Anomalous pulmonary artery membrane: A rare membrane obstructing right pulmonary artery orifice

Saji Philip; K Ganapathy Subramaniam; Sunil Agrawal; Cherian Kotturathu Mammen

doi:10.4103/jiae.jiae_5_18

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Year : 2018 | Volume : 2 | Issue : 2 | Page : 127-129

Anomalous pulmonary artery membrane: A rare membrane obstructing right pulmonary artery orifice

Saji Philip¹, K Ganapathy Subramaniam², Sunil Agrawal¹, Cherian Kotturathu Mammen³
¹ Division of Pediatric Cardiology, St. Gregorios Cardio-Vascular Centre, Pathanamthitta, Kerala, India
² Department of Cardio Thoracic-Surgery, Fortis Malar Hospital, Chennai, Tamil Nadu, India
³ Department of Cardio Thoracic-Surgery, Frontier Lifeline Hospital, Chennai, Tamil Nadu, India

Date of Web Publication

6-Sep-2018

Correspondence Address:
Dr. Saji Philip
St. Gregorios Cardio-Vascular Centre, Dr. K M. Cherian Heart Foundation, Parumala, Pathanamthitta - 689 626, Kerala
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiae.jiae_5_18

Abstract

Different types of anomalous bands, membrane, tendon, and venous valves have been described in the heart, but not within the great arteries of the heart. Here, we present a 3-year-old female child diagnosed to have a crescentic membrane originating from the superior8211;posterior wall of the pulmonary artery (PA) at bifurcation and obstructing the orifice of right PA producing significant gradient across the artery. Histopathology of this membrane showed fibrous tissue, and possibly this could be a membranous fold forming at the bifurcation of PA during the development of branch pulmonary arteries from the sixth aortic arch.

Keywords: Anomalous membrane, pulmonary artery, right pulmonary artery obstruction

How to cite this article:
Philip S, Subramaniam K G, Agrawal S, Mammen CK. Anomalous pulmonary artery membrane: A rare membrane obstructing right pulmonary artery orifice. J Indian Acad Echocardiogr Cardiovasc Imaging 2018;2:127-9

How to cite this URL:
Philip S, Subramaniam K G, Agrawal S, Mammen CK. Anomalous pulmonary artery membrane: A rare membrane obstructing right pulmonary artery orifice. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2018 [cited 2019 May 23];2:127-9. Available from: http://www.jiaecho.org/text.asp?2018/2/2/127/240638

Introduction

Anomalous or aberrant bands in chambers of heart such as intraatrial anomalous band crossing the right atrial cavity, left atrial anomalous band, false tendons in left ventricle, aberrant bands in right ventricle, chiari's network, long Eustachian valve ^{More Details}, intraatrial band in the right atrium, etc., were reported, and some are clinically significant.^{[1],[2],[3],[4],[5],[6],[7]} However, there are no data or publication on any anomalous membrane originating from the pulmonary artery (PA) and obstructing the branch of PA. Here, we report a 3-year-old female child who presented with a heart murmur and diagnosed to have a moderate-size secundum atrial septal defect (ASD) with a rare anomalous membrane originating at the bifurcation of PA, obstructing the right pulmonary artery (RPA) orifice. She underwent surgical resection of membrane and ASD closure.

Clinical Presentation

A 3-year-old female child weighing 11 kg, failure to thrive presented with a history of heart murmur. Cardiovascular examination revealed grade 2/6 ejection systolic murmur at the left sternal border, conducted to the right mid chest. PA stenosis was clinically impressed. X-ray and electrocardiography were within normal limit other than the mild increase of bronchovascular markings at the left lung field. Parasternal short-axis view showed a long membrane measuring 9 mm, originating at the PA confluence, extending to RPA artery orifice (5.3 mm), and obstructing at the origin of right pulmonary flow with a gradient of 66 mmHg PG [Figure 1]a and [Figure 1]c. Proximal right and left PA were measured as 7.7 mm and 8.8 mm, respectively. Subxiphoid bicaval view of transthoracic echocardiogram showed high type moderate-size secundum ASD measured as 98211;10 mm in width with the left to right shunt [Figure 1]b. Although it was a borderline divisible septal defect, surgical team had advised for surgical intervention in view of ASD in the association of RPA stenosis caused by membrane obstructing at the orifice of RPA.

