The tetralogy of Fallot is a mixture of 4 defects within the heart of a newborn:
- a ventricular septal defect;
- an overriding aorta;
- pulmonary stenosis (narrowing);
- right ventricular hypertrophy (enlargement).
Blood is prevented from flowing to the lungs by the pulmonary stenosis, which results in hypertrophy of the right ventricle. The ascending portion arises midway between the right and left ventricles rather than from the left ventricle only, in an overriding aorta. It is essential that open-heart surgery correct tetralogy of Fallot, and the overall mortality rate is nearly 5 percent.
When an inadequate supply of oxygen is received by a tissue receives for the reason of decreased blood flow, it is said to be ischemic. Atherosclerosis of the coronary arteries is the most usual cause of myocardial ischemia. The adequacy of blood flow is relative that it is according to the different metabolic needs of the tissue for oxygen, such as, perhaps permit sufficient blood flow at rest but probably form ischemia when the heart is stressed by exercise or emotional aspects. Coronary artery bypass surgery is perhaps performed in patients with this condition.
Myocardial ischemia is connected with increased concentrations of blood lactic acid, which is formed by anaerobic respiration of the ischemic tissue. Substernal pain, which is probably referred to the left shoulder and arm as well, and to other regions, is usually resulted from this condition.