Cardiovascular System John P. McDonough, CRNA, Ed.D., ARNP

Cardiovascular SystemCardiovascular System

John P. McDonough,John P. McDonough, CRNA, Ed.D., ARNPCRNA, Ed.D., ARNP

VesselsVessels

ArteriesArteries– carry blood away from the heartcarry blood away from the heart

» oxygenated (except PA)oxygenated (except PA)

VeinsVeins– carry blood to the heartcarry blood to the heart

» desaturated (except PV)desaturated (except PV)

CapillariesCapillaries– local circulationlocal circulation– connects arteries to veinsconnects arteries to veins

““Great” VesselsGreat” Vessels

Vena cavaVena cava– superior & inferiorsuperior & inferior

Pulmonary arteryPulmonary artery Pulmonary veinPulmonary vein AortaAorta

Blood Flow Through the HeartBlood Flow Through the Heart

Rt AtriumRt Atrium Tricuspid valveTricuspid valve Rt ventricleRt ventricle Pulmonic valvePulmonic valve Lt atriumLt atrium Mitral valveMitral valve Lt ventricleLt ventricle Aortic valveAortic valve

Structure of the HeartStructure of the Heart

PericardiumPericardium– visceralvisceral– parietalparietal– pericardial fluidpericardial fluid

MyocardiumMyocardium– contractile heart musclecontractile heart muscle

EndocardiumEndocardium– cavity lining cavity lining

Circulation to the Heart ItselfCirculation to the Heart Itself

Lt main coronary arteryLt main coronary artery– Lt anterior descending Lt anterior descending – Lt circumflexLt circumflex

Rt coronary arteryRt coronary artery Coronary perfusionCoronary perfusion

– occurs during diastole occurs during diastole – rate changes effect rate changes effect diastolediastole onlyonly

Cardiac Conduction SystemCardiac Conduction System(electrical (electrical mechanical function) mechanical function)

Sinoatrial (AS) nodeSinoatrial (AS) node– ““pacemaker of the heart”pacemaker of the heart”

Intra-atrial conduction pathwaysIntra-atrial conduction pathways Atrioventricular (AV) nodeAtrioventricular (AV) node Bundle of HisBundle of His Rt bundle branchRt bundle branch Lt bundle branchLt bundle branch

– Lt anterior & posterior faciclesLt anterior & posterior facicles

Circulatory SystemCirculatory System 2 separate circuits, serially connected2 separate circuits, serially connected Output of one Output of one the input of the other the input of the other

– pulmonary, systemicpulmonary, systemic Heart is functions as 2 pumpsHeart is functions as 2 pumps

– Rt = pulmonary, Lt = systemicRt = pulmonary, Lt = systemic ArteriesArteries VeinsVeins CapillariesCapillaries

Adrenergic Control of Heart RateAdrenergic Control of Heart Rate

-adrenergic receptors (generally dilates -adrenergic receptors (generally dilates & excites)& excites) 11 found mostly in the heart (conduction found mostly in the heart (conduction

system)system) 22 found mostly in the lungs (bronchi), but also found mostly in the lungs (bronchi), but also

in the coronary arteriolesin the coronary arterioles

Adrenergic Control of Heart RateAdrenergic Control of Heart Rate

-adrenergic stimulation will -adrenergic stimulation will heart rate & heart rate & dilate bronchidilate bronchi

-adrenergic blockade will -adrenergic blockade will heart rate & heart rate & constrict bronchiconstrict bronchi

Norepinephrine binds with Norepinephrine binds with 1 1 receptorsreceptors

Epinephrine binds with Epinephrine binds with 22 receptors receptors

Adrenergic Control of Heart RateAdrenergic Control of Heart Rate

-adrenergic receptors -adrenergic receptors – some in the heart, but mostly in vesselssome in the heart, but mostly in vessels

Stimulation causes constrictionStimulation causes constriction

Autonomic Control of Heart Autonomic Control of Heart RateRate

SympatheticSympathetic– thoracic chain ganglia thoracic chain ganglia – neurotransmitter = norepinephrine (NE) neurotransmitter = norepinephrine (NE)

parasympatheticparasympathetic– vagus nerve (CN-X)vagus nerve (CN-X)– neurotransmitter = acetylcholine (Ach)neurotransmitter = acetylcholine (Ach)

Other Controls of Heart RateOther Controls of Heart Rate

Volume controlVolume control– Barinbridge reflexBarinbridge reflex

Pressure controlPressure control– baroreceptorsbaroreceptors

Factors Effecting Cardiac OutputFactors Effecting Cardiac Output

PreloadPreload AfterloadAfterload Heart RateHeart Rate ContractilityContractility

1, 300, 000 Myocardial 1, 300, 000 Myocardial Infarctions yearly in the Infarctions yearly in the

United StatesUnited States

50% are fatal50% are fatal

Risk Factors for CV DiseaseRisk Factors for CV Disease

SmokingSmoking Diabetes mellitusDiabetes mellitus HypertensionHypertension HyperlipidemiaHyperlipidemia

Risk Factors for CV Disease Risk Factors for CV Disease (con’t)(con’t)

