Cardiovascular System and Heart Failure Module 1

Cardiovascular System

• Cardiovascular system, also known as circulatory system, consists of Heart, Blood vessels, and Blood.
• The heart's function is to pump blood throughout the body.
• The four chambers of the heart are:
  • Right atrium
  • Left atrium
  • Right ventricle
  • Left ventricle

Important Terms

• Systole: contraction of the heart, mainly the ventricles, during which blood is pumped to the arteries.
• Diastole: relaxation of the heart, mainly the ventricles, during which they are filled with blood.
• Heart rate (HR): the number of times the heart beats in a minute, normally around 72 beats per minute.
• Stroke Volume (SV): the amount of blood pumped by the ventricles in one beat, approximately 70 ml in a healthy individual.
• Cardiac output (CO): the amount of blood pumped by the heart in one minute, calculated by CO = Heart Rate x Stroke Volume.
• End Diastolic volume: the volume present in the ventricles at the end of diastole, approximately 110-120 ml.
• Ejection Fraction (EF): the fraction of the end diastolic volume ejected, calculated by EF = Stroke Volume / End Diastolic Volume, normally around 63%.

Heart Failure

• Heart failure (HF) is a chronic, progressive condition in which the heart muscle is unable to pump enough blood to meet the body's needs for blood and oxygen.
• Epidemiology:
  • HF leads to recurrent hospitalization in the elderly.
  • HF costs billions to healthcare and are increasing with ageing population and prevalence of major heart risk factors, lifestyle changes, and diabetes.
  • The first year after diagnosis, mortality risk is highest, at 40%.
  • The average life expectancy after diagnosis is 3 years.
• Diabetes is associated with a higher risk of HF:
  • Approximately 3 out of 10 people with type 2 diabetes (T2D) also have HF.
  • People with T2D are 2.5 times more likely to develop chronic HF than those without T2D.
• People with HF and T2D have reduced survival.