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AVSD Mavroudis18
AVSD Mavroudis18
History
-1958- first successful repair, by Lillehei, via cross-circulation, --> direct suture of atrial rim to IVS crest
-initially, had high mortality, and high morbidity- complete HB, residual AV regurg, subAo stenosis
-outcome improved w subsequent understanding of the anatomy etc
-1958- Lev located His bundle in pts w AV canal--> less HB
-1962- Maloney & Gerbode described a single-patch technique, suspending the AV vlv tissue to a single patch that closes both defects.
-1966- Rastelli classified complete AVC types
-1975- Trusler first reports a 2 patch teqhnique- Dacron patch close to VSD part, suture the vlv leaflets to the crest of the patch, closed the MV cleft, and use a pericardial patch to close the ASD
-___-Nunn rec repair without a patch for the VSD
-each of the diff approaches might still be needed today...
-Initially, patients would get a PA Band to prevent CHF early on, but no longer used generally as we can do a complete repair sooner.
-PA band often caused incr AV regurg, so didn't help the CHF (Ref11)
-currently most centers rec repair at 3-6mo
Pathology
Partial AVSD = Ostium primum defect (crescent defect at inf atrial septum) + Cleft anterior leaflet of the left sided AV vlv (--> AV regurg)
-Nearly always, the AVR is via the cleft in the L AV vlv
Complete AVSD = Ostium primum defect + inlet VSD
-a common AV vlv bridges both sides of the heart, w a superior (anterior) and inferior (posterior) bridging leaflet
Intermediate AVSD =two distinct L and R AV vlv orifices + ostium primum defect + inlet VSD
-'unlike CAVC, there is no "bare area" at the ventric septum'
-Mavroudis uses "Transitional" and "Intermediate" AVSD interchangeably
-Rastelli Classification
-DDx by anterior (sup) bridging leaflet morph (amt of bridging and cord attchmt)
-A- it is split into to 2 halves at the septum, with the L sup leaflet entirely over LV and R at RV...
-due to extensive attchmt of the sup bridging leaflet to the crest of the IVS by cords
--> divides the ant common AV vlv into a TV and MV component for surgeons...
-B- (rare) anomalous pap muscle attchmt fr the R side of the ventric septum to the L side of the common ant bridging leaflet
-C- marked bridging by the ant bridging leaflet over the IVS, into the RV
-it is not divided, and floats freely over the IVS, without cord attchmt to the crest of the IVS
-Mavroudis series- (n=110), 69% A, 9% B, 22% C
-CAVC is assoc w other conotruncal xx, espec TOF, DORV, TGA
-6% have TOF (Ref 16) - less likely to have CHF Sx bc of decr Qp; cyanosis d/o amt of PS
-6% have DORV
-3% have TGA
-10% have PDA
-3% have LSVC
-1% have LVOTO fr discrete subAS or redundant AV vlv tissue (pre-op)
-Conduction system is usually displaced (Ref 17)
-AV nd more post and inf, near the CS ostium
-His bundle runs along the inf rim of the VSD, so the bundle branches start more inf than Nl
--> NW axis on ECG
Hemodynamics & NHx
-Incr Qp fr L-->R at ASD & VSD
-if no VSD, then hemodynamics are like a big ASD, w incr RV stroke volume
-AV vlv regurg increases at the cleft L AV vlv increases w time --> large L-->R shunt
--> progressive cardiomegaly and CHF Sx, much worse than a pt w an ASD without AV regurg
-PAP = Systemic P bc of the large L-->R shunt --> phtn fr birth that is unrelenting until they get a PAB or a complete repair
-Rapidly progress to pulm vasc dz (Ref 18)
-Down's synd may incr speed at which they get phtn (Ref 19)
-PVR can incr signif by a few months old
-PVR 0-3mo was 2, by 4-6mo it was 4, and by 7-17mo it was 5u/m2
-AV regurg + phtn and CHF makes things all the more worse w more vol OD to ventricles--> sooner progression of pulm vasc obst dz.