Genetic predisposition Genetic predisposition ObesityObesity Sedentary life-styleSedentary life-style Type A personality Type A personality

HypertensionHypertension

50 million Americans have it50 million Americans have it Diagnosed if >2 B/P measurements show:Diagnosed if >2 B/P measurements show:

– diastolic readings >90diastolic readings >90– average of 2 systolic >140average of 2 systolic >140

Mortality rates:Mortality rates:– white women white women 4.7%4.7%– white menwhite men 6.3%6.3%– black womenblack women 29.3%29.3%– black menblack men 22.5%22.5%

Determinants of Hypertension Determinants of Hypertension

Essential hypertensionEssential hypertension– stressstress– dietdiet– genetic factorsgenetic factors

Secondary hypertensionSecondary hypertension– pheochromocytomapheochromocytoma– renal vascular diseaserenal vascular disease– Cushing’s syndromeCushing’s syndrome– thyrotoxicosisthyrotoxicosis

Effect of Vessel DiameterEffect of Vessel Diameter

With the same 100mg/Hg pressure driving:With the same 100mg/Hg pressure driving:– d=1 d=1 1 ml/min 1 ml/min– d=2 d=2 16 ml/min 16 ml/min– d=3 d=3 256 ml/min 256 ml/min

Complications of HypertensionComplications of Hypertension

Myocardial ischemiaMyocardial ischemia Ventricular failureVentricular failure Pulmonary edemaPulmonary edema Aortic dissectionAortic dissection Intracerebral hemorrhageIntracerebral hemorrhage

Common AntihypertensivesCommon Antihypertensives

Beta BlockersPropanolol, esmolol,metoprolol, atenolol

Blocks effect ofcate. at receptors.Decreases HR &CO

Orthostatichypotension

ACE InhibitorsCaptopril, enalapril,

Dec conversion ofAT-1 To AT-2

Bronchospasm,bradycardia,hypotension

CalciumantagonistsNifedipine, diltiazem

Inhibits Ca++uptake, decperipheralresistance

Reflex tach,hypotension

Cardiomyopathies Cardiomyopathies

Primary disorders of the muscle itself Primary disorders of the muscle itself – not related to CAD, HTN or valve disordersnot related to CAD, HTN or valve disorders

Dilated cardiomyopathyDilated cardiomyopathy– toxins, ETOH, infection, nutrition,toxins, ETOH, infection, nutrition,

Hypertrophic cardiomyopathy Hypertrophic cardiomyopathy – usually congenital usually congenital

Restrictive cardiomyopathyRestrictive cardiomyopathy– usually infiltrative disease processusually infiltrative disease process

Congestive Heart FailureCongestive Heart Failure(a (a symptom symptom complex)complex)

Each side of the heart can fail separately Each side of the heart can fail separately Left HF is a frequent cause of right HFLeft HF is a frequent cause of right HF

– frequent, but the not the onlyfrequent, but the not the only S/S Left heart failureS/S Left heart failure

– dyspneadyspnea– pulmonary congestionpulmonary congestion

S/S Right heart failureS/S Right heart failure– peripheral edemaperipheral edema– vein distentionvein distention

Treatment of CHFTreatment of CHF

Rate controlRate control Digitalis glycosides (lanoxin)Digitalis glycosides (lanoxin) DiureticsDiuretics Phosphodiesterase (PDE) inhibitorsPhosphodiesterase (PDE) inhibitors

Cardiac muscle extracts the largest amount of Cardiac muscle extracts the largest amount of oxygen because of the extensive work the heart oxygen because of the extensive work the heart

does (manifested as contractility) even during rest.does (manifested as contractility) even during rest.At rest: 8-10 ml OAt rest: 8-10 ml O22/min/100g of myocardium./min/100g of myocardium.

During exercise this can increase by a factor of 10.During exercise this can increase by a factor of 10.

But what drives the contraction But what drives the contraction process in myocytes?process in myocytes?

Answer: ATPAnswer: ATP

As demand goes up, inotropic response of the As demand goes up, inotropic response of the heart increases and the coronary vasculature heart increases and the coronary vasculature adapts by vasodilating to provide an adequate adapts by vasodilating to provide an adequate oxygen supply.oxygen supply.

If, due to atherosclerotic disease, the coronary If, due to atherosclerotic disease, the coronary arteries are unable to sustain the myocardium, arteries are unable to sustain the myocardium, ischemia ensues and the flow is predicted by:ischemia ensues and the flow is predicted by:

Q = Q = P rP r44/ 8 n L/ 8 n Lwhere r is radius of vessel, n is viscosity and L is vessel length.where r is radius of vessel, n is viscosity and L is vessel length.

Factors in Supply & DemandFactors in Supply & Demand

Decreased supplyDecreased supply– reduced contentreduced content

– reduced coronary flowreduced coronary flow

– increased LV pressureincreased LV pressure

– fixed vascular fixed vascular obstructionobstruction

Increased demandIncreased demand– positive chronotropismpositive chronotropism

– positive inotropismpositive inotropism

– increased LV volumeincreased LV volume

– increased wall tensionincreased wall tension

– increased afterloadincreased afterload

Visualization of intracellular oxygenation:Microspectrophotometry

Reference: Takahashi, E. and K. Doi. Visualization of oxygen level inside a single cardiac myocyte. Am. J. Physiol. 268: H2561-H2568, 1995.

