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{{CMG}}{{SI}}
__NOTOC__
{{Blalock-Taussig shunt}}


{{CMG}}; '''Associate Editor-In-Chief:''' {{Usman Ali Akbar}}
'''''Synonyms and keywords:''''' Blalock Taussig Procedure, Procedure, Blalock-Taussig, Subclavian Pulmonary Artery Shunt, Blue Baby Operations, Modified Blalock-Taussig Procedure


==Overview==
==Overview==
The '''Blalock-Taussig shunt''' is a surgical procedure that are done as palliative procedures for [[cyanotic heart defect]]s which are common causes of [[blue baby syndrome]]. In modern surgery, this procedure is temporarily used to direct blood flow to the lungs and relieve cyanosis while the infant is waiting for corrective surgery. One branch of the [[subclavian artery]] (Arteria subclavia) or [[carotid artery]] (Arteria carotis) is separated and connected with the [[pulmonary artery]] (Arteria pulmonalis). The [[Human lung|lung]] receives more blood with low [[oxygenation]] from the body. The first area of application was [[tetralogy of Fallot]]. This procedure has been modified into modified Blalock-Taussing Shunt (mBTS). In this modified procedure a graft from innominate artery or subclavian artery is placed to the corresponding pulmonary artery. 


== Historical Prospective ==
The '''Blalock-Taussig shunt''' is a [[Palliative treatment|palliative]] [[surgical procedure]] for [[cyanotic heart defect]]s. This [[procedure]] is used to deviate [[blood flow]] to the [[lungs]] from [[systemic circulation]] to relieve [[cyanosis]] while a definitive [[corrective surgery]] can be performed at a later time. A connection is usually made between the [[subclavian artery]] and [[pulmonary artery]]. Usually, two types of [[Shunt (medical)|shunts]] are used: classic or original Blalock-Taussig shunt and modified Blalock Taussig shunt. The classic/original BT shunt has been modified into modified Blalock-Taussig Shunt (mBTS). In this modified [[procedure]], a [[graft]] from an [[innominate artery]] or [[subclavian artery]] is placed to the corresponding [[pulmonary artery]]. This type of BT shunt has superior [[Prognosis|prognostic]] value over the classical shunt leading to a greater rate of shunt patency in 3-5 years as compared to the classic or original BT Shunt.
[[File:Original-blalock-taussig-shunt-creative-commons.png|thumb|Original Blalock-Taussig shunt diagram,Case courtesy of Dr Laurent Bilodeau, https://radiopaedia.org/cases/74774">rID: 74774|left|211x211px]]
 
== Historical Perspective ==
 
=== Classic or Original Shunt ===


=== Original Shunt ===
* The classic or original BT shunt [[procedure]] was named after a [[surgeon]] in Baltimore, [[Alfred Blalock]] (1899–1964), and a [[cardiologist]] in Baltimore/Boston, [[Helen B. Taussig]] (1898–1986), who along with Blalock's African American [[laboratory]] technician [[Vivien Thomas]] (1910–1985), developed and described the [[procedure]].  
The original procedure was named for [[Alfred Blalock]], surgeon, Baltimore, (1899–1964) and [[Helen B. Taussig]], cardiologist, Baltimore/Boston, (1898–1986) who, along with Blalock's African American laboratory technician [[Vivien Thomas]] (1910–1985), developed the procedure. Taussig, who treated hundreds of infants and children with this disorder, had observed that children with a cyanotic heart defect and a [[patent ductus arteriosus]] (PDA) lived longer than those without the PDA. It therefore seemed to her that a shunt which mimicked the function of a PDA might relieve the tetralogy patients' poor oxygenation. In 1943, having broached the possibility of a surgical solution to Dr. Robert Gross of Boston  without success, Dr. Taussig approached Blalock and Thomas in their Hopkins laboratory in 1943. {{cite book | last = Thomas | first = Vivien | title = Partners of the heart : Vivien Thomas and his work with Alfred Blalock : an autobiography | publisher = University of Pennsylvania Press | location = Philadelphia | year = 1985 | isbn = 0812216342 }}
* Taussig noticed that the [[children]] with [[cyanosis]] along with [[congenital heart disease]] accompanied by [[patent ductus arteriosus]] have a longer lifetime than those without [[Patent ductus arteriosus|PDA]].
*In 1943, Dr. Taussig approached Blalock and Thomas in their Hopkins [[laboratory]] to work on this [[shunt]] as it was hypothesized that a [[shunt]] mimicking [[PDA]] can relieve the [[cyanosis]] and improve [[oxygenation]] in [[congential]] [[cyanotic diseases]].<ref>https://www.upenn.edu/pennpress/book/1904.html</ref>
 
[[File:Original-blalock-taussig-shunt-creative-commons.png|thumb|200px|none|Original Blalock-Taussig shunt diagram. [https://radiopaedia.org/cases/74774 Source: Dr. Laurent Bilodeau.]]]


