The term hypoplastic left heart syndrome is used to describe a severely underdeveloped left heart and several other associated severe heart defects in newborns, most commonly involving the mitral and aortic valves. Survival after birth in these children is initially dependent on maintaining the prenatal short circuit between the pulmonary and systemic circulation via the ductus arteriosus and foramen ovale. This allows the right ventricle to take over the function of the left ventricle to some degree.
What is hypoplastic left heart syndrome?
Hypoplastic left heart syndrome (HLHS) is characterized as a main feature by a severely underdeveloped anlage of the left ventricle (heart chamber) in newborns. The left ventricle sometimes reaches only the size of a pea and therefore inevitably remains non-functional. HLHS is associated with other serious valvular defects and usually with a hypoplastic malformation of the initial part of the aorta up to and including the aortic arch. The aorta normally arises from the left ventricle. The survival of a newborn with HLHS is initially dependent on maintaining the short circuit between the systemic and pulmonary circulation. It is present prenatally and is gradually closed only after birth with release of the pulmonary circulation with the first breath. The malposition of the left ventricle usually also causes a malposition with loss of function of the mitral and aortic valves. In a healthy heart, the mitral valve provides the connection between the left atrium and the left ventricle, and the aortic valve prevents backflow of blood from the aorta into the left ventricle during the relaxation phase of the ventricles, diastole.
Causes
The causes for the occurrence of hyperplastic left heart syndrome are not (yet) clearly understood. Many lines of evidence, especially a familial clustering, suggest causation by genetic defects. Other factors such as drug use or alcohol abuse, which are also suspected, have not yet been proven. Bacterial or viral infectious diseases suffered by women during pregnancy are also obviously ruled out as causative agents of HLHS. Of all congenital heart defects, hypoplastic left heart syndrome accounts for about two to nine percent, depending on the author.
Symptoms, complaints, and signs
Children born with hypoplastic left heart syndrome typically show few symptoms at first. This is because their circulation is not much different from that of healthy babies during the first few days of life. The still open ductus arteriosus, which connects the pulmonary and systemic circulations, causes the oxygen-rich and oxygen-poor blood of the two circulations to mix. Only in rare cases do newborns with HLHS develop early blue discoloration (cyanosis) due to lack of oxygen. Only when the ductus arteriosus closes does relief occur in healthy babies, while HLHS babies are thereby placed in acute oxygen deprivation because blood pumped from the right ventricle into the pulmonary circulation can no longer reach the systemic circulation. Within the first two days of life, affected babies develop respiratory distress syndrome with rapid and labored breathing and shortness of breath. Very rapid fatigue sets in, and the newborns’ performance is severely reduced.
Diagnosis and course of the disease
Important initial and simple diagnostic tools when the presence of hypoplastic left heart syndrome is suspected are listening to heart sounds with a stethoscope and measuring oxygen saturation, in addition to measuring pulse, blood pressure, temperature, and respiratory rate. The electrocardiogram (ECG) and, above all, ultrasound examinations provide information about cardiac function. A chest x-ray provides clarity about the location and size of the heart. In exceptional cases, magnetic resonance imaging (MRI) or cardiac catheterization becomes necessary. The course of the disease in all known forms leads to death within a few days if left untreated, when the ductus arteriosus closes “properly” so that there is no longer any connection between the lungs and the systemic circulation. The right ventricle can then no longer supply the systemic circulation with blood.After successful surgery in several, staggered, steps, life expectancy is good. Except for competitive sports, an almost normal life can be led.
Complications
Left heart syndrome causes a very serious complication, which, if left untreated, leads to the death of the child. Artificial maintenance of body functions is usually necessary for the patient to survive with this condition. As a rule, there are no particular complaints or symptoms in the first few days. Furthermore, however, the skin may turn blue due to the undersupply of oxygen. This undersupply also has a negative effect on the patient’s internal organs and can whitewash them. This leads to shortness of breath and furthermore to shortness of breath. The patient’s ability to cope with stress decreases enormously. The lack of oxygen can also lead to loss of consciousness or coma. Without treatment, the patient will eventually die. Complications can be avoided by early diagnosis and treatment. Surgical intervention is usually necessary, but it is successful and resolves the symptoms. Life expectancy is restored to normal by the operation. Usually, the patient can lead an ordinary life, although certain sports may not be performed.
When should you see a doctor?
