The function of the Cardiovascular System is to circulate blood. When the circulation of blood is not enough to meet demand the term Cardiovascular Insufficiency is appropriate. This is not the same as Heart Failure, which is a diagnosis representing a disease state. The term Cardiovascular Insufficiency is a statement of function, the situation that the supply of blood does not meet demand. This is most often a natural process that supplements energy for times of increased need. It is not life threatening most of the time as it is easily limited simply by rest as in a middle distance runner crossing the finish line or otherwise limiting the intensity of activity. To indicate the need for a particular treatment or to bill an insurance company a diagnosis is necessary. The tern Cardiovascular Insufficiency is not appropriate as a diagnosis. It is helpful to have a term that avoids this implication that is necessarily pathological or represents a disease.
It is important that Cardiovascular Insufficiency is a process in healthy people as well as in those that have disease. The demand for blood can easily overwhelm the supply with exertion in healthy persons as the demands of the cardiovascular system vary greatly with activity. Running, swimming, wrestling etc increase the demand much above baseline. When this happens a part of the energy expenditure will come from anaerobic metabolism This mechanism for supplementing energy needs has evolved over millions of years and is safe so long as resting is possible. If illness is causing the increased demand and not exertion, the situation is serious if not grave.
When the demand exceeds the supply of blood the effects are regional. The muscle tissues are the most affected by high demand. These suffer a relative lack of oxygen and carry out the production of energy with oxygen requiring metabolism but also with anaerobic metabolism. The increased demand for oxygen can be dramatic, notably in athletes engaged in high intensity sports like sprinting.
Other tissues have lower metabolic requirements at baseline and are not significantly affected by exertion. Bone, neural tissue, etc. will not suffer from this metabolic imbalance. Importantly the skin is not a highly metabolic tissue and will not suffer the relative lack of oxygen from the imbalance of supply and demand. For this reason cardiovascular insufficiency does not lead to cyanosis even as an oxygen debt is accumulating. Runners develop an oxygen debt very rapidly but do not develop significantly lowered oxygen levels in the blood and do not appear cyanotic.
Cardiovascular Insufficiency becomes pathological when it can’t be stopped. Anaerobic metabolism produces energy without using oxygen but the process is temporary. It produces lactic acid which accumulates with high levels of activity. Bicarbonate buffer in the blood and increasing tendency toward acidemia. The athlete cane easily reduce or resolve this issue it anytime by resting.
The supply of blood and therefor oxygen.
Often there is a mix of both limited supply and some measure of excessive demand. When demand exceeds supply for whatever reason, anaerobic metabolism will develop.
When Cardiovascular Insufficiency develops lactic acid is produced and begins to accumulate. This partially deficiency in the production of energy.This happens in health and disease. The total amount of lactic acid begins to rise and an acidemia develops. The process of metabolic acidosis from this anaerobic metabolism leads to falling bicarbonate levels. T A sensation of shortness of breath develops as a result of this cardiovascular insufficiency. This is notably seen in runners after a race particularly the “middle distance” races like 800 meters or 1600 meters.
Anaerobic metabolism, energy production without oxygen, in humans and indeed in all mammals produces lactic acid. There are other types of anaerobic metabolism most notably fermentation which occurs in yeast and other microorganisms which produces ethanol,but in humans anaerobic metabolism produces lactic acid. Some authors refer to anaerobic metabolism as anaerobic respiration. This is an unfortunate term as respiration refers to breathing, the function of which is to oxygenate the blood. There is nothing about anaerobic, meaning without oxygen that breathing would support. Breathing, that is respiration does not support anaerobic metabolism in any way. Anaerobic respiration is an oxymoronic, ridiculous term preferred by authors with a conflict of interest and prefer that exercise does not produce anything toxic like lactic acid. The fact that strenuous exercise does naturally produce a substance that in high enough concentrations would be fatal is not consistent with the marketing campaigns of gyms, personal trainers and similar businesses. In an insidious and roundabout way this influences publications to misinform the public. Understanding this conflict of interest would help the public to understand what is meant by the terms anaerobic and aerobic. To put is simply, anaerobic refers to the absence of oxygen. Respiration or respiratory refers to breathing, oxygen.