Abnormal Outflow Tracts



Abnormal Outflow Tracts


Michael D. Puchalski, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Hypoplastic Left Heart Syndrome (HLHS)


  • Tricuspid Atresia (TA)


  • Tetralogy of Fallot (TOF)


  • Pulmonary Valve Stenosis, Atresia


Less Common



  • Transposition of Great Arteries (TGA)


  • Double Outlet Right Ventricle (DORV)


  • Truncus Arteriosus


Rare but Important



  • Interrupted Aortic Arch (IAA)


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Are there one or two ventricles?



    • If a ventricle is hypoplastic, the corresponding great vessel is typically small or atretic


  • Is a ventricular septal defect (VSD) present?



    • Does the aorta override the interventricular septum?


  • Do the great vessels exit the heart side by side?



    • Normal relationship is for the great vessels to cross as they exit the heart


  • Are the aorta and pulmonary artery (PA) similar in size (i.e., normal), or is there a discrepancy?


  • Are ductal and aortic arches present?



    • Ductal arch is often larger than aortic arch


    • Normal flow in the ductus arteriosus is right to left



      • Reversed in pulmonary atresia as PA fills retrograde from aorta


    • Retrograde flow in the aortic arch suggests left-sided obstruction



      • Aortic arch fills retrograde from PA via ductus


Helpful Clues for Common Diagnoses



  • Hypoplastic Left Heart Syndrome (HLHS)



    • Abnormal four chamber view with small, non apex-forming left ventricle (LV)



      • May see brightly echogenic LV endocardium with endocardial fibroelastosis


      • Ventricular function is poor


      • Interatrial septum bowed left to right


    • Aortic valve often is atretic or very small


    • Ascending aorta and transverse arch are very small


    • Right ventricle (RV) is large and wraps around the LV apex



      • Function is typically very good


  • Tricuspid Atresia (TA)



    • Abnormal four chamber view with small, non-apex-forming right ventricle



      • Tricuspid valve appears “plate-like” with no movement


      • VSD usually present → blood flow to great artery arising from RV


    • Size of great artery arising from RV (PA or aorta) depends on size of VSD



      • Larger VSD → bigger artery


    • Left ventricle is normal to large in size with good function


  • Tetralogy of Fallot (TOF)



    • Dilated aortic root overriding a VSD


    • Pulmonary stenosis almost always present



      • Commonly due to anterior deviation of the infundibular septum


    • Both ventricles normal in size



      • RV may be hypertrophied if significant pulmonary stenosis


  • Pulmonary Valve Stenosis, Atresia



    • Pulmonary valve stenosis typically → normal sized RV and small pulmonary valve



      • Turbulent, high velocity flow is noted across the valve


      • Often accompanied by tricuspid regurgitation


    • Pulmonary atresia with intact ventricular septum → hypoplastic right ventricle



      • Reverse flow in the ductus arteriosus


      • Ductus more vertically oriented than usual


      • Abnormal coronary flow suggests coronary sinusoids


      • Right ventricular pressure is greater than systemic


    • Pulmonary atresia with VSD



      • VSD is large


      • Aorta may override septum


      • Pulmonary arteries may be absent or very small


      • Collaterals off the descending aorta may be the only blood supply to the lungs



Helpful Clues for Less Common Diagnoses



  • Transposition of Great Arteries (TGA)



    • Outflow tracts parallel as they exit heart


    • Aorta arises anteriorly from RV


    • Pulmonary artery arises posteriorly from LV


    • VSD common


    • Both ventricles are of normal size with good function


  • Double Outlet Right Ventricle (DORV)



    • Prominent, dilated aortic root overriding a VSD



      • > 50% of aortic root arises from RV


    • Outflow tracts parallel as they exit the heart



      • Usually normally related with aorta posterior to PA


    • Ventricles are normal in size unless associated atrioventricular (AV) valve atresia


  • Truncus Arteriosus



    • Single great artery (truncus) exits the heart



      • Branches into an aorta and pulmonary trunk


    • VSD almost always present


    • Truncal valve often abnormal with stenosis or insufficiency



      • Count valve leaflets of great artery, if > 3 image truncal valve


    • Both ventricles are normal in size with good function


Helpful Clues for Rare Diagnoses



  • Interrupted Aortic Arch (IAA)



    • Arch gives rise to one or more vessels which extend straight into neck



      • Normal “candy cane” arch view is not attainable


      • Blood supply is only to head → aorta is small in size


      • Ductus arteriosus supplies all blood to lower body


    • VSD usually present with posterior deviation of septum


Other Essential Information

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Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Abnormal Outflow Tracts

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