COARCTATION OF AORTA DIAGNOSED BY RENAL DOPPLER

COARCTATION OF AORTA DIAGNOSED BY RENAL DOPPLER IN A HYPERTENSIVE CHILD

Coarctation of the aorta is an abnormal  narrowing of the aorta that occurs as a result of persistent muscular tissue in the region of the ligamentum arteriosus. Coarctation most commonly seen  opposite the ductus arteriosus, caudal to origin of the left subclavian artery and is called juxta-ductal coarctation. Coarctation is a cause of secondary hypertension, resulting in differential pressures in the upper and lower extremities.   

CASE DETAILS

A13 yr young boy with hypertension [ BP upper limb 150/98] , subjected to abdominal ultrasound with special study for renal Doppler . Abdominal organs were normal at USG. On renal Doppler examination both sided main renal arteries were poorly seen & could not be clearly scanned. However in this case study  a low velocity low resistance  tardus -parvus waveform is seen in both sided intrarenal  renal arteries [fig 1 & 2 ].  The parvus tardus waveform of the renal artery is characterized by a slow rise of peak velocity distal to the stenosis, prolonged acceleration time and reduction of ipsilateral resistive index. This suggested that a stenosis proximal to the point being studied may be present. The supra-renal aorta showed a monophasic and dampened flow due to low flow velocities [ fig 3 ], further suggesting that a more proximal narrowing is likely , & that could be coarctation of aorta  . So , a possible diagnosis of coarctation of aorta was proposed .  Further examination by CT scan confirmed  the presence of juxta-ductal coarctation [ fig 4 & 5 ].

Fig 1-  Right intrarenal doppler shows tardus-parvus flow pattern . Note the decreased arterial peak systolic velocity & prolonged systolic peak acceleration time , which indicates proximal stenosis

Fig 2- Left intrarenal arterial doppler with similar tradus-parvus flow pattern

Fig 3 - Abdominal aortic doppler scan shows dampened monophasic blood flow spectrum due to low velocities , suggesting more proximal stenosis

Fig 4-  Sagittal CECT chest shows aortic stenosis [ c ] in juxta ductal isthmus of aorta [ AO ] caudal to left subclavian artery

Fig 5 - Coronal CECT chest shows juxta ductal aortic stenosis 

Take home point from this case: Look for a more proximal stenosis when abnormal bilateral renal artery waveforms [ tardus-parvus ] and abnormal aortic waveform [ dampened ] are noted. 

PS – The case study in intended for medical professionals & imaging specialists for academic purpose