Mechanical Properties and Morphology of Multifunctional Polypropylene Foams

One of the actual trends in polymer foams consists in the development of new materials by combining density reduction through foaming with the incorporation of functional fillers. This would enable to obtain materials with improved specific properties and added functionalities. There is also a growing interest in the use of environmentally-friendly materials obtained from renewable sources, thus coming as a logical step to combine both in order to create novel biocomposite foams. This work presents an overview of our recent results regarding the preparation and structural and thermo-mechanical characterizations of rigid polypropylene-based composite foams, with the main goal of developing new lightweight materials with tailor-made properties (multifunctional foams). Several reinforcements have been considered, from renewable cellulose fibres to nanometric-sized reinforcements such as silicate-layered nanoclays and carbon nanofibres.

Noise detection during heart sound recording using periodicity signatures

Heart sound is a valuable biosignal for diagnosis of a large set of cardiac diseases. Ambient and physiological noise interference is one of the most usual and highly probable incidents during heart sound acquisition. It tends to change the morphological characteristics of heart sound that may carry important information for heart disease diagnosis. In this paper, we propose a new method applicable in real time to detect ambient and internal body noises manifested in heart sound during acquisition. The algorithm is developed on the basis of the periodic nature of heart sounds and physiologically inspired criteria. A small segment of uncontaminated heart sound exhibiting periodicity in time as well as in the time-frequency domain is first detected and applied as a reference signal in discriminating noise from the sound. The proposed technique has been tested with a database of heart sounds collected from 71 subjects with several types of heart disease inducing several noises during recording. The achieved average sensitivity and specificity are 95.88% and 97.56%, respectively.

Beat-to-beat cardiac output inference using heart sounds

Cardiac output (CO) change is the primary compensatory mechanism that responds to oxygenation demand. Its continuous monitoring has great potential for the diagnosis and management of cardiovascular diseases, both in hospital as well as in ambulatory settings. However, CO measurements are currently limited to hospital settings only. In this paper, we present an extension of the model proposed by Finkelstein for beat-to-beat CO assessment. We use a nonlinear model consisting of a two-layer feed-forward artificial neural network. In addition to demographic (body surface area and age) and physiological parameters (HR), surrogates of contractility, afterload and mean arterial pressure based on systolic time intervals (STIs), estimated from echocardiography and heart sounds are used as inputs to our models. The results showed that the proposed models--with echocardiography as reference--produce better estimations of stroke volume/CO than the Finkelstein model (12.83 ± 10.66 ml vs 7.23 ± 6.6 ml), as well as higher correlation (0.46 vs 0.82).

Characterization of highly oriented organoclay/ poly(methyl methacrylate) moulded nanocomposites

In the present paper, the effects of nanoparticles' content and orientation were studied on the structure, phase morphology and thermo-mechanical properties of highly oriented montmorillonite/ poly(methyl methacrylate) moulded nanocomposites. The nanocomposites were compounded using a co-rotating high-shear twin-screw extruder. Square plates were prepared by a two-stage compression-moulding process from the previously extruded materials, with the test specimens being directly machined in both parallel and perpendicular directions with respect to the plate's surface. Wide-angle X-ray diffraction (WAXD) revealed a highly-ordered structure of silicate platelets parallel to the plate's surface. Observations by transmission electron microscopy (TEM) supported this analysis, demonstrating the high anisotropy degree of the nanocomposites. Dynamic mechanical thermal analysis (DMTA) showed that the perpendicular specimens were stiffer than the parallel ones, with the presence of the oriented nanoparticles decreasing PMMA's mobility during the glass transition, although no significant differences were registered in the T(g) temperatures with increasing the amount of clay content or with orientation. Remarkable improvements regarding the fracture energy were observed for the perpendicular specimens, with the 20 wt% oMMT nanocomposite showing a fracture energy almost 10 times that of pure PMMA.

Characterization of carbon nanofibre-reinforced polypropylene foams

In this paper, carbon-nanofibre-reinforced polypropylene foams were prepared and characterized regarding their foaming behaviour, cellular structure and both thermo-mechanical as well as electrical properties. Polypropylene (PP) nanocomposites containing 5, 10 and 20 wt% of carbon nanofibres (CNF) and a chemical blowing agent were prepared by melt-mixing inside a twin-screw extruder and subsequently water-cooled and pelletized. The extruded nanocomposites were later foamed using a one-step compression-moulding process. The thermo-mechanical properties of the CNF-reinforced PP foams were studied, analyzing the influence of the carbon nanofibres on the cellular structure and subsequent thermo-mechanical behaviour of the foams. Carbon nanofibres not only seemed to act as nucleating agents, reducing the average cell size of the foams and increasing their cell density for similar expansion ratios, but also helped produce mechanically-improved foams, even reaching for the 20 wt% CNF-reinforced ones a specific modulus around 1.2 GPa x cm3/g for densities as low as 300 kg/m3. An increasingly higher electrical conductivity was assessed for both the solids as well as the foams with increasing the amount of carbon nanofibres.

