Assoc xx
-PDA
-VSD- 20% TGA pts
-usually 1/2-2/3 MPA diam
-may have some malalignment w SubAS/small Ao annulus
-may have hypoplasia of RV, TV, Ao Arch, CoAo, InterrAo
-if post malalignment of VSD, then see PA annulus hypoplasia, posse vlv PS or bicuspid pulm vlv
-20% of pts w TGA+VSD have LVOTO at birth, but it may dvp late, up to 35% of all pts w TGA/VSD
Isolated LVOTO (w/o VSD)
-may be fx;, bc septum bulges into LV bc higher RV P, and improves p ASO, but over time can progress fr dynamic obst to fixed/fibrous tunnel like LVOTO
Coronary Anomalies
-Coronary Ostial Abnormalities
-ostial atresia/stenosis
-Intramural cor arts
-Single cor ostium
Branching patterns in d-TGA
-Leiden convention- # cor art as if you are in Ao looking at PA- 1 is at R hand, 2 is adjacent to PA/on left hand, then abbreviation of the core art…
-Yacoub & Radley-SMith convention- usual - type A, single cor ost Type B…
-see pics
-Boston recs just describing it bc so many variations…
…
Pathophysiology
-tga physiology…
Pulm Vasc Dz
-get phtn much faster, even by 6mo, may be inoperable by 12mo…
LVOTO
--> sev cyanosis
Reverse differential cyanosis = TGA +Arch obst.
-if CoAo or InterrAo, then Q to lower body is maint by PDA, coming fr the LV via MPA so it is fully saturated. Q to upper body is fr Ao fr RV and is desaturated --> pink toes and blue fingers
Sx/Dx
-hypoxic, acidic as PDA closes in first days of life
-XR showes incr Qp despite cyanosis
-egg on string on CXR bc ao is ant to PA --> narrow sup mediastinum
-dx by echo
Medical Tx
-BAS within hours of life if no ASD or VSD
-PGE alone- possible, but often --> systemic steal, spec and organs, so r/f for NEC
-Because it's a parallel circulation, and L-->R PDA Q will go to pulm circ and --> LA hypertension if no bidirectional shunt, thus BASwill help decompress the LA w Q to RA fr ASD
-Prefer to obsv for couple days in CICU prior to repair, to allow recovery fr birth, and any xx fr PDA closure, hypoxia/acidosis
-Follow for renal, hep, GI, cerebral fx
-No need to intubate
-If poor mixing, and s/p BAS, c/s restarting PGE
-No need for a-line, pulse ox is enough
Surgical Indications & Timing
-Dx = Indication
-If late Dx, how late is too late for 1y ASO repair?
-if large enough VSD to ensure the LV sees at least 2/3 systemic P, then LV will be prepared for ASO
-if intact IVS, then after a few wks, LV get's thinner, and by 3 weeks old, likely too thin to do 1y ASO (ref 23), though later reports have suggested that w current experience level and mechanical ventric support, can go up to 8 wks w repair (ref 24, 25)
-after 8 weeks, then do a 2 stage repair (PAB first)
Surgical Mgt
Arterial Switch Operation
-resect thymus
-cannulate just prox to innom artery, and at tip of RAA
-dissect and ligate the PDA
-cool to <18C
-mobilize PAs to hilar branches
-Ao Cross Clamo
-Cardioplegia to Ao root
-Divide Ao at midst opposite the PA bifurcation
-Excise cor arts w buttons & mobilize first 2-4mm of cor art
-Divide PA just prox to bifurcation
-Lecompte maneuver- bring PA bifurcation ant to Asc Ao
-Excise U shape fr prox neo-Ao to replace cor art buttons; replace them to neo-Ao
-Ao anast w continuous suture, and mattress sutures by cor art suture lines
-reconsturct prox neo-PA w periardial patch
-circ arrest
-RA free wall incision- close ASD
-release Ao cross clamp
-ensure perfusion well to all areas
-do PA anastomosis
-rewarm
-LA line
-pacing wires
-bypass wean
-RA line
High Risk Coronary Arteries
-Single Cor Art fr Post Facing Sinus w post LCA
-
……..
