Morphology session

Atrial morphology is defined based on: The extent of pectinate muscles The shape of the atrial appendages The appearance of the atrial septum and oval fossa

Left atrial appendage: Thin at the base - crooked finger appendate; Left atrial appendage: Crooked finger-like Narrow base -    Pectinate muscles only within appendage. If cath into the RA, and goes through the foramen ovale, into the left atrium. Cathether can go straight into the left atrium appendage. The appendage is delicate and pectinate muscles. It is very thin, you have high risk of perforating the left atrial appendage. 

Right atrial appendage: large base, Right atrial appendage: - Blunt, mitt-like - Pectinate muscles extend to right atrial wall. 

Smooth walled atrium = LA. 

Pectinate walled atrium = RA

Appearance of atrial septum can also provide information about the atrial morphology and relationship. Oval Fossa - septum primum is at the bottom of the oval fossa. Inverted C when seeing from the right atrium. The "C" on the septum primum side when looking from the morphological LA is inverted in relationship to the 

A fold that is common to see in the left atrium = the "comedone ridge" is also known as the Coumadin ridge or Warfarin ridge, and it's a normal anatomical feature of the left atrium, a chamber of the heart.

Tricuspid valve septal leaflet

Anterior superior leaflet of the tricuspid valve. 

There is a crucial corner that meets the anterior superior leaflet of the TV and the septal leaflet of TV. 

Eustachian vlave that protects the entrance of the IVC

The Thebesian valve that entrance the enterance of the coronary sinus. 

Fold part of the eustachian valve an drunning underneath the fossa ovalis. There is a triangle between the hinge line of the septal leaflet of the TV. Triangle of Koch. This is where the AV node is located at the apex of that. 

Boundaries of the Triangle of Koch: 

Tendon of Todaro – a fibrous band running from the Eustachian valve to the central fibrous body Orifice of the coronary sinus – located inferiorly 

Hinge point of the Septal leaflet of the tricuspid valve – forming the anterior boundary

Clinical significance: The AV node lies within this triangle, close to the apex. It's a key landmark during catheter ablation procedures for arrhythmias like AV nodal reentry tachycardia (AVNRT). Careful identification of this triangle helps avoid injury to the conduction system during surgery or intervention.

large ASD closure devices at that zone could impinge on the triangle and cause issues with the AV node and lead to heart block or bradycardia. 

If you have bilateral left isomerism - you may have no sinus node. 

Usually, the sinus node is attached to the right atrium, and usually at the junction of the SVC to the RA

You have to be careful of the SA node artery, which can be impinged with tying / suturing cannulas like hte ECMO cannula. Sinus node artery can be variable where it comes from. 

ASD:

• In fossa ovalis 

• Sinus venosus defect near SVC or IVC (inferior or supuerior one)

• Coronary sinus orifice defect. Usually occurs when there is unroofed SVC, Left SVC going to the coronary sinus. 

PFO: Fold

Secundum ASD = big deficiency of the fossa ovalis. There is no primary septum through that hole. Atrial Septal Defect within the Oval Fossa - "Secundum ASD". 

Sinus nveosus defect are usually associated with anomalous pulmonary venous drainage. The defect is not in the atrial septum, it is often time a pulmonary veins going directly into directly at SVC at the junction of RA, or into IVC at junction of RA. 

Sick Sinus Syndrome, junctional escapes, sinus bradycardia, supraventricular beats in context of sinus venosus defect. 

Tricuspid valve inserts more apical than the mitral valve. 

Common AV junction = AV valve is stream right accross from one end to another. AV valves at the same levels. You can have common AV valve without having the defects (very rare). You may have what looks like a "cleft" mitral valve. - but it is the anatomy of the valve. It is one valve that composes the whole AV junction. 

In fetal life, we see a "match-stick". Could be because there is a wall with also a secundum defect on top of the primum defect. 

Fine criss-cross trabeculations in the LV. Coarse in the RV. 

Anti-clockwise rotation of the papillary muscles in the AVSD. 

Two bridging leaflets of the left-sided AV valve - there is a superior and inferior briding leaflets, creating as if there is a division or a cleft. 

RV: Inlet undeneath the septal leaflet of the TV and the chordal attachments, the APICal trabecular component, and hte outlet that is smooth walled under the pulmonary valve / RVOT. 

The medial papillary muscle. Good way to locate PM-VSD in the membranous septum. sends chordae some to the septal leaflet and some to the anterior-superior leaftlet of TV.

The medial papillary muscle is at the top of the septal band. At the end of it there is a moderator band. 

On the left ventricle, you dont have a free-standing a moderator band that goes accross it. 

Septal attachments to the tricuspid valve. 

Defect touches that fibrous part of the ventricular septum. 

You are close to the bundle of his near the PM VSD. 

There is a space where you can puncture through the membranous septum and arrive from the right atrium into the left ventricle. These can create a Gerbode effect. 

VSD named based on the right side - because this is where we approach the surgery. Especially when it is muscular VSD, sometimes the trabeculations are so deep that it is challenging to see where it is a whole. 

Most of the time it is the right coronary cusp that can be suctioned and cause aortic insufficiency. 

Bundle of His is typically more leftward, so we arecoming from the right side and putting patch but still have to be careful in not injurying the bundle of his. 

Swiss cheese trabecular defects = muscular tends to close. 

Conal septum is malaligned

encroachment of the aorta 

Anterior malalignment of the conal septum. 

DORV could be because  there is no continuity of the mitral valve and aortic valve. 

>> 50% commitment of the Aorta to the RV = DORV

If there is muscle between TV and the Aorta = no conducting system. But if fibrous tissue = conducting system there.