Pulmonary Stenosis (M/A)

Pulmonary Stenosis (MA40)

-usually bc of pulm valve stenosis, but can be intracavitary or supravalvar, and may include MPA or branch PA

-PS occurs in 25-30% of pts w CHD

ISOLATED VALVAR PULMONARY STENOSIS

-Occurs in 80-90% of pts w RVOTO

-occurs in 8-10% of CHD

Path:

-not well understood

-Distal Bulbus Cordis maldevelopment (?); ? if fetal endocarditis, vs genetics...?

-Valve is conical or dome shaped, with 2-4 raphes, but no separation on valve leaflets

-Less often, the leaflets are thick with fusion at one or more commisure

-Pulmonary Valve Dysplasia- separate form seen in 10-20% of them: very thick cusps made of disorganized myxomatous tissue, without much fusion. Hypoplastic annulus. Most often seen w Noonan.

-2y RV and PA changes can --> pulm vlv obstruction

-RVH esp at infundibulum --> dynamic subvalvar obstruction.

-Small subendocardial infarcts seen at autopsy in the RV free wall and paps if sev PS

- +/- Thick TV and cords, +/- TR

- +/- Thick/dilated RA bc incr P to fill hypertrophied RV

- +/- Poststenotic dilation at PA trunk, which can extend to LPA, but often much worse w PV Dysplasia

-can occur bc of high velocity jet fr the small vlv orifice

Physiology:

-PS--> incr RV P --> RVH via:

-fetus/neonate (animal studies): incr AL --> incr # muscle cells and capillaries

-adult models: incr AL--> hypertrophy of existing fibers, no change in # caps.

-Thus, neonates better able to handle the incr RVP

-Incr RVH --> more able to keep SV against the AL...

-With a fixed PS size, as pt grows, the degree of relative obstruction worsens... and RV will dilate and eventually may fail.

-TR will worsen this in pts w sev PS

-RV failure as infant if sev PS obstr, and as RV CO drops, O2 extraction must increase for VO2, and any incr in VO2 (exercise) can --> cyanosis...

-If +PFO/ASD, then central cyanosis seen bc R-->L shunt when RA P > LA P.

-Incr RVH and decr RV Compliance or myocardial failure (and then RV dilation) --> central cyanosis even if well compensated.

-Critical PS = in utero, if PS bad enough to --> decr RV output, then the atrial shunting R-->L is >Nl

-RV often hypOplastic bc sev RVH and bc of decr Q thru RV

--> cyanosis and RV w suprasystemic/systemic RVP at birth. Even if you relieve the PS, the R-->L shunt will cont for months until RVH improves and RV size increases...

Sx/Si:

-Most ASx, and Dx made with murmur

-Sx start usually after childhood

-DOE, tired bc RV cant respond to exercise

-Eventual RV failure s Tx

-Cyanosis is usually minimal unless large ASD shunt...

-W mod-sev PS, can --> CP, syncope, sudden death w exercise (? bc decr RV CO causing ischemia/arrhythmias)

-Nl growth/dvp regardless of PS severity

-If pt is squatting, c/s TOF bc really rare w PS

-If critical PS, then --> cyanosis at birth and can be life threatening. RV cavity relatively hypoplastic but ASD/PFO usually big enough for CO so RV doesn't fail.

-Failure can start if signif TR or if ASD not big enough as pt grows...

-Auscultations: Nl S1, w pulm ejection click if mild-mod = doming PV reaches open position. Earlier click = more sev stenosis until it merges w S1..., Click intensity varies w respiration (incr w Insp).

-SEM at LUSB w rad to back and maybe to entire precordium/neck. Intensity incr w degree of PS- mod-sev is 4 or more, but if sev PS can be soft bc low CO.

-Murmur length d/p duration of RV ejection, which d/o severity of PS.

