Effect of vessel size on the flow efficiency of the total cavopulmonary connection: in vitro studies.

The total cavopulmonary connection (TCPC) creates a passive system of blood flow into the pulmonary circulation. We hypothesize that the efficiency differences found in models with superior vena cava-inferior vena cava (SVC-IVC) offsets is dependent on vessel size, with flow efficiency improving with larger size vessels. Two sets of in vitro TCPC models (TCPC-3 and TCPC-15) were constructed corresponding to average vessel diameters of 3- and 15-year-old patients. The model with full SVC-IVC offset was the most efficient in TCPC-3 models. There was no significant difference between geometric arrangements in TCPC-15 models; however, the average efficiencies were significantly higher. Among the models representing vessel sizes of the younger age group, the model with the full-diameter SVC-IVC offset was the most efficient. The models representing vessel sizes of the older age group showed marked improvement in efficiencies throughout without obvious differences between various geometric arrangements. This suggests that geometric considerations in TCPC surgical techniques may be of lower than expected significance over the life span of a patient. More important, after balancing the effects of improved flow efficiency with larger vessels against the effects of chronic volume overload, the trend of performing the Fontan surgery on increasingly younger patients may need to be reconsidered after further studies.

Artificial neural network-based method of screening heart murmurs in children.

BACKGROUND: Early recognition of heart disease is an important goal in pediatrics. Efforts in developing an inexpensive screening device that can assist in the differentiation between innocent and pathological heart murmurs have met with limited success. Artificial neural networks (ANNs) are valuable tools used in complex pattern recognition and classification tasks. The aim of the present study was to train an ANN to distinguish between innocent and pathological murmurs effectively. METHODS AND RESULTS: Using an electronic stethoscope, heart sounds were recorded from 69 patients (37 pathological and 32 innocent murmurs). Sound samples were processed using digital signal analysis and fed into a custom ANN. With optimal settings, sensitivities and specificities of 100% were obtained on the data collected with the ANN classification system developed. For future unknowns, our results suggest the generalization would improve with better representation of all classes in the training data. CONCLUSION: We demonstrated that ANNs show significant potential in their use as an accurate diagnostic tool for the classification of heart sound data into innocent and pathological classes. This technology offers great promise for the development of a device for high-volume screening of children for heart disease.

Echocardiographic outcome of infants treated as newborns with inhaled nitric oxide for severe hypoxemic respiratory failure.

OBJECTIVE: To determine the cardiovascular outcome of a group of term newborns treated with inhaled nitric oxide (iNO) for severe hypoxemic respiratory failure with associated persistent pulmonary hypertension. STUDY DESIGN: We performed echocardiographic evaluations in 40 survivors treated for severe neonatal hypoxemic respiratory failure. Each of the 40 had at least 2 follow-up echocardiograms at 3 or 6 and 24 months. These studies were compared with echocardiograms done in infants in a normal, age-matched control group. RESULTS: Three of 31 infants met echocardiographic criteria for pulmonary hypertension at the 3-month examination. Two of the 3 had associated structural heart disease (1 with an atrial septal defect and 1 with a ventricular septal defect). At 24 months only 1 patient had pulmonary hypertension. This infant had an atrial septal defect that was surgically closed shortly after the 24-month echocardiogram because of the pulmonary hypertension. Group comparisons of 3- and 24-month echocardiographic variables showed no differences between the study and control groups. In the 31 infants in whom serial studies were completed, expected age-related changes were demonstrated between the 3- and 24-month examinations. CONCLUSIONS: The incidence of residual pulmonary hypertension in infants treated as newborns for severe hypoxemic respiratory failure is low. The group at highest risk is those with structural heart disease.

Cine magnetic resonance imaging and color Doppler flow mapping in infants and children with pulmonary artery bands.

