Biomedical subjects

A C Rodrigues

Publications and source records attributed to A C Rodrigues.

At least 19 recordsLinked to original sources

PubMed2006

The taxonomic and phylogenetic relationships of Trypanosoma vivax from South America and Africa.

The taxonomic and phylogenetic relationships of Trypanosoma vivax are controversial. It is generally suggested that South American, and East and West African isolates could be classified as subspecies or species allied to T. vivax. This is the first phylogenetic study to compare South American isolates (Brazil and Venezuela) with West/East African T. vivax isolates. Phylogeny using ribosomal sequences positioned all T. vivax isolates tightly together on the periphery of the clade containing all Salivarian trypanosomes. The same branching of isolates within T. vivax clade was observed in all inferred phylogenies using different data sets of sequences (SSU, SSU plus 5.8S or whole ITS rDNA). T. vivax from Brazil, Venezuela and West Africa (Nigeria) were closely related corroborating the West African origin of South American T. vivax, whereas a large genetic distance separated these isolates from the East African isolate (Kenya) analysed. Brazilian isolates from cattle asymptomatic or showing distinct pathology were highly homogeneous. This study did not disclose significant polymorphism to separate West African and South American isolates into different species/subspecies and indicate that the complexity of T. vivax in Africa and of the whole subgenus Trypanosoma (Duttonella) might be higher than previously believed.

Africa↗

PubMed2005

Phylogeny of Trypanosoma ( Megatrypanum ) theileri and related trypanosomes reveals lineages of isolates associated with artiodactyl hosts diverging on SSU and ITS ribosomal sequences.

SSU ribosomal sequences of trypanosomes from Brazilian cattle and water buffalo were used to infer phylogenetic relationships between non-pathogenic T. theileri and allied species parasitic in artiodactyls. T. theileri trypanosomes from distinct geographical regions in Brazil and from other countries were tightly clustered into the 'clade T. theileri' distant from the 'T. brucei clade' of pathogenic parasites of artiodactyls, and also distinct from trypanosomes of other mammals. The existence of this monophyletic assemblage (T. theileri clade) composed only by isolates from artiodactyl species justifies the continued recognition of the subgenus T. (Megatrypanum) with T. theileri as its type species. Phylogenies based on SSU and ITS1 ribosomal sequences produced the same branching pattern with isolates from different mammalian hosts clustered in 5 lineages: A, related to water buffalo; B, C and D, to cattle; E, to fallow deer. The pattern of host specificity allied to some congruence between host and parasite phylogenies suggested association of these trypanosomes with their respective hosts. Segregation of cattle isolates into three lineages revealed an overall geographical structure. Moreover, positioning of trypanosomes infecting tabanids in the T. theileri clade is consistent with the role of these flies as important vectors of these trypanosomes.

Animals↗

PubMed2005

High baseline serum total and LDL cholesterol levels are associated with MDR1 haplotypes in Brazilian hypercholesterolemic individuals of European descent.

The MDR1 gene encodes the P-glycoprotein, an efflux transporter with broad substrate specificity. P-glycoprotein has raised great interest in pharmacogenetics because it transports a variety of structurally divergent drugs, including lipid-lowering drugs. The synonymous single-nucleotide polymorphism C3435T and the nonsynonymous single-nucleotide polymorphism G2677T/A in MDR1 have been indicated as potential determinants of variability in drug disposition and efficacy. In order to evaluate the effect of G2677T/A and C3435T MDR1 polymorphisms on serum levels of lipids before and after atorvastatin administration, 69 unrelated hypercholesterolemic individuals from São Paulo city, Brazil, were selected and treated with 10 mg atorvastatin orally once daily for four weeks. MDR1 polymorphisms were analyzed by PCR-RFLP. C3435T and G2677T polymorphisms were found to be linked. The allelic frequencies for C3435T polymorphism were 0.536 and 0.464 for the 3435C and 3435T alleles, respectively, while for G2677T/A polymorphism allele frequencies were 0.580 for the 2677G allele, 0.384 for the 2677T allele and 0.036 for the 2677A allele. There was no significant relation between atorvastatin response and MDR1 polymorphisms (repeated measures ANOVA; P > 0.05). However, haplotype analysis revealed an association between T/T carriers and higher basal serum total (TC) and LDL cholesterol levels (TC: 303 +/- 56, LDL-C: 216 +/- 57 mg/dl, respectively) compared with non-T/T carriers (TC: 278 +/- 28, LDL-C: 189 +/- 24 mg/dl; repeated measures ANOVA/Tukey test; P < 0.05). These data indicate that MDR1 polymorphism may have an important contribution to the control of basal serum cholesterol levels in Brazilian hypercholesterolemic individuals of European descent.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Effect of the peroxisome proliferator-activated receptor-gamma C161T polymorphism on lipid profile in Brazilian patients with Type 2 diabetes mellitus.