-Murmur peaks later if more sev obstruction

-Soft, early diast murmur if mild PR

-Nl a wave thus no JVD/Nl pulsation if mild PS, but they both can incr (w pulsatile liver) twd sev PS

-Prominent RV syst impulse and syst thrill if sev PS

-thrill at 2-3rd IS +/- suprasternal notch, but can be absent w heart failure w low CO or infant

-S2 split- amt incr w sev PS, anf fixed if fixed SV fr sev PS

-P2 may be louder w pulmonary art trunk dilation

-S4 at LLSB if sev PS

-If +S3, c/s ASD

-In older pt w sev PS, may have only soft murmur bc decr CO..., may have holosyst murmur fr TR, PDA heard at mid to upper sternal border

ECG:

-Up to 1/2 have Nl ECG, often see only slight RAD

-Often see RV conduction delay

-Mod PS--> 90% abNl ECG: RAD, R:S Vi >4:1 & R precordial T waves upright in 1/2

-Sev PS--> RAD w QRS axis >110 in frontal leads; pure R, Rs, or QR at right precordials, w R>20mm; R:S V6 <1, T waves up or inverted at R precordials, P waves tall and pk'd in II and R precordials (RAE)

-In pt 2-20yo, if pure R in V4R or V1, then (R wave height) x5 = RVP in mmHg

CXR:

-prominent MPA bc poststenotic dilation (80-90% pts but often not in infants ) +/- LPA too

-Rounded, down pointing apex

-RA prominent, esp if TR or ASD

-~always L Ao Arch

-Mild-Mod stenosis--> usually Nl heart size and pulm vasculature; w sev only see CM if RV failure, along w decr pulm vasculature

Echo:

-PSSA and high pSSA and PSLA, and SCSagital good to check for PS

-Thickened leaflets, restricted systolic motion w domeing =inward curving of leaflet tips

-+/- poststenotic PA dilation, RVH, RV contractility changes

-Check for TR

-Check for dynamic sub PS- can be hard to check severity if valvar stenosis is > mild

-Check for dysplastic pulmonary valves

-thick, immobile leaflets without doming

-hypoplastic PV annulus, and supra annular narrowing of prox MPA common post stneotic dilation)

-Check P grad on doppler

-Bernoulli --> P =4V²

-Must account for velocity below the pulmonary valve as well if there's signif sub-PS as well

-Ensure echo beam || to MPA trunk/Q

-If +TR, then use Doppler for delta P bn RA and RV; P_RV= P_RA + P grad...

-P grad correlates well with DOpler, but the Doppler peak instantaneous P exceeds teh Pk to Pk grad measured at cath by a small amount. In Pulm Valve Stenosis, it is usually insignificant, so no cath needed.

Cath:

-usually just therapeutic because of echo

-Balloon Pulmonary Valvuloplasty now used instead of surgery usually

-Hemodynamics

-Check RV P vs syst art P

-Check P grad across Pulm vlv.

-Resting RV P >30-35mmHg & Delta P at valve >10mmHg = AbNl

-Use end hole cath, with a pullback fr MPA to RV to find location/severity of PS

-If there's also infundibular stenosis, then the P curve is usually a triangle with a fall in the late Sys P because of the progressively narrowing RVOT during contraction

-RVEDP may be Nl, but usually is high if sev obstruction or w RV failure

-RA P is Nl if mild-mod PS, but high if sev PS (w tall a waves in RA)

-If mild PS, then PAP is Nl, but if sev PS, then PAP is low. It is especially low just after the valve than further down the PS bc of Bernoulli effect (increase Q across the stenotic valve--> more of the total energy expressed as kinetic energy, so the P drops to maint total energy constant. As the velocity of Q decreases downstream, then P can recover...) [Think: Q=vA, with Q constant and A smaller, so v increases, and because energy is constant, and Bernoulli says the energy is related to kinetic +pressure (potential) + gravity, then w incr velocity (thus incr kinetic E, potential E (pressure) drops...

-Gradient Classification (usually based on RVP and delta P, if RV CO Nl)

-Mild PS: RVP <1/2 LVP or delta P at valve <35-40

-Mod PS: RVP >1/2, >75% LVP or delta P at valve >40

-Sev PS: RVP >75% LVP, or grad >60

-Exercise--> incr P grad at the stenotic Pulm Valve, because incr in HR (rate of contraction) --> incr Q velocity at the obstruction (see Bernoulli discussion above- PAP P drops)

-Much incr in HR can --> shorten diast filling time in an already hypertrophied/stiff RV --> decr CO and thus decr LV CO--> hypotension w severe tachycardia....

