Aortic arch anomalies

Dr.Deepak Raju

Embryology

• Heart is first seen in the form of two endothelial heart tubes-18th day of foetal life

• Fusion results in a single tube with a series of dilatations(sinus venosus ,atrium ,ventricle &bulbus cordis) and begins to beat by 22nd day

• Bulbus cordis represents arterial end of the tube-prox part conus,distal truncus arteriosus

• First arteries to appear are right and left primitive aorta connected to the endothelial heart tubes

• Portion lying ventral to foregut(ventral aorta)-connected to first pharyngeal arch-to the portion dorsal to foregut(dorsal aorta)

• After the fusion of endocardial heart tubes,ventral aorta fuse to form aortic sac

• Truncus continues with the aortic sac from which right and left pharyngeal arch arteries arises

• They arch backward on lateral side of foregut –continues as right and left dorsal aorta-fuse to form descending aorta

• During 4th and 5th week,successive arterial arches appear in 2nd to 6th pharyngeal arches

• Each connects ventrally to aortic sac&dorsally to dorsal aorta

• Greater part of 1st &2nd arch arteries disappear.1st arch remnant-maxillary artery,2nd arch remnant –hyoid and stapedial artery

• 5th arch artery regress completely• 3rd and 4th open to ventral part of aortic sac.6th to dorsal

part.• Spiral septum formed in truncus in the 5th week extends to

aortic sac.blood from pul.artery goes to 6th arch artery,from aorta to 3rd &4th arch arteries.

• Dorsal aorta gives lateral intersegmental branches to body wall.7th cervical intersegmental supplies upper limb bud.

• Portion of dorsal aorta b/w 3rd and 4th (ductus caroticus)disappear

• Each 6th arch artery connects to the pulmonary vascular tree.portion b/w this connection and dorsal aorta-ductus arteriosus-regresses on right side

• 3rd-common carotid and prox.int.carotid• 4th –

– Lt.-aortic arch b/w LCCA and LSCA.– Rt-prox RSCA

• 6TH –– prox part –prox pul art– distal part-ductus on left and right side involutes

• Lt dorsal aorta-aortic arch distal to LSCA• Rt dorsal aorta-

– cranial portion-RSCA distal to 4th arch.– distal portion-involutes

Edward s double aortic arch model

• Anomalies of aortic arch to be conceptualised as variations in regression of different segments from the hypothetical double arch

Totipotential aortic arch diagram

History

Anomalous RSCA-Hunauld,1735Double aortic arch-Hommel 1737Right aortic arch –Fioratti,Aglieti-1763Interrupted aortic arch-Steidele-1788Bayford,1787-dysphagia by vasc ring-coined

term dysphagia lusoriaGross,1945-first division of a vasc ring

Sidedness of the arch

• Left and right arch refers to which bronchus is crossed by the arch

• Echo or angio-branching pattern of brachiocephalic vessels

• First arch vessel that contains carotid artery opposite side of arch

• Retroesophageal or isolated vessels-opp to side of arch

• MRI and CT-conclusive

Anatomical classification

• Abnormalities of branching• Abnormalites of arch position-cervical

arch,right arch• Supernumary arches-double aortic arch and

persistent 5th arch• IAA• Anomalous origin of pulmonary artery branch

Clinical classification

• Vascular rings• Non-ring vasc.compression• Non-compressive arch malformations• Ductal dependent arch anomalies

vascular ring-aortic arch anomaly in which trachea and esophagus surrounded by vasc. structures

Double aortic arch most common(40%),rt.aortic arch with lt.ligamentum(30%),aberrant RSCA(20%),anomalous innominate(10%).

• Symptoms-– Stridor,Pneumonia,bronchitis– Reflex apnoea or choking on eating– Hyperextension of neck– Increased resp distress a/w intercurrent

resp.infections– swallowing difficulty

• 3 d΄s opposite to side of arch-diverticulum,dimple,descending aorta

• Diverticulum –large vessel from desc.aorta giving rise to a smaller calibre vessel with a sudden taper

• Dimple –tapered blindly ending outpouching• Descending aorta in upper thorax opp.to side

of arch-connected by ligamentum arteriosum

Normal left arch development

Variants of left aortic arch

• Common brachiocephalic trunk– Right innominate and left carotid from single

origin– 10% of normal – Compression of trachea possible

• Separate origin of left vertebral artery– 10%– Prox to LSCA– 3rd arch vessel smaller than 4th

Lt arch with retroesophageal RSCA

• 0.5% incidence• m.c.arch anomaly• 38% of down s′• Disappearance of Rt 4th arch-distal Rt dorsal aorta

becomes prox RSCA• Rt 6th arch disappear• Usually asymtomatic• Barium –smaller filling defect on postr aspect of

esophagus slanting upward• Angio-earlier filling of Rt carotid on aortic root injection

Lt ao.arch and retroesophageal diverticulum of Kommerell

• First vasc ring to be diagnosed during life• Similar to previous except for persistent 6th

arch-ligamentum which completes a vasc . Ring

• Prox.RSCA dilated to form diverticulum

Lt ao.arch,rt.desc aorta,rt.ductus(circumflex aortic arch)

