocardiography demonstrated minimal pericardial effusion with persistence of the cystic image. At surgery a pericardial cyst containing a sanguinous fluid was found and the pathologic findings were consistent with hematic pericardial cyst. Thus echocardiography played a fundamental role for the diagnosis and treatment of the rare complication of a pericardial cyst documented in this patient.

Adolescent↗

PubMedDate not supplied

Ventricular function in Chagas' heart disease.

Invasive and noninvasive methods used to evaluate ventricular function in Chagas's disease are reviewed. The traditional indices of overall ventricular performance reflect the interaction of preload, contractility, afterload and heart rate. Therefore, they are unable to distinguish changes in contractility from modifications of loading conditions. The role of ventricular function as a predictor of mortality in chronic Chagas' heart disease is discussed. Ventricular function abnormalities in patients with indeterminate and digestive forms of Chagas' disease are especially emphasized. Finally, the evidence of early impairment of diastolic performance in digestive forms of Chagas' disease are especially emphasized. Finally, the evidence of early impairment of diastolic performance in patients with Chagas' disease is presented.

Chagas Cardiomyopathy↗

PubMedDate not supplied

Studies of the coronary circulation in Chagas' heart disease.

Pathogenesis of chronic Chagas' heart disease may include various disturbances in the coronary circulation, that could be responsible for the myocardial lesions seen in human hearts and in experimental models of the disease. In this paper we critically reviewed the anatomical and functional abnormalities described in chronic chagasic patients, pertaining to the so-called vascular pathogenetic theory of Chagas' disease. The epicardial coronary arteries are usually free of significant obstructive disease in nonselected groups of chagasic patients examined at autopsy or by coronary angiography. However, chagasic patients who were studied after an episode of acute myocardial infarction, show the same patterns of atherosclerotic coronary artery disease seen in the general nonchagasic population. Studies of chagasic patients with angiographically normal coronary arteries, by several scintigraphy methods, revealed myocardial perfusion abnormalities which may be caused by the microcirculatory derangements described in animals experimentally infected with the T. cruzi. Since hypoperfusion has been detected in regions with normal or mildly impaired wall motion, it is likely that the microvascular disturbances precede and may be causative mechanism for the subsequent myocardial damage. We speculate that hibernating ventricular areas may occur in chagasic patients, on the basis of the evidence gathered from these studies. Recent investigations of chronic patients with Chagas' disease and chest pain showed attenuation of the vasomotor responses to physiological and pharmacological stimuli, in the epicardial coronary arteries.

Animals↗

PubMedDate not supplied

[Transesophageal atrial stimulation].

Considering that catheterization of the esophagus is a relatively easy procedure, we studied the electrical transesophageal atrial stimulation in ninety patients (age range 15 to 75 years (mean 42 +/- 9 years). A multipolar electrode catheter was introduced through the nose into the esophagus of each patient and fixed in position at a site where the simultaneous recording of intraesophageal unipolar electrocardiographic derivations showed the greatest P wave potentials. Electrical atrial capture through the esophagus was obtained at frequency values higher than that of the heart, with lower voltages needed for atrial stimulation at the site in which the unipolar recording of the intraesophageal P wave was of highest amplitude. The difference of potential used was between 6 and 30 volts, with the highest values corresponding to patients with megaesophagus, whereas values below 15 volts were tolerated without major discomfort. Electric pulses of more than 10 ms duration did not significantly reduce the intensity of electric current needed to produce the atrial command. The stimulation bipole (area to be stimulated per pole, 0.72 cm2) had an interpolar distance of 22 or 30 mm, our overall experience showing that distances up to 44 mm did not require higher voltages. No cases of esophageal damage or severe arrhythmia were reported due to stimulation. In the present study, programmed transesophageal stimulation proved to be a good option for the evaluation of sinus node function and for the study and reversal of paroxysmal supraventricular tachycardia attacks by a reentry mechanism, representing in some cases an alternative approach for the study of atrioventricular conduction.

Adolescent↗

PubMedDate not supplied

Radionuclide angiographic evidence for early predominant right ventricular involvement in patients with Chagas' disease.

Radionuclide angiography was used to study biventricular function in 11 noncardiac (group 1) and eight chronic cardiac chagasic patients (group 2). Results in chagasic patients were compared to those obtained in 10 normal subjects. Global ejection fraction and the standard deviation of peak (SDP) phase histogram were determined for each ventricle and qualitative evaluation of regional wall motion in both anterior and left anterior oblique projections was performed. Left ventricular dysfunction was markedly predominant in group 2, mean +/- SD ejection fraction 39.7 +/- 13.1% and SDP 29.8 +/- 15.6 degrees, as compared to group 1, in which these values were 56.7 +/- 9.9% (P less than 0.01) and 18.3 +/- 7.1 degrees (P less than 0.05), respectively. In contrast, severe right ventricular impairment was found equally in both groups: ejection fraction averaged 31.8 +/- 12.7 and 31.0 +/- 9.1%, and the mean SDP was 29.3 +/- 8.6 and 23.7 +/- 6.7 degrees, in groups 2 and 1, respectively. The qualitative analysis of segmental wall motion also showed apical and/or free-wall right dysynergy in all patients of group 1, while the same abnormalities were detected in six out of eight patients in group 2. These findings indicate that severe functional impairment of right ventricular performance is by far the most significant abnormality detected by radionuclide angiography in chagasic patients who are asymptomatic and have no other clinical sign of heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Control of heart rate during exercise in health and disease.

The authors present a review of their contributions over the last decade to the study of the autonomic control of heart rate during dynamic exercise under physiological and pathological conditions. These studies included the development of new methods for the evaluation of autonomic control of heart rate during dynamic exercise in man. Pharmacological blockade of sympathetic (propranolol) and parasympathetic (atropine) efferent nerves was used to demonstrate differences in time constants and power-dependent relative participation of each division of the autonomic nervous system, as predominant mechanisms responsible for the tachycardia occurring during dynamic exercise. These findings have permitted the use of properly standardized dynamic exercise (discontinuous protocol: step powers, seated position on a bicycle ergometer, 4-min duration), as a simple and noninvasive test for the evaluation of autonomic control of the sinus node. This test has proved to be useful for detecting physiological autonomic adaptations induced by aerobic training, as well as dysfunctions occurring in pathologic conditions such as Chagas' disease and hyperthyroidism.

Atropine↗