=== Modified Blalock-Taussig Shunt ===
=== Modified Blalock-Taussig Shunt ===
[[File:Modified-blalock-taussig-shunt-creative-commons.png|left|thumb|271x271px|'''Modified Blalock-Taussig shunt diagram Case courtesy of Dr Laurent Bilodeau,"https://radiopaedia.org/".From the case https://radiopaedia.org/cases/74773 ,rID: 74773''']]A modified method of inserting a shunt was developed in 1962  by Klinner using teflon as prosthetic graft material between the subclavian artery and the pulmonary artery is used to prevent scarring of the subclavian artery. <ref name="pmid144570412">{{cite journal| author=KLINNER W, PASINI M, SCHAUDIG A| title=[Anastomosis between systemic and pulmonary arteries with the aid of plastic prostheses in cyanotic heart diseases]. | journal=Thoraxchirurgie | year= 1962 | volume= 10 | issue=  | pages= 68-75 | pmid=14457041 | doi=10.1055/s-0028-1096482 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14457041  }}</ref>
*In 1962, a modified method of inserting a [[shunt]] was developed by Klinner using [[teflon]] as a [[Prosthetic|prosthetic graft]] material between the [[subclavian artery]] and the [[pulmonary artery]] in order to prevent [[scarring]] of the [[subclavian artery]].<ref name="pmid144570412">{{cite journal| author=KLINNER W, PASINI M, SCHAUDIG A| title=[Anastomosis between systemic and pulmonary arteries with the aid of plastic prostheses in cyanotic heart diseases]. | journal=Thoraxchirurgie | year= 1962 | volume= 10 | issue=  | pages= 68-75 | pmid=14457041 | doi=10.1055/s-0028-1096482 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14457041  }}</ref><ref name="pmid19040408" /><ref name="pmid28701598" />
<br />


== Indications ==
[[File:Modified-blalock-taussig-shunt-creative-commons.png|thumb|200px|none|Modified Blalock-Taussig shunt diagram. [https://radiopaedia.org/cases/74773 Source: Dr. Laurent Bilodeau.]]]


* Tricuspid atresia
== Classification  ==
* Teratology of Fellot
* Ebstein's Anomly
* Hypoplastic Left Heart syndrome
* Pulmonary atresia


== Procedure ==
=== Classic/Original Blalock-Taussig Shunt ===


=== Classic/Orginal Blalock-Taussig Shunt ===
* For classic Blalock-Taussig shunt, an end-to-end [[anastomosis]] opposite to the [[aortic arch]] is performed between the [[subclavian]] and [[Pulmonary artery|pulmonary arteries]] to minimize the [[kinking]] of [[subclavian artery]] as it crosses [[Aorta|aortic]] prominence.<ref name="pmid28701598">{{cite journal| author=Kiran U, Aggarwal S, Choudhary A, Uma B, Kapoor PM| title=The blalock and taussig shunt revisited. | journal=Ann Card Anaesth | year= 2017 | volume= 20 | issue= 3 | pages= 323-330 | pmid=28701598 | doi=10.4103/aca.ACA_80_17 | pmc=5535574 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28701598  }} </ref>
 
* For classic Blalock-Taussig shunt end to end anastomosis between the subclavian and pulmonary arteries is performed on opposite to the aortic arch to minimize the kinking of subclavian artery as it crosses aortic prominence


{| class="wikitable sortable"
{| class="wikitable sortable"
|+Classic/Original Blalock-Taussig Shunt
|+Classic/Original Blalock-Taussig Shunt
!Advantages  
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Advantages}}
!Disadvantages  
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|-
|The relative diameter of subclvian artery prevents excessive blood flow to lungs
|The relative [[diameter]] of [[subclavian artery]] prevents excessive [[blood flow]] to [[lungs]]
|Thrombosis of shunt due less diameter
|[[Thrombosis]] of [[shunt]] due to less [[diameter]]
|-
|-
|Easily Reversible
|Easily reversible
|Dissection
|Risk of [[dissection (medical)|dissection]]
|-
|-
|Increased rate of anastomosis growth
|Increased [[rate]] of [[anastomosis]] [[growth]]
|Subclavian artery is lost during the procedure  
|[[Subclavian artery]] is lost during the [[procedure]]
|}
|}


=== Modified Blalock Taussig Shunt ===
=== Modified Blalock Taussig Shunt ===
It is the most commonly used procedure now a days. First described and performed by Klinner et. al in 1962, this procedure hold superb prognosis over classic one. An Interposition PTFE or Gore-Tex graft is placed between the subclvian artery and the pulmonary artery. Hence no scarring of subclavian artery results.  
 
