Relationship between micro-invertebrates and macrophytes in a wetland: Laguna Iberá (Corrientes, Argentina). Implications for water quality monitoring.

From November 2000 to September 2001, eight points in the Iberá lagoon were sampled bimonthly. At each point, pH, temperature and dissolved oxygen were measured and invertebrates were collected from the water around macrophytes by mean of a net of 180 mu m pore size. Four biotic indices were calculated and compared, given similar trends. The total number of taxa shows to be a good and simple indicator of water quality. Averaging indices across points we obtained a good positive correlation between indices and temperature. In this ecosystem, multi-habitat sampling must be used in order to obtain a good estimation of ecological integrity. The total number of taxa can be used for water quality assessment.

[Results of coronary surgery in mildly symptomatic patients with left ventricular dysfunction, multivessel disease and stenotic single residual patent vessel]. / Risultati della chirurgia coronarica nei pazienti paucisintomatici con disfunzione ventricolare sinistra, malattia multivasale e unico vaso residuo pervio stenotico.

BACKGROUND: While efficacy of coronary artery bypass surgery in patients with depressed left ventricular function and myocardial ischemia is widely recognized, its results in patients in the absence of clinical evidence of myocardial ischemia remain uncertain. The purpose of this study was to evaluate the effects of coronary revascularization in comparison with conventional medical therapy in subjects with ischemic cardiomyopathy and myocardial ischemia presumed on the basis of angiographic anatomy but not demonstrated by functional testings. METHODS: We selected retrospectively patients who underwent coronary angiography from 1986 trough 1993 and met the following criteria: presence of three-vessel coronary artery disease, occlusion of two and significant luminal narrowing (> or = 50%) of the third major epicardial artery, left ventricular dysfunction (ejection fraction < or = 40%), no angina or presence of mild angina, absence of inducible ischemia on exercise test and, when performed, of redistribution in the vascular territory of the patent vessel. RESULTS: Thirty-one consecutive patients underwent isolated surgical revascularization treatment, while thirty medically treated patients with matched clinical characteristics were selected. Age (61 +/- 10 vs 62 +/- 9), gender (M/F 27/3 vs 24/7), NYHA class I-II (53 vs 62%) or NYHA III-IV (47 vs 38%), incidence of previous infarction (87 vs 94%), number of reversible defects in the vascular territory of the patient vessel on stress scintigraphy (0.6 vs 0.5), patent vessel (right coronary artery 7 vs 10; left circumflex 14 vs 12; left anterior descending 9 vs 9) and left ventricular ejection fraction (28 +/- 8 vs 31 +/- 7), were similar in the two groups (medical vs surgical). Surgically treated patients exhibited a lower proportion of overall cardiac deaths (7/31, 23% vs 19/30, 63%; p < 0.001), and more prolonged survival (67 +/- 9.3 vs 34 +/- 2.5 months; p = 0.04, Mantel and Cox test) than medically treated patients, respectively. The incidence of perioperative myocardial infarction was 10% (3/31). Causes of cardiac death were myocardial ischemia (9/19; 47%), sudden death (5/19; 26%) and heart failure (5/19; 26%) in medical patients, while were surgery (3 cases) and surgery related infection (1 case) (total 4/7; 57%), myocardial ischemia (1/7; 14%), sudden death (1/7; 14%) and heart failure (1/7; 14%) in surgical patients. Cox proportional hazard regression analysis with survival as the dependent variable, identified treatment, surgical or medical, as the best predictor of cardiac events (chi square improvement 9.36, p = 0.002). The next most powerful predictors were NYHA class and ACE-inhibitors treatment (chi square improvement 4.47 and 2.79, respectively). CONCLUSIONS: In patients with left ventricular dysfunction, multivessel coronary artery disease and single patent but stenotic residual vessel, coronary artery bypass grafting appear to offer a better survival than medical therapy, even in the absence of clinically evident myocardial ischemia.

[Comparison of exercise thallium-201 perfusion scintigraphy and coronarography in the prognostic stratification of patients with post-infarction residual ischemia]. / Confronto tra scintigrafia perfusoria con 201-tallio da sforzo e coronarografia nella stratificazione prognostica dei pazienti con ischemia residua post infartuale.