AIM: The aim of the present study was to examine the effects of the C161T polymorphism of the peroxisome proliferator-activated receptor gamma (PPARgamma) gene in Brazilian subjects with Type 2 diabetes mellitus (T2DM) and controls residing in Sao Paulo City, Brazil. METHODS: Genomic DNA was obtained from 207 patients with T2DM and 170 unrelated normoglycemic individuals (CG). Anthropometric data included: body mass index, waist, hip, waist-to-hip ratio; biochemical parameters: fasting plasma glucose, total cholesterol, HDL- and LDL-cholesterol, triglycerides, glycated hemoglobin and insulin. Systolic and diastolic blood pressure was also measured. Screening for mutations in the entire coding region of the PPARgamma gene was carried out by PCR, single strand conformational polymorphism analysis (SSCP) and sequencing. C161T polymorphism was analyzed by PCR-RFLP. RESULTS: The C161T polymorphism was the only variant found in exon 6 of the PPARgamma gene. The frequency of the 161T allele in T2DM (0.10) was similar to that found in CG (0.07, p=0.210). Serum triglycerides (p=0.040), VLDL-cholesterol (p=0.040) and Atherogenic Index of Plasma (AIP; p=0.003) were significantly lower in 161T allele carriers than non-carriers in women of the T2DM group. CONCLUSIONS: Our results show that the C161T polymorphism in the PPARgamma gene is not associated with variables related to T2DM or insulin resistance in the Brazilian population. However, a reduction of serum triglycerides and AIP was observed in women with 161T allele of the C161T polymorphism of the PPARgamma gene.

Adult↗

PubMed2005

Association between Pro12Ala polymorphism of the PPAR-gamma2 gene and insulin sensitivity in Brazilian patients with type-2 diabetes mellitus.

AIM: Peroxisome-proliferator-activated receptor-gamma2 (PPAR-gamma2) is a nuclear receptor that plays an important role in lipid metabolism and insulin sensitivity. The purpose of this study is to investigate the association of Pro12Ala polymorphism at the PPAR-gamma2 gene in Brazilian patients with type-2 diabetes mellitus (T2Dm) and controls (CG). METHODS: Genomic DNA was obtained from 207 unrelated white people presenting with T2Dm and from 170 controls. Anthropometric data included body mass index and waist to hip ratio. Biochemical parameters included fasting plasma glucose, total cholesterol, high- and low-density lipoprotein cholesterol, triglycerides, glycated haemoglobin and insulin. Systolic and diastolic blood pressures were also measured. Screening for mutations in the entire coding region of the PPAR-gamma gene was performed by means of polymerase chain reaction (PCR), single-strand conformational polymorphism and sequencing. Pro12Ala polymorphism was analysed by using PCR-RFLP (restriction fragment-length polymorphism). RESULTS: One base substitution was identified - a C to G substitution in exon B of the PPAR-gamma2 gene. The frequency of the Ala12 allele in T2Dm (0.09) was similar to that found in CG (0.06, p = 0.185). In the T2Dm group, Ala12 allele was associated with lower fasting plasma insulin levels (p = 0.036) and higher insulin sensitivity (p = 0.049) by means of homeostasis model assessment. Among obese people, there was no association between any of the T2Dm or obesity-related traits and the Pro12Ala polymorphism. CONCLUSIONS: The results of our study suggest that people with the Ala12 allele of the PPAR-gamma2 gene could be more sensitive to insulin than those carriers of the Pro12 allele among Brazilian Caucasians.

Adult↗

PubMed2005

Evaluation of Petrifilm for the isolation of Staphylococcus aureus from milk samples.

