Nadine has taught nursing for 12 years and has a PhD in Nursing research
Cardiac Preload: Definition & Reduction
What Is Cardiac Preload?
Cardiac preload is the pressure of the blood on the muscle fibers in the ventricles of the heart at the end of diastole. It is actually measured as an estimate, representing the amount of blood volume in the left ventricle of the heart at that particular point in the cardiac cycle, just before the heart contracts and when it is filled with the most blood, which is the end of diastole.

An error occurred trying to load this video.
Try refreshing the page, or contact customer support.
You must cCreate an account to continue watching
Register to view this lesson
As a member, you'll also get unlimited access to over 84,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.
Get unlimited access to over 84,000 lessons.
Try it nowAlready registered? Log in here for access
BackYou're on a roll. Keep up the good work!
Just checking in. Are you still watching?
Yes! Keep playing.The Heart & Cardiac Preload
First let's talk about the heart, one of the most important muscles in the body. It's made up of fibers that expand and contract in order to fill and empty the blood in the heart chambers. There are four chambers in the heart, two atria and two ventricles. The atria are pathways for the blood received by the body to go into the ventricles, and the ventricles contract, during which time they pump the blood out into the body.
![]() |
Preload is one of the four heart functions that make up cardiac output, or the amount of blood ejected from the heart per minute.
The other functions constitute afterload, the resistance the ventricle needs to overcome to eject blood, contractility, the force of the contraction, and heart rate, also known as the pulse, or the number of beats per minute.
There are two types of cardiac preload: left ventricular preload and right ventricular preload. Measurement of left ventricular preload is recorded as pulmonary arterial wedge pressure (PAWP). Normal PAWP ranges between 6 and 12 millimeters of mercury (mmHg). Measurement of right ventricular preload is recorded as right arterial pressure (RAP). Normal levels of RAP range from 2 to 7 mmHg.
Alteration in Preload Volumes
At this point in the lesson, it is important to know that the heart pumps out all the blood it receives from the body. So how does cardiac preload fit into this discussion? Well, if the blood returned to the atria from the body has more volume than normal, the result is increased preload. This means that the heart pumps out to the body all the blood it receives, so the cardiac muscle is stretched to accommodate the blood. The stretched ventricular muscle contracts with greater force to pump out all the blood. One example of when someone may experience increased cardiac preload is during an illness involving pulmonary or lung congestion. Pulmonary congestion can be measured by PAWP. A PAWP value of greater than 20 mmHg shows moderate congestion in the lungs. At 30 mmHg or greater, one is diagnosed with acute pulmonary edema.
So, what happens when there is less volume of blood returned to the atria from the body? That is called decreased preload, and as expected, the ventricle has less blood to pump out to the body, so decreased contraction of the ventricle occurs. Conditions that cause reduced preload include those where there is less circulating blood volume. A few of those conditions include blood loss from any reason, like injury or surgery, decreased return of blood to the heart, pooling of the blood in the legs, or a blood clot.
Lesson Summary
Cardiac preload happens at the end of diastole before the ventricles contract. It represents the amount of pressure exerted on the ventricles by the volume of blood. Increased preload produces greater contraction of the ventricles to pump the increased volume of blood to the body. Decreased preload produces reduced contraction of the ventricles.
Normal cardiac preload in the left ventricle is measured by PAWP, or pulmonary arterial wedge pressure, ranging between 6 and 12 mmHg. A left ventricle preload is measured by a left arterial pressure, or PAWP, of 30 mmHg or greater. Right ventricle preload is measured by right arterial pressure, or RAP, and the normal levels range from 2 to 7 mmHg.
To unlock this lesson you must be a Study.com Member.
Create your account
Register to view this lesson
Unlock Your Education
See for yourself why 30 million people use Study.com
Become a Study.com member and start learning now.
Become a MemberAlready a member? Log In
BackCardiac Preload: Definition & Reduction
Related Study Materials
- Pathophysiology Syllabus Resource & Lesson Plans
- Mental Health Study Guide
- Mitosis: Help & Review
- Neuroanatomy: Help & Tutorials
- AP Physics 2 Textbook
- AP Physics 2: Homeschool Curriculum
- AP Physics 1: Homeschool Curriculum
- AP Physics C: Homeschool Curriculum
- AP Physics C Textbook
- Nutrition 101 Curriculum Resource & Lesson Plans
- NY Regents Exam - Chemistry: Help and Review
- Glencoe Earth Science: Online Textbook Help
- Holt Chemistry: Online Textbook Help
- High School Biology Curriculum Resource & Lesson Plans
- SAT Chemistry: Help and Review
Browse by Courses
- Aspartate Transaminase (AST): Definition, Function & Structure
- What is the Binding Constant?