The goals of this study were: 1) to determine and compare the prognostic utility of exercise 201Thallium scintigraphy with coronary angiography in patients with residual ischemia at the symptom limited bicycle exercise testing performed at hospital discharge after a first uncomplicated acute myocardial infarction 2) to verify the ability of perfusion scintigraphy to identify better than coronary angiography a subset of these patients at low risk for future events, despite the ischemic response at the exercise stress testing. Accordingly, follow-up data were obtained prospectively for 72 consecutive patients with adequate left ventricular rest systolic function, and with exercise induced greater than or equal to 1 mm ST-segment depression and/or typical angina pectoris. A planar 201Thallium scintigraphy and coronary angiography were performed within 2 months after acute myocardial infarction. By 31 +/- 29 months 38 patients had no events, while 34 experienced a cardiac event: 3 died of cardiac causes, 2 had nonfatal recurrent myocardial infarction, 29 were rehospitalized for severe class III or IV angina pectoris (4 were treated medically, 25 were revascularized: 20 had coronary bypass surgery, 5 coronary angioplasty). Each of the 3 angiographic classification of coronary artery disease (number of vessels with greater than or equal to 70% reduction of luminal diameter, jeopardy score and Gensini score) accurately identified patients with subsequent cardiac event by Mantel and Cox analysis (respectively p = 0.01, p = 0.0000, p = 0.002). Among 201Thallium variables, the number of segments demonstrating redistribution on delayed images (p = 0.0000), the number of segments with persistent defect (p = 0.0003) and increased 201Thallium uptake by the lungs (p = 0.0100) effectively stratified the probability of survival by the same analysis. Furthermore, the number of perfusion defects, either transient or persistent, with exercise 201Thallium scintigraphy provide additive prognostic information to any of the 3 angiographic coronary artery disease classifications considered. On the contrary, when 201Thallium stress findings are known, coronary angiography data in general are not additive in risk stratification. 17 patients with no reversible perfusion defect remained stable at follow up (52 +/- 28 months) despite development of typical angina pectoris (11/17) and/or ischemic ST segment depression (12/17) during exercise testing.(ABSTRACT TRUNCATED AT 400 WORDS)

[Evaluation of flow reserve in internal mammary artery in situ bypass]. / Valutazione della riserva di flusso dei bypass con arteria mammaria interna in situ.

The internal mammary artery, when used as a conduit for coronary artery bypass, offers a better long-term patency and survival rate than the saphenous vein. However, concern exists that the flow through the internal mammary artery may be inadequate during periods of peak myocardial demand. This flow was investigated in 18 consecutive patients who were selected for coronary bypass of the left anterior descending artery using the internal mammary artery. All patients were evaluated post-operatively within 12 months by means of graded maximal stress test, cardiac catheterization and exercise thallium-201 scintigraphy. Significant improvement in work capacity, maximal rate-pressure product, effort angina and ECG abnormalities during exercise stress testing were observed following internal mammary artery myocardial revascularization. The patency rate for internal mammary artery grafts was 100% (vs 85% for vein grafts); during the followup period, occlusion of a saphenous vein bypass or development of a new stenosis in a native coronary artery was noted in five patients, and two patients were classified as having partial revascularization. Ischemia, demonstrated by perfusion deficits at peak stress which disappeared in the 3-hour delayed film, was documented in 7.4% (4/54) of the areas supplied by internal mammary artery grafts, compared to 31% (13/42) of the regions revascularized using saphenous vein conduits. Although this result was not statistically significant, a definite trend is suggested. We conclude that ischemia demonstrated by stress thallium scintigraphy in the post-operative period is uncommon when an internal mammary artery graft has been used. This suggests that adequate coronary flow exists at peak myocardial demand during exercise.

Positive 131cesium scanning in parathyroid adenoma.

In a case of primary hyperparathyroidism, a palpable nodule, at the base of the right lobe of the thyroid, proved 'cool' during 99mTc scanning, but 'hot' when scanned with radiocesium. The uptake of this tracer was higher than the uptake of 75Seselenomethionine after suppression with T3. The authors discuss the possibility of cases of 'false-positive' radiocesium uptake in extrathyroid nodules, and in particular, the use of this tracer for the detection of parathyroid adenoma by scanning.

Quantitative bone scanning.

The use of a computer coupled on-line with the scintillation camera allows an improvement of the finding of skeletal scintigraphy realized with 99mTc-pyrophosphate, making possible the identification of the smallest bone lesions. It also makes possible the quantification of the uptake degree of the radioindicator demonstrating, in normal subjects, an uptake ratio between the various skeletal segments of 1.07 +/- 0.06. In 44 metastatic lesions the ratio was 1.80 +/- 0.32, whilst in 14 areas of slight hyperfixation of the tracer a value of 1.24 +/- 0.09 was found. Since we were dealing with patients suffering from metastatic bone neoplasms, the authors outline the possibility that the quantification of data will allow the demonstration of the bone metastases even more precociously than with traditional scintigraphix examination.