Blalock-Taussig shunt: Difference between revisions

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==Overview==
==Overview==


The '''Blalock-Taussig shunt''' is a [[Palliative treatment|palliative]] [[surgical procedure]] done 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 i.e 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 [[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.
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.


== Historical Perspective ==
== Historical Perspective ==
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*In 1962, it was first described and performed by Klinner et al.
*In 1962, it was first described and performed by Klinner et al.
*It is the most commonly used [[procedure]] nowadays and holds a much better [[prognosis]] over the classic one.
*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]]. Hence, 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>
*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"
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== Goals of BT shunt ==
== Goals of BT shunt ==
*The ultimate endpoint goals of BT shunt are as follows:
*The ultimate endpoint goals of BT shunt are as follows:
** To stabilize the preload hence preventing hemodilution.  
** To stabilize the [[preload]], hence preventing hemodilution.  
** To maintain systemic vascular resistance (afterload) hence, adequate diastolic pressure to maintain coronary perfusion.
** 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.
** Increase the [[blood flow]] to the [[pulmonary vasculature]] in a supervised manner.


== Indications ==
== Indications ==
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**[[Tetralogy of Fallot:|Tetralogy of Fallot]]
**[[Tetralogy of Fallot:|Tetralogy of Fallot]]
**[[Ebstein's anomaly of the tricuspid valve|Ebstein's Anomaly]]
**[[Ebstein's anomaly of the tricuspid valve|Ebstein's Anomaly]]
**[[Hypoplastic Left Heart syndrome]]
**Hypoplastic Left Heart syndrome
**[[Pulmonary atresia]]
**[[Pulmonary atresia]]
**Inadequate pulmonary arteries
**Inadequate [[pulmonary arteries]]


== Risk Factors ==
== 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>
* 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
** [[Sternal]] approach for MBTS construction
** Univentricular heart
** Univentricular [[heart]]
** Complicated surgery ([[Cardiopulmonary bypass|CABG]])
** Complicated [[surgery]] ([[Cardiopulmonary bypass|CABG]])
** Weight <3 kg
** [[Weight]] <3 kg
** Pre-operative [[ventilation]] support
** Pre-operative [[ventilation]] support
** Pre-operative [[acidosis]] and [[shock]]
** Pre-operative [[acidosis]] and [[shock]]
** Use of [[Innominate artery]]-PA shunt
** Use of [[Innominate artery]]-PA [[shunt]]
** Diagnosis of [[Ebstein's Anomaly of the Tricuspid Valve|Ebstein's Anomaly]]
** [[Diagnosis]] of [[Ebstein's Anomaly of the Tricuspid Valve|Ebstein's Anomaly]]


== Preparation for BT Shunt ==
== Preparation for BT Shunt ==
*To perform a BT [[shunt]] following pre-operative preparation is done:  
*To perform a BT [[shunt]] following pre-operative preparation is done:  
**[[Preoperative assessment|Preoperative]] psychological counseling of the patient
**[[Preoperative assessment|Preoperative]] [[psychological]] [[counseling]] of the [[patient]]
**[[Preoperative assessment|Preoperative]] fasting
**[[Preoperative assessment|Preoperative]] fasting
**[[Preoperative assessment|Preoperative]] [[Medication|medications]]
**[[Preoperative assessment|Preoperative]] [[Medication|medications]]
*Anesthesia induction is based on the following patient and surgery-related factors:  
*[[Anesthesia]] induction is based on the following [[patient]] and [[surgery]]-related factors:  


