COARCTATION OF AORTA

Dr. VIKAS

Deptt. Of ctvs, pgimer, chandigarh

COARCTATION OF AORTA

EMBRYOLOGY NOMENCLATURE PATHOPHYSIOLOGY NATURAL HISTORY CLINICAL FEATURES

NOMENCLATURE Coarctatus (Latin) – contracted tightened &

pressed together

Haemodynamically significant congenital narrowing of upper descending thoracic aorta adjacent to ductus arteriosus

Interrupted aortic arch - Lumen is atretic short distance seperates aortic ends .

Primary/ pure/ isolated CoA ± PDA without other associated anomalies

NOMENCLATURE (contd)

Hypoplasia of proximal transverse aortic arch is a diameter less than 60% of the ascending aorta

Hypoplasia of the distal aortic arch (between the left common carotid artery and the left subclavian artery) is a diameter < 50% of the ascending aorta.

Isthmic hypoplasia is diameter < 40% of the ascending aorta.

Hypoplasia of the distal arch requiring reconstruction is considered to be present if the diameter of the aortic arch (in mm) is less than 1 plus the infant’s weight in kgs.

History

1760 Johann Freidrich Meckel- extra ordinary dilatation of heart due to narrow aortic conduit.

1760 Morgagni- 1st description at autopsy

1790 Paris described pathologic features

Van Praagh –Juxtaductal (reflects different age of presentation of patients)

1928-1946 Reifenstein, Levine, Gross natural history (though did not appreciate that CoA is a frequent cause of death in infancy)

Abbot’s artery

Dr. Maude Elizabeth Seymour Abbott

first and largest post-mortem series in 1928

findings from all 200 previously documented cases over the age of 2 years, dating from the first report of aortic coarctation by Paris in 1791

Alfred Blalock

Alfred Blalock and Edward Park at Johns Hopkins, proposed the first surgical repair in 1944, describing a bypass from the left subclavian artery to the aorta to circumvent the area of narrowing.

Clarence Crafoord Crafoord and Nylin at

Karolinska Institute, (Stockholm, Sweden) performed the first resection with end-to-end reanastomosis in 1944.

19 October 1944, The patient was a 14 year-old boy. 32 years later, the patient was symptom-free with no pressure gradient across the repair

Robert Edward Gross

Gross (1948) used homografts to replace the narrowed segments of aorta.

Maurice Campbell

Natural history of coarctation of the aorta. Br Heart J 1970; 32:633–40

EMBRYOLOGY

Ductus tissue theory: skoda proposed abnormal extension of contractile

ductal tissue into aorta

contraction and fibrosis at ductal closure lead to aortic constriction and primary coarctation .

Haemodynamic theory: reduced flow across aortic isthmus during fetal life

lead to poor development of istmus “no flow no grow’

Turner syndrome XO: Fetal lymphatic obstruction distended thoracic duct compresses fetal descending thoracic aorta development of CoA

Gridlock mutant gene - related to early disturbance in vessel formation due to recessive mutant gene (Shelf in fetus with CoA)

CLASSIFICATION 1903 Bonnett classified into Adult(Post ductal) and

infantile(Preductal) Amato et al.

I - Primary CoA

II- CoA with isthmic hypoplasia III- CoA with tubular hypoplasia (isthmus and

segment between left common carotid artery & left subclavian arteries)

Subtypes 1. with VSD 2. with other major cardiac defects

Surgical classification:

