A GENETIC LINK MAY BE PRESENT. SIBLINGS HAVE HIGHER INCIDENCE.
Contraindications: The primary contraindication to repair is severe pulmonary vascular disease. If transient intraoperative occlusion of the PDA does not decrease elevated pulmonary arterial pressures with a subsequent increase in aortic pressure, then the closure must be undertaken carefully and may be contraindicated. Closure of the ductus does not reverse preexisting pulmonary vascular disease.
A subset of associated cardiac anomalies-so-called ductal-dependent lesions-depend on flow through the PDA to maintain systemic blood flow. Premature closure of the ductus without concurrent repair of the following defects is contraindicated and may be fatal:
" Pulmonary artery hypoplasia
" Pulmonary atresia
" Tricuspid atresia
" Transposition of the great arteries
" Aortic valve atresia
" Mitral valve atresia with hypoplastic left ventricle
" Severe coarctation of the aorta
Medical therapy: Infants with signs of failure may be treated initially with digoxin and diuretic therapy, but interruption of the ductus is required for definitive treatment.
" Preterm infants: Indomethacin (Indocin) has proven efficacious resulting in twice the spontaneous closure rate. However, the ductus may reopen days or weeks later.
" Interventional radiology: Several techniques to occlude the patent ductus arteriosus (PDA) are available, although definitive closure rates do not approach those of surgery.
" Gianturco coils: Introduced in 1992, these coils are delivered to the PDA via venous or arterial systems. One to 5 coils are placed in the ductus. This method has been reported to be 75-100% effective but is limited to ductus that are only 4-5 mm in diameter.
" Rashkind ductus occlusion device: This consists of a 2-umbrella system delivered to the ductus in either the transvenous pathway or transarterial pathway. This therapy has a reported occlusion rate of 83%. Although used internationally, it is not approved for use in the United States.
Surgical therapy: Surgery is the mainstay of treatment for PDA. If an infant has failed to thrive or has overt congestive heart failure, the ductus should be interrupted, regardless of age and size. If the patient is asymptomatic, elective ligation and division can be carried out at approximately age 4 years when the risks of intubation are decreased and the child is more capable of understanding the procedure and process. Some authorities recommend closure any time after age 12 months or when the patient becomes symptomatic.
The operative approach is performed using a left lateral posterior thoracotomy with the patient under general anesthesia. In small children, the incision can be limited to several centimeters. The thorax is entered through the third intercostal space in the infant and the fourth intercostal space after infancy. The PDA is identified, dissected, and doubly ligated. The earliest procedures involved double clamping of the ductus and oversewing each end. While this is still a definitive approach, it is not used nearly as frequently because division is not considered to be an essential part of the closure, and clamping can be risky when the ductal tissue is friable.
A chest tube is usually placed intraoperatively and removed after 24 hours if no air leak ensues. The typical hospital stay is 3-4 days; however, newer studies report average stays of less than 2 days when using the muscle-sparing thoracotomy through an axillary approach or other less invasive incisions.
Preterm neonates
For neonates weighing 500-1200 g, the procedure is easily accomplished in the neonatal ICU under simulated operating room conditions. A 1.5-cm incision based posteriorly near the tip of the scapula is made with the child in the right lateral decubitus position. The lung is retracted medially, and the mediastinal pleura over the descending aorta and proximal subclavian artery is incised and retracted medially. This allows good visualization of the ductus and all important associated structures.
Vascular forceps may, on rare occasions, be used to occlude the structure thought to be the ductus if any doubt exists. At this juncture, the distal pulse oximeter and systemic pressure measurements can be used to confirm proper identification of the PDA. Again, this is rarely necessary. Two or more Hemoclips can then be used to close the duct. Dividing the duct in these critical neonates is usually not advisable. Operating in the neonatal ICU is important because these neonates are often in unstable, ventilator-dependent conditions that make transportation to the operating room more dangerous.
Overall benefits of early ligation or medical treatment in regard to decreased bronchopulmonary dysplasia, hospital costs, and mortality rates are unclear. The timing of duct closure is also somewhat controversial, but closure is often recommended when indomethacin therapy fails or is contraindicated in patients with subarachnoid hemorrhage or renal failure. While definitive data are not available, many aggressive neonatologists believe that early ligation of the ductus is an important adjunct in weaning these premature neonates from the ventilator.
Adults with calcified PDA
Cardiopulmonary bypass (CPB) is often necessary to safely close these communications because calcification may preclude ligation and the tissue may fracture, resulting in uncontrolled hemorrhage. A median sternotomy incision provides excellent exposure. The ductus can be patched through an incision in the pulmonary artery under low-flow conditions or after a balloon catheter is passed through the communication to prevent vigorous bleeding from the aorta during closure. An identical approach can be used for aneurysmal communications and may even require deep hypothermia with circulatory arrest to gain the necessary control and exposure.
Thoracoscopy - Minimally invasive surgery
Thoracoscopy provides an alternative to left posterior thoracotomy. It has been proven useful in both infants and adults. Whether thoracoscopy has benefits over muscle-sparing thoracotomy is debatable. It is not clear if thoracoscopy provides shorter hospital stays or decreases costs. Additionally, thoracoscopy is contraindicated for adults with calcified PDA. Its use in neonates is not widely advocated secondary to limited control and visualization, and it has no definite advantage since the open procedure uses such a small incision.
