The cardiovascular system refers to the pumps, tubes and rhythm control systems that “drive” and “deliver” blood throughout the body. It can be roughly divided into these parts: heart, valves, coronary arteries, great vessels, and cardiac conduction system. The first small article describes the heart and heart valves. The heart consists of two ventricles, the left and the right, and two atria, the left atrium is connected to the left ventricle and the right atrium is connected to the right ventricle, which are equivalent to the two-cylinder engine of the human body. The left atrium is responsible for collecting the arterial blood after oxygenation of both lungs, and then feeding the oxygen-rich arterial blood to the whole body via the left ventricle. The right atrium is responsible for receiving venous blood from the systemic circulation and then pumping the oxygen-deficient venous blood into the lungs via the right ventricle for re-oxygenation. When lesions occur in the “heart muscle,” which makes up the bulk of the heart, such as various types of cardiomyopathy, the systolic and diastolic functions of the heart are affected, resulting in cardiac insufficiency. Heart valves are located at the inlet and outlet of the left and right ventricles, which are equivalent to the inlet and outlet valves of an engine cylinder, and they act as one-way valves to ensure that blood flows in a fixed direction in the heart. The inlet valve of the left ventricle is called the mitral valve and the outlet valve is called the aortic valve; the inlet valve of the right ventricle is called the tricuspid valve and the outlet valve is called the pulmonary valve. When a valve becomes diseased, it affects the function of the valve. The lesion can manifest as valve stenosis (the valve does not open completely), valve insufficiency (the valve does not close completely), or both stenosis and insufficiency. Generally speaking, cardiovascular structural abnormalities at birth are called “congenital heart disease”, while heart diseases that develop gradually after growing up are called “acquired heart disease”, such as coronary heart disease, valve disease, heart tumors, large vessel disease and arrhythmia.