| Cyanotic defects are those in which | | | | Fallot. During infancy, the most characteristic |
| un-oxygenated blood is mixed with oxygenated | | | | positions are either flaccid with the extremities |
| blood in the systemic circulation. Improvements in | | | | extended or side lying with the knees bent |
| surgical techniques have significantly increased the | | | | towards the chest (knee-chest position). Continual |
| outlook for children with these defects. | | | | muscle contraction demands additional oxygen. |
| Compensatory mechanisms | | | | Flaccidity is usually a sign of severe cardiovascular |
| A number of compensatory mechanisms occur in | | | | compromise. |
| cyanotic defects in response to decreased arterial | | | | The knee-chest position and, later in childhood, the |
| oxygen saturation. These include polycythemia | | | | squatting position serve two purposes. First, |
| and the characteristic squatting posture seen with | | | | flexing the legs decreases venous return from |
| teratology of fallout. | | | | the lower extremities, which have very low |
| Chronic arterial oxygen saturation in cyanotic | | | | oxygen content, especially after exercise. |
| heart disease causes decreased tissue, | | | | Consequently a smaller volume of this blood |
| oxygenation, which stimulates erythropoiesis, This | | | | enters the right ventricle so that the blood |
| results in the production of large numbers of red | | | | shunted into the aorta has a higher oxygen |
| blood cells, a condition known as polycythemia. | | | | content. Second, squatting increases systemic |
| This compensatory response is to carry | | | | vascular resistance, which diverts right ventricular |
| supplemental oxygen by means of: | | | | blood from the aorta into the pulmonary artery, |
| increased quantity erythrocytes. | | | | increasing pulmonary blood flow. This increases |
| Increase volume of blood | | | | the amount of oxygenated blood in the left side |
| Forcing the heart to work even harder | | | | of the heart and eventually into the systemic |
| Circulation is impeded, especially in the | | | | circulation. |
| capillaries, the blood that is able to carry additional | | | | Though with the advancement of medical science |
| oxygen is not able to reach the peripheral | | | | and clinical diagnostic and treatment methods, the |
| circulation | | | | infant mortality rate as a result of congenital |
| Dehydration presents further hazards t the | | | | heart disease of the cyanotic type has drastically |
| child because of the increased hemoconcentration | | | | reduced when compared to the time of the 70s |
| Polycythemia is evident in hematologic test | | | | and the 80s. Hence handling and controlling of such |
| Increased ratio of red cells to plasma | | | | ailments have proven to be highly successful in |
| Hemoglobin levels are usually elevated | | | | our modern era, especially my surgical method. |
| Posturing | | | | Yet, they still poise a threat to infant mortality |
| Posturing is a compensatory mechanism | | | | and should be taken very seriously. |
| automatically learned by the child with teratogy of | | | | |