Four experiments were conducted to evaluate the Petrifilm Staph Express Count plate (3M, Minneapolis, MN) for diagnosis of mastitis caused by Staphylococcus aureus. The objective of experiment 1 was to determine the sensitivity of Petrifilm compared with results of standard and augmented microbiological techniques, and the objective of experiment 2 was to compare microbiological results of composite and quarter milk samples processed using Petrifilm. Experiment 3 was conducted to determine the specificity of the Petrifilm method based on different interpretation parameters, and the objective of experiment 4 was to determine the repeatability of reading Petrifilm Staph Express plates. Results of standard microbiological techniques used for experiments 1 and 2 were compared with results of samples preprocessed using centrifugation or preincubation. The prevalence of recovery of Staph. aureus from milk samples processed using Petrifilm was significantly greater than the prevalence of milk samples processed using standard microbiological techniques. The sensitivity of isolation of Staph. aureus was 65.6, 75.0, 84.4, and 87.5% for standard, centrifugation, incubation, and Petrifilm methods, respectively. The occurrence of a distinct pink zone surrounding a colony was highly specific for Staph. aureus, and the specificity was 98.5 and 96.0% for experiments 3 and 4, respectively. The use of a weak pink zone to diagnose Staph. aureus resulted in a high rate of false-positive results. The interpretation of results of Petrifilm Staph Express was associated with the person that read the plates. Results from all 4 experiments indicate potential for the Petrifilm products as a diagnostic tool in some herd situations when Staph. aureus is the pathogen of interest. Results also indicate the need for standardization of interpretive criteria for personnel working with the products.

Animals↗

PubMed2004

Randomly amplified polymorphic DNA analysis of Trypanosoma rangeli and allied species from human, monkeys and other sylvatic mammals of the Brazilian Amazon disclosed a new group and a species-specific marker.

We characterized 14 trypanosome isolates from sylvatic mammals (9 from primates, 1 from sloth, 2 from anteaters and 2 from opossum) plus 2 human isolates of Brazilian Amazon. These isolates were proven to be Trypanosoma rangeli by detection of metacyclic trypomastigotes in the salivary glands of triatomines and by a specific PCR assay. Polymorphism determined by randomly amplified polymorphic DNA (RAPD) revealed that most (12) of the Brazilian T. rangeli isolates from the Amazon differed from those of other geographical regions, thus constituting a new group of T. rangeli. Four Brazilian isolates clustered together with a previously described group (A) that was described as being composed of isolates from Colombia and Venezuela. Isolates from Panama and El Salvador form another group. The isolate from Southern Brazil did not cluster to any of the above-mentioned groups. This is the first study that assesses the genetic relationship of a large number of isolates from wild mammals, especially from non-human primates. A randomly-amplified DNA fragment (Tra625) exclusive to T. rangeli was used to develop a PCR assay able to detect all T. rangeli groups.

Animals↗

PubMed2003

Brazilian isolates of Trypanosoma (Megatrypanum) theileri: diagnosis and differentiation of isolates from cattle and water buffalo based on biological characteristics and randomly amplified DNA sequences.

We detected and cultivated isolates of Trypanosoma (Megatrypanum) theileri from cattle and water buffaloes in São Paulo state, southeastern Brazil, which were characterized by comparing morphological, growth and molecular features. Although isolates from cattle and water buffalo were morphologically indistinguishable, they differed in their growth characteristics. A dendrogram based on randomly amplified polymorphic DNA (RAPD) patterns indicated close-genetic relationships among all isolates from both species, which were all tightly clustered together and distant from Megatrypanum species from wild mammals. In addition, isolates within the T. theileri-cluster were clearly segregated into two host-associated groups. The sequence of a synapomorphic RAPD-derived DNA fragment (Tth625), which was shared by all T. theileri trypanosomes from cattle and buffalo but not detected in any of 13 other trypanosome species, was used as target for a conventional T. theileri-specific PCR assay. We also defined RAPD fragments (Tthc606 and Tthb606) that distinguished cattle from buffalo isolates. Thus, distinct growth features and genetic variability distinguished between isolates from cattle and water buffaloes of the same geographic origin, suggesting an association of these isolates with their host species. The trypanosomes from water buffalo reported here are the first T. theileri-like isolates from the Asiatic buffalo (Bubalus bubalis) to be continuously cultured and compared with cattle isolates using biological and molecular methods.

Animals↗

PubMed2003

Morphometry and histochemistry of the semitendinosus muscle of tufted capuchin monkeys (Cebus apella Linnaeus, 1758).