Heart murmur classification with feature selection

Heart sounds entail crucial heart function information. In conditions of heart abnormalities, such as valve dysfunctions and rapid blood flow, additional sounds are heard in regular heart sounds, which can be employed in pathology diagnosis. These additional sounds, or so-called murmurs, show different characteristics with respect to cardiovascular heart diseases, namely heart valve disorders. In this paper, we present a method of heart murmur classification composed by three basic steps: feature extraction, feature selection, and classification using a nonlinear classifier. A new set of 17 features extracted in the time, frequency and in the state space domain is suggested. The features applied for murmur classification are selected using the floating sequential forward method (SFFS). Using this approach, the original set of 17 features is reduced to 10 features. The classification results achieved using the proposed method are compared on a common database with the classification results obtained using the feature sets proposed in two well-known state of the art methods for murmur classification. The achieved results suggest that the proposed method achieves slightly better results using a smaller feature set.

Comparison of systolic time interval measurement modalities for portable devices

Systolic time intervals (STI) have shown significant diagnostic and prognostic value to assess the global cardiac function. Their value has been largely established in hospital settings. Currently, STI are considered a promising tool for long-term patient follow-up with chronic cardiovascular diseases. Several technologies exist that enable beat-by-beat assessment of STI in personal health application scenarios. A comparative study is presented using the echocardiographic gold standard synchronized with impedance cardiography (ICG), phonocardiography (PCG) and photoplethysmography (PPG). The ability of these competing technologies in assessing the pre ejection period (PEP) and the left ventricle ejection time (LVET) is given a general overview with comparative results.

Noise detection during heart sound recording

Heart sound is a valuable biosignal for early detection of a large set of cardiac diseases. Ambient and physiological noise interference is one of the most usual and high probable incidents during heart sound acquisition. It may change the prominent and crucial characteristics of heart sound which may possess important information for heart disease diagnosis. In this paper, we propose a new method to detect ambient and internal body noises in heart sounds. The algorithm utilizes physiologically inspired periodicity/semi-periodicity criteria. A small segment of clean heart sound exhibiting periodicity in the time and in the frequency domain is first detected. The sound segment is used as a template to detect uncontaminated heart sounds during recording. The technique has been tested on the heart sounds contaminated with several types of noises, recorded from 68 different subjects. Average sensitivity of 95.13% and specificity of 98.65% for non-cardiac sound detection were achieved.

Heart murmur recognition and segmentation by complexity signatures

Heart sound analysis has been a topic of investigation for several years. Since heart sounds directly encode the mechanical activity of the heart, they enable the assessment and follow-up of several types of heart disorders in pre-symptomatic states. Murmurs are the most common abnormality signature in many heart disorders. This paper introduces an algorithm for heart murmur identification. In the presence of murmurs, heart sounds exhibit chaotic behavior. In the proposed method this is assessed based upon the nonlinear dynamics of the signal. In order to segment murmurs from other heart sound components, the signal is transformed into a phase space that is later reconstructed using the embedded matrix. Based on the phase space, the complexity and the strength of the signal are computed. These features are the basis for sound component boundary location. The method has been tested with a database of heart sounds that include diverse heart lesions and heart murmurs. The algorithms achieved 91.09% sensitivity and 95.25% specificity.

Assessing systolic time-intervals from heart sound: a feasibility study

Systolic time intervals are highly correlated to fundamental cardiac functions. In this paper we investigate the feasibility of using heart sound (HS) to accurately measure the opening and closing moments of the aortic valve, since these are crucial moments to define the main systolic timings of the heart cycle, i.e. the pre-ejection period (PEP) and the left ventricular ejection time (LVET). We introduce a HS model, which is applied to define several features that provide clear markers to identify these moments in the HS. Using these features and a comparative analysis with registered echocardiographies from 17 subjects, the results achieved in this study suggest that HS can be used to accurately estimate LVET and PEP.

Assessing PEP and LVET from heart sounds: algorithms and evaluation

This paper addresses the estimation of systolic time intervals, namely the pre-ejection period (PEP) and the left ventricular ejection time (LVET), using heart sound. PEP is estimated with a Bayesian approach resorting to the signal's instantaneous amplitude and typical time intervals between atrio-ventricular valve closure and aortic valve opening. As for LVET, aortic valve closure is determined through the analysis of a high-frequency signature of S2. Additionally, LVET has also been estimated from a PPG signal at a peripheral site, for the sake of comparison over a subset of data. We evaluated our algorithms on a set of 658 heartbeats and achieved 10.32 msec average absolute PEP estimation error with 7.3 msec standard deviation and for LVET, 15.8 msec average estimation error with 13.6 msec standard deviation. Current results support our assumption that heart sounds can be applied to detect the onset of the aortic valve movement processes.

Bayesian classification and non-Bayesian label estimation via EM algorithm to identify differentially expressed genes: a comparative study

Gene classification problem is studied considering the ratio of gene expression levels, X, in two-channel microarrays and a non-observed categorical variable indicating how differentially expressed the gene is: non differentially expressed, down-regulated or up-regulated. Supposing X from a mixture of Gamma distributions, two methods are proposed and results are compared. The first method is based on an hierarchical Bayesian model. The conditional predictive probability of a gene to belong to each group is calculated and the gene is assigned to the group for which this conditional probability is higher. The second method uses EM algorithm to estimate the most likely group label for each gene, that is, to assign the gene to the group which contains it with the higher estimated probability.

