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The amazing structure of AVSD: Why does this heart defect leave babies with breathing difficulties?
Atrioventricular Septal Defect (AVSD) is a congenital heart defect in which the atrioventricular septum of the heart is insufficient, resulting in a connection between the four heart chambers. This defect often has serious consequences for the baby's physiological functions, especially in the respiratory and circulatory systems.
AVSD is a special combination of three defects: atrial septal defect (ASD), ventricular septal defect (VSD), and abnormalities of the mitral and/or tricuspid valves.
The causes of AVSD usually involve poor development or incomplete fusion of the upper and lower endothelial pads with the middle part of the atrial septum and the muscular portion of the ventricular septum during heart development. Unlike some other heart defects, AVSD does not repair itself over time, and most babies require open-heart surgery to treat it. The success rate of this procedure is usually high, and most babies recover well after the procedure.
Symptoms and symptoms
Symptoms of AVSD may include difficulty breathing and bruising (cyanosis) of the skin, nails, and lips. Babies will begin to show signs of congestive heart failure, which may include rapid breathing, difficulty feeding, slow weight gain, low energy, and cold sweats. These symptoms usually appear within 1 to 2 months after birth, but in some newborns they may appear earlier.
Complications
Normally, the heart's four chambers separate oxygenated and deoxygenated blood. However, when gaps occur (as in the case of AVSD), blood between these chambers can mix. This results in less than normal arterial blood oxygenation and triggers hypoxia and cyanosis. In this condition, the heart must work harder to pump blood to provide enough oxygen, which can lead to heart enlargement and hypertrophy. Developing pulmonary hypertension is a very serious problem because the left ventricle weakens from overuse. When this happens, pressure can flow back into the pulmonary veins and lungs, causing irreversible damage, so it's important to treat it immediately after diagnosis.
Related diseases
AVCD is often associated with Down syndrome. Other risk factors include having a parent with a congenital heart defect, alcohol use during pregnancy, uncontrolled diabetes during pregnancy, and certain pregnancy medications. About 45% of patients with Down syndrome have congenital heart disease, of which 35-40% have AV defects. According to statistics, about 40-50% of fetuses are diagnosed with AVCD during examination, while another 15-20% are associated with other chromosomal abnormalities and syndromes (such as DiGeorge syndrome), and the remaining 30-40% are not shown associated with any syndrome. AVCD is also associated with Noonan syndrome, and those with the condition have different symptoms than those with Down syndrome.
Pathophysiology
Bad embryonic heart formation results in multiple gaps between the ventricles. In the case of AVSD, the four heart chambers are interconnected, but the specific characteristics of the gap and deformity vary from patient to patient. Even between "complete" and "partial" AVSD, there are many different conditions with different clinical consequences. The clinical and physiological manifestations of the condition may change over time and be affected by ongoing stress.
Diagnosis
AVSD is usually detected by cardiac auscultation and produces unusual murmurs and increased heart sounds. Cardiac ultrasound (cardiac ultrasound) can be used to confirm the results of heart auscultation, which is a more non-invasive test, while cardiac catheterization is a more invasive option. Prenatal diagnosis can also be done with a routine fetal ultrasound or a more specific fetal heart ultrasound.
Treatment
Treatment is usually surgical and involves closing the atrial and ventricular septal defects and restoring function of the left atrioventricular valve. These open surgeries require the use of a cardiopulmonary bypass machine and are completed through a median sternotomy. For uncomplicated upper atrial septal defects, the mortality rate of surgery is 2% in experienced centers and less than 4% for complete AVCD cases. If the surgery is not performed immediately after birth, the newborn will be monitored closely for several months until the first signs of lung or heart failure appear. This gives the baby some time to grow and facilitates surgical procedures.
Conclusion
AVSD is a complex and far-reaching heart defect that, through early diagnosis and appropriate treatment, can significantly improve an infant's quality of life and chances of survival. However, with the development of medical technology, will there be better treatments in the future to further protect these fragile lives?
