Considering the above information, it can be seen that in an average individual, nearly the entire volume of blood passes through the heart every minute! It is important to note that the cardiac output of the left heart must equal that of the right heart. This is important in order to prevent blood accumulation in one or the other circulation. Under pathological conditions in which the left ventricle is damaged (e.g., after myocardial infarction), the left heart is unable to keep pace with the right heart. This results in fluid backing up in the pulmonary circulation, which ultimately leads to fluid effusion into the pulmonary gas exchange sacs (alveoli). The accumulation of fluid in the alveoli hinders normal gas exchange in the lungs (O₂ gain and CO₂ elimination). This condition is referred to as pulmonary edema and, depending on its severity, it may be fatal.

The human heart is an amazing machine. As mentioned above, on average, the heart contracts 70 times per minute. Thus, the heart beats 4,200 times in one hour, 100,800 times in one day, 36,792,000 times in one year, and over a lifetime of 75 years, it beats 2,759,400,000 (2.7 billion times)! The heart’s volume output (i.e., cardiac output) is also phenomenal. As noted above, on average, each ventricle pumps 4.9 liters of blood every minute. Thus, each ventricle pumps 294 liters of blood per hour, 7,056 liters per day, 2,575,440 liters per year, and over lifetime of 75 years, 193,158,000 liters of blood (51,026,945 gallons)! As there are two ventricles, and the output of the left and right ventricles must be equal under healthy conditions, the total volume output of the heart is twice the numbers given.