Dx
-CHF Sx since infancy usually
-freq URI, poor PO, FTT, diaphoresis w feeds, tachy, DOE, hepatomegaly, tachypnea
-hyperactive precordium
-loud systolic murmur if signif AV regurg
-CXR- CM and biventric enlargement w incr pulm vasc markings
-ECG- BVH, long PR, NW axis
-Echo-
-check valvar abNlies
-check assoc xx- LSVC, PDA, LVOTO
-check amt of AVR
-Cath-
-less used bc most pts have systemic PAP, so only useful for those that present late to check if PVR is so high that repair isn't indicated any longer
Timing of Operation
-Partial AVSD -best to do electively bn 2-4 years old (Ref 22-23)
-if signif L AV regurg, or hypoplastic L side structures (CoAo, abNl MV, SubAS) then c/s earlier
-Complete AVSD -best to do it bn 3-6 months old (Ref 15, 25)
-waiting to 1 yr --> irreversible incr in PVR
-Intermediate AVSD - d/o amt of shunting, do learger VSDs earlier
-if assoc w TOF or signif RVOT stenosis, then can palliate w a BT shunt first (Ref 26-28)
Operative Management
-Goals:
-close the ASD
-close the VSD
-create two competent AV vlvs
-avoid AV nd/His bundle damage
-CPB w moderate hypothermia to 28C and intermittent cold blood cardioplegia for myocardial protection (Ref 15)
-long, medial atriotomy, parallel to RCA, extending to a pt medial to the IVC
--> great exposure for repair
-Some use both antegrade and retrograde cardioplegia (Ref 30)
-TEE to assess the AVC (Ref 31)
-Inspect intracardiac anatomy
-check RV and LV size, ASD & VSD size and shape, number and location of pap muscles, cord arrangement and attchmt to IVS
-float the AV vlvs to their closed position by filling ventricles w saline --> assess the line of apposition bn the ant and post common leaflets, and ID the line that divides the vlvs into the R and L parts.
-If TOF, then the patch must be wider near the subAo area to allow enough redundancy at the ant-sup end of the VSD to avoid LVOTO, so it is a comma shaped VSD patch.
Single-Patch Technique
-PTFE or Dacron patch or pericardial patch (though latter risks aneurysm dvp at VSD- Ref 32)
-Dacron patch has some risk of postop hemolysis if a jet of AV vlv insuffic strikes it
-PTFE is less malliable
1) float the AV vlv leaflets to their closed position
2) find line of apposition of ant and post common leaflets, and draw imaginary line demarcating the L and R AV vlvs, by the copatation of the ant and post common leaflets w a horizontal mattress suture
3) suture the crest of the IVS to inf aspect of the patch w interrupted horiz mattress sutures, weaving the patch around the cords if needed
4) Anchor the R AV vlv components to the patch (ideally w the same sutures as step 3
5) close the ASD by suturing the sup rim of the patch to the lower rim of the ASD, avoiding injuring the conduction system and His bundle- carry the suture line into the LA, adjacent to the L AV vlv, near the region of the CS, and use superficial bites at this region. Some rec placing the CS into the LA by carrying the suture line of the ASD up and around the CS. Both --> similar freq of AVB (Ref 15)
Two-Patch Technique
-Dacron or PTFE to close the VSD
-suture the valve leaflets to the top of the VSD patch
-close the L AV vlv cleft
1) Long medial atriotomy
2) Check the distance bn the IVS crest and the superior aspect of the L AV vlv to assess the VSD size and form the patch, to ensure they AV vlvs are at correct height above crest of IVS to ensure no LVOTO
3) Anchor the patch to the IVS crest w interrupted sutures, placed on the RV side to avoid the L bundle and the AV nd. Espec in pts w Rastelli type C, the posterior common leaflet often must be divided to fully expose extent of the VSD. Then suspend the L AV vlv fr the patch after approximating the L sup and inf leaflets centrally. The L AV vlv is sandwitched bn the ventric PTFE patch and the atrial pericardial patches
4) Close the L AV vlv cleft created bn the L sup and L inf leaflets w interrupted sutures, carrying them to the insertion site of the first order cords at edge of the vlv
5) Ensure L AV vlv is competent by irrigating the LV w saline
6) close the ASD w a pericardial patch, w running sutures to anchor the patch, using superficial sutures by AV nd, close to the L sided AV vlv to avoid the conduction system
-the CS remains in the RA
7) repair the R AV vlv by closing the cleft bn the R sup and R inf leaflets, and approximating the valve edge to the ASD patch, then check competency w saline irrigation
8) Check TEE postop- (pre op eval R and L AV vlv size, competency, straddling of cords), post-op check for: residual VSD, residual ASD, L or R AV vlv regurg or stenosis
Modified Single-Patch Technique
1) close VSD w sutures on R side of IVS, then pass them thru the ant and post common leaflets at a predetermined site to separate the L and R AV vlvs. The most posterior septal suture are placed first, lateral to the free edge of the septal crest, and then brought thru the base of the posterior common leaflet. The sutures in the ant part of the septal crest are then placed, w the most anterior sutures placed first, then go in centrally.