Intraoperative details:
Infants
For PDA repair in the infant, either an operating room or a portable operating room in the neonatal ICU may suffice. The patient is prepared and draped in the right lateral decubitus position with the left arm extended above the head. Normothermia and proper attention to ventilation are imperative, especially in neonatal patients. The various incisions used are described above.
The left lung is retracted medially, taking care not to compromise ventilation or cardiac output any more than necessary. Meticulous dissection is performed as previously described, taking great care to identify the subclavian artery, descending aorta, distal arch, and ductus prior to performing any ligation, since catastrophic mistakes are easier to make than an inexperienced surgeon might imagine. The surgeon must make every effort to identify and preserve the left recurrent laryngeal nerve.
Once accurate identification of the patent ductus is made, it is isolated and ligated with either silk suture or stainless steel clips, depending on the size of the ductus. Several ties or clips are used since more than a single tie greatly reduces the chance of recanalization. Closing the mediastinal pleura is not necessary after most procedures. A chest tube may be placed at the end of the procedure; however, this step can often be safely omitted, depending on the surgeon's preference.
Adults
Many adolescent and adult patients can be approached via a standard left thoracotomy, much like younger patients. However, when the ductus is large, some risk may be present with simple ligation, including tearing and hemorrhage. In these cases, gentle double clamping with appropriate vascular clamps and division with oversewing using 4-0 Prolene suture is indicated. Because the PDA tends to be short and can be calcified at the aortic end, repair in adults may require a median sternotomy and CPB.
After preparation for CPB is complete, the aorta and pulmonary trunk are separated. Single venous cannulation is sufficient. After CPB is established and the heart is emptied, the patient is placed in the moderate Trendelenburg position, and the PDA is manually occluded by compressing the front wall of the left pulmonary artery against it. This maneuver prevents distension of the pulmonary vasculature and right ventricle.
The aorta is cross-clamped, and cardioplegia is infused to arrest the heart. Manual occlusion of the PDA is removed, and the pulmonary artery is opened opposite the PDA. Temporary low-flow perfusion is used while the blood from the duct is blocked with a balloon catheter or finger occlusion. Pledgeted 4-0 or 3-0 Prolene sutures are used to definitively close the ductus. In the rare cases in which the orifice is too large for this closure, a synthetic patch of Dacron or polytetrafluoroethylene can be sewn in. The pulmonary artery is closed with a running Prolene suture, and CPB is terminated in routine fashion after full rewarming. Mediastinal chest tubes are placed and may be routinely removed the morning following the operation.
Follow-up care: Timely closure of a PDA is generally definitive treatment, and no special care or follow-up is necessary. While rare reports exist of recanalization and recurrence of a left-to-right shunt after PDA ligation, the risk is extremely low.
If a PDA has been closed by interventional radiologic techniques, obtaining follow-up echocardiograms until complete closure is confirmed is wise.
COMPLICATIONS :
Complications may include the following:
" Incomplete closure or recanalization
" Bleeding
" Pneumothorax
" Injured recurrent laryngeal nerve
" Chylothorax as a result of thoracic duct injury
" Rare ligation of nonductal tissue
OUTCOME & PROGNOSIS :
The prognosis is generally considered excellent in patients in whom the patent ductus arteriosus (PDA) is the only problem. In premature infants who have other sequelae of prematurity, these sequelae tend to dictate prognosis of PDA. In the adult patient, prognosis is more dependent on the condition of the pulmonary vasculature and the status of the myocardium if congestive cardiomyopathy was present prior to ductal closure. Patients with minimal or reactive pulmonary hypertension and limited myocardial changes may have a normal life expectancy.
DRUG TREATMENT :
1. INDOMETHACIN : USED SUCCESSFULLY TO CLOSE A PDA IN LARGE PROPORTION OF PREMATURE INFANTS. NOT EFFECTIVE IN TERM BABIES.
β’ Ibuprofen 10mg/kg on day 3 of life, 5mg/kg/day for 2 days.
2. INFANTS WITH SIGNS OF CHF CAN BE MANAGED FOR SHORT TERM WITH ANTICONGESTIVE MEDICINES LIKE DIURETICS & OXYGEN BUT STANDARD TREATMENT IS SURGERY.
3. PT WITH PDA SHOULD RECEIVE BACTERIAL ENDOCARDITIS PROPHYLAXIS ACCORDING TO RECOMMENDED AHA GUIDELINES.
ALTERNATIVE DRUGS
β’ Indomethacin 0.2-0.25 mg/kg/dose IV preferred. Repeat every 12-24 hours x 3 doses. (Decreased efficacy in term infants; not effective in children or adults.)
β’ Alprostadil
PATIENT MONITORING
β’ Annual, routine followup after closure
β’ Shunts that have not been closed should be followed more closely
POSSIBLE COMPLICATIONS
β’ Left heart failure
β’ Pulmonary hypertension
β’ Right heart hypertrophy and failure
β’ Eisenmengerβs physiology
β’ Bacterial endocarditis
β’ Myocardial ischemia
β’ Necrotizing enterocolitis
EXPECTED COURSE/PROGNOSIS
β’ Spontaneous closure after 3 months is rare
β’ Before 3 months, closure in premature infants is 75%
β’ Before 3 months, closure in term infants is 40%
β’ Best postoperative results if closed before age 3 years
β’ Increased pulmonary vascular resistance and pulmonary hypertension more common if closed after age 3
years
β’ No firm statistics but decreased survival for large shunts