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  • 1
    Electronic Resource
    Electronic Resource
    Local Repolarization Abnormalities Induced by Transcatheter Radiofrequency Ablation in Pigs (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 20 (1997), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Radiofrequency (RF) ablation alters action potential repolarization of myocardial cells and, theoretically, tbis should induce ST-T segment changes in the ECG. Since these ECG abnormalities have been rarely reported in patients submitted to RF ablation we assess the ability of the procedure to caase ST-T segment changes in local electrograms. Epicardial ECG mapping was performed in 17 anesthetized open chest pigs submitted to endocardial (n = 9) or to epicardial (n = 8) unipolar radiofrequency ablation (500 kHz, 20 W for 5-10 s). To characterize the cellular electrophysiological alterations induced by RE ablation transmembrane action potentials were recorded at various distances from the ablation lesion; these were compared with seven control pigs. Endocardial RE ablation induced a transient (〈 5 min) change of 6.1 ± 2.4 m V in T wave amplitude (baseline: 12.8 ± 5.6 mV, P 〈 O.OOl) in 141 out of 269 epicardial electrodes. T wave changes were associated with shortening in local activation time (20.1 ± 2.3 ms at baseline vs 18.5 ± 2.5 ms at 60 s after ablation, P = 0.03). RE current caused persistent ST segment elevation at the center of the ablation lesion with no transmural expansion. Intracellular potentials along a 2-6-mm wide myocardial band bordering the RE lesion showed lower amplitude (101 ± 7.0 mV vs 71 ± 23 mV, P 〈 0.01) and shorter duration (254 ± 44 ms vs 156 ± 29 ms, P 〈 0.01) than control hearts. The center of the ablation lesion was electrically anexcitable. We concluded that RF ablation alters cellular electrophysiology in small areas surrounding the ablation lesion and this causes short-lasting transmural changes in T wave amplitude and nontransmural ST segment elevation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1997.tb03601.x
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  • 2
    Electronic Resource
    Electronic Resource
    Five French versus eight French catheters and the Judkins technique (1988)
    Springer
    The international journal of cardiovascular imaging 3 (1988), S. 61-65 
    Details
    ISSN: 1573-0743
    Keywords: coronary artery disease ; angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to compare 5 French versus 8 French catheters for assessing ischemic heart disease, we prospectively studied 2 groups of 100 patients each, one with 5 French (group I) and the other with 8 French (group II) catheters by the Judkins technique. Significant differences were found in the greater easiness to catheterize LV (p〈0.05) and LCA (p=0.01) in group II and in better quality image for LCA in group II (p〈0.05), although all patients in both groups had acceptable image quality. Pressure curves quality was better in group II (p〈0.01); X-ray exposure time was longer in group I (p〈0.001) and arterial compression time in group II (p〈0.0001). Group I showed 3 and group II 10 mild hematomas (p〈0.05). The procedure could be completed by the elected first artery and type of catheter in 95 patients in group I and in 96 in group II. Thus, the Judkins technique with 5 French catheters is as valid as with 8 French for assessing ischemic patients, reducing arterial morbidity, although mildly increasing technical difficulty and mildly decreasing quality image.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01801646
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  • 3
    Electronic Resource
    Electronic Resource
    Agricultural use of sewage sludge and its regulation (1995)
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 173-177 
    Details
    ISSN: 1573-0867
    Keywords: sewage sludge ; organic matter ; heavy metals ; legislation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sewage sludge is waste for which the most positive outlet must be sought whilst, at the same time, making use of its qualities. In view of its organic matter and other nutrients content, it may be thought that the best system is to use it for agricultural purposes, although the load of heavy metals it may bear with it proves to be the main obstacle involved. Since it is a heterogeneous material whose composition depends on various factors, the content of such metals in sewage sludge will be highly variable. Thus it becomes necessary to always analyze sewage sludge before directing it towards agricultural use and also to know the heavy metal content of the soil where it is applied already so as to adjust this agronomical practice to the limits as set by current legislation in force. The provisions of law must also be complied with when certain substances deemed toxic or dangerous are present in sewage sludge. The purpose of all this is to prevent possible soil pollution and other kinds of risk involved in accumulation in the food chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00747698
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  • 4
    Electronic Resource
    Electronic Resource
    Myocardial segment shrinkage during coronary reperfusion in situ (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 519-526 
    Details
    ISSN: 1432-2013
    Keywords: Myocardial infarction ; Ischaemia ; Functional studies ; Reperfusion ; Hypercontracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have investigated the changes in myocardial segment length induced by reperfusion, and their relation to myocyte hypercontracture and contraction band necrosis. Regional wall function was monitored by ultrasonic gauges in 39 pigs submitted to 48-min occlusion of the left anterior descending coronary artery (LAD) and 6 h of reperfusion. Infarct size (triphenyltetrazolium reaction), the extent of contraction band necrosis (quantitative histology) and myocardial water content (desiccation) were measured. Reperfusion induced a marked reduction in end-diastolic length of the LAD segment in all animals, maximal within 15 min after reflow. After 30 min of reperfusion, end-diastolic length of the LAD segment remained below the basal value in 15 animals. The 15 animals that showed shrinkage of the reperfused segment did not differ from the remaining animals in heart rate, aortic pressure, or control segment variables, but had larger infarcts (mean ± SEM: 32.1 ± 5.4 vs 12.1 ± 3.2% of the area at risk,P = 0.003). There was an inverse correlation between end-diastolic length of the LAD segment after 30 min of reperfusion and infarct percentage (r = -0.72) or the extent of contraction band necrosis (r = -0.71). End-diastolic length reduction was more pronounced in larger infarcts despite a more severe myocardial oedema. Neither systolic shortening of the LAD segment nor end-diastolic length or systolic shortening of the control segment, or haemodynamic variables after 30 min of reperfusion correlated to infarct percentage or to the extent of contraction band necrosis. It is concluded that myocardial segment shrinkage during reperfusion reflects myocyte hypercontracture leading to contraction band necrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02191898
