Determinants of Cardiac Determinants of Cardiac OutputOutput

Intro to Tele

Leslie Binder MSN, RN

Heart FactsHeart Facts

The adult heart pumps The adult heart pumps about 5 quarts of blood about 5 quarts of blood each minute - approximately each minute - approximately 2,000 gallons of blood each 2,000 gallons of blood each day - throughout the body. day - throughout the body.

The heart beats about The heart beats about 100,000 times each day. 100,000 times each day.

In a 70-year lifetime, the In a 70-year lifetime, the average human heart beats average human heart beats more than 2.5 billion times.more than 2.5 billion times.

Cardiac AnatomyCardiac Anatomy

Goal of the HeartGoal of the Heart

Main goal of the heart is to get blood Main goal of the heart is to get blood and oxygen to organs and body and oxygen to organs and body tissues.tissues.

HemodynamicsHemodynamics Study of the Study of the

movement and movement and forces of blood forces of blood within the within the cardiovascular cardiovascular system (chambers system (chambers & great vessels)& great vessels)

Often monitored Often monitored via the use of via the use of invasive lines and invasive lines and accompanying accompanying equipmentequipment

Can be obtained Can be obtained using direct and using direct and indirect measuresindirect measures

Why is understanding hemodynamics so important?

Hemodynamics will help you evaluate the effectiveness of your patients cardiac function.

Indications for Indications for Hemodynamic MonitoringHemodynamic Monitoring

Decreased cardiac Decreased cardiac outputoutput

HypovolemiaHypovolemia HemorrhageHemorrhage GI bleedGI bleed BurnsBurns Shock (Cardiogenic, Shock (Cardiogenic,

Septic, Neurogenic)Septic, Neurogenic) Post SurgeryPost Surgery Acute MIAcute MI CardiomyopathyCardiomyopathy Congestive Heart Congestive Heart

FailureFailure

Methods of Obtaining Methods of Obtaining Hemodynamic Hemodynamic MeasurementsMeasurements

Heart Rate

Methods of Obtaining Methods of Obtaining Hemodynamic Hemodynamic MeasurementsMeasurements

Non Invasive Blood Pressure Non Invasive Blood Pressure MonitoringMonitoring Dinamap Manual

Method Doppler

Invasive Methods of Invasive Methods of Obtaining Hemodynamic Obtaining Hemodynamic

MeasurementsMeasurementsArterial Line

Invasive Methods of Invasive Methods of Obtaining Hemodynamic Obtaining Hemodynamic

MeasurementsMeasurements Pulmonary ArteryPulmonary Artery

Catheter (PA Catheter)Catheter (PA Catheter)

Signs of Inadequate Signs of Inadequate PerfusionPerfusion

Factors Influencing Factors Influencing Cardiac FunctionCardiac Function

Autonomic Autonomic Nervous SystemNervous System

Renin-Angiotensin Renin-Angiotensin SystemSystem

ElectrolytesElectrolytes Diseases and or Diseases and or

abnormalities of abnormalities of the circulatory the circulatory systemsystem

Autonomic Nervous Autonomic Nervous SystemSystem

Internal regulating system Internal regulating system that maintains homeostasis that maintains homeostasis within the body.within the body.

Composed of a network of Composed of a network of nerves that send signals to nerves that send signals to the heart and other organs.the heart and other organs.

Divided into Divided into Parasympathetic and Parasympathetic and Sympathetic Nervous Sympathetic Nervous System.System.

Baroreceptors play a role in Baroreceptors play a role in blood pressure regulation.blood pressure regulation.

Baroreceptors and Chronic Baroreceptors and Chronic HypertensionHypertension

Do not drop BP too low too fast especially in those with chronic hypertension.

