Coarctation of aorta

complete synopsis of disease with clinical features and treatment protocol

1. Coarctation Of Aorta DR DHEERAJ SHARMA RESIDENT (CTVS)

2. ORIGIN The word coarctation has been derived from latin word ‘COACTERE’, meaning to contract.

3. Anatomy of arch of aorta

4. Definition of hypoplasia * Proximal arch : 60% of ascending aorta * Distal arch : 50% of ascending aorta * Isthmus : 40% of ascending aorta

5. 1. Definition A congenital narrowing of upper descending thoracic aorta adjacent to the site of attachment of ductus arteriosus . 2. History Morgagni : 1st description in 1760 Bonnett : postductal & preductal type in 1903 Crafoord : 1st coarctation repair in 1944 Vorsschulte : prosthetic onlay graft or vertical incision and transverse closure in 1957 Waldhausen : subclavian patch aortoplasty in 1966

6. Robert gross: 1938 reported possible complication of severe haemorrhage and paraplegia after repair of CoA .

7. Surgical milestones

8. epidemiology Occurrence rate: 0.2-0.6/1000 live births Represents 5-8% of all congenital heart disease. 8 th most common congenital heart defect.

9. embryology Two theories The flow theory The ductal sling theory

10. The flow theory Any congenital anomaly that reduces the flow through left side heart and inturn through aortic isthmus in intrauterine life leads to poor development and ultimately coactation of aorta. Holds true for infantile or preductal type of coactation . Can explain occurrence of coactation with obstructive lesions of left side like aortic stenosis , bicuspid aortic valve, congenital mitral stenosis , VSD, shones complex. Also explain why the coarctation is not seen with right side obstructive lesions like TOF, PS, TA.

11. The ductal sling theory In patients with no associated intracardiac defects the flow theory does not explain the occurrence of CoA . For these patients the ductal sling theory holds good. SKODA more than 100 years ago postulated that it is the abnormal extension of contractile ductal tissue into the aorta which is responsible for pathogenesis of CoA . Resected specimen shows the extension of ductal tissue in circumferencial sling extending from ductus arteriosus and into the surrounding aorta. Contraction and fibrosis of this ductal tissue sling at the time of ductal closure would lead to formation of obstructing shelf with in the aorta .

12. The ductal sling

13. Types of coarctation Bonnet in 1903 divided the patients into 2 groups : infantile type and adult type. Later infantile type were known by name of preductal type and adult type was known by name of postductal type. The entity juxtaductal CoA is now a days used to denote adult type.

14. Preductal type (infantile)

15. Postductal (adult)

16. Diffences PREDUCTAL TYPE PDA is patent and large and provide blood flow to lower extremity. Tubular narrowing of isthmus No shelf like narrowing in aorta. Minimal post stenotic dilatation of aorta. Minor enlargement of intercostal arteries. POSTDUCTAL TYPE The ductus is closed and no longer acts as a shunt. No narrowing of isthmus. Shelf like narrowing with in the aorta in juxtaductal position. Post stenotic and prestenotic aorta is dilated. Intercostal arteries are grossly dilated.

17. Types

18. Preductal type(infantile)

19. Adult type CoA

20. Surgical classification of patients of CoA on basis of outcomes 3 groups Group I: patients with isolated CoA Group II : patients of CoA with VSD Group III: patients of CoA with complex intracardiac anomalies other than simple VSD.

21. Pseudocoarctation It is a rare condition presumably resulting from the congenital elongation of the aortic arch . The elongation leads to redundancy and kinking of the aorta which may appear similar to the coarctation but has no actual obstruction to the blood flow. There is no actual pressure gradient in pseudocoarctation . There is tendency of dilatation and aneurysm formation due to the turbulant flow in aorta.

22. Coarctation of abdominal aorta Occurs in 0.5 – 2% cases of coarctation . Etiology: congenital or related to other diseases like rubella, takayashu arteritis , von recklinghausen’s disease. Narrowing is diffuse in 1/3 rd cases and circumsccribed in 2/3 rd of cases. Diagnosis is angiography. Treatment is by patch aortoplasty or by bypass graft.

23. Associated pathology 1. Collateral circulation 2. Aneurysm formation of intercostal arteries * 3rd, & 4th rib notching * after 4 years of age 3. Coronary artery dilatation and tortuosity * due to LVH 4. Aortic valve * bicuspid (27-45%) * stenosis ( 6 - 7%) 5. Intracranial aneurysm * berry type intracranial aneurysm in some patients 6. Associated cardiac anomaly * 85% of neonates presenting COA

24. The collateral circulation More developed in adult or postductal type as ductus is closed and collaterals are the only source of blood supply to the lower half of body. There is progressive enlargement of collateral blood vessels around the coarctation segment. Collateral flow predominantly arisese from: Subclavian artery and its branches: Internal thoracic artery , intercostal artery, scapular artery, cervical artery, vertebral artery, spinal artery. Epigastric artery.

