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| Aortic stenosis |
AORTIC STENOSIS
-The site of obstruction may be at the level of valve, above the level (supravalvar) or below valve (subvulvar)
1 ) At the level of valve the stenosis either results frm an unicuspid or bicuspid aortic valve.
2) Supravulvar due to stenosis in root of arota above the aortic valve .
3) Subvalvar :- may be
i) discrete membranous valvar stenosis
ii) fibromuscular subvalvar aortic stenosis
iii) idiopathic hypertrophic subaortic sten..
HEMODYNAMICS :-
1) Obstruction at aortic level causes increase in systolic pressure of left ventricle,which results in concentric hypertrophy of the left ventricle.
2) This causes prolonged emptying of ventricle, hence causes delayed closure of aortic valve , thus there is delay io A2.
3) This delay causes Aortic Ejection Murmur. It is typicaly of DIAMOND SHAPED. starting from 1st sound and ending before Aortic component component of 2nd sound with Mid-Diastolic peak.
4) The systolic murmur is always palpable as thrill at 2nd rt interspace, suprasternal notch and thd carotid vessels.
5) The prolonged ejection results in the characteristic pulse which can be best described as slowly rising to peak which is sustained and then has a slowly rising to peak which is sustained and then has a slow down-slope.The peak is low so that pluse is low in amplitude and prolonged duration.
6) lt. Ventricular hypertrophy results in increased diastolic pressure causing lt. atrial hypertrophy which is felt as an palpable as well as audible 4th sound during lt.atrial contraction.
7) when lt.ventricle starts failing in aortic stenosis it starts to dialate along with hypertrophy resulting in audible 3rd sound
8) in vulvar aortic stenosis there is post-stenotic dilation of aorta which is absent in supravalvar and subvalvar type.9) there is associated ejection click which follows 1st sound. It is well heard at apex and along lt sternal border.
CLINICAL FEATURES :-
1) with mild to moderat AS symptoms are less or pt. is asymptomatic.
2) with sever form pt has Dyspnea on exertion., pt also has History of angina on effort and Syncope . Presence of any 1 of these suggest sever aortic stenosis.
3) more the severity of aortic stenosis narrower the pulse pressure. This gives pulse the charactestic low amplitude prolonged duration.
4) In sever cases apical impulse is forcible and 4th sound is palpable
5) 1st sound is normal follwed by ejection click. 2nd sound is (A2) delayed but not diminished in intensity. 2nd sound is closely split , single or paradoxicaly split
6) ejection systolic murmur starts after ejection click reach peak in mid-systol.
With increasing severity the peak is audible to end rather than at mid systol.
7)absence of click and post aortic dilation differntiate subvalvar frm valvar.
8) aortic regurgitation murmur may be present or absent.
9) in supravalvar (william's syndrom) since the obstruction is above the level of valve loud A2 is heard.
TREATMENT :-
1) Balloon aortic valvuplasty :-
- It is a non surgical procedure in which a balloon is introduced in femoral artery , placed at aortic level and inflated. It is indicated when gradient is above 75mm.
- At present it is treatment of choice in valvar and discrete subvalvar aortic stenosis.
- Sever associated aortic regurgitation is only contraindication .
2) Surgical treatment :-
- Indicated when significant aortic regurgitation is associated.
- two surgical procedures
i) Aortic valvotonmy
ii) Aortic valve replacement
are in use.
- those who undergone valvotmy may develop aortic regurgitation later. And those on prosthetic replacement should be kept on anticoagulants.
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