Ventricular arrhythmias assessment

An integrated framework for ventricular arrhythmias (VA) assessment, composed of two levels, is proposed in this work. The first level consists of four independent neural networks (NN), designed for specific detection tasks: signal quality, premature ventricular contractions (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF). Time and frequency domain features, obtained from the electrocardiogram (ECG) and selected through a correlation analysis procedure, form the inputs to the neural modules. The outputs feed the second layer, which consists of a global classifier (ANFIS structure), returns the global result for the VA assessment scheme. Sensitivity and specificity values, evaluated from public MIT-BIH databases, show the effectiveness of the proposed strategy.

Detection of S1 and S2 heart sounds by high frequency signatures

A new unsupervised and low complexity method for detection of S1 and S2 components of heart sound without the ECG reference is described The most reliable and invariant feature applied in current state-of-the-art of unsupervised heart sound segmentation algorithms is implicitly or explicitly the S1-S2 interval regularity. However; this criterion is inherently prone to noise influence and does not appropriately tackle the heart sound segmentation of arrhythmic cases. A solution based upon a high frequency marker; which is extracted from heart sound using the fast wavelet decomposition, is proposed in order to estimate instantaneous heart rate. This marker is physiologically motivated by the accentuated pressure differences found across heart valves, both in native and prosthetic valves, which leads to distinct high frequency signatures of the valve closing sounds. The algorithm has been validated with heart sound samples collected from patients with mechanical and bio prosthetic heart valve implants in different locations, as well as with patients with native valves. This approach exhibits high sensitivity and specificity without being dependent on the valve type nor their implant position. Further more, it exhibits invariance with respect to normal sinus rhythm (NSR) arrhythmias and sound recording location.

Third heart sound detection using wavelet transform-simplicity filter

Heart failure and heart valvar diseases are chronic heart disorders which are potentially diagnosed using heart sound characteristics. Heart sound components S1 and S2 exhibit significant characteristics for valvar dysfunction while pathological S3 sound is a prominent sign for heart failure in elderly people. In this paper, a new automatic detection method of the S3 heart sound is proposed. The method is build upon wavelet transform-simplicity filter which separates S1, S2 and S3 sounds from background noise enabling heart sound segmentation even in the presence of heart murmurs or noise sources. The algorithm uses physiologically inspired criteria to assess the presence of S3 heart sound components and to perform their segmentation. Heart sound samples recorded from children as well as from elderly patients with heart failure were used to test the method. The achieved sensitivity and specificity were 90.35% and 92.35%, respectively.

On the detection of Premature Ventricular Contractions

Premature Ventricular Contractions (PVC) are a cardiac arrhythmia that can be associated with an increased risk of adverse cardiac events such as ventricular arrhythmias and sudden death. Therefore, the characterization of this arrhythmia becomes crucial in the early diagnosis and prevention of possible life threatening cardiac diseases. In this paper a new approach for automatic detection of PVCs is presented, based on morphological derivatives and information theory techniques. Using these approaches a set of patient invariant features is introduced. Sensibility and specificity results (respectively, 96.35% and 99.15%) show the potential of the algorithm when applied to the MIT-BIH Arrhythmia database.

Phase space reconstruction approach for ventricular arrhythmias characterization

Ventricular arrhythmias, especially tachycardia and fibrillation are one of the main causes of sudden cardiac death. Therefore, the development of methodologies, enable to detect their occurrence and to characterize their time evolution, is of fundamental importance. This work proposes a non-linear dynamic signal processing approach to address the problem. Based on the phase space reconstruction of the electrocardiogram (ECG), some features are extracted for each ECG time window. Features from current and previous time windows are provided to a dynamic neural network classifier, enabling arrhythmias detection and evolution trends assessment. Sensitivity and specificity values, evaluated from public MIT-BIH databases, show the effectiveness of the proposed strategy.

Neutrophil oxidative metabolism in diabetic patients undergoing pancreas transplantation

A pancreas transplantation is the only therapy capable of returning a constant, physiological euglycemic state to diabetic patients. Considering the clinical controversies in the study of infection in diabetes and the recognized effect of insulin on the oxidative metabolism of glucose in phagocytes, the present study sought to evaluate the formation of intraphagocytic oxygen-free radicals in diabetic patients undergoing simultaneous pancreas kidney transplantation (SPK).

METHODS

Twenty-five diabetic patients undergoing SPK were compared with 25 normal individuals. Evaluation of the oxidative metabolism of leukocytes was performed using the NBT test.

RESULTS

The abnormality in the pretransplant counts (19.32%-28.2%) reached normal levels at 48 hours after transplantation (45.11%-76.25%) and was maintained to the 5th day (46.28%-76.20%).

CONCLUSION

An SPK in a diabetic patient normalized the formation of intraphagocytic oxygen-free radicals.

Contribution for new genetic markers of rheumatoid arthritis activity and severity: sequencing of the tumor necrosis factor-alpha gene promoter

The objective of this study was to assess whether clinical measures of rheumatoid arthritis activity and severity were influenced by tumor necrosis factor-alpha (TNF-alpha) promoter genotype/haplotype markers. Each patient's disease activity was assessed by the disease activity score using 28 joint counts (DAS28) and functional capacity by the Health Assessment Questionnaire (HAQ) score. Systemic manifestations, radiological damage evaluated by the Sharp/van der Heijde (SvdH) score, disease-modifying anti-rheumatic drug use, joint surgeries, and work disability were also assessed. The promoter region of the TNF-alpha gene, between nucleotides -1,318 and +49, was sequenced using an automated platform. Five hundred fifty-four patients were evaluated and genotyped for 10 single-nucleotide polymorphism (SNP) markers, but 5 of these markers were excluded due to failure to fall within Hardy-Weinberg equilibrium or to monomorphism. Patients with more than 10 years of disease duration (DD) presented significant associations between the -857 SNP and systemic manifestations, as well as joint surgeries. Associations were also found between the -308 SNP and work disability in patients with more than 2 years of DD and radiological damage in patients with less than 10 years of DD. A borderline effect was found between the -238 SNP and HAQ score and radiological damage in patients with 2 to 10 years of DD. An association was also found between haplotypes and the SvdH score for those with more than 10 years of DD. An association was found between some TNF-alpha promoter SNPs and systemic manifestations, radiological progression, HAQ score, work disability, and joint surgeries, particularly in some classes of DD and between haplotypes and radiological progression for those with more than 10 years of DD.

ECG Compression through segment matching and progressive error encoding

This work describes a lossy Electrocardiogram (ECG) compression algorithm based on R-R segmentation and segment matching. An ECG can be thought of as a quasi-periodic signal, with many similarities existing between heartbeats acquired from the same source. Through the use of an adaptive dictionary, it is possible to explore the similarities between new and previously encountered patterns, incorporating new patterns when a significant change in morphology has been observed. Algorithm simulation reveals very high compression ratios are possible on very regular signals.

Pancreatic Islet Cells Antibodies in Diabetic Patients Submitted to Pancreas Transplantation

Several pieces of evidence suggest an autoimmune etiology of diabetes mellitus type 1. To trace patients who are susceptible to the disease, we utilized islet cells antibodies (ICAs). The aim of this study was to evaluate the presence of ICAs among diabetic patients undergoing simultaneous transplantation of the pancreas and kidney (SPK). Twenty-six diabetic patients received an SPK, 12 of whom were included in this analysis. The indirect immunofluorescence method was utilized for quantitation of ICAs. The types of ICAs were no different following transplantation of the pancreas. The serum levels of pre-existent ICAS in diabetic patients undergoing SPK with immunosuppression were not reduced, and they did not interfere with the function of the implanted pancreas over a period of 60 days.

Surgery for bronchiectasis

OBJECTIVE

The incidence of bronchiectasis has declined markedly in developed countries. However, a reasonable number of patients still need surgery, despite aggressive physiotherapy and antibiotic therapy. We have reviewed our patients to clarify the benefits from surgery and to analyse the complications.

MATERIAL AND METHODS

Between 1988 and 1999, we have operated on 119 patients with bronchiectasis, 71 female and 48 male, with a mean age of 42.2 years (range 11--77 years). Surgery was indicated because of unsuccessful medical therapy in 66 patients (55%), 31 (26%) had haemoptysis, 11 (9.2%) had lung abscess, 10 (8.4%) had lung masses, and three (2.5%) had pneumothorax. The most common manifestations were cough with sputum in 90 patients (76%), haemoptysis in 45 (38%) and recurrent infections in 57 (48%). The mean duration of the symptoms was 4 years (range 1--40 years). The lower lobes were diseased in 61 patients and bilateral disease was found in ten. The mean number of involved pulmonary segments was five (range 1-15). A lobectomy was performed in 75 patients (62%), a segmentectomy in 12 (10%), a pneumonectomy in nine (7.4%) and a bilobectomy in four (3.3%). Complete resection of the disease was achieved in 108 cases (91%).

RESULTS

There was no operative mortality and perioperative morbidity occurred in 15 patients (15%), including temporary broncho-pleural fistulae in 7 (5.8%), and post-operative haemorrhage and atrial arrhythmias in four (3.3%) each. After a mean follow-up was 4.5 years, 73 patients (68%) of this group were asymptomatic, and 31 (29%) had meaningful clinical improvement, while only four (3.7%) maintained or worsened prior symptoms. The best clinical improvement occurred in patients with complete resection of the disease (P=0.008). There were no differences in the respiratory function, comparing pre- and post-operative data, with a 2-year of minimum interval. The VC was 91 and 89% and the FEV1 was 83% and 81% of expected, respectively before and after surgery, (P=NS).

CONCLUSION

Surgery of pulmonary bronchiectasis has few complications and markedly improves symptoms in the great majority of patients, especially when complete resection of the disease is achieved. Pulmonary resection of bronchiectasis does not alter respiratory function.