-RVEDP which is Nl at rest will incr w exercise bc of the above (stiff RV...)

-Angio-

-Great for Dx/Tx

-Check anatomy w AP angled cephalad + lat view

--> mildly thick PV leaflets w dome in systole then Nl position w diastole

-Narrow contrast Jet at valve , usually along ant-sup margin of the MPA --> post stenotic dilation

-Pulm Valve Annulus- usually Nl size, but if sev can be hypoplastic

-RV cavity usually Nl size, but can be hypoplastic if critical PS, or dilated w CHF

-Thicker RV walls w prominent trabeculations

-Usually Nl RV fx

-W dysplastic pulm vlvs--> much thicker valves, w relatively little movement (little excursion), and hypoplastic annulus, and proximal MPA hypoplasia,

-often see tethered valve leaflets to the MPA wall at the ST jct.

-No poststenotic dilation of MPA

-RPA originates from MPA more proximal than Nl.

DDx:

-PS+IVS able to make Dx on ausc + ECG/CXR

-DDx:

-DDx mild PS fr

-idiopathic MPA dilation

-ASD

-MVP

-straight back syndrome

-mild AS

-innocent murmur

-DDx mod-sev PS fr

-VSD +/- assoc PS

-mod AS

-if +cyanosis w sev PS, must r/o TOF and PA+IVS

-also c/s Ebstein's in neonate (can look like sev PS)

Systemic Disease + PS:

-Noonan's - 1/2 have CHD - PS w Pulm Valve Dysplasia is #1 among these CHD

- 1/4 have LV HCM +/- PS

- Exam often doesn't show how sev the PS is - often absent ejection clock; soft short murmur

despite sev PS, and ECG shows superior axis deviation even if no CM

-Intracardiac Tumors or Extrinsic Lesions compressing heart - rare cause of PS

-Echo/MRI --> Dx

-Leopard Syndrome (Multiple Lentigines synd)- assoc w Pulm valve/annulus stenosis.

-NF, glyc storage dz, gout rare--> RVOTO

-Carcinoid dz of the bowel may --> endocard fibroelastosis of RV w T and t vlv involvement--> stenosis

Tx:

Balloon Valvuloplasty-

-Was the start of peds balloon angio in early 80s

-end hole cath into distal LPA

-balloon that is 20-40% larger than the angio measured pulm valve annulus, and position over guideqire w valve at midpt

-Inflate, w waist seen at stenotic valve, then disappear at full inflation

-Larger pt w annulus >20mmHg, then use double balloon technique w 2 balloons

-Then, do a careful pullback w end hole cath to check residual stenosis

-you may see a gradient at infundibulum that was prev masked by the valvar PS. This is a dynamic RVOTO that should resolve w time as RVH resolves.

-Pt w critical PS- use PGE before cath for PDA

-Can place the wire through the PDA and then hook it into desc Ao so it is more stable.

-Balloon Outcome:

-short/intermed - great: One study: Good outcome = <36mmHg gradient on Doppler and no need to repeat procedure - seen in 77% of cases, 85% of those w typical (e.g. not dysplastic) valve morph. But, 65% if pts w dyplastic valve had a not Good outcome.

-Smaller valve annulus, higher residual gradient, earlier year of initial valvuloplasty, and smaller balloon:annulus ratio predicted worse outcome. (balloon:annulus ratio of >1 prob -->better Px, but can --> incr risk of late severe PI)

-Long Term outcome- smaller series: at 12yrs w avg balloon:annulus 1.3, still good outcome w/o reintervention ) 1yr- 90%, 5- 83%, 10- 83%, 15yr- 77%. Most of the patients needing reintervention during this time had dysplastic valves, and 2 needed surgery for sev TR

-All had NYHA class I and no arrhythmias (n=134 pts)

-It makes sense that dysplastic valves have worse Px bc less defined commisural fusion, and more myxomatous valves. Still no good predictor of poor outcome for these valves.

