Mavroudis - TOF

TOF Mavroudis22

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[ ] ant displaced IVS w unrestrictive VSD & overriding Ao w + MV-Ao continuity (DDx DORV)

[ ] pulmonary valve leaflets- obstructed? annulus size? atresia(7%)?

[ ] pulm arts- continuous? narrowed? origin of LPA off the PDA

[ ] PA-MAPCAS? (often present if no PDA)- see aberrant arborization by cath, likely periph pulm stenosis, not just centrally stenosed

[ ] check cor arts- LAD fr RCA in 3-5%, w LAD crossing RVOT just below pulm annulus, to get to the ant IVS, so at risk in the OR...

-alt cor art xx: dual distribution of the LAD- lower 1/2 supplied by the RCA, upper by the LCA, with large RCA conal branches; or single RCA --> LCA crosses RVOT

[ ] check for assoc xx: ASD, PDA, CAVSD, muscular VSD; less often: LSVC, anom origin LAD, aberrant PA origin

[ ] Absent pulmonary valve (5% pts) w rvoto fr annulus hypoplasia, sev PR, very dilated MPA/branch PAs--> compress distal trach/bronchi; no PDA

Presentation

-d/w degree od RVOTO... p/w progressive cyanosis shortly after birth...

-might first have CHF Sx if initially mild RVOTO w L to R shunting...; usually cyanotic by 6-12mo. in this case it is usually mainly infundib stenosis.

-others have cyanosis ~immediately postnatally, likely due to hypoplastic pulm vlv annulus +/- sev RV infundib hypoplasia or obst. Usually the periph PAs are good enough size

-may be PDA dependent for Qp

-if pulm atresia, then def PDA dependent or d/o collats- may even get pulm overcirc w CHF Sx...

RxTx:

-prevent tet spell by preventing dehydration, anemia, incr NE/E release, acidosis, decr SVR; tx spell w fluid, O2, sedation, bicarb, alpha agonists to incr SVR;

-can c/s long term beta blocker- propranolol, to decr contractility ?--> decr spell freq/severity; ?effective (ref 26)

Indications for & Timing of Surgical Repair

- don't need to Tx yet if sysemic Sa2 is ok

- Tx once hypoxemic to 75-80% or if pt gets any hypoxemic spells, though u caan try propranolol if you want to delay surgery...

- he recs repair by 3-6mo, though states that many institutions wait till 1-2yo (may be an outdated statement...)

-He recs shunt for: pulm atresia, marked branch PA hypoplasia, or sev noncardiac xx, otherwise do a single stage repair.

-previously, need for a transannular patch (TAP) for signif annular hypoplasia was c/s a c/i xx to early repair but this "has been neutralized" (ref 32-35)

Shunting Procedure

-BT Shunt (modified) is preferred

-Waterston (Asc Ao to RPA) & Potts (Desc Ao to LPA)--> hard to control Q thru it, phtn, and hard to take down when you do the complete repair later so PA gets distorted.

-Classic BTS- on opposite side of the arch (on ipsi side as the inomm art)--> best angle for SCA to reach the PA w/o kinking; less preferred in very small infants bc of small SCA size

-Modified BTS- PTFE 3.5-4mm shunt bn - low shunt failure rate; can be done on either side of arch, but right side preferred bc easier to take it down later; rare to have PA distortion, CHF, or phtn

Complete repair

-must know the:

[ ] size/distrib of branch PAs

[ ] size/condition of PA vlv & annulus

[ ] amt of RVOTO

[ ] cor art distrib

[ ] VSD anatomy

[ ] assoc xx presence

-midline sternotomy

-check cor art distrib

-avoid manipulating heart which can ppt a tet spell

-expose the syst-pulm shunt if present

-cannulate the Ao, just prox to innom art

-cannulat IVC & SVC, or if <3kg c/s just cannulate RA, but pt must be under deep hypotheria & circ arrest

-decr temp to 25-28C & vent LV via a pulm vn for CPB

-ligate & divide any shunts- to prevent later distortion

-mobilize MPA & Branch PAs

-ligate PDA

-Ao cross clamp

-Cardioplegia

-R Atriotomy--> assess the anatomy

-close ASD/PFO if present (leave PFO open in neonates in case pt gets incr RVP postop...)

-check VSD and RV anatomy via TV

-retract TV ant and septal leaflets w a suture, to see better the distal infundib

-check the position of the ant margin of the VSD & the position of the Ao vlv leaflets, and the parietal extent of the malaligned IVS

-if needed, divid down the muscle trabeculations on the ant limb of the septal band, to the level of the moderator band. In infancy, rarely do you need to resect the infundibular tissue...

-Pulmonary valvotomy- via RA approach. if inadequate exposure, then make incision in MPA for a PA approach

-Mobilize the PA vlv leaflets, and divide fused commissures

-check PA size w serial dilators

-place TAP if estimated RV:LV Pressure is > 0.7. If to place TAP, extend the MPA incision over the RVOT across the pulm vlv annulus. Can be a short incision, to just prox to the annulus, bc you already got rid of the infundib obst fr the transatrial approach. Try to incise at ant commissure of PV so you maint vlv fx

-close VSD fr transatrial approach- start sutures fr the at angle bn ant & post limbs of the septal band, then go superiorly over infundib septum & Ao vlv, w sutures thru ant leaflet of the TV. And then, going the other way suture inf'ly, past medial pap muscle, under the chordae tendinae of the septal leaflet..., w sutures on the RV side of IVS crest to avoid conduction system...

-can't close transatrially if diffuse infundib hypoplasia. - here you carry the VSD patch across the vlv to the PA

-rewarm, then assess for residual VSD, RV:LV pressure, & if high RV P--> use a TAP, if persists then c/s resid branch PA stenosis, hypoplastic periph PAs, resid infundib obst. If all neg, then likely it's ok and should improve in a couple days. might be bc of dynamic RVOTO, so c/s Esmolol....

PA AbNlies

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Hypoplastic PAs

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Pulm Atresia w MAPCAs

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TOF w Absent Pulm Vlv

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TOF w CAVSD

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Results

Mortality

-1-5% early in hospital mortality:

-Michigan in 1990s (n=217) 3.7% mortality, no change if repaired as an infant - likely bc of better intra-op technique- avoiding excessive RVOT muscle excision, better CPB, better post-op care

-Alabama (n=814) (Ref 32)- survival 1mo 93%, 1yr & 5yr 92%, 20 yr 87%. Incr risk if later age at repair or high RV:LV (>0.85); no change if used a TAP

Reoperation

-usually for sev PR, resid RVOTO, conduit failure (Ref 71)

-re-op for rsid VSD was uncommon, rec re-op if Qp:Qs >1.5

Heart block

-complete HB in 5% in early days of Tx, now <1%

Pulmonary Regurg

-doesnt affect mortality, but does affect fx (ref 7)

-inserting a pulm vlv for Sx'ic PR does improve Sx, decr RVP, reduce NYHA class

-early re-op for pulm vlv does improve fx, even if ASx- 1% operative risk (ref 84)