echo anatomy

Heart

Hollow muscular organ that lies in central thoracic cavity slightly to the L of midline, between 3 and 5 intercostal spaces, anterior to vertebrae, posterior to sternum & lungs

Pericardium

• Fluid filled, loose, double layered sac of elastic connective tissue that encloses the heart

• 10-50mL of serous fluid (prevents friction)

• Surrounds heart and proximal ends of aorta, vena cava, & pulmonary artery

• Protects against infection, trauma, & friction

• Free pumping motion

Layers of pericardium

1. Fibrous (outer)

2. Serous (inner)

   1. Parietal layer lines inside of fibrous pericardium

   2. Visceral layer (epi) lines outside of heart

Pericardial space

Located between visceral & parietal layers. Contains clear fluid released by serous membrane that acts as lubricant to prevent friction during contraction & relaxation of heart

Pericardial effusion

In certain disease states the pericardial sac can fill with fluid

Right side of heart

• Low pressure

• Receive deoxygenated (venous) blood from body

• Pumps to lungs (pulmonary)

Left side of heart

• High pressure

• Receives oxygenated (arterial) blood from lungs

• Pumps to body (systemic)

What are atrial appendages (auricles)?

Blind pouches extending from each atrium that increase atrial surface area. Made up of pectinate muscles.

What are pectinate muscles and their function?

Parallel muscles in the atrial appendages that increase contractility without increasing muscle mass.

Where are the right and left atrial appendages located?

• Right: Extends over the aortic root.

• Left: Projects alongside the pulmonary artery.

Lining of RA

It is smooth except in the anterior wall and the atrial appendage

What is the interatrial septum (IAS) and what is the fossa ovalis?

• IAS separates R & L atria

• Fossa ovalis (closed window) is a slight depression that represents the closed foramen ovale (open window)

Right atrium location

• on the superior portion of the heart

• forms the right lateral cardiac border

• posterior and to the right of the RV

• mostly anterior to the LA

Which parts of the right atrium (RA) have thin walls, and which parts are more muscular?

The posterior wall is thin where the superior vena cava, inferior vena cava, and coronary sinus enter.

The anterior and inferior walls are more muscular because they contain the right atrial appendage and the tricuspid valve.

What is the torus aorticus?

A bulge on the medial wall of the right atrium formed by the right and noncoronary cusps of the aortic valve.

What vessels drain into the RA?

• Superior vena cava (SVC): Drains the upper body and head.

• Inferior vena cava (IVC): Drains the abdomen and lower extremities; its opening is guarded by the Eustachian valve, which may have a web-like Chiari network.

• Coronary sinus: Drains the myocardium via the coronary veins; its opening is guarded by the Thebesian valve.

Left atrium location

• lies superiority and posterior to the other cardiac structures

• it is the most posterior portion of the heart.

3 main functions of the LA

• LA acts as a reservoir during ventricular systole

• contracts to deliver blood to the LV

• serves as a conduit during LV filling

Key structural features of LA

The anterior LA is more muscular and contains the LA appendage with pectinate muscles. The rest of the LA is smooth, and the fossa oval is is present but less prominent

LA appendage & LA walls

LA appendage is a common site of thrombus (clot) formation and is best seen on TEE (transthoracic echo). The LA is slightly smaller than the RA but has thicker walls because of higher left sided pressures.

Ventricles

• located inferior to atria

• thicker walls due to higher pumping pressure

• IVS- triangular wall that separates the R and L ventricles

Right Ventricle

• receives o2 poor blood from RA during diastole & pumps blood to lungs during systole

• RV is the most anterior chamber, located beneath the sternum

• Crescent shaped

• thinner walls than LV

• contains irregular inner surface with trabeculae carneae

How does RV compare to LV in terms of trabeculae?

RV = heavily transected, especially compared to LV

Crista supraventricularis

Thick muscular ride in the RV that seperates the inflow and outflow tracts & arches over the anterior leaflet of the TV

What is the RVOT?

The superior/anterior, smooth, cone shaped portion of the RV called the conus arteriosus (infundibulum) that leads to the PV

Moderator band & function

Muscle in RV that extends from lower IVS to the RV free walk/pap muscle. It carries the RBB of the conduction system and helps prevent RV overexpansion.

Left Ventricle

• receives o2 blood from LA during diastole & pumps blood to aorta/body during systole

• ellipsoid/cone shaped, usually larger than RV, divider into an o flow & outflow tract

What forms the LVIT?

The MV annulus, mitral leaflets, & chordae from the funnel shaped LVIT

What is LVOT?

Surrounded by anterior mitral leaflets, IVS, & LV free wall & ends at aortic annulus

Why are LV walls thicker than RV walls?

LV walls are 2-3 times thicker because it pumps blood through high resistance systemic circuit

How does LV compare to the RV in muscle mass & trabeculation?

LV contains about 75% of hearts muscle mass & is less trabeculated than RV. The LV & RV have equal chamber volumes.

Valves & function

• 4 main valves prevent backward (retrograde) blood flow in heart.

• Semilunar: AOV & PV

• AV: TV & MV

SL valves & function

• AOV & PV

• located at the outlets of the ventricles. each has 3 fibrous cusps

When do SL valves open & close

They open when ventricular pressure is higher than the great vessels, allowing blood flow to the pulmonary and systemic circulation. They close when vent ventricular pressure drops, preventing blood from flowing back into the ventricles.

AOV location & function

• located in LVOT between LV & aorta

• allows blood to flow into aorta & prevents backflow into LV

What are the 3 cusps of AOV?

• RCC

• LCC

• NCC

What are the sinuses of Valsalva & why is it important

Pouch like areas behind each aortic cusp. The R & L sinuses give rise to the R & L coronary arteries

Arantius nodules & function

Small nodules at ends of each aortic cusp that support the cusps & help prevent valve leakage

What is the moral aortic valve area?

2-4 cm2

PV location & function

• right sided SL valve located in RVOT between the RV & MPA

• allows blood flow to lungs & prevents backflow into RV

What are the 3 cusps of the PV?

• anterior

• right posterior

• left posterior

How does PV compare to the AOV?

The PV cusps are slightly thinner than AOV cusps.

Normal valve area: 2-4 cm2

AV valves & location

• separate the atria & ventricles

• TV (R side)

• MV (bicuspid) (L side)

What structures support AV valves?

Supported by the valve annulus, chordae, & pap muscles

Function of AV valves

Inlet valves of the ventricles that prevent blood from flowing backward from the ventricles into atria

TV & location

• R AV valve

• located between RA & RV.

• larger & thinner than MV & sits more apically

3 leaflets of TV

• anterior- largest

• septal (medial)- attached to IVS

• posterior- smallest & attaches to tricuspid annulus (ring)

What supports TV leaflets

3 pap muscles connected by chordae. The chordae attach the leaflets to pap muscles.

Function of TV pap muscles & chordae

During ventricular contraction, the pap muscles pull leaflets together & downward, preventing valve from opening backward

Normal TV area

7-9 cm2

Characteristics of anterior medial mitral leaflet

It is triangular shaped, extends from the posterioromedial LV to the anterolateral LV wall, and is continuous with the posterior aortic root wall

Characteristics of posterior mitral leaflet

It is quadrangular shaped, longer than the anterior leaflet, and surrounds about 2/3 of the mitral valve opening (orifice)