heart and conduction system

8/14/2019 Heart and conduction system

1/25

10/13/2013 7:17:00 PM

Describe the physical layout of the heart within the middle mediastinum heartborders and surface anatomy)

- The Base of the Heart is posterior and opposite to the apex

- Formed from mainly the left atrium and part of the right atrium

- T5-T8 Vertebrae

- Receives (R/L) pulmonary veins on its left atrial portion

- Receives SVC and IVC on its right atrial portion

Heart Borders & Surface AnatomyArch of aorta

Apex of Heart- Formed by the left ventricle- Lies deep to 5thintercostalspace- Handbreadth from midline

Right border

-Right atrium,SVC and IVC

Left border

- Formed byleft ventricle

Left pulmonary a.

Radiographic appearance of heart

Arch of

aorta


2/25

CR) Mitral valve insufficiency Mitral valves leaflet disorder Blood regurgitates back into the left atrium The left atrium dilates which causes compression of the esophagus = dysphagia

Esophagus

Thoracicaorta

Anatomical orientation of Heart

Right= right atrium

Left= left ventricle

Anterior/sternocostal= right

ventricle

Posterior/base= left atrium

Superior= atria andauricles, great vessels

Heart Borders


3/25

Describe the pericardium: composition, sinuses, blood and nervous supply and clinical implicationsregarding this structure.The pericardium is a fibrous membrane that covers the heart and the origins of the great vessels.Contains 3 layers:i) Fibrous Pericardium:

Attached to the central tendon of diaphragm and sternum

ii) Serous Pericardium (Parietal Layer)iii) Serous Pericardium ( Visceral Layer) epicardium

There is a Pericardial Cavity:

Space between parietal and visceral layerPericardial Fluid that is contained within the Pericardial Cavity. Secreted by Serous Mesothelium

.


4/25

Pericardial Sinuses:

Transverse sinus:o Passage behind ascending aorta and pulmonary trunk

Oblique sinus:o Posterior to the hearto Reflection of pericardium surrounding the pulmonary veins, IVC and pericardium

overlaying the esophagus

o

CR) Transverse Sinus to clamp Ascending Aorta and Pulmonary Trunk during Cardiac surgery

Blood Supply and Innervation of the Pericardium:

T

OLooping of primordial heart

Embryology

O

T


5/25

Arterial Supplyo Branch of the Internal Thoracic Artery.

Pericardiacophrenic Artery Musculophrenic Artery

o Branch of Thoracic Aorta Bronchial Esophogeal Superior Phrenic

o Coronary Artery (to visceral layer) Venous Drainage

o Pericardiacophrenic Veino Azygous venous system tributaries

Nervous supplyo Phrenic Nerves (C3, C4, C5)o Vagus via cardiac plexuso Symphathetic trunks

o

racic A..

aorta

eral layer)

ributaries

Pericardiacophrenic

artery & vein

And Phrenic nerve

Vagus

nerve

Internal thoracic artery


6/25

CR) Pericarditis: Inflammation Pericardial Friction Rub, sounds like rustle of silk

CR) Pericardial Effusion: Fluid from pericardial caps into pericardial cavity (pus accumulation)CR) Cardiac Tamponade heart compressions): Result from extensive pericardial effusion (poor pericardiocentesis)

o Compressed volume doesnt allow the heart tofully expand -> limit amount of bloodthe heart receives -> decrease CO

o Hemopericardium blood in the pericardial cavity Symptom BECKs TRIAD

i. Hypotension ( due to decrease in CO, caused by decrease stroke vol)ii. Jugular Venous Distensioniii. Muffled Heart Sounds

CR) Pericardiocentesis: Withdraw of fluid from the pericardial sac at 5/6thintercostal space near sternum, close to

the infrasternal angle

Describe the 4 chambers of the heart: what structures are found within each chamber eg-similarities and differences between right and left ventricles) and any associated embryologicalorigins/remnants.