*In 1962, it was first described and performed by Klinner et al.
*It is more commonly used [[procedure]] and holds a better [[prognosis]] compared to the classic procedure.
*An [[Interposition]] PTFE or Gore-Tex [[graft]] is placed between the [[subclavian artery]] and the [[pulmonary artery]]. As a result, there's no [[scarring]] of [[subclavian artery]].<ref name="pmid28701598">{{cite journal| author=Kiran U, Aggarwal S, Choudhary A, Uma B, Kapoor PM| title=The blalock and taussig shunt revisited. | journal=Ann Card Anaesth | year= 2017 | volume= 20 | issue= 3 | pages= 323-330 | pmid=28701598 | doi=10.4103/aca.ACA_80_17 | pmc=5535574 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28701598  }} </ref>
 
{| class="wikitable"
{| class="wikitable"
|+Modified Blalock Taussig Shunt  
|+Modified Blalock Taussig Shunt  
!Advantages  
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Advantages}}
!Disadvantages
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|-
|It can be done on the same side of the arch
|It can be done on the same side of the [[aortic arch]]
|Thrombosis
|[[Thrombosis]]
|-
|-
|More patency than Classic BT shunt i.e >90 % at 2 years  
|More [[patency]] than Classic BT shunt i.e >90 % at 2 years
|Pseudoaneurysm  
|[[Pseudoaneurysm]]
|-
|-
|Pulmonary artery is less disorted
|[[Pulmonary artery]] is less distorted
|Chylothorax, Chylopericardium, chylous ascites
|[[Chylothorax]], [[Chylopericardium|Chylopericardium,]] [[Ascites|chylous ascites]]
|}
|}


* <br />
== Goals of BT shunt ==
*The ultimate endpoint goals of BT shunt are as follows:
** To stabilize the [[preload]], hence preventing hemodilution.
** To maintain the [[systemic vascular resistance]] ([[afterload]]) hence, adequate [[diastolic pressure]] to maintain [[coronary]] [[perfusion]].
** Increase the [[blood flow]] to the [[pulmonary vasculature]] in a supervised manner.
 
== Indications ==
*Following is a list of indications for Blalock-Taussig shunt:
**[[Tricuspid atresia]]
**[[Tetralogy of Fallot:|Tetralogy of Fallot]]
**[[Ebstein's anomaly of the tricuspid valve|Ebstein's Anomaly]]
**Hypoplastic Left Heart syndrome
**[[Pulmonary atresia]]
**Inadequate [[pulmonary arteries]]
 
== Risk Factors ==
 
* Following multiple [[risk factors]] have been identified to be associated with high [[morbidity]] and [[mortality]] in [[neonates]]:<ref name="pmidhttps://doi.org/10.1016/j.jamcollsurg.2012.12.027">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.1016/j.jamcollsurg.2012.12.027 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }} </ref><ref name="pmidhttps://doi.org/10.1016/j.athoracsur.2011.02.030">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.1016/j.athoracsur.2011.02.030 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }} </ref>
** [[Sternal]] approach for MBTS construction
** Univentricular [[heart]]
** Complicated [[surgery]] ([[Cardiopulmonary bypass|CABG]])
** [[Weight]] <3 kg
** Pre-operative [[ventilation]] support
** Pre-operative [[acidosis]] and [[shock]]
** Use of [[Innominate artery]]-PA [[shunt]]
** [[Diagnosis]] of [[Ebstein's Anomaly of the Tricuspid Valve|Ebstein's Anomaly]]
 
== Preparation for BT Shunt ==
*To perform a BT [[shunt]] following pre-operative preparation is done:
**[[Preoperative assessment|Preoperative]] [[psychological]] [[counseling]] of the [[patient]]
**[[Preoperative assessment|Preoperative]] fasting
**[[Preoperative assessment|Preoperative]] [[Medication|medications]]
*[[Anesthesia]] induction is based on the following [[patient]] and [[surgery]]-related factors:
 
