The improper functioning of the heart may lead to certain disorders such as 

(i) Hypertension : A continuous or sustained rise in the arterial blood pressure is known as hypertension. The normal pressure in a healthy individual is 120/80 mm Hg. But increase in the blood pressure beyond 140/90 mm Hg is referred to as hypertension. High blood pressure can harm the vital organs. It compels the heart to work excessively, due to which congestive heart disease may set in. 

(ii) Coronary heart disease : (CAD) : It is also known as atherosclerosis. It affects the blood vessels that supply blood to the heart muscles. This is due to the deposition of fat, cholesterol and Ca⁺ and fibrous tissues on the walls of the arteries which results in the narrowing of the arterial lumen. 

(iii) Angina : It is also known as "angina pectoris" The symptom is acute chest pain. When adequate quantity of oxygen do not reach the heart muscles pain occurs. 

(iv) Heart failure : It is the state of heart which is not able to pump the blood effectively enough to meet the body needs. As congestion of the lungs is the main reason for this heart failure it is also known as congestive heart failure