Saturday, August 13, 2005

Abhishek - Patent Ductus Arteriosus

Hi all,

I have been doing rounds in the Neonatal ICU for about 2 weeks now. One of the babies is suffering from a congenital heart disease called Patent Ductus Arteriosus. The ductus arteriosus is a normal fetal structure, allowing blood to bypass circulation to the lungs. Since the fetus does not use his/her lungs (oxygen is provided through the mother’s placenta), flow from the right ventricle needs an outlet. The ductus provides this, shunting flow from the left pulmonary artery to the aorta just beyond the origin of the artery to the left subclavian artery. The high levels of oxygen which it is exposed to after birth causes it to close in most cases within 24 hours. When it doesn’t close, it is termed a Patent Ductus Arteriosus (PDA). Here is a cartoon representation of PDA -

The defect often corrects itself within several months of birth, but may require infusion of chemicals, the placement of "plugs" via catheters, or surgical closure. The flow pattern is similar to the septal defects, except that the shunting occurs outside of the heart. The left ventricle has to pump blood out through the aorta, only to have some of it flow to the lower pressure pulmonary artery, and directly back to the left atrium and ventricle. If a large PDA is not corrected, then the pressures in the pulmonary arteries may become very high and induce changes in the arteries themselves such that even closure of the defect will no longer improve the patient. In this case, the pressures in the right side of the heart are high enough that blood may begin to flow from the right to the left side of the heart. This situation is called "Eisenmenger’s syndrome", a condition which may result from several similar abnormalites. Here is an image showing the location of the PDA in a full size cartoon of the infant heart:

Surgical repair

The type and timing of surgical repair depends on the child's condition and the type and severity of heart defects. In general, symptoms that indicate that surgery is needed are -
  1. difficulty breathing because the lungs are wet, congested, or fluid-filled (congestive heart failure)
  2. problems with heart rate or rhythm (arrhythmias)
  3. excessive work load on heart that interferes with breathing, feeding, or sleeping

An incision may be made through the breastbone (sternum) and between the lungs (mediastinum) while the child is deep asleep and pain-free (under general anesthesia). For some heart defect repairs, the incision is made on the side of the chest, between the ribs (thoracotomy) instead of through the breastbone. Heart-lung bypass may be needed. Tubes are used to re-route the blood through a special pump that adds oxygen to the blood and keeps it warm and moving through the rest of the body while the repair is being done.

Most children need to stay in the Intensive Care Unit for 3 to 7 days and stay in the hospital for 5 to 14 days. By the time the child is transferred out of the intensive care unit, most of the tubes and wires have been removed and he is encouraged to resume many of his daily activities. At the time of discharge, the parents are instructed on activity, how to care for the incision and how to give medications their child may need to take such as Digoxin, Lasix, Aldactone and Coumadin. The child needs at least several more weeks at home to recover.

The baby underwent this surgery and was brought back to Neonatal ICU and remained stable after the surgery. One of the things that I noticed before the surgery took place on this baby was the condition the baby was in before he went into surgery. The team responsible for the baby took great pains to make sure that his breathing was normal and was not sick (otherwise apart from the PDA ofcourse) before he went into the OR.

Images and Illustrations provided by and MedlinePlus Medical Encyclopedia.


Blogger Super Cat said...

Can we say that the Eisenmenger's syndrome in a PDA results only in Differential cyanosis?? Great write-up.. Kudos

1:59 PM  
Blogger Super Cat said...

This comment has been removed by the author.

2:00 PM  

Post a Comment

<< Home