-Neonates w Critical PS: Px worse than noncritical pts, regardless of valve morph

-at avg 3-4yrs post-op, success varied, initially bc of procedural failure, but now less so. If they are able to dilate it, then good gradient reduction achieved in 90% of pts, but 5-10% of these pts still didnt have enough fwd Q thru Pulm vlv to maint sats bc of the hypertrophic, noncompliant and sometimes hypoplastic valves...

-If they failed the valvuloplasty, you can cont PGE for a few weeks and periodically turn it off to check whether constriction of the DA will allow for sats >70%.

-Place a BTS/Sano if you fail to wean off PGE by 3 weeks old

-May need to make balloon atrial septostomy for CO

-Many children w initial critical PS get improved cyanosis as RVH resolves and gets more compliant after Balloon valvuloplasty, even if they have cyanosis postop initially.

-Consider PDA stent instead of BTS/Sano if needed (first used early 1990s)

-But, PDA stents tend to narrow over a few months, but it gives enough time for RH growth and better RV compliance.

-It is important to have fwd Qp thru the valve to promote RV growth and decr RVH

-5-15% of pt w critical PS eventually need surgery for valvar stenosis or subvalvar obstruction

-These kids tend to have smaller TV, PV, and RV (but not great studies bc small n)

-Some need single ventricle repair bc RV hyoplasia too severe

-Major Complications:

-Very low, but higher in infant/kid than adult

-Procedureal Mortality 0.2% - laceration of IVC during balloon withdrawal, tearing Pulm valve annulus during inflation (5 day old and 12mo respectively)

-vein thrombosis (1.3%), vein tears, arrhythmias

-Neonates: 3% mortality- vn injury, myocardial dissection, NEC

-Neonatal Morbidity: 10%- RVOT perf w wire, +/-tamponade, stroke, sz, NEC< endocarditis, septic shock, ductus closing abruptly despite PGE--> urgent AP shunt.

-Pulmonary Insufficiency

-Most pt have some PI

-Mod PI- 5-24% immed to intermed f/u, but longer you follow the more PI you see, esp if early repair. 22% had mod and 2% sev PI at about 1yr postop

-By 12yrs postop, 40% had mod PI, 17% sev PI (sev = reversal PA Q and nonrestrictive regurg at Pulm vlv by doppler).

-Pt w sev PI had enlarged RV

-Only smaller BSA at initial procedure as neonate correlated w worse PI later

-74% of pts who had valvuloplasty as neonate had mod-sev PS at f/u, as opposed to 44% fr other pts. One study showed a larger balloon: annulus and worse PS and younger age preop had worse PI postop

-BUT, compared to surgical valvotomy, valvuloplasty --> less PI (but f/u time for cath is shorter than for surg).

-Signif PI w/o other dz can be well tolerated for a long time, but exercise capacity can drop w mod induced PI w exercise

-Some pts needed valve replacement, all were <2mo at the time of the cath. These kids had avg ballloon:annulus of 1.44 (vs 1.08 avg for all kids studied)==> thus don't be too agressive w the balloond dilation, use ratio of ~1.2, even if it means repeat balloon dilation later.

Surgical Valvotomy

-Only for pt w dysplastic pulm valves that failed valvuloplasty or w multiple levels of fixed obstrcn.

-Via either closed or open technique thru MPA

-Often immed postop gradient continues, bc of dynamic narrowing of hypertrophied infundibulum (Same like post cath)

-See gradient reduction in the first 24hrs postop and then less quickly after that as RVH resolves over months.

-Propranolol- may differentiate dynamic fr fixed obstuction

-xx- fatal RV failure immed postop

-Dysplastic valves

-Simple valvotomy not enough. Must do partial/total removal of pulm valve, +/- transannular patch to enlarge the hypoplastic annulus and MPA. Often > at least mod pI, but well tolerated initialy. Long term can have xx

-Surgical Outcome

-Long term- good Px, restenosis uncommon (96% success at 10yrs)

-Post op PI 57-90%- mod to sev in 28% by echo

-97% of pts who survived at 25yr had NYHA class I, in another study it was 82%

-mildly decr exercise tolerance

-One study: 33yr f/u: 53% needed reintervention, usually to replace PV bc of free PI, w signif number of these pts 25yrs postop or more (50% no intervention at 40yo, 80% needed surgby 45yo) w those that didnt get surg at 45yo having mod-sev PI in 70% of them

