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Posts Tagged ‘ASD device closure’

 

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The following  factors are critical determinants of the success of ASD device closure

  1. Location of the defect ( Only ostium secundum )
  2. Size of the defect (<35mm .Never forget  simple truth , larger the defect shorter would be the  rim )
  3. Shape  of the defect (Please note ,none are strictly circular but most devices are ! )
  4. Eccentricity of the defect (RA aspect of ASD need not match LA aspect)
  5. Length of the rim ( 5mm said to be adequate)
  6. Thickness of the rim ( Least respected parameter .Thin filament like rims are notorious  in sagging the device into RA)
  7. Pre and Per- operative TEE (As Vital as the procedure)
  8. Technical expertise . (This includes extreme patience  of the primary operator .Most sub optimal results and complications are related to this.
  9. Good team ( Not every  interventional  cardiologist should  attempt this !)
  10. Courage to abandon the procedure
  11. Device brand (Probably less important )

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ASD device closure is rapidly gaining  popularity . Amplatzer device occluder  has become a de-facto standard. Contraindications are declining . More and more young cardiologists want to  indulge in this  play . Fortunately  cost of  device is  acts as a major  deterrent  .

The pre procedural evaluation seems to be many fold important than the procedure itself.

  1. Evaluation of    Rims
  2. Thickness of  IAS
  3. Estimation of size of the defect
  4. Shape of the defect*
  5. RA /LA size  orifice  discrepancy*
  6. Proximity to Aorta, AV node
  7. Ruling out fenestrated  (daughter defects)

* You ask any cardiac  surgeon ,  How variable   the shape and size of ASD  can be ? To complicate the issue the LA side may show an entirely different shape and diameter compared to RA aspect. The orifice by itself may  travel obliquely.

Currently  the thickness of IAS* is not taken into account in device selection . It may be unwise to do so , because the thickness of the rim  and its interaction with device determines which direction the device will drag  (Homing in )  in the long run .

The potential dead space between the device and the septum can be a  late focus for thrombosis.  CVAs have been reported following ASD device closure.

Classification with reference to size

ASDs can be small (3 to <6 mm), medium (6 to <12 mm), or large (>12 mm),

What is the shape of Ostium secundum ASD ?

  • Round (perfect round very rare)
  • Oval
  • Irregularity oval
  • Irregularly round
  • Combinations

How is the orifice orientation with reference to plane of IAS ?

  • Horizontal
  • Oblique
  • Combination of the two

Which is the best method to measure the ASD size ?

  • Trans-thoracic Echo
  • 2DTrans-Esophageal Echo
  • Balloon estimated ASD size in fluoroscopy
  •  Real Time 3D TEE
  • Intra-cardiac Echocardiogram

Currently there is some degree of confusion about utility value of balloon sizing . Opinion differs. A meticulously done TEE  may be the  winner

How do you tackle an elongated and Oval ASD ?

A large ASD with an adjacent daughter ASD . It is very difficult identify this daughter defect by conventional imaging . Intra cardiac Echo may help . Failure to recognize fenestrated defects especially in the edge can lead to poor device approximation

Con-founders in ASD size measurement.

Stretched ASD diameter. (How  much stretch ? )

Systolic vs diastolic ASD size

Practical tips for ASD sizing

Add 2mm to balloon/TEE  estimated waist.

TEE  may be more accurate than the balloon .

Balloon has a inherent issue of over stretching the ASD  and false high diameter.

Waists are often circular in the device   We do not  have oval Amplatzer device.

Accurate sizing is very difficult to achieve ,   so which side is better to err  ?    lesser or over  size  ?

Dangers of under-sizing

  • Mushrooming of the device
  • Dislodgment & Embolisation
  • Residual shunts
  • Thrombosis over metal gutter created by intending device

Dangers of over sizing

  • Aortic erosion
  • AV blocks

Newer modalities  for ASD imaging

Intra cardiac echo and real time 3D TEE will facilitate the ASD device procedures
Image source : Heart 2010;96:1409e1417

Final message


ASD device closure is rapidly gaining  popularity . Contraindications are declining . More and more young cardiologists want to  indulge in this    play . Though  more children are getting benefited in this non surgical modality ,  complications are also increasing .

Small centers should not be allowed to carry out these procedures. Fortunately  cost of  device   acts as a major  deterrent  . A few centers (one or two per state )   is to be developed for high degree of expertise .

Without mastering the art of TEE never touch the ASD device .

The most critical step  in ASD device closure lies before the procedure  and   . . . it is often  outside the cath lab !

Always refer  large defects and  complex  ASDs  which are adjacent to Aorta and AV  to a good surgeon .Get an operative photograph of the defect and re analyse whether device would have been possible in retrospect .

References

1.An important study  about sizing of ASD  prior to closure  from Sri Chitra Institute . ( This study vouch for TEE for ASD size estimation )

2.Ann Pediatr Cardiol. 2011 Jan-Jun; 4(1): 28–33.

3.Sizing Balloon-Induced Tear of the Atrial Septum 

4.http://www.invasivecardiology.com/article/4716?page=2

5.J Teh Univ Heart Ctr 2011;6(2):79-84

6.Echocardiography in cath lab -An Excellent review in Heart

Further reading

Related Post in this  site. (ASD closure lagging behind surgery ?)


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It was those great  years  1974 -1976.  Even before the concept of  PTCA was born, few  committed cardiologists  of New  Orleans were on a mission. Closing the ASD in cath lab. They  achieved it successfully with a umbrella device.

 

But 35 years later as on 2010 ,the concept though proven still struggles to prove itself.

Link to related article .

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