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| * To nilkanth,effects of manuvers on systolic murmur |
| | #305884 |
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Lets first take AS:
*Valsalva: this manuver actually has four phases,but the effects of murmurs are mostly described during phase 2.(I can also post the four phases later,so that u shouldnt get confused rt now)
Reduced filling and preload leads to a fall in cardiac output by the Frank Starling mechanism.
So murmur will decrease as thier is less blood available to eject during systole(decrease in CO)
*Phenylephrine and hand grip: causes an increase in systemic vascular resistance and arterial pressure ,causing a lower cardiac output.
So again murmur will decrease.(increase TPR can actually accentuate the murmur but resultant decrease in CO is more pronounced).
*Squatting:Squatting from a standing position is associated with an increase in venous return and systemic vascular resistance and a rise in arterial pressure.
So intensity of the murmur of aortic stenosis shows variable changes, depending upon the type of hemodynamic response,if increase in systemic vascular resistance is more then murmur will decrease (again due to dec CO),
but if left ventricular volume increases more then murmur will increase.
*Amylnitrate: initially produces marked vasodilation and reduction in arterial pressure. This is followed by a reflex increase in heart rate and then by increased venous return, stroke volume, and cardiac output.
So murmur will increase due to increase CO.
*Leg raising:increases venous return,inc CO and So increase in murmur.
So AS murmur increases with manuvers increasing CO and decreases with manuvers decreasing CO.
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| * Re:To nilkanth,effects of manuvers on systolic mur |
| #1328514 |
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HOCM:For this imp to know the pathophysio that there is asymetric septal hypertrophy of interventricular septum.And ventricular flow is narrowed during systole b/w buldging septum and an anteriorly displaced mitral valve.
Anything that will worsen the obstruction will increase murmur.Now obstruction can be worsened by:
1.factors that increase myocardial contractility,
*sympathetic stimulation and digoxin
2.factors that decrease LV filling
*valsalva manuver
*peripheral vasodilators(amyl nitrate)
Anything which increases LV filling wil decrease the murmur:
*Squatting
*Leg raising
*Phenylephrine and hand grip(peripheral vasoconstriction though decreases the CO,and led to decrease of AS murmur but venous return is still increase due to more blood pushed to venous system as compared to arterial,so leading to same effect in HOCM,but by a dift mechanism) |
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| * Re:To nilkanth,effects of manuvers on systolic mur |
| #1328625 |
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VSD:
This holosystolic murmur deosnt depend on CO(as nothing wrong with outflow) ,rather increase VR is more imp.
So anything causing increase VR will increase the murmur as more blood available to flow through the shunt.
*Phenylephrine (more VR,but less CO due to in TPR)
*Leg raising
Anything decreasing VR will dec the intensity:(or dec Vent filling)
*Valsalva
*Amyl nitrate
Now what happened in squatting:
inc VR to the rt side of heart will balance the inc preload to lt heart and so "no change" in intensity.
Hi mobi,urw,actually by knowing mechanism u can skip the memorization :):) |
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| * Re:To nilkanth,effects of manuvers on systolic mur |
| #1328650 |
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Mitral Regurg:same mechanisms and same change in intensity as in VSD.
Now why kaplan says "slight dec" with valsalva.coz always remember valsalve manuver leads to more effects on the rt side of the heart,so left side is less effected and change in murmur intensity of mit regurg is slight.
Hope that helps u nilkanth. |
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