[Critical analysis of the use of corticosteroids in the neonatal period]

OBJECTIVE: To review the use of corticosteroids in the treatment of newborns with chronic lung disease, adrenal insufficiency and upper airway edema. SOURCES: Review of the available medical literature on the use of corticosteroids in newborns. SUMMARY OF THE FINDINGS: Although there is evidence of short-term clinical improvement of chronic lung disease with the administration of dexamethasone, the available literature did not show significant reduction in neonatal morbidity and mortality associated with this condition. CONCLUSIONS: The use of corticosteroids must be carefully analyzed and restricted to the treatment of severe cases, since these drugs may produce irreversible effects on the nervous system and neurological development of newborns.

Quality of life in patients undergoing coronary revascularization

INTRODUCTION

This study was aimed at the evaluation of the impact of coronary revascularization surgery on the quality of life (QOL) and identification of some variables which may contribute to influence the patients' own perception of their health condition.

METHODOLOGY

We prospectively studied 150 consecutive patients subjected to isolated coronary bypass surgery during a 3-month period, with evaluation of their perception of QOL before surgery and 6 months thereafter. The measurement instruments used were the MOS Health Survey (SF-36) and the Nottingham Health Profile (NHP). Additionally, a questionnaire for identification of lifestyles was introduced.

RESULTS

The majority of the patients were male (94%), above 50 years of age (81%), with a low educational level (65%), married (90%) and pensioners (44%). About one third (38%) had marked physical limitations (CCS class III/IV), with comorbidity (80%), previous myocardial infarction (49%) and 3-vessel coronary disease (68%). There was no operative mortality, but 29% had postoperative complications, albeit minor in the majority. Admission time was less than 8 days in 88.6% of the cases. Surgery proved beneficial in improving QOL, with better perception after surgery in all dimensions of both measurement instruments (p < 0.001). A higher level of education was related to a better perception of the energy dimension, married patients had a better improvement in the dimensions of physical pain and social isolation. More severe preoperative angina determined less favourable scores in the dimensions of mental health, social function and vitality; comorbidity had a negative impact on vitality and physical mobility; and the number of risk factors and postoperative complications had a negative impact on the dimensions of energy and emotional reactions, and social isolation and physical function, respectively. Six months after surgery, 62% of the patients who were still working before surgery had resumed their professional activity, but about 20% had retired; the majority had adopted healthier lifestyles with a decrease in tobacco and alcohol consumption and a more balanced diet.

CONCLUSIONS

Coronary revascularization substantially improves QOL, with a significant impact on the clinical variables of the psycho-social dimensions.

Divided left atrium associated with supravalvar mitral ring

Reported is a case with a rare association of divided left atrium, supramitral stenosing ring of the left atrium, connection of the left superior caval vein to the roof of the left atrium, unroofed coronary sinus with an interatrial communication at the mouth of the unroofed sinus and ventricular septal defect. The need for a complete echocardiographic examination in the presence of pulmonary venous obstruction is emphasized. Surgery was successful in spite of significant preoperative pulmonary hypertension.

Excision of pulmonary metastases of osteogenic sarcoma of the limbs

OBJECTIVE

The combination of surgery and chemotherapy improves the prognosis of patients with osteogenic sarcoma of the limbs without detectable metastases at presentation. However, lung metastases are a frequent complication. To evaluate the role of the resection of pulmonary metastases of osteogenic sarcoma of the limbs, we have reviewed our experience with this type of surgery, combined with a multidrug chemotherapy protocol.

PATIENTS AND METHODS

From January 89 to December 97, 198 patients operated on for osteogenic sarcomas of the limbs were followed in our centre. Of these, 31 patients (15.7%), with a mean age of 25 years (range 10-54 years), developed lung metastases and had undergone 45 thoracotomies. All patients received chemotherapy, followed by resection of metastatic lesions and additional chemotherapy. The mean time interval between resection of the primary tumour and the diagnosis of lung metastases was 22 months (4-122 months). Eight patients (25.8%) needed more than one (2-4) thoracotomy. The mean time interval between the first and second thoracic surgeries was 9.2 months (2-14 months).

RESULTS

There was no operative mortality or major morbidity. During the 45 thoracotomies, five lobectomies and 40 wedge resections were necessary. The mean number of metastases resected per thoracotomy was 3.4 (range 1-10). The degree of necrosis was evaluated by seriated sections for a histologic study. In the end the mean necrotic volume was calculated. A strong correlation was found between the degree of necrosis of the metastases and the need for reoperation for new metastatic lesions, because all the patients who needed more than one operation had less than 80% of necrosis of metastases. The patients were followed for a mean period of 28 months (6-72 months). Ten patients (32.2%) died of related causes at a mean of 19.4 months after thoracic surgery, three of whom had more than one operation. The 3-year survival after metastasectomy was 61%. Patients without pulmonary metastases had a 3-year survival of 79%.

CONCLUSIONS

In patients with lung metastases of an osteogenic sarcoma, the combination of chemotherapy and surgery improves the outcome. In our series the mortality was not influenced by the number or thoracotomies required.

