Basic HemodynamicsBasic Hemodynamics

Objectives

• The learner will be able to identify the

structures of the heart.

Right-side AnatomyRight-side Anatomy

• Vena cava• Right atrium• Tricuspid valve• Right ventricle• Pulmonic valve

Middle AnatomyMiddle Anatomy

• Pulmonary artery• Pulmonary

capillary• Pulmonary vein

Left-side AnatomyLeft-side Anatomy

• Left atrium• Mitral valve• Left ventricle• Aortic valve

ObjectivesObjectivesThe learner will be able to state the

definition ofbasic hemodynamic terms :• Stroke volume, stroke volume index• Ejection fraction• Cardiac output, cardiac index• Preload• Afterload• Contractility

Stroke Volume (SV)Stroke Volume (SV)Definition• The volume of blood ejected by the ventricle with each heartbeat.

Normal Value• 60-70 mL

Stroke Volume Index Stroke Volume Index (SVI)(SVI)

Definition• Stoke volume indexed to BSA

Formula• SI = Stroke Volume / Body Surface Area• SI = SV / BSA

Normal value• 25 – 45 mL / m2

Ejection FractionEjection Fraction

• EF = end diastolic volume – end systolic volume

end diastolic volume

• Normal range = 60-75% of end diastolic volume

Cardiac Output (CO)Cardiac Output (CO)

Definition The volume of blood ejected from the ventricle over 1 minute.

Formula CO = heart rate x stroke volume CO = HR x SV

Normal Value 4 - 6 Liters / min

Cardiac Index (CI)Cardiac Index (CI)

Definition CO indexed against body size

Formula CI = Cardiac Output / Body Surface Area CI = CO / BSA

Normal Value 2.5 - 4.0 Liters / min / m2

CO/ CICO/ CI

Causes :

MI Shock HR SV (-) inotropes

vascular resistance Cardiac tamponade Hypovolemia Valvular heart disease High PEEP

CO / CICO / CI

CausesCauses : Hypertension vascular resistance Pulmonary edema metabolic state Positive inotropes

Cardiac Output (CO)Cardiac Output (CO)

Myocardial OxygenMyocardial Oxygen

Heart RateHeart Rate

HR MVO2 demand

Preload

Definition• Volume in ventricle at

end diastole.

OR• Pressure exerted on

walls of ventricle at end diastole.

PreloadPreload

Clinical Significance• Represents fluid returning to heart• Also known as “filling pressure” preload, MVO2 demand

PreloadPreload

Measurement• Preload is assessed by measuring

the filling pressure of each ventricle.

• Right ventricle preload CVP• Left ventricle preload PAOP

AfterloadAfterloadDefinition Amount of pressure the ventricle must work against during systole to open the valve.

AfterloadAfterload

Clinical significanceClinical significance afterloadafterload work of the heartwork of the heart MVO2 demandMVO2 demand

AfterloadAfterload

Factors that increase afterload: Vasoconstriction Valvular stenosis blood volume

AfterloadAfterload

Factors that decrease afterloadFactors that decrease afterload VasodilationVasodilation

AfterloadAfterload

MeasurementMeasurement Afterload is assessed by measuring Afterload is assessed by measuring

thethe resistance in the ventricle duringresistance in the ventricle during systolic ejection.systolic ejection.

Right ventricle afterload PVR Left ventricle afterload SVR

Systemic Vascular Resistance Systemic Vascular Resistance (SVR)(SVR)

DefinitionDefinition The resistance the left ventricleThe resistance the left ventricle

must pump against to eject itsmust pump against to eject its

volumevolume

This resistance is created by theThis resistance is created by the

systemic arteries and arteriolessystemic arteries and arterioles

Systemic Vascular Resistance Systemic Vascular Resistance (SVR)(SVR)

Formula [ (MAP – CVP) / CO ] x 80

Normal Value 800-1200 dynes/sec/cm-5

Systemic Vascular Systemic Vascular Resistance (SVR)Resistance (SVR)

Clinical Significance SVR represents left ventricle

afterload SVR, MVO2 demand SVR, Cardiac Output SVR, Cardiac Output

Systemic Vascular Systemic Vascular Resistance (SVR)Resistance (SVR)

CausesCauses:: VasoconstrictionVasoconstriction Catacholamine releaseCatacholamine release HypertensionHypertension Cardiogenic shockCardiogenic shock Cardiac tamponadeCardiac tamponade

Systemic Vascular Resistance Systemic Vascular Resistance (SVR)(SVR)

Causes Causes :: VasodilationVasodilation Vasodilator therapyVasodilator therapy Septic shock (hyperdynamic)Septic shock (hyperdynamic)

Pulmonary Vascular Resistance Pulmonary Vascular Resistance (PVR)(PVR)

DefinitionDefinition The resistance the right ventricle The resistance the right ventricle

mustmust

pump against to eject its volumepump against to eject its volume

This resistance is created by theThis resistance is created by the

pulmonary arteries and arteriolespulmonary arteries and arterioles

Pulmonary Vascular Pulmonary Vascular Resistance (PVR)Resistance (PVR)

Formula [ (PAM – PAOP ) / CO ] x 80

Normal Value 100-250 dynes/sec/cm-5 Normally one sixth of SVR

Pulmonary Vascular Resistance Pulmonary Vascular Resistance (PVR)(PVR)

Clinical SignificanceClinical Significance PVR represents right ventricle PVR represents right ventricle

afterloadafterload

Pulmonary Vascular Pulmonary Vascular Resistance (PVR)Resistance (PVR)

Causes of Causes of PVRPVR Pulmonary vessel constriction due Pulmonary vessel constriction due

toto

PaO2PaO2

PaCO2PaCO2 Pulmonary embolusPulmonary embolus

Contractility

Definition The heart’s contractile force or muscle strength

ContractilityContractility

Factors that influence contractility: Starling’s Law Sympathetic nervous system Pharmacologic agents

Starling’s LawStarling’s Law

The force of ventricular ejection isThe force of ventricular ejection is

related torelated to :: The volume in the ventricle atThe volume in the ventricle at

enddiastolicenddiastolic

(preload).(preload). The amount of myocardial stretchThe amount of myocardial stretch

placed on the ventricle.placed on the ventricle.

Sympathetic Nervous Sympathetic Nervous SystemSystem

SNS fibers are found throughoutSNS fibers are found throughout

the atria and ventriclesthe atria and ventricles The most important regulatoryThe most important regulatory

factor for myocardial contractilityfactor for myocardial contractility

Pharmacologic agentsPharmacologic agents

Inotrope ino = strength tropy = enhancing

Positive inotrope = stronger contraction Negative inotrope = weaker contraction

Positive InotropesPositive Inotropes

digoxindigoxin epinephrineepinephrine dopamine (Intropin)dopamine (Intropin) dobutamine (Dobutrex)dobutamine (Dobutrex) inamrinone (Inocor)inamrinone (Inocor) milrinone (Primacor)milrinone (Primacor)

Negative InotropesNegative Inotropes

lopressorlopressor amiodarone (Cordarone)amiodarone (Cordarone) diltiazem (Cardizem)diltiazem (Cardizem) verapamil (Calan)verapamil (Calan) procainamide (Pronestyl)procainamide (Pronestyl)

Hemodynamic ProfilesHemodynamic Profiles