A semiautomated objective technique for applying the proximal isovelocity surface area method to quantitate mitral regurgitation: Clinical studies with the digital flow map

BACKGROUND: Clinical application of the color Doppler proximal isovelocity surface area (PISA) method to quantify mitral regurgitation (MR) has been limited by the often inaccurate assumption that isovelocity surfaces are hemispheric. This study applied an objective method for selecting the region where the hemispheric geometry holds best on the basis of mathematic analysis of results at different distances from the orifice. We aimed to demonstrate this approach can be applied accurately in the clinical setting and can be semiautomated to promote routine use by extracting velocities from the digital Doppler output and then performing all the calculations automatically. METHODS: In 75 patients with isolated MR, centerline velocities (V(r)) at each distance (r) from the orifice in the proximal flow field were extracted digitally. The automated analysis calculated peak MR flow rates as 2pir(2)V(r) and plotted these against their respective velocities. The optimal value for peak flow rate was obtained mathematically at the site where the slope of this curve was minimal (least inaccuracy). This value was combined with continuous wave Doppler data to provide regurgitant stroke volume (RSV) and orifice area (ROA), which were compared with quantitative Doppler in 75 patients and angiography in 42. RESULTS: RSV and ROA by this optimized, semiautomated PISA method correlated and agreed well with values from quantitative Doppler (y = 0.9x + 1.9, r = 0.90, standard error of the estimate [SEE] = 8.1 mL, mean difference = -0.7 +/- 8.5 mL for RSV; y = 0.9x + 0.02, r = 0.90, SEE = 0.048 cm(2), mean difference = -0.005 +/- 0.1 cm(2) for ROA) and correlated well with angiography (rho = 0.90 for both RSV and ROA). CONCLUSIONS: This objective PISA method for quantifying MR is accurate in the clinical setting and has been semiautomated by use of analysis of digital velocity data to provide a rapid and practical technique suitable to facilitate more extensive application in routine practice.     

Usefulness of three-dimensionally guided assessment of mitral stenosis using matrix-array ultrasound

Two-dimensional (2-D) planimetry is limited by the technical demands, time, and observer variability required to locate the minimal orifice area, limiting the confident clinical reporting of mitral valve area (MVA). In 27 consecutive patients, MVA was determined independently by 2 observers using the conventional 2-D method and a new 3-D-guided method. Using a matrix-array probe, the valve was visualized in a long-axis view and a cursor steered to intersect the leaflet tips and provide a perpendicular short-axis plane viewed side-by-side. Two-dimensional and 3-D-guided methods allowed planimetry in 24 patients. Consistent with better orifice localization, 3-D guidance eliminated the overestimation of internal orifice diameters in the planimetered short-axis view relative to the limiting diameter defined by the long-axis view (for 3-D guidance, 0.73 +/- 0.20 vs 0.73 +/- 0.21 cm, p = 0.98, vs 0.90 +/- 0.27 cm in the 2-D short-axis view, p <0.01). Accordingly, mean values for the smallest orifice area by 3-D guidance were less than by 2-D imaging (1.4 +/- 0.5 vs 1.5 +/- 0.5 cm(2), p <0.01), changing the clinical severity classification in 11 of 24 patients (46%). The 2-D method also overestimated MVA relative to 3-D guidance compared with Doppler pressure halftime and (n = 6) Gorlin areas. Phantom studies verified no differences in resolution for the 2 acquisition modes. Three-dimensional guidance reduced intraobserver variability from 9.8% to 3.8% (SEE 0.14 to 0.06 cm(2), p <0.01) and interobserver variability from 10.6% to 6.1% (SEE 0.15 to 0.09 cm(2), p <0.02). In conclusion, matrix-array technology provides a feasible and highly reproducible direct 3-D-guided method for measuring the limiting mitral orifice area.     

Impact of tissue harmonic imaging in patients with distorted left ventricles: improvement in accuracy and reproducibility of visual, manual and automated echocardiographic assessment of left ventricular ejection fraction.

AIMS: The aim of this study was to assess the incremental value of tissue harmonic imaging vs conventional echocardiography for evaluating left ventricular ejection fraction by manual and automated quantitation as well as visual estimation in patients with distorted left ventricles. METHODS AND RESULTS: In 25 patients unselected for image quality and with distorted left ventricles who underwent a nuclear study, digital cineloops of standard apical views were acquired by both tissue harmonic imaging and conventional echocardiography and sent to six observers for analysis of visual and quantitative left ventricular ejection fraction. Tissue harmonic imaging improved both the correlation and agreement of all echo techniques with nuclear measures, compared with conventional echocardiography echo, reducing standard errors (SE) to below 10%: for the visual estimate SE=7.5%, for manual tracing SE=6.3% and for automated tracing SE=8%. Tissue harmonic imaging decreased inter-observer variability compared with conventional echocardiography echo for both visual assessment (12.4% vs 18.4%, P<0.05) and quantitative measures (for manual tracing, 8.2% vs 11.8%, P<0.05; for automated tracing, 7.8% vs 16.8%, P<0.05). CONCLUSIONS: In patients with distorted left ventricles unselected for image quality, tissue harmonic imaging improves accuracy and reproducibility of both visual and quantitative echocardiographic assessment of left ventricular ejection fraction. In particular, it promotes automated quantitation by reducing its high standard error into a clinically reasonable range.     

