Double Inlet Left Ventricle (M/A)

Univentricular AV Connection (MA54)

Terminology:

= the main ventricle gets Q fr both TV and MV, or fr the common AV vlv if there's an AVC defect

-can't call it a "single" ventricle, bc in truth there is a 2nd ventricle, though small/rudimentary

-The univentricular AV connection can be 2 atria to 1 ventricle (e.g. DILV), 1 atrium to 1 ventricle (e.g. tricuspid atresia +IVS w hypoplastic RV), or an unbalanced complete AVC w a hypoplastic ventricle. (see diagram)

-Note, in true Andersonian speak, he would describe the AV connection (2 atria, each to their own ventricle, vs 1 atrium to 2 ventricles, vs 2 atria to one ventric. In the latter case, then describe if it is double inlet, or absent right or absent left connection (connection isn't the same as atresia, bc in tri atresia you can still have an AV connection in that the atretic valve is overlying the RV and you need only pop it open to establish RA-RV flow). Then if it is DILV, describe if there is a dominant LV, RV or indeterminate ventricle, and then describe if there are 2 AV valves or a common AV valve (e.g. CAVC to one ventricle).

Ventricles:

-ID ventricle type by myocardium morphology

-LV- smoother, numerous fine meshlike apical trabeculations

-RV- irregular surface w few, coarse, straight trabeculations

-infundibulum is in RV only (normally), made fr the distal bulbus cordis

-thus, even if hypoplastic, the chamber that has an infundib that--> the GA = an RV, & a chamber w GA connection w/o an infundibulum, or only exit is via VSD (no GA connection) = an LV

AV Valves:

-if there are 2 AV connections, then the one going to RV is TV by definition, and one to LV is MV by definition bc the valves follow the ventricles...

-w univentricular connection, harder to say it's a TV/MV

-With Double Inlet or Common Inlet, describe the valve sidedness instead...

-Overriding = AV valve annulus is committed to the ventric chamber, due to atrial/ventric septae malalignment. It is determined by annulus, not cords. Consider it connected to the ventricle to which >50% of the valve lies over it...

-If >75% of the annulus of a common AV vlv empties into one ventricle, then c/s it a common inlet ventricle.

-Straddling- cords and paps insert on the contralateral ventricle, thru the VSD

-often w DILV, the right sided valve straddles into the hypoplastic RV

GA Connections:

-concordance d/o the ventricle and GA type (PA fr morph RV, Ao fr morph LV)

-Can have concordance or discordance

-can have a single outlet (normal), or a double outlet

-VA connection is considered if >50% of the GA overlies the ventricle at the valve level

DILV

-Van Praagh classifies DILV as:

-I - Normally related GA (R post Ao)

-II - R Ant Ao

-III - L Ant Ao

-IV - L Post Ao (not seen)

-DORV (in setting of DILV) is usually fr a rudimentary RV. If pulm atresia or truncus, can have single outlet

-AV Valve xx- atresia, stenosis, hypoplasia, straddling, overriding vlv

-with an atretic valve, c/s it DILV if the valve's plate is >50% over the LV

-DILV pts often have Pulm outflow tract obstruction, regardless of VA concordance

-usually bc of post deviation of infundib septum, but also bc of R AV vlv anomalous attachments or herniation of valvar tissue into the pulm outflow tract. Often have thick/bicuspid pulm valve.

-DILV can have subAo obstruction, usually if +VA discordance, fr the VSD (bulboventricular foramen type), or bc of sev ventric hypertrophy of muscle bundles in the hypoplastic RV

-increased in pts w R AV vl atresia, or pt w prior PA band bc the PA band--> incr ventric hypertrophy and then obstruction in pt w a mild restriction at the VSD. Present w CoAo as infant.

-Conduction abNlies- like pts w ccTGA, occur

-if DILV, the connecting AV nd is always ant-lat, at the acute margin of the R AV vlv orifice, and then perfs the annulus of the R AV vlv to enter the main LV chamber. The nonbranching bundle then courses along the R sided rim of the VSD (outlet foramen), to get to each trabecular septum.