- What is Bradykinin? - Definition, Structure & Formation
- Bradykinin: Function, Effects & Inhibitors
- Cross-Linked Enzyme Aggregates: Immobilization & Applications
- What is Enzyme Biocatalysis? - Definition, Examples & Applications
- Types of Biocatalysis: Industrial & Applied
- Buccal Cavity: Definition, Structure & Function
- Ectopic Calcification: Definition, Symptoms & Treatment
- Syncytium: Definition & Function
- Peroxisomal Disorders: Symptoms & Treatment
- Peroxisomal Disorders: Definition & Diagnosis
- Astrocytes: Definition, Function & Types
- What is Allostasis? - Definition, Allostatic Load & Example
- Allostasis vs. Homeostasis: Differences & Relationship
Browse by Lessons
- Computer Science: Help and Review
- General History Lessons
- General Science Lessons
- TExES Science of Teaching Reading (293): Practice & Study Guide
- Next Gen NCLEX-PN Study Guide & Practice
- Musical Instrument Instruction
- Choral Instruction
- Curriculum & Assessment in Music Education
- Strategies for Music Instruction
- Introduction to War
- How to Pass the CDA Test
- What is the CDA Test?
- IAAP CAP Test Day Preparation
- ILTS Test Score Information
- IAAP CAP Registration Information
- IAAP CAP Test Retake Policy
- IAAP CAP Test Score Information
Latest Courses
- Role of the Skin in Homeostasis & Immunity
- Hijab: Definition and Relation to Islam
- Primary Source: The Treaty of Paris
- Ammit: Mythology, Hieroglyphics & Facts
- Foreign Tax Credits for Businesses: Eligibility & Deductability
- One Day When I Was Lost Summary
- Veterinary Plan of Action for Primates
- Quiz & Worksheet - Porfiry Petrovich in Crime and Punishment
- Quiz & Worksheet - What is RNA Editing?
- Quiz & Worksheet - Reconciling Subledger & General Ledger for Accounts Payable & Accrued Liabilities
- Quiz & Worksheet - Positions, Planes & Cavities Terms in Anatomy
- Flashcards - Real Estate Marketing Basics
- Flashcards - Promotional Marketing in Real Estate
- Parts of Speech Worksheets
- Cyberbullying Facts & Resources for Teachers
Latest Lessons
- Technical Writing: Help and Review
- Anatomy and Physiology: Certificate Program
- Intro to Music for Teachers: Professional Development
- High School Psychology Syllabus Resource & Lesson Plans
- Middle School Earth Science: Help and Review
- World Wars & Unrest
- AP Chemistry: Phase Changes for Liquids and Solids: Help and Review
- Quiz & Worksheet - Types of Problems & Problem Solving Strategies
- Quiz & Worksheet - Literature & Art in the American Romantic Period
- Quiz & Worksheet - Finding the Greatest Common Factor
- Quiz & Worksheet - Ingroups vs. Outgroups
- Quiz & Worksheet - Enlightened Despotism in France, Austria & Prussia
Popular Courses
- Effects of Inflation on Suppliers and Demanders
- Best Practices for Writing Agile User Stories
- First Grade Word Walls: List & Activities
- Georgia Alternative Teacher Certification
- Best IT Certifications
- How to See If Your School Accepts Study.com Credit
- Wisconsin Science Standards for 4th Grade
- Texas Teacher Certification Test Limit Waiver
- Sequencing Activities for 5th Grade
- Wisconsin State Teaching Standards
- 5th Grade Math Centers
- What to Do When You're Rejected from All Colleges
Popular Lessons
Math
Social Sciences
Science
Business
Humanities
Education
History
Art and Design
Tech and Engineering
- Tech and Engineering - Videos
- Tech and Engineering - Quizzes
- Tech and Engineering - Questions & Answers
Health and Medicine
- What is the purpose of adding 40% NaOH solution to the tin reduction mixture ?
- Describe the factors that oppose left ventricular ejection. Provide clinical examples.
- In terms of cardiac action, what does Q-T interval represent?
- The stretching of myocardium of the ventricles during ventricular diastole is referred to as _______. a. preload b. stroke volume c. afterload. d. end-systole volume. e. contractility.
- What does the term preload refer to? a. volume of venous return b. peripheral resistance c. stroke volume d. cardiac output
- The force of contraction of the cardiac muscle is affected by: A. muscle fiber length at the start of a contraction. B. contractility of the heart. C. the end-diastolic volume. D. amount of blood entering the heart. E. All of the above.
- Karen is taking the medication Verapamil, a drug that blocks the calcium channels in cardiac muscle cells. What effect should this medication have on Karen's cardiac output? Why?
- The degree of stretch experienced by the sarcomeres in the ventricle cells before the contract is called: A) afterload. B) contractility. C) stroke volume. D) preload
- Answer true or false: Preload is the amount of blood in the ventricles right before they begin to contract.
- Briefly define the following terms: a. Preload b. Afterload c. Starling's law of the Heart
Explore our library of over 84,000 lessons
- Create a Goal
- Create custom courses
- Get your questions answered