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7/29/2019 Patho logy C V Anat omy and Histo logy
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Cardiovascular Pathology: Review of Anatomy and Histology
8/20/12
By 8 weeks, all parts of the heart are in place
After that, only remodeling occurs
Pregnancy Terminology: Dating Pregnancies
Gestational Age = postmenstrual age
Archaic system that we are stuck with"26 weeks pregnant" used in common context means gestational age
Developmental Age = Postconceptual Age
Used by pathologists/embryologists
Chest Anatomy --- Facts to know
Thymus is small in adults, prominent in infants
Position of the heart in the chest
Bulges more to the left than the right
"Dextracardia" = shifted to the right
Heart sits on the diaphragm
Diaphragmatic surface = posterior surface = posterial inferior surface
Parietal and visceral pericardium
Fluid sits inbetween
Configuration of Right Atrial Appendage
Location of Left Anterior Descending coronary artery
Aorta is always to the right of the Pulmonary Trunk
Heart Anatomy -- Items to know
Crux is where the four chambers meet
Three branches coming off Aortic Arch (from right to left)
1. Brachiocephalic --> R Common Carotid + R Subclavian
2. L Common Carotid
3. L Subclavian
Four Pulmonary Veins entering Left Atrium
Posterior descending Coronary Artery
Interior Heart Anatomy -- Structures to Know
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Inferior Vena Cava + Superior Vena Cava
Ostium of Coronary Sinus
Eustachian Valve
Inflow and Outflow tracts of Right Ventricle
Come from different embryologic sources
Conus -- muscle interposed between AV valve and Semilunar Valve
Left Ventricle wall is much thicker than right
Left Ventricle gets smoother towards as you go superiorHelpful in IDing ventricles if they are swapped
Heart Measurements
Term infant = 20g
Adult = 250-350 (males > female)
LV wall > RV wall (1.4 vs .4)
Myocardium Development
7 Weeks Developmental Age (9 week gestational age)
- Lots and lots of glycogen
- Large embryonal blood cells in capillariesNucleated blood cells!!!
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Adult Myocardium
- Anastomosing fibers
- Central Nuclei
glycogen
are the black dots near the nuclei?
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Myofiber = muscle fiber = muscle cell (multinucleated)
Composed of Myofibrils
image shows thickness of it it runs from top left corner to bottom right.
Myofibril = Many myofilaments together to form a functional unit (sarcomere)
Myofilaments = actin and myosin
Great picture representation: http://en.wikipedia.org/wiki/File:Skeletal_muscle.jpg
Myocyte
- branching- intercalated disks- can be a part of more than one fiber
-Contrast with skeletal muscle fibers:
- Do not anastomose- Peripheral nuclei
Sarcomere --- goes from Z-band to Z-band
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The Conduction System
Specialized myocytes in the SA and AV nodes have special properties of excitation and/or conduction of electrical
impulses
Location helps you understand pathology of conduction disorders
Demand Pacemakers:
Only take over when required
SA Node = ~70bpm
AV Node = 40-50bpm
HIS Bundle/Purkinje = 16-20bpm
SA Node
Location right on the crest of appendage
Shown is SA node Artery specialized myofibers run in all directions
and help SA node conduction
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Shows the contrast between normal atrial myofibers (left) and
specialized myofibers or the SA node (right)
AV Node His Bundle
Location In the Triangle of Koch, in the lower portion of the Atrial Septum
Once it loses contact with the Atrial Myocardium, it becomes the His Bundle.
Histological Progression from AV Node to His Bundle:
Bundle Branches
Right Bundle Branch
Location:
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Histology:
Right bundle branch eventually turns into Purkinje fibers of the Right Ventricle
Left Bundle BranchNot really a branch --- more like a waterfalling cascade of fibers
Location:
Histology:
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Coronary Artery Anatomy
Left anterior coronary cusp Left main coronary artery Left Anterior Descending (LAD) + Left Circumflex (LCX)LAD: runs along anterior surface overlying the septum
Branches: First diagonal, First Septal Perforator, other septals, 2nd Diagonal, Right Ventricular,
Apical
LCX: Courses to the left within the AV groove, inferior to left atrial appendage
Branches: Obtuse Marginal Branch (supplies the lateral wall)
Right anterior coronary cusp Right coronary artery (RCA) Branch to the Conus + SA Nodal + Right Ventricular +
Right Atrial + Acute Marginal
Lots of posterior branches = if blocked, lots of posterior damage
85% of people are Right Coronary Dominant, meaning the posterior of the heart is mainly supplied by the
RCA
15% of people are Light Coronary Dominant, meaning that the LCA takes this role instead
versus (LCA Dominant 15%)
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The Circle and the U helpful concept to remember coronary artery positions
Circle formed by RCA and LCX
U formed by LAD and Posterior Descending
Valve Structure
Atrioventricular Valves (Tricuspid and Mitral) --- leaflets
Lamina Fibrosa = dense fibrous core
Spongiosa loose connective tissue on atrial aspect
AV valves are covered by thin layer of fibroelastic tissue & endocardium
also have BVs, lymphatics, nerve, smooth muscle, striated muscle
Blood Cysts can form in newborns along lines of closure --- they can be a normal finding
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Semilunar Valves cusps
No striated muscle, BVs, nerves, or lymphatics!!!!!
Both aspects of the cusp are covered by Fibroelastic tissue and endocardium
Blood Vessels
Walls consist mostly of endothelial cells and smooth muscle cells (SMC)
Also contains Extracellular matrix (ECM) elastin + collagen + GAGs
Three layers: Intima, Media, Adventitia
Intima endothelial cells + thin layer of ECM
External to intima is internal elastic membrane (lamina)
Media Smooth muscle cells + ECM
Some arteries also have an external elastic membrane
Adventitia loose CT + nerve fibers + smaller vessels (ie: vaso vasorum, supply muscle of the artery itself)
Large Arteries
Aorta, Aortas large branches (subclavian, common carotid, iliacs), Pulmonary trunk and arteries
Elastic fibers alternate with smooth muscle cells in layers
Elastic recoil provides energy to propel blood during diastole
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Aorta wall
Medium Arteries
Other aortic branches coronary arteries, renal arteries, mesenteric arteries
Branches from large aortic branches
Media = Smooth muscle cells with elastic fibers in internal and external elastic membranes
Small Arteries and Arterioles
Arterioles = 20-100mm in diameter
Small Arteries = 2mm or lessMedia = essentially all smooth muscle
Capillaries
Very small diameter only sufficient for free flow of RBCs
NO MEDIA!
Only endothelial lining
Essentially a tube of endothelial cells surrounded by basal lamina (protects endothelial cells)
Postcapillary Venules
Larger and distinguished by presence of pericytes
Veins
Thinner walls than arteries
Thinner mediaSmaller amount of smooth muscle
Contain elastic and reticular fibers
Valves are present!!!
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