=== Patient-Related Factors ===
 
* [[Diagnosis]] of a relative [[Congenital Abnormalities|congenital]] [[cardiac]] [[anomaly]]
* [[Age]] of the [[patient]]
* [[Weight]] <3 kg leads to a high [[Mortality rate|mortality]] and [[morbidity]]
*[[Premature birth|Premature infants]]
* Any non-[[cardiac]] coexisting [[congenital anomaly]] such as:
**[[Tracheoesophageal fistula]]
**[[Cleft lip and palate]]
**[[Renal]] anomalies
**[[Skeletal]] defects
*[[Atlanto-axial joint|Atlantoaxial instability]] or [[subluxation]] in [[Down syndrome]] should be considered while managing the [[airway]].
*[[Fatigue]], and/or [[dyspnea]] on feeding or any other factor showing [[exercise intolerance]].
* Use of [[medications]] that can lead to an increase in operative [[mortality]] such as:
**[[Aspirin|Aspirin]]
**[[Warfarin]]
**[[Antidepressants|Anti-depressants]]
**[[Diuretic|Diuretics]]
**[[Angiotensin converting enzyme inhibitors]] ([[ACEI]])
**[[Antiarrhythmics]]
* [[Congenital]] [[conditions]] such as [[subglottic stenosis]] that can lead to difficulty in gaining access for [[intubation]].
* Optimal [[right ventricular]] function
 
=== Factors Related to Surgical Procedure ===
 
* Complex [[lesions]] lead to high overall and in-hospital [[mortality]].
* Duration of the [[surgery]]
* [[Cardiovascular anomalies]] that can lead to complexity of the [[procedure]] such as [[Aortic arch anomalies|aortic arch]] [[anomaly]] or presence of [[aberrant subclavian artery]].
* [[Injury]] to the [[recurrent laryngeal nerve]] or [[phrenic nerve]] during the [[procedure]].
* Nature and approach of the [[cardiac surgery]] e.g., [[cardiopulmonary bypass]], [[median sternotomy|sternotomy]] or [[thoracotomy]].
 
=== Approach ===
 
* Left lateral position is used for the right-sided modified Blalock-Taussig shunt (mBTS), and the right lateral position is used for left-sided mBTS.
* The approach used is usually [[thoracotomy]].
* [[Sternotomy]] is performed for the central [[shunts]].
 
== Complications ==
* The immediate [[Post operative complications|post-operative complications]] include:<ref name="pmid19040408">{{cite journal| author=Yuan SM, Shinfeld A, Raanani E| title=The Blalock-Taussig shunt. | journal=J Card Surg | year= 2009 | volume= 24 | issue= 2 | pages= 101-8 | pmid=19040408 | doi=10.1111/j.1540-8191.2008.00758.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19040408  }} </ref>
** Development of [[chylothorax]], [[chylopericardium]] and [[Ascites|chylous ascites]]
**[[Phrenic nerve|Phrenic nerve resection]] leading to [[diaphragmatic paralysis]]
**[[Anemia]]
**[[Congestive heart failure|Congestive heart failure]] resulting from excessive [[blood flow]]
** Modified PTFE [[grafts]] can result in the formation of [[seroma]] or [[shunt]] [[occlusion]] due to [[hyperplasia]] of [[neo-intima]]
**[[Stenosis]] of [[innominate artery]]
**[[Shunt]] [[infection]] resulting in [[sepsis]]
 
[[File:Unilateral-pulmonary-oedema-blalock-taussig-shunt-in-pulmonary-atresia-with-ventricular-septal-defect-1.jpg|thumb|220px|none| Unilateral pulmonary edema, Blalock-Taussig shunt in pulmonary atresia with a ventricular septal defect. [https://radiopaedia.org/cases/18390 Source: Dr. Charlie Chia-Tsong.]]]
 
=== Management of Complications ===
 
==== Shunt failure ====
* [[Failure]] of the [[shunt]] is the most immediate risk during the post-operative period which can lead to a drop in [[oxygen saturation]] secondary due to [[Thrombosis|shunt thrombosis]] or [[kinking]].
* [[Shunt]] [[failure]] is a [[surgical emergency]] and should be managed as follows:
**[[Anticoagulant|Anticoagulation]] should be started promptly with [[heparin]]. It should be administered again if there is less risk of [[bleeding]] usually 4 hours post-op (when the drainage of the [[chest]] shows <3ml/kg/h and aPTT is <60s). [[Heparin-induced thrombocytopenia|Heparin induced thrombocytopenia]] can occur and should be managed accordingly.
** [[Patient]] is put on [[aspirin]] which is usually started at 3-5 mg/kg (max. dose 75mg) OD.
**[[Heparin]] should be continued until there is a second [[dose]] of [[aspirin]].
 
==== Blockage of BT shunt ====
 
* [[Blockage]] or [[shunt]] [[thrombosis]] is another [[surgical emergency]] with a reported [[incidence]] of 12%.
* If there's any recent onset [[Murmurs|murmur]] or a significant drop in [[oxygen saturation]], it must be investigated.
* Operative management is usually required and the [[shunt]] is usually repaired or replaced if necessary.
 