• Branching pattern similar to earlier-arch retroesophageal,RSCA the last arch vessel is not retroesophageal

• Desc.aorta connected to RPA by ligamentum-forms vasc.ring

Lt ao arch &isolated RSCA

• Right 6th arch persists• RSCA from rt ductus• RSCA and vertebral fills from PA in foetal life• When ductus closes-retrogradely from circle

of willis– Vertebrobasilar insufficiency– Congenital subclavian steal– Absent rt arm pulse

Lt ao arch with cervical origin of Rt subclavian

• Marker of 22q11 deletion• Innominate trifurcates in the neck-RSCA

travels back to thorax• Subclavian origin from 3rd arch

Right aortic arch

• A single aortic arch that crosses rt mainstem bronchus

• 13-34% in TOF• 30-40% in truncus arteriosus• 20% in pul.atresia with VSD• 7.7% in tricuspid atresia• 8-10% in transposition

Right aortic arch-mirror image type

• Sequence of arch vessels-lt.innominate,rt carotid,RSCA

• Ligamentum lt sided• No vasc ring.can form rarely if Lt. ductus from

rt desc aorta• CCHD in 98%(48% TOF)

Rt ao arch with retroesophageal diverticulum of Kommerell

• Sequence –lt carotid,rt carotid ,RSCA,a large retroesophageal vessel( diverticulum) from which LSCA arises

• Lt ligamentum completes the ring• Disappearance of Lt 4th arch and persistence of

6th arch

Rt arch with retroesophageal LSCA

• Similar to previous one except for the absence of retroesophageal diverticulum

• Ductus is rt sided• No vasc ring• Involution of lt 4th and 6th

Rt arch with Lt desc aorta and Lt ligamentum

• Aortic arch itself crosses midline-connects to lt ductus to form vasc ring

Cervical aortic arch

• Arch found above level of clavicle• Two categories-normal branching pattern or

anomalous subclavian artery and vascular ring• 2nd group-devided acc.to carotid origin(bicarotid

trunk or separate origin of ext.&int carotid)• Mechanism-– Failure of normal descent of aortic arch system– Persistence of ductus caroticus&involution of 4th arch-3rd

arch becomes definitive aortic arch with separate origin of ext &int carotid from it

Double aortic arch

• Both rt and lt arches present• Persistence of both rt and lt 4th arch which join TA sac to

dorsal aorta both of which persist• Only one 6th remain• Rarely a/w other CHD, when present-TOF most common• Both arches can be patent or one hypoplastic or

atretic(usu.left)• Form complete vasc.rings• Symmetric origin of 4 arch vessels from respective

arches when both patent

Persistent 5th arch

• First reported by Van praagh in 1969• Double lumen aortic arch in which both arches

appear on same side of trachea• 2 common sub categories-– Subway vessel beneath normal arch(4th arch)that

extend from innominate to take off of LSCA– Double lumen aortic arch with atresia of superior

arch with patent inferior arch-common origin of all brachiocephalic vessels from asc.aorta

Interrupted aortic arch

• Defined as complete separation of ascending and descending aorta

• Celoria and Patton classification(1959)– Type A-interruption distal to SCA that is ipsilateral

to 2nd carotid artery– Type B-interruption b/w 2nd carotid and ipsilateral

subclavian– Type C-interruption b/w carotids

• Each of the types subcategorised to 3 types– 1.without retroesophageal or isolated subclavian artery– 2.with retroesophageal subclavian artery– 3. with isolated subclavian artery

• Interrupted rt arch seen only in DiGeorge syn.• Type A-aorticopulmonary septal defect,TGA• Type B-m.c,a/w conotruncal anomaly,DiGeorge

syn.• Type C-rare

• Type A-involution of both dorsal aorta distal to 4th arch,prox to persistent 6th arch

• Type b-involution of one 4th arch and one dorsal aorta b/w 4th and 6th

• Type C-involution of one limb of truncoaortic sac

• Present with acute cardiovasc collapse after closure of ductus

• Absence of all limb pulse with strong carotid pulse suggest type B with anomalous subclavian

Anomalous origin of pulmonary artery from ascending aorta

• Anomalous pulmonary artery branch arising from ascending aorta in presence of a MPA arising separately

• Anomalous RPA-– More common– Embryonic branch pul.artery joins rt side of TA sac,but fails to

join MPA before septation– High incidence of aorticopulmonary septal defect

• Anomalous LPA– a/w TOF in 74%– Embryonic branch pul.artery fails to join TA sac

• CCF in infancy f/b early devt of pulmonary vascular disease

Anomalous origin of LPA from RPA

• LPA arises from RPA and passes b/w trachea and esophagus-pulmonary artery sling

• Tracheal compression-severe resp distress and stridor

• Isolated anomaly,rarely a/w TOF• LPA passes beyond trachea before joining TA

sac• Anterior indentation on barium swallow

Summary

• Aortic arch anomalies and vascular rings can be interpreted on the basis of embryology

• With the devt. Of MRI and CT 3-D reconstruction is possible

• Intervention required only when symptomatic or when a/w other cardiac anomalies

• Thank you