A stiff heart, also called diastolic dysfunction or cardiac amyloidosis, is a condition in which the muscle tissue of the heart becomes stiff, as its name suggests. It is most frequently caused by high blood pressure and impairs the heart's ability to fill completely with blood and consequently, its ability to supply the rest of the body with blood. It can result in fluid buildup in the lungs and cause the heart to overwork. If left untreated with medications, it can result in heart failure and death.
The stiffness of the heart impairs its ability to beat properly. When a stiff heart beats, it cannot fill itself completely with blood. The amount of blood that the heart pumps into the rest of the body is reduced if it doesn't fill completely. The amount of the reduction of blood to the rest of the body is directly related to the amount of blood missing in the heart.
The stiff heart will try to make up for the decreased blood flow by working harder. This will usually do a lot more harm than good. The heart is already not functioning properly and the increased heartbeats will supply only a marginally larger amount of blood. Unfortunately, it will also overwork the heart, which will exacerbate the dysfunction.
A stiff heart can sometimes cause blood to become backed up in the lungs. Normal function of the heart involves old, deoxygenated blood to pump into the pulmonary artery, which carries it to the lungs for oxygenation and filtering. The blood is then supplied back to the left atrium and ventricle, then out through the aorta to the rest of the body. When the heart isn't pumping properly, there may not be enough pressure to move the blood out of the lungs and back into the heart.
The blood normally remains within blood vessels, but the reduced force of the pumping heart can cause the blood to leak into the lung air sacs. This condition is called pulmonary edema and is more commonly known as fluid in the lungs. This same leaking can occur in the legs, ankles, or feet, as this region of the body requires the most force to continue proper blood flow.
A stiff heart can usually be treated with prescription medication. Beta blockers may be prescribed and have been known to actually decrease the stiffness in the muscle tissue in the heart. Other medications may be used to relax the heart in order to decrease the amount of work it has to do. Diuretics can be used to drain the body of excess fluids building up in the legs or lungs. If the stiffness was caused by high blood pressure, a treatment program will be developed separately for that.