I - Isolated CoA II - CoA with VSDIII - CoA with complex intra-cardiac anomaly

Types of coarctation

Morphological Features

Discrete CoA Adult / Juxtaductal/ Postductal In older chidren and adults Associated cardiac lesions are rare Well developed collateral circulation rare < 5 yrs of age. External - sharp indentation at CoA site Internal - obstructing diaphragm/ shelf 1. Infolding of Aortic media 2. Ridge formed by intimal hyperplasia 3. Present opposite to the site of ductus due to

reorientation of the angle formed by the ductus and the aorta

Changes Post stenotic dilatation Collateral formation Degenarative changes

Tubular hypoplasia Preductal/infantile Presents in infancy Associated with major cardiac anomalies collateral circulation/seconadary changes are

rare Externally continuity of PDA and DTA is seen

Coarctation of Aorta

COLLATERAL CIRCULATION

Seen mostly in isolated coarctation

Usually symmetrical on both sides

Inflow is from subclavian artery branches

Outflow into upper DTA

Mostly third and fourth intercoastals

Collateral formation in Coarctation of Aorta

Site Inflow Outflow

Lateral chest wall 1. 3rd to 6th ant. I/C art. from IMA (First two ant I/C art do not participate)

2. Lat. Thoracic art. From 2nd part of Axillary art

3. I/C br. from musculophrenic art.

1. Ant. Br of 3rd to 9th post. I/C art (First two post I/C art which arise from Sup I/C art, br of Costocervical trunk, do not participate)

2. Arteria Aberrans

Around the Scapula 1. Transverse cervical & transverse scapular art from thyrocervical trunk of subclavian art

2. Suprascapular art from Subclavian art3. Subscapular art from 3rd part of Axillary

art

1. Muscular br from post div of 3rd to 7th post I/C art

Diaphragm 1. Musculophrenic art from IMA 1. Inf phrenic art from Abd Aorta2. Lower post I/C art (ant div)

Upper abdominal wall 1. Sup epigastric art (terminal br of IMA) 1. Inf epigastric art (br of EIA)2. Ant div of upper lumbar art

Around the spinal cord 1. Ant spinal art from vertebral art2. Post spinal art from Post inf cerebellar

art or vertebral art

1. Radicular art from post div of post I/C and lumbar art

Arteria Aberrans

Branches from right side of descending thoracic aorta near the origin of right bronchial artery

Represents the remains of right dorsal aorta

Passes behind the trachea and oesophagus and may anastomose with the right Sup I/C art

Occassionally is enlarged to form 1st part of right Subclavian artery

Abbott’s artery

Arise anywhere on the posterior wall of aortic arch or back of the subclavian artery within a radius of 2cm from the origin of subclavian artery

Proceeds cranially and turns behind carotid artery and aortic arch

Represent evanescent remnant of fifth arch

Described By Maude Abbott

Rib notching seen in older patients

uncommon below 5 years

Seen in third to ninth rib posteriorly

Erosion of inferior surfaces of posterior ribs

Associated AnomaliesCardiac anomalies

1. PDA present in all cases of preductal or infantile type of CoA

2. PFO

3. Left sided obstructive lesions (aortic stenosis or atresia, bicuspid aortic valve (46%), subaortic stenosis, Shone’s syndrome)

4. Lesions with abnormal interventricular or great vessel communications (VSD either in isolation (11%) or in combination with transposition; and aortopulmonary window)

Coarctation of the Aorta with VSD

VSD in 40% present in the neonatal period :

increased L-R shunting (VSD) results in CCF.

no specific type

Coarctation of the Aorta with MV Abnormalities

seen in 25% 2% have severe abnormalities and 10%

of patients also have MR. Incidence of MS higher with VSD and

coarctation as compared with coarctation alone.

MS:parachute mitral valve or hypoplasia of the mitral valve ring or supravalvar ring.

Coarctation of the Aorta with AS

21% of patients with coarctation have aortic valve disease but only 2% are severe enough requiring surgery. 5% of all critically ill infants with coarctation also have aortic stenosis.

valvar or subvalvar

decreased cardiac output with poor pulses in all extremities masking upper and lower extremity pulse difference.

