patho logy c v anat omy and histo logy

7/29/2019 Patho logy C V Anat omy and Histo logy

1/11

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


2/11

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?


4/11

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


5/11

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


6/11

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:


8/11

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%)


9/11

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


11/11

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!!!

patho logy c v anat omy and histo logy

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