=== High pulmonary blood flow ===


* The appropriate size of BT [[shunt]] is very important to prevent the long term [[complications]] regarding high [[pulmonary]] [[blood flow]] or high [[oxygen saturation]].
* [[Chest X-ray|Chest X Ray]] usually shows [[edematous]] [[lungs]] with low mixed [[venous saturation]], rising [[lactate]] levels or signs of [[right heart failure]], [[Diastolic pressure|systemic diastolic pressure]] may be low, persistent [[metabolic acidosis]] leading to "pink [[patient]]" and [[Pulmonary hemorrhage|pulmonary hemorrhage]]. 


===== Causes =====


*High [[FiO2]]
*[[PDA]] still open leading to excessive [[blood]] delivery to the [[lungs]]
*Large [[shunt]] [[diameter]]


===== Treatment =====
Following treatment is instituted:
* For mild to moderate [[symptoms]], [[fluid resuscitation]] and [[diuretics]] are given. Permissive [[hypercapnia]] and lowering of [[FiO2]] is done.
* For severe [[symptoms]], [[systemic vascular resistance]] and [[pulmonary vascular resistance]] is adjusted.
* Cases refractory to [[medical]] management are usually treated with a [[surgical]] approach that involves [[pulmonary artery]] banding or clamping.


== Prognosis ==
*Modified Blalock-Taussig shunt has a superior [[Prognosis|prognostic]] value over classic Blalock-Taussig Shunts. Following [[prognostic]] factors are compared between the two [[procedures]] in multiple studies:<ref name="pmid9855103">{{cite journal| author=Al Jubair KA, Al Fagih MR, Al Jarallah AS, Al Yousef S, Ali Khan MA, Ashmeg A | display-authors=etal| title=Results of 546 Blalock-Taussig shunts performed in 478 patients. | journal=Cardiol Young | year= 1998 | volume= 8 | issue= 4 | pages= 486-90 | pmid=9855103 | doi=10.1017/s1047951100007150 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9855103  }} </ref><ref name="pmid16337132">{{cite journal| author=Kim HK, Kim WH, Kim SC, Lim C, Lee CH, Kim SJ| title=Surgical strategy for pulmonary coarctation in the univentricular heart. | journal=Eur J Cardiothorac Surg | year= 2006 | volume= 29 | issue= 1 | pages= 100-4 | pmid=16337132 | doi=10.1016/j.ejcts.2005.10.032 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16337132  }} </ref><ref name="pmid3968910">{{cite journal| author=Karpawich PP, Bush CP, Antillon JR, Amato JJ, Marbey ML, Agarwal KC| title=Modified Blalock-Taussig shunt in infants and young children. Clinical and catheterization assessment. | journal=J Thorac Cardiovasc Surg | year= 1985 | volume= 89 | issue= 2 | pages= 275-9 | pmid=3968910 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3968910  }} </ref><ref name="pmid10707705">{{cite journal| author=Kulkarni H, Rajani R, Dalvi B, Gupta KG, Vora A, Kelkar P| title=Effect of Blalock Taussig shunt on clinical parameters, left ventricular function and pulmonary arteries. | journal=J Postgrad Med | year= 1995 | volume= 41 | issue= 2 | pages= 34-6 | pmid=10707705 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10707705  }} </ref><ref name="pmid2441893">{{cite journal| author=Bove EL, Kohman L, Sereika S, Byrum CJ, Kavey RE, Blackman MS | display-authors=etal| title=The modified Blalock-Taussig shunt: analysis of adequacy and duration of palliation. | journal=Circulation | year= 1987 | volume= 76 | issue= 3 Pt 2 | pages= III19-23 | pmid=2441893 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2441893  }} </ref><ref name="pmid3675059">{{cite journal| author=Ullom RL, Sade RM, Crawford FA, Ross BA, Spinale F| title=The Blalock-Taussig shunt in infants: standard versus modified. | journal=Ann Thorac Surg | year= 1987 | volume= 44 | issue= 5 | pages= 539-43 | pmid=3675059 | doi=10.1016/s0003-4975(10)62119-4 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3675059  }} </ref>
** The increase in [[Oxygen saturation|saturation of oxygen]] is greater in the modified [[shunt]] as compared to the classic [[shunt]].
** Modified [[shunt]] has an 88.8% patency rate in 3-5 years. Whereas for the classic [[shunt]], the patency rate is 90% in the first year, 62% in two years, and 78.0% in 3 years.
** The risk of early [[shunt]] [[failure]] is 20.8% in modified and 51.7% in the classic [[shunt]].
** Post-shunt increase in [[Pulmonary artery|pulmonary arterial index]] (mm2/m2) is 158 +/- 21 versus 117 +/- 52 in classic Blalock-Taussig shunt.


