Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Cardiac Cycle01:29

Cardiac Cycle

The cardiac cycle refers to the sequence of events that occur in the heart from the beginning of one heartbeat to the next. It's characterized by alternating periods of contraction (systole) and relaxation (diastole) of the heart muscles.
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Physiology of the Heart: The Cardiac Cycle01:18

Physiology of the Heart: The Cardiac Cycle

The cardiac cycle describes the events from one heartbeat to the next. It includes three main phases: diastole, atrial systole, and ventricular systole, all driven by changes in chamber pressures and the function of heart valves.
Diastole: The Relaxation Phase
During diastole, all four heart chambers relax. The atrioventricular (AV) valves open, and the semilunar valves close. This phase sees the lowest chamber pressures, promoting ventricular filling. Venous blood enters the heart through the...
The Cardiac Cycle01:13

The Cardiac Cycle

The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...
Cardiac Output I:Effect of Heart Rate on Cardiac Output01:19

Cardiac Output I:Effect of Heart Rate on Cardiac Output

Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

On-Chip Generation of Copolarized and Spectrally Separable Photon Pairs.

Physical review letters·2026
Same author

STK25 Inhibits Epithelial-Mesenchymal Transition and Metastasis via the TGF-β/SMAD2 Signaling Pathway in Colorectal Cancer.

FASEB journal : official publication of the Federation of American Societies for Experimental Biology·2026
Same author

Diagnostic Performance of Prespecified OCT Rules for Glaucomatous Optic Neuropathy in Nonpathologic Myopia.

JAMA ophthalmology·2026
Same author

Correction: Copy number amplification-induced overexpression of lncRNA LOC101927668 facilitates colorectal cancer progression by recruiting hnRNPD to disrupt RBM47/p53/p21 signaling.

Journal of experimental & clinical cancer research : CR·2026
Same author

A Graph Neural Network-Based Multispectral-View Learning Model for Diabetic Macular Ischemia Detection From Color Fundus Photographs.

Translational vision science & technology·2026
Same author

An AI-Based OCT System to Detect Diabetic Macular Edema: A Prospective Validation and Noninferiority Randomized Clinical Trial.

JAMA·2026

Related Experiment Video

Updated: May 20, 2026

Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies
12:28

Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies

Published on: March 12, 2022

Does retinal vascular geometry vary with cardiac cycle?

Hao Hao1, Muhammad B Sasongko, Tien Y Wong

  • 1School of Electrical and Computer Engineering, Royal Melbourne Institute of Technology (RMIT University), Melbourne, Australia.

Investigative Ophthalmology & Visual Science
|July 28, 2012
PubMed
Summary

Retinal vascular measurements show minimal changes during the cardiac cycle, except for individual vessel caliber. This finding is important for understanding retinal vascular geometry and systemic vascular diseases.

More Related Videos

Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography
07:23

Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography

Published on: March 26, 2020

Using Retinal Imaging to Study Dementia
09:17

Using Retinal Imaging to Study Dementia

Published on: November 6, 2017

Related Experiment Videos

Last Updated: May 20, 2026

Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies
12:28

Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies

Published on: March 12, 2022

Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography
07:23

Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography

Published on: March 26, 2020

Using Retinal Imaging to Study Dementia
09:17

Using Retinal Imaging to Study Dementia

Published on: November 6, 2017

Area of Science:

  • Ophthalmology
  • Cardiology
  • Biomedical Engineering

Background:

  • Retinal vascular parameters correlate with systemic vascular health.
  • Understanding physiological variations in retinal vasculature is crucial.

Purpose of the Study:

  • To investigate dynamic changes in retinal vascular measurements throughout the cardiac cycle.
  • To assess the impact of cardiac function on retinal vessel geometry.

Main Methods:

  • Electrocardiogram-synchronized fundus imaging in 15 healthy volunteers.
  • Semiautomated software analysis of retinal vessel caliber, tortuosity, branching angle, and length-diameter ratio (LDR).
  • Statistical analysis using repeated-measures ANOVAs to compare measurements at nine cardiac points.

Main Results:

  • Significant variations observed in individual arteriolar and venular caliber.
  • No significant variations found in summary measures like central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE).
  • Minimal variations (<4.1%) in tortuosity, branching angle, and LDR across the cardiac cycle.

Conclusions:

  • Clinically relevant retinal vascular measures (CRAE, CRVE, tortuosity, branching angle) exhibit minimal variation during the cardiac cycle.
  • Individual retinal vessel caliber shows significant dynamic changes linked to cardiac activity.
  • Findings suggest that while overall retinal vascular geometry is stable, individual vessel caliber is dynamic.