Considering monkeys are animals closely related to the human, and semitendinosus muscle has been used in many postural research experiments, we have decided to study its histochemical characteristics. Samples were removed from the proximal, middle and distal regions of the semitendinosus muscles of five adult male tufted capuchin monkeys and observed for reaction with m-ATPase (with alkaline and acid pre-incubation), nicotinamide adenine dinucleotide tetrazolium reductase, and haematoxylin and eosin. The muscle fibres were classified as fast glycolytic (FG), fast oxidative glycolytic (FOG) and slow oxidative (SO) and quantified in terms of frequency and area. The three regions of the semitendinosus muscle showed no significant differences in frequency or area of the respective fibre types, and therefore the muscle can be considered histoenzymologically homogeneous. FG fibres presented higher frequencies and larger areas. The sum of FOG and SO fibres was 57.5%, suggesting that the semitendinosus muscle of the tufted capuchin monkey is adapted to an action involved in posture maintenance and in long arboreal dislocation. The present data agrees with the notion of differentiated quadrupedalism in some primates, which support a lower percentage of their weight on the fore limbs.

Analysis of Variance↗

PubMed2003

Three-dimensional distribution of GFP-labeled Pseudomonas putida during biofilm formation on solid PAHs assessed by confocal laser scanning microscopy.

Confocal laser scanning microscopy was used to monitor the colonization pattern of the gfp-labeled derivative strain of Pseudomonas putida ATCC 17514 on fluorene and phenanthrene crystals. The in situ experiments showed that P. putida tends to grow directly on phenanthrene, forming a biofilm on accessible crystalline surfaces. On the other hand, no significant biofilm formation was observed in the presence of fluorene. The results obtained showed that substrate properties affected bacterial strategy regarding uptake.

Biofilms↗

PubMed2003

Effect of diclofenac sodium on the healing process of end-to-end anastomosis in carotid arteries of rabbits. Histopathological and biomechanical studies.

AIM: Diclofenac sodium is a non-steroidal anti-inflammatory drug commonly used to attenuate painful inflammatory reactions in surgery. However, it may delay healing in the skin and gastrointestinal tract. The aim of this study was to evaluate the influence of Diclofenac in vascular healing. METHODS: Ninety rabbits had their carotid arteries sectioned and reconstructed by end-to-end anastomosis with interrupted sutures. The animals were randomly allocated into 3 groups of 30 each and treated by intramuscular route with saline (control), 5 mg/kg/day of diclofenac sodium (DS-5), and 10 mg/kg/day of diclofenac sodium (DS-10). Treatment began on the day of surgery and lasted 4 days. Angiography, biomechanical properties (failure load, failure elongation, yield point, yield point elongation, and stiffness were obtained from the load/elongation curve), macroscopic and histological examinations (hematoxylin-eosin, Masson, Calleja, Picrossirius-red), and scanning electron microscopy were studied in both arteries on the 3rd and 15th postoperative days. RESULTS: No significant differences in biomechanical properties were observed either in the 3 groups or the experimental times. The carotid artery healing process was similar in the 3 groups. CONCLUSION: Diclofenac sodium did not cause alterations nor delayed carotid artery healing.

Anastomosis, Surgical↗

PubMed2002

Performance of partially separate sewer systems and impacts on receiving waters.

The aim of this document is to present and discuss the results of the experimental work undertaken in Laje stream, in a section near the village of Oeiras in Portugal. The work was developed with the main objective of characterising stormwater quality in Portuguese drainage systems, and to predict the effects of the performance of partially separate sewer systems on receiving waters. For this purpose, volume and characteristics of stormwater carried by a partially separated sewer system were estimated, both in terms of flow and Chemical Oxygen Demand (COD) loads. The study also analyses the eventual implementation of non-conventional solutions, as a way of reducing problems of bacteriological contamination of seawaters. This aspect is particularly important in Portugal, where the population is mainly concentrated in urban areas located down-stream of important drainage basins, close to the coastline. Therefore, sanitary sewer overflows discharging directly into receiving waters are frequent, with possible consequences in terms of bacteriological contamination of bathing areas. Based on experimental research and available data it was possible to collect informations regarding stormwater average COD and overflow coliform loads, and the occurrence of first flush effects.

Cities↗

PubMed2001

Noninvasive diagnosis of allograft vascular disease after heart transplantation.

OBJECTIVE: To determine the predictive values of noninvasive tests for the detection of allograft vascular disease. METHODS: We studied 39 patients with mean ages of 48+/-13 years and a follow-up period of 86+/-13 months. The diagnosis of allograft vascular disease was made by cine-coronary arteriography, and it was considered as positive if lesions existed that caused > or =50% obstruction of the lumen. Patients underwent 24h Holter monitoring, thallium scintigraphy, a treadmill stress test, and dobutamine stress echocardiography. Sensitivity, specificity, and positive and negative predictive values were determined in percentages for each method, as compared with the cine-coronary arteriography results. RESULTS: Allograft vascular disease was found in 15 (38%) patients. The Holter test showed 15.4% sensitivity, 95.5% specificity. For the treadmill stress test, sensitivity was 10%, specificity was 100%. When thallium scintigraphy was used, sensitivity was 40%, specificity 95.8%. On echocardiography with dobutamine, we found a 63.6% sensitivity, 91.3% specificity. When the dobutamine echocardiogram was associated with scintigraphy, sensitivity was 71.4%, specificity was 87%. CONCLUSION: In this group of patients, the combination of two noninvasive methods (dobutamine echocardiography and thallium scintigraphy) may be a good alternative for the detection of allograft vascular disease in asymptomatic patients with normal ventricular function.