[[File:Blalock-taussig-shunt-annotated-image.png|thumb|202px|none|Blalock-taussig shunt annotated image, [https://radiopaedia.org/cases/41040 Source: Dr. Vincent Tatco.]]]


== Alternative Shunts ==


=== Central Shunt ===
* Central [[shunt]] is made by creating an [[anastomosis]] between [[ascending aorta]] and main [[Pulmonary artery|pulmonary artery]].
* A short PTFE conduit for this purpose is used.
* It is also known as Mee's [[shunt]]. <ref name="Eghtesady 2015 pp. 293–305">{{cite journal | last=Eghtesady | first=Pirooz | title=Potts Shunt for Children With Severe Pulmonary Hypertension | journal=Operative Techniques in Thoracic and Cardiovascular Surgery | publisher=Elsevier BV | volume=20 | issue=3 | year=2015 | issn=1522-2942 | doi=10.1053/j.optechstcvs.2016.02.003 | pages=293–305}}</ref>
* [[Internal mammary artery]] is used for this purpose and to create a [[systemic]] to [[pulmonary]] conduit after there has been a [[failure]] of previously used BT [[shunt]].
* It leads to adaptation of [[growth]], and flow, and it also reduces the risk for [[graft]] [[infection]].
{| class="wikitable"
|+
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Advantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|Can be done in small [[children]] with small [[vessels]]
|Can not be performed in [[patients]] without [[patent ductus arteriosus]]
|-
|Distortion of [[pulmonary vessels]] is avoided
|Entry into [[pericardium]]
|-
|Equal [[blood flow]] is provided to both [[lungs]]
|
|-
|Low chance of [[Occlusion|occlusion rate]]
|
|-
|[[Subclavian steal syndrome]] is usually avoided
|
|}
=== Potts shunt ===
* Potts [[shunt]] can be used as an alternative to the classic BT [[shunt]].
* To avoid the consequences of [[right heart failure]], it has been used as an alternative to offload the [[right ventricle]].
* This improves the [[cardiac output]] but the [[oxygen saturation]] is lowered and there is decreased [[oxygen]] delivery to lower [[extremities]].
* Potts [[shunt]] includes a connection that is made between [[descending aorta]] and [[left pulmonary artery]].<ref name="Yuan Jing 2009 pp. 549–557">{{cite journal | last=Yuan | first=Shi-Min | last2=Jing | first2=Hua | title=Palliative procedures for congenital heart defects | journal=Archives of Cardiovascular Diseases | publisher=Elsevier BV | volume=102 | issue=6-7 | year=2009 | issn=1875-2136 | doi=10.1016/j.acvd.2009.04.011 | pages=549–557}}</ref>
{| class="wikitable"
|+
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Advantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|[[Subclavian artery]] is used which has a large [[diameter]] hence, it is easy to perform [[surgery]].
|Increased [[incidence]] of [[pulmonary hypertension]]
|-
|Lower chance of occlusion than CBTS and mBTS
|Increased [[blood flow]] to one [[lung]] while there is kinking of [[pulmonary artery]]
|-
|
|Increased risk of [[congestive heart failure]] <ref name="TRUCCONE BOWMAN MALM GERSONY 1974 pp. 508–511">{{cite journal | last=TRUCCONE | first=NESTOR J. | last2=BOWMAN | first2=FREDERICK O. | last3=MALM | first3=JAMES R. | last4=GERSONY | first4=WELTON M. | title=Systemic-Pulmonary Arterial Shunts in the First Year of Life | journal=Circulation | publisher=Ovid Technologies (Wolters Kluwer Health) | volume=49 | issue=3 | year=1974 | issn=0009-7322 | doi=10.1161/01.cir.49.3.508 | pages=508–511}}</ref>
|}
=== '''Waterston shunt''' ===
* It is made by connecting the [[ascending aorta]] and [[right pulmonary artery]]. 
* It has not been clinically performed now due to increased risk of [[congestive heart failure]], [[pulmonary hypertension]], and kinking of the [[pulmonary artery]].
=== Cooley Shunt ===
* It is an [[Anastomosis|intrapericardial anastomosis]] between [[ascending aorta]] and the right [[pulmonary artery]]. 
* Right anterolateral [[thoracotomy]] approach is used.
{| class="wikitable"
|+
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Advantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|Use of right anterolateral [[incision]] for all approaches - [[Mediastinal|Mediastinal dissection]] is avoided
|Improper size of the [[shunt]] can lead to [[right heart failure]] and [[pulmonary congestion]]
|-
|Total repair can be done after this [[shunt]] in future
|Risk of [[intracardiac]] [[adhesions]]
|-
|
|Complexity of the [[procedure]]
|}


<br />
==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
[[Category:Up-To-Date]]


