Truncus Arteriosus (M/A)
-usually isolated
-some assoc w 22q11del, maternal DM
Embryology:
-Embryonic TA is bn conus cordis and Aortic Sac & Ao arches distally
-TA partitioning is closely related to conal and Ao-Pulm separation
-Truncus Swellings divide the truncal lumen--> Proximal Asc Ao, & Pulmonary Trunk
-Proximal part of the truncal septum fuses w the conal septum (derived fr conal swellings), and the RV origin of the pulmonary trunk, and the LV origin of the Ao are established.
-At site of fusion bn truncus and the conal septum, valve swellings dvp fr the truncus, and form the Ao & Pulmonary Valves
-At Ao Sac, the 6th Ao Arches (primitive PA's) move leftward, and the paired 4th Ao Arches move right
-The Ao Sac roof invaginates to--> the AoPulm septum, which fuses w distal end of the truncl septum
-R & L PA's originate fr the pulmonary trunk, and the Ao Arch comes fr Asc Ao.
-The truncoaortic partition spirals to --> the Nl intertwined GA's
-Truncus Arteriosus = single art trunk fr heart
-bc defic/absent conal (=infundib) septum to --> large VSD
-bc conal septum contributes to --> ant tricuspid leaflet & med tricuspid pap muscle, they will also be malformed
-The single truncal valve may be malformed, regurgitant, or stenotic
-PA's can arise fr a short pulm trunk together, if there had been some distal truncoarotic septation, otherwise they arise separately fr the truncal root
Path:
-Single artery to --> coronaries, PA's, systemic arteries
-Single semilunar valve
-This is what DDx fr Ao & PA atresia (where 1 artery also gets both CO's)
-Types (Edwards)
-I (50-70%) = short pulm trunk fr the TArt, then --> 2 PA's
-II (29-50%) = both branch PA's arise separately fr TArt, w no MPA, and arise close to each other
-III (6-10%) = " " " " " " ", " " ", and arise far from each other
-IV = PAtresia + VSD (new type, not discussed here, see other chapter)
-Van Praagh Classification
-Type A1 = Edwards Type I
-Type A2 = Edwards Type II & III
-Type A3 = one of the PA's don't arise fr the TArt, but gets Q fr the PDA/collaterals
-Type A4 = underdvpd Ao Arch (tubular hypoplasia, discrete CoAo, or complete interruption)
-VSD
-usually large, bc absent/defic infundib septum, bn the 2 limbs of the septal band, roofed by the truncal valve cusps (see pic)
-Usually, the inf limb of the parietal band is fused--> muscular discontinuity bn the TV and the Truncal valve. Thus, the membranous septum is intact; it's an infundib VSD
-If there is no such fusion, then the tricuspud vlv is in continuity w truncal valve, and defect will involve membranous septum, and thus is both membranous & infundibular.
-Rarely is the VSD small/restrictive or even absent
-Truncal Valve
-Usually tricuspid (70%), or 4 cusps (22%), rest mainly bicuspid but some 5 cusps.
-It is in fibrous continuity w mitral valve in all pts
-It is in fibrous continuity w tricuspid valve only in some (if the septal band didn't fuse w parietal band)
-Usually biventricular origin (70%), w most of the rest fr RV, and some fr LV only
-Truncal Insufficiency
-thick/nodular dysplastic cusps, prolapse of unsupported cusps/conjoined cusps w a shallow raphe, unequal cusp size, minor commissural abNly, or annular dilation.
-Truncal stenosis
-usually w nodular/dysplastic cusps
-Truncal root often dilated, and sinuses often poorly dvp'd
-Ao Arch
-R Ao Arch in 20-35%pts (2nd only to PA+VSD)
-Arch hypoplasia +/- CoAo in 3%
-Interrupted Arch in 10-20%pts, w ductal continuity of the Desc Ao; esp w DiGeorge
-DA
-absent DA in 1/2 pts!!, but if present, 2/3 of these pts will have PDA
-Larger DA correlates to smaller Ao and vice versa (e.g. big PDA if small Ao...)
-Shiraz: presence of PDA- nearly always see an interrupted arch or a PA off the PDA
-PA's
-Usually fr L Post side of the TArt
-In type II, LPA os is usually higher than RPA os
-Rarely are their ostia stenotic
-Thus, unless you band the PA's, the lungs will be exposed to systemic pressures
-Rarely, deformed truncal valvar tissue will obstruct pulm ostia w ventric systole
-One of the PA's may be absent (16% in one series), more often on same side as the Ao Arch
-DDx- w TOF the PA is often absent on side opposite the arch
-Coronaries
-Important to know their origin/course for surgical prep; much variability
-LAD
-often small and displaced to the left, --> RCA conus branch compensates and is prominent, supplying some large branches to the RVOT (Important bc this branch might get in the way of a conduit...)
