Posts Tagged ‘acyanotic forms of tof’

Benjamin Gasul  is a well-known name  in  cardiology community especially  among the old generation . He and  his team from  Cook  county children’s hospital  Illinois,  Chicago,  created a stir among pediatric cardiologists  in late 1950s and 60s . His concept  was rather controversial .He suggested   Tetrology of Fallot can be an  acquired  defect as a sequel to  large   peri-membranous VSD.

He and his team published a series of papers one in 1957 and other in 1963 (JAMA and circulation ) .Later in 1970s  Kieth  and  Tyrrell  from children’s hospital Toronto tried to confirm this. Though they were not fully agreeing with  Gasul  they could not dispute the concept either !

Clinical importance of Gasul VSD

This entity was suspected based on a  curious observation  in children with large VSDs ,  who initially struggle with the defect and   show signs of  failure   . After a critical time frame  (If  they survive )  they  begin to stabilise and some of them do extremely well  in functionality too !

For this to happen , we presume the  quantum of  shunt  must  reduce by any means. Ironically ,  we also know , even patients who are destined to develop dangerous Eisenmenger reaction also live a blissful life for a decade or so  before it strikes  and  take  their life . This is one aspect of the natural history   . . .

While  some ther  children did well without developing  pulmonary hypertension  .This bothered  Gasul .When he analysed those patients (Mind you  there was no echocardiography  those days !)   he found something curious  was happening in the RVOT area. (It was almost like TOF !) This he documented in few patients  who showed progressive infundibular narrowing   acting as a check dam (Artificial banding ? ) and resulted in improvement of  VSD hemo-dynamics  .In extreme situations there was  a significant  right to left shunt as well. It was so tempting  to label it as acquired TOF !

Who are likely  to develop  Gasul  like reaction ? (Reference : Kieth 1978  Heart disease in Infancy and child hood.)

  • Persons with  oblique RVOT angle normal <40 ( 40-60 degrees)
  • Aortic override ride > 30%
  • Patient with anomalous muscle bundle
  • Children with right aortic arch

Why the concept of  Gasul was disputed ?

Gasul  concept primarily relied on the fact that  there  would be  some resistance at RVOT  for all those dramatic improvement in failure  as  the children grows .  This he consistently documented in many children who had significant regression of cardiomegaly .

There can be other mechanisms for  the signs of stabilisation in large VSDs.

Relative  reduction  of VSD size as child grows  could be an  important factor .  The falling pulmonary vascular  resistance  allows to  accommodate   the shunted  blood  without  any major issue as RV  after- load regress .

Is concept of  Gasul  alive   in the year 2012 ?

Since  it represent the natural history  of the defect  , most VSDs are closed surgically ,  one may not get an occasion to see a Gasul VSD today . More intriguing is the fact  we will ever get an oppurtunity to  confirm the concept .

Special  situations in  VSD / PS . Can RVOT obstruction  exist with raised pulmonary  arterial pressure ?

This  is a challenge to the traditional teaching . Logically pulmonary obstruction   and  high  pulmonary pressure  does not go hand in hand.Do not get fooled by logic .(We know aorta can record  even  200mmhg  in critical aortic stenosis ).

The respect and command  we give to clinical medicine   even  today is because ,  it can defy logic in  any random patient .

If a  patient with Eisenmenger  develop  Gasul reaction what will happen ? PAH will persist  as do the RVOT obstruction .They are the  blessed  ones and  belong to the category of   Eisenmenger surviving into 4th  5th decades . (Batisda of  Brazil extrapolated this and suggested huge benefits with  PA banding in adult Eisenmenger !)

Summary and verdict

TOF is a cono-truncal anomaly due to defective genes. The Mal-aligned  conal  septum is responsible for RVOT obstruction . Hence  this defect can not be termed as  acquired  , by  any  sort of imagination .

Still , a subset of patient with large VSD  can mal-align their conal  septum for hemo-dynamic  reasons .This  is  especially likely to occur  if the flow is heavy the infundibulum  slides horizontally to generate the obstructive  gradient .  Hence  Gasul was  indeed right when he pointed  to us some of the   grown children with VSD  mimic  TOF .

However,  the controversy remains  whether  the equation  “Adult VSD + IPS” = Adult  TOF  is  true or  false !

Incidentally , the classic book on congenital heart disease by J.K Perlof has a chapter on VSD with PS  and not  on TOF  !  Does it light  a spark ?  Is it worth pondering this question ? Probably not ,  instead we may use our resources to  correct these anomaly  .


Gasul’s  original article published in 1957 (Only abstract )



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