Figure 1: (a-d): Two-dimensional echocardiogram, (a) Parasternal short-axis view showed an elongated thick membrane (<) originating at the bifurcation of pulmonary artery and obstructing the orifice of the right branch of pulmonary artery. (b) Subcostal biatrial view showed a high type moderate-size secundum atrial septal defect measuring 11.5mm with color flow across the defect. (c) Cartoon depicts the membrane at the bifurcation obstructing right pulmonary artery orifice. (d) Parasternal short-axis view of routine echocardiogram in normal cases rarely showed short and thin membrane originating at the bifurcation of pulmonary artery (<) without obstruction. PA: Pulmonary artery, RPA: Right pulmonary artery, LPA: Left pulmonary artery

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Operative finding was described as a thin semi-lunar or crescentic irregular membrane originating near the superior and posterior wall of the PA bifurcation obstructing the orifice of RPA [Figure 2]a. Mild narrowing of proximal third of RPA was seen. Resection of obstructing membrane and plasty had been done at the proximal portion of RPA along with the ASD closure. The membrane had been sent for the histopathology study which showed fibrous tissue [Figure 2]b and [Figure 2]c and special stain for demonstrating elastin was negative [Figure 2]d. Clinical implications were further discussed.

Figure 2: (a-d), (a) Operative picture of the thin crescent irregular membrane (<) at the orifice of the right branch of pulmonary artery. (b and c) Hematoxylin and Eosin stain of the pulmonary artery membrane; ×10 and × 100 view showed fibrous tissue. (d) Verhoeff stain; ×100 view showed no elastin

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Discussion

Different types of bands, membrane, and venous valvular structures such as chiari's network and long eustachian valve were reported in both atrial and ventricular cavities, but not within the great arteries of the heart ^{[1],[2],[3],[4],[5],[6],[7]} These are benign anomalous structures or normal anatomical variants with or without clinical implications. This filamentous structure can be visualized rarely by routine two-dimensional (2D) echocardiogram at the confluence or at the region of angle of bifurcation of PA at various lengths, which is benign in nature [Figure 1]d. However rarely it can be longer and may obstruct the orifice of RPA. Gradient across the RPA was significant enough to proceed for the intervention. This can produce unilateral PA hypertension and right ventricular dysfunction. Animal model also suggested that an increased PA resistance contributes to abnormal right ventricular afterload which is determined by PA impedance.^[8] Hence, relieving the stenotic gradient at the peripheral PA was necessary to prevent other complications. Surgical excision was done, and histopathology showed fibrous tissue. Verhoeff special stain for elastin was negative, and there is no evidence of any ductal tissue in the membrane proved by histopathology.

Embryologically, PA develops from the sixth aortic arch. The proximal part of the sixth right arch persists as the proximal part of the RPA while the distal section degenerates; the sixth left arch gives off the left PA and forms the ductus arteriosus continuous with descending aorta, and this duct remains open entire fetal life. Wilhem His, Jr, showed that in the early embryo the right and left arches each gives a branch to the lungs, but later both pulmonary arteries take origin from the left arch.^{[9],[10],[11]} Hence, possibly, this could be a membranous fold forming at the bifurcation of PA during the development of branch pulmonary arteries from the sixth aortic arch, and further studies may be needed on incidence and embryological origin of this membrane.

Conclusion

Different types of anomalous bands, membrane, tendon, and venous valves were described in the chambers of heart, but not within the pulmonary artery bifurcation level. This membrane can be seen normally at various lengths without any obstruction. But when it becomes longer, may obstruct the orifice of peripheral pulmonary artery which can be well demonstrated By two-dimensional Doppler echo cardiogram and may need intervention.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgments

Dr. Asha Punnoose MD, Department of Pathology, International Cancer Care Center and Multispecialty Hospital, Parumala, Kerala, for histopathology and special staining.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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