Truncus Arteriosus is a rare defect of the heart in which a single common blood vessel comes out of the heart, instead of the usual two vessels (the main pulmonary artery and aorta)
PREVALENCE
Truncus arteriosus occurs in less than one out of every 10,000 live births. It can occur by itself or as part of certain genetic disorders e.g DiGeorge syndrome
PATHOPHYSIOLOGY
Truncus is a type of Cyanotic heart disease. This means the body is not getting enough oxygenated blood. This is as a result of blood leaving the heart through a single channel called the truncus (hence the name). Normally blood coming into the heart and that leaving the heart doesn’t mix and this ensures proper oxygenation of the body. In truncus arteriosus, blood from both sides of the heart leaves the heart through a single channel which results in the mixing of blood and reduction in oxygenation of the body. The mixing is further worsened by an abnormal connection between the left and right side of the heart. This is known as a ventricle septal defect (a type of hole in the heart) that is always present and over which the truncus overrides.
CLINICAL FEATURES
This depends on age of the child. Usually at birth cyanosis(bluish discolouration of the body) is mild and as the child becomes older it worsens and the child can develop heart faliure.Abnormal heart sounds known as murmurs can also be heard at different points on the chest depending on the Pathology. A bounding pulse(forceful) and wide pulse pressure can also be observed. Others include Abnormal breathing, poor feeding and extreme sleepiness.
DIAGNOSIS
Can be made before and after birth
Prenatal diagnosis is can be made using maternal ultrasound during antenatal workup and specifically fetal echocardiogram(an ultrasound that looks as the fetal heart)
Postnatal diagnosis can be made with echocardiogram(an ultrasound of the heart) which shows the pathology. Supportive investigation includes chest x-ray, electrocardiogram both of which can show an enlarged heart.
TREATMENT
Medications
Some babies with truncus arteriosus also will need medicines to help strengthen the heart muscle, lower their blood pressure, and help their body get rid of extra fluid.
Nutrition
Some babies with truncus arteriosus might become tired while feeding and might not eat enough to gain weight. To make sure babies have a healthy weight gain, a special high-calorie formula might be prescribed. Some babies become extremely tired while feeding and might need to be fed through a feeding tube.
Prenatal diagnosis
Surgery is needed to repair the heart and blood vessels. This is usually done in the first few months of life. Options for repair depend on how sick the child is and the specific structure of the defect. The goal of the surgery to repair truncus arteriosus is to create a separate flow of oxygen-poor blood to the lungs and oxygen-rich blood to the body and it is best done before the child’s 1st birthday for a greater outcome.
References
- Nelson textbook of paediatric 20th Edition
- Centre for disease control and prevention; https://www.cdc.gov/ncbddd/heartdefects/truncusarteriosus.html