Hypolastic Left Heart Syndrome
Hypoplastic Left Heart Syndrome (HLHS) is a congenital heart defect characterized by the partial or complete failure of the left side of the heart to develop. A normally developed heart is composed of four chambers. The two chambers that collect blood are called the right and the left atria, and the two chambers that pump blood are called the right and left ventricles. When the blood is pumped to the lungs from the right ventricle it returns to the heart via the pulmonary veins to the left atrium. It flows from the left atrium through the mitral valve into the left ventricle. The left ventricle ejects (pumps) blood through the aortic valve into the aorta, and out to the body. With each contraction of the left ventricle all vital organs brain, kidneys, and intestines, are perfused with oxygen rich blood. Children with HLHS have a problem with the development of some, or in most cases, all of the structures on the left side of the heart. In utero the mitral valve, left ventricle and aorta may not form normally. Infants with HLHS fall into a category of congenital heart defects known as “single ventricles”. This simply means that for whatever reason one of the pumping chambers (ventricles) of the heart is hypoplastic (small) or absent.
When a child is born with Hypoplastic Left Heart Syndrome the blood’s journey through the heart is very different from that of a normal heart. When the “blue” or unoxygenated blood comes back to the heart from the body it enters the right atrium. From the atrium it flows through the tricuspid valve into the right ventricle. From the right ventricle the blood is pumped out through the pulmonary valve and the right and left pulmonary arteries to the lungs where it receives oxygen. The “red” or oxygenated blood returns to the left side of the heart via the pulmonary veins, but it is either unable to pass through the mitral valve, or be accepted into the left small left ventricle. Because of the underdeveloped left side, blood will pass from the left atrium to the right atrium through an atrial septal defect. The oxygenated blood will mix with the “blue” blood and part of the blood will follow the normal path to the lungs. Some of the blood, however, will pass to the body through a structure between the main pulmonary artery and the aorta known at the ductus arteriosus. The ductus arteriosus is utilized in the womb, but normally closes shortly after birth when the patient is exposed to oxygen. In children with HLHS the ductus arteriosus must remain open. Blood that cannot be ejected from the left side of the heart must flow from the pulmonary artery to the aorta through the ductus arteriosus in order to perfuse the body. When the baby is born, and its lungs are exposed to oxygen, the ductus can begin to close. If the ductus starts to close, there is a decrease of blood and oxygen into the body, As the process evolves the situation becomes incompatible with life and the child ultimately succumbs to the lack of oxygen delivery to the body. Because it sometimes takes longer for the ductus arteriosus to close on some infants, some newborns with HLHS will go undiagnosed until the ductus arteriosus starts to close. (These children usually become irritable, start to breathe fast and stop eating).
What occurs if Hypoplastic Left Heart goes untreated?
The infant with the diagnosis of Hypolastic Left Heart Syndrome has a 100% mortality rate if left untreated. These infants will have no blood flow to the body once the ductus arteriosus closes. No one can really say when the ductus arteriosus will close. On some infants it closes quickly, on others it may take several weeks to close. Regardless, children born with this lesion who do not receive treatment will die.
What is the treatment for Hypoplastic Left Heart Syndrome?
Three treatment choices exist for the parents of an infant born with HLHS. First choice would be to discontinue medical care and take the infant home; however, when the ductus arteriosus closes the baby will pass away. Nobody can predict when this will happen.
Second choice in the treatment of HLHS would be a heart transplant. Although transplantation is an option, neonatal hearts are hard to come by, and an infant with HLHS may die before a heart becomes available. Another limitation of this choice is that it normally becomes necessary for the family to relocate to the city in which the transplantation center is located. This can be very hard on families and the children themselves.
Third, and probably the most common choice in treatment is to undergo surgical palliation with a Norwood procedure. Infants with HLHS have only three chambers of their hearts that are functioning normally. The goal for these infants must therefore be to preserve the existing anatomy of the heart, to secure a permanent oxygen delivery system for the body, and to decrease the workload of the single ventricle which will serve as the only pumping chamber for the heart. Parents should understand that the Norwood procedure is the first of 3 operations performed over a period of 2-3 years. The surgical treatment for HLHS, as with all “single ventricle” hearts, is not aimed at correcting the abnormal anatomy, but to palliate the patient with their given anatomy.
What is the surgical treatment for Hypoplastic for Hypoplastic Left Heart Syndrome?
The first surgery is done within the first 7-10 days of life. As mentioned, this procedure is known as the Norwood operation. This intervention is the most critical and carries the highest risk of death. As mentioned above, this stage is only palliative.
The Norwood operation has three goals:
1. Establishing a temporary, but reliable pathway of blood flow to the lungs. This is accomplished with one of two types of shunts:
A. Blalock- Taussig shunt. The Blalock- Taussig shunt (systemic to pulmonary shunt), creates a connection between a subclavian artery and usually the pulmonary artery. A synthetic tubular graft (Gortex) is used to connect the patient’s subclavian artery to the pulmonary artery. This shunt will provide a source of blood flow to the pulmonary arteries which will then flow to the lungs.