=== Patient-Related Factors ===
=== Patient-Related Factors ===


* Diagnosis of a relative [[Congenital Abnormalities|congenital]] cardiac anomaly
* [[Diagnosis]] of a relative [[Congenital Abnormalities|congenital]] [[cardiac]] [[anomaly]]
* Age of the patient  
* [[Age]] of the [[patient]]
* Weight <3 kg leads to a high [[Mortality rate|mortality]] and [[morbidity]]
* [[Weight]] <3 kg leads to a high [[Mortality rate|mortality]] and [[morbidity]]
*[[Premature birth|Premature infants]]
*[[Premature birth|Premature infants]]
* Any non-cardiac coexisting congenital anomaly such as:
* Any non-[[cardiac]] coexisting [[congenital anomaly]] such as:
**[[Tracheoesophageal fistula]]
**[[Tracheoesophageal fistula]]
**[[Cleft lip and palate]]
**[[Cleft lip and palate]]
**Renal anomalies
**[[Renal]] anomalies
**Skeletal defects.
**[[Skeletal]] defects
*[[Atlanto-axial joint|Atlantoaxial instability]] or [[subluxation]] in [[Down syndrome]] should be considered while managing the airway.
*[[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.
*[[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:
* Use of [[medications]] that can lead to an increase in operative [[mortality]] such as:
**[[Aspirin|Aspirin]]
**[[Aspirin|Aspirin]]
**[[Warfarin]]
**[[Warfarin]]
**[[Antidepressants|Anti-depressants]]
**[[Antidepressants|Anti-depressants]]
**[[Diuretic|Diuretics]]
**[[Diuretic|Diuretics]]
**[[Angiotensin converting enzyme (ACE ) inhibitors]]
**[[Angiotensin converting enzyme inhibitors]] ([[ACEI]])
**[[Antiarrhythmics]]
**[[Antiarrhythmics]]
* Congenital conditions such as [[subglottic stenosis]] that can lead to difficulty in gaining access for [[intubation]].
* [[Congenital]] [[conditions]] such as [[subglottic stenosis]] that can lead to difficulty in gaining access for [[intubation]].
* Optimal right ventricular function
* Optimal [[right ventricular]] function


=== Factors Related to Surgical Procedure ===
=== Factors Related to Surgical Procedure ===


* Complex lesions lead to high overall and in-hospital mortality.  
* Complex [[lesions]] lead to high overall and in-hospital [[mortality]].  
* Duration of the surgery  
* 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]].
* [[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.
* [[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]].
* Nature and approach of the [[cardiac surgery]] e.g., [[cardiopulmonary bypass]], [[median sternotomy|sternotomy]] or [[thoracotomy]].


=== Approach ===
=== Approach ===
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* 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.
* 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]].
* The approach used is usually [[thoracotomy]].
* [[Sternotomy]] is performed for the central shunts.
* [[Sternotomy]] is performed for the central [[shunts]].


== Complications ==
== 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>
* 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]]
** Development of [[chylothorax]], [[chylopericardium]] and [[Ascites|chylous ascites]]
**[[Phrenic nerve|Phrenic nerve resection]] leading to diaphragmatic paralysis
**[[Phrenic nerve|Phrenic nerve resection]] leading to [[diaphragmatic paralysis]]
**[[Anemia]]
**[[Anemia]]
**[[Congestive heart failure|Congestive heart failure]] resulting from excessive blood flow
**[[Congestive heart failure|Congestive heart failure]] resulting from excessive [[blood flow]]
** Modified PTFE grafts can result in formation of [[seroma]] or shunt [[occlusion]] due to [[hyperplasia]] of [[neo-intima]]
** Modified PTFE [[grafts]] can result in the formation of [[seroma]] or [[shunt]] [[occlusion]] due to [[hyperplasia]] of [[neo-intima]]
**[[Stenosis]] of [[innominate artery]]
**[[Stenosis]] of [[innominate artery]]
**Sunt infection resulting in sepsis
**[[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.]]]
[[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.]]]
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==== Shunt failure ====
==== 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]].
* [[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:  
* [[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.
**[[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.
** [[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]].
**[[Heparin]] should be continued until there is a second [[dose]] of [[aspirin]].


==== Blockage of BT shunt ====
==== Blockage of BT shunt ====


* Blockage or shunt [[thrombosis]] is another surgical emergency with a reported incidence of 12%.
* [[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.
* 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.
* Operative management is usually required and the [[shunt]] is usually repaired or replaced if necessary.