-The subsequent course of the bundles d/p the ventric morphology:

-Hypoplastic RV on R side: R margin of VSD is next to the ant-lat node, so the nonbranching bundle passes down directly onto the R rim of the VSD, and then goes down twd the crest of the trabec septum, along the LV aspect of the ventric septum and then branches beneath the septal crest.

-Hyopoplastic RV on L side: the right rim of the VSD is now also the ant margin of the defect, and is separated from the ant-lat node by the posterior GA, so the nonbranching bundle thus has to go more anterior to the posterior GA valve annulus, to get to the septum.

-If the RV is on L side, the conduction bundle runs above the VSD when viewed fr the main ventric chamber. If the RV is on R side, the conduction bundle runs beneath the VSD when viewed fr the main ventric chamber.

DILV WITH NORMALLY RELATED GAs (A-I)

-hypoplastic subpulm RV and Nly related GAs

-rare, 15% of van praagh's pts

-the VSD = the primitive bulboventricular foramen

-VSD often --> signif subpulm obstruction--> more balanced obstruction, w some hypoxia and low PA P

DILV WITH R SIDED HYPOPLASTIC SUBAORTIC RV (A-II)

-similar to ccTGA w severe override and straddling of the R AV valve to the morph LV valve, and associated hypoplastic morph RV.

-25% of van praagh's single ventricle cases

-VA discordance--> Ao is usually R anterior

-+/-SubAo and pulmonary stenosis

-Conduction tissue enters trabec septum fr an ant-lat node

-nonbranching bundle goes along R rim of VSD and then divides over the crest of the ventric septum

DILV WITH L SIDED SUBAORTIC HYPOPLASTIC RV (A-III)

-most common type of univentric connection

-38% of vanPraag series

-?similar to ccTGA but the left sided AV valve (~tricuspid vlv) got committed to right sided LV via straddling/overriding

-see different associated AV vlv, semilunar vlv, outflow tract xx, including subAo obstruction (must check for it before Fontan...)

-signif ventric hypertrophy increases operative risk bc of ventric diastolic filling xx and elevated LV EDP

DIRV

-rare

-near absence of LV

-both AV valves have >75% of total AV vlv orifice to morph RV

-the LV is usually post and slightly to the L of the morph RV

-sometimes (if L looped), this is reversed and LV is ant and R of RV

-usually DORV

DOUBLE INLET VENTRICLE OF MIXED MORPHOLOGY

-double inlet, without an outlet chamber

-rare

-some just call this a very large VSD

DOUBLE INLET VENTRICLE WITH INDETERMINATE OR UNDIFFERENTIATED MORPHOLOGY

-may look like DILV or DIRV...

-Dx if u can't clearly decide if it is an RV or LV

-...

SINGLE INLET VENTRICLE

-single AV connection to a single connection (as oppose to CAVC to 2 ventricles)

-occurs with mitral atresia or tricuspid atresia

-AV concordance or AV discordance

-like DILV the hypoplastic ventricle often functions as the outlet chamber

-conduction system d/o AV connection status-

-if AV concordance, w absent R AV connection/tri atresia, then it is like w an isolated VSD

-if AV discordance, the Nl AV nd can't make contact with the ventric myocardium, so the ant node is the connection nd, and the nonbranching bundle encircles the ant side of the pulm valve to get to the right rim of the VSD where it branches.

COMMON INLET VENTRICLE

-both atria connect to a single ventricle via a common AV valve

-assoc w an AV septal defect

-usually w situs ambiguous, espec asplenia, w common atrium, common AV valve, and common ventricle.

...

Si/Sx

-Sx d/o if there is Qp obstruction

-No Qp obstruction--> Sx like a large L-->R VSD shunt

-sev CHF, tachypnea/tachycardia/diaphroesis/hepatosplenomegaly/FTT by 3mo

-if early CHF (<1mo), likely bc of assoc xx- AV vlv abNly, Ao outflow obst, CoAo

(bc PVR drop delay, so CHF fr Qp would be delayed...)

