Jonas - Coarctation

Anatomy-

Simple Coarctation

-Preductal = Infantile Type

-Postductal = Adult Type

-Most are juxtaductal

-Neonate w Critical CoAo- sm muscle contraction --> both close PDA and CoAo just prox to the ductus

-pt will survive only if the CoAo isn't that severe, or there is rapid dvpmt of collaterals

-then over next few months, there is fibrosis of ligamentum arteriosum and a thick fibrous shelf forms within the Ao lumen. Externally it will look only mild, but there is still a thick shelf inside, opposite the ligamentum arteriosum

Associated Anomalies

-Bicuspid Aortic Valve

-about 1/2 of simple CoAo & IAA type B has bicupsid Ao vlv

-IAA Type B freq assoc w posterior malalignment of the conal septum--> subAS, but subAS much less common with CoAo.

-Ao Arch Hypoplasia

-no clear definition

-the prox Ao Arch should be >60% the diameter of the ascending aorta, and the distal Ao Arch >50% the asc Ao, and the Isthmus >40% the asc Ao.

-Z score <-2 is likely a good definition

-Prox Ao Arch = bn Innom & LCC - rarely hypoplastic enough in simple CoAo to need intervention

-Distal Ao Arch = bn LCC and LSCA - some have hypoplasia in simple CoAo setting

-Isthmus = bn LSCA and Lig Art/PDA - commonly hypoplastic with simple CoAo

-Bovine Trunk

- = innom art and LCC arise fr a single trunk

-Not uncommon type of arch hypoplasia

-The distal arch will arise directly off of the takeoff of the Innnom/LCC, and may be long and hypoplastic. If too long, may need to change surgical technique to deal with it...

-VSD

-about 30% of simple CoAo pts have VSD

(-of all CoAo, 30% in isolation, 30% simple CoAo + VSD, 40% Complex CoAo)

-others quote 48% VSD rate overall

-30% of pts had a VSD that was mod-large

-64% of the VSD's were conoventricular (outflow w musc extension), and were almost always large, about the size of the Ao annulus diameter. w some malalignment of conal septum postly, often w some Ao annulus hypoplasia

-may have tunnel like LVOT in infancy (rare), or subAS membrane (usually acquired)

-ASD & PDA

-PA rarely assoc w CoAo that presents beyond neonatal pd...

-stretched PFO/2nd ASD is assoc w sev CoAo, ?bc of hyoplasia or porly compliant L Heart (incr LAP...)

Complex Associated Heart Disease

-Taussig-Bing DORV & TGA with VSD

-w TGA VSD, the Ao is above a conus

-both can be assoc w anterior malalignment of conal septum --> VSD, and small Ao arch & jctl CoAo

-Malaligned Complete AVSD

-AVSD that overrides the RV more than the LV--> often under dvp of LV --> subAS if severe, w possible Ao Arch hypoplasia and CoAo

-Single Ventricle with Systemic Outflow Obstruction

-many forms, including HLHS, tri atresia with TGA, mitral atresia with Nl GAs and restrictive vSD, DILV w restrictive subAo conus. Many may have hypoplastic arch....

-HLHS

-at least 80% have CoAo

-freq severely underdvp arch, sometimes interrupted arch

Sx/Presentation

-Neonatal Critical Coarctation

-p/w shock as PDA closes bc no Q to lower body...

-Infantile Coarctation

-if PDA closed slowly, or collaterals dvpd, may present later w heart failure- incr RR and FTT

-no cyanosis

-Older child/Adult

-if mild-mod, can present late

-Sx- exercise intol, fatigue at lower extrem, but can e ASx if collaterals present

-+diff in 4ext bp...

...