-presence of bicuspid neo-Ao (old PA) vlv not an absolute c/i xx to ASO
-if z-score of valve -2.5 to -2 or btter, likely okay
-if sev LVOTO, c/s Rastelli or Nikaidoh
D-TGA w Interrupted Arch or CoAo
-if +, then look at RVOT, RV volume, TV size closely
-RV small, or TV smaller than -2.5 to -3 z --> do a single ventricle repair
-if neo PA annulus is smaller than -2.5 to -3 z, c/s a transannular patch, +/-RV-PA conduit if cor art crosses infundibulum
-Fix Ao Arch when you do the switch, via direct anastomosis
-if needed, pericardial patch to arch
-repair w hypothermic circ arrest
Surgical Results
-Congen Heart Surgeons Society Study
-ref 38- n=829 neonates, 24 institutions, 1985-1989
-516- ASO, 285 atrial repair, 28 Rastelli
-2.5% of the deaths were pre-op
-ongoing late risk of death is higher for atrial level repair than ASO
-Congen Heart Surgeons Society Study 1997
-ref 39- report on OTO post ASO
-RVOTO late incidence = 0.5%/yr, much greater than if Ao root reconstruction (0.1%/yr)
-r/f infundib obstor pulm vlv obst:
-side-side relation of GA, +CoAo, prosthetic material at sinus reconstruction site, earlier surgery, institution
-PA/Pulm Root obstruction
-r/f- lower birth wt, LCA fr R'ward or post sinus, cor explantation using a circular button separate fr transection of Ao, earlier surgery date, institution
-Boston experience
-Ref 40&41- 1998 review of their results
-ref 16- low rate of SBT or other arrhyth
-specific cor art anatomy may--> more risk
-Cor Art Anatomy & ASO Outcome
-ref 30, 43, 44- studies on cor art r/f for outcomes...
-Quagebeur- s66 pts, no impact of cor art pattern on outcome by MVA, 5 pts had a single R or inverted cor art pattern; 1 late death ? why in pt who had single RCA
-ref 43- Mee/Brawn- 50 pts, 11 had serious cor art transfer problems, one pt died early postop for cor art xx who had inverted cor arts
-ref 44- Serraf - 432 pts in 80s mainly- incr risk if any cor passed bn the GAs
-ref 47- 513 pts sp ASO,
-cor art is a r/f- LMCA or LAD or Circ fr R/post facing sinus = r/f
- intramural course - nearly always arose fr os near commissure bn the 2 post facing sinuses
-ref 48- Daebritz 2000, Germany- 312 pts in 80-90s, single cor art fr either post facing sinus, w LMCA pass behind PA, or single cor art fr L post facing isnus w RCA passing ant to Ao --> risk
-single cor ostium--> risk
-ref 55- Boston 1990 - could not demonstrate incr risk fr an intramural course
-but UCLA ref 49- 70 pts w ASO w intramural cor art- greater M&M fr ischemia
-ref 50- 1999 Boston- 223 pts in 1990s-
-7% (16) early deaths (2.7% risk if pt was considered 'low risk' (by cor art/Ao anatomy etc)
-cor arts didn't affect outcome
-Boston surgical results
-1983-2000: 844 pts, s/p ASO
-6.3% w single cor art
-13% (7 pts) of these died, but none since 1991
-if singe R ostium w circ or LMCA behind the PA- 8x incr risk of death compared to other single cor arts for early death
-side-side GA had 6x risk of death
-Toronto 2000, ref 51- 38% mortality if TGA, itnact IVS w single cor art, and 41% if TGA/VSD, but in the last 2.5yrs of the study, it was 0% mortality...
Late Coronary Problems after ASO
-ref 52- 1996 study Paris- n=165, 12 cor art occlusions
-ref 53- Boston - 3% of pts of 366 pts had cor art xx an avg 6 yrs p TGA, by cath, in pts prev thought not to have cor art xx...., of these 13 pts1 died suddenly at 3yrs postop, 1 lost to f/u, rest ok
Developmental Outcome After ASO
-ref 38- incr risk of psych xx, espec LD, but this is fr late 1980s w long hypothermia and circ arrest... more hemodilution, higher pH, higher periop neuro xx
-ref 58- RCT of pH- TGA had better mental and psychomotor outcomes compared to TOF or VSD, likely in part bc less DiGeorge synd pts, and may reflect era effect/bias as well
-goal to keep Hct >25-30, and limit hypothermic circ arrest, ref 59
Two Stage Arterial Switch
-PAB + either RV-PA conduit or BTS, for pts w late presentation
-but xx dvp'd initially after delaying 2nd surg for months- scarring/adhesions dvp'd, make cor art anatomy more difficult...
-later work determined that a much sooner 2nd stage would be sufficient/better
-Indications for 2 Stage ASO
-if pt presents >4-8wks old, w LVP <66% systemic P
-if LVP maintained by a PDA or VSD beyond the immediate neonatal pd, it may be possible to do 1y repair later
-may also be indicated if pt has failing Senning/Mustard- ref 64; w some success beyond teenagers, but generally the author recs heart transplant bc results are poor
-signif risk of VF, St changes - ref64
-Technique
-3.5mm BTS
-PA band...
-Interval period
-stage 1--> large volume load on systemic RV, so may need much help postop... - ref66
-1/3 babies need to remain intubated, get inotropes thru 5-7 days postop, 1/3 little difficulty
-by 5-7 days, LV should recover Nl fx
-Boston '86-88- 11 pts, mean stage 1 at 4.5 months, median 9 day interval pd b4 ASO
-LV mass increased by 85%
-mean lV to RV P ratio incr fr 0.5 to 1.04
-no deaths in 10 pts who had an ASO
-1 pt had a Senning bc of intramural cor art
-relative to 1y ASO pts, LV fx and contractility was slightly reduced