[[Category:Cardiology]]
[[Category:Cardiology]]
[[Category:Surgery]]
[[Category:Surgery]]

Latest revision as of 13:45, 20 October 2020

Blalock-Taussig shunt Microchapters

Overview

Historical Perspective

Classification

Goals of BT shunt

Indications

Risk Factors

Preparation for BT Shunt

Complications

Prognosis

Alternative Shunts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Usman Ali Akbar, M.B.B.S.[2]

Synonyms and keywords: Blalock Taussig Procedure, Procedure, Blalock-Taussig, Subclavian Pulmonary Artery Shunt, Blue Baby Operations, Modified Blalock-Taussig Procedure

Overview

The Blalock-Taussig shunt is a palliative surgical procedure for cyanotic heart defects. This procedure is used to deviate blood flow to the lungs from systemic circulation to relieve cyanosis while a definitive corrective surgery can be performed at a later time. A connection is usually made between the subclavian artery and pulmonary artery. Usually, two types of shunts are used: classic or original Blalock-Taussig shunt and modified Blalock Taussig shunt. The classic/original BT shunt has been modified into modified Blalock-Taussig Shunt (mBTS). In this modified procedure, a graft from an innominate artery or subclavian artery is placed to the corresponding pulmonary artery. This type of BT shunt has superior prognostic value over the classical shunt leading to a greater rate of shunt patency in 3-5 years as compared to the classic or original BT Shunt.

Historical Perspective

Classic or Original Shunt

Original Blalock-Taussig shunt diagram. Source: Dr. Laurent Bilodeau.

Modified Blalock-Taussig Shunt

Modified Blalock-Taussig shunt diagram. Source: Dr. Laurent Bilodeau.

Classification

Classic/Original Blalock-Taussig Shunt

Classic/Original Blalock-Taussig Shunt
Advantages Disadvantages
The relative diameter of subclavian artery prevents excessive blood flow to lungs Thrombosis of shunt due to less diameter
Easily reversible Risk of dissection
Increased rate of anastomosis growth Subclavian artery is lost during the procedure

Modified Blalock Taussig Shunt

Modified Blalock Taussig Shunt
Advantages Disadvantages
It can be done on the same side of the aortic arch Thrombosis
More patency than Classic BT shunt i.e >90 % at 2 years Pseudoaneurysm
Pulmonary artery is less distorted Chylothorax, Chylopericardium, chylous ascites

Goals of BT shunt

Indications

Risk Factors

Preparation for BT Shunt

Patient-Related Factors

Factors Related to Surgical Procedure

Approach

  • Left lateral position is used for the right-sided modified Blalock-Taussig shunt (mBTS), and the right lateral position is used for left-sided mBTS.
  • The approach used is usually thoracotomy.
  • Sternotomy is performed for the central shunts.

Complications

Unilateral pulmonary edema, Blalock-Taussig shunt in pulmonary atresia with a ventricular septal defect. Source: Dr. Charlie Chia-Tsong.

Management of Complications

Shunt failure

Blockage of BT shunt

High pulmonary blood flow

Causes
Treatment

Following treatment is instituted:

Prognosis

  • Modified Blalock-Taussig shunt has a superior prognostic value over classic Blalock-Taussig Shunts. Following prognostic factors are compared between the two procedures in multiple studies:[7][8][9][10][11][12]
    • The increase in saturation of oxygen is greater in the modified shunt as compared to the classic shunt.
    • Modified shunt has an 88.8% patency rate in 3-5 years. Whereas for the classic shunt, the patency rate is 90% in the first year, 62% in two years, and 78.0% in 3 years.
    • The risk of early shunt failure is 20.8% in modified and 51.7% in the classic shunt.
    • Post-shunt increase in pulmonary arterial index (mm2/m2) is 158 +/- 21 versus 117 +/- 52 in classic Blalock-Taussig shunt.
Blalock-taussig shunt annotated image, Source: Dr. Vincent Tatco.

Alternative Shunts

Central Shunt

Advantages Disadvantages
Can be done in small children with small vessels Can not be performed in patients without patent ductus arteriosus
Distortion of pulmonary vessels is avoided Entry into pericardium
Equal blood flow is provided to both lungs
Low chance of occlusion rate
Subclavian steal syndrome is usually avoided

Potts shunt

Advantages Disadvantages
Subclavian artery is used which has a large diameter hence, it is easy to perform surgery. Increased incidence of pulmonary hypertension
Lower chance of occlusion than CBTS and mBTS Increased blood flow to one lung while there is kinking of pulmonary artery
Increased risk of congestive heart failure [15]