Autonomic Nervous System

Renin-Angiotensin Renin-Angiotensin SystemSystem

(ARB)

Medications that affect Medications that affect the RAS the RAS

Beta BlockersBeta Blockers Angiotensin Angiotensin

converting enzyme converting enzyme inhibitors (ACE inhibitors (ACE ihibitors)ihibitors)

Angiotensin receptor Angiotensin receptor blockersblockers

Aldosterone blockadeAldosterone blockade Direct Renin Direct Renin

InhibitorsInhibitors

Role of Electrolytes in Role of Electrolytes in HemodynamcisHemodynamcis

Electrolytes play a Electrolytes play a major role in heart major role in heart muscle functionmuscle function

PotassiumPotassium MagnesiumMagnesium CalciumCalcium

Example of diseases that affect cardiac function:

Cardiomyopathies

Diseases of the Circulatory Diseases of the Circulatory System that Affect System that Affect

HemodynamicsHemodynamics Atrial FibrillationAtrial Fibrillation Aortic StenosisAortic Stenosis BradycardiaBradycardia Cardiac TamponadeCardiac Tamponade Heart BlocksHeart Blocks Myocardial InfarctionMyocardial Infarction Supraventricular TachycardiasSupraventricular Tachycardias Ventricular ArrhythmiasVentricular Arrhythmias

Basic Hemodynamic Basic Hemodynamic TerminologyTerminology

Heart RateHeart Rate Cardiac OutputCardiac Output Stroke VolumeStroke Volume PreloadPreload Afterload Afterload ContractilityContractility Mean Arterial PressureMean Arterial Pressure Ejection FractionEjection Fraction Cardiac IndexCardiac Index

Heart RateHeart Rate

Factors Affecting Heart Factors Affecting Heart RateRate

Causes of Rapid Heart Rate

Medications That Increase Medications That Increase Heart RateHeart Rate

Meds that Meds that increase increase Heart RateHeart Rate AtropineAtropine EpinepherineEpinepherine Dopamine (2-Dopamine (2-

10mcg/kg/mi10mcg/kg/min)n)

PacemakerPacemaker

Causes of LowCauses of Low Heart Rate Heart Rate

Medications that Lower Medications that Lower Heart RateHeart Rate

Adenosine

Beta Blockers

Digoxin

Calcium Channel Blockers

Cardiac OutputCardiac Output

CO= HR x SVCO= HR x SV

Example:Example: Heart Rate 100bpmHeart Rate 100bpm Stroke Volume 50mL/beatStroke Volume 50mL/beat CO=5,000 mL per min or 5 L/minCO=5,000 mL per min or 5 L/min Normal CO is 4-6 L/minNormal CO is 4-6 L/min

Factors Causing Factors Causing Low Cardiac OutputLow Cardiac Output

Inadequate Left Inadequate Left Ventricular Filling Ventricular Filling TachycardiaTachycardia Rhythm disturbanceRhythm disturbance HypovolemiaHypovolemia Mitral or Tricuspid StenosisMitral or Tricuspid Stenosis Pulmonic StenosisPulmonic Stenosis Constrictive Pericarditis or Constrictive Pericarditis or

TamponadeTamponade Restrictive CardiomyopathyRestrictive Cardiomyopathy

Factors Causing Factors Causing Low Cardiac OutputLow Cardiac Output

Inadequate Left Ventricular EjectionInadequate Left Ventricular Ejection Coronary Artery Disease causing LV Coronary Artery Disease causing LV

ischemia or infarctionischemia or infarction Myocarditis or cardiomyopathyMyocarditis or cardiomyopathy HypertensionHypertension Aortic StenosisAortic Stenosis Mitral RegurgitationMitral Regurgitation Drugs that are negative inotropesDrugs that are negative inotropes Metabolic disordersMetabolic disorders

High Cardiac OutputHigh Cardiac Output

Healthy patientHealthy patient CO ↑ secondary to CO ↑ secondary to

increased 02 increased 02 demand (exercise, demand (exercise, fear, anxiety).fear, anxiety).

In hospitalIn hospital Response to Response to

systemic systemic inflammation inflammation (Sepsis).(Sepsis).