Rx & Interventional Tx

-Neonatal Critical CoAo

-PGE, keep FiO2 at 21% to promote R to L shunting at PDA

-avoid enteral feeding to prevent NEC

-CHF beyond neonatal pd

-Lasix etc

-Balloon Angioplasty

-controversial for Tx of neonatal CoAo for initial repair bc less effective than surgery

-CoAo is the standard for recurrent CoAo

-for native coarctation:

-high risk of recurrence, thus doubtfully indicated even if pt has intraventric hemorrhage

-but in infants/older kids, ref 13-14- recurrence risk may be the same as surgery

-ref 15- even by cath may run risk of paraplegia

-it works by tearing the intima and media, but doesn't remove the ductal tissue...

-risk of aneurysms - 5% in one study

Surgical Indications & Timing

-Sx indications- if no resolution w Rx, then --> absolute indication

-if ASx in kids, can be controversial when to go

-Hypertension- might just show mild gradient (<20-30mmHg) if +collats

-if upper body BP is >2 standard deviations above Nl, and imaging shows diameter loss of 50% or more at the CoAo--> surgery

-BP gradient- >20-30mmHg--> absolute indication if 50% or more loss of CoAo diameter

-50% or more loss of CoAo diameter is an indication for surg

-Desc Ao Q- rarely helps in isolation, but is supportive

-Surgical Timing in ASx pt

-don't do in first 1-2 months bc there is still ongoing fibrosis to the arch/shelf, but no advantage to wait after pt is 2-3months old

-deferring surg beyond 5-10yo nearly always incr risk of essential htn in early adult life despite successful surgical repair w/o residual gradient

Surgery

Resection & End to End Anastomosis

-(preferred technique at Boston)

1) radial a-line at RIGHT side

2) pt in R lat decub position, approach via L 3rd or 4th IS thoracotomy, mainly posterior

3) retract L lung anteriorly

4) reflect the mediastinal pleural fr the area of the CoAo, and place stay sutures in ant edge of the pleura to retract them antly

5) ID the recurrent laryngeal nerve (!)

6) mobilize the prox vessels, staring w LSCA

-ID the large lymphatic vessels that often pass over the prox LSCA

7) mobilize behind the prox LSCA or adjacent distal Ao arch to avoid injury to Abbot's artery which often arises fr this area

8) mobilize the distal Ao to the level of the LCCA

9) dissect ligamentum arteriosum, making sure you preserve the LEFT recurrent laryngeal

10) dissect the medial prox desc Ao - doing it last bc injury to a collateral vessel here can --> bad bleeding

11) +/- place clamps, transect Ao and pursue the retracted bleeding collateral vessels- very fragile

12) mobilize desc Ao & prox vessels

13) ligate the lig arteriosum

14) place clamps at aorta- at distal Ao arch/LSCA

15) excise the coarctation, & fillet open the isthmus segment along the lesser curve, extending to distal arch (aka extended end to end anastomosis).

16) perform end to end anastomosis w continuous sutures, avoiding purse stringing

17) remove distal clamp, de-air, check for Q at lower extrem.

-may have a residual gradient initially, so wait 15-30 minutes and then there should be a P grad of <10mmHg unless there is arch hypoplasia. If there is simple CoAo, a residual gradient of up to 20mmHg is acceptable.

-if there is residual arch hypoplasia, one should be more aggressive in Tx it if there was also a L to R shunt (VSD).

Radically Entended End to End Anastomosis

-for pts w hypoplastic Ao arch

-dissect along prox Ao arch up to the distal Asc Ao...

-extend the aortotomy across the entire surface of the arch into the distal asc Ao,

-bc the head and neck vessels are mobilized, one can bring the desc Ao up to the Asc Ao...

Left Subclavian Patch Aortoplasty

-mobilize LSCA to level of 1st rib

-ligate the L verebral artery to prevent LSCA steal phenomenon

-ligate the LSCA distally

-ligate the PDA/LA, and clamp across distal Ao Arch and prox desc Ao

-divide the LSCA proximal , open it longitudinally w incision carried along the isthmus of Ao, and turn it down as a flap

-suture the flap to the most distal extent of the desc aortotomy

Reverse LSCA Patch Aortoplasty

-best for hypoplasa of the distal arch

-usually performed with CoAo resection & end to end anastomosis

-mobilize the LSCA as for antegrade SCA flap...