2) Once all the sutures are placed thru the leaflets, pass them thru a thin strip of Dacron to reduce the length of the septal crest enough to incr the central copatation of the ant and post leaflet components (optional).
3) Then, suture thru the edge of a pericardial patch & tie them--> eliminates the VSD; now you just have a primum ASD to close.
4) Step 3 creates a cleft in the L AV vlv by apposing the ant and post common leaflets. Close the cleft w sutures, to the pt where the cords attach fr the pap muscles reaches the edge of the leaflet...
5) Test the valves for competency w saline irrigation
6) Close the primum ASD w the pericardial patch w running sutures following the edges of the defect except in the region of the AV nd. By the AV nd, the suture line skirts down into the LA, adjacent to the L AV vlv annulus, and close the the L AV vlv leaflets until a pt lateral to the triangle of Koch is reached. Then the suture line crosses up the edge of the rest of the atrial septum, allowing CS to remain in the RA
Surgical Results
-Similar for each type of repair
-Single Patch Repair (Ref 34-36)
-used by Boston, UCLA, Vanderbilt
-Boston study- +double orifice LV is a R/F for death (Ref 34)
-UCLA study- 60% of them also had L AV vlv annuloplasty (Ref 35)
-Advantages: simple to do
-Disadvantages: often need to divide the AV vlv for effective exposure--> decr vlv fx, and higher risk of residual VSD pr aneurysm (slightly)
-Outcomes (operations bn 1970s-1990)- 3% death at boston, 7% UCLA, 15% VAnderbilt; L AV vlv regurg in 6-9%, HB needing pacer 2-4%, LVOTO 1%, residual defect 0-5%
-Two Patch Repair
-Meta data fr Chicago, Munich, Berlin, Indeanapolis, Melbourne (1990s)
-Mortality 7%, reoperation 8%, HB w pacer 3%, LVOTO 2%, residual defect 3%
-Advantages:
-Dacron/PTFE is of less risk of aneurysm over time as oppose to pericardium (ref 32)
-Low freq of residual VSD bc of interrupted sutures technique
-Less SubAS if use properly shaped PTFE patch
-Less patch dehiscence w use of sandwich technique for L AV vlv bn PTFE and pericard. patches...
-Disadvantages
-residual ASD that strikes PTFE/Dacron--> hemolysis, unlike w pericardial patch
-more HB- pericardial patch is more maliable so less torsion at suture line, so less heart block
-reoperation- Mavroudis recs closing the cleft, and not calling it a Nl trileaflet L AV vlv bc reop is often for L AV regurg, most often bc of incompletely closed cleft (Ref 39, 40, 41)
-Modified Single-Patch Repair
-Nunn (Melbourne, 1995, Ref 42, 76 pts): 2.8% operative mortality, no signif postop residual VSD, but trivial VSD not needing reop in 20%, L AV vlv fx Nl in 66%, mild L AV regurg in 29%, mod L AV regurg in 5%, and no early LVOTO w median f/u 3 yrs; no late AV vlv repairs/replacements
-Overman *Minneapolis, Ref 43, 30 pts): same outcome as 2 patch, w no mortality in past 10 yrs, no incr in LVOTO, but mild selection bias bc if the VSD was large they used the 2 patch technique
-w early f/u studies- no decr in vlv fx, and low incidence of AV regurg
-Advantages:
-may have better AV vlv competency outcomes
-better for smaller infants/neonates w CHF, easier to do
(Preferred by the Mavroudis group for Rastelli A, but for Rastelli C they still use 2 patch technique)
Risk Ractors
-Operative Date- better if done more recently..., maybe bc of inhaled NO use for phtn (Ref 44)
-Age at Operation- delaying repair --> worse outcome. Best to do it at <6mo bc it --> incr survival due to less postop phtn (Ref 15, 25)
-Preop AV vlv incompetence- sev L AV regurg --> worse phtn and impacts hospital death p repair )Ref 38,39). Sev AV regurg preop might not be amenable to a good repair
-Cleft closure- routine cleft closure--> less need to reop for L AV regurg (15, 35, 39)
-Down syndrome- more often have redundant AV vlv tissue avail for reconstruction--> less postop AV regurg, and maybe better outcome (Ref 24, 25). (86% of AVSD pts have Downs, Ref 15)
-Postop mgt- paralysis, sedation, hyperventilation used by Mavroudis group to avoid pulm htn crisis, improve CO in first 24-48hrs. Avoid hypoxia, hypercapnia, acidosis, pain, hypothermia
-sedate/paralyze for 1-3 days postop to avoid phtn
-Tx phtn w iNO or inhaled prostacyclin (Ref 46)
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