|Year : 2015 | Volume
| Issue : 3 | Page : 87-89
Aortopulmonary Window: A Rare Cardiac Anomaly Presenting in Adolescent Age Group
Neeraj K Ganju, Arvind Kandoria
Department of Cardiology, Indhira Gandhi Medical College, Shimla, Himachal Pradesh, India
|Date of Web Publication||7-Sep-2015|
Dr. Neeraj K Ganju
214-B, Sector III, New Shimla - 171 009, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Aortopulmonary window (APW) is an extremely rare cardiac malformation accounting for 0.2-0.6% of all congenital heart defects. In an acyanotic patient with clinical evidence of patent ductus arteriosus with large left to right shunts and systolic rather than continuous murmur one should keep in mind the possibility of APW. If not treated early in childhood or adolescence, they tend to develop pulmonary hypertension, which can be fatal in almost all cases. Few surviving adult patients have symptoms associated with severe pulmonary hypertension, making these cases inoperable. We document an unusual case presenting in the second decade.
Keywords: Aortopulmonary window, congenital heart defects, pulmonary hypertension
|How to cite this article:|
Ganju NK, Kandoria A. Aortopulmonary Window: A Rare Cardiac Anomaly Presenting in Adolescent Age Group. Heart India 2015;3:87-9
| Introduction|| |
Aortopulmonary window is a rare congenital cardiac defect characterized by an abnormal communication between the proximal aorta and the main pulmonary artery. Large defects have symptoms of congestive cardiac failure and pulmonary hypertension due to significant left to right shunt in the early weeks of life. Irreversible pulmonary vascular obstructive disease invariably develops early in the life, followed by death in the second decade. Patients with very small defects may be asymptomatic. Few surviving adult patients have symptoms associated with severe pulmonary hypertension, making these cases inoperable.
| Case Report|| |
A 16-year-old adolescent male was referred to the cardiology department for the evaluation of a cardiac murmur under school health programme. On examination, grade II parasternal heave was present with palpable pulmonary component of second heart sound (P2). On auscultation P2 was loud. Pansystolic murmur increasing on inspiration was audible at the lower left parasternal border and another 2/4 early medium frequency diastolic murmur audible at the left midsternal border. The rest of his physical examination was unremarkable. There was no evidence of cyanosis and clubbing. Twelve lead electrocardiogram showed left ventricular (LV) hypertrophy along with features of LV volume overload. Chest X-ray showed levocardia, cardiothoracic ratio of 0.55 with a LV type of apex and pulmonary plethora. Transthoracic echocardiography was performed which revealed large aortopulmonary (AP) window with left to right shunt on color Doppler imaging in the parasternal short axis view [Figure 1]a and b. Main pulmonary artery (MPA) was dilated with moderate pulmonary regurgitation. There was moderate tricuspid regurgitation with gradient of 89 mmHg.
|Figure 1: (a) Parasternal short axis view from the transthoracic echocardiogram showing two-dimensional picture. AO, MPA, RPA, LPA, APW (b) color Doppler images of APW. AO: Aorta, MPA: Main pulmonary artery, RPA: Right pulmonary artery, LPA: Left pulmonary artery, APW: Aortopulmonary window|
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Patient was taken up for cardiac catheterization studies. Hemodynamic data suggested severe precapillary pulmonary artery hypertension. There was baseline systemic desaturation. Oxygen saturation showed significant step up at pulmonary artery level. The calculated pulmonary vascular resistance decreased significantly after inhalation of 100% oxygen for 10 min, suggesting reversible pulmonary artery hypertension. Ascending aortogram showed simultaneous opacification of pulmonary artery [Figure 2]a. LV angiogram revealed opacification of ascending aorta with filling of MPA from aorta [Figure 2]b. Computerized tomography (CT) was done, which showed contrast filled tract connecting ascending aorta and MPA with uniform opacification in the ascending aorta, the tract and MPA [Figure 3]a. Three dimensional reconstruction with volume rendering image has been shown in [Figure 3]b.
|Figure 2: (a) Ascending aortogram showing simultaneous opacification of pulmonary artery (PA). (b) Left ventriculogram demonstrating opacification of ascending aorta (a AO) with filling of main pulmonary trunk from AO|
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|Figure 3: (a) Computerized tomography scan, axial projection, demonstrating a proximal type of aortopulmonary window (APW) (arrow). Ascending aorta (AO), main pulmonary artery (MPA), right pulmonary artery (RPA), left pulmonary artery, APW. (b) Computerized tomography scan, volume rendering image showing a proximal APW (arrow). Ascending aorta (a AO), pulmonary trunk, APW|
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| Discussion|| |
The various synonyms used for this term are partial truncus arteriosus, aorticopulmonary window, aortic septal defect and AP fistula or fenestration. AP window is an uncommon cardiac congenital malformation characterized by a communication between ascending aorta and MPA. The defect usually is present midway between the semilunar valves and the pulmonary bifurcation. Embryologically, it develops as a result of deficient AP septum, which is formed at the 9-mm stage, by the two opposing truncal cushions. These truncal cushions enlarge and fuse dividing the truncus arteriosus into aorta and pulmonary artery.
The first known case of AP window was described by Professor Elliotson in 1830.  In the literature approximately 300 cases are cited in which AP window occurs as an isolated lesion.  Approximately, one-third to one-half of cases have associated cardiac defects. Arch abnormalities are the most common associated lesions, specifically interrupted aortic arch, and coarctation of the aorta. , Ventricular septal defect (VSD), tetralogy of Fallot, and transposition of the great vessels are rarely associated with AP window. 
Mori et al. classified AP window into three types. Type I defect located midway between the semilunar valves and the pulmonary bifurcation, as is present in this case. Type II defect in which the distal border of the defect is formed by the pulmonary bifurcation. Type III a large defect involving the entire AP septum.  Persistent truncus arteriosus, a large VSD and a large patent ductus arteriosus (PDA) can cause diagnostic dilemma and has to be differentiated from AP window although a rare entity. When compared with AP window, arterial desaturation is more in persistent truncus arteriosus for the same degree of congestive failure due to the common ventricular outlet resulting in complete mixing. Physical examination sometimes cannot differentiate AP window from large PDA or from persistent truncus arteriosus. Demonstration of normally related pulmonary and aortic valves will differentiate this entity from persistent truncus arteriosus on echocardiography.
Aortopulmonary window is provisionally diagnosed by echocardiography. Dropout can be seen often in the AP septum of normal patients. These normal dropout can be differentiated from aortopulmonary window (APW) by "T" artifacts at the edges of the defect as described by Balaji et al.  Confirmation is established by cardiac catheterization and angiography, which also assesses operability in the presence of pulmonary artery hypertension. However, it is an invasive procedure and is always associated with inherent risks. Noninvasive modality like magnetic resonance imaging can also be used for the diagnosis of AP window.  However, this facility is not available in every center and besides being expensive requires lot of expertise. The accurate delineation of the anatomical location, type and size of the window can be achieved with CT. This modality can also demonstrate bronchial compression by the dilated pulmonary arteries, which cannot be demonstrated by echocardiography or angiocardiography. It is a non-invasive, safe and potentially superior modality to angiography. CT being available in almost all the centers, however, artifacts due to cardiac motion should be kept in mind, while interpreting the images. Closure of the defect if performed early in life, before the development of irreversible pulmonary vascular changes, portends excellent prognosis.
| References|| |
Elliotson J. Case of malformation of the pulmonary artery and aorta. Lancet 1830;1:247.
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[Figure 1], [Figure 2], [Figure 3]