Coarctation of Aorta is NOT ASSOCIATED with TOF Congenital Pulmonary Stenosis Pulmonary Atresia Tricuspid Atresia Rt Aortic Arch

Associated Anomalies

Extracardiac vascular anomalies: Intracranial aneurysms variation in Brachiocephalic art anatomy left subclavian art arise at the site of stenosis Aberrant right subclavian art arise distal to

CoA (Subclavian steal syndrome due to reverse flow of vertebral art) or retroesophageal anomalous right subclavian artery

Dissecting aortic aneurysm Vascular rings—double aortic arch

Associated Syndromes

Turner’s syndrome

Von Recklinghausen’s disease

Noonan syndrome

Congenital rubella

Pathophysiology

1. Degree of obstruction

2. Type of Coarctation (preductal versus postductal)

3. Rapidity of development of obstruction

4. Status of ductus arteriosus

5. State of collateral development

6. Presence of associated intra-cardiac lesions.

Coarctation with IVS & closure of PDA

↑ ↑ SVR ↑ Asc Ao pr

PDA closure ↓ PBF

↓ Desc Ao Pr

↑ LV pr ↑LA Pr

↑L R shunt (ASD)

↓ LV vol load

Effect of Prostaglandin E1

Relaxes the ductus smooth muscle that has extended into the aortic wall

Maintains patency of ductus arteriosus

Effective within 7 – 10 days

Therefore it is required for pre-operative stabilization of patients with preductal coarctation who are duct dependent circulation

Effect of Oxygen

100% Oxygen

Early PDA closure

Increases Coarctation gradient

Coarctation with IVS & collateral formation

Collateral formation

Asc Ao requires less pr to maintain distal flow

↓ LV afterload

CCF improves

Coarctation with small VSD

Insignificant effect on infants ↑ LV pressure large shunt Leading to moderate PAH

Coarctation with large VSD

Large LR shunt when obstruction develops (↑ afterload)

If obstruction is acute ↓ CO, failure ↑ PA pressure very early pulm vascular

disease

Complications of longstanding CoA

Post-stenotic dilatation of upper descending thoracic aorta

Collateral formation which may become aneurysmal

Degenerative changes (saccular aneurysm formation, intimal erosion with dissection, marked disruption of elastic tissue and mycotic aneurysm)

Hypertension

Mycotic aneurysm and bacterial endocarditis in CoA

Dissecting aneurysm in complicating Coarctation of Aorta

ANEURYSM COLLATERALEnlarged tortuous third ,fourth intercoastals

Mostly saccular

Rare before 10 yrs

Prevelance 10% at end of second decade,20% by third decade

HT with CoA

Etiology Mechanical obstruction Reactivity of arteriolar resistance vessels ↓ compliance of Aortic wall Resetting of baroreceptor reflex plasma renin activity

Natural History

Incidence 50: 1lakh live births. Common in males.5-7% of congenital heart disease80% of these are isolated CoA ± PDANatural history of untreated isolated CoA 1st month:10% - acute CHF 1st year: 20% - CHF 1-4 yrs: 10% - chronic CHFThus 50% die within 10 yrs of life14-20yrs of age: 20% will die d/t Bacterial

endocarditis, aortic rupture or intracranial hemorrhage20-50 yrs of age: 20% d/t heart failure secondary to

HT or valvular heart disease

Natural History (Campbell 1970)

Studied survival of patients > 2yrs of age

20yrs of age: 25% will die

32yrs of age: 50% will die

46 yrs of age: 75% will die

58yrs of age: 90% will die

Hazard function

Very high peak of hazard during 1st month of life which falls rapidly, and by the end of 1year, it reaches constant hazard phase. That continues till 30 yrs of age, & then it starts rising

Natural History-Aortic rupture

Common in 2 & 3rd decade Involves usually ascending aorta leading to

haemopericardium with temponade Less often occurs at the site of post-stenotic

dilatation Are probably true dissecting aneurysm

Natural History- Coarctation with Intracranial lesions (Reifenstein, Abbott)

Death around 28-30 yrs Subarachnoid hemorrhage from rupture of

congenital berry aneurysm on the circle of willis arteries -cause of rupture may be associated HT,

CVA - atherosclerosis - emboli in the presence of infective

endocarditis

Natural History - CoA with VSD

Presentation is earlier than in patients with isolated VSD

Most of these babies die within few months without surgical treatment, in case the VSD does not diminish in size