Cine magnetic resonance imaging (MRI) and color Doppler flow mapping were performed in 12 infants and children (aged 3 to 35 months) after pulmonary artery banding to define the anatomy and physiology of the right ventricular outflow tract and evaluate the anatomy. MRI was performed using a 1.5 Tesla magnet in the sagittal, axial and oblique views with all patients studied in the 24 cm head coli following adequate sedation. High-resolution cine MRI was obtained in all patients and the narrowest flow diameter on cine MRI correlated well with the pressure gradient measured across the band in 11 patients at cardiac catheterization or surgery (r = -0.95). Signal loss was always seen distal to the band associated with turbulent flow as seen by color Doppler flow mapping. Signal loss in cine MRI was also seen proximal to the band. The length of this proximal signal void also correlated well with the pressure gradient measured across the band (r = 0.91) and was closely matched by the zone of proximal spatial acceleration defined by digital computer analysis of color Doppler flow map images (r = 0.89), which also demonstrated low grade variance associated with the laminar accelerating flow stream. The position of the band was accurately defined by cine MRI which identified inadequate pulmonary artery banding in 2 patients confirmed subsequently at cardiac catheterization and angiography. Cine MRI and color Doppler flow mapping when used together provide high-resolution detail about the right ventricular outflow tract and pulmonary artery band anatomy and function.(ABSTRACT TRUNCATED AT 250 WORDS)

Color Doppler diagnosis of mechanical prosthetic mitral regurgitation: usefulness of the flow convergence region proximal to the regurgitant orifice.

In prosthetic or paravalvular prosthetic mitral regurgitation, transthoracic color Doppler flow mapping can sometimes fail to detect the regurgitant jet within the left atrium because of the shadowing by the prosthetic valve. To overcome this limitation, we assessed the utility of color Doppler visualization of the flow convergence region (FCR) proximal to the regurgitant orifice in 20 consecutive patients with mechanical prosthetic mitral regurgitation documented by surgery and cardiac catheterization (13 of 20 patients). In addition, we studied 33 patients with normally functioning mitral prostheses. Doppler studies were performed in the apical, subcostal, and parasternal long-axis views. An FCR was detected in 95% (19 of 20) of patients with prosthetic mitral regurgitation. A jet area in the left atrium was detected in 60% (12 of 20) of patients. In 18 of 19 patients with Doppler-detected FCR, the site of the leak was correctly identified by observing the location of the FCR. A trivial jet area was detected in eight patients with a normally functioning mitral prosthesis; in none was an FCR identified. Thus color Doppler visualization of the FCR proximal to the regurgitant orifice is superior to the jet area in the diagnosis of mechanical prosthetic mitral regurgitation. Moreover, FCR permits localization of the site of the leak with good accuracy.

Color Doppler flow mapping in patients with coarctation of the aorta: new observations and improved evaluation with color flow diameter and proximal acceleration as predictors of severity.

We performed color Doppler flow mapping in 15 patients, 1 week to 17 years old (mean 42 months), with coarctation of the aorta that was confirmed subsequently by angiography and/or surgery. Twelve patients had native coarctation and three had mild recoarctation after surgical repair. Color Doppler flow maps were analyzed with a digital analysis package and a Sony computer system. The diameter in the region of coarctation from the color Doppler flow map (mean = 2.0 +/- 0.8 mm [SD]) correlated well with the coarctation diameter measured at angiography (mean = 1.8 +/- 0.8 mm; r = .83, SEE 0.43 mm) in the 10 patients with native coarctation undergoing angiography, but the coarctation diameter measured by two-dimensional echocardiography (3.9 +/- 1.5 mm) was poorly predictive of the angiographic severity (r = .23). Additionally, spatial acceleration was seen in all patients proximal to the coarctation site, with an aliased and accelerating stream narrowing progressively as it proceeded toward the coarctation site, a pattern that is not seen in healthy subjects. Computer analysis of the color Doppler images provided pseudo three-dimensional and digital velocity maps for blue, red, and green (turbulent) flow velocities to allow an enhanced appreciation of the accelerating stream, easily separating this from normal descending aortic aliasing patterns. The narrowing of the acceleration area in the proximal descending aorta (distal/proximal acceleration zone ratio) was also predictive of the angiographic severity of coarctation (r = .83). The distribution of low-level turbulence seen proximally paralleled the distribution of the proximal accelerating stream.(ABSTRACT TRUNCATED AT 250 WORDS)

