Introduction
The heart is a muscular organ in the middle of the chest, between the lungs, and slightly behind and left of the sternum (breastbone). It has four chambers: two at the top, the right and left atrium, and two at the bottom, the right and left ventricle. A wall of muscle known as the septum separates the right and left atria and the right and left ventricles. The atrioventricular or AV valves open between the atrium atria and ventricles. It includes the tricuspid valve (between the right atrium and right ventricle) and mitral valve (between the left and left ventricle). The semilunar valves open when the blood flows out of the ventricles. It includes the aortic valve, which opens when the blood flows from the left ventricle to the aorta (the largest artery in the body that carries oxygenated blood from the heart to other parts of the body), and the pulmonary valve, which opens when the blood flows from the right ventricle to the pulmonary arteries. The left ventricle is the heart's largest chamber, and the left ventricle walls are about half an inch thick, as blood needs to be forced into the aorta to be distributed to all the body parts.
What Is a Double Inlet Left Ventricle?
Double inlet left ventricle (DILV) is a congenital defect affecting the chambers and valves of the heart. It is one of the several defects in a condition known as single ventricle defects. In this condition, there is only one functioning ventricle, most commonly with the left ventricular structure. In most cases, it presents as a large left ventricle and a small right ventricle, which is not entirely developed and, hence, unable to pump blood to the lungs. In double inlet left ventricle condition, both the upper chambers of the heart are connected to the left ventricle, and hence the right and left atria empty blood into the left ventricle, which causes the mixing of the oxygen-rich blood with oxygen-poor blood, which is pumped to the lungs and other parts of the body.
What Are the Causes of the Double Inlet Left Ventricle?
Double inlet left ventricle is rare, and the exact cause is unknown. The problem mostly arises in early pregnancy when the heart develops. It accounts for less than two percent of all congenital heart defects (CHDs). Individuals with this defect may also be associated with other conditions such as pulmonary stenosis (narrowing of the pulmonary valve), pulmonary atresia (a defect in the opening of the pulmonary valve), coarctation of the aorta (narrowing of the aorta), etc. Double inlet left ventricle can also occur if the large blood vessels from the heart are located in abnormal positions, such as the aorta arises from the small right ventricle or due to a ventricular septal defect (the blood flows through a hole between the left and right ventricles).
What Are the Symptoms of Double Inlet Left Ventricle?
The signs and symptoms of double inlet left ventricle are mainly determined by the severity and the type of associated heart defects. Some of the symptoms include:
Bluish discoloration of the lips and skin due to less oxygen in the blood.
Abnormal heart rhythm.
Irregular or rapid heartbeat.
Accumulation of fluid around the lungs.
Heart murmurs.
Pale skin.
Excessive sweating.
Swelling in the abdomen and legs.
Poor feeding.
Difficulty breathing.
Poor weight gain and growth.
What Are the Complications of a Double Inlet Left Ventricle?
Some of the complications of double inlet left ventricle include the following:
Physical activities are limited.
Frequent pneumonia (lung infection).
Clubbing of fingers and toes (thickening of the nail beds).
Heart rhythm problems.
Heart failure.
How Is a Double Inlet Left Ventricle Diagnosed?
The healthcare specialist recommends various tests to diagnose or confirm a double inlet left ventricle defect. The tests include:
Chest X-ray.
An electrocardiogram (ECG) (to measure the heart's electrical activity).
An echocardiogram (ECHO) (ultrasound is used to provide pictures of the heart).
A cardiac magnetic resonance imaging (MRI).
Cardiac catheterization (a small flexible tube called a catheter is inserted through a blood vessel to examine the functioning of the heart).
How Can the Double Inlet Left Ventricle Be Managed?
Double inlet left ventricle is a complex condition that is challenging to treat. It includes surgery to optimize the blood flow to the lungs and other parts of the body. Surgery is especially required in the first few weeks of life to improve the functioning of the heart.
Certain medications are prescribed by the doctor before and after the surgery, such as anticoagulants (to prevent clotting of blood), Inotropic agents (to help with heart contractions), angiotensin-converting enzyme inhibitors (to reduce blood pressure), and diuretics (water pills to reduce swelling).
The first surgery is performed when the baby is just a few days old, known as the Blalock-Taussig shunt. In this procedure, a small tube called a shunt is used to direct blood flow to the lungs. The baby can be discharged on the same day but must take certain medications, followed by periodic check-ups. The surgeon also determines and informs the parents about when the second stage of surgery needs to be planned.
The second surgery, known as the bidirectional Glenn shunt procedure or Hemi-Fontan procedure, is usually performed when the child is four to six months of age to direct the blood flow from the upper parts of the body to the pulmonary artery that takes it to the lungs without going through the heart.
The third surgery is the Fontan procedure, performed when the child is two to three years old. This surgery allows oxygen-poor blood from the lower parts of the body to the lungs through the pulmonary artery without entering the heart's right ventricle. The procedure does not create normal circulation but prevents the mixing of oxygen-rich and oxygen-poor blood and improves blood flow and circulation in the body, thus allowing the growth and development of the child. A heart transplant may be recommended if all these surgeries are not effective.
Conclusion
Double inlet left ventricle is a rare congenital condition affecting the chambers and valves of the heart. It usually develops in early pregnancy and may be associated with other heart problems. The treatment is challenging and mainly based on the severity of the defect and associated conditions. The child's physical activities may be limited, and periodic evaluation is necessary to avoid future complications. However, many patients live to adulthood due to recent advances in surgical procedures and healthcare technology.