Aerobic environmentHappy myocytes

Anoxic environmentMyocytes not happy

HistoryHistory PainPain DyspneaDyspnea PalpitationPalpitation EdemaEdema SyncopeSyncope Fatigue & Fatigue &

WeaknessWeakness CyanosisCyanosis

Hemodynamic to Formulae Hemodynamic to Formulae

BP = CO x SVRBP = CO x SVR CO = SV x HRCO = SV x HR SV = LVEDV - LVESVSV = LVEDV - LVESV SVR = MAP - CVP x 80 / COSVR = MAP - CVP x 80 / CO

– normal = 800-1200 dyne/sec/cmnormal = 800-1200 dyne/sec/cm-5-5

Congestive Heart Failure Congestive Heart Failure (diagnostic problems)(diagnostic problems)

Volume overloadVolume overload BronchospasmBronchospasm PneumoniaPneumonia Pulmonary embolismPulmonary embolism Ischemically mediated pulmonary edemaIschemically mediated pulmonary edema

Characteristics of Chest PainCharacteristics of Chest Pain

ANGINAANGINA– retrosternal, diffuseretrosternal, diffuse

– Lt arm, jaw, backLt arm, jaw, back

– aching, dull, pressing, aching, dull, pressing, squeezing,squeezing,

– minutesminutes

– effort, emotion, eating effort, emotion, eating coldcold

– rest, NTGrest, NTG

PROBABLY NOTPROBABLY NOT– Lt inframam, localizedLt inframam, localized

– Rt armRt arm

– sharp, cutting, sharp, cutting, shooting, shooting,

– seconds, hours, daysseconds, hours, days

– respiration, posture, respiration, posture, motionmotion

– nonspecificnonspecific

Cardiac Causes of Chest PainCardiac Causes of Chest Pain

CADCAD aortic valve diseaseaortic valve disease pulmonary pulmonary

hypertensionhypertension

mitral valve prolapsemitral valve prolapse pericarditispericarditis IHSSIHSS

Pulmonary Causes of Chest PainPulmonary Causes of Chest Pain

pulmonary embolismpulmonary embolism pneumoniapneumonia pleuritispleuritis pneumothoraxpneumothorax

Musculoskeletal Causes of Chest Musculoskeletal Causes of Chest PainPain

costochondritiscostochondritis arthritisarthritis muscular spasmmuscular spasm bone tumorbone tumor

GI Causes of Chest PainGI Causes of Chest Pain

ulcer diseaseulcer disease bowel diseasebowel disease hiatal herniahiatal hernia pancreatitispancreatitis cholecystitischolecystitis

Other Causes of Chest PainOther Causes of Chest Pain

VascularVascular– aortic dissectionaortic dissection

EmotionalEmotional– anxietyanxiety– despressiondespression

Common Causes of PalpitationsCommon Causes of Palpitations

extrasystolesextrasystoles tachyarrthymiastachyarrthymias bradyarrthymiasbradyarrthymias drugsdrugs

smokingsmoking caffeinecaffeine thyrotoxicosisthyrotoxicosis

Common Causes of DyspneaCommon Causes of Dyspnea

CardiacCardiac– Lt failureLt failure

– mitral stenosismitral stenosis

PulmonaryPulmonary– obstructive diseaseobstructive disease

– asthmaasthma

– restrictive diseaserestrictive disease

– pulmonary HTNpulmonary HTN

EmotionalEmotional High altitude exposureHigh altitude exposure AnemiaAnemia

Physical Exam of the HeartPhysical Exam of the Heart

inspectioninspection blood pressure blood pressure assess arterial pulseassess arterial pulse assess JV pulseassess JV pulse

percussion percussion palpationpalpation auscultationauscultation evaluation of edemaevaluation of edema

Murmur DescriptionMurmur Description

timing in cycletiming in cycle locationlocation radiationradiation durationduration intensityintensity

pitchpitch qualityquality relationship to relationship to

positionposition relationship to relationship to

respirationrespiration

Grading of Murmurs (I-V/VI)Grading of Murmurs (I-V/VI)

I lowest intensityI lowest intensity II low intensityII low intensity III medium intensity (without thrill)III medium intensity (without thrill) IV medium intensity (with thrill)IV medium intensity (with thrill) V loudest murmur with scope on chestV loudest murmur with scope on chest VI loudest, heard with scope off chestVI loudest, heard with scope off chest

Location of Murmurs within Cardiac Cycle

“Shape” of Murmurs

Three Most Three Most Important Survival Important Survival

FactorsFactors MYOCARDIAL PRESERVATIONMYOCARDIAL PRESERVATION MYOCARDIAL PRESERVATIONMYOCARDIAL PRESERVATION MYOCARDIAL PRESERVATIONMYOCARDIAL PRESERVATION

““Dead meat don’t beat!”Dead meat don’t beat!”