1. A Pump and Pipes--the Heart and Blood Vessels
In essence, the heart is simply a pump that forces fluid through a series of pipes. The pipes are the body's arteries and veins, and the fluid is blood. All systems of pumps and pipes must have valves to control the direction that fluid flows through the pipes. The heart and blood vessels are no different. Within the heart there are valves that direct the flow of blood. The term "valvular heart disease" refers to the circumstance where these valves allow blood to flow in the wrong direction or are narrowed.
2. How Does This Thing Work?
The heart has four chambers, two upper and two lower. The lower chambers are the pumps called ventricles. The upper chambers are the chambers that receive blood from the veins and then pass it on to the ventricles. The right side of the heart pumps blood to the lungs. The left side pumps it to the body. Each ventricle has a valve between its atrium and ventricle--the mitral valve between the left atrium and left ventricle, and the tricuspid valve between the right atrium and ventricle. The aortic valve controls flow out of the left ventricle. The pulmonic valve controls blood flow out of the right ventricle.
3. More Work for the Same Pump
If a valve becomes narrowed (stenosed), its pump has to work harder to push blood through the narrower opening. If a valve leaks, allowing backward flow, the pump also has to work harder because it becomes more inefficient. These are the basic problems in valvular heart disease. In aortic stenosis, the valve is narrow and the left ventricle develops problems because it has to work harder to get the necessary amount of blood through the narrow opening. In mitral valve insufficiency, some of the blood squirts back into the left atrium every time the ventricle beats. Here too, the ventricle has to work harder.
4. Murmurs
A murmur is simply the sound of turbulent blood flow. In a normal heart, there is very little turbulent flow. A narrow, roughened or leaky valve causes turbulent flow and produces a murmur. There are different murmurs corresponding to different problems. At one time, this was the primary way of initially figuring out what specific valvular problems existed. However, we now know that even the most skilled clinicians were often wrong about murmurs.
5. Understand Echocardiograms
The most common way to evaluate valvular heart disease is an echocardiogram. This test bounces sound waves off the heart and produces an image of not only what a valve looks like but how it functions. Modern echocardiograms are so accurate that they can estimate the amount of pressure left in the vascular system after the ventricles contract--the cause of so called valvular related diastolic hypertension.