=== High pulmonary blood flow ===
=== 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.
* 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.]]   
* [[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 =====
===== Causes =====


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


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


== Prognosis ==
== 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>
*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.
** 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.
** 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.
** 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.
** Post-shunt increase in [[Pulmonary artery|pulmonary arterial index]] (mm2/m2) is 158 +/- 21 versus 117 +/- 52 in classic Blalock-Taussig shunt.


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=== Central Shunt ===
=== Central Shunt ===


* Central shunt is made by creating an [[anastomosis]] between [[ascending aorta]] and main [[Pulmonary artery|pulmonary artery]].
* 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.  
* 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>
* 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.  
* [[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.
* It leads to adaptation of [[growth]], and flow, and it also reduces the risk for [[graft]] [[infection]].
{| class="wikitable"
{| class="wikitable"
|+
|+
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! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|-
|Can be done in small children with small vessels  
|Can be done in small [[children]] with small [[vessels]]
|Can not be performed in patients without [[patent ductus arteriosus]]
|Can not be performed in [[patients]] without [[patent ductus arteriosus]]
|-
|-
|Distortion of [[pulmonary vessels]] is avoided
|Distortion of [[pulmonary vessels]] is avoided
|Entry into [[pericardium]]
|Entry into [[pericardium]]
|-
|-
|Equal blood flow is provided to both lungs  
|Equal [[blood flow]] is provided to both [[lungs]]
|
|
|-
|-
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=== Potts shunt ===
=== Potts shunt ===
* Potts shunt can be used as an alternative to the classic BT 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.
* 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.
* 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>
* 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"
{| class="wikitable"
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! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|-
|[[Subclavian artery]] is used which has a large diameter hence, it is easy to perform surgery.
|[[Subclavian artery]] is used which has a large [[diameter]] hence, it is easy to perform [[surgery]].
|Increased incidence of [[pulmonary hypertension]]
|Increased [[incidence]] of [[pulmonary hypertension]]
|-
|-
|Lower chance of occlusion than CBTS and mBTS
|Lower chance of occlusion than CBTS and mBTS
|Increased blood flow to one lung while there is kinking of pulmonary artery
|Increased [[blood flow]] to one [[lung]] while there is kinking of [[pulmonary artery]]
|-
|-
|
|
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=== '''Waterston shunt''' ===
=== '''Waterston shunt''' ===
* It is made by connecting the [[ascending aorta]] and [[right pulmonary artery]].   
* 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.
* 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 ===
=== Cooley Shunt ===


* It is an [[Anastomosis|intrapericardial anastomosis]] between ascending aorta and the right pulmonary artery.   
* It is an [[Anastomosis|intrapericardial anastomosis]] between [[ascending aorta]] and the right [[pulmonary artery]].   
* Right anterolateral [[thoracotomy]] approach is used.  
* Right anterolateral [[thoracotomy]] approach is used.  
{| class="wikitable"
{| class="wikitable"
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! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
! style="background: #4479BA; width: 200px;" |{{fontcolor|#FFF|Disadvantages}}
|-
|-
|Use of right anterolateral incision for all approaches - [[Mediastinal|Mediastinal dissection]] is avoided
|Use of right anterolateral [[incision]] for all approaches - [[Mediastinal|Mediastinal dissection]] is avoided
|Improper size of shunt can lead to [[right heart failure]] and [[pulmonary congestion]]
|Improper size of the [[shunt]] can lead to [[right heart failure]] and [[pulmonary congestion]]
|-
|-
|Total repair can be done after this shunt in future  
|Total repair can be done after this [[shunt]] in future  
|Risk of intracardiac adhesions  
|Risk of [[intracardiac]] [[adhesions]]
|-
|-
|
|
|Complexity of the procedure  
|Complexity of the [[procedure]]
|}
|}


==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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