Procedures for developing a simple scoring method based on unsophisticated criteria for screening children for tuberculosis

OBJECTIVE

To develop a scoring system for screening children for tuberculosis (TB) and for selecting suspects for further investigation in tuberculosis control programmes. Application of the score model, which would not require sophisticated or expensive technology, would be directed towards resource-poor countries with high prevalences of tuberculosis, where health care workers have to deal with diagnostic problems away from district hospitals or diagnostic facilities.

DESIGN

Based on contributions from members of an IUATLD task group from 10 countries on the use of diagnostic criteria in childhood tuberculosis, criteria were selected to be used as elements in a score model. Data were collected by standardised questionnaire on 879 subjects aged under 15 years. Of these, 794 were considered probable or confirmed cases of tuberculosis by the diagnosing doctors. From each record, the criteria/procedures used in the diagnosis of probable/confirmed TB and regarded by the doctors as relevant criteria were selected. Bacteriology, histology and chest radiography were used either singly or collectively as the definitive reference (gold standard) against which the more subjective criteria (symptoms, clinical signs, skin test) would be evaluated. The latter criteria cited as relevant were then ranked and further explored for inclusion in the score model. The relative importance of each criterion to every other criterion on the list was expressed as weights, determined by employing a logarithmic least squares method to solve the ratio scale estimation problem which underlies decision-making involving more than one criterion. The resultant values were then assigned to each criterion in the final score model.

RESULTS

The five clinical criteria thought to be most relevant as predictors of disease in children were history of contact with a case of tuberculosis, positive skin test, persistent cough, low weight for age, and unexplained/prolonged fever. In selecting the optimal cut-off points for the model at which tuberculosis would be suspected, low sensitivity and specificity (below 70%) but reasonably good positive predictive values (60%-77%) were obtained, depending on age group and epidemiological setting. In low tuberculosis prevalence settings, heavy reliance is placed by the model on a history of contact with a household case of tuberculosis and on a positive skin test, both of which have to be true. For high prevalence settings, more or less equal weighting is assigned to all five elements. Case contact and skin tests are less important, with low body weight, prolonged fever and cough being more indicative of tuberculosis.

CONCLUSION

The model provides for epidemiological differences between target populations and should prove successful as a screening tool to select children for further investigation by radiography and bacteriology.

Brucella endocarditis of the aortic valve

Brucella endocarditis was diagnosed in two patients with acute renal failure. Both patients had major aortic insufficiency, congestive cardiac failure and clinical and laboratory signs of an active infection, although adequate antibacterial therapy had already been introduced. Replacement of the aortic valve, together with the aortic root in one of the cases, were carried out as emergency procedures, followed by antibacterial treatment with rifampicin, doxycycline and co-trimoxazole. Both patients left the hospital cured and are well 2.5 and 2 years after the surgery, respectively.

[Surgery for acute type-A aortic dissection]

From January 1989 through June 1996, 29 patients underwent surgical repair of type A acute aortic dissection. Mean age was 59 +/- 13.5 years (range 25-76 yrs) and 21 patients (72.4%) were male. Nineteen patients (65.5%) had systemic hypertension and 3 (10.3%) Marfan syndrome. One patient (3.4%) had prior surgical repair of descending aortic dissection and CABG. Six patients (20.7%) were operated on in shock. The dissection was limited to the ascending aorta (DeBakey type II) in 12 patients (41.4%). Eleven patients (37.9%) had severe aortic regurgitation. Replacement of the ascending aorta was performed in all cases and extended to include the transverse arch in one. Twenty-three patients (79.3%) were operated upon using a tubular graft (sacron-21, homograft-2) with aortic valve resuspension. In the remaining 6 (20.7%) the aortic valve and root were replaced using a Bentall procedure, modified with a homograft in 3 cases. Five patients (17.2%) had associated surgery: CABG (4) and closure of aortic-atrial fistula (1). Mean cardiopulmonary bypass time was 134 minutes (range 70 to 285 min) and aortic cross-clamp time was 58 minutes (range 23 to 93 min). Hypothermic circulatory arrest for open distal anastomosis was used in 26 patients (89.7%) (mean time 22 min; range 10 to 32 min), with retrograde cerebral perfusion in the last 4 years (18 cases; 62.1%). Hospital mortality was 17.2% (5 patients). Eight patients (27.6%) had hospital morbidity: reexploration for bleeding (4 cases), CVA (3), A-V block necessitating permanent pacemaker (1). The mean time of hospitalization was 18 days (range 9 to 81 days). In the follow-up period (mean 38 mths; range 4 to 94 mths), 2 patients died (CVA and gastrointestinal bleeding) and 4 required hospitalization (perforated duodenal ulcer, peritonitis, suspected endocarditis, supraventricular tachyarrhythmia-1 patient each). All 22 survivors (75.9%) returned to the functional status they had prior to the dissection and 18 of them (81.8%) are in NYHA functional class I. Type A acute aortic dissection is a complex pathology and the postoperative mortality remains significant, but surgery permits good functional recovery and an active life for the survivors.

