Summary of corrective surgery for Patent Ductus Arteriosus

A patent ductus arteriosus is a congenital defect that occurs when the ductus arteriosus which connects the descending aorta and left pulmonary artery does not close. While it is an important structure in the foetus, after birth if it fails to close it can cause significant pathology. A continuous machinery murmur will be heard in patients with a PDA. The treatment of choice in small animals is ductus arteriosus ligation, which is considered to be curative.


Once anaesthetised prepare the dog for surgery by clipping up the thorax extending to mid abdomen, and to midway up chest wall. Clean the area using chlorhexidine, starting at the center and moving outwards. Follow up with iodine wash again moving from the centre to the outside.


Transport patient into surgery and position patient on right side in lateral recumbency for a left 4th intercostal thoractomy.


Scrub in using sterile procedures. Drape the patient using quarter drapes, secure the field drapes with backhaus towel clamps inorder to securely isolate the unprepared portion of the patient. Now place a large drape over the animal and surgical table to complete the sterile field.


Incise the skin, subcutaneous tissue and cutaneous trunci above 4th intercostal space running from the just ventral to the base of the vertebral bodies to just dorsal to the sternum. Using scissors incise through the latissimus dorsi muscle, and then transect the scalenus and pectoral muscles perpendicular to their fibres. Separate the serratus ventralis fibres above the intercostal space. Using scissors cut the external and then internal intercostal muscles near the costochondral junction.


You are now about to enter the thoracic cavity, so alert the anaesthetist to being ventilating the patient once the pleura is breached. Using blunt scissors penetrate the pleura. Now taking care to avoid the internal thoracic vessels extend the incision dorsally and ventrally to allow greater access to the thoracic cavity. Drape the edges of the incision with moistened labarotomy sponges and use a finochietto retractor to separate the ribs. The ribs will spread more easily cranial to the intercostal incision.


Now locate the heart in the thoracic cavity. Once this is done identify the left vagus nerve as it courses over the ductus arteriosus between the aorta and main pulmonary arteries. Isolate the vagus using sharp dissection as secure it away from the ductus arteriosus using a suture to gently retract it (watch for vagal induced bradycardia, or other vagus associated responses). Without entering the pericardial sac bluntly dissect around the PDA, right angled forceps are often useful for ispolating hte caudal and cranial aspects of the ductus. Pass the forceps from medial to the ductus in a caudocranial direction and grasp a piece of non-absorbable suture (heavy silk No. 1 or 0 is ideal). Slowly pull the suture beneath the ductus, repeat this again do not secure the suture. Now pass a second suture using the same technique. Now slowly tighten the suture closest to the aorta, and next the second suture closer to the pulmonary arteries. The ligation of the PDA is now complete.


Close the thoracic cavity by placing heavy non-absorbable suture around the ribs adjacent to the incision, but do not tie. Using a rib approximator, apose the ribs, now secure the pre-placed sutures. Remove the rib approximator. Suture first the serratus venetralis, then scalenus and pectoralis muscles using a continuous suture pattern in absorbable suture material. Now appose and continuously suture the edges of latissimus dorsi muscle. Remove any residual air from the thoracic cavity using an over-the-needle catheter. Close the subcutaneous tissue and skin using either a continuous or interrupted suture pattern.