25. Collateral circulation

26. Natural history of CoA 1. Incidence * 5-8% of CHD (5 per 10000 live births) * Isolated CoA (82% of total CoA ) male:female = 2:1 CoA + VSD 11%, COA + other cardiac anomalies 7% * Complex CoA ; no sex difference 2. Survival of pure CoA * 15% : CHF in neonate or infancy * 85% : survive late childhood without operation * 65% : survive 3rd decade of life (2% at 60 years) 3. Bacterial endocarditis : common in 1 st 5 decades 4. Aortic rupture : 2~3rd decade 5. Intracranial lesion : subarachnoid hemorrhage(cong. Berry aneurysm)

27. Cause of death in CoA Congestive heart failure(26%) Bacterial endocarditis (25%) Spontaneous rupture of aorta (21%) Intracranial haemorrhage (13%)

28. Survival difference of CoA and general population

29. Pathophysiology Narrowed aorta produces increased left ventricular afterload and wall stress, left ventricular hypertrophy, and congestive heart failure. Systemic perfusion is dependent on the ductal flow and collateralization in severe coarctation

30. Presentation Bimodal distribution Group 1 : presents in first week of life Group 2 : presents in childhood and adolescent

31. Presentation in neonatal period They have ductal dependent circulation. Comes to light after closure of ductus with cardiovascular shock , renal failure and acidosis. They are a medical emergency. Due to less collateral flow in infancy ischemia of organs distal to coarctation occurs. At same time sudden increase in LV afterload leads to acute CHF. Management includes ventillation , sedation, correction of acid base balance, prevent hypothermia, prevent hypoglycemia, maintain optimum perfusion by inotropes and PGE1 infusion to keep ductus patent followed by surgical intervention when organ functions were optimised .

32. Presentation in childhood and adolescence. Majority of patients are asymptomatic and presents with hypertension on routine examination. Symptomatic patients may presents with : Headache and epistaxis due to systemic hypertension Claudication due to reduced blood flow to lower extremity Increased incidence of aneurysm of circle of willis leading to stroke Aortic aneurysm proximal or distal to coarctation Aortic dissection Atherosclerotic heart disease with MI Congestive heart failure. Bacterial endocarditis (fever).

33. Diagnosis Diagnosis in new born Diagnosis in children and adult

34. Diagnosis in newborn Newborn with severe CoA and ductus closure will present in shock , renal failure, acidosis. Physical examination: tachycardia, tachypnoea , pale appearance, lower extremity pulses absent, upper extremity pulses are thready . Child is hypotensive , liver enlarged CXR shows cardiomegaly and evidence of CHF. ECG shows left ventricular strain pattern 2 D echo shows lack of pulsatile flow in descending aorta, coarctation site and associated cardiac anomaly , anatomical details of arch.

35. Contd … Cardiac catheterization: not routinely done but can be done in patients with suspected complex congenital cardiac anomalies. CT angiography: in cases where cardiac cath is not necessary but imaging of arch is not adequate CT angiography is indicated to see anatomy of arch.

36. Diagnosis in older children Mostly asymptomatic Upper extremity hypertension with diminished femoral pulses. ECG: reveals LVH and LV strain pattern. CXR Shows: Rib notching(inferior border of 3-9 ribs) if patient is above 4 years of age due to erosion byenlarged collaterals. Classic 3 sign due to dilatation of LSCA , narrowing of coarctation site and dilatation of post stenotic segment. Cardiomegaly E sign on barium filled oesophagus

37. Contd …. 2 D echo: mostly diagnostic and shows all the necessary details, a shelf is seen posteriorly in coarctation segment. Cardiac catheterization study is required only if there are associated intracardiac anomalies, a question with regards to collaterals and when visualization by 2 D echo is poor. MRI is more beneficial in older children for anatomy of arch.

38. Difference in amplitude of upper and lower extremity pulse

39. Chest X ray

40. Chest X RAY

41. CT angiography

42. MR angiography

43. Surgical management Indications for operation 1. Reduction of luminal diameter greater than 50% at any age 2. Upper body hypertension over 150mmHg in young infant ( not in heart failure ) 3. CoA with congestive heart failure at any age

44. Techniques of operation General considerations Specific techniques Advantages and drawbacks of different techniques Complications and management.

