Hypoplastic Left Heart Syndrome

Hypoplastic Left Heart Syndrome (HLHS)

Hypoplastic left heart syndrome occurs when parts of the left side of the heart (mitral valve, left ventricle, aortic valve, and aorta) do not develop completely. The left ventricle is nonfunctional. Thus the left side of the heart is completely unable to supply blood to the systemic circulation.

The condition is present at birth (congenital).It is a duct dependent lesion (systemic flow depends upon patency of ductus).

HLHS is the 4th most common congenital heart defect. Occurs in up to 4% of cases of CHD. (Miyamoto et al, 2011)

In patients with HLHS, 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 the circulation for both the lungs and the body. Blood returning from the lungs into the left atrium must pass through an ASD to the right side of the heart. The right ventricle must then pump blood to the lungs and also to the systemic circulation through the PDA.

Pathophysiology

A few days after birth when the ductus arteriosus closes, the heart cannot pump blood into the systemic circulation, causing poor perfusion of the vital organs & shock. Death will occur rapidly without intervention.The right ventricle can support the irculation to both the lungs and the body for a while, but this extra workload eventually causes the right side of the heart to fail.

Pathophysiology contd…

The only possibility of survival is a connection between the right and left side of the heart.

Coronary arteries are filled by retrograde flow from ductus through the hypoplastic ascending aorta.

Pathophysiology contd…

The neonates are born healthy, no cyanosis, no murmur. But after some hours to a day or two, the infant becomes critically ill & may die due to closure of ductus.

Cyanosis, irritability, low volume pulse with hypotension, RV impulse, single heart sound and no murmur.

Clinical manifestations

Health history: Onset of cyanosis, Poor feeding, History of tiring easily.

Physical examination: Evaluate vital signs noting tachycardia, tachypnea, & hypothermia. Observe for increased work of breathing and gradually increasing cyanosis. Note pallor of the extremities.

Health history & Physical examination

Pulse oximetry: shows decreased oxygen saturation. Auscultation of the heart & lungs: adventitious breath sounds, a gallop rhythm, a single second heart sound, and a soft systolic ejection or holosystolic murmur.

Prenatally, a fetal echocardiogram can diagnose this syndrome, as can a maternal ultrasound. After birth, the echocardiogram illustrates the defect.

Diagnostic measures

-Once the diagnosis of hypoplastic left heart is made, the baby will be admitted to the neonatal intensive care unit.

-A ventilator may be needed to help the baby breathe.

-Prostaglandin E1 is used to keep the ductus arteriosus open.

Management

Medical Management

-Surgery is done by staged reconstructive approach.

-The first surgery, called the Norwood operation, occurs within the baby’s first few days of life. Stage I of the Norwood procedure consists of building a new aorta by :- using the pulmonary valve and artery

Surgical Management

- connecting the hypoplastic old aorta and 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- wide artery to the pulmonary artery to maintain blood flow to the lungs (called a shunt).

Afterwards, the baby usually goes home. The child will need to take daily medicines and be closely followed by a pediatric cardiologist, who will determine when the second stage of surgery should be done.

Stage II of the operation is called the Glenn shunt or hemi- Fontan procedure. This procedure connects the superior vena cava directly to pulmonary arteries to get oxygen. The surgery is usually done when the child is 4 to 6 months of age.

During stages I and II, the child may still appear somewhat blue(cyanotic).

Stage III, the final step, is called the Fontan procedure, in which the inferior vena cava is connected directly to the pulmonary arteries. The right ventricle now serves only as the pumping chamber for the body. This surgery is usually performed when the baby is 18 months to 3 years old. After this final step baby is no longer blue.

Some patients need more surgeries in their 20s or 30s if they develop hard to control arrhythmias or other complications of the Fontan procedure.

In some hospitals, heart transplantation is considered a better choice than the three step surgery process. However there are few donated hearts available for small infants.

Preoperatively administer prostagland in infusion to prevent closing of the ductus arteriosus. After palliative repairs, monitor for dysrhythmias or worsening ventricular function.

Nursing management

If left untreated, hypoplastic left heart syndrome is fatal. Survival rates for the staged repair continue to rise as surgery techniques and care after surgery improves. Survival after the first stage is more than 75%.

The child’s outcome after surgery depends on the size and function of the right ventricle.

Prognosis

Thank You…

Deepa Merin KuriakoseAssistant Professor

Govt. College of Nursing, Kottayam