Endomyocardial biopsy with fluoroscopic and two-dimensional echocardiographic guidance: case report of a patient suspected of having multiple cardiac tumors.

An 18-year-old female with multiple intracardiac masses was further evaluated using percutaneous endomyocardial biopsy of the right ventricle and right atrium. Fluoroscopy was used to visualize the course of the bioptome and simultaneous two-dimensional echocardiography was used to image the masses thus improving the surgeon's chance of obtaining diagnostic tissue.

Two-dimensional echo Doppler study of congenital disorders of the mitral valve.

To define the use of two-dimensional echocardiography (2DE) and Doppler methods for diagnosis of forms of congenital mitral stenosis, we studied 16 children, age range 2 months to 13 years, with congenital deformities of the mitral valve documented at cardiac catheterization. Thirteen had additional congenital heart defects, most commonly aortic stenosis or aortic coarctation. In eight patients features of mitral valve anatomy were observed and described during cardiac surgery and in one child the anatomy was verified by postmortem examination. 2DE studies allowed anatomic subclassification of 10 valves which had asymmetric or single dominant papillary muscles (parachute) and six which had arcade mitral valve attached by short chords to multiple diminutive papillary muscle heads. All patients' echoes exhibited shortened and thickened mitral chordae and doming of the mitral leaflets during diastole, and seven children had restricted mitral orifices imaged on the short-axis imaging plane. All seven of the patients studied by Doppler echocardiography had increased maximal transmitral inflow velocity (range 111 to 260 cm/sec) greater than the 95% confidence limits for mitral flow velocities in 34 normal children who served as the control group. Our study suggests that 2DE studies, especially when combined with Doppler interrogation, are sensitive for defining forms of congenital mitral stenosis.

Two-dimensional echocardiography for evaluation of metastatic cardiac tumors in pediatric patients.

We have studied five patients with metastatic cancer in whom two-dimensional echocardiography (2DE) demonstrated cardiac or pericardial involvement. Echo studies may guide the clinician in instituting and/or modifying cardiac and cancer therapy in such patients.

Clinical applications of Doppler echocardiography combined with two-dimensional cardiac imaging - a review

No presente artigo procuramos descrever os conceitos basicos bem como demonstrar os padroes normais de fluxo atraves das diferentes valvas cardiacas obtidos por meio da ecocardiografia Doppler combinada com imagem cardiaca obtida atraves da ecocardiografia bidimencional. Tambem descrevemos as mais recentes aplicacoes clinicas desta nova modalidade diagnostica. Enfoque especial foi dado a quantificacao de fluxo, isto e, medida estimativa do debito cardiaco e "shunts" esquerda - direita, bem como estimativa nao invasiva de gradientes pressoricos em pacientes acometidos de lesoes valvares tipo estenose. Enquanto maior experiencia se faz necessaria para aquisicao de conceitos definitivos, esta recente metodologia parece oferecer um novo campo para obtencao de dados de grande aplicabilidade clinica

Residual shunting in the early postoperative period after closure of atrial septal defect: echocardiographic comparison of patch materials.