45. General considerations Approach: Posterolateral thoracotomy through 3 rd or 4 th ICS. Median sternotomy approach is better in patients with associated cardiac anomalies that are to be repaired simultaneously. Arterial pressure monitoring lines are placed in right radial artery and femoral artery. In cases where rt subclavian artery arises below the coarctation segment then instead of radial line use temporal artery for proximal aortic pressure monitoring. Multiple chest collaterals are ligated and divided individually

46. Exposure

47. The lung is retracted anteriorly and mediastinal pleura overlying the coarctation segment is incised. The descending aorta , left subclavian artery , isthmus of aorta, ductus arteriosus and transverse aortic arch distal to left carotid artery is mobilised . ABOTT ARTERY: this artery is not found in normal subjects but is seen in CoA patients arising from posterior wall of aortic arch or lt subclavian artery. When encountered it should be ligated .

48. Abott artery

49. Management of aortic pressure during surgery Maintain proximal aortic pressure high during cross clamp to provide adequate arterial pressure distal to the clamp to prevent paraplegia. In adults 160-200 mm hg , in children 100-120mmhg The distal aortic pressure should not < 45mm hg

50. Steps to maintain distal aortic pressure If the distal aortic pressure falls below 45 mmhg , following steps are to be taken 1] use plasma expanders 2] use iontrops 3]relocate the clamp if possible 4]use of partial left heart CPB with left atrial & descending aortic cannulation 5] prevent acidosis 6] never use SNP

51. SURGICAL TECHNIQUES 1] resection & end to end anastomosis 2] prosthetic patch aortoplasty 3] prosthetic interpositio graft 4] resection with extended end to end anastomosis 5] subclavian flap aortoplasty 6] balloon dilatation angioplasty 7] bypass grafts

52. Resection & E TO E anastomosis Described by crafoord & nylin 1944 in adults Described by kerklin in 1955 in infant Narrowed coarctation segment is excised with direct end to end circumferential anastomosis of aorta Ductus is ligated & divided at the same time

53. D isadvantages High rate of recoarctation at surgical site[ 20-86%] particularly in the age of < 1 yr This technique does not address issue of hypoplastic transverse arch Not possible in older children as arch & descending aorta are more fixed & difficult to mobilise

54. Results

55. Causes of high recoarctation Use of silk suture instead of monofilament suture Inadequate resection of ductal tissue Lack of growth at circumferential suture line Lack of growth of hypoplastic transverse arch

56. Prosthetic patch aortoplasty Introduced by vosschulte in 1957 mainly for patients of 1-16 yrs. access is through left 4 th ICS Aorta is incised longitudinally in region of coarctation with prolongation of incision well above & below Patch extent upto left subclavian artery Is isthmus is also hypoplastic , the patch may be extended upto left carotid artery with clamp position proximal to left carotid artery

57. advantages The collateral vessels are preserved & do not require ligation & division Allows enlargement of isthmic hypoplasis Anastomosis is tension free The posterior aortic wall & even hypoplastic aortic arch grows after repair

58. D isadvantages Recoarctation [9%] Aneurysm formation of aortic wall opposite to patch

59. Results

60. Prosthetic interposition graft Described by robert gross in 1951using aortic homograft I960 , cooley & debakey used decron graft Indicated in patients > 10 yrs of age ,patients with associated aneurysm , patients with complex long segment coarctation & patients with recurrent coarctation .

61. D isadvantages Inability of prosthetic graft to grow with child Longer cross clamp time Increase incidence of bleeding

62. Subclavian flap aortoplasty Introduced by waldhausen & nahrwold in 1966 Indicated in infants Operation is perform through left 4 th ICS The aota is clamped proximal to left subclavian and dital to coactation Left subclavian is ligated distally near the origin of vertebral artery & divided The aorta is opened longitudinally & incision extended upto left subclavian The subclavian flap is folded onto the aorta

63. advantages Techniques is simple Short cross clamp time Avoidence of prosthetic matarial Easy hemostatic controll Increase anastomotic growth due to use of autologous flap

64. disadvantages Left arch ischemia due to ligation of left subclavian Poor growth & function of left upper limb Aneurysm formation Recoarctation [ 13%]

65. Results of flap aortoplasty

66. Resection with extended E TO E anastomosis Given by Amato in1966 Perform by left thoracotomy or median sternotomy Indicated in coarctation with hypoplastic distal transverse arch Adequate mobilzation of descending aorta, first two ot three intercostal vessels are ligated & divided, arched vessels are looped, clamp is placed between innominate & left carotid , ductal tissue excised, the coarctation segment is also excised & incision is made in transverse arch upto proximal clamp & the two segment of aorta anastomosed Mortality is 2% & recoarctation is 4%

