Acyanotic Heart Disease - Symptoms, Risk factors and Treatment

Acyanotic heart disease is a type of congenital heart disease in which there is no interference with the oxygen levels in the blood.

Congenital heart diseases are of two types- cyanotic and acyanotic. In Cyanotic heart diseases, there are low levels of oxygen in the circulation due to defects in the heart. On the other hand, acyanotic diseases most often do not have low levels of oxygen in the circulation.

Cyanosis is a bluish discoloration of the skin due to low levels of oxygen in the blood. As mentioned earlier, in acyanotic heart diseases, the oxygen levels are often not compromised. Therefore, cyanosis does not develop, hence the name "acyanotic"-meaning without cyanosis. 

In some acyanotic heart diseases, blood flows from the left side of the heart to the right side- a condition known as left-to-right shunt. 

Understanding The Normal Functioning of The Heart

Your heart has four chambers, the upper two atria. And the lower two ventricles, and two sides- the left side and the right side. The right side of the heart pumps blood to your lungs to receive oxygen, while the left side of your heart receives that blood from the lungs and pumps it to the whole body. The left side of the heart has oxygenated blood and the right side of the heart has deoxygenated blood.

Since there is a left-to-right shunt in acyanotic heart disease-means the oxygenated blood mixes with deoxygenated and not vice-versa. Due to this, oxygen levels are not lowered in the circulation mostly.

Signs and Symptoms of Acyanotic Heart Disease:

• Cough
• Breathlessness
• Weakness and fatigue
• Increased sweating
• High heart rate (Tachycardia)
• Deep breathing
• Faster breathing (Tachypnea)
• Mild cyanosis due to heart failure

Six different diseases come under the umbrella of Acyanotic heart disease:

1. Ventricular Septal defect (VSD)

2. Patent Ductus Arteriosus (PDA)

3.Atrial septal defect (ASD)

4. Pulmonary Stenosis

5. Aortic Stenosis

6. Coarctation of the aorta

In the above-mentioned diseases, ventricular septal defect, patent ductus arteriosus, atrial septal defect are due to left-to-right shunt. Whereas pulmonary stenosis, aortic stenosis, and coarctation of the aorta are due to outflow obstruction.

Ventricular Septal Defect:

It is a defect in the wall that separates the lower chambers (ventricles) of the heart. This wall is known as the ventricular septum, and since in this condition, it is not formed properly, hence the name is ventricular septal defect. 

In this condition, there is a hole in the ventricular septum, that may range in size, resulting in blood mixing between the two chambers. 

Patent Ductus Arteriosus (PDA):

It is a condition in which the ductus arteriosus fails to close after birth. Patent means opened. Hence the name patent ductus arteriosus.

Ductus arteriosus is a blood vessel that is present in fetal life and closes after birth. It connects the pulmonary artery with the descending aorta to bypass the nonfunctional fetal lungs.

PDA causes the blood from the aorta to mix with the pulmonary artery, hence sending oxygenated blood again for oxygenation in the lungs.

Atrial Septal Defect:

It is a defect in the wall separating the two upper chambers of the heart, the atria. This wall is called the atrial septum. In this condition, there is an opening present, that ranges in size, in the atrial septum. Since the atrial septum is defective, hence the name, atrial septal defect. In this condition, the blood between the two atria mixes. 

Pulmonary Stenosis:

It is a condition in which the pulmonary valve is narrowed, making blood flow harder. The pulmonary valve is present between the pulmonary artery and the right ventricle, ensuring a uni-directional flow of the blood. In pulmonary stenosis, since the valve is narrowed and it is harder to pump blood, the right ventricle increases in size (Ventricular hypertrophy).

Aortic Stenosis:

It is a condition in which the aortic valve of the heart is narrowed. The aortic valve is present between the left ventricle and the aorta. It ensures a unidirectional flow of the blood. Narrowing of the aortic valve makes it harder for the left ventricle to pump blood and may result in its enlargement, medically known as left ventricular hypertrophy.

Coarctation of Aorta:

It is a condition in which the aorta is narrowed at the time of birth. Like aortic stenosis, it makes it harder for the left ventricle to pump blood and may result in its enlargement.

Risk Factors:

Since these diseases are congenital, many factors during pregnancy can affect the normal development of the baby's heart;

Infections:

Rubella infection during the first trimester of pregnancy can affect the normal development of the baby's heart.

Alcohol intake:

Mothers consuming alcohol during pregnancy can affect the baby's heart that may cause fetal alcohol syndrome (FAS).

Medications: 

Medications like thalidomide, ACE inhibitors, acne medications, lithium, or some anti-seizure medications can result in fetal heart deformities.

Smoking:

Smoking cigarettes during pregnancy can result in the baby having congenital heart defects.

Maternal Illnesses:

Maternal illnesses like phenylketonuria (PKU), diabetes, SLE, vitamin B deficiency, or folic acid deficiency can result in fetal heart malformations.

Conclusion 

Acyanotic heart disease is a type of congenital heart disease in which the oxygen levels are near normal in the blood, and there is no cyanosis. But sometimes, cyanosis may be present due to heart failure.

Acyanotic heart disease can be treated by surgery and repairing the underlying defect that results in symptoms. Avoiding risk factors during pregnancy can prevent fetal heart defects.