Cardiac Cardiac Anatomy and PhysiologyAnatomy and Physiology

Jan BeyerJan BeyerRN, BSN, CCRN, EMTRN, BSN, CCRN, EMT

The BasicsThe Basics

ShapeShape LocationLocation ApexApex BaseBase WallsWalls

PericardiumPericardium

EndocardiumEndocardium MyocardiumMyocardium EpicardiumEpicardium

Pericardial SacPericardial Sac VisceralVisceral ParietalParietal

Coronary CirculationCoronary Circulation Venous:Venous:

SVCSVC IVCIVC Pulmonary veins x 4Pulmonary veins x 4 Coronary SinusCoronary Sinus

ArterialArterial AortaAorta

R common carotidR common carotid InnominateInnominate (brachial)(brachial)

L common carotidL common carotid L L subclaviansubclavian

PulmonaryPulmonary

Coronary ArteriesCoronary Arteries What do they do?What do they do?

Supply O2 and nutrients to myocardiumSupply O2 and nutrients to myocardium Approximately 200 ml blood/min @ restApproximately 200 ml blood/min @ rest

Where do they originate?Where do they originate? Sinus of Sinus of ValsavaValsava Coronary Coronary OstiumOstium

Sinus of ValsalvaSinus of Valsalva

InnervationInnervation: : VagusVagus NerveNerve Senses Pressure ChangesSenses Pressure Changes

Afferent: Send signals to vasomotor center in brain stemAfferent: Send signals to vasomotor center in brain stem Increase in Increase in intraaorticintraaortic pressure pressure ----> reflex > reflex bradycardiabradycardia & &

decreased SVRdecreased SVR Decrease in Decrease in intraaorticintraaortic pressure increases HR & vascular pressure increases HR & vascular

resistanceresistance

Coronary ArteriesCoronary Arteries RCARCA

MarginalMarginal LCA (left main)LCA (left main)

LADLAD DiagonalDiagonal

CircumflexCircumflex MarginalMarginal

Anterior HeartAnterior Heart

RCA: supplies RA, RV, part of inferior / posterior surface of LV, 1/3 septum55% SA node, 90% AV node

LAD: supplies Anterior wall of LV, 2/3 septum, Bundle of His

Diastole = fillingDiastole = filling

Posterior HeartPosterior Heart

Circumflex: supplies Lateral and Posterior LV & part of RVAnastomosesCollateral circulation

AngioscopyAngioscopy

1

2

LCx, stable angina

Smooth white plaque, no thrombus

LAD, angina Braunwald IIIB

Disrupted yellow plaque,red and white thrombus

Rupture of the heart complicates acute MI in about Rupture of the heart complicates acute MI in about 10% of cases10% of cases

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AMI LocalizationAMI Localization

aVF inferiorIII inferior V3 anterior V6 lateral

aVL lateralII inferior V2 septal V5 lateral

aVRI lateral V1 septal V4 anterior

Heart Chambers and ValvesHeart Chambers and Valves Chambers (4)Chambers (4)

2 2 atrialatrial 2 ventricles2 ventricles

Right thin walledRight thin walled Left thick wallLeft thick wall

SeptumSeptum AtrialAtrial VentricularVentricular

ValvesValves AV = tricuspid and mitral (S1)AV = tricuspid and mitral (S1) SL = SL = pulmonicpulmonic and aortic (S2)and aortic (S2)

Papillary MusclesPapillary Muscles Anchors AV to ventriclesAnchors AV to ventricles