Adult↗

PubMed2000

Saccharomyces boulardii stimulates sIgA production and the phagocytic system of gnotobiotic mice.

The effect of Saccharomyces boulardii on the immune system was evaluated, comparing germ-free Swiss/NIH mice monoassociated with the probiotic with germ-free mice. Saccharomyces boulardii colonized the gut of germ-free mice and survived the gastrointestinal conditions. An increase in sIgA production, both total and anti-S. boulardii, was observed in the intestinal contents of monoassociated mice when compared with germ-free controls. The number of Kupffer cells was significantly higher in monoassociated mice than in germ-free controls. In S. boulardii-monoassociated mice, clearance of Escherichia coli B41 was higher than in germ-free controls. TNF-alpha, IFN-gamma and IL-12 serum levels were higher at earlier time points in monoassociated mice when compared with germ-free mice. These results show that the yeast S. boulardii modulates the host immune responses. This effect may be of interest for improving the resistance to enteropathogenic bacterial infections.

Animals↗

PubMed1996

Abnormal systolic intraventricular flow velocities after valve replacement for aortic stenosis. Mechanisms, predictive factors, and prognostic significance.

BACKGROUND: Dynamic intraventricular flow velocities after valve replacement for aortic stenosis have been associated with high in-hospital morbidity and mortality. The aims of the present study were to determine the mechanisms and preoperative predictors of abnormal flow velocity (AFV) after valve replacement for aortic stenosis and to assess the clinical course of patients with AFV after surgery. METHODS AND RESULTS: One hundred consecutive patients with pure aortic stenosis were studied prospectively before operation by cardiac catheterization and Doppler echocardiography. After surgery, intraventricular flow was studied by Doppler echocardiography at rest, during nipride infusion, and during dobutamine infusion. AFV (defined as a systolic dagger-shaped Doppler spectrum > 2 m/s) occurred in 14 patients at rest and in 27 patients during nipride and/or dobutamine infusion. In most patients, AFV was associated with left ventricular cavity squeezing. Left ventricular end-diastolic diameter, preoperative intraventricular flow velocity and septal-to-posterior wall thickness ratio by Doppler echocardiography, and mean transvalvular pressure gradient and ejection fraction by catheterization emerged as predictors of resting postoperative AFV. Patients with resting AFV had a higher incidence of dyspnea or hypotension (64% versus 21%, P < .01) and a longer hospital stay (13.1 +/- 5.8 versus 11.1 +/- 2.5, P < .05) than patients without AFV. In contrast, at a 1-year follow-up, no patient with resting AFV died. CONCLUSIONS: First, AFV occurs in 14% of patients at rest after valve replacement for aortic stenosis and can be provoked or worsened by ventricular unloading or inotropic stimulation. Second, AFV is related more frequently to cavity squeezing than to systolic anterior motion of the mitral valve apparatus. Third, a typical pattern (small, hyperdynamic, and asymmetrically hypertrophied ventricle) is predictive for postoperative AFV and should be taken into account for the postoperative management. Finally, the presence of AFV at rest is associated with high in-hospital morbidity but good long-term prognosis.

Adult↗

PubMed1996

Dobutamine-induced wall motion abnormalities: correlations with myocardial fractional flow reserve and quantitative coronary angiography.

