1
Q
Describe the anatomy of the LAD.
A
- Courses anteriorly and inferiorly in the anterior interventricular groove towards the apex
- Occasionally, the LAD continues around the apex to supply part of the posterior interventricular groove
2
Q
Define the 4 different types of LAD.
A
Type 1: does not supply the LV apex
Type 2: the LAD and right coronary both supply the apex
Type 3: supplies the entire apex
Type 4: supplies the apex and >25% of the inferior wall (wraps around)
3
Q
What are the main branches of the LAD?
A
- Diagonal arteries (2-6) course along and supply the anterolateral wall of the LV
- Septal perforators (3-5) branch perpendicularly into and supply the anterior 2/3s of the ventricular septum
- RV branches which supply blood to the anterior surface of the RV (not always present)
4
Q
What is clinically relevant about the first septal perforator?
A
The first septal artery is the largest and runs perpendicularly towards the medial papillary muscle of the TV. *It is at risk during the Ross procedure because it lies immediately beneath the RVOT and pulmonary valve
5
Q
How is the LAD divided?
A
- Proximal 1/3: origin of the LAD to the origin of the first septal artery
- Middle 1/3: first septal artery to the origin of the last diagonal artery
- Distal 1/3: last diagonal artery to the termination of the LAD
6
Q
Describe the anatomy of the circumflex coronary artery.
A
- Courses along the left AV groove and in 85-90% of patients terminates before reaching the posterior interventricular groove
- In 10-15% of patients the circumflex continues as the PDA.
7
Q
What are the main branches of the circumflex coronary artery?
A
- Obtuse marginal arteries supply the lateral aspect of the LV wall, including the anterolateral papillary muscle of the MV
- LA branches
- SA nodal artery (45%)
- AV nodal artery (10-15%)
- PDA (10-15%)
8
Q
Describe the anatomy of the RCA.
A
- Courses anteriorly and laterally from its origin, descending in the right AV groove and inferiorly towards the acute margin of the RV
- Courses around to the inferior surface as the PDA and continues as the posterior LV artery
9
Q
What are the main branches of the RCA?
A
- SA nodal artery (55%)
- Conus branch that courses anteriorly over the right ventricular infundibulum
- Acute marginal branch that courses over the acute margin of the RV
- Anterior RV branches that supply the anterior free wall of the RV
- AV nodal artery (85-90%)
- PDA (85-90%), runs in the posterior interventricular groove and gives off septal perforator arteries which branch perpendicularly and supply the posterior 1/3 of the ventricular septum
- Posterior LV artery that supplies the posterior surface of the LV
10
Q
How is dominance of the coronary artery system determined?
A
- Refers to the artery from which the PDA and PLV originate from
- Right dominant system occurs in 80-85%
- Left dominant system 10-15% (more common in males and BAV)
- Co-dominant 5%
11
Q
Describe the coronary venous drainage system.
A
- Majority drain via the coronary sinus into the RA
- Coronary sinus is a continuation of the great cardiac vein
- Coronary sinus is demarcated by the valve of Vieussens and entry of the oblique vein of the LA
12
Q
What are the anatomical locations of the main coronary veins and their artery counterparts?
A
- Coronary sinus - left AV groove, circumflex
- Great cardiac vein - anterior interventricular groove into the left AV groove, LAD + circumflex
- Middle cardiac vein - posterior interventricular groove, PDA
- Small cardiac vein - right AV groove, RCA + acute marginal artery
13
Q
Describe the conduction system.
A
Consists of the
(1) SA node
(2) AV node
(3) bundle of His
(4) bundle branches
(5) Purkinje fibers
14
Q
Where is the SA node?
A
Found in the upper part of the wall of the RA, just lateral to the sinus venarum at the junction where the SVC enters the RA
15
Q
Where is the AV node?
A
Lies near the opening of the coronary sinus, located at the center of Koch’s triangle.
16
Q
Where is the bundle of His?
A
Penetrates the central fibrous body to reach the membranous septum to lie on the crest of the muscular ventricular septum beneath the right and non-coronary cusps of the AV
17
Q
Describe the left and right bundle branch.
A
LBB, divides into anterior and posterior fascicles that run sub-endocardially down the septal surface of the LV to the apex
RBB which runs on the right side of the ventricular septum towards the base of the medial papillary muscle of the TV into the body of the septomarginal trabeculation and traversing the RV cavity through the moderator band
18
Q
What is the blood supply of the SA node?
A
The SA nodal artery originates from the RCA in 55% of patients and the circumflex in 45% of patients
The SA nodal artery passes in front of the junction between the SVC and RA roof in 60% of patients, behind the junction in 33% and around the junction in 7%
19
Q
Describe the location of the AV node.
A
The AV node lies within the triangle of Koch
The boundaries of the triangle of Koch include; (1) tendon of Todaro (2) hinge of the septal leaflet of the TV (3) superior margin of the coronary sinus
The membranous septum lies just superior to the triangle of Koch and is where the bundle of His penetrates to enter the muscular septum
20
Q
What is the blood supply of the AV node?
