Blood flow is often simplified by Ohm's law of hydrodynamics (flow = Δpressure/resistance), which applies to all vessels.



It has been demonstrated that there is also an increase in left ventricular cavity dimension, stroke volume, and arterial pressure and a decrease in heart rate and total peripheral resistance due to baroreceptor reflexes (Isometric exercise will result in minimal elevation of the heart rate with a significant increase of systolic and diastolic blood pressures leading to an increase in left ventricular afterload (We shall concentrate on the most common and clinically significant encountered murmurs in the adult patient. Journal of the American Academy of Physician Assistants, Vol. This high-velocity blood movement increases turbulence as well as a Venturi effect drawing the anterior mitral leaflet into approximation to the septum, causing a transient outflow obstruction.



Since flow in a vessel is most influenced by the radius of the vessel, one can assume that the decrease in coaptation of the mitral valve leaflets will lead to a greater radius of the incompetent area, facilitating regurgitation.

According to Bernoulli's principle, a decrease in flow will result in a reduced ejection velocity because the cross-sectional area of the aortic valve has not changed.
This abnormality is facilitated by the fact that some patients with HOCM have elongated mitral leaflets (Any maneuver that decreases left ventricular volume will exacerbate the anatomic aberrancy (by narrowing the outflow tract), increasing obstruction, the pressure gradient proximal and distal to the obstruction, and turbulence, thus increasing the intensity of the murmur.

The two most likely causes of an increased Reynold's number and therefore turbulent blood flow are increased velocity of blood flow and low viscosity (reduced hematocrit).

Downloaded 7,627 times This redundancy results in the prolapse of one or both of the leaflets of the mitral valve into the left atrium during systole. HOCM= Hypertrophic Obstructive Cardiomyopathy

Since increasing afterload will prevent blood from flowing in a normal forward path, it will increase any murmurs that are due to backwards flowing blood. The redundant tissue disrupts proper coaptation of the leaflets, facilitating valvular insufficiency, leading to a late mitral regurgitant murmur.

Understanding them requires a consideration of cardiovascular physiology. Interestingly, at high flow rates, flow rises to a lesser degree and is no longer proportional to driving pressure. approved final version of manuscript; J.L.B.
Increases in afterload will result in higher end-diastolic volumes and ultimately ventricular systolic pressure increasing the pressure gradient betwwen the left atrium and ventricle. As already explained in the previous maneuver, lesser blood inside left ventricle will increase the murmurs of HOCM and MVP due to the reasons already stated.





The murmur of hypertrophic cardiomyopathy (HOCM) is caused by turbulent flow in the left ventricular outflow tract (LVOT), which is the part of the heart just underneath the aortic valve. This is due to an increase in resistance, which is a consequence of turbulent or nonlaminar blood flow.

As described previously regarding Bernoulli's principle, the reduction in the cross-sectional area of the valve causes augmented jet velocity, increased Reynold's number, and a systolic ejection murmur (The effect of the Valsalva maneuver on the intensity of AS is shown in With squatting, due to the augmentation of venous return from the lower extremities, and the resultant bradycardia, there is an increase in stroke volume (During hand grip, as discussed above, there is an increase in left ventricular afterload, which causes an increase in the impedance to left ventricular emptying. In contrast to the Valsalva maneuver, which leads to a smaller preload, squatting increases end-diastolic volume due to increased venous return.

drafted manuscript; S.A.S., J.L.B., and D.M.H.





Since the venous circulation is a “low-pressure system,” the Valsalva maneuver interferes with venous return to the right side of the heart. Unfortunately, these findings can be present intermittently, making the clinical diagnosis at times difficult.

We will examine their effect on preload, afterload, chamber dimensions, and pressure gradients and correlate these findings to the anatomic induced aberrancy of flow responsible for the sound intensity and timing of murmurs.To better understand how these maneuvers can be used to characterize and decipher murmurs, it is necessary to review the basic principles underlying blood flow that contribute to these sounds. of Central Florida College of Medicine, 6850 Lake Nona Blvd., Orlando, FL 32827 (e-mail: University of Central Florida College of Medicine, Orlando, FloridaUniversity of Central Florida College of Medicine, Orlando, FloridaPhysiological principles that directly apply to physical diagnosis provide opportune occasions to bring basic science to the bedside.

MS= Mitral Stenosis


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