Purkinje fibers are not part of the cardiac conduction system. They are specialized muscle fibers that conduct electrical impulses from the bundle of His to the ventricular myocardium.

An action potential is a rapid change in the electrical potential across a cell membrane, causing the cell to depolarize and then repolarize.

Conductivity is not a mechanical property of the heart. It is an electrical property that refers to the ability of the heart to conduct electrical impulses.

Myocardial contractility is the force generated by the contraction of the heart muscle.

Lymphatic vessels are not blood vessels. They are part of the lymphatic system, which is a network of vessels that collects and returns fluid from tissues back to the bloodstream.

Blood pressure is the pressure exerted by blood on the walls of blood vessels.

Cancer is not a cardiovascular disease. It is a disease in which abnormal cells divide uncontrollably and can invade other tissues.

Coronary artery disease is the narrowing of the arteries that supply blood to the heart.

Regular exercise is not a risk factor for cardiovascular disease. It is a protective factor that can help to reduce the risk of cardiovascular disease.

Myocardial infarction is the death of heart muscle tissue due to a lack of blood flow.

Radiation therapy is not a treatment for cardiovascular disease. It is a treatment for cancer.

Stenting is the procedure in which a stent is placed in an artery to keep it open.

The pulmonary valve is not a heart valve. It is a valve in the pulmonary artery that prevents blood from flowing back into the right ventricle.

Valve regurgitation is the condition in which the heart valves do not close properly, allowing blood to leak back into the heart.

Down syndrome is not a type of congenital heart defect. It is a genetic disorder that can cause a variety of health problems, including heart defects.