A substitute or substitute good in economics and consumer theory is a product or service that a consumer sees as the same or similar to another product.
Postural orthostatic tachycardia syndrome (POTS) is one of a group of disorders that have orthostatic intolerance (OI) as their primary symptom.OI describes a condition in which an excessively reduced volume of blood returns to the heart after an individual stands up from a lying down position.n POTS, the lightheadedness or fainting is also accompanied by a rapid increase in heartbeat of more than 30 beats per minute, or a heart rate that exceeds 120 beats per minute, within 10 minutes of rising. The faintness or lightheadedness of POTS are relieved by lying down again.
Unfortunately and frustratingly there is no one clear cause of POTS Syndrome. In the following section we will discuss causes of POTS. Older people with POTS will have it due to another disorder such as diabetes or other condition. It is known as secondary POTS in that case, because it is secondary to something else.hlers-Danlos syndrome is more common amongst POTS patients than the general population (Wallman et al). It has been suggested that this is due to weakness in the blood vessels leading to pooling of blood in the lower extremities, a mechanism that has been well associated with the POTS syndrome (Rowe et al).