A
The AV nodal artery supplies the node and originates from the RCA in 85-90% of patients with the remaining 10-15% originating from the circumflex.
21
Q
Describe the anatomy of the aortic valve.
A
- Three semilunar leaflets (RCC, LCC, NCC)
- Nodule of Arantius = thickened free edge of the leaflet
- Leaflets coapt at the free edge of their ventricular surface
- Commissures are the points of contact between the leaflets on the aortic wall
22
Q
Describe the anatomy of the aortic root.
A
- Aortic valve leaflets
- sinuses of Valsalva; allows the aortic valve leaflets to fall back during systole
- ST junction between the distal part of the sinuses and the proximal ascending aorta
- Ventriculo-arterial junction between the ventricular myocardium and aortic sinuses
* the level of the basal attachment of the cusps is lower than the anatomical VA junction
23
Q
Describe the anatomy of the pulmonary valve.
A
Three semilunar leaflets (right, left and anterior)
24
Q
Describe the anatomy of the mitral valve.
A
- Two leaflets (anterior and posterior)
- The leaflets are subdivided by clefts into scallops
- The posterior mitral valve annulus takes up 2/3 of the circumference
- The anterior mitral valve takes up 2/3 of the cross-sectional area of the mitral valve orifice
25
Describe the tension apparatus of the mitral valve.
1. Leaflets
2. Mitral valve annulus, which contracts during ventricular systole
3. Papillary muscles anterolateral & posteromedial
4. Chordae tendinea
5. Left ventricle
26
How many chordae tendinea are there?
1. Primary (free edge) run from the papillary muscles to the free edge of the leaflets
2. Secondary (strut chordae) which run from the papillary muscles to the roughened zone on the ventricular surface of each leaflet
3. Tertiary (basal chordae) which run from the papillary muscles or ventricular wall to the base of the leaflets
27
Describe the anatomy of the tricupsid valve.
1. Three leaflets (anterior (largest), septal and posterior (smallest))
2. Two or three papillary muscles that support the TV
28
What is the blood supply to the papillary muscles of the mitral valve?
1. Anterolateral papillary muscle has a single head and is supplied by the circumflex coronary & LAD
2. Posteromedial papillary muscle has multiple heads and is supplied by the RCA
29
Describe the papillary muscles of the TV.
1. Anterior papillary muscle (largest), arises from the moderator band and supports the anterior leaflet and the zone of apposition between the anterior and posterior
2. Medial papillary muscle (of Lancisi) supports the septal leaflet and the zone of apposition between the septal and anterior leaflets
3. Posterior papillary muscle (smallest) supports the posterior leaflet and the zone of apposition between the posterior and septal
30
Which papillary muscle does the right bundle branch pass through?
Medial papillary muscle
31
Describe the anatomy of the left main coronary artery.
1. LM coronary courses in an anterior and inferior direction between pulmonary trunk and LA appendage
2. Typically 10-40mm in length
3. It generally bifurcates into the LAD and circumflex, occasionally trifurcates
32
What are the layers of the pericardium?
Two layers (1) fibrous pericardium and (2) serous pericardium (lined by mesothelial cells which secrete and resorb pericardial fluid)
Serous pericardium has
(1) visceral pericardium, which is adherent to the epicardium
(2) parietal pericardium which is adherent to the fibrous pericardium.
5-10mL of pericardial fluid lies within the pericardial space (between the visceral and parietal pericardium)
33
Where is the oblique sinus?
Lies posterior to the LA between the four pulmonary veins and medial to the IVC.
34
Where is the transverse sinus?
Lies behind the aorta and pulmonary trunk but in front of the superior vena cava and left atrial appendage.
35
Describe the anatomical location of the femoral artery.
Located at the mid-inguinal point which is halfway between the anterior superior iliac spine and the symphysis pubis.
Commences just beneath the inguinal ligament. It gives off the profunda femoris laterally and then continues as the superficial femoral artery.
36
Describe the course of the common femoral vein.
Located medial to the femoral artery.
Formed from the confluence of the deep and superficial femoral veins just proximal to its junction with the long saphenous vein.
Continues as the external iliac vein when it passes under the inguinal ligament.
37
Describe the course and landmarks of the greater saphenous vein.
Commences just anterior and superior to the medial malleolus.
Continues up the medial aspect of the lower leg (with the saphenous nerve) before turning slightly posteriorly at the superior aspect of gastrocnemius.
The vein then passes medial to the knee joint (posterior to the medial aspect of the patella).
From the knee, the vein continues up the medial aspect of the thigh to drain into the common femoral vein at the saphenofemoral junction.
38
Where is the saphenofemoral junction?
It is located 3cm inferior and 3cm medial to the femoral artery pulsation.
39
Describe the course and landmarks of the lesser saphenous vein.
Located 2cm posterior to the lateral malleolus.