Stroke VolumeStroke Volume Stroke VolumeStroke Volume

Volume of blood ejected Volume of blood ejected from each ventricle with from each ventricle with each heartbeateach heartbeat

Normal 50-100 mL per beatNormal 50-100 mL per beat Decreased SV= increased HRDecreased SV= increased HR

Determinants of Stroke Volume

Preload Afterload Contractility

PreloadPreload

Stretch of the Stretch of the ventricular wallventricular wall

Usually related Usually related to volumeto volume

Frank Starlings Frank Starlings Law:Law:

How full is the How full is the tank?tank?

PreloadPreload

Factors affecting Factors affecting preload:preload: Absolute blood Absolute blood

volumevolume Distribution of blood Distribution of blood

in bodyin body Atrial kickAtrial kick Ventricular functionVentricular function Ventricular Ventricular

compliancecompliance

Conditions Conditions Affecting PreloadAffecting Preload

Increased Preload seen in:Increased Preload seen in: Increased circulating volume/hypervolemiaIncreased circulating volume/hypervolemia Mitral insufficiencyMitral insufficiency Aortic insufficiencyAortic insufficiency Heart FailureHeart Failure

Decreased Preload seen in:Decreased Preload seen in: Decreased circulating volume (bleeding, third Decreased circulating volume (bleeding, third

spacing)spacing) Mitral stenosisMitral stenosis Vasodilator use (NTG)Vasodilator use (NTG) Asynchrony of atria and ventriclesAsynchrony of atria and ventricles Cardiac tamponadeCardiac tamponade Atrial FibAtrial Fib

Interventions Interventions Affecting Preload Affecting Preload

To Increase PreloadTo Increase Preload Fluids (0.9% NS, LR)Fluids (0.9% NS, LR) Vasopressors (only Vasopressors (only

effective if tank is “full”)effective if tank is “full”) Blood and or blood Blood and or blood

productsproducts Volume expandersVolume expanders

Decrease PreloadDecrease Preload DiureticsDiuretics

Lasix, AldactoneLasix, Aldactone Vasodilators such as Vasodilators such as

nitrates, Morphinenitrates, Morphine

AfterloadAfterload The resistance or The resistance or

pressure which the pressure which the ventricle must overcome ventricle must overcome to eject its volume of to eject its volume of blood during blood during contraction.contraction.

Right VentricleRight Ventricle Pulmonary Vascular Pulmonary Vascular

Resistance (PVR)Resistance (PVR) Left VentricleLeft Ventricle

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

Factors Factors Affecting Affecting AfterloadAfterload

Ventricular outflow Ventricular outflow obstructionobstruction Aortic valve stenosisAortic valve stenosis

Sympathetic NS Sympathetic NS stimulation stimulation epinephrine releasedepinephrine released

increased PVRincreased PVR HTNHTN Hypercoagulability Hypercoagulability

Interventions to Increase Interventions to Increase Afterload Afterload

To Increase Afterload:To Increase Afterload: Give Vasoconstrictors/VasopressorsGive Vasoconstrictors/Vasopressors

Dopamine (↑contractility,↑02 consumption)Dopamine (↑contractility,↑02 consumption) DobutamineDobutamine Epinepherine- vasoconstrictor, ↑HREpinepherine- vasoconstrictor, ↑HR NorepinepherineNorepinepherine

Be sure to correct hypovolemia with Be sure to correct hypovolemia with volume replacement before volume replacement before considering vasopressors.considering vasopressors.

Interventions to Decrease Interventions to Decrease Afterload Afterload

To Decrease Afterload:To Decrease Afterload: VasodilatorsVasodilators Arterial Dilators: Arterial Dilators:

Morphine, Morphine, Nitroprusside, Nitroprusside, Hydralazine, Clonidine, Hydralazine, Clonidine, Labetelol, Ace Labetelol, Ace Inhibitors, ARBsInhibitors, ARBs

Intra Aortic Balloon Intra Aortic Balloon Pump (IABP)Pump (IABP)

ContractilityContractility Refers to the inherent Refers to the inherent

ability of the ability of the myocardium to myocardium to contract normally. contract normally. Contractility is Contractility is influenced by preload.influenced by preload.