Pseudo-coarctation Kinking of aorta in vicinity

of ductus Elongated tortuous, dilated

distal to Aortic arch and Prox. descending aorta

Absence of narrowing of Aortic lumen

Absence of gradient Abdominal CoA

In prox and distal to renal art

With renal artery stenosis

Clinical Presentation

Neonates & Infants– CCF as PDA closes– sudden CCF,shock,multi organ

failure,renal failure & necrotising enterocolitis,DeathChildhood—Usually asymtomatic,

HypertentionAdolescence & adult life--

--Asymtomatic--reduced femoral pulse

--murmur, hypertention--

headache,epitaxis,claudication --rarely with CCF, dissection,intracranial hemorrhage

--steal syndrome-during exercise

CLINICAL FEATURES

Newborn – no evidence of CoA CHF – early infancy(esp. at 1-2weeks) & 4th

decade CVA – 2nd – 3rd decade IE / Endarteritis – 2nd – 4th decade Rupture / Dissection – 3rd – 4th decade HT & CAD

CVS examination

Pulse – brachio-femoral delay left radial pulse weak – LSCA stenosis right radial pulse weak – aberrant

RSCA Subclavian steal syndrome Differential cyanosis (PDA with Right to Left shunt) Coarctation with VSD- no cyanosis as Left to

Right shunt

CVS examination

Blood pressure

Systolic blood pressure gradient

Difference b/w UL & LL BP > 20mmHg

On echo- gradient across CoA– 20mmHg

On cath withdrawl gradient > 20mmHg

The gradient will increase with exercise.

Hypertension

Auscultation

S1 loud mitral component S2 normal splitting with delayed loud A2 Gallop rhythm

Murmurs

Systolic 1. Collateral – delayed onset crescendo-

decrescendo in ant thorax, right infraclavicular, left sternal and suprasternal.

2. Coarctation – soft localized posteriorly3. Functional – ESM of BAV

Diagnostic methods

Two dimensional echocardiography can visualize coarctation in neonates and small infants and is usually the definitive study

Associated anomalies, severity

After infancy, helpful but usually not definitive

Diagnostic methods (ctd)

Cardiac catheterization and aortography

To confirm the diagnosis in older patients and in doubtful cases during infancy.

Define the anatomy, location and severity

Hypoplasia of arch Ductus Collaterals Associated lesions Pulmonary vasculature

Cardiac catheterization and aortography (ctd.) Resting gradient of >20 mm Hg is significant Falsely low gradient in:

1. Large ductus

2. well developed collaterals

3. low cardiac output/ poorly contracting LV

4. Multiple left sided obstructive lesions

Aortography

Decrease in luminal diameter approaching 50% significant.

Also reveal any hypoplasia of arch/isthmus Arrangement of aortic branches Degree of Collateral circulation aneurysm

Diagnostic methods (ctd)

CT/MRI increasingly being used in patients outside of infancy instead of cardiac catheterization

Also indicated if age > 20 years because of higher prevalence of aneurysm

Unequal arm pressures (anomalous right subclavian or involvement of left subclavian artery origin), absence of palpable collaterals and rib notching

( poorly developed collaterals)

Medical therapy

Optimization of hemodynamics before surgery with inotropic support and diuretic therapy.

Prostaglandin E1 - promotes ductal patency and improves perfusion of the descending aorta, renal and mesenteric beds.

Relaxation of the aortic end without actually opening the entire ductal lumen

Starting dose of 0.05mcg/kg/min increased to 0.1-0.15mcg/kg/min

May cause apnea or hypotension

Medical therapy (ctd.)

correction of the severe acidosis and oliguria, hypothermia, hypoglycemia and anemia.

If required intubation and mechanical ventilation.

If associated large VSD, keeping PCO2 to 45 to 50 mm Hg, thus raising the PVR and increasing the ductal flow to the lower body.

converting an otherwise emergent procedure into an elective one .

THANK YOU & to be contd