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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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