Courses superiorly superficial to the gastrocnemius muscle in the midline of the lower leg and runs in close proximity to the sural nerve.
Terminates by draining into the popliteal vein below the knee.
40
Describe the anatomy of the LIMA.
The LIMA originates from the subclavian artery medial to scalenus anterior.
Lies between the transversus thoracics muscle layer and the internal intercostal muscle layer.
It courses down the posterior aspect of the chest wall 2cm lateral to the left sternal edge with corresponding LIM veins on either side.
It terminates ~6th intercostal space by dividing into the (1) superior epigastric artery and (2) musculophrenic artery.
41
What are the branches of the LIMA and what do they supply?
(1) intercostal branches, originate anteriorly into the intercostal spaces
(2) perforating branches which pass anteriorly and supply the overlying muscles including pectoralis major
(3) sternal branches
(4) percardiophrenic artery which supplies the phrenic nerve and lateral aspect of the percardium.
(5) superior epigastric artery which supplies the muscles of the superior aspect of the anterior abdominal wall including rectus abdominis.
(6) muscolophrenic artery which supplies branches to the 6th-10th intercostal spaces.
42
Describe the anatomy of the radial artery?
Located medial to the biceps tendon.
Three parts; proximal, middle, distal.
Covered by the brachioradialis muscle.
Branches include the recurrent radial artery, superficial palmar artery and muscular branches.
Terminates at the level of the radial styloid process and continues as the deep palmar artery.
43
Where is the proximal radial artery?
Lies between the its origin and the distal extent of the antecubital fossa.
Lies above the brachialis, pronator teres and supinator muscle.
44
Where is the middle radial artery?
Extends from antecubital fossa up to the origin of the tends of brachioradialis, ECRL and ECRB.
Lies above the pronator teres, flexor digitorum superficialis and flexor pollicis longus.
45
Where is the distal radial artery?
Runs from the origin of these tends to the wrist crease.
Lies above the flexor pollicis longus, flexor digitorum profundus and pronator quadratus.
46
What are the main nerves at risk during radial artery harvest?
(1) lateral cutaneous nerve of the forearm (nerve roots C5-C6) which carries sensory fibres to the lateral aspect of the forearm.
(2) superficial radial nerve (nerve roots C7-C8) which crosses the anatomical snuffbox and carries sensory fibres to the thenar eminence.
47
Describe the anatomy of the phrenic nerve.
Originates from the C3-C5 nerve roots.
Lies anterior to scalenus anterior.
Passes posterior to the subclavian artery.
Passes medially to the internal mammary artery to lie on the lateral surface of the pericardium.
The right phrenic nerve passes through the IVC opening of the diaphram at the level of T8.
The left phrenic nerve pierces the muscular part of the left hemi-diaphragm.
Terminates by branching on the inferior surface of the diaphragm.
48
What does the phrenic nerve supply?
(1) Motor function to the diaphragm.
| (2) Sensory function to the diaphragm and anterior chest and abdominal wall.
49
Describe the anatomy of the descending thoracic aorta.
Starts just distal to the origin of the left suclavian artery.
Terminates at the diaphragm where it passes through the aortic hiatus.
Lies on the posterior thoracic wall and anterior to the vertebral column as it passes through the diaphragm.
50
What structures pass through the aortic hiatus?
(1) Descending thoracic aorta (2) thoracic duct (3) azygos veins
51
What are the branches of the descending thoracic aorta?
(1) Pericardial branches
(2) Bronchial arteries
(3) Esophageal branches
(4) Mediastinal branches
(5) Intercostal arteries
(6) Subcostal arteries
(6) Superior phrenic arteries
52
Describe the anatomy of the axillary artery.
Continuation of the subclavian artery and commences at the outer edge of the 1st rib.
Terminates at the lower border of teres major where it continues as the brachial artery.
Lies within the axillary sheath with the axillary vein and brachial plexus.
53
What are the three segments of the axillary artery?
Axillary artery is divided into three parts by the pectoralis major muscle.
```
1st segment (above):
(1) superior thoracic artery
```
2nd segment (behind):
(1) thoracoacromial artery
(2) lateral thoracic artery
3rd segment (below):
(1) subscapular artery (circumflex scapular and thoracodorsal)
(2) posterior humeral circumflex artery
(3) anterior humeral circumflex artery
54
How is the heart formed embryologically?
The heart tube forms from fusion of the two ventral aorta which originate from the mesodermal layer of the yolk sac.
Longitudinal growth/rotation it divides into (1) conus truncus (2) sinus venosus (3) bulbus cordis.
Endocardial cushions form between atria and ventricles within the heart tube to create AV canals --> mitral/tricupsid valves.
Atrial septum forms from the septum primum and septum secundum, leaving a small opening (the foramen ovale)
The muscular part of the interventricular septum forms from the ventricular myocardium of both ventricles, wheres the membranous part originates from fusion of the endocardial cushions and the descending truncal cushions.
Cardiac Surgery
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