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Biomedical subjects

I Préda

Publications and source records attributed to I Préda.

12 recordsLinked to original sources

[Clinical value of body surface mapping in the diagnosis of ischemic heart disease].

A series of 137 patients suffered in clinically documented angina pectoris were analyzed by 12-lead exercise ECG, exercise body surface potential mapping and exercise thallium scintigraphic methods and the results were compared to that of selective coronary angiography and left ventriculography. If coronary artery stenosis were considered to be significant in the presence of more than 70% vessel narrowing, the sensitivity figures were 76, 93 and 88% for exercise 12-lead ECG, exercise body surface potential mapping and exercise thallium scintigraphy, respectively. In considering 50% coronary artery narrowing to be significant, the same figures were 78, 94 and 89%. Specificity figures at the same order were 59, 65 and 80% for more than 70%, and 64, 70 and 88% for more than 50% coronary obstructions. Exercise body surface potential mapping and exercise thallium scintigraphy applied parallelly gave a sensitivity of 100% and specificity of 53%. False-negative and false-positive exercise body surface potential mapping and thallium scintigraphic tests were analysed taking into consideration left ventricular function indices and respective patients. The authors suggest that the outstanding high sensitivity of the above mentioned two tests applied parallelly reveals that they highlights partially different aspects of coronary artery disease, and that is why the overlapping between the methods is relatively small. The majority of false-positive tests characterize a pathological state, and in these cases the exact diagnosis should be cleared up by other noninvasive/invasive methods.

Angina Pectoris

Comparative evaluation of the effect of balloon dilatation by exercise precordial mapping and exercise 201-thallium scintigraphy.

Precordial exercise electrocardiographic mapping and exercise 201-thallium scintigraphy were simultaneously used on sixteen patients before, shortly after and three months after percutaneous transluminal coronary angioplasty (PTCA) to evaluate the immediate and late results of the intervention. In spite of the limited number of observations, positive exercise precordial mapping and or a reversible 201-thallium perfusion defect after PTCA seem to be indicative of failure of balloon dilatation or of development of restenosis in a given coronary artery. "Reverse minimum", that is the minimum in the resting precordial map which disappears on exercise, may be a sign of segmental coronary artery occlusion and well functioning collateral supply.

Adult

Surface potential distribution on the human thoracic surface in left bundle branch block.

The sequences of myocardial excitation in the cases of human LBBB have been studied by the surface mapping technique. Analysis of the surface map patterns of 12 subjects has enabled 4 different types to be described. It is suggested that Type I represents a complete LBBB in the presence of an intact right bundle branch, while Types II and III show different degrees of conduction defect in the right bundle branch, too. The left ventricular activation of these 3 types has a similar pathway in phases II and III which is determined by orientation of the main subepicardial muscle layer coursing through the apex and terminating in the anterobasal region. The terminal anterobasal activation in the cases of LBBB has not only theoretical, but clinical significance, since in the presence of anteroseptal myocardial infarction the signs of necrosis must be hidden not in the early, but in the terminal parts of the QRS complex of conventional ECG. The lack of terminal anterior positivity of surface maps in the case of LBBB may be indicative of chronic anterior myocardial infarction.

Bundle-Branch Block

The role of potassium-canrenoate on 3H-noradrenaline uptake and metabolism of the rat heart.

The influence of potassium-canrenoate (structurally related to spironolactones) on noradrenaline (NA) uptake and metabolism of the heart was studied in normal and hypopotassaemic rats. In normal rats spironolactone administration resulted in a marked increase of 3H-NA uptake in both the atrial and the ventricular tissues, but the NA content was unchanged. An increased myocardial NA uptake in the presence of an unchanged content suggested an increased rate of NA turnover under the influence of spironolactone. In saluretic pretreated animals, spironolactone normalized both the previously decreased NA uptake and the low intracellular potassium level of the heart tissue. The augmentation of catecholamine metabolism due to spironolactone may be involved in enhanced activity of adenyl cyclase and forms the basis of the compounds positive inotropic effect.

Animals

Myocardial noradrenaline uptake after coronary occlusion in the rat.

Coronary ligation produced a marked increase in labelled noradrenaline uptake by the myocardial tissue of rats. The peri-ischemic zones showed an elevated accumulation of noradrenaline on the 4th day but the intact zone had returned to normal values. At the 14th day of observation, both the ischemic and per-ischemic tissue exhibited a subnormal accumulation of radioactivity. The role of the acidotic state in the changes of noradrenaline uptake was studied in vitro. Noradrenaline accumulation in the myocardial tissue was higher at pH 6.8 than at 7.4 or 7.1 Competition studies revealed that unlabelled noradrenaline had occupied the binding sites in the same quantity at pH 6.8 and at 7.4. It is assumed that intracellular acidosis was involved in the enhanced accumulation of noradrenaline in the damaged myocardium, and that an increase of noradrenaline concentration in the myocardium may be considered a risk factor in supporting heart function.

Animals