ELECTROPHYSIOLOGICAL EFFECTS OF VALSALVA MANOEUVER DURING EARLY PREGNANCY IN PATIENTS WITH PAROXYSMS OF ORTHODROMIC ATRIOVENTRICULAR TACHYCARDIA

  Objective: The aim is to study electrophysiological (EPh) indicators of the heart in pregnant women in the first trimester with orthodrome paroxysms of reciprocal atrioventricular tachycardia during the Valsalva test, after a single dose of propafenone and a combination of Valsalva test with propafenone.Methods: Clinical survey, assessment of medical history, physical examination, electrocardiogram (ECG) in 12 leads, Holter ECG monitoring, echocardiography, expert ultrasound examination of the fetus, transesophageal EPh study of the heart, the blood test for electrolytes (potassium, sodium), thyroid hormones (T3, T4, thyroid-stimulating hormone) were included in this study. We examined 28 women during an early gestation.Results: We found that the Valsalva manoeuver, Propanorm, and the combination of the Valsalva manoeuver and Propanorm produced an antiarrhythmic effect through the anterograde and retrograde conduction in reentry.Discussion: The study is the first to reveal that the Valsalva manoeuver influences retrograde conduction in reentry in pregnant patients.Conclusion: We proved that it is necessary to use the Valsalva manoeuver to stop paroxysms of orthodromic atrioventricular tachycardia (POAVRT) in the first trimester of pregnancy. If the manoeuver is ineffective, it is advisable to use Propanorm or combination of Propanorm with Valsalva manoeuver

Toward an indexing approach to evaluate fly ashes for geopolymer manufacture

Variations between fly ashes can lead to significant differences in the geopolymers derived from them, in both microstructural and mechanical properties. This study assesses the effect of physical, crystallographic and chemical characteristics of fly ash on geopolymerisation performance and the strength of the resulting binders. Physical and glass chemistry factors are combined to develop a comprehensive index to evaluate the suitability of fly ashes for the production of high-strength geopolymers. An equation for this index is proposed, developed using five typical low-calcium fly ashes and then validated against a further eight literature datasets, showing a good relationship between the ranking order of the calculated index and the compressive strengths of geopolymer pastes produced with comparable activator and paste workability. This index can be used to screen the source materials, which is of significant value in moving alkali activated cements towards acceptance in practice