Hypoplastic left heart syndrome

Hypoplastic left heart syndrome. The condition is congenital (it is present at birth). The hypoplastic left heart is a rare type of congenital heart disease and is more common in men than in women.

Table of Contents

Summary

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1 Causes, incidence and risk factors
2 Symptoms
3 Signs and tests
4 Treatment
5 Forecast
6 Complications
7 Source

Causes, incidence and risk factors

As with most congenital heart defects, there is no known cause. About 10% of patients with this syndrome will also have other birth defects. The problem develops before birth when there is insufficient growth of the left ventricle and other structures, including:

The aorta, the blood vessel that carries oxygenated blood from the left ventricle to the entire body.
Exit and entry of the ventricle.
Aortic and mitral valves.

This leads to incomplete or hypoplastic development of the left ventricle and aorta. In most cases, the left ventricle and aorta are much smaller than normal. In patients with this condition, the left side of the heart is unable to send enough blood to the body. As a result, the right side of the heart must maintain both pulmonary and body circulation. The right ventricle can maintain circulation to both the lungs and body for a time, but this work overload eventually leads to heart failure.

The only chance for survival is a connection between the left and right sides of the heart or between its arteries and the pulmonary arteries (the blood vessels that carry blood to the lungs). Babies are normally born with two of these connections:

The oval hole (a hole between the left and right atrium).
The arterial duct (a small blood vessel that connects the aorta to the pulmonary artery ).

Both connections normally close on their own within a few days after birth. In babies with hypoplastic left heart syndrome, blood from the right side of the heart travels through the arterial duct. This is the only way for blood to reach the body. If the arterial duct is allowed to close in a baby with hypoplastic left heart syndrome, the patient can die quickly, because there will be no pumping of blood to the body. Babies with this syndrome are usually started on medicine to keep the arterial duct open.

Because there is little or no circulation to the left side of the heart, the blood that returns to the heart from the lungs needs to pass through the foramen ovale or inter-atrial communication (a hole that connects the collecting chambers on the left and right sides of the heart). heart) back to the right side of the heart. If there is no oval hole or if it is too small, the baby could die. For patients with this problem, the hole between the atria is opened, either with surgery or using cardiac catheterization.

Symptoms

Initially, a newborn with a hypoplastic left heart may appear normal. Symptoms usually appear in the first hours of life, although it may take up to a few days for them to develop, and some of them may be:

Bluish skin ( cyanosis ) or a bad color.
Cold hands and feet (extremities).
Weak pulse.
Poor diet and lactation.
Pounding heartbeat
Fast breathing.
Breathing difficulty.

In healthy newborns, bluish skin occurs on the hands and feet in response to the cold (this reaction is called peripheral cyanosis). However, the bluish color seen in the chest or abdomen, on the lips, and on the tongue is abnormal (called central cyanosis) and is a sign that there is not enough oxygen in the blood. Central cyanosis often increases with crying.

Signs and tests

A physical exam may show signs of heart failure :

Heart rate faster than normal.
Hepatomegaly .
Fast breathing.

Also, the pulse may be very weak at various locations (wrist, groin, and other places). Upon auscultation of the chest , there are usually (although not always) abnormal heart sounds.

Exams may include:

Cardiac catheterization.
Chest x – ray .

Treatment

Once the diagnosis of hypoplastic left heart is made , the baby is taken to the neonatal intensive care unit (NICU), and a respirator (breathing machine) may be needed to help him breathe. Also, a medicine called prostaglandin E1 is used to maintain blood circulation to the body, keeping the arterial duct open. These measures do not solve the problem, since the condition always requires surgery.

The first surgery, called the Norwood procedure, is performed in the baby’s first days of life. Stage I of this procedure is to build a new aorta:

Using the valve and pulmonary artery.
Connecting the old hypoplastic aorta and the coronary arteries to the new aorta.
Removing the wall between the atria (atrial septum).
Making an artificial connection from either the right ventricle or a body artery to the pulmonary artery to maintain circulation to the lungs (called a shunt)

After this, the baby usually leaves the hospital for home. The child will need to take daily medications and should be closely followed by a pediatric cardiologist, who will determine when the second stage of surgery should be performed.

The second stage of the surgery is called a Glenn shunt or Hemifontan procedure. This procedure connects the largest vein that carries blue blood from the upper half of the body (superior vena cava) directly to the blood vessels that go to the lungs (pulmonary arteries) to obtain oxygen.. This surgery is usually done when the child is between 4 and 6 months old. During stages I and II, the child may still appear somewhat bluish (cyanotic). Stage III, the final step, is called the Fontan procedure. The rest of the veins that carry blue blood from the body (inferior vena cava) connect directly to the blood vessels that go to the lungs. The right ventricle now serves only as the pumping chamber for the body (no longer the lungs and the body). This surgery is usually carried out when the baby is between 18 months and 3 years old. After this last step, the baby will no longer turn blue.

Some patients may need more surgeries when they reach their 20s or 30s if they have difficult to control arrhythmias or other complications from the Fontan procedure. In some hospitals, they consider a heart transplant a better option than the 3-step surgical process, but there are few donated hearts available for young children.

Forecast

Without treatment, hypoplastic left heart syndrome is fatal. Survival rates for staged repair continue to increase as surgical technique and postoperative management improve. Survival after the first stage is over 75%. The size and function of the right ventricle are important in determining the child’s prognosis after surgery.

Complications

Complications include:

Artificial shunt obstruction.
Diarrhea chronic (from a disease called enteropathy loss of protein ).
Fluid in the abdomen (ascites) and in the lungs (pleural effusion).
Heart failure .
Fast and irregular heart rhythms (arrhythmias).
Strokes and other neurological complications.
Sudden death.