Sediment Metal Contamination in the Kafue River of Zambia and Ecological Risk Assessment

Zambia’s Kafue River receives wastes from various sources, resulting in metal pollution. This study determined the degree of contamination of 13 metals (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg and Pb) in Kafue River sediment and the associated ecological risks at six sites in three different seasons. The level of contamination for most metals showed significant site and seasonal differences. The contamination factor and pollution load index indicated that concentrations of most metals particularly copper (Cu), cobalt (Co), manganese (Mn) and arsenic (As) were very high at sites within the Copperbelt mining area. The geoaccumulation index showed an absence of anthropogenic enrichment with Cd and Hg at all the study sites and extreme anthropogenic enrichment with Cu at sites in the Copperbelt mining area. Potential ecological risk showed that Cu and As were likely to cause adverse biological effects to aquatic organisms in the Copperbelt mining region of the Kafue River.     

Acute non-A,non-B hepatitis in Italy: A 16-year prospective epidemiological study. The possible role of hepatitis C virus

Summary During a survey of acute symptomatic viral hepatitis conducted in Padua over the last 16 years, 404 (20%) cases of non-A, non-B hepatitis were observed, including 55% with overt parenteral exposure (35% drug abusers) and 45% with unknown exposure. Between 1978 and 1982 the attack rate of the disease increased significantly (p < 0.01) in males, (from 3.8 to 17.3/10⁵ inhabitants), in adolescents and in youths. The prevalence of drug abusers rose up to 58% in 1982 suggesting the occurrence of an outbreak in this risk group. In subsequent years the attack rate returned to initial levels in males, although drug abuse still remains the single most important route of infection, and declined in females, especially after the disappearance of post-transfusion hepatitis since 1991. Retrospective anti-HCV testing of patients seen up to 1990 and prospective investigation of patients hospitalized later have shown an antibody prevalence of 88% among parenterally transmitted cases, and of 29% in the other patients, without significant differences between the prospective and the retrospective study. These findings suggest that an outbreak of hepatitis C occurred in our area in the early eighties and that drug abuse is still the most important mode of transmission of acute hepatitis C.

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Akute Hepatitis Non-A, Non-B in Italien: Prospektive epidemiologische Studie über 16 Jahre. Die mögliche Bedeutung des Hepatitis C Virus

Zusammenfassung In Padua wurde während der vergangenen 16 Jahre eine Überwachungsstudie zur akuten, symptomatischen Virushepatitis durchgeführt. Dabei fanden sich 404 (20%) Fälle von Non-A-, Non-B-Hepatitis, einschließlich 55% mit offensichtlicher parenteraler Exposition (35% Drogenabhängige) und 45% mit unbekannter Exposition. Von 1978 bis 1982 war eine signifikante Zunahme der Fälle (p < 0,01) bei männlichen Adoleszenten und Jugendlichen (von 3,8 auf 17,3/10⁵ Einwohner) zu beobachten. 1982 stieg der Anteil der Drogenabhängigen auf bis zu 58% an. Dies läßt auf einen Ausbruch in dieser Risikogruppe schließen. In den folgenden Jahren kehrte die Infektionsrate bei Männern auf die ursprüngliche Höhe zurück. Drogenabusus ist jedoch nach wie vor die wichtigste Infektionsdeterminante. Die Infektionsrate hat bei Frauen, vor allem nach Verschwinden der Posttransfusionshepatitis, seit 1991 abgenommen. Eine nachträgliche Testung der bis 1990 beobachteten Fälle auf anti-HCV und die prospektive Untersuchung der danach stationär aufgenommenen Patienten ließ bei parenteral infizierten Fällen eine Antikörperprävalenz von 88% erkennen. Von den anderen Patienten waren 29% anti-HCV positiv. Zwischen den retrospektiv und prospektiv untersuchten Fallgruppen ergaben sich keine signifikanten Unterschiede. Die Befunde lassen auf eine Hepatitis C-Epidemie in den frühen 80er Jahren in unserer Gegend schließen. Es ist anzunehmen, daß Drogenmißbrauch noch immer der wichtigste Übertragungsmodus für die akute Hepatitis C ist.

     

Routine use of fluconazole prophylaxis in a neonatal intensive care unit does not select natively fluconazole-resistant Candida subspecies

BACKGROUND: We have previously demonstrated efficacy against fungal colonization and infection of fluconazole prophylaxis that was routinely administered since 2001 in our ICU for preterm infants <1500 g at birth (VLBW). With prolonged use, concerns exist for the emergence of acquired fungal resistance and of Candida subspecies that are natively fluconazole-resistant (NFR), mostly Candida glabrata and Candida krusei. METHODS: We evaluated retrospectively all clinical and surveillance fungal isolates obtained from VLBW infants in our NICU during a 10-year period (1997-2006). Each fungal isolate was speciated, infants colonized or infected with NFR-Candida spp were identified and the incidence rates of colonization and infection by these fungal species were calculated. A comparison was made of the 6-year (2001-2006) prophylaxis period with the 4-year (1997-2000) preprophylaxis period. RESULTS: Overall, colonization by NFR-Candida spp ranged between 2.8% and 6.6% of VLBW infants yearly admitted, without any increasing trend during the study period. There were 18 of 434 (4.1%) neonates colonized by these species. Five episodes of systemic fungal infections caused by NFR-Candida spp occurred (incidence rate, 1.1%). No significant differences were detected when compared with the preprophylaxis period, when 11 of 295 infants (3.7%) were colonized by NFR-Candida spp and 4 episodes of infection occurred (1.4%) (P = 0.84 and 0.76, respectively). CONCLUSIONS: Fluconazole prophylaxis administered to VLBW neonates in 4- to 6-week courses after birth does not lead to the emergence of natively fluconazole-resistant Candida spp.