Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Q. How to investigate aortic stenosis by Echo Cardiography?
2D Echo cardiogram shows the number of cusps. But presence of raphae and distorted anatomy due to calcification may make if difficult to assess. Localization of stenosis to sub-valvular or supra valvular or valvular location can easily be done. Ascending aorta may be disproportionately dilated in some patients with bicuspid aortic valve with a tendency for aortic dissection.
Hemodynamic severity of aortic stenosis can be measured by Doppler echocardiography. Peak and mean trans valvular aortic gradients, aortic valve area and ratio of LVOT and aortic valve time velocity integral (VTI) are important measurements. Meticulous search using all transducer positions should be made to obtain maximal aortic velocity. In patients with normal LV function and cardiac output, aortic stenosis is considered severe when peak aortic velocity is more than or equal to 4.5 m/sec; mean pressure gradient equal to or more than 50 mmHg, aortic valve area less than or equal to 0.75 cm2 or LVOT/Aortic valve VTI ratio less than or equal to 0.25. It should be noted that in-patients with left ventricular dysfunction and/or low cardiac output, transvalvular pressure gradients will be under estimated while in situations with increased flow across aortic valve like aortic regurgitation and/or anemia transvalvular gradient will be over estimated. Since in both these situation LVOT and Aortic valve VTI move in the same direction and value area as measured by continuity equation makes use of ratio of these two, valve area measurements tends to be more accurate. Also valve resistance which takes into account valve area and flow across the valve is a more reliable index. Further while following a patient serially with echocardiography combined use of transvalvular gradients, left ventricular function and valve area calculation are more useful. Otto and his colleagues have shown that in asymptomatic patients, peak aortic jet velocities increase by 0.32 ± 0.34 m/sec per year, mean gradient by 7± 7 mmHg and valve area decrease by 0.12 ± 0.19 cm per year. Beyond a peak velocity of 4.0 m/sec most of the patients become symptomatic within 2 years. Aortic valve area is d" 0.75 cm2 when peak aortic velocity is > 4.5 m/sec and mean gradient is e" 50 mm Hg. However, half of patients with aortic valve area d" 0.75 cm2 have lower peak velocities and mean gradients due to lower cardiac output.
Ratio of LVOT/Aortic valve VTI is another good index in measuring aortic valve area. A ratio of LVOT/AV VTI is < 0.25 correlates well with a aortic valve area of < 0.75 m2.
STRUCTUR E OF A MYOFIBRIL - The dark bands of the myofibril are termed the A-bands (Anisotropic bands). Each A-band has at its middle a light zone called H-zone (Henson'
Q. What is the production of the RNA called and what is the enzyme that catalyzes the procedure? The making of the RNA from information contained in the DNA is called transcrip
Plants are the source of a large variety of biochemicals which are metabolites of both primary and secondary metabolism. But secondary metabolites are of much greater interest s
What is peristomium. Describe? The segment behind the prostomium in annelids which contains the oral opening. This segment like the prostomium isn't a true segment and has no s
Determine about the Sense of Contrast It is the ability to perceive slight changes in luminance between regions which are not separated by definite borders. This is
Regulation of Glycolysis There are three markedly exergonic reactions in the glycolytic pathway, which are considered physiologically irreversible. These reactions are cataly
what is the relationship between an infection and spleen
Guards for Machines and Equipment Various machines and equipment used for manufacturing require guards for protecting the operator from any injury. These machines include: Wo
Q. In which meiotic division does the separation of identical chromatids take place? And After the end of this process what are the ploidies of the new cells? The separation of
Reviews - Assurance engagements The objective of financial statements of a review is to enable an auditor to state where, on the essential of procedures that do not give all t
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd