Basic Hemodynamic

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Basic Hemodynamics

Objectives The learner will be able to identify the structures of the heart.

Right-side Anatomy Vena cava Right atrium Tricuspid valve Right ventricle Pulmonic valve

Middle Anatomy Pulmonary artery Pulmonary capillary Pulmonary vein

Left-side Anatomy Left atrium Mitral valve Left ventricle Aortic valve

ObjectivesThe learner will be able to state the definition of basic hemodynamic terms : Stroke volume, stroke volume index Ejection fraction Cardiac output, cardiac index Preload Afterload Contractility

Stroke Volume (SV)Definition The volume of blood ejected by the ventricle with each heartbeat. Normal Value 60-70 mL

Stroke Volume Index (SVI)Definition Stoke volume indexed to BSA Formula SI = Stroke Volume / Body Surface Area SI = SV / BSA Normal value 25 45 mL / m2

Ejection Fraction EF = end diastolic volume end systolic volume end diastolic volume Normal range = 60-75% of end diastolic volume

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)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/ CICauses : MI Shock HR SV (-) inotropes vascular resistance Cardiac tamponade Hypovolemia Valvular heart disease High PEEP

CO / CICauses : Hypertension vascular resistance Pulmonary edema metabolic state Positive inotropes

Cardiac Output (CO)

Myocardial Oxygen

Heart Rate HR MVO2 demand

PreloadDefinition Volume in ventricle at end diastole.OR Pressure exerted on walls of ventricle at end diastole.

PreloadClinical Significance Represents fluid returning to heart Also known as filling pressure preload, MVO2 demand

PreloadMeasurement Preload is assessed by measuring the filling pressure of each ventricle. Right ventricle preload CVP Left ventricle preload PAOP

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

AfterloadClinical significance afterload work of the heart MVO2 demand

AfterloadFactors that increase afterload: Vasoconstriction Valvular stenosis blood volume

AfterloadFactors that decrease afterload Vasodilation

AfterloadMeasurement Afterload is assessed by measuring the resistance in the ventricle during systolic ejection. Right ventricle afterload PVR Left ventricle afterload SVR

Systemic Vascular Resistance (SVR)Definition The resistance the left ventricle must pump against to eject its volume This resistance is created by the systemic arteries and arterioles

Systemic Vascular Resistance (SVR)Formula [ (MAP CVP) / CO ] x 80 Normal Value 800-1200 dynes/sec/cm-5

Systemic Vascular Resistance (SVR)Clinical Significance SVR represents left ventricle afterload SVR, MVO2 demand SVR, Cardiac Output SVR, Cardiac Output

Systemic Vascular Resistance (SVR)Causes: Vasoconstriction Catacholamine release Hypertension Cardiogenic shock Cardiac tamponade

Systemic Vascular Resistance (SVR)Causes : Vasodilation Vasodilator therapy Septic shock (hyperdynamic)

Pulmonary Vascular Resistance (PVR)Definition The resistance the right ventricle must pump against to eject its volume

This resistance is created by the pulmonary arteries and arterioles

Pulmonary Vascular Resistance (PVR)Formula [ (PAM PAOP ) / CO ] x 80 Normal Value 100-250 dynes/sec/cm-5 Normally one sixth of SVR

Pulmonary Vascular Resistance (PVR)Clinical Significance PVR represents right ventricle afterload

Pulmonary Vascular Resistance (PVR)Causes of PVR Pulmonary vessel constriction due to PaO2 PaCO2 Pulmonary embolus

ContractilityDefinition The hearts contractile force or muscle strength

ContractilityFactors that influence contractility: Starlings Law Sympathetic nervous system Pharmacologic agents

Starlings LawThe force of ventricular ejection is related to : The volume in the ventricle at enddiastolic (preload). The amount of myocardial stretch placed on the ventricle.

Sympathetic Nervous System

SNS fibers are found throughout the atria and ventricles The most important regulatory factor for myocardial contractility

Pharmacologic agents Inotrope ino = strength tropy = enhancing Positive inotrope = stronger contraction Negative inotrope = weaker contraction

Positive Inotropes

digoxin epinephrine dopamine (Intropin) dobutamine (Dobutrex) inamrinone (Inocor) milrinone (Primacor)

Negative Inotropes

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

Hemodynamic Profiles