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  • 5
    Electronic Resource
    Electronic Resource
    Intimal injury in a transiently occluded coronary artery increases myocardial necrosis. Effect of aspirin (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 663-670 
    Details
    ISSN: 1432-2013
    Keywords: Key words Myocardial reperfusion ; Platelets ; Endothelial injury ; Microembolization ; Leucocytes ; Reactive hyperaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study tested the hypothesis that intimal injury in a transiently occluded coronary artery limits myocardial salvage. The effect of intimal injury on reactive hyperaemia was investigated in 17 pigs submitted to a 30-min occlusion of the left anterior descending coronary artery (LAD), not resulting in myocardial infarction. Catheter-induced intimal damage increased local platelet deposition (99mTc) and reduced hyperaemia, but did not modify myocardial platelet or polymorphonuclear leucocyte content (myeloperoxidase activity) after 6 h reperfusion. To investigate the influence of intimal injury on the extent of myocardial necrosis secondary to a more prolonged coronary occlusion, and the role of platelets on this influence, 52 pigs were submitted to a double randomization (2×2 factorial design) to 250 mg i.v. aspirin vs. placebo and to coronary intimal injury vs. no coronary damage before a 48-min occlusion of the LAD and 6 h of reperfusion. After excluding 12 animals with reocclusion, coronary intimal injury was associated with larger infarcts (triphenyltetrazolium reaction) in animals receiving placebo (36.2±7.0% of the area at risk in animals with intimal injury vs. 10.8±3.9% in animals without coronary injury, P=0.006) but not in those receiving aspirin (20.3±6.5 vs. 21.7±6.5% of the area at risk in animals with and without intimal injury respectively). These results suggest that coronary intimal injury in the reperfused artery may have adverse effects on myocardial salvage by mechanisms other than reocclusion or embolization of platelet aggregates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050183
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  • 6
    Electronic Resource
    Electronic Resource
    Contraction band necrosis at the lateral borders of the area at risk in reperfused infarcts (1995)
    Springer
    Virchows Archiv 426 (1995), S. 393-399 
    Details
    ISSN: 1432-2307
    Keywords: Myocardium ; Ischaemia ; Reperfusion injury ; Contraction band necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to test the hypothesis that increased mechanical stress at the lateral borders of the area at risk may render this area more susceptible to ischaemia/reperfusion injury in the absence of collateral flow. The spatial distribution of myocardial necrosis within the territory of a transiently occluded left anterior descending coronary artery was investigated in 31 porcine hearts submitted to 48 min of coronary occlusion and 6 h of reperfusion. Immediately before excising the heart, the left anterior descending coronary artery was re-occluded and 10% fluorescein was injected in the left atrium. The area at risk was imaged by ultraviolet illumination of the myocardial slices, and the area of necrosis by incubation in triphenyltetrazolium chloride. The area at risk was divided in four sectors and an index of eccentricity was calculated as the percent of the area of necrosis located in the two lateral sectors of the area at risk. The area of contraction band necrosis was measured in whole heart histological sections. Infarcts were generally small, and were composed almost exclusively of contraction band necrosis. There was a good correlation between the extent of the area of contraction band necrosis and infarct size (r=0.831, P〈0.0005). The area of necrosis had a patchy appearance and was predominantly distributed along the lateral borders of the area at risk. This eccentric distribution was more prominent in smaller infarcts, and the eccentricity index was inversely correlated with infarct size (r=−0.471, P=0.007), suggesting that contraction band necrosis occurres first at the interface between control and reperfused myocardium in this model. These results are in agreement with a prominet role of mechanical factors in the genesis of myocardial necrosis during transient coronary occlusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191349
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  • 7
    Electronic Resource
    Electronic Resource
    Direct non-invasive techniques for assessing coronary bypass graft patency (1985)
    Springer
    The international journal of cardiovascular imaging 1 (1985), S. 181-188 
    Details
    ISSN: 1573-0743
    Keywords: computed tomography ; venous DSA ; coronary bypass grafts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Venous digital subtraction angiography (vDSA) and computed tomography (CT) are two non-invasive techniques that allow direct imaging of coronary grafts. Neither of them is 100% accurate when compared to selective angiography. We studied 52 patients with 107 coronary grafts (101 saphenous and 6 mammary artery grafts) by CT and vDSA. Fifty patients had control selective angiography and 2 had control digital arterial aortography. CT correctly diagnosed 88 of the 95 patent grafts and 8 out of the 12 occluded grafts (in 1 patient 3 patent grafts could not be well analyzed owing to artifacts from pacemaker wires). vDSA correctly identified 93 patent grafts and the 12 occluded grafts, allowing the correct diagnosis of the 11 non/or misdiagnosed CT grafts. CT allowed the correct identification of ihe 2 misdiagnosed vDSA grafts. These results show that when there was agreement between CT and vDSA there were no diagnostic errors and that the combination of these two non-invasive techniques may avoid selective angiography for studying coronary bypass graft patency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01784204
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