Ambient Fluid Velocity Influences Proximal Isovelocity Surface Area Calculations

Background: Recent reports have described a simplified mass balance equation designed to predict volumetric flow rate through regurgitant and shunt orifices. The proximal isovelocity surface area (PISA) technique relies on the assumption that constant velocity surfaces (isovels) that are hemispheric in shape can be constructed proximal to the orifice, and flow passing through these surfaces must also pass through the orifice by conservation of mass. The method has been validated in simplified in vitro models, but these models have been symmetric in design and do not consist of ambient crossflows that are found in the beating heart. This study addressed the hypothesis that ambient crossflow will affect the validity of the PISA method. Methods and Results: An in vitro model was designed to test the effect of crossflowing streams on the PISA calculation while maintaining control of volumetric flow through the orifice. PISA predicted flows showed a good correlation but overestimated actual flows by 10%–110% (Y = 2.16X-118, r = 0.96). Addition of low flow data slightly reduced the overestimation (Y = 1.89X-55.2, r = 0.97). Only under high output state conditions (high orifice and crossing flows) was good agreement found (Y = 0.92X + 9.78, r = 0.95). Conclusions: The presence of crossflowing streams in the vicinity of PISA images will distort the converging flow and its image in such a way that the simplified PISA theory may correlate with true flow but only rarely produces true agreement. Only when competing factors fortuitously cancel does the PISA method appear to be accurate. Since PISA images are readily obtained in patients and since the method has received extensive attention in the literature, systematic derivation of correction factors accounting for crossflow is indicated. In the meantime, caution should be exercised when interpreting PISA images in the presence of crossflowing streams .     

Patterns of referral for children with speech disorders

This paper presents information about a sample of 200 children aged 3-6 years in four Health Authorities. They were referred routinely for speech therapy. Age of referral, distribution within the family, sex and sources of referral are indicated and discussed.     

Medical treatment of myocardial ischemia in coronary artery disease: effect of drug regime and irregular dosing in the CAPE II trial

OBJECTIVES: The Circadian Anti-ischemia Program in Europe (CAPE II) compared the efficacy of amlodipine and diltiazem (Adizem XL) and the combination of amlodipine/atenolol and diltiazem (Adizem XL)/isosorbide 5-mononitrate on exercise and ambulatory myocardial ischemia during regular therapy and after omission of medication. BACKGROUND: The optimal medical therapy for ischemia suppression and the impact of irregular dosing using agents with different pharmacologic properties has not been established in patients with coronary disease. METHODS: Patients with > or = 4 ischemic episodes or > or = 20 min of ST segment depression on 72-h electrocardiogram were randomized to amlodipine 10 mg once daily or diltiazem (Adizem XL) 300 mg once daily in a 14-week double-blind randomized multicountry study. In the second phase, atenolol 100 mg was added to amlodipine and isosorbide 5-mononitrate 100 mg to diltiazem (Adizem XL). Ambulatory monitoring (72 h) and exercise testing were repeated after both phases, on treatment and after a 24-h drug-free interval. RESULTS: Both monotherapy with amlodipine and diltiazem (Adizem XL) were effective on symptoms and ambulatory and exercise ischemia. Combination therapy reduced ischemia further, with amlodipine/atenolol superior to diltiazem (Adizem XL)/isosorbide 5-mononitrate. Amlodipine/atenolol was significantly superior during the drug-free interval with maintenance of ischemia reduction. CONCLUSIONS: Amlodipine, with its intrinsically long half-life alone or together with beta-blocker, is likely to produce superior ischemia reduction in clinical practice when patients frequently forget to take medication or dose irregularly.     

Growth charts: help or hindrance?

The use of growth charts is being promoted world-wide, particularlyby UNICEF, as one of the essential ingredients of any primaryhealth care programme. Though they are being adopted in manycountries, their effectiveness has been evaluated in very few. In this analysis of the effectiveness of the use of growth chartsin Papua New Guinea it is hypothesized that growth charts areused to fulfil four purposes: (a) to assist health workers todiagnose children who are suffering from, or are in danger ofsuffering from, malnutrition; (b) to select those children thatare seriously malnourished and may need referral; (c) to evaluatethe impact of nutrition programmes; and (d) to assist healthworkers to educate mothers about child growth and nutrition.A review of research in Papua New Guinea reveals that growthcharts, as they are being used at present, do not fulfil anyof these purposes. As such, it is questioned whether, consideringthe resources that are necessary to carry Out growth monitoringwith growth charts, it is sensible to continue promoting theiruse.