[Left ventricular aneurysm. The surgical results and follow-up]

From May 1988 through October 1994, 44 patients with ischemic left ventricular aneurysm were operated upon. The mean age was 60.5 +/- 7.7 years and 36 patients (81.8%) were male. Thirty-two patients (72.7%) had congestive heart failure in NYHA class II or greater and 26 (59.1%) had moderate or severe left ventricular dysfunction. In 41 cases (93.2%) there was a history or electrocardiographic signs of myocardial infarction and only 3 patients (6.8%) were angina free. The location of the aneurysms was antero-apical or antero-lateral in 37 patients (84.1%) and inferior in 7 (15.9%), and intracavitary clot was present in 9 cases (20.5%). Fifteen patients (34.1%) were operated upon using standard linear repair, 8 (18.2%) by Stoney's technique and in the remaining 21 (47.7%) an endoventricular patch plasty was performed. All patients but one had CABG with a mean of 2.7 grafts per patient. The IMA was used in all patients with graftable LA disease (90.0%). Double IMA grafting was used in 10 patients (22.7%). Three patients (6.8%) had associated valvular surgery. Hospital mortality was 2.3% (1 patient) and morbidity 22.7% (10 patients); intra-aortic balloon counterpulsation was required in two patients. The mean time of hospitalization was 13.5 +/- 9.0 days. In the follow-up period (mean 29.2 +/- 21.5 months), 6 patients had required hospitalization (left ventricular failure -4; supraventricular arrhythmia-2) and two died. The remaining 32 survivors (78.0%) are in functional class I of the NYHA, without angina. Surgery of left ventricular ischaemic aneurysm was possible with low mortality and morbidity, with good functional results.

[Homograft replacement of aortic valve and ascending aorta]

From May 1990 through December 1994, integral valved aortic homografts were implanted for replacement of the aortic valve and of part or the whole of the ascending aorta in 24 patients with a mean age of 45.5 years (17-66 years). Ten patients (41.7%) had infective endocarditis of the aortic valve (4 of the native valve and 6 prosthetic). Seven of these had root abscesses (70%), one with a fistula to the right atrium, resulting in a variable degree of discontinuity between the left ventricle and the aorta. Twelve patients (50%) had ascending aortic aneurysms and the remaining two (8.3%) had aortic dissection. Three patients (12.5%) also had mitral pathology, one had triple vessel coronary disease, one had aortic coarctation and another one had a sub-aortic membrane. Two thirds of the patients were in NYHA class III/IV and 10 (41.7%) had moderate or severe left ventricular dysfunction. A modified Bentall technique utilising fresh aortic homografts was used in all patients. The homografts were harvested aseptically from donors with a mean age of 30 years (16-54 years) and preserved at 4 degrees C for a period of 1-43 days (median-13 days). Six patients (25%) had associated surgery: mitral valve replacement; mitral valvuloplasty with a ring; closure of aortic- atrial fistula, resection of sub-aortic membrane; triple coronary artery bypass; and mitral and tricuspid annuloplasty and closure of ASD (one patient each). Postoperatively three patients (12.5%) required reexploration for excessive blood drainage in the first hours and one patient with complete A-V block required a pacemaker (4.2%). Hospital mortality was 4.2% (one patient). At the time of discharge, no patient had significant Doppler or echocardiographic aortic gradient or regurgitation. All patients were followed for a mean period of 31 months (7-62 months). One patient died of a non cardiac death and the remainder are in NYHA class I without thromboembolic or haemorrhagic accidents and with echocardiographic findings similar to those observed at discharge. These results suggest that aortic homografts constitute an effective and safe method of reestablishing the continuity between left ventricle and aorta, especially in the presence of an infective process with root abscesses.

[The Bland-White-Garland syndrome or an anomalous origin of the left coronary from the pulmonary artery. Apropos a case of a continuous murmur in an adult]

The authors report a case of anomalous origin of the left coronary artery from the trunk of pulmonary artery in an adult without significant symptoms, diagnosed by the presence of a continuous thoracic murmur. Because its low incidence and great mortality in the beginning of life, the appearance in the adult is extremely uncommon, especially without symptoms of cardiac failure, angina pectoris or myocardial infarction. In the present case, the patient was asymptomatic and was submitted to various echocardiograms before the diagnosis was suspected and confirmed with angiography. Surgical treatment was performed successfully with reimplantation of the anomalous vessel in the aorta.

The clinical value of screening chest radiography in the neonate with lung disease

To examine the role of routine chest radiography in the management of the critically ill neonate with pulmonary disease, 41 term and preterm infants with lung diseases were prospectively evaluated. Seventy radiographs (35%) were obtained for clinical indications and 128 (65%) for prospective screening. Studies were compared with each infant's most recent previous study, if available. Every exam was designated Level I, if the radiograph identified a new finding that required clinical intervention; Level II, if an abnormality or interval change was observed that did not require immediate intervention; or Level III, if there was no interval change since the previous radiograph. Thirty-three (47%) indication radiographs and 63 (49%) screening radiographs showed significant changes since the previous study. Twenty-four (34%) of the indication radiographs and 42 (33%) of the screening radiographs had Level I abnormalities (P = NS). Nine (13%) of the indication radiographs and 21 (16%) of the screening radiographs had Level II abnormalities (P = NS). Results suggest that routine screening chest radiographic studies are an important adjunct of care in critically ill newborns with respiratory disease and may identify potential problems before they are reflected in a change in clinical status.