-Arrhythmia risk increases w time- 38% atrial and 6% ventricular at long term f/u

-Survival- good outome at 33yrs (96%) w death in 2pts- fr a-fib untreated

Indications for Surgical or Cath Tx:

-Cath 1st at any age and morphology (usually),

-Critical PS in neonate--> immed Tx

-If ASx w sev obstruction, treat semielectively soon after Dx; little benefit to watch/wait for growth given today's low profile balloons. And waiting can be harmful as infundibulum hypertrophies making it harder to do procedure, and increasing RVH postop.

-If moderate obstruction, then do it if RVP >50% systemic

-No intervention if mild PS, w no sports restriction needed

-No SBE ppx needed w PS

Assessing Severity, Course, Px:

-Sx don't reflect course bc usually ASx unless sev/critical PS

-Mild PS: grad <30-35mmHg at valve, RV P <1/2 systemic

-Benign course, no Tx needed; Nl response to exercise

-No deaths at 4, 8 yr f/u

-of pts w grad <40 at Dx, only 3/261 pts had grad >60 at 4,8yr f/u

-of pts w grad <25, none had incr grad

-EXCEPT, in young infant w mild PS (grad <40mmHg)- in pt <1mo, 29% progressed to mod-sev PS, w 1/2 of these by 6mo. This may be in part bc decr PVR makes it seem worse, but also bc of anatomy.

-Mod PS:

-Controversial - may worsen during pds of rapid growth

-Grad 50-79 - great survival after 20 yrs regardless of med/surg mgt, but most had surgery by 20yrs later. In the same study, 20% of pts w grad 25-49 needed surgery.

-Even in ASx pts w mod PS, they had subNl CO w exercise, and abNl incr RVEDP w exercise, esp in adults, so there's prob both syst and diast xx bc of the longstanding moderate pulm outflow obstr.

-Current Recs: balloon valvuloplasty if Doppler grad >40mmHg

-Sev PS:

-incr sev obst w time in most pts, maybe bc child grows more than the valve...

-If correction is delayed beyond childhood there can be irreversible changes in fx, seen on adult pre and post op exercise tests.

-Lower SV at rest and w exercise, and postop the SV and RVEDP improve within 1yr, but not if the correction was done in older pts (permanent changes- myocardial fibrosis...)

-Other morbidity (bact endocarditis) w Pvlv stenosis very low, so no SBE ppx rec'd, unless pt gets a prosthetic valve.

Indications for Pulm Valve Replacement for PI after PS Relief:

-Controversial

-Pulm Valve replacement data mostly from TOF pts

-limited data, esp p 40yo

-Current criteria:

-+Sx *decr exercise tol/NYHA class), RH failure

-progressive RV enlargement, often w incr TR bc annular dil'n

-prorgressive atrial/ventric arrhythmias

-Ppl argue against ppx valve exchange bc there isn't a good longstanding prosthetic valve, so you will have to reintervene in the future, so ppl wait as long a possible, but no to the pt that there's irreversible RV injury

-Surgical PV change- needs CP bypass, use homograft, xenograft, pericardial, mechanical valves - all get Ca'ion or intimal proliferation --> PS/PI.

-Melody valve- perQ- bovine jugular veinous valve- 1st done in 2000

-Surgical PV valve change- not yet shown to improve RV dynamics/fx, and no long term survival data

PRIMARY INFUNDIBULAR STENOSIS

-Rare - 5% of RVOTO

-2 Types:

-Obstructive fibrous band at jct of RV cavity and the prox infundib (looks like double chambered RV)

-Narrowed infundibulum due to fibromuscular thickening, may extend fr imed below pulm valve to prox infundibulum.

-Sx/Si are same as that for RVOTO due to anomalous muscle bundles, as is surgical considerations.

RV OBSTRUCTION DUE TO ANOMALOUS MUSCLE BUNDLES

-aka DOUBLE CHAMBERED RV

-aberrant, hypertrophied muscle band divides RV cavity into a proximal high P chamber and a distal low P chamber.

Path:

-anomalous, hypertrophied mulsce bundles make a pyramid shaped mass running bn IVS inferior to the insertion of the septal leaflet of TV to the ant wall of RV.

-Usually 2 bundles

-Ventral bundle- attaches to RV wall next to septum

-Dorsal bundle- attaches to base of ant pap muscle, larger

-RV cavity divided into -Prox chamber- made of sinus part of RV

-Distal chamber- made of infundibulum

-The bundle orientation is diff than that of moderateor band, whose septal attchmt is at the apical 1/3 of ventric septum (while these bundles' septal attachments are near the base, by TV ring), and the mod. band lies next to septum, so not obstructing the cavity.

-? etiology of the bundles, ?trabec myocardial growth early on, or arrested incorp. of primitive bulbus cordis into RV body- and thus assoc w VSDs bc if the bulboventric jct didnt fuse completely w endocard cushions (which usually closes the sup part of IVS)

-assoc VSD's are usually perimembranous

Physiology:

-obstructs RV, can increase with time

-may be unobstructive as neonate but later on become obstructive

-during systole, the diam of the channels the blood must go thru gets smaller...

--> high P in prox chamber

Sx/Si:

-Similar Sx as isolated pulm valve stenosis.

-If +VSD, the main Sx may be fr the VSD

-Ausc: loud pansyst cresc-decresc murmur, +/-thrill (common), @LSB - can't Dx fr isolated valvar PS, except no click, and pulm valve closure may not be as delayed or as soft as expected w valvar PS

-CXR: similar to other RVOTO, unless signif VSD

-ECG: RVH usually, may show diminished terminal RV forces

-Upright T waves in V3R was the only finding of RVH in 40% pts

-Echo: Dx well, see best in subcostal or parasternal, check amt of narrowing w 2D, Doppler for obstructn

-check VSD; may also see abNl pulm vlv fluttering

-Cath: sometimes needed to confirm Dx

-check P gradient thru RV- high P initially, low P distally (usually = to PA unless +assoc vlvr PS)

-Angio: best tool for accurate Dx of lesion, always check if signif intraventric P grad seen w AP/lat filling defects in RV, below crista supraventricularis; also check LV angio to see if assoc VSD/subAo AS

-MRI: good for Dx...

Tx:

-Surgical Tx

-see a dimple in the RV surface (usually smooth) = +obstruction usually - seen usually at ant intraventric groove, midway bn base and apex

-usually do NOT need RV ventriculotomy to see the bundle. Instead go thru TV, also check for VSD...

Px:

-Progressive dz w gradual incr severity of obst; as it gets worse the assoc VSD will get smaller and may close on its own

-Repaired- 20yo only mild residual sequelae- mild RVOTO, insignif residual VSD, TR, or Ao vlv regurg, w/o need to reoperate

PERIPHERAL PULMONARY ARTERY STENOSIS WITH INTACT VENTRICULAR SEPTUM

-assoc CHD: valvar PS, VSD, TOF

-Often part of a congenital syndrome- congen rubella- assoc w pDA and ASD; Williams Syndrome- supravalvar AS + multiple periph PA stenosis + mental retardation + abNl facies; Noonan syndrome, Alagille synd, cutis laxa, Ehlers Danlos, Silver Russell synd all assoc w PPS.

Embryo/Path:

-PA and branches develop from 3 parts:

-Prox MPA just above semilunar vlv <== Bulbus Cordis

-MPA trunk <== Common Truncus Arteriosus

-Prox RPA and LPA <== 6th Branchial Arches

-Distal part of R 6th arch disappears, while the Distal part of L 6th arch --> DA and then LA

-Periph part of pulmonary art branches <== postbranchial pulmonary vascular plexus, close in relation to the lung buds

-?pathogenesis

-if +intracardiac CHD, likely developmental xx

-Teratogens can --> ng dvp of PA tree--> atresia/hypoplasia/stenosis

-Rubella--> interfere w Nl elastic tissue formation

-Branch stenosis seen w DA closure, esp in cyanotic heart disease

-Some Genetic syndromes are assoc w isolated periph PA stenosis

-chrm 7del--> abNl elastin synth in WIlliams

-chrm 20del--> Alagille synd, ? mech

-chrom 12 mut--> Noonan's

-Gay Classification:

-MPA trunk or R & L PA stenosis

-Bifurcation of PA extending into both branches stenosis

-Multiple peripheral stenoses

-Combo of MPA and periph stenosis

-if localized stenosis, usually see poststenotic dilation, but less so if it is a longer area of stenosis.

-prestenotic dilation at MPA is NOT common

Physiology:

-incr RVP, incr PAP prox to stenosis

--> lmit volume capcity of pulm trunk prox to obstruction

-if sev obst--> prolonged RV ejection and PA trunk proximal to the obstruction is the same as that of the RV, and pulm valve remains open as long as there is a systolic P grad bn RV and the distal pulm art..., Thus, P2 is delayed even though systolic P is high in the PA.

-Pressure tracing- at PA prox to stenosis, looks like RV w high syst and low diast P.

-If there's severe periph pulm stenosis at many small branches, then Pulm valve closes early (at A2), and when the stenosis is unilateral and there's no L to R shunt, then the RV P is normal, because the other lung's vasculature/PA can accommodate the high P in the affected lung.

-Flow to the stenotic side will be lower than Nl, so they delta Psystole underestimates the severity of obstruction, but the diastolic pressure diff bn MPA and the stenotic branch is proportional to the obstruction severity...

Sx/Si:

-ASx w mild-mod bilat, or unilat stenosis

-DOE, tire easily, RH failure sx w sev obstruction

-Ausc: DDx PA stenosis fr other RV obstructions:

-S1 Nl

-No ejection click

-S2 Nly split and of Nl to slightly incr intensity

-+SEM at LUSB w transmission to axilla/back

-+/- continuous murmur = diastolic gradient across the obstruction is significant

-if multiple periph PA stenoses, then S2 at LUSB may be loud enough to c/s phtn

-+/- soft, blowing syst/cont murmur at both lung fields/back (DDx phtn)

-ECG:

-Nl if mild; RVH if mod-severe

-LAD common in pt w Noonan or rubella syndrome and PPS

-CXR:

-usually Nl, only w sev unilat stenosis is there a diff in lung fields

-if sev bilat stenosis, then see RA and RV enlarge.

-MRI- good to detail pulm art anatomy, better than echo

-Radionuclide lung perfusion scans- good to quantify flow to each lung before surgery

-Echo:

-see proximal PA anatomy well, but not distal

-PSSA and Suprasternal views

-Doppler... but cant check accurate P grad

-check 2y signs- RVH, TR, RA/RV enlarge...

-Cath:

-Need Cath to confirm Dx and determine severity/anatomy

-P tracing w withdrawal from distal branches

-P grad of >10mmHg is abNl if there is no increased Qp

-If unilateral stenosis, then P grad at site of obstruction is seen, but prox PA will be Nl, and the grad measured may be an underestimate bc Q preferentially goes to other lung.

-May have a physiologic (Nl) grad of >10mmHg in young infants, espec premies, bn the branches and the main trunk, bc of a size discrepancy bn the two...

-Large cath in small vessel can --> artifactually high grad

-Bilat PA stenosis--> P tracing prox to the obstruction has characteristic features

-Systolic part of tracing is identical to RV

-Dicrotic notch is very low w a slow descent, followed by a low P diastole, similar to that distal to the obstruction

-Pulse P is wide and increases w severity of obstruction

-These are bc the prox PA becomes an extension of the RVOT, and wall of pulm trunk is thick and fibrotic w reduced elasticity.

-As long as PAP distal to the obstruction is lower than the RVP, the Pulm valve will stay open. The valve closes w early phase of isometric relaxation of teh ventricle, w a sudden increase in volume capcity of the pulm trunk, and thus a falling P and formation of the dicrotic notch (thus it islow and w slow descent). The slow descent of the diast P is due to the distal obstruction and impaired elastic recoil of MPA trunk. If +valvar stenosis, then the severity of the periph PA stenosis can be hard to determine by P measurements (must rely on angios).