-Might not be cyanotic bc of incr Qp

-Some have favorable streaming- DILV w subAo RV to the Left, so systemic venous bld Q goes to PA and pulm vns Q to Ao...

-If R sided subAo RV and some R AV vlv straddling, might have UNfavorable streaming w Q like a TGA--> much hypoxemia/cyanosis

-May have a soft SEM bc of Qp flow or VSD flow to the hypoplastic RV

-May have a diastolic AV valve inflow murmur bc of large Qp

-May p/w pulm congestion/pna

-If +Qp obstruction--> hypoxemia/cyanosis early as a neonate.

-+systolic thrill if pulm/subAo outflow obst

-+/-SEM and Single S2

-may hear pulm valve close

-if pulm atresia--> no murmur or soft cont murmur may be heard bc of PDA or syst pulm collats.

-If long standing phtn, S2 may be single/accentuated

-+/-Diastolic murmur of pulm regurg

-sev pulm vasc obst dz if >2yo

ECG:

-...

Echo:

-Dx on AP4C looking at the crux of the heart- see AV connections and commitment of the AV valves

-check for gradients at outflow tracts/GAs

...

CXR:

-vary based on anatomy...

MRI- valuable for extracardiac abnlies of venous connections, and of Ao arch, and PAs...

Cath:

-Goals:

-location/integrity of syst/pulm venous connections

-presences/adequacy of atrial communication

-AV valve fx

-ventric morph/fx

-size, integrity, distrib and arteriolar resistance of pulm vasc bed

-GA connections to ventricles

-location/integrity of Ao and Ao arch

Venous Connections

-check hepatic/IVC connections

-innominate vein drainage thru RSVC, presence of LSVC

-if LSVC, check size, connection to R/LA

-if considering ligating LSVC, then must 1st balloon occlude each VC to check the rise in venous pressure distal to the balloon. If SVC P incr >20mmHg, c/s inadequate collateral venous Q to allow you to safely ligate the LSVC...

-check the pulm vein connections via cath, check pulm vn P, f/o APVR

-if single inlet or atretic AV connection--> check ASD adequacy by echo/doppler/cath, c/s atrial septost.

AV and VA Connections

-use Cine on cath to check AV valve commitment, annular size, leaflet abNlies, and assess presence/severity of valvular regurg

-sev AV valvular regurg--> ventric volume OD and incr filling P

-important to know hemodynamics before doing a Fontan...

-check gradients at outflow/GAs...

-resting subAo P grad >40mmHg

Ventricular Morph & Fx

-check angiograms/cine...

Pulm Circulation

-check central PA size, r/o stenosis at MPA/distal PAs

-selective PA injections in AP/lat views...

-check for pulm AV fistulae (espec if Glenn pt)

Systemic Circulation

-check arch anatomy, syst to pulm shunts, PDA, syst pulm collaterals

Tx:

-need palliation to protect pulm bed and/or myocardium

-PA band if univentric AV connection without PS

-<6mo if CHF sx to prevent PVD

-if signif subAo obstruction--> c/s Ao-Pulm Window and endoluminal banding operation to prevent ventric hypertrophy and to protect pulm vasculature

-BT Shunt to prevent signif cyanosis/polycythemia

-Then Glenn shunt by 4-6mo (better than BT shunt bc it doesn't increase ventric volume)

-classic Glenn xx- AV fistulae..., usually after 5yrs; also lose RPA and LPA confluence, distort or stenose the SVC or RPA, cause RPA thrombosis, abNl R pulm Q, failure of RPA to dvp Nly...,

-Modified Glenn --> establish bidirectional cavopulm anastomosis, whereby the cardiac end of the SVC is attached to RPA but leaves PA confluent and --> less pulm art tree distortion...

-Eventually Glenn isnt enough bc of incr cyanosis over the years *by 203yrs) (bc relatively decr cerebral Q)

-if PAs stay hypoplastic, then may need more syst to pulm shunt to relevie the cyanosis and promote growth of pulm vasc bed

-3 Options for long term palliation for pt w univentricular AV connection:

-ventricular septation

-modified Fontan

-cardiac transplantation

PICTURES