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Posts Tagged ‘ASD device closure’

The branching pattern of the human cardio-vascular tree is as unique as one’s fingerprint. One such hugely variable anatomy is the SA nodal blood supply.

Certain salient features

  • Variation can be seen in origin, course, and termination.
  • Now it is estimated to arise from RCA in 70% (Moved up from 55% in old studies )
  • From LCX (25%)
  • Dual SA node supply(5%)
  • Direct from Aorta

It is heartening to find this good anatomical review on this topic.

A) From the Right Coronary Artery; (B) From the Left Circumflex Artery (proximal); (C) From the Left Circumflex Artery (distal); (D) From the Left Coronary Artery; (E) From the Aorta; (F) Dual origin from the Right Coronary Artery and the Left Circumflex Artery. Image source : Vikse J, PLoS ONE 11(2): e0148331

Implication for the surgeon

The whereabouts of this tiny, yet important artery is critical to the surgeons’ as they incise and explore the atrial roof. (A gateway, that gives access to so many cardiac surgeries) The SA nodal artery mostly goes retro caval but it can be peri-caval or even anterior to SVC.

This image shows (a,b,c) the course in relation to SVC, Developmentally as the venous pole go posteriorly to fix the SA artery behind it.Image source : Vikse J, PLoS ONE 11(2): e0148331

For the Interventional cardiologist

A rare but distinct mechanical compression of SA node artery is reported with large ASD closure device. The plane of compression is usually occurring in the superior aspect of IAS when the SA node artery cross over the RA to reach the SA node. Should be suspected whenever unusual bradycardia occurs during the manipulation of the device or just after deployment. Always mind the delicate gap  between the antero superior rim and disc where SA nodal artery is likely to trespass.

AV node Ischemia with ASD device

With precise imaging modalities, new secrets are emerging. Additional AV node arteries from proximal RCA is documented.This is a surprising learning point for us. This artery is referred to as the right superior descending artery, which provides an alternative blood supply to the AV node from the proximal right coronary artery. The transient compromise of this hitherto unknown AV nodal twigs by the ASD device cause AV blocks. With this new info, we also got an answer to one more lingering question, why would disproportionate bradycardias are observed in inferior MI even when distal RCA is flowing well. We can’t blame high vagal tone always.

SA node compression by ASD device amplatzer

A CT angiogram showing how the ASD device encroaches the SA node artery. Image Source:Tsunehisa Yamamoto JACC 2016 (Linkedbelow)

The original article has an excellent video clipping of how an ASD device hugs the SA node at the superior edge of ASD.

Final message

Human anatomy is not the subject meant to be read in the first-year medical school cadavers, & forget thereafter. Surprisingly. the field of anatomy is also evolving with new mysteries exposed by modern imaging.SA nodal arterial blood supply is one such interesting aspect of cardiac anatomy. Young fellows in cardiology shall pursue further anatomical dark spaces in the heart (One such topic is how cardiac lymphatics compete with the venous system in draining cardiac interstitium)

Reference

Vikse J, Henry BM, Roy J, RamakrishnanPK, Hsieh WC, Walocha JA, et al. (2016) AnatomicalVariations in the Sinoatrial Nodal Artery: A Meta-Analysis and Clinical Considerations. PLoS ONE 11(2): e0148331

It’s gratifying a unique and committed group exclusively doing research in Anatomy. It Department of Anatomy, Jagiellonian University Medical College, Krakow Poland.

http://www.eba.cm.uj.edu.pl/

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asd-closure-device-www-drsvenkatesan-com

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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