-estimated 4-9% of CHD (???really)
-ref 1 -New England Regional Infant Cardiac Program 1980 report- 7.5% incidence among CHD
--> 25% of deaths fr CHD at <1week old before PGE in 1970s
-1990 - birth prevalence of hLHS 0.162/1000 live births, same as the New England report
-Morris et al - 600 infants /yr born w HLHS in US
Embryo
-?abNl septum premum more L ward--> abNl L Heart dvpmt
Anatomy
-undervpmt of L side
-MS or MA
-AS or AA
-Boston study, n=78 - 35% w AA/MA, 20% AS/MS
-In AA, asc Ao is only 2.5mm as neonate, while w AS it is often 4-5mm
-usually narrowest at jct w arch and innom artery
-Arch very variable in length, and degree of hypoplasia
-+/-interruption
-diam of prox arch is usually similar to the distal arch, bn 3-5mm
-coarctaion shelf opposite the jct of the DA and prox disc Ao seen in 80% of pts
-large PDA, directly extending off the MPA, which is usually large (11-15mm)
-they note PAs to be on the smaller side, bc if decr Qp in utero bc of L sided obt
-small LA, muscularized septum primum
-+/- restrictive FO
-+/- thick, fibrotic LA, een affecting PVns--> stenosis
Assoc xx
-5% of AA pts have a VSD
-often assoc w Nl or near Nl LV size --> ?bv repair...
-bicuspid pulm vlv seen in 4% in one series
-pulm vlv dysplasia and cleft TV seen in 4%
-one report of >50% of pts w MS/AA had cor art stenosis, rare w ma/aa
-CDH, hypospadia, omphalocele, CNS xx (eg agen of corpus callosum, microceph)
-genetic xx common
Pathophys
-in utero, likely less Qp than Nl for fetus, bc of LA egress is obstructed
--> RV CO goes thru DA, antegrade down desc Ao or retrograde to Ao Arch/head vessels/Asc Ao
-PVR drops after birth, but in HLHS pulm arteriolar smooth muscle is increased
-likely Sn to pH and FiO2
Sx
-......
Dx
...
Rx Tx
-PGE
-avoid incr FiO2
-correct acidosis..
-BAS if needed...
Surgical Indications & Timing
-Dx = indication
-relative c/i xx is premie <34 wk GA, LBW <1500-1800gm, serious chrom xx, though they are very rare to contraindicate surgery
-sev TR or PR, and sev RV dysfx may be a c/i xx
Surgical Timing
-Boston - 2-3 days of resuscitation, not common to go to OR sooner
-if pt is failing fr very high Qp:Qs.... then go to OR in <24 hrs fr Dx
-if sev hypoxia fr restrictive ASD, go to cath lab ASAP
Surgical Mgt
Stage 1 - Norwood
-...
-median sternotomy
-partial thymus excision
-cannulate the mid ductus and RA appendage
-hypothermia
-divide prox MPA 2-3mm above the PV
-direct suture close the MPA
-construct the Sano shunt- PTFE tube graft ... bn LPA and MPA stump
-apply a homograft to the Ao arch
-circ arrest- off bypass, admin cardioplegia
-remove arterial cannula
-divide the PDA
-fillet open the Ao arch and Asc Ao to the level of the MPA
-anastomose the prox part of the MPA and the aorta w a cuff of homograft
-ensure the Ao is not redundant, and does not create a 'bowstring effect' over the LPA --> compress bn neoaorta nd L main bronchus
-avoid cor artery compromise
-don't block Q to them
...
-Atrial septectomy - via RA incision
-excise the primum septum fr the base o the FO down to level of IVC
-don't do a partial excision, it --> restriction later on
-Shunts
-Mavroudis prefers the Sano (RV to PA bifurcation w PTFE
--> Q during systole only, unlike BT shunt --> no competition w coronary Q...
-Sano
-5mm Sano shunt for neonates 2-3.5kg, 4-6mm if >3.5kg
-c/s larger tube if higher PVR...
-Avoiding a homograft cuff
-Norwood initially did not use a uff, and this has become popular again lately, but they still use a cuff thinking it is not good to have direct anast of prox MPA to the arch bc it requires more distal division of the MPA. This is because prox MPA division allows the distal end be used for direct closure of the PA, thus better growth in the 'critical mid-PA region'. Also, direct anast --> possible bowstring effect of the aorta over the LM bronchus--> air trapping in L lung. They feel Ca'ion of the homograft is nearly never an issue.