Waterston shunt

Cooley Shunt

Advantages Disadvantages
Use of right anterolateral incision for all approaches - Mediastinal dissection is avoided Improper size of the shunt can lead to right heart failure and pulmonary congestion
Total repair can be done after this shunt in future Risk of intracardiac adhesions
Complexity of the procedure

References

  1. ↑ https://www.upenn.edu/pennpress/book/1904.html
  2. ↑ KLINNER W, PASINI M, SCHAUDIG A (1962). "[Anastomosis between systemic and pulmonary arteries with the aid of plastic prostheses in cyanotic heart diseases]". Thoraxchirurgie. 10: 68–75. doi:10.1055/s-0028-1096482. PMID 14457041.
  3. ↑ 3.0 3.1 Yuan SM, Shinfeld A, Raanani E (2009). "The Blalock-Taussig shunt". J Card Surg. 24 (2): 101–8. doi:10.1111/j.1540-8191.2008.00758.x. PMID 19040408.
  4. ↑ 4.0 4.1 4.2 Kiran U, Aggarwal S, Choudhary A, Uma B, Kapoor PM (2017). "The blalock and taussig shunt revisited". Ann Card Anaesth. 20 (3): 323–330. doi:10.4103/aca.ACA_80_17. PMC 5535574. PMID 28701598.
  5. ↑ Schmoldt A, Benthe HF, Haberland G (1975). "Digitoxin metabolism by rat liver microsomes". Biochem Pharmacol. 24 (17): 1639–41. PMID https://doi.org/10.1016/j.jamcollsurg.2012.12.027 Check |pmid= value (help).
  6. ↑ Schmoldt A, Benthe HF, Haberland G (1975). "Digitoxin metabolism by rat liver microsomes". Biochem Pharmacol. 24 (17): 1639–41. PMID https://doi.org/10.1016/j.athoracsur.2011.02.030 Check |pmid= value (help).
  7. ↑ Al Jubair KA, Al Fagih MR, Al Jarallah AS, Al Yousef S, Ali Khan MA, Ashmeg A; et al. (1998). "Results of 546 Blalock-Taussig shunts performed in 478 patients". Cardiol Young. 8 (4): 486–90. doi:10.1017/s1047951100007150. PMID 9855103.
  8. ↑ Kim HK, Kim WH, Kim SC, Lim C, Lee CH, Kim SJ (2006). "Surgical strategy for pulmonary coarctation in the univentricular heart". Eur J Cardiothorac Surg. 29 (1): 100–4. doi:10.1016/j.ejcts.2005.10.032. PMID 16337132.
  9. ↑ Karpawich PP, Bush CP, Antillon JR, Amato JJ, Marbey ML, Agarwal KC (1985). "Modified Blalock-Taussig shunt in infants and young children. Clinical and catheterization assessment". J Thorac Cardiovasc Surg. 89 (2): 275–9. PMID 3968910.
  10. ↑ Kulkarni H, Rajani R, Dalvi B, Gupta KG, Vora A, Kelkar P (1995). "Effect of Blalock Taussig shunt on clinical parameters, left ventricular function and pulmonary arteries". J Postgrad Med. 41 (2): 34–6. PMID 10707705.
  11. ↑ Bove EL, Kohman L, Sereika S, Byrum CJ, Kavey RE, Blackman MS; et al. (1987). "The modified Blalock-Taussig shunt: analysis of adequacy and duration of palliation". Circulation. 76 (3 Pt 2): III19–23. PMID 2441893.
  12. ↑ Ullom RL, Sade RM, Crawford FA, Ross BA, Spinale F (1987). "The Blalock-Taussig shunt in infants: standard versus modified". Ann Thorac Surg. 44 (5): 539–43. doi:10.1016/s0003-4975(10)62119-4. PMID 3675059.
  13. ↑ Eghtesady, Pirooz (2015). "Potts Shunt for Children With Severe Pulmonary Hypertension". Operative Techniques in Thoracic and Cardiovascular Surgery. Elsevier BV. 20 (3): 293–305. doi:10.1053/j.optechstcvs.2016.02.003. ISSN 1522-2942.
  14. ↑ Yuan, Shi-Min; Jing, Hua (2009). "Palliative procedures for congenital heart defects". Archives of Cardiovascular Diseases. Elsevier BV. 102 (6–7): 549–557. doi:10.1016/j.acvd.2009.04.011. ISSN 1875-2136.
  15. ↑ TRUCCONE, NESTOR J.; BOWMAN, FREDERICK O.; MALM, JAMES R.; GERSONY, WELTON M. (1974). "Systemic-Pulmonary Arterial Shunts in the First Year of Life". Circulation. Ovid Technologies (Wolters Kluwer Health). 49 (3): 508–511. doi:10.1161/01.cir.49.3.508. ISSN 0009-7322.
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