Coarctation of Aorta by Dr Kuntal Surana

Coarctation of Aorta PPT

1. COARCTATION OF AORTA DR KUNTAL SURANA LTMMG AND HOSPITAL

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

3. ANATOMY OF ARCH OF AORTA

4. Introduction Narrowing of the thoracic aorta beyond the level of the innominate artery (discrete coarctation of the aorta or transverse arch hypoplasia ) is broadly known as Coarctation of Aorta.

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

6. EPIDEMIOLOGY Represents 4% to 8% of cases of congenital heart disease, with an incidence in the general population estimated at 0.2 per 1000 live births. Bicuspid aortic valve is an associated finding in up to 50% of patients, and hypoplasia of left heart structures is relatively common. A ventricular septal defect (VSD) may be seen in 30 to 60% of patients. 8th most common congenital heart defect.

7. EMBRYOLOGY Two theories 1. The flow theory 2. The ductal sling theory

8. 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 coarctation of aorta. Holds true for infantile or preductal type of coarctation . Can explain occurrence of coarctation 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.

9. 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 .

10. THE DUCTAL SLING

11. TYPES OF CoA 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.

12. PREDUCTAL TYPE

13. POSTDUCTAL TYPE

14. DIFFERENCES PREDUCTAL 1. PDA is patent and large and provide blood flow to lower extremity. 2. Tubular narrowing of isthmus 3. No shelf like narrowing in aorta. 4. Minimal post stenotic dilatation of aorta. 5. Minor enlargement of intercostal arteries. POSTDUCTAL 1. The ductus is closed and no longer acts as a shunt. 2. No narrowing of isthmus. 3. Shelf like narrowing within the aorta in juxtaductal position. 4. Post stenotic and prestenotic aorta is dilated. 5. Intercostal arteries are grossly dilated.

15. SURGICAL CLASSIFICATION ON THE BASIS OF OUTCOME 1. Group I: patients with isolated CoA 2. Group II : patients of CoA with VSD 3. Group III: patients of CoA with complex intracardiac anomalies other than simple VSD.

16. 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.

17. 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 1/3rd cases and circumsccribed in 2/3 rd of cases. Diagnosis is angiography. Treatment is by patch aortoplasty or by bypass graft.

18. 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: 1. Subclavian artery and its branches: Internal thoracic artery , intercostal artery, scapular artery, cervical artery, vertebral artery, spinal artery. 2. Epigastric artery.

19. NATURAL HISTORY If the coarctation is left untreated, the prognosis varies from severe heart failure in infancy to asymptomatic hypertension in older children and adults. Collateral vessels become prominent because of increased flow within the intercostal , internal mammary, and scapular blood vessels. The increased flow within these vessels can be sufficient to reduce the blood pressure gradient between the upper and lower extremities at rest. Untreated coarctation is associated with a substantially diminished long-term survival, with 75% mortality by 50 years of age. Death in these patients is usually due to systemic effects of hypertension, including heart failure, intracranial hemorrhage, coronary artery disease, or aortic rupture or dissection.

20. CAUSE OF DEATH Congestive heart failure(26%) Bacterial endocarditis (25%) Spontaneous rupture of aorta (21%) Intracranial haemorrhage (13%)

21. PATHOPHISIOLOGY 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 .

22. 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 .

23. PRESENTATION IN CHILDHOOD AND ADOLESCENCE Majority of patients are asymptomatic and presents with hypertension on routine examination. Symptomatic patients may presents with : 1. Headache and epistaxis due to systemic hypertension 2. Claudication due to reduced blood flow to lower extremity 3. Increased incidence of aneurysm of circle of willis leading to stroke 4. Aortic aneurysm proximal or distal to coarctation 5. Aortic dissection 6. Atherosclerotic heart disease with MI 7. Congestive heart failure. 8. Bacterial endocarditis (fever).

24. 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. 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.

25. DIAGNOSIS IN OLDER CHILDREN Mostly asymptomatic Upper extremity hypertension with diminished femoral pulses. ECG: reveals LVH and LV strain pattern. CXR Shows: 1. Rib notching(inferior border of 3-9 ribs) if patient is above 4 years of age due to erosion byenlarged collaterals. 2. Classic 3 sign due to dilatation of LSCA , narrowing of coarctation site and dilatation of post stenotic segment. 3. Cardiomegaly 4. E sign on barium filled oesophagus 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.

26. CHEST X-RAY

27. CHEST X-RAY

28. CT ANGIOGRAPHY

29. MR ANGIOGRAPHY

30. 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

31. GENERAL CONSIDERATIONS Approach: 1. Posterolateral thoracotomy through 3rd or 4th ICS. 2. 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

32. 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 left subclavian artery. When encountered it should be ligated .

33. 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

34. 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

35. SURGICAL TECHNIQUE 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

36. RESECTION AND END TO END ANAST0MOSIS 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

37. DISADVANTAGES 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

38. 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

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

40. 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

41. DISADVANTAGES Recoarctation [9%] Aneurysm formation of aortic wall opposite to patch

42. 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 .

43. DISADVANTAGES Inability of prosthetic graft to grow with child Longer cross clamp time Increase incidence of bleeding

44. SUBCLAVIAN FLAP AORTOPLASTY Introduced by waldhausen & nahrwold in 1966 Indicated in infants Operation is perform through left 4th ICS The aorta is clamped proximal to left subclavian and distal to coarctation 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

45. ADVANTAGES Techniques is simple Short cross clamp time Avoidence of prosthetic material Easy hemostatic control Increase anastomotic growth due to use of autologous flap

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

47. RESECTION WITH EXTENDED END TO END 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 or 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 segments of aorta anastomosed Mortality is 2% & recoarctation is 4%

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

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

50. RADICALLY EXTENDED END TO END ANASTOMOSIS Described by elliott Indicated in transverse arch hypoplasis Clamps are placed proximal to left carotid also involving some part of right innominate artery Allows extension of arch incision more proximal than extende E to E anastomosis

51. 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 dilatation of recurrent coarctation

52. 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%]

53. COMPLICATIONS OF SURGERY RECOARCTATION PARADOXICAL HYPERTENSION PARAPLEGIA RLN INJURY LEFT ARM ISCHEMIA HEMORRHAGE ANEURYSM FORMATION CHYLOTHORAX HORNER’S SYNDROME PHRENIC NERVE INJURY CEREBROVASCULAR ACCIDENT

54. PARADOXICAL POSTOPERATIVE HYPERTENSION Two stage response First response is due to release of stretch 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

55. COMPLICATION OF HYPERTENSION ON POSTOPERATIVE PERIOD 1] mesenteric arterities & ischemia – child develop abdominal pain tenderness distension, GI bleeding requiring laparotomy Keep the patient NPO for 32-48 hrs

56. 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.

57. PERSISTENCE OF POSTOPERATIVE HYPERTENSION There is a tendency of persistence of hypertension even after repair of coarctation which is proportionate to age of patient.

58. PARAPLEGIA Described by H ufnagel & 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 is a possible method to assess reversible spinal cord ischemia

59. 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

60. RECOARCTATION AND REOPERATION Risk factor for recoarctation : 1] age < 2months 2 ] weight < 2 kg 3] residual ductal tissue 4] use of silk sutures for anastomosis

61. DEFINITION OF RECOARCTATION Postoperative arm to leg peak systolic pressure gradient of > 20 mmhg across 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 . 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.

62. 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.

63. BYPASS AS DESCRIBED BY JACOBS

64. EXTRA ANATOMICAL BYPASS

65. SPECIAL SITUATIONS AND 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

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