ChordaeChordae TendineaeTendineae Keep cusps from inverting into Keep cusps from inverting into

atria when closedatria when closed

Blood Flow Blood Flow

CirculationCirculation

Superior & Inferior vena cava and coronary sinus Superior & Inferior vena cava and coronary sinus →→ RtRt atrium atrium →→tricuspid valve tricuspid valve →→ RtRt ventricle ventricle →→ pulmonicpulmonic valve valve →→pulmonary artery pulmonary artery →→ lungs lungs →→ pulmonary veins pulmonary veins →→ Lt atrium Lt atrium →→mitralmitral valve valve →→Lt ventricle Lt ventricle →→aortic valve aortic valve →→ aorta and aorta and coronary arteriescoronary arteries

http://www.youtube.com/watch?v=gIXcWE0bTwY

Peripheral CirculationPeripheral Circulation ArteriesArteries

ArteriolesArterioles LayersLayers

Tunica Tunica intimaintima (inner)(inner) Tunica media (middle) = constriction and dilationTunica media (middle) = constriction and dilation Tunica adventitia (outer)Tunica adventitia (outer)

VeinsVeins VenulesVenules ValvesValves

Keep blood flow one wayKeep blood flow one way CapillariesCapillaries

O2 / CO2 exchangeO2 / CO2 exchange Venous = low pressureVenous = low pressure Arterial = high pressureArterial = high pressure

AV AV anastomosesanastomoses (AV Shunts)(AV Shunts)

Asymptomatic, Intermediate Asymptomatic, Intermediate Lesions Cause Most Lesions Cause Most MIsMIs

shear stressshear stressplaque instabilityplaque instability

vasoconstrictionvasoconstrictionthrombosisthrombosis

asymptomaticasymptomatic

MI/SCDMI/SCD

PhysiologyPhysiology

PumpPump Low pressure = RightLow pressure = Right

Supplies Pulmonary Supplies Pulmonary bedbed

High pressure = LeftHigh pressure = Left Supplies systemic bedSupplies systemic bed

Right side and left sideRight side and left side Atria contract Atria contract Ventricles contractVentricles contract

Contraction Contraction Ventricular contractionVentricular contraction

SystoleSystole 0.28 sec0.28 sec

Ventricular relaxationVentricular relaxation DiastoleDiastole 0.52 sec0.52 sec

One Cardiac CycleOne Cardiac Cycle

Isovolumetric ContractionIsovolumetric Contraction

4 valves (closed)

The LV must generate enough pressure toovercome Aortic Enddiastolic Pressure (AEDP) to push the Aortic Valveopen

90% MVO2 Occurs

Ventricular EjectionVentricular Ejection

Isovolumetric RelaxationIsovolumetric Relaxation

No shifts in volume No shifts in volume in ventriclesin ventricles

Atria may fill Atria may fill No No atrialatrial or or

ventricular ventricular contractioncontraction

All 4 valves closedAll 4 valves closed

Diastole = filling Diastole = filling

Valves in ActionValves in Action

Measurement of Measurement of Cardiac PerformanceCardiac Performance

Myocardial Oxygen Myocardial Oxygen

SupplySupply Coronary artery Coronary artery

anatomyanatomy Diastolic pressure Diastolic pressure Diastolic timeDiastolic time OO22 extractionextraction

HBGHBG PaOPaO22

DemandDemand HRHR AfterloadAfterload PreloadPreload ContractilityContractility

MVO2

Myocardial Oxygen is dependent on Coronary Art Perfusion-90% occurs during diastole-Normal Cardiac O2 extraction is 75 – 80% of O2 Available

Electrophysiology Electrophysiology Cardiac Cell CharacteristicsCardiac Cell Characteristics

ExcitabilityExcitability ConductivityConductivity ContractilityContractility AutomaticityAutomaticity

Certain heart cells have the ability to undergo spontaneous Certain heart cells have the ability to undergo spontaneous depolarizationdepolarization Action potential is generated without influence from nearby Action potential is generated without influence from nearby

cells cells Primary pacemaker cellsPrimary pacemaker cells Dependent on ionic charge within the cellDependent on ionic charge within the cell

Depolarization / Depolarization / repolarizationrepolarization Action potentialAction potential

Action PotentialAction Potential

Ions + Action PotentialIons + Action Potential Phase 4 Phase 4

Resting membrane potentialResting membrane potential Phase 0Phase 0

QRSQRS Rapid DepolarizationRapid Depolarization Upstroke (rapid = V max)Upstroke (rapid = V max) Fast Na + channels open = Na + moves inFast Na + channels open = Na + moves in

