Peripheral Pulmonic Stenosis (PPS)

Introduction

Peripheral pulmonic stenosis (PPS), also referred to as peripheral pulmonary stenosis or pulmonary branch stenosis, is a narrowing within one or more branches of the pulmonary arteries that manifests on physical exam as a systolic ejection murmur in infants.  This murmur is often an incidental finding in neonates.  Incidence of PPS has been reported as 7 per 10,000 births (though this statistic was from a congenital defect monitoring program, suggesting the incidence of benign PPS may be higher).

Anatomy

Benign

1. In fetal circulation, about 90 percent of the blood supply traveling through the main pulmonary artery subsequently travels through the ductus arteriosus rather than the more distal pulmonary arteries. 
2. When the ductus arteriosus closes after birth, this flow is directed through the distal pulmonary arteries that are relatively small compared to the main pulmonary artery. 
3. The turbulence of blood entering these relatively narrow vessels at more acute angles than are present later in life results in a murmur.

Pathological

1. More rarely, the stenosis is an abnormal anatomic obstruction of flow in one or more of the distal pulmonary arteries.
2. Associated with congenital rubella syndrome, Alagille syndrome, Williams syndrome, and Noonan syndrome.

Physical Exam

• Generally Grade I or II systolic ejection murmur
         
  • Audible in upper left sternal border with radiation to infraclavicularregion, axilla, and back (location of maximum intensity dependent on exact location of stenosis within arteries)
• Wide, fixed splitting of S2 may be associated with other underlying pathology

A general example of a pulmonic stenosis murmur can be heard at

http://www.easyauscultation.com/pulmonary-stenosis

Pulmonic Stenosis Differential

Even after differentiated from other possible causes of asymptomatic systolic ejection murmurs (including aortic stenosis, ASD, VSD), PPS is only one of several types of pulmonic stenosis.  The other three are:

1. Pulmonary Valve Stenosis – flow obstruction at level of pulmonary valve
2. Supravalvular Stenosis – narrowing of the main pulmonary artery
3. Subvalvular Stenosis –fibromuscular narrowing under valve

Work-up

1. Recommendations regarding need for further testing, including ECG, vary.
2. If indicated, diagnosis can usually be confirmed with echocardiography.
3. If stenosis is too distal from heart to be visualized on echo and visualization is needed, other imaging modalities like MRI or CT may be appropriate.
4. If evaluation for intervention is needed, VQ Scan can help to determine resulting decreased flow to a lung.

Prognosis and Management

1. Benign type generally disappears before one year of age.
2. In PPS that is more severe (as determined by elevated right ventricular pressures and/or decreased flow to a lung on VQ scan), intervention such as balloon dilation may be indicated.
3. While PPS is generally identified in infants, pulmonary flow murmurs can be hear later in life.

Information for Patients’ Families

Short summary about heart murmurs in general from
American Family Physician

http://www.aafp.org/afp/1999/0801/p565.html
 

PPS Handout from UW Health

https://www.uwhealth.org/healthfacts/parenting/7464.pdf

Conversational explanation of PPS from Pediatric Heart Specialists group

http://pediatricheartspecialists.com/blog/peripheral-pulmonary-stenosis-pps

References

1. Biancaniello T (2005).  Innocent murmurs.  Circulation, 111, e20-e22.
2. Frank JE and Jacobe KM (2011).  Evaluation and management of heart murmurs in children.  American Family Physician, 84(7), 793-800.
3. Peng LF and Perry S. Pulmonic stenosis (PS) in neonates, infants, and children. In: Fulton DR, ed. UpToDate, Waltham, MA: UpToDate; 2015.
4. Sapin SO (1997).Recognizing normal heart murmurs: a logic-based mnemonic.  Pediatrics, 99, 616.
5. Silberbach M and Hannon D (2007).Presentation of congenital heart disease in the neonate and young infant.  Pediatrics in Review, 28(4), 123-130.