Defects Of The Human Heart

1574 WordsJul 29, 20157 Pages
In order to understand defects of the human heart, it is important to first understand its development. Initially, the fetal heart is a simple tube, consisting of just three layers and three specific areas. These primitive layers later develop into the myocardium and epicardium of the heart. The areas – cranial (head) end, caudal (tail) end, and bulbus cordis – eventually form the aorta and ventricles. Around the third week of pregnancy, the fetal heartbeat can be seen as a flicker on the ultrasound monitor. At this stage, the heart organizes into two chambers – one atrium on the left and one on the right. Structural defects are most likely to occur during this time of development. Eight weeks after conception, the fetal heart consists of…show more content…
In a healthy heart, the aorta is attached to the left ventricle for transportation of oxygen-rich blood to the body. An overriding aorta, another defect of tetralogy of Fallot, is one in which oxygen-poor blood flows directly into the aorta instead of into the pulmonary artery due to the aorta’s position between the left and right ventricles. Narrowing of the pulmonary valve and the main pulmonary artery – called pulmonary stenosis – is the third defect of tetralogy of Fallot. This obstruction forces the heart to work harder and deprives the lungs of adequate amounts of oxygen-rich blood. Because the heart is pumping at high pressure to move blood through the narrowed pulmonary valve, the muscle of the right ventricle becomes thicker than usual. This defect is known as right ventricular hypertrophy. A small percentage of children with tetralogy of Fallot may also suffer from an atrial septal defect (ASD). This is a hole in the septum that separates the atria of the heart. This defect causes blood to flow directly from the left atrium to the right atrium, increasing the blood pressure in the lungs to dangerous levels. Heart conditions among newborns are relatively common, affecting almost 1 in 100 American babies. Of these, tetralogy of Fallot accounts for 8-10% of all congenital heart diseases among newborns. Although tetralogy of Fallot affects males and females equally, it is seen more commonly in children with Down
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