-Minimizing/Avoiding Circ Arrest
-above technique expect circ arrest for <30-40min, but some techniques allow for now circ arrest, though they say their is no developmental advantage to avoiding circ arrest (ref 37). Alt techniques rely on 'unprooven' techniques like retrograde Q thru the BT shunt --> but risks that the Q is not homogenous (Ref 39), thus --> false sense of safety by surgical team...
Proximal Sano Shunt Anastomosis
-can construct the prox Sano shunt anast when bypass is re-established
-oblique incision into infundibulum of RV, avoid cor arts and PVlv
-point it L and sup so to direct the conduit into the L chest where it is less likey to be compressed by sternum
-bypass wean
-unlike w BT shunt, no necessary to control Sano Q during rewarming
-...
Follow Up after Stage 1 Surgery
-...
Two Ventricle Repair of Aortic Atresia with VSD
-perform both a Norwood and a Rastelli
-reconstruct neoaorta under circ arrest
-don't close the distal divided MPA. Instead attach a homograft to the distal MPA
-place a patch/baffle in RV so that LV Q is directed to PV thru the VSD
-anast the RV to the PA homograft
Bidirectional Glenn Shunt & Fontan
-See Mavroudis Ch 20 [[?ch 40]] on Single ventricles
Surgical Results
-Ref 40 - CHSS 2003 study = largest outcome of stage I Norwood
-n=985 neonates 1994-2000 w crit AS or atresia
-710 had Norwood
-Survival- 75% at 1mo, 60% at 1yr, 54% at 5yr
-death r/f = lower BW, smaller Asc Ao, older at Norwood, institution w <10 Norwood or >40 neonates (in 2 cases), procedural variables- shunt originate fr aorta, longer circ arrest time, technique of Asc Ao mgt
-by 18mo p Norwood, 58% had Glenn
-of these, 79% successfully got to a Fontan within 6 yrs
-r/f for death at Glenn- younger age, need for R AV vlv repair
-Fontan mortality: 9%
-3% got an OHT
-Since Norwood was first done in 1983, survival has improved much.
-CHSS report reports a 1 month survival of only 72%, but this had large # of sites (>40 hospitals) , many early on the learning curve.
-ref 41- Daebritz - n=194 Norwood bn 1990-1998 at Boston -
-131 HLHS, 63 other single ventricle w systemic outflow obst
-21% operative mortality after 94 (decr fr 38.5% in early 90s)
-Sano introduction in 2002 reduced Norwood mortality to <10%
-ref 42- Mahle CHOP outcomes
-n=840 Norwood bn '84-99
-initially 44% mortality in 1980s, 29% bn '95-98
-ref 43- Bove Michigan - n=253 Norwood bn '90-97
-24% hosp mortality- influenced by noncardiac congen xx and by sev pre-op pulm vn obst
-Glen/hemiFontan survival 97%; Fontan survival 88%
-ref 44- Tweddell 2002 study- n=115 at Milwaukee '92-01
-47% hosp mortality till '96, then 93% hosp survival - emphasize continuous monitoring of syst vn O2 to improve Norwood outcome
-ref 45, 46 Toronto and Birmingham UK
Norwood + Sano Outcome
-2003 Malec (ref 47) - Poland n=68 Norwood , 31 w BT shunt - mortality 35% while remainder w Sano had 5% mortality
Devo Outcome
-ref 48 - Wenovsky n=133 who had a Fontan at Boston
-mean IQ 96
-HLHS Dx --> worse IQ
-other risks of lower IQ: long circ arrest,
-more important was the technique of circ arrest- prev had alkaline pH, sev hemodilution, rapid cooling, and relatively short pd of cooling all done x3 surgeries--> all likely contributed to the worse outcome, rather than the Dx of HLHS per se...
-ref 49 - Goldberg- Michigan- IQ
-Wechsler score of 94- lower in pts w/ HLHS compared to those w Fontan for another Dx (IQ 107)
-circ arrest use, periop seizure predicted worse outcome
-refe 50 - Eke- Loma Linda, CA
-Bayley psychomotor dvpmt was 91 and mental dvpmtl index 88 (Nl is >100)
-ref 51- Denver- similar findings....