If a newborn’s skin turns blue, a doctor should be seen immediately. The blue coloration indicates a lack of oxygen in the organism. Without medical attention, the infant is at risk of premature death. If acute oxygen deficiency develops, the emergency physician must be called. Immediate intervention is necessary in case of respiratory distress, respiratory arrest or gasping for breath. First aid measures must be taken to ensure that the newborn child survives this acute condition. If abnormalities in breathing occur within the first two days after birth, a doctor should be consulted. If the child is hospitalized, the nursing staff should be informed of the observations as soon as possible. If the breathing rate increases, the baby requires significantly more force to breathe, or if breathing seems difficult overall, a doctor must be called. If the baby shows a lowered level of performance compared directly to infants of the same age, a doctor should be consulted. A visit to the doctor is also necessary if the newborn has an unusually strong need for sleep as well as shows renewed signs of fatigue very quickly after a longer period of sleep. If the child becomes apathetic, the muscle tension decreases or if conspicuous movement restrictions are apparent, a doctor should be consulted. Clarification of the symptoms is necessary to prevent a collapse.
Treatment and therapy
The only effective method of treatment is a multistage operation. The first and most important goal is to maintain the connection between the pulmonary and systemic circulation, which is still present at birth, so that the right ventricle can supply the body with mixed blood. In the surgical method according to Norwood, the pulmonary artery is connected to the surgically reconstructed ascending part of the aorta, and the supply of the pulmonary circulation is established through the so-called Blalock-Taussig shunt. In a later second operation (Norwood 2), the right pulmonary artery is connected to the superior vena cava. This allows the pulmonary circulation to be supplied with blood and oxygenated quasi-passively by the pressure in the venous part of the circulation. In this second operation, the previously inserted Blalock-Taussig shunt is removed again. In a third operation, the inferior vena cava is also connected to the pulmonary arteries. This ensures that all venous blood from the systemic circulation enters the pulmonary circulation and the right heart takes over the supply of the systemic circulation.
Prevention
Preventive measures that might prevent hypoplastic malformation of the left ventricle are not known. Because there is no firm evidence on whether drug use or alcohol abuse can cause hypoplastic left ventricular anomaly, abstinence from drugs, alcohol, and cigarettes is generally recommended but cannot prevent the occurrence of HLHS. If the condition has already been identified in family members, a diagnosis can be made in a prenatal ultrasound examination.In the positive case, the birth should then be transferred to a specialized pediatric hospital, which can perform the necessary interventions after birth.
Aftercare
Treatment of hypoplastic left heart syndrome is followed by individualized aftercare, most of which addresses artificial ventilation and feeding. During this process, infants respond positively to the presence and loving attention of their parents. Following therapy, the children often succeed in leading a relatively normal life after an initially difficult phase. However, regular medical examinations are necessary throughout the child’s life in order to detect any problems that may arise in good time. Depending on the individual case, the doctor’s recommendations may lead patients to refrain from strenuous sports. This helps to avoid overstressing the cardiovascular system. In connection with the disease, there are as yet no prophylactic measures that have been medically proven. However, it is useful to avoid drugs and alcohol, even if there is no known direct link. If the disease has previously run in the family, parents should have a prenatal examination. If the diagnosis is positive, they can act quickly and register for the due date at a specialized clinic. Here, everything is already prepared for the necessary interventions shortly after the birth. A certain amount of caution and a health-conscious lifestyle quickly become a habit for the family and the patients themselves.
This is what you can do yourself
Hypoplastic left heart syndrome affects newborn infants who are not capable of self-help measures. Therefore, in the disease, parents or guardians play the essential role in promoting the prospect of recovery as well as the patient’s quality of life. It is crucial for a positive outcome of the disease that the parents observe the newborn child closely and contact a physician immediately in case of any abnormalities during the first days of life. If the parents fail to seek emergency medical care or if it is provided too late, the baby usually dies. The newborn suffers from a blue discoloration of the skin due to hypoplastic left heart syndrome, which indicates the lack of oxygen. Furthermore, the physical well-being of the infant patient is tremendously affected by respiratory distress. When such observations are made, parents immediately call an emergency physician and keep the child alive by first aid measures. In the hospital, the patient receives artificial respiration and nutrition, and the presence of the parents usually has a positive effect on the infant’s condition. If the therapy is successful, the child is usually capable of a normal life, although lifelong control examinations with the doctor must be perceived. Some patients refrain from special sports because of medical instructions, so as not to overload the circulatory system.
