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Posts Tagged ‘l +n fusion in bcav+aortic stenosis’

Bicuspid aortic valve (BCAV) is  one of the common  congenital abnormality of heart . Incidence can be 1-2% of population . It can result in premature aortic degeneration with Aortic stenosis/Aortic regurgitation or both .

The normal development and arrangement of three cusps is altered ( rather interrupted )  during fetal life.

There can be two ways BCAV can occur. One is due to the   fusion* of two leaflets to covert a  tricuspid  valve into  bicuspid  ,  and the other is    two cusps develop de novo .The former has a raphe , while the later has no raphe.

The  fusion* occurs between  either

  • Right and left (R +L)
  • Right and  non coronary cusp  (R +N )
  • or Left and Non coronary cusp (L +N)

(* The fusion is embryological , not acquired )

Most often the  fusion is due to lack of division in the valve  analgen .Hence a raphe (A conjoint remnant) is noticed .

90% of BCAV has raphe  ,only 10 % lack raphe . Aortic root is also structurally abnormal in many .(Little clinical sequale though !)

Coronary artery origin anomalies  are more common with  BCAV. We also know co-arctation of aorta has a embryological link with BCAV.

The commonest type of BCAV is

The most hemodyanmic stressed BCAV is R +N type fortunately it is rare

R + N fusion is a high risk BCAV as degeneration occur fast

The least common type is

The coronary artery origin anomalies are common

BCAV in the absence of raphe is classified separately (This constitutes 10 % of all BCAV)

The nomenclature  is

  • Antero posterior (Common type ) AP
  • Lateral (L )

What is  the pathological significance of raphe ?

Many  believe presence of raphe accelerates degeneration as leaflets have  rough surfaces . Still , BCAV with raphe has less coronary anomalies and aortic root pathology .

Presence of raphe  indicate relatively  a minor embryological defect  , as the fault is in the failure to divide after the formation of analgen , while BCAV without raphe  imply  lack of development of analgen itself . This is expressed in the coronary sinus anatomy and aortic root dimension and orientation .

So currently it is  welcome  to spot  a raphe in the patient point of view  .Echo cardiogram is notoriously  unreliable to diagnose raphe. Once degeneration process sets  in ,  it is almost impossible to recognize  the  presence or absence of raphe .

* Please note ,tricsupid aortic valve with eccentric leaflet closure  shares  a close pathological relationship with BCAV. Premature degeneration ,  (AR more common than AS here ) .This entity will be discussed separately later.

 

Image courtesey

Part of the Image (The valve) is adopted from Yale university Image Bank .

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