67. advantages Low rate of recoarctation Avoidance of left arm ischemia & growth disorder It addresses & corrects hypoplasia of transverse arch Avoid prosthetic material Limits the potential for aneurysm formation Preseves normal vascular anatomy

68. Results

69. It is the currently procedure of choice for infants < 1 yr of age & in many children also.

70. Radically extended E TO E anastomosis Described by elliott Indicated in transverse arch hypoplasis Clamps are placed proximal to left carotid also involving some part of rihght innominate artery Allows extension of arch incision more proximal than extende E to E anastomosis

71. Balloon dilatation angioplasty Described by sos in 1979 In patients with neonatal coarctation Indications 1] patients with major systemic illness that increase the risk of surgery 2] older patients with mild discrete coarctation with poor collateral formation 3] for dilataion of recurrent coarctation

72. disadvantages Formation of aneurysm near dilatation site Residual gradient > 20 mm hg Aortic rupture with stents In stent stenosis particularly in younger & low birth weight children [31%]

73. complications

74. Paradoxical postoperative hypertension Two stage response First response is due to release of strech on baroreceptor on carotid bodies after removal of obstruction , it subsides within 24 hrs and it is due to increased sympathetic activities Second response is due to elevated level of renin angiotensin , it appears within 48-72 hrs of first response

75. Complication of hypertension on post operative period 1] mesenteric arterities & ischemia – child develop abdominal pain tenderness distension , GI bleeding requiring laprotomy Keep the patient NPO for 32-48 hrs

76. Treatment of postoperative hypertension In immediate postoperative period esmolol & nicardipine can be used to titrate B.P. ACE inhibitors can be used for second phase response Preoperative administration of propranolol is quite useful in blunting sympathetic response & managing postoperative hypertension

77. Persistence of postoperative hypertension There is a tendency of persistence of hypertension even after repair of coarctation which is proportionate to age of patient

78. paraplegia Described by hufnagel & gross in animals Bing described paraplegia in humans after coarctation repair in 1948 Incidence is 0.4%- 1.5% The incidence is correlated with length of cross clamp time [> 49 min] & presence of abberent origin of right subclavian below coarctation Management of aortic pressure is crucial SSEP are a possible method to assess reversible spinal cord ischemia

79. Aneurysm formation Both true & false aneurysms can form as a complication of coarctation repair Risk factor for aneurysm formation 1] patch aortoplasty at advance age 2] operation on recoarctation 3]use of decron as compare of PTFE patch

80. Recoarctation & reoperation Risk factor for recoarctation : 1] age < 2months 2] weight < 2 kg 3] residual ductal tissue 4] use of silk sutures for anastomosis

81. Definition of recoarctation Postoperative arm to leg peak systolic pressure gradient of > 20 mmhg acrossed repaired area Simultaneous arm & leg pressure measurement are best way to exclude posssibilty of residual obstruction Physical examination coupled with MRI angiography is most accurate.

82. Resection & E TO E anastomosis have high recoarctation rate { 19%} followed by flap aortoplasty {13%} Resection with extended E TO E anastomosis have lowest recoarctation rate{6%} Treatment is balloon dilatation , if not successful reoperation is considered, reoperation is difficult owing to dense scarring & adhesions.

83. Other procedures For patients with long segment coarctation , very dense adhesions or those requiring cardiac operations, jacobs & coworker suggested bypass graft from ascending to descending aorta through combined thoracotomy & median sternotomy approach Kenter also reports extra anatomic bypass grafts.

84. Bypass as described by Jacobs

85. Extra anatomy bypass

86. Special situation & controversies 1 . CoA proximal to left subclavian artery * 1% of all COA * reverse subclavian flap * abdominal CoA : 0.5 ~ 2% 2. Mild or moderate coarctation * degenerative change prone to occur 3. Prevention of paraplegia * Collateral circulation, hypothermia(< 45min at 33 deg C) * Descending aortic pressure under 50mmHg after clamp 4. Recurrent coarctation Increased mortality and morbidity 5. CoA with VSD or other anomalies Increased mortality and morbidity

87. conclusions Echocardiography is primary diagnostic tool CT & MR angiography is very useful specially to delineate the anatomy of transeverse arch Coarctation should be repaired at the time of diagnosis to prevent late hypertension

88. Resection & extended E TO E anastomosis is treatment of choice for infants , neonates & young children Interposition graft placement is indicated in older children & adults Balloon dilatation is initial procedure of choice for recoarctation if unsuccessful reoperation with patch aortoplasty or graft interposition is recommended.

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