-dissect the Ao arch to pt of prox LCCA and dissect prox LCCA

-clamp prox Ao arch and distal LCCA

-clamp at isthmus, allowing fwd Q thru PDA to desc Ao

-ligate distal LSCA & transect it

-open LSCA longitudinally at rightward aspect, and extend incision across the superor surface of distal arch, then distallly along the LCCA opposite the LSCA

-turn the flap back retrograde twd the LCCA w the toe sutured into the comm carotid incision

-body of the LSCA patch is sutured across the incision in the distal Ao arch

-then resect the CoAo and do end to end anast

...

...

Synthetic Patch Aortoplasty

-risk of late aneurysm is high

-but may be worthwhile if very long tubular narrowing of Ao...

-longitudinal incision is made on ant and L ward face of A, across the CoAo

-patch w Gortex or Dacron

One Stage Repair of VSD & CoAo

-much controversy as to the best approach

-if it might close on its own, c/s L thorocotomy w CoAo repair and PA band

-then can return later to close the VSD if needed. May avoid CPB need, but need extended hospitalization need 2 surgeries, etc

Median Sternotomy for One Stage Repair of VSD & CoAo

-cannulate the Asc Ao into R side of the mid Asc Ao; venous cannulation

-Right after you connect to CPB, must ligate the PDA

-Deep hypothermia

-mobilize arch vessels

-ensure you preserve the L recurrent larngeal and vagus nerve, and phrenic nerve

-excise coarc and do end/end anast +/- radical extension or patch plasty (which would need circ arrest- max 15 minutes!)

-then reperfuse after circ arrest, and then circu arrest again for VSD closure (max 20 minutes more)

CoAo Surgical Complications

Early:

-Paraplegia

-0.5% incidence in large 1972 study

-currently much lower risk- maybe bc we do it younger so less likely to have major hemorrhage 2y to injury of fragile collateral vessels. Also, shorter surture line in young pts so quicker cross clamp time.

-it is likely that extended cross clamp time (>30min) and hypotension are r/f

-the anterior spinal artery is supplied by branches fr R and L vertebrals, which arise fr subclavian arts

-aberrant RSCA increases risk of decr Q to ant spinal artery

-if the spinal art is discontinuous, incr risk of spinal ischemia

-incr if multiple intercostals are occluded

-hypothermia helps

-incr risk w hypotension

-Hemorrhage

-bc of tearing of sutures bc of excessive tension, thus they use running sutures

-Chylothorax

-lymphatic vessels crossing the LSCA is at risk

-L recurrent laryngeal nerve palsy

-visualize it when mobilizing the lig arteriosum; avoid excessive tension of the pleural flap...

-Paradoxical Hypertension

-common to have incr BP in first days/weeks postop. Initially bc of elevated catechols bc of stress in setting of hyperactive vasculature..., and later on bc incr angiotensin levels until the hormonal hypertension resolves over several weeks

Late:

-Hypertension-early onset essential htn common if unrepaired til 5-10yo, but must r/o recurrent CoAo

-Recurrent CoAo- would need balloon angioplasty

-Aneurysm formation

-late risk, espec post synthetic patch aortoplasty

-higher risk if surg was in older pt

-also a risk of balloon angiiplasty

Surgical Results

-overall survival (included pts w small L heart...) - 84% 2yr survival w mainly end/end anast

-mortality increased if pt had prox arch repair

-diff study- freedom fr reintervention at 5yrs was 93%...

Long Term Follow Up

-long term survival in pts discharged fr hospital was 95% vs 97% in general population

-incr mortality and htn w late repair

-Aneurysm formation

-incr w older age & patch plasty

-Arch Hypoplasia & CoAo outcome

-freedom fr recoarc- 57% at 4yrs p SCA plasty, 77% p end/end, 83% after extended end/end, 96% after radical end/end anast

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