R.H.B. Santos

Validation of a cutoff value on echo Doppler analysis to replace right heart catheterization during pulmonary hypertension evaluation in heart transplant candidates.

BACKGROUND Heart transplantation (OHT) has traditionally been contraindicated in the presence of severe pulmonary hypertension (PH), as detected by right heart catheterization. Noninvasive methods are still not reliably accurate to make this evaluation. OBJECTIVES Determine the efficacy of echo Doppler analysis for the diagnosis of severe PH. METHODS One hundred thirty patients (mean age = 42 +/- 15 years, 82 men) showed severe left ventricular dysfunction (mean ejection fraction = 29 +/- 12%; functional class III-IV). We excluded patients with atrial fibrillation, heart failure secondary to congenital disease, and valvulopathy. The pulmonary parameters defined as severe PH were: systolic pulmonary artery pressure (sPAP) >or= 60 mm Hg; a mean transpulmonary gradient >or= 15; or pulmonary vascular resistance >or= 5 Wood units. Patients underwent a right heart catheterization using a Swan-Ganz catheter to measure hemodynamic parameters and to noninvasively estimate right-sided pressures from spectral Doppler recordings of tricuspid regurgitation velocity (right ventricular systolic pressure [RVsP]). A Pearson correlation of sPAP was obtained with RVsP by; the sensitivity of RVsP for the diagnosis of PH was determined by a receiver operating characteristic (ROC) curve. RESULTS A good correlation between sPAP and RVsP was obtained by Pearson correlation analysis (r = 0.64; 95% confidence interval [CI] 0.50-0.75; P < .001). The ROC curve analysis showed a sensitivity of 100%, a specificity of 37.2%, (95% CI 0.69-0.83, P < .0001) of a RVsP < 45 mm Hg (cutoff) on the exclusion of severe PH. CONCLUSIONS The cutoff of RVsP < 45 mm Hg, on noninvasive echo Doppler evaluation of PH is an efficient method to replace invasive heart catheterization in OHT candidates.

Successful Endomyocardial Biopsy Guided by Transthoracic Two-Dimensional Echocardiography

INTRODUCTION Two-dimensional (2-D) echocardiography is an excellent alternative method to perform endomyocardial biopsies (EB) in special situations, mainly when the patient is in a critical state and cannot go to the catheterization laboratory or when there are contraindications to the use of fluoroscopy as in the pregnancy. OBJECTIVE This single-center experience analyzed the last 25 years use of an EB technique guided by echocardiography realized at the bedside on critical patients. METHODS From 1985 to 2010, we performed 76 EB guided by 2-D echocardiography on 59 patients, among whom 38 (64.4%) were critically ill with examinations at the bedside; among 10 (16.9%) subjects, the procedure was carried out simultaneously with fluoroscopy for safetys sake during the learning period. In addition, 8 (13.6%) were unavailable for fluoroscopy, and 3 (5.1%) required a hybrid method due to an intracardiac tumor. RESULTS The main adverse effects included local pain (n = 4, 5.6%); difficult out successful puncture due to previous biopsies (n = 4, 5.6%); local hematoma without major consequences (n = 3, 4.2%); failed but ultimately successful puncture on the first try due to previous biopsies or (n = 3, 4.2%); obesity and immediate postoperative period with impossibility to pass the bioptome into the right ventricle; however 2 days later the procedure was repeated successfully by echocardiography (n = 1, 1.4%). All myocardial specimens displayed suitable size. There were no undesirable extraction effects on the tricuspid valve tissue. In this series, there was no case of death, hemopericardium, or other major complication as a direct consequence of the biopsy. CONCLUSION 2-D echocardiography is a special feature to guide EB is mainly in critically ill patients because it can be performed at the bedside without additional risk or disadvantages of fluoroscopy. The hybrid method associating 2-D echocardiography and fluoroscopy allows the procedure in different situations such as intracardiac tumor cases.

Long-Term Pulmonary Vascular Reactivity After Orthotopic Heart Transplantation by the Biatrial Versus the Bicaval Technique

INTRODUCTION Advantages of the bicaval versus the biatrial technique have been reported, emphasizing atrial electrical stability and less tricuspid regurgitation. OBJECTIVE To analyze the impact of the surgical technique on long-term pulmonary pressures, contractility, and graft valvular behavior after heart transplantation. METHODS Among 400 orthotopic heart transplantation recipients from 1985 to 2010, we selected 30 consecutive patients who had survived beyond 3 years. The biatrial versus bicaval surgical technique groups included 15 patients each. Their preoperative clinical characteristics were similar. None of the patients displayed a pulmonary vascular resistance or pulmonary artery pressure over 6U Wood or 60 mm Hg, respectively. We evaluated invasive hemodynamic parameters during routine endomyocardial biopsies. Two-dimensional echocardiographic parameters were obtained from routine examinations. RESULTS There were no significant differences regarding right atrial pressure, systolic pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, cardiac index, systolic blood pressure, left ventricular ejection fraction, and mitral regurgitation (P > .05). Tricuspid regurgitation increased significantly over the 3 years of observation only among the biatrial group (P = .0212). In both groups, the right atrial pressure, pulmonary wedge capillary pressure, transpulmonary gradient, and pulmonary vascular resistance decreased significantly (P < .05) from the pre- to the postoperative examination. In both groups cardiac index and systemic blood pressure increased significantly after transplantation (P < .05). Comparative analysis of the groups only showed significant differences regarding right atrial pressure and degree of tricuspid regurgitation; the bicaval group showing the best performance. CONCLUSIONS Both surgical techniques ensure adequate left ventricular function in the long term; however, the bicaval technique provided better trends in hemodynamic performance, as well as a lower incidence and severity of tricuspid valve dysfunction.

Principal Component Analysis in Multivariate Microphones Response to Simulated Leakage in Metal Pipeline of Compressed Air

Systems capable of diagnosing and characterizing a leakage in pipes are important not only to avoid losing material, but also for human health. For instance, in a building, a leakage of inflammable gas through pipes may lead to huge fire injuries or intoxication. For analysing the existence of gas material escaping from pipes, the acoustic method acts investigating the sounds signals in situations without leakage and in situations with simulated leakage. Microphones coupled to the lab scaled gas distributor pipe capture the acoustic signals in time which are further decomposed in their frequencies components by Fast Fourier Transform (FFT). Thus, a principal component analysis (PCA) is applied considering the amplitudes, in the respective frequency accused by the FFT method, as variables. It is revealed that it is possible to represent the system in smaller dimension size in which much of the original information preserves. For instance, plotting data in three dimensions, in terms of the three principal components, the representativity, or explained variance, is greater than 70% and some patterns become visually enlightened. In fact, 78 components are enough to get representativity greater than 90% against the original data that had the observations distributed in 6599 different amplitudes in frequency domain. In time domain, it is possible to note that the average absolute amplitude response from the microphones increases after disturbance but the farther it is its position related to the source of disturbance, the less it tends to increase.

MONITORING FLEXIBLE GAS PIPELINE WITH A MICROPHONE AND ARTIFICIAL NEURAL NETWORKS

Pipeline networks are complex systems of ducts transporting gas and chemical products through long distances. With the purpose to track these leaks a technique, based on the analysis of sound noises ca ptured by a microphone and on pressure transients generate d by leak occurrence, was developed. Neural Artificial Networks were applied to determine leak magnitude and leak location. The experimental results showed that it is possible to detect leaks in pipelines. The dynamics of these noises in time were used as input to the neur al model to determine the location and magnitude of th e leaks.