OBJECTIVES: This study evaluated both the relation between dobutamine-induced wall motion abnormalities and the physiologic and morphologic features of epicardial coronary artery stenoses and the impact of the extent of the area at risk on the sensitivity of dobutamine echocardiography. BACKGROUND: The accuracy of dobutamine echocardiography has traditionally been assessed by comparing results with stenosis geometry. Myocardial fractional flow reserve is a functional index of coronary stenosis severity that takes into account both antero-grade and collateral flow and may therefore be a more appropriate standard for comparison. METHODS: Seventy-five patients with normal left ventricular function, good echocardiographic images and an isolated coronary stenosis underwent, within 6 h, dobutamine echocardiography, quantitative coronary angiography and intracoronary pressure measurements. Myocardial fractional flow reserve was calculated as the ratio of mean hyperemic distal coronary to aortic pressure. RESULTS: The degree of dobutamine-induced dyssynergy correlated significantly with percent diameter stenosis (r = 0.68), area stenosis (r = 0.68) and minimal lumen diameter (r = -0.60) and markedly better with myocardial fractional flow reserve (r = -0.77). However, marked dispersion of the individual data was observed. The sensitivity of dobutamine echocardiography in detecting lesions with a minimal lumen diameter < or = 1 mm and diameter stenosis > or = 50% was 83% and 80%, respectively. All but one patient with a myocardial fractional flow reserve >0.75 had a normal stress test result. Among patients with a myocardial fractional flow reserve < or = 0.75, the sensitivity of dobutamine echocardiography was significantly lower for lesions in vessels with a reference diameter < or = 2.6 mm than for lesions in larger vessels (58% vs. 90%, p = 0.008). CONCLUSIONS: 1) The magnitude of wall motion abnormalities induced by dobutamine infusion correlates with angiographic and, more closely, with functional indexes of stenosis severity, even though a wide scatter is observed. 2) In patients with a functionally significant stenosis, the amount of myocardium at risk is a critical determinant of the accuracy of dobutamine echocardiography.

Coronary Angiography↗

PubMed1996

Effect of Saccharomyces boulardii against experimental oral infection with Salmonella typhimurium and Shigella flexneri in conventional and gnotobiotic mice.

Saccharomyces boulardii was shown to be capable of inhibiting multiplication of enteropathogenic bacteria in vitro and is currently used for its anti-diarrhoea properties. We studied the capacity of this yeast to antagonize Salmonella typhimurium and Shigella flexneri in the intestinal tract of conventional or gnotobiotic NMRI mice. Conventional animals were given daily 10 mg doses of S. boulardii, whereas germ-free animals were given a single 10 mg dose. Both groups were challenged orally 5 d later with the pathogenic bacteria (10(8) or 10(2) viable cells, respectively). Control groups were treated with saline instead of S. boulardii. Mortality and/or histopathological data showed a protective effect against the pathogenic bacteria in yeast-treated mice. Saccharomyces boulardii colonized the digestive tract of gnotobiotic mice and the number of viable cells ranged around 10(10) g-1 of faeces. In experimental and control gnotobiotic animals, Salm. typhimurium and Sh. flexneri became rapidly established at a level of about 10(10) viable cells g-1 of faeces and remained at high levels until the animals died or were sacrificed. The protection against Salm. typhimurium and Sh. flexneri obtained in conventional and/or gnotobiotic mice previously associated with S. boulardii is not due to the reduction of the bacterial populations in the intestines.

Administration, Oral↗

PubMed1995

Accuracy of aortic stenosis severity assessment by Doppler echocardiography: importance of image quality.

UNLABELLED: The aim of the present study was to investigate which factors could influence the accuracy of aortic stenosis severity assessment by Doppler echocardiography in an unselected population. Doppler echocardiographic determination of mean transvalvular pressure gradient and aortic valve area by continuity equation was performed in 101 patients before catheterization. According to the catheterization data, aortic stenosis was classified into 2 categories: mild to moderate (orifice area [Gorlin formula] > 0.75 cm2, mean transvalvular gradient < 50 mmHg) and severe (orifice area < or = 0.75 cm2, mean transvalvular gradient > or = 50 mmHg). The influence of eight factors on the absolute difference in aortic valve area and mean transvalvular pressure gradient and on the concordant classification in the same category by both methods was investigated. RESULTS: By multivariate analysis, the absolute difference in aortic valve area by both methods was significantly associated with poor image quality, absolute difference between mean catheterization and Doppler transvalvular gradient and inversely related to body mass index. Absolute difference in mean transvalvular gradients by both methods was significantly associated only with image quality. Poor image quality emerged as the only significant factor influencing the concordant classification between invasive and noninvasive studies according to orifice area (but not according to transvalvular pressure gradient). CONCLUSION: Echographic image quality significantly influences the accuracy of Doppler echocardiographic determination of aortic valve area and, to a lesser extent, of transvalvular pressure gradient. Therefore, the mere noninvasive approach is not suitable to every consecutive patient with aortic stenosis. Qualifications concerning overall image quality should identify patients most likely to benefit from catheterization.

Adolescent↗