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Archive for the ‘Pulmonary arterial hypertension’ Category

IVC filter usage has increased many fold in recent years.Please note , it is not indicated in every case of recurrent DVT/or PE. There are specific indications.

Permanent IVC filters

  1. Patients at risk for DVT /PE  with  absolute contraindication to anti-coagulants.
  2. Recurrent DVT/PE in spite of adequate  anti-coagulation

Temporary /Retrievable filters*

  1. It is used during high risk periods  for DVT following major trauma or Bariatric/Spinal /Neuro surgery (PREPIC 2 study ) .*Some of the retrievable filters can be kept for months ,years or even permanently. (If the risk period extends or it has trapped a huge clot.)

 

indication for IV filter prepic study

Outcome  of IVC filter (PREPIC  -8  year follow up study )

  • Reduces risk of PE
  • Increases risk of DVT
  • No impact on long term  survival
  • Clogging of IVC remain  an important Issue

Reference

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Can we close an  ASD in a  25 year old women  severe  pulmonary hypertension ?
Volumes of literature has been written  on the subject.Dedicated cath studies  have been done with multiple parameters .
Still , there is a lingering doubt !
Here is  a  3 minute  practical solution  based on 5 easily available parameters. (* Also referred to as  unscientific  in medical parlance !)
1.  O2 saturation
2. Pulmonary artery diastolic and pulse pressure
3. RV function,
4 .Systemic pressure
5. Functional class
  • If O2 saturation is > 90 % consistently  there is likely to be significant  left to right shunt  .Closure is to strongly considered
  • If 02  saturation is near 95 % there is absolutely no contraindication at any level of PVR.
  • Systolic pulmonary artery pressure derived by TR jet is least useful index.Pulmonary artery diastolic pressure reflects true vascular  reactivity of the pulmonary  circulation.A wide swinging pulmonary arterial pulse indicates dynamism in circulation and hence operablity.
  • If pulmonary artery  pulse pressure is  wide (>50)  , or PA diastolic BP is < 30 one can safely presume irreversible damage to pulmonary vasculature has not occurred and these patients would  benefit  from surgical closure .
  • RV  function should be assessed carefully in every patient.This is as important as PVR .Significant RV dysfunction is an absolute contraindication.
  • Never close the shunt in patients who is in class 4  symptoms.
  • Never close a shunt if the systemic blood pressure is low( 90mmhg)
  • Some believe  PDA may be closed at any given PVR , while  worst outcomes occur with ASD as supra-systemic pulmonary pressure is possible.
Always monitor these patients meticulously especially  in the initial days following surgery  for deterioration .Most patients will do well if they cross the first 30 days. The RV  learns to adopts with  new  pulmonary hemodynamics !

 

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When I asked this seemingly simple  question to my cardiology fellows , I found they struggled  to come out with a proper  answer .I hope this will  make the  issue simpler .

Why the onset of PAH in VSD is early and late in ASD ?

Though number of factors are involved in the genesis of PAH , the single important reason  is  behavior of pulmonary circulation  especially the pulmonary arteriolar muscle .

Normal pulmonary vasculature losses it’s muscle rapidly after  birth and the pulmonary vascular resistance (PVR) falls to the adult level by 6 months .(Bulk of the fall occur in first 60 days) This is the same time the RV dominance is lost and RVH regresses . This also coincides with peaking of  left to right  shunting peaks and may result in cardiac failure .

Though  both ASD and VSD shunts are  highly dependent on PVR ,   VSD  shunting has more muscle power namely the LV contractility  , hence  VSD shunt is established  much earlier   than ASD . This can be ascertained in bedside as  VSD murmurs are heard even within 30 days while ASD is silent for many moths or even years . (Does not apply for Primum defects)

ASD  shunt rarely  meddles   lung  maturation process .(Maturation here means loss of  pulmonary arterioloar smooth  muscle -also  called as Involution  )  This vital  initial period lasts up to 6 months of life .VSD  interferes with this  involution of pulmonary arteriolar smooth muscle .( Please note near complete  involution still can occur in small VSDs with very little shunting )

In large VSD the PVR  will never ,  ever fall to normal levels  and   making it easier for  progressive vascular changes  that occur in  untreated large VSDs that  lead to Eisenmenger syndrome

*Please note  ASD can also reach that stage but it takes many years as the pulmonary vascular resistance has to raise from  very low levels which was made possible by complete involution of pulmonary vasculature .

It is obvious   AP window , PDA  express more  powerful left to right shunts which are associated with very high PVRs .

Final message

A simplified version of answer

Version 1

In VSD  the onset  of left to right  shunt occurs early even within 3 months of life  since VSD shunt is augmented by LV contraction . This is the crucial time of lung  vascular maturation   which gets interfered with  .ASD shunt is  established only after the pulmonary vasculature  involutes .This explains early onset of PAH in VSD  and late in ASD .

Version 2

ASD shunting is primarily depend on RV compliance which is high in early infancy so it takes time to establish the shunt .while VSD shunting does not  depend upon this RV regression.

* Please note  regression of  RV  dominance and compliance is directly dependent on maturation of lung.

** Note these  explanations are not absolute .Some of the complex forms of ASD and intrinsic vascular injury of pulmonary circulation (Various  fetal distress )  can progress into accelerated pulmonary arterial hypertension

Reference

  1. Excellent discusions are available in old edition of Moss and Adams
  2. Rabinovitch has done pioneering work on this topic .
  3. Robert Roberts text book of Adult congenital heart disease also explains it succinctly

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