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Angio:
-best tool to Dx PPS
-AP view w cranial angulation and straight lat views show RPA and periph branches bilat
-prox LPA best w hemiaxial oblique views
-MPA trunk usually Nl or hypoplastic
-if sev unilat obstruction, then see delayed filling of that side's pulm veins...
MRI & CT:
-can replace Angios
-100% Sn&Sp
-MRA harder for peds bc motion artifact, bc you need pt to hold breath, and may need gen anesth.
-MRA cant tell 3rd-4th generation of PAs well
DDx:
-same as pulm valve stenosis
-c/s PPS if syst murmur w widely transmitted to axilla/back, but may have other CHD too...
-check for maternal rubella, familial CHD, prolonged neonatal jaundice, abNl facies (Noonan/Williams)
-c/s PPS in pts w TOF or other cyanotic heart disease
Tx:
-mild to mod isolated unilat or bilat PPS doesn't need Tx, but if sev, some need surg
Balloon Angioplasty
-first done in 1980
-Balloon should be 3-4x the diam of the artery (unlike valvuloplasty)
-Inflate to 1-2atm to ensure properplacement w a waist
-Then inflate more for up to a minute till waist is gone.
-Not as successful as valvuloplasty. Success if incr in diam by >50% and an incr of >30% in flow, or decr in RV:Ao P ratio by >20%.
-Overall success rate- 50-60%
-10-20% get recurrent stenosis
-Low pressure balloons have poorer outcome
-Complications- 5-15% w signif xx - hemoptysis, ipsi pulm edema, obstruction of dilated vssls by intimal flaps, pulm art aneurysms, clot at ileac veins
-Aneurysms usually at the more distal arts that abut where the balloon was
-Worse outcome than 50% success in William's pts, and these pts can often improve by self w time, and mortality from procedure can be 7-8% (double others) thus ppl often just watch before intervening
Balloon-Expandable Intravascular Stents
-signif improved outcomes w stents
-...
Surgery
-more prox lesions are treatable w some success..., but not distal ones...
-combined approach is best...
Course & Px:
-no SBE ppx needed unless pt has prosthetic material and then only for 6mo
-Most pt w mild-mod stenosis- stable P gradients, and often decr w time as pt grows (esp w Williams, Noonans, congen rubella)
-But, if sev multiple periph stenosis, it can be progressive w poor Px unless angioplasty/stent/surgery
-xx = RV failure, PA thrombosis, poststenotic aneurysmal diltion w pulm art hemorrhage, death as child in some pts
-Isolated periph PA stenosis is rare in adults, and often misdiagnosed as ch pulm thromboembolic dz
Imaging
[ ] Define the morph of the PV- leaflet mobility & thickness
[ ] P annulus diameter
[ ] MPA/BPA diameters
[ ] Mean & Pk gradient at PV, fr multiple views
[ ] ID additional levels of obit (sub/supra)
[ ] check for PDA, direction of Q
[ ] check for PR
[ ] check RVH, RV dilation
[ ] check RV fx
[ ] check RV systolic P based on TR jet
[ ] check TV size/morph
[ ] check degree of TR
[ ] check RA size
[ ] check for PFO/ASD & direction of shunting
[ ] check for assoc defects
Fetal Echo
-Dx well by fetal
-mild-mod PS--> Nl chamber size, and PDA w Nl antegrade Q, so you must rely on PV size, morph, flow accel
-sev/critical PS--> RV morph d/o amt of TR- if severe TR, then see RV dilation, w Nl or thinned RV wall. If no TR, then see RVH
-if critical PS--> see retrograde Q at PDA (syst to pulm)
-may progress to pulm atresia, so follow closely
-if +obstruction at PFO, then high risk for hydrous (ref 18)
-decr preload--> LV can't generate enough cardiac output
-hard to dx restrictive PFO bc one can't rely on a signify incr in the velocity to ID restriction. Thus must look for signs of impending hydrous- incr CT ratio, PC effusion, holosystolic TR, abNl Doppler vn Q
Pre-op & Pre-Cath assessment
[ ] PSLA and PSSA for PV anatomy
[ ] SCSA and R ant oblique views--> check for additional levels of obstruction
[ ] high parasternal view- see cross-sectional image of PV to see short axis (first get Ao in short axis, then rotate 10-20 degr clockwise)
[ ] check RV thickness and degree of systolic flattening to ID amt of PS
[ ] CW/PW to assess degree of PS
-***the P gradient d/o amt of Q across the valve, so if pt has RV dysfx, then SV is reduced so PS amt is underrated.
-***if pt has pulm htn, or pt has a PDA, then the P gradient will be lower, not bc of the Pvlv, but bc of higher distal P...,
-***ASD etc that will incr L to R shunting intracardiac will--> false incr in P gradient bc incr RV Q
-Bernoulli equation less reliable with long segment stenosis or multiple stenoses in series
-Peak Instantaneous Gradient (PIG) is often higher than the Peak to Peak Gradient by cath (ref 22), however, the literature supports the PIG accuracy to predict the cath derived max instantaneous gradients (ref 22-24). Ref 25-26, though, says output mean Doppler gradient is more accurate to predict cath peak to peak gradient
Intervention
-indications for Tx remain controversial
-low morbidity by cath
-Mullins--> balloon valvuloplasty if Doppler PIG is as low as 35mmHg if pt has other signs of RVH by echo/EKG (ref 30). Others use a threshold of RV systolic pressure of 55-60mmHg (NOT gradient)
-nearly all critical PS pts are treated in cath lab
-balloon use is usually 1.1-1.3 x the pulm annulus
Post-op Assessment/Long Term xx
-ref 32- no pts had mod-sev PR in cath group, vs 45% in the surgical group
-ref 33- 44% postop PR in surg group, vs 11% in cath group {?must check to see if similar pre-op xx}
-long-term follow fro PS and for PR
-ref 33- at 10yr f/u, 5.6% of pts post surge had restenosis, vs 14.1% of pts s/p balloon
-surgical long term xx (ref 34)- 37% had mod-sec PR at 22-23yr f/u, 9% had reoperation; ref 35- at mean 34yr f/u. 53% had re-op, and 75% had valve change bc of sev PR
-check for infundib stenosis postop, as studies have shown an incr in gradients immediately postop
-this is expected to decrease in short and long term
-if +residual gradient at the level of the valve, it is not likely to resolve over time.
-ref 38- Noonans pts have higher residual gradient, so some advocate surgery for PS in these pts
-ref 39- if critical PS, may undergo balloon, but some require a transannula patch
-ref 40-41- post PS balloon, the TV will increase in size
-Suicide RV- in critical PS pts, if we dilate the PVlv, then might have hyper dynamic RV with infundib RV--> decr RV CO, and pt remains canonic
-hyperdynamic xx problems usually resolve in days; xx of RV compliance takes weeks to improve
Pulmonary Regurgitation
-Mild PR common pre-op, c/s it Nl variant
-must follow post intervention
-if signify regurg--> retrograde Q at branch Pas
-hard to quantify, some look at jet size, depth into RV, vena contracta width, etc.
-spectral Doppler to check end-diastolic pressure diff bn RV and PA
-check for RV dilation fr vol OD
Subpulmonary Stenosis; Double Chamber RV
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