-Post Desc CA's arise from L CMX (=L cor dominant) in 1/4 pts (3x the usual rate for Nl pts)
-1/3-1/2 of pts w TArt have coronary ostial origin
-LCA tends to arise fr L post-lat truncal surface, & RCA fr the R ant-lat surface
-Single Coronary Artery
-All 3 epicardial branches fr one common site, or RCA is absent
-2 Ostia
-both might arise fr the same sinus, one may be fr a noncoronary sinus, or may be Nl...
-Often high origin, above STJ, can be slitlike
-Rarely, LCA might come fr the pulmonary trunk
-Conduction Tissue
-SA nd & AV nd are usuually Nl
-AV bundle- runs to the L of the central fibrous body,
-LBB emanates along the LV septal subendocardium, just beneath the membranous septum
-RBB runs within myocardium of ventric septal summit, stays subendocardial at level of moderator
-If the membranous septum is intact (bc VSD is infundibular), the AV conduction tissue is somewhat distant fr the rim of the defect. But, if the pt has combined membr-infundib VSD, then the conduction tissue passess along the L side of the posterior-inf rim of the defect.
-Secondary xx
-biventric hypertrophy, dilated venricles if TArt regurg, ch subendocardial ischemia if much hypertroph
-pulm htn if prolonged exposure to systemic pressures
Sx/Si:
-Usually fetal/neonatal Dx
-Initial high PVR--> mild cyanosis, and may resolve w decr PVR/weeks
-But, tachypnea/tachycardia/diaphoresis/poor PO/other pulm overcirc Sx can start as PVR drops
-W incr Qp, --> vol load on heart
-If there is natural PA stenosis (uncommon), cyanosis at birth may incr w age, but it can protect pt from pulm overcirc as PVR drops.
-Can have sev cyanosis + pulm overcirc Sx/heart failure Sx--> can present early if pt has PA stenosis and sev TArt vlv regurg.
PE
-Bounding periph pulses- bc of runoff into pulm vasc bed during diastole
-L precordial bulge
-Systolic thrill common at LSB
-"Overactive heart"
-Nl S1, w ejection click (w the maximal opening of truncal valve)
-S2 loud & single
-S3 common
-Loud pansystolic murmur, loudest at LLSB w rad all over; apical diast low pitched murmur bc of incr Q thru mitral vlv
-If TArt Regurg, usually--> diastolic high pitched murmur, loudest @ LSB
-Continuous murmur (uncommon)--> c/s PA ostial stenosis
-Consider DDx: PA+VSD bc of PDA or collaterals--> continuous murmur
-If Heart Failure--> tachypnea, rales, hepatomegaly, neck vn distention
-+Cyanosis, clubbing if decr Qp bc of PA stenosis, PA band, or pulm vlv dz
-If no TArt Regurg: Nl periph pulses and PP if there's, no diastolic murmur, and less Sx of hrt failure...
ECG:
-minimal RAD -NSR w Nl conduction times
-combined ventric hypertrophy
-Prominent LV forces if incr Qp
-LA Enlargement common
-RVH alone if Nl/decr Qp
CXR:
-moderate CM, incr pulm vasc markings
-R Ao Arch in 1/3 pts
-Thus if u see R Ao Arch + incr pulm vasc markings--> c/s TArt
-Type I- often see ~ superior LPA location prox'ly
-Dilated truncal root
Echo:
-Subcostal
-check abdominal/atrial situs, cardiac apex position
-see single GA fr heart (see pic)
-check for ASD
-check TArt vlv fx
-check Truncal root & PA branch anatomy
-PSLA
-check VSD, overriding Ao
-see continuity bn truncal vlv and mitral vlv
-see Pulm trunk origin/branches fr slightly higher view
-High PSSA
-See PA's arise directly fr post-lat side of truncus, w bifurcate to R & L branches...
-Check for a short MPA (Type I), or separate PA's fr truncus (Type II), single PA off trunc (III)
-PSSA
-Check truncal leaflet anatomy (#/morph)
-Check coronary anatomy
-Check VSD location/extension
-Suprasternal
-Check Arch anatomy- interruption/hypoplasia, R Ao Arch
-Check PA branches, r/o branch stenosis
-DDx an AP window w echo
-AP window- not assoc w VSD, RVOT and pulm vlv are in Nl positions; can see the window w high parasternal view
-Doppler- check degree of Truncal vlv stenosis, check for regurg
-If regurg+, the Doppler may overestimate amt of stenosis bc of the increase volume across the vlv
-check for flow reversal at abd Ao, bc of PA runoff or truncal vlv insuffic
Cath/Angio:
-usually not needed, but may need to check AO arch (if interrupted) or PA tree (if single PA)
-might need to check PVR
-If pulm art resistance >8unit/m2 --> higher operative risk; w late deaths due to pulm vasc dz and qy sev phtn w RV failure
MRI:
-helps assess anatomy/hemodynamics
DDx:
-TArt + incr Qp << CHD w early heart failure and cyanosis
-VSD, PDA, AP window, PA+VSD, PDA, large collats, DORV, univentric heart, TAPVR
-TArt + decr Qp<<
-PA, TA, TOF, univentric hrt w PS, DORV w PS
NHx:
-Some survive to adulthood w/o surgery, but usually most die by avg 5 weeks old; 15% survival at 1yr
-Die fr heart failure; also phtn & infective endocarditis
-rapid decline p phtn starts
-thus, Tx early!
