SECTION IV - PATENT DUCTUS ARTERIOSUS

Part I - Background Information

The ductus arteriosus, in utero, connects the proximal left pulmonary artery to the descending aorta, just distal to the left subclavian artery. Failure of closure at birth represents a congenital malformation. A PDA in adult is usually an isolated lesion.

Clinical Severity Grading of Patent Ductus Arteriosus (PDA) in Adults

Silent:	Tiny PDA detected only by non-clinical means (usually echo).
Small:	Audible continuous murmur. Causes negligible hemodynamic change. Normal LV size without any pulmonary hypertension.
Moderate:	Audible continuous murmur. Wide pulse pressure (as in aortic regurgitation). Causes enlargement of the left ventricle and some pulmonary hypertension (usually reversible).
Large:	Usually does not exist in adults without Eisenmenger physiology.
Eisenmenger:	Continuous murmur is absent. Causes substantial pulmonary hypertension, differential hypoxemia, and often differential cyanosis.

 
Part II - History and Management of Unoperated Patients

The risk of endarteritis with small silent PDA is unknown but is likely very low (only sporadic case reports exist).

No intervention is indicated if a small silent PDA is detected.
Grade: Consensus

All other PDAs are associated with a risk of endarteritis (which may increase with increasing age).

Small PDAs have a normal life expectancy.

A moderate PDA is unusual in the adult. It is associated with the development of left heart dilation and shunt-related pulmonary hypertension (which often reverses with correction of the defect). The majority of patients are symptomatic from dyspnea or palpitations (atrial arrhythmias), although frank heart failure is unusual.

A large PDA is rare in the adult, most having been corrected in infancy and childhood. Pulmonary hypertension is usual and may not reverse entirely with closure of the defect. Most patients are symptomatic from dyspnea or palpitations. Aneurysm formation of the duct is an uncommon but important complication.

Eisenmenger PDA has a similar prognosis to Eisenmenger VSD although symptoms may be less marked and exercise tolerance better. Eisenmenger PDA is further discussed in section XV.

 
Part III - Diagnostic Recommendations

An initial diagnostic workup:

• Documents the presence of PDA.
• Determines the size (systemic-to-pulmonary shunt estimate) and functional importance (pulmonary artery pressures) of the defect. Shunt estimates are often inaccurate because of the difficulty in obtaining a representative pulmonary blood sample for saturation assessment.
• Identifies whether a ductal aneurysm is present.
• Identifies whether the duct is calcified if surgical repair is planned.

The diagnostic work up should include at a minimum:

• A thorough clinical assessment.
• ECG.
• Chest x-ray.
• Transthoracic echo-Doppler evaluation by an appropriately trained individual.
• Oximetry (obtained on both fingers and toes).

The diagnostic workup may require:

• Heart catheterization (to determine pulmonary artery pressures and resistances with testing of pulmonary vascular reactivity using prostacyclin, inhaled oxygen and nitric oxide if pulmonary arterial pressures are greater than 2/3 systemic).
• Coronary angiography in patients at risk for coronary artery disease or in patients over 40 years if a surgical repair is planned.
• Open lung biopsy should only be considered when the reversibility of the pulmonary hypertension is uncertain from the hemodynamic data. It is potentially hazardous and should be done only at centres with substantial relevant experience in CHD.
• MRI or CT scan to define the anatomy and detect ductal aneurysm or calcification. MRI can also be used to estimate Qp/Qs.

 
Part IV - Indications for Intervention

The following situations warrant intervention: The presence of a PDA (except the silent duct at one extreme and the presence of severe, irreversible pulmonary vascular disease at the other extreme). Closure of a small but audible PDA is usually recommended although this indication remains controversial given the low perceived risk of endarteritis. The occurrence of an episode of endarteritis on a clinically silent PDA. If pulmonary hypertension is present (PAP > 2/3 SABP or pulmonary arteriolar resistance exceeds 2/3 systemic arteriolar resistance), there must be a net left-to-right shunt of at least 1.5:1, or evidence of pulmonary artery reactivity when challenged with a pulmonary vasodilator (e.g. oxygen, nitric oxide, and/or prostaglandin ) or lung biopsy evidence that pulmonary arterial changes are potentially reversible (Heath Edwards grade ll-III or less).
Grade: C	Level: V	Refs: 25,43,44

 
Part V - Surgical/Interventional Technical Options

Device closure is the preferred method for the small ductus and when possible, should be planned at the same time as the diagnostic catheterization. The presence of ductal calcification increases surgical risk and favours device closure.
Grade: C	Level: V	Refs: 45,46

Surgical closure should be reserved for those in whom the PDA is too large for device closure. Examples in which the ductal anatomy may be so distorted as to not be acceptable for device closure might include aneurysm or post-endarteritis. Operative repair should probably be undertaken by congenital heart surgeons.
Grade: Consensus		Refs: 47,48

 
Part VI - Surgical/Interventional Outcomes

Device closure.

Successful closure is achieved in the large majority of attempts using a variety of devices. (45,49,50) More than 85% of ducts are closed by one year following device placement. In a small proportion of patients, a second or even a third device may need to be placed. This is usually deferred for at least 6 months. Recanalization is rare but can occur.

Surgical closure.

More than 95% of ducts can be closed by surgery. Recanalization is unusual but recognized.
Postoperative complications may include recurrent laryngeal or phrenic nerve damage and thoracic duct damage.

 
Part VII - Pregnancy

Pregnancy is well tolerated in women with silent and small PDA or in patients with functional class 1 or 2 prior to pregnancy.

Pregnancy is contraindicated in Eisenmenger syndrome because of the high maternal (up to 50%) and fetal (up to 60%) mortality.
Grade: C	Level: V	Ref: 22

 
Part VIII - Follow Up

Patients who have been repaired should have periodic evaluation by an ACHD cardiologist because recanalization can occur or residual problems (pulmonary hypertension, left ventricular dysfunction, atrial fibrillation) may persist or develop. Patients with devices in situ should be followed periodically because the natural history of these devices is unknown. Endocarditis prophylaxis is recommended for 6 months following PDA device closure or for life if any residual defect persists. Patients with a silent PDA do not require follow up or endocarditis prophylaxis.

Grade: Consensus