B. Sano Shunt. The Sano shunt consists of connecting a Gortex tube graft between the single, right ventricle and the pulmonary arteries. Like the Blalock- Taussig shunt, the Sano shunt allow blood flow to the lungs.
2. Reconstruction of the Aorta: This part of the Norwood procedure consists of enlarging the atretic or small native aorta. This is done by utilizing the patient’s own pulmonary artery and ascending aorta, as well as a patch of cryopreserved homograft tissue. At the end of the Norwood operation the child will have a single great artery arising from the heart.
3. Adequate mixing of the Atrial Blood: This is accomplished during the Norwood procedure with an atrial septostomy. This means that the hole between the left and right atria is enlarged. This ensures that blood can flow easily from the left atrium to the right side of the heart (the main pumping chamber).
As mentioned above, the patient with HLHS will require a total of three operations to palliate their heart condition. The Second surgery that a child with HLHS must go through is known as a Glenn procedure, or a Hemi- Fontan. This surgery is usually performed at around 3-4 months. In this surgery the Superior Vena Cava, or the blood vessel that returns blood from the head, neck and arms is directly connected to the right pulmonary artery. This procedure is usually done through a sternal incision. In this procedure approximately 1/3 -1/2 of the blood returning to the right atrium through the venous system is diverted directly to the lungs. Because of gravity a pumping system is not needed to push this blood out to the peripheral lung beds. It is crucial for the pulmonary vascular resistance (pressures in the lungs) to be low for the blood to flow passively in to the pulmonary arteries. For this reason the procedure is performed intentionally at three to four months of age when the infant’s pulmonary pressures drop from the high values present at birth. A cardiac catheterization may be performed prior to this procedure to assess the lung pressures. If the pressures in the lungs are still too high to safely perform the procedure (> 20 mm Hg), then the second stage surgery will be postponed for a few months.
The third and final surgery is usually completed when the child is around two years of age. This surgery is known as the Fontan procedure. The whole premise of the Fontan circulation for children with “Single Ventricle” anatomy is directing the remaining venous circulation (blood from the abdomen and legs), to the pulmonary arteries without going through a pumping chamber. The Fontan also separates the “blue” and the “red” blood circulations. The IVC blood flow is made to flow directly into the pulmonary circulation by means of a tunnel. This tunnel may be created inside the heart (intra-cardiac) or outside the heart (extra- cardiac). A fenestration or “hole” communicating the tunnel to the inside of the right atrium is often left to act as a safety valve in order to allow the pressure in the Fontan circulation to remain low.
What is the survival rate for the Norwood operation?
Currently, the Norwood Stage I survival rate is about at 70% - 80%. If the patient survives the Stage I, the survival rate for stage II, Glenn procedure, increases to about 98%. The survival rate for the completion of the Fontan is around 95%.
What are some of the complications that you may see with the 3 stages of the Norwood?
Norwood:
1. Death
2. Stroke
3. Infection
4. Bleeding/ Blood transfusions
5. Nerve (recurrent laryngeal) injury
6. Need for open chest post-operatively
7. ECMO
Bi- Directional Glenn/ Hemi- Fontan:
1. Death
2. Stroke
3. Infection
4. Bleeding/ Blood transfusions
5. Nerve (recurrent laryngeal) injury
6. Facial Swelling
7. Chylous Effusions
Fontan:
1. Death
2. Stroke
3. Infection
4. Bleeding/ Blood transfusions
5. Nerve (recurrent laryngeal) injury
6. Chylous Effusions
7. Ascites
8. Protein losing diarrhea (late)
Contact Information:
John Mark Morales MD, FACS, FAAP
Chief of Cardiothoracic, Director of Perfusion Services
Certified by the American Board of Surgery, American Board of Thoracic SurgeryMark Bielefeld, MD
Driscoll Children's Hospital Chief of Staff
Certified by the American Board of Surgery, American Board of Thoracic SurgeryThoracic surgeons are available for questions and consultations: (361) 854-0201. For appointments, assistance, and physician references in Corpus Christi call: (361) 854-0201 or 800-DCH-LOVE
Fax : 361-855-7572
E-MAIL : jmarkmorales@aol.com
For further information on any surgical procedures you can contact Carol Kaplan, RN, Surgical Nurse Liaison at (361) 694-5150. Consultation and surgery for inpatients is provided in concert with neonatology and pediatric cardiology departments. Complete evaluation and management for infants, children, adolescents and adults with congenital or acquired cardiac, vascular or thoracic anomalies.
Cardiothoracic Associates
3533 S. Alameda, Suite 202
Corpus Christi, Texas 78411
Phone: (361) 694-5150
Fax: (361) 855-7572
Hours: 9am to 6pm
Fri 9am to 5pm
Statement of Compliance
Voted Best Place to Work in 2006 and 2007 | Ways to Give | Contact Us
Copyright © Driscoll Children's Hospital 2008
Corpus Christi, Texas
You
must have Windows Media Player 10 installed on your computer to view the
videos. Click here to download Windows Media Player 10
Click
here to see Alexxandra Contrera's Miracle Story movie
Click
here to learn about International Services
More
information about