7/25

Right Atrium:

Receives Venous blood from four vesselsi. Superior Vena Cavaii. Inferior Vena Cavaiii. Coronary Sinusiv. Anterior Cardiac Veins

Right

atrium

Leftatrium

LeftventricleRightVentricle


8/25

o Internal structures

o Sinus Venarum the smooth portion of the chamber Embryological Origin: Sinus Venosus

o Pectinate muscle the rough portion of the chamber Embryological Origin: Primitive Atrium

o Crista Terminalis Separates the rough portion from the smooth portion. (externalportion of the Crista Terminalis = the Sulcus Terminalis)

o Fossa Ovalis Embryological Origin: Foramen Ovale

o Auricle

Right Ventricle:

Auricle

Fossa ovalis

Opening of

coronary sinus

Crista terminalis

SVC

IVC

Pectinate muscle

Sinus

venarum

Adult structure Embryologic origin

Sinus venarum Sinus venosus

Trabeculated pts. Primitive atrium

Fossa ovalis Foramen ovale


9/25

Trabeculae Carneae rough portion

o Embryological Origin: Primitive Ventricle Conus Arteriosus/Infundibulum Smooth Portion

o Leads to pulmonary trunk through the pulmonary valveo Embryological Origin: Bulbus Cordis

Tricuspid Valveo Chordae Tendineaeo Papillary Muscles

1. Anterior2. Posterior3. Septal

Septomarginal Trabeculae (Moderator Band)o Contains right branch of the AV bundleo

Pulmonary Trunk: Take poorly oxygenated blood from the right ventricle to lungs

o Divide to right and left pulmonary arteries

Trabeculae carneae

Tricuspid valve

Chordae

tendineae

Septomarginal

trabecula

Pulmonary valve

Conus

arteriosus

Papillary

muscle

A

S

P

n


Conus arteriosus Bulbus cordis

Trabeculated pts. Primitive ventricle


10/25

oLeft Atrium:

Receives venous blood O2 rich, from 4 pulmonary veins (2 superior and 2 inferior)

Internal Aspecto Large smooth wall portion and smaller muscular portion than the right atriumo Auricle has pectinate muscleso Semilunar depresson floor of foosa ovalis

Valve of the oval fossa (surrounding ridge)

Left pulmonary

artery

Left pulmonary

artery

Pulmonary

Trunk

in

of

Auricle

Floor of

Fossa ovalisPulmonary

veins


Left atrium Pulmonary venous

tissue


11/25

Left Ventricle:

Internal aspecto Trabeculae Carneae - rough portiono Aortic Vestibule smooth portion

Leads to Aorta through aortic valveo Bicuspid Mitral Valve

Choradae Tendineae Papillary Muscles

01. Anterior02.Posterior

Thicker wall than Right Ventricle

tricle

t)

Chordae

tendineae

Trabeculae carneae

Papillary

muscles

Bicuspid valve

A

P

Aortic

vestibule


12/25

Valves: Tricuspid Valve

o RA to RV Pulmonary/pulmonic Valve

o RV to Pulmonary Trunk Mitral Valve (bicuspid)

o LA to LV Aortic Valve

o LV to Aorta

In the diagram it shows the coronary arteries feeding into the aortic valve

Diagram the flow of blood through the heart.


13/25

Blood Flow Through the Heart Initially there is inflow from the Superior Vena Cava towards the Atrial Ventricular Orifice. There is also inflow from the Inferior Vena Cava towards the Fossa Ovalis

From the right atrium to the right ventricle the flow is right to left via the tricuspid valvedue to the orientation of the heart.

The right ventricle the flow takes a U-turn and is directed superior to the pulmonary valve.

Pulmonary

Circulation

Systemic

Circulation

AV orifice

Fossa

ovalis


14/25

The inflow into the left atrium from the 4 pulmonary veins ( 2 superior 2 inferior) isdownward and left

Inflow from the left atrium into the left ventricle is through the bicuspid Mitral Valve. Theflow makes a U-turn directed superiorly

Outflow is from left ventricle towards its the apex/Aortic Valve

Tricupsid valve

Pulmonary valv

Mitral valve


15/25

Cardiac Cycle and Valves:

Differentiate between heart valves placement and auscultation.

