New cause for differential cyanosis : The North-South syndrome
Differential cyanosis classically occurs in PDA with reversal of shunt when raised PA pressures /PVR is able to supersede the systemic Aortic pressure and drive the blood from LPA to descending Aorta bringing down the lower limb saturation.
Of course, this can be undone by the presence of any other intra-cardiac shunts or aberrant left subclavian that arising from the desaturated descending aorta.
Other causes of reversed differential cyanosis
Where the upper body is cyanosed (desaturated) and the lower half is not. There is a conventional list of conditions.
Transposition of the great arteries (TGA) with patent ductus arteriosis (PDA) and elevated pulmonary vascular resistance
TGA with PDA and pre-ductal aortic interruption or coarctation
Supracardiac TAPVC* + PDA
Anomalous right subclavian artery connected to hypertensive ductus through RPA
(*This occurs due to streaming effect ) Highly saturated superior vena cava (SVC) blood into the right ventricle, reach MPA / through a PDA, and to the descending aorta, with streaming of more desaturated blood from the inferior vena cava (IVC) into the LA through PFO (Ref Yap S H Pediatr Cardiol. 2009 )
Now let us add one more cause for reversed differential cyanosis in the Modern Era
It is seen with ECMO in VA connection (Often reported in babies ) . The Aorta has high oxygen content entering from the femoral cannula going up into the Aortic arch., while deoxygenated blood from LV (because of failing lungs) reach antegradely to...
Source: Dr.S.Venkatesan MD - Category: Cardiology Authors: dr s venkatesan Tags: Uncategorized ecmo north south syndrome harlequin syndrome va ecmo side effects Source Type: blogs
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