Phase 1Phase 1 QRSQRS Fast Na channels close (+40 mV)Fast Na channels close (+40 mV) K+ and K+ and ClCl –– out (slow)out (slow)

Phase 2Phase 2 ST SegmentST Segment Plateau phasePlateau phase Ca Channel opens = Ca+ moves in Ca Channel opens = Ca+ moves in K+ moves out (slow)K+ moves out (slow)

Phase 3Phase 3 TT--WaveWave Ca+ channels closeCa+ channels close More K+ channels open= K+ moves inMore K+ channels open= K+ moves in

Phase 4Phase 4 ((--90mV)90mV)

http://www.youtube.com/watch?v=_bmp2_T0c7k

Refractory PeriodRefractory Period

Acidosis reduces Na and Ca channels conductivities. Acidosis reduces Na and Ca channels conductivities. Compared with Compared with hyperkalemiahyperkalemia the action potential duration is further decreased the action potential duration is further decreased

due to shortening of the plateau phase (reduced Ca conductance).due to shortening of the plateau phase (reduced Ca conductance). AP upAP up--stroke amplitude decays due to Na channels increased resistance.stroke amplitude decays due to Na channels increased resistance.

Electrical Pathway Electrical Pathway Cardiac Conductive Cardiac Conductive

SystemSystem ComponentsComponents

SinoatrialSinoatrial NodeNode InternodalInternodal AtrialAtrial

PathwaysPathways AtrioventricularAtrioventricular

NodeNode AtrioventricularAtrioventricular

JunctionJunction Bundle of HisBundle of His Left and Right Left and Right

Bundle BranchesBundle Branches Purkinje FibersPurkinje Fibers

Each possess their Each possess their own intrinsic rateown intrinsic rate Each slower than Each slower than

the pacer the pacer precedingpreceding

Electrical ConductionElectrical Conductionhttp://www.youtube.com/watch?v=06iQlVMSB34

Systole and DiastoleSystole and Diastole

Electrophysiologic representation:Electrophysiologic representation:

What does each part of the complex mean?What does each part of the complex mean?

In ReviewIn Review

Intrinsic Rates

Sinus node 60 to 100 times a minute

Atrioventricular node 40 to 60 times a minute

Purkinje fibers 15 to 40 times a minute

AntiarrhythmicsAntiarrhythmics Class 1 Class 1

Na channel blockersNa channel blockers Class 2Class 2

AntiAnti--sympatheticsympathetic beta blockersbeta blockers

Class 3Class 3 Potassium channel Potassium channel

blockersblockers Class 4Class 4

Affect the AV nodeAffect the AV node Calcium Channel blockersCalcium Channel blockers

Class 5Class 5 miscellaneousmiscellaneous Adenosine Adenosine -- DigoxinDigoxin

Nervous System ControlNervous System Control ParasympatheticParasympathetic

VagusVagus nerve nerve ––CholinergicCholinergic

BRAKESBRAKES slow HRslow HR Slow conduction Slow conduction

implulseimplulse VasovagalVasovagal maneuversmaneuvers

SympatheticSympathetic Atria and ventriclesAtria and ventricles Adrenergic = Adrenergic =

CatecholamineCatecholamine VasocontrictionVasocontriction Change in stroke Change in stroke

volumevolume ACCELERATORACCELERATOR

Increase HRIncrease HR Increase automaticityIncrease automaticity Increase AV conductionIncrease AV conduction Increase contractilityIncrease contractility

BaroreceptorsBaroreceptors

ChemoreceptorChemoreceptor

Cardiac AuscultationCardiac Auscultation MitralMitral

55thth ICS Left of MCLICS Left of MCL TricuspidTricuspid

44thth ICS Left of ICS Left of sternumsternum

AorticAortic 22ndnd ICS Right of ICS Right of

sternumsternum PulmonicPulmonic

22ndnd ICS Left of ICS Left of sternumsternum

Erb’sErb’s PointPoint 33rdrd ICS Left of ICS Left of

sternumsternum