The simplest, most accessible method to notice the movement of blood through the heart is using your ears. Physicians use a stethoscope to amplify the "lub-dub" sounds of heart valves, which open and close to facilitate blood flow in the correct direction through the circulation. Your heart is constantly responding to anatomic exercises by adjusting the movement of blood throughout the body; various physical maneuvers can alter how blood moves through your heart.
Heart Anatomy
The heart is composed of four chambers: the right and left atria and the right and left ventricles. The atria are responsible for collecting the blood returning to the heart through veins and channeling it into the ventricles, which are larger, more muscular, and located beneath the atria. Once the ventricles have filled with blood, a wave of contraction swells over them, causing rapid contraction and ejection of blood out of the heart. The right side of the heart is responsible for collecting blood from the peripheral circulation, directing it into the right ventricle, and finally pumping it into the lungs for oxygen absorption. The left side of the heart pools the blood returning from the lungs and funnels it down into the left ventricle, where it can be pumped out to all organs of the body.
Heart Valves
In order for blood to flow in one direction, the heart is equipped with a system of valves. For example, when the atria contract, blood is directed through a pair of valves into the ventricles. Similarly, when the ventricles contract, the increased pressure forces a pair of exiting valves to open and allow the smooth ejection of blood out of the heart. These valves make it possible for the heart to circulate blood by simply squeezing the walls of its chambers together, which increases the fluid pressure and forces blood through the valves.
Murmurs due to Mitral Regurgitation
One key finding in a heart exam is anything related to a defective valve. In the case of mitral regurgitation, the valve separating the left atria from the left ventricle does not properly close. Consequently, small amounts of blood leak backwards, hence the name "regurgitation". There are several anatomical exercises you can perform to alter the flow of blood through the mitral valve, thus changing the volume of the murmur. The act of squatting increases the rate of venous return to the heart -- you are literally squeezing the blood out of your legs. As you increase the volume of blood circulating through your heart for that instant, the amount of blood leaking through the mitral valve will increase as well. This change is observed with increases in murmur volume. When you stand up, however, the return of venous blood falls to normal levels, thus decreasing the rate of blood flowing through the mitral valve as well as the intensity of the regurgitating murmur.
Applications
Physicians can make diagnoses on the anatomy and functionality of your heart based on observations during the heart exam. These various maneuvers and exam techniques may be used to emphasize and examine the defect by adjusting the movement of blood through the heart.
References
- "Pathophysiology of Heart Disease"; Leonard Lilly; Fourth Edition
- A Practical Guide to Clinical Medicine: Exam of the Heart; Charlie Goldberg; 2011