Mitral valve

iastole

ystole

Beginning of diastole(Closure of A & P valves

produceDubsound)

Early & during diastole

(AV valves Opens)Late diastole

(Atrial contraction)

Beginning of systole

(High ventricular pressure close AV valves

produce Lubsound)During systole

(Opening of A & P valves)

Cardiac Cycles and Valves

http://www.youtube.com/

watch?v=NeMJXMSkA7g


16/25

Mnemonic: All Physicians Take Money

Auscultation site are the areas where the sound is most clear, not where the valve is located

CR) Valvular Heart DiseasesInsufficiencies: failure of valve to close completely

Stenosis: failure of the valves to fully open

Describe the coronary arteries: their branches and anastomoses between the different arteries,dominance of the heart, disease processes associated with the coronary arteries.Vasculature of the Heart:

Coronary Arterieso Right and left

First the branches of the aortao Arise from Rt and Lt aortic sinuses

Cardiac Veinso Greato Middle

Heart valves location vs auscultation sites

Location (white circles)

Aortic- medialaspect of left 3rd

intercostal space,

behind sternum

Pulmonic-medialaspect of left 3rd

costal cartilage

Tricuspid-medialaspect of right 5th

costal cartilage,

behind sternum

Mitral-medial

aspect of left 3rd

intercostal space

Auscultation site (red circles)

Aortic-2ndintercostal space,

right parasternal

Pulmonic-2ndintercostal space,

left parasternal

Tricuspid- 5thintercostal space,

left parasternal

Mitral- 5thintercostalspace, left

midclavicular line


17/25

o Small Cardiac Veinso Coronary Sinus (walls made of cardiac muscle not smooth)o Thebesian Cardiac Veins

Right Coronary Artery: 4 Branches

o SA Nodeo Right Marginalo AV Nodeo Posterior Interventricular

Supplies blood too Right atriumo Right ventricleo Posterior 1/3 of interventricular septumo SA and AV nodes

Left Coronary Artery: 2 Branches

o Anterior Interventricular (left anterior descending) A branch off the interventricular = the Diagonal Branch

o Circumflex A branch off the circumflex = Left Marginal

Supplies blood to:o Left atriumo Left ventricleo Portion of the right ventricleo Anterior 2/3 of interventricular septumo AV nodeo SA node in 40%

R L

Anterior

RV LV

Anterior view Posterior v

Contains 4 branches

SA nodal

Right marginal

AV nodal

Posterior interventricular

Right marginal

SA node

AV node

RCA supplies: right atrium, right ventricle, post. 1/3interventricular

septum, SA and AV nodes.

RCA supply= Dark pi


18/25


19/25


20/25

Placed after dilation of vessel. Maintain dilation

CR) Coronary Artery Bypass Graft Arteries and veins from else where to reroute blood flow to heart Arterial Stenosis or Arterial Atresia

o Arterial Internal Thoracic Radial Gastroepiploic Inferior epigastric

o Venous Great Saphenous Small Saphenous

Explain the location of the structures that are involved with the conduction system of the heart.


21/25

CR) Damage of Conducting System

Cause Ischemia LAD -> AV buddle branch RVC -> SA node and sometimes AV Ventricles contract Independently Unilateral damage of bundles -> late asynchronous contraction of ventricles

CR) Pacemakers Replaces SA node Pathway of the pacemaker in the heart: Left Subclavian vein -> left brachiocephalic vein -

>Superior Vena Cava -> Right atrium -> right ventricle (Trabeculae Carneae)

xplain the innervation of heart and the concept of Heart referred pain.

Conduction system

structure

Location within the heart

Sinuatrial (SA) node Located in the Rt. atrium between Crista terminalis and opening of SVC

Bachmanns Bundle Right to Left atrium

Atrioventricular (AV)

node

Located in the Rt atrium at interatrial septum close to the opening of

coronary sinus.

Bundle of His Membranous pt. of interventricular (IV) septum

Right bundle branches Muscular IV septum, moderator band, wall of R. ventricle

Left bundle branches Muscular IV septum, wall of L. ventricle

Purkinje fibers

(subendocardial brs.)

Right side- IVS, wall of R. ventricle, Ant. papillary muscle

Left side- IVS, wall of L. ventricle, Ant. and Post. papillary muscle

Conduction System

of Heart


22/25

Parasympathetic

o Vagus Sympathetic

o Presynaptic (T1-T4)o Postsynaptic Cervical and Superior Thoracic Ganglia

Visceral Afferento With Sympathetico Transmit Noxious stimuli

Visceral Afferent

Pain from heart to visceral afferent, travel with sympathetic Perceived as peripheral pain Enters spinal cord through same posterior dorsal root with somatic sensory fibers Pain in:

o Medial upper limbo Necko Shouldero Jawo Pain through intercostobrachial nerve

Sp

cov


23/25

o

s

From Thoracic Lecture

In ter costob rach ial ne rv


24/25


25/25

10/13/2013 7:17:00 PM

heart and conduction system

Documents