Tx:
-Delaying OR --> ch ischemia of hypertrophied heart, (esp bc the blood in coronaries is desaturated bc of mixing, and the diast P is low bc of runoff to PA's & bc of TArt regurg)
-Thus repair at 6-12mo --> 2x mortality risk than for 6wk-6mo old
-Pulm vasc dz can dvp early, so correct at <few months old, as it plays big part in mortality
-Goal = complete repair as a neonate
-PA band may be needed but it can be risky, and a good band doesn't mean they'll make for a good surgical candidate later on...
Surgery
-1st done in 1967 w an Ao homograft bn RV to PA's
-by now, operative mortality is 5% if pt doesn't have severe assoc xx
-Pt will get conduit placed as neonate, then need replacement later on w bigger one, but replacement has a low risk
-Most surgeons prefer a valved conduit bc of the presence of phtn
-For conduit replacement, M/A Preference = Peel Operation = Autologous tissue reconstruction to reconstruct RVOT:
-Place a prosthetic roof (bovine pericardium) over the fibrous bed of the explanted conduit, and insert a prosthetic valve.
-If TArt Regerg--> usually amenable to repair, so don't need to replace as a neonate
-suture the prolapsing leaflet to adjacent leaflets (easier bc they are usually thickened)
-Late results d/o degree of TArt regurg and the need to replace the conduit
-may need to repair TArt regurg that dvps later in life...
-In one study, 25yrs post op- if there was trivial/no regurg at time of correction, they didnt need to get truncal valve replaced
-Late problem of an extracardiac conduit-
-must be replaced as pt grows; deteriorating conduit, Calcification
Long Term Issues:
-Need life long f/u
-+SBE ppx needed
Anderson Lecture Notes 10/2012
-Must DDx common art trunk from a Solitary Arterial Trunk- latter has PA's entirely outside pericardium, thus can't presume that the artery was meant to be an aorta, so can't call it an aorta...
Fundamental feature of Common Arterial Trunk = common VA vlv
Variable features:
-Rarely is the IVS intact
-apposition of valve leaflets on the septal crest is not the same as an intact IVS
-anticipate a sub truncal defct
-note how it is similar to a doubly committed VSD
-may have a muscular postero-inf rim, may have a truncal tricuspid continuity (= PM VSD), or may have an AVSD in addition to the Common art trunk
-note the AV conduction location variation based on VSD type...
-Origin from ventricular mass
-may override IVS,
-may come fr RV exclusively in which case often only a restrictive VSD w intact subarterial region, and instead it is a PM VSD...
-TV
-most often 3 leaflets, also possible 2-4 leafs...
-+/- dysplastic leaflets
-Variations in systemic and pulm art pathways
-usually Ao dominates
-usually when PA's arise fr Ao, they come off fr the L and post part of trunk, and directly adjacent (bn type 1 and type 2, so call it type 1.5...)
-but PAs might come more antly and cross each other, or rarely fr the truncal valvar sinus, or be discontinuous PAs w one fr the arterial trunk and the other from the PDA
-if Pulm dominance (rare), see larger PA component, w confluent PAs, and hypoplastic Ao, see interrupted Ao arch or severe CoAo..., thus see PDA...
-PA origins vary when you have pulm dominance, but usually arise fr a confluent pulm segment, have a PDA and signif Ao coarc vs interrupted Ao arch w PDA major path to desc Ao
-Aortic Arch arrangement
-R sided in 1/3 pts
-interrupted or coarc if pulm dominence
-may rarely have Ao and PA size similar, with balanced Q...
-PDA
-seen w pulm dominence, to feed distal Ao
-or see w Ao dominance and discontinuous PAs
-rarely does it exist when you have balanced PA and Ao size
-Coronary Arteries
-even if truncal vlv had 3 leaflets, it is still not Ao bc cor art anatomy varies
-often arise above ST jct, and may be near the PAs (so beware surgically...
DDx
-solitary art trunk
-AP window
-see a common intrapericardial segment, but with separate Ao and PA roots (!)
-Ao origin of one PA (NOT TRUNCUS, and DON'T call it hemitruncus
-e.g. Ao origin of RPA, see common VA jct
-best to describe/categorize based on Ao and PA dominance, then describe PA origins...