Affected by:Affected by: Ventricular muscle massVentricular muscle mass Heart RateHeart Rate Oxygen statusOxygen status Chemical or Chemical or

pharmacological effectspharmacological effects

Conditions That Increase Conditions That Increase ContractilityContractility

Sympathetic StimulationSympathetic Stimulation Fear or anxietyFear or anxiety

CalciumCalcium

InotropesInotropes DigitalisDigitalis MilrinoneMilrinone EpinepherineEpinepherine DobutamineDobutamine

Conditions That Decrease Conditions That Decrease ContractilityContractility

Negative InotropesNegative Inotropes Beta Blockers, Calcium Beta Blockers, Calcium

Channel Blockers, Channel Blockers, barbituates and most barbituates and most antidysrythmics.antidysrythmics.

InfarctionInfarction CardiomyopathyCardiomyopathy Vagal StimulationVagal Stimulation HypoxemiaHypoxemia AcidosisAcidosis

How it’s all relatedHow it’s all related

Cardiac Output

Heart Rate Stroke Volume

Preload Afterload ContractilityUsually set by

SA node

Mean Arterial PressureMean Arterial Pressure

MAP is considered to be the MAP is considered to be the perfusion pressure seen by the perfusion pressure seen by the organs in the body.organs in the body.

Goal = MAP > 60mm/Hg Goal = MAP > 60mm/Hg <60 leads to ischemia<60 leads to ischemia Calculated MAP= Calculated MAP= 2 x Dialstolic 2 x Dialstolic

+Systolic+Systolic 33

Pulse PressurePulse Pressure

Difference between systolic and Difference between systolic and diastolic pressuresdiastolic pressures Representative of Stroke Volume and Representative of Stroke Volume and

arterial capacitancearterial capacitance Normal range 30-40mm/HgNormal range 30-40mm/Hg Changes in pulse pressure can indicate Changes in pulse pressure can indicate

certain conditions (exercise, shock, certain conditions (exercise, shock, heart failure).heart failure).

Cardiac IndexCardiac Index

CI = CO/BSACI = CO/BSANormal range for CI is 2.5-4.0 Normal range for CI is 2.5-4.0

L/min/m²L/min/m²

Ejection FractionEjection Fraction The amount of blood The amount of blood

estimated to be estimated to be pumped out of the LV pumped out of the LV to the rest of the body to the rest of the body with each heartbeat. with each heartbeat.

Normal range is 50- Normal range is 50- 75%.75%.

Systolic dysfunction Systolic dysfunction occurs when EF falls occurs when EF falls below 50%.below 50%.

Measured by Measured by echocardiogram, echocardiogram, nuclear study, MRI, nuclear study, MRI, CT.CT.

Assessment Findings in Assessment Findings in Compromised Compromised

HemodynamicsHemodynamics Drop in BPDrop in BP Rapid weak pulsesRapid weak pulses Change in LOCChange in LOC Cold, mottled, cyanotic skinCold, mottled, cyanotic skin TachycardiaTachycardia TachypneaTachypnea Complaints of lightheadedness Complaints of lightheadedness Decreased urine outputDecreased urine output HypoxiaHypoxia EdemaEdema

Nursing ConsiderationsNursing ConsiderationsKnow your patient’s baseline blood pressure.Know your patient’s baseline blood pressure.

Rapid heart rates lead to more oxygen Rapid heart rates lead to more oxygen consumed.consumed.

To decrease workload of the heart consider To decrease workload of the heart consider grouping patient activities throughout the grouping patient activities throughout the shift. shift.

Use caution when lowering blood pressure Use caution when lowering blood pressure too rapidly in patients with chronic HTN.too rapidly in patients with chronic HTN.

In states of low perfusion or low BP, body In states of low perfusion or low BP, body compensates by increasing heart rate.compensates by increasing heart rate.

ConclusionConclusion