Residual shunting after surgical closure of septal defects is a common postoperative complication. In this study, contrast echocardiography was used to assess the effect of different surgical patch materials on early postoperative residual shunting. The study consisted of 44 patients (aged 3 days to 64 years) with simple or complex atrial septal defects. Total pulmonary-to-systemic flow ratios ranged form 1.8:1 to 4.0:1. Three methods were used to close the atrial septal defects: primary suture closure (n = 7), patching with thin, knit Teflon fabric (n = 13), and patching with thicker, low porosity, knit Teflon fabric (n = 24). Contrast echocardiographic injections were performed through central venous and left atrial lines positioned at operation for monitoring purposes. Ten of the 44 patients had residual shunts. In five of them, daily contrast studies showed progressive diminution in shunting with eventual resolution, but in the other five patients, shunting persisted beyond the first 5 postoperative days. Three of the latter five required reoperation for actual residual anatomic defects. No patient whose atrial septal defect was closed by either direct suture or thick, low porosity Teflon fabric had shunting detected at any time postoperatively. Our data confirmed temporary leakage across newly implanted intracardiac patches. However, shunts that persist beyond the first postoperative week indicate true anatomic residua and not porous patch material. If a patient's recovery is complicated, use of contrast echocardiography can determine whether a residual shunt is a causative factor. In patients with complex lesions in whom continued shunting during the early postoperative period may cause serious hemodynamic consequences, heavier, low porosity patch material can be useful.

Utility of M-mode echocardiography for early identification of infants with persistent pulmonary hypertension of the newborn.

The clinical syndrome of persistent pulmonary hypertension of the newborn (PPHN) still carries high mortality in spite of improved neonatal care. The purpose of this prospective study was to assess the utility of M-mode echocardiography for the early identification of infants with PPHN prior to clinical deterioration. Echocardiograms of 51 infants who needed fractional inspiratory oxygen (FIO2) greater than or equal to 0.25 to maintain adequate PaO2 within 36 hours of life were compared to those of 115 healthy full-term and preterm newborns. Of the 51 infants, ten had elevated systolic time interval ratios of both ventricles simultaneously (ventricular pre-ejection period to ventricular ejection time [RPEP/RVET greater than or equal to 0.50, LPEP/LVET greater than 0.38]). All of these newborns had PPHN that was manifest clinically by 11 to 30 hours of age. The echocardiographic findings preceded clinical deterioration by at least one to five hours in all cases. The other 41 infants had clinical courses consistent with uncomplicated pulmonary disease. These data indicate that systolic time interval ratios, although not accurate measures of pulmonary arterial pressure and/or pulmonary vascular resistance, permit early identification of infants with PPHN and separation from others with uncomplicated pulmonary disease.

La ecocardiografia bidimensional en el estudio de los aneurismas del septum interventricular membranoso. / Bidimensional ecocardiography in the study of membranous ventricular septum aneurysms

Siete pacientes con aneurisma del septum interventricular membranoso asociado a comunicacion interventricular se estudiaron mediante ecocardiografia bidimensional. En todos los pacientes se visualizo un eco curvilineo, cupuliforme, convexo hacia el ventriculo derecho hacia el cual protruia en sistole y que partia de la parte alta del septum interventricular, immediatamente por debajo de la valvula aortica. Este hallazgo se identifico en todos en el plano de eje largo (7/7), en 4 de los 7 en plano de eje corto, en 4 de 6 en plano de las cuatro camaras desde el apex y en 3 de 6 en plano de las cuatro camaras desde la region subcostal. Cuarenta pacientes con diagnostico angiografico de comunicacion interventricular membranosa sin aneurisma septal se estudiaron mediante ecocardiografia bidimensional; en solo uno de ellos se encontraron hallazgos sugestivos de aneurisma de la porcion membranosa del septum interventricular, en los planos de eje largo y cuatro camaras desde el apex. Concluimos que la visualizacion, mediante ecocardiografia bidimensional, de un eco curvilineo, en el tercio proximal del septum interventricular, que protruye hacia el ventriculo derecho en cada sistole y que se identifica en varios planos, es muy sugestiva de aneurisma del septum interventricular membranoso. Este procedimiento parece ser aceptablemente especifico en el diagnostico de esta entidad