Cor triatriatum

Question 1

CTD: embryology

Answer 1

• Persistence of R sinus venosus valve

Question 2

CTD: gross examination

Answer 2

• Additional, accessory right atrial chamber
  o Separated from the true atrium by a membrane of fibromuscular tissue
   Divide RA in cranial and caudal chamber
   Upper/proximal chamber: connect CaVC and CS
• Variation reported w/ membrane more caudal: can obstruct CaVC flow
   Lower/distal chamber: connect w/ TV
  o Collect venous drainage
• Dilation of venous chambers and entering veins → obstructive lesion

Question 3

CTD: Pathophys

Answer 3

• Restrict venous return into R side of heart
  o Intra atrial membrane ↑ resistance to flow
• ↑ pressure in proximal chamber → obstruct CaVC → hepatic veins
  o +/- coronary sinus flow

Question 4

What is Budd Chiari like syndrome

Answer 4

obstruction of RA/CaVC/hepatic veins
* RA tumor
* Compression/invasion of CaVC
* CaVC thrombosis
* Veno-occlusive disease of hepatic veins

Question 5

CTD: signalment

Answer 5

o Reported in cats
o Uncommon in dogs
 Usually young dogs, present with ascites

Question 6

CTD: PE

Answer 6

o No murmur
o No jugular vein distension
o R sided CHF: ascites only
 Will form pleural effusion only if CrVC is associated w/ proximal obstructed chamber

Question 7

CTD: ECG

Answer 7

• Usually normal
• RAE: tall P waves in lead II

Question 8

CTD: CTX

Answer 8

• Enlarged CaVC
• Normal cardiac silhouette or cardiomegaly possible

Question 9

CTD: echo 2D

Answer 9

o RA is divided in 2 chambers by thin, echobright linear membrane
 Location of membrane can vary
 Cranial chamber may receive both cava or only 1
 Can also form tunnel type lesion btw 2 chambers

o Majority of dogs
 Low pressure distal chamber
* Receive CrVC
* Contain TV
 Proximal high pressure chamber
* Receive CaVC + CS

o TV can be in either chamber depending on membrane site and angle, usually membrane above TV

o Perforation of membrane vary in size
 Variable degree of obstruction to flow
 Often visible on 2D echo w/o color Doppler
 Chiari network: diffuse membrane w many fenestrations
* Variant of this defect
* Usually not hemodynamically significant
o Dilation of cranial chamber and vena cava if significant obstruction

Question 10

CTD: Doppler echo

Answer 10

o Turbulent flow across defect, usually low velocity
o PG present btw 2 chambers

Question 11

CTD: cardiac KT pressure study

Answer 11

• Pressure study: 2 catheter used
  o Femoral vein → caudal chamber
   ↑ pressure >10mmHg
  o Jugular vein → cranial chamber
   Normal RA pressure

Question 12

CTD: cardiac KT angio

Answer 12

o Contrast injected into cranial chamber → normal flow to R heart
o Contrast injected into caudal chamber
 Enlarged caudal chamber
 Dilated CaVC
 Contrast jetting into cranial chamber through perforation
* If membrane imperforated → collateral vessels → cranial chamber

Question 13

CTD: bubble study

Answer 13

o R cephalic: normal CrVC → RA communication
o L saphenous : obstruction of flow from CaVC → ↓ bubbles in RA
 Other venous path possible: collaterals or azygos

Question 14

CTD: natural history

Answer 14

• 1 report of a dog w 3 chambered RA
  o Each cava emptied into 1 chamber
  o Both chambers communicated w 3rd chamber
  o 3rd chamber was associated w TV

Question 15

CTD tx

Answer 15

surgical resection
balloon dilation

Question 16

CTS: embryology

Answer 16

• Common PV originate from outpouching of LA → connects w/ primitive PVs
• CTS forms from
  o Stenosis of common PV
  o Failure of incorporation into LA

Question 17

CTS: Gross examination

Answer 17

• Additional, accessory left atrial chamber
  o Separated by a membrane of fibromuscular tissue
   Divide LA in cranial and caudal chamber
• Upper/proximal chamber: connect w/ PVs
• Lower/distal chamber: connect w/ MV, LAA and fossa ovalis
   Hole or fenestration allow communication btw chambers

Question 18

Types of CTS

Answer 18

o Type A: classic CTS → proximal chamber receives all PVs
o Type B: proximal chamber receives all PVs but no communication w/ true LA (distal ch.)
o Type C: proximal chamber receives part of PVs, other connect normally to distal chamber or to RA

Question 19

CTS pathophys

Answer 19

• Intra atrial membrane ↑ resistance to flow
  o ↑ pressure in proximal chamber → pulmonary veins → capillaries → pulmonary edema
  o Obstruction of PV return and LV inflow

Question 20

CTS signalment

Answer 20

• Signalment: reported in cats

Question 21

CTS PE

Answer 21

• PE: no heart murmur or diastolic

Question 22

CTS 2D echo

Answer 22

• 2D echo:
  o Echobright linear structure above MV
   LAA connected to distal chamber
  o Normal MV appearance and motion
• In region of RPA on SAX

Question 23

CTS Doppler echo

Answer 23

• Doppler: continuous flow through region of obstruction

Question 24

CTS vs supravalvular MV stenosis echo

Answer 24

o Vs supravalvular MV stenosis: flow is only diastolic
CTS:  LAA connected to distal chamber

Question 25

CTS tx

Answer 25

• Treatment: surgical resection, balloon
  o CHF tx