[Aortocoronary bypass. Intermittent clamping of the aorta versus cardioplegia]

STUDY OBJECTIVE

Cardioplegia is the standard method of myocardial protection during aorto-coronary bypass surgery. However, there are other alternatives which the authors intend to test.

DESIGN

Forty consecutive, non-selected cases of coronary artery bypass surgery done with intermittent aortic crossclamping (Group A) are compared with the 40 preceding consecutive cases where cardioplegia was used (Group B).

PATIENTS

The mean age of the patients of group A was 57.5 years (range 42-69 years) and that of group B was 57.1 years (range 39-76 years). Patients of group A had an incidence of previous myocardial infarct of 42.5% against 65.0% in group B. Chronic angina led to surgery in 33 cases of group A and in 32 of group B. The remainder (18.8%) had unstable angina.

INTERVENTIONS

The mean number of grafts per patient was 2.9 in group A and 3.2 in group B. Internal mammary arteries were used in most patients of both groups, with 61 anastomoses in group A (1.5/patient) and 57 in group B (1.4/patient). The mean ischaemic time per graft was 7.4 min (range 5.5-11 min) in group A and 15.6 min (8.5-22 min) for group B.

MAIN RESULTS

Serial analysis of myocardium-specific serum enzymes and the CPK-MB/total CPK ratio has not evidenced perioperative infarction in any patient of either group. Although enzyme levels were slightly higher in group A, the difference has not reached statistical significance. However, the electrocardiograms have shown one perioperative infarct in each group. Vasodilators were generally used in the 2 groups, for a mean of 16.8 hours, while inotropic drugs were required in only 4 cases of group A and 3 of group B. There has been no hospital mortality in either group.

CONCLUSIONS

These results, in a series of non selected patients, demonstrate that intermittent crossclamping may be an acceptable alternative method of myocardial protection during aorto-coronary bypass surgery thus made simple, quick and secure.

[Primary heart tumors. Report of a clinical case]

The authors describe the case of a 52-year-old patient with several hospitalizations due to acute pulmonary edema, clarified only during the performance of cardiac surgery for the correction of presumable mitral valvular pathology. A leiomiossarcome of the left auricle was concerned, which involved the posterior ring of the mitral valve, the interauricular septum and the orifices of the pulmonary veins. Due to the impossibility of proceeding with the complete resection of the tumor, the tumoral mass was wasted away in order to liberate the involved structures, this followed by chemotherapy. Two years since, the patient shows a generally deteriorated state, submitted to various hospitalizations due to cardiac insufficiency, having been objectivated hepatic metastization and recurrence of the primary neoplasm.

[Cor triatriatum. Echo/Doppler diagnosis followed by immediate surgical correction. Report of a clinical case]

As Cor Triatriatum is a rare congenital cardiopathy and benign after corrective surgery, decisive means of diagnosis are essential. The AA review some descriptive theoretical concepts and make reference to the difficulties, present at times, in diagnosis by cardiac catheterization. They consider Eco-Doppler to be the means of excellence for its recognition describing all aspects that point to the diagnosis of this pathology. Described is the case of a 12 month old baby, in whom some semiological findings had lead to a wrong diagnosis. In the discussion, additional diagnosis is eliminated due to some anatomic characteristics defined by echocardiography.

Cardiac operation during active infective endocarditis: results of aortic, mitral, and double valve replacement in 94 patients

Cardiac valve replacement was performed in 94 patients (95 operations) in the presence of active infective endocarditis. Most of the patients were extremely ill. The operation was performed as an emergency or semiemergency lifesaving procedure in 88% of them, and more than half received little or no antibiotic treatment prior to the operation. The hospital mortality was 16%--14% for aortic valve replacement (AVR) and 11% for double valve replacement (DVR) but 31% for isolated mitral valve replacement (MVR). The mortality was not higher in patients operated on urgently (emergency or semiemergency), nor was it higher in patients who had aortic annular abscesses or aneurysms. Prosthetic valve endocarditis (PVE) (in each case occurring more than 60 days after the previous valve operation) carried a higher mortality (33%) than native valve endocarditis (NVE) (14%). The relatively high early mortality for MVR may have been related to the fact that we operated upon MVR patients after intensive medical treatment had failed. The late results were good: Sixty-six patients are alive and well, 51 of them in Functional Class I. Six patients were reoperated upon for aortic periprosthetic leaks, and five are now well. Eight patients died late (9%), one of them because of a periprosthetic leak and one because of a clotted valve. In seven of the eight deaths, the cause of death was probably not related to the timing of the original operation. We recommend early valve replacement for patients with infective endocarditis. We believe that early operation reduces mortality, prevents emboli, and is associated with excellent long-term results.