1. Fetal medicine unit, Kasr Alainy hospital, Cairo University, Egypt;
2. Radiology department, Kasr Alainy hospital, Cairo University, Egypt.

Case report 

A 23-year old woman (G2P1) with unremarkable family history was referred to our institution at 25 weeks of gestational age due to abnormal fetal heart. Our ultrasound examination revealed the following findings:
-  Small sized, severely hypo plastic tricuspid valve annulus, yet, with patent tricuspid valve leaflets showing antegrade flow across with trivial early systolic tricuspid regurgitation.
-  Vigorous right to left flow shunt across foramen ovale between the small right atrium and the large left atrium. 
-  Totally disconnected main pulmonary artery from the infundibular portion of the RV with non visualized pulmonary valve leaflets.  
-  Ductal dependent pulmonary circulation. The small main pulmonary artery and its confluent central branches are seen with complete retrograde filling from the tortuous arterial duct. 
-  Situs solitus with concordant atrio ventricular and ventriculo arterial connections.
- The right coronary artery is seen dilated (ectatic) at its proximal and mid segments with a fistulous communication between the RV branch of the RCA and the right ventricular free wall. A bidirectional flow pattern in the RCA is seen with significant systolic retrograde flow inside.

Our final diagnosis was pulmonary atresia with intact ventricular septum associated with ventriculo-coronary communication (RCA to RV fistula).

A well defined vascular structure was seen just cranial to the ectatic proximal RCA with a suspicious fistulous communication between the ascending aorta and left atrium. This finding was strikingly found in glassbody rendering of an offline color STIC volume. Reviewing the 2D and color Doppler exam, we found that this vascular structure is the left atrial appendage having a chicken wing appearance. 

For unknown apparent reason, the follow up study at 28 weeks gestation revealed intra uterine fetal death. Parents refused pathological examination due to religious aspects.

Images 1, 2; videos 1, 2: Show the hypoplastic right ventricle with complete obliteration of apical trabecular and outflow parts, dominant left ventricle and intact ventricular septum.

Images 3-6; videos 3-5: 2D and color Doppler images and videos showing the small inlet cavity of the RV with trivial TR, retrograde flow through tortuous arterial duct filling into both confluent central pulmonary arteries. 

Images 7 and 8; videos 6 and 7: Show the dilated proximal RCA with bidirectional flow pattern and the RCA to RV fistula of the surface of the RV.

Images 9 and 10; videos 8, 9 and 10: Show the chicken wing appearance of the left atrial appendage.

Images 11 and 12; videos 11, 12 and 13: Glass body color STIC volume rendering showing the hypoplastic RV with residual small inlet cavity, right to left flow shunt across foramen ovale during both systole and diastole, retrograde flow in the tortuous arterial duct filling into both confluent central pulmonary arteries.

Images 13-18; videos 14-18: Glass body color STIC volume rendering  showing the ectatic RCA and the RV to RCA fistula.

Image 19: Glass body color STIC volume rendered image showing the parallel cranio caudal arrangement of the chicken wing appearing left atrial appendage and the ectatic proximal RCA.

Discussion:

This case represents the most severe morphological variant of pulmonary atresia with intact septum in which marked hypoplasia of the right ventricle is present leaving only a small inlet cavity together with severely hypo plastic tricuspid annulus. The hypertensive right ventricle (marked elevation of both end systolic and end diastolic RV pressures due to RV outflow tract atresia and intact ventricular septum) forces the blood mainly through the intra myocardial sinusoids with  consequent fistulous communication with the epicardial RCA branches and by a lesser extent through the small tricuspid valve annulus as a trivial regurgitation. The main outflow of the hypertensive RV will be the fistulous connection with the RCA for which a systolic retrograde flow in the ectatic proximal RCA is noted^1,2. This retrograde filling of the coronary circulation from the hypertensive right ventricle carries the risk of right ventricle dependent coronary circulation if there is associated atresia or stenoses in the proximal major coronary arteries that could be visualized by an angiographic study in post natal life³.

This morphological variant of the pulmonary atresia with intact septum and ventriculo-coronary communication represents a critical condition that prompt the early postnatal prostaglandin infusion to maintain ductal patency. The second immediate intervention should be either ductal stenting (could not be done in this case owing to marked tortuousity of the arterial duct) or modified Blalock Tausig Shunt (of choice in this case) to enhance the arterial growth of the confluent branch pulmonary arteries prior to total palliative repair by a single ventricle procedures.

Surgical RV decompression (RV to pulmonary artery valved conduit) in this case will be of no value because the residual small inlet cavity will not be sufficient to act as a single pulmonary ventricle as well as the associated risk if there is right ventricle dependent coronary circulation (RVDCC) as there will be catastrophic myocardial infarction and even myocardial rupture and neonatal death if surgical RV decompression is done in the presence of RVDCC (Steal phenomenon)⁴.

References:

1- Chaoui R, Tennstedt C, Goldner B, Bollman R. Prenatal diagnosis of ventriculo-coronary communications in a second trimester fetus using transvaginal and transabdominal color Doppler sonography. Ultrasound Obstet Gynecol 1997; 9:194–197.

2- F. TADDEI, M. SIGNORELLI, C. GROLI, S. SCALCHI and U. A. BIANCHI. Prenatal diagnosis of ventriculo-coronary arterial communication associated with pulmonary atresia. Ultrasound Obstet Gynecol 2003; 21: 413–415.

3-Powell AJ, Mayer JE, Lang P, Lock JE. Outcome in infants with pulmonary atresia, intact ventricular septum, and right ventricle-dependent coronary circulation. Am J Cardiol 2000;86:1272–4.

4- Kristine J. Guleserian, Laurie B. Armsby, Ravi R. Thiagarajan, Pedro J. del Nido and John E. Mayer. Natural History of Pulmonary Atresia With Intact Ventricular Septum and Right-Ventricle–Dependent Coronary Circulation Managed by the Single-Ventricle Approach. Jr Ann Thorac Surg 2006;81:2250-2258.