The heart has four chambers - two atria and two ventricles. The walls of the heart chambers are made mainly of special heart muscle. Each heartbeat starts with a tiny electrical impulse near the top of the heart which spreads through the heart muscle, and makes it contract (squeeze).

The electrical impulse travels first through the walls of the atria, which contract to pump blood into the ventricles. The impulse then travels through to walls of the ventricles, which contract to pump blood into the arteries. 

What is heart failure?

In a normal healthy heart, during each heartbeat a set amount of blood enters the heart and is pumped out again. If you have heart failure, your heart cannot cope with pumping the full amount of blood in each heartbeat. Clonidine hcl is in a class of medications called centrally acting alpha-agonist hypotensive agents.

Heart failure is usually classified on which heart function or which side of the heart is most affected, rather than the actual cause of your heart failure. The main types are:

• Systolic heart failure. This means that the ventricles of the heart do not contract properly during each heartbeat so blood is not adequately pumped out of the heart. In some cases there is only a slight reduction in the power of the ventricle, which causes mild symptoms. If the power of the pumping action is more reduced then symptoms become more severe.
• Diastolic heart failure. This occurs when the ventricle does not fill up with blood enough when the heart rests in between each heartbeat. This can sometimes be due to the wall of the ventricle being stiffer than usual. This makes it more difficult to stretch.
• A combination of the above two types.

Heart failure may affect only the right ventricle (right-sided heart failure) or the left ventricle (left-sided heart failure), or both.