Flow reversal in arch of aorta Dr Neeraj Aggarwal Paediatric Cardiologist Department of Paediatric Cardiac Sciences Sir Ganga Ram Hospital, New Delhi

Common causes Communication between the ascending aorta, the proximal aortic arch or its branches, and a lower pressure chamber or channel (such as pulmonary vessels, ventricles, or systemic veins), that results in stealing of blood from the distal aortic arch and descending aorta Examples – Aorto - pulmonary window, severe AR, Arteriovenous (A-V) malformation of the head and neck vessels, coronary artery fistula and systemic to pulmonary fistula 2. Severe LVOT obstruction such as critical AS or HLHS

Case 1- Aorto Pulmonary Window 4 month old ,presented with ARDS and Pneumothorax-kept on high frequency ventilation Past history of recurrent chest infections and failure to thrive On examination- bounding pulses, Ejection systolic murmur ,heart sound not clear. CXR – cardiomegaly (CT ratio -60%) Echo- very poor images in subcostal and thoracic windows and no diagnosis could me made. Suprasternal window –No PDA, reversal In arch present

CT angiogram -AP window

Case 2 (2 patients) - Vein of Galen malformation Neonate - 2 days old Admitted with Congestive heart failure Echo –PFO and PDA right to left , PAH , reversal in arch Further interrogation –prominent innominate vessels, SVC flow increased Cranial bruit present Suspected cranial Arterio-venous malformation-confirmed by cranial USG and MRI

Echo –SVC flow

PFO and PDA right to left

Case 3-Critical AS Neonate 1 day old, presented with shock Echo showed LVEF 10 % with restricted aortic valve opening (PG 16 mmhg),PDA shunting BD Reversal in aortic arch

Case 3-Critical AS Underwent Balloon aortic dilatation Post procedure echo – no reversal in arch Ejection fraction takes time to recover but reversal subsided immediately May suggest improved Left ventricular cardiac output

Critical AS

Before and after BAV

Case 4-Truncus arteriosus 5 year old male, Failure to thrive, recurrent chest infections, loud P2 CXR-Cardiomegaly, high Qp, saturations 94 % Echo –Truncus arteriosus type 1,no Truncal valve regurgitation, reversal in arch (indicating low PVR ) Oximetry studies –not useful

CXR and Echo

Case - Truncus arteriosus Underwent complete repair Patient extubated on table in OT Pre discharge echo –mild TR ,PG 35 mmhg Discharged on 7th post operative day

Case 5- Anomalous origin of RPA from aorta 6 yr old female child ,with recurrent chest infections and not growing well Diagnosed as RPA origin from aorta ,MPA continued as LPA with large PDA, no intracardiac shunts Clinical data shows operability (saturation -95 % in both upper limbs and 93 in lower limbs , CXR- Cardiomegaly with high Qp )

CXR PA view

Echo

Anomalous origin of RPA from aorta Reversal in arch of aorta –indicates low resistance in RPA Lack of differential saturation between upper and lower limbs indicates LPA having hyperkinetic PAH In OT- temporary occlusion of PDA led to fall in LPA pressure {from 95/48(68) to 57/21(37) } Patient underwent surgical repair with unifocalization of RPA to MPA. Patient extubated in OT . Pre discharge echo showed mild TR ,PG of 30 mmhg

Case 6 –Obstructed TAPVC 2 weeks old neonate, diagnosed with obstructed supra cardiac TAPVC, restrictive PFO,PDA shunting right to left. Severe PAH with reversal in arch Cranial auscultation –no bruit, USG brain –no cranial AV malformation

Case 6 –obstructed TAPVC TAPVC repaired Post op echo –no reversal in arch Hypothesis- PAH with low cardiac index can lead to reversal in arch

Case -7 Neonatal PAH Full term neonate ,meconium aspiration ,kept on ventilator Echo –PPHN, PFO BD shunt ,PDA right to left shunt ,systolic function normal, reversal in arch Patient needed pulmonary vasodilators ,high frequency ventilation and NO ventilation

Neonatal PAH Cranial auscultation and USG skull normal After 14 days patient improved ,could be weaned from High frequency ventilator and NO and Echo showed loss of reversal in arch along with fall in PA pressures Patient was finally extubated after 1 month.

Case 7-B-- PPHN Almost same presentation Family refused for ECMO Patient succumbed to disease on day 14 of life

Case 9-ALCAPA 40 yr old female with DOE class 2,echo showed moderate MR, No AR and LVEF 55 % ,on follow up since last few yrs at many institutions

Conclusion Flow Reversal in arch of aorta can be correlated for supportive evidence in various diagnostic and operability dilemmas as in Truncus arteriosus, Hemitruncus and AP window. Cerebral AVM can be suspected on the basis of echocardiogram Low cardiac output associated with PPHN may lead to reversal in arch in neonates and may guide for early aggressive therapy loss of “reversal in arch” after BAV in critical AS after may be taken as additional marker for improvement in LV output( before LV function starts improving) Non cardiac lesions like severe septicaemia with low SVR can also lead to reversal in arch and should be clinically judged.

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