Member Information
Get Connected
Reading/Career
Search by Category
 Medical Alert Devices
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 



Medical-Alert-Devices.com

Home Search by Zip US Directory Contact Members Login Register Open Jobs

Post articles View all articles Print article

Ventricular Fibrillation


Ventricular fibrillation (V-fib or VF) is a cardiac condition that consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart that eventually leads to the heart stopping altogether.



Ventricular fibrillation (V-fib or VF) is a cardiac condition that consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart that eventually leads to the heart stopping altogether.

 

Introduction

Ventricular fibrillation is considered a medical emergency. If the arrhythmia continues for more than a few seconds, blood circulation will cease, as evidenced by lack of pulse, blood pressure and respiration, and death will occur.

 

Ventricular fibrillation is a cause of cardiac arrest and sudden cardiac death. The ventricular muscle twitches randomly, rather than contracting in unison, and so the ventricles fail to pump blood into the arteries and into systemic circulation. Ventricular fibrillation is a sudden lethal arrhythmia responsible for many deaths in the Western world, mostly brought on by ischemic heart disease. Despite much work, the underlying nature of fibrillation is not completely understood. Most episodes of fibrillation occur in diseased hearts, however others occur in so-called normal hearts. Much work still has to be done to elucidate the mechanisms of ventricular fibrillation.

 

Treatment

The condition can often be reversed by the electric discharge of DC current from a defibrillator. Antiarrhythmic agents like amiodarone or lidocaine can help, but, unlike atrial fibrillation, VF rarely reverses spontaneously in large adult mammals. Although a defibrillator is designed to correct the problem, and its effects can be dramatic, it is not always successful.

 

In patients at high risk of ventricular fibrillation the use of an implantable cardioverter defibrillator has been shown to be beneficial.

 

Re-entry

The role of re-entry or circus motion was demonstrated separately by Mines and Garrey [Mines GR 1913, Garrey WE 1914]. Mines created a ring of excitable tissue by cutting the atria out of the ray fish. Garrey cut out a similar ring from the turtle ventricle. They were both able to show that, if a ring of excitable tissue were stimulated at a single point, the subsequent waves of depolarization would pass around the ring. The waves eventually meet and cancel each other out, but, if an area of transient block occurred with a refractory period that blocked one wavefront and subsequently allowed the other to proceed retrogradely over the other path, then a self-sustaining circus movement phenomenon would result. For this to happen, however, it is necessary that there be some form of non-uniformity. In practice, this may be an area of ischemic or infarcted myocardium, or underlying scar tissue.

 

It is possible to think of the advancing wave of depolarization as a dipole with a head and a tail. The length of the refractory period and the time taken for the dipole to travel a certain distance - the propagation velocity - will determine whether such a circumstance will arise for re-entry to occur. Factors that promote re-entry would include a slow-propagation velocity, a short refractory period with a sufficient size of ring of conduction tissue. These would enable a dipole to reach an area that had been refractory and is now able to be depolarized with continuation of the wavefront.

 

In clinical practice, therefore, factors that would lead to the right conditions to favour such re-entry mechanisms include increased heart size through hypertrophy or dilatation, drugs which alter the length of the refractory period and areas of cardiac disease. Therefore, the substrate of ventricular fibrillation is transient or permanent conduction block. Block due either to areas of damaged or refractory tissue leads to areas of myocardium for initiation and perpetuation of fibrillation through the phenomenon of re-entry.

 


 

All text of this article available under the terms of the GNU Free Documentation License (see Copyrights for details).

  
Medical Alert System Providers   Show All articles
Search by Zip
  Enter Zip  search
Contact Medical Alert System Providers near you.
Firstname *
Lastname *
Email *
Phone *
Alt. Phone
Zip *
Brief reason to contact *
Los Angeles Medical Alert System ProviderMIAMI-DADE Medical Alert System ProviderCook Medical Alert System Provider
SAINT LOUIS Medical Alert System ProviderHarris Medical Alert System ProviderMaricopa Medical Alert System Provider
Orange Medical Alert System ProviderSan Diego Medical Alert System ProviderPRINCE GEORGES Medical Alert System Provider
Kings Medical Alert System ProviderDade Medical Alert System ProviderQueens Medical Alert System Provider
Dallas Medical Alert System ProviderWayne Medical Alert System ProviderKing Medical Alert System Provider
San Bernardino Medical Alert System ProviderSanta Clara Medical Alert System ProviderDEKALB Medical Alert System Provider
Broward Medical Alert System ProviderDU PAGE Medical Alert System ProviderRiverside Medical Alert System Provider
New York Medical Alert System ProviderPhiladelphia Medical Alert System ProviderMiddlesex Medical Alert System Provider
Tarrant Medical Alert System ProviderAlameda Medical Alert System ProviderSuffolk Medical Alert System Provider
Cuyahoga Medical Alert System ProviderBexar Medical Alert System ProviderClark Medical Alert System Provider
 
More information...
A Guide To Medical Alerts
Medical alerts are devices that help the patient, to get adequate help of the right type during an emergency. They have become an acceptable and obligatory fashion accessory in the present day world....
Home Medical Alert Systems
Home medical alert systems are medical alert systems designed to help individuals and senior citizens who are often at home alone....
Buying Medical Alert Systems
It is advisable to buy a medical alert system before disaster strikes. Many people wait for an emergency to arise before buying a medical alert device....
Discount Medical Alert Systems
Medical alert systems are necessary in case of elderly people staying alone or in case of patients with problems such as heart disease, Alzheimers or asthma....
Medical Alert Bracelets for Diabetics
If you or someone you love has diabetes, getting a diabetic medical alert bracelet is imperative. Because of the nature of the condition, diabetics can have medical emergencies at any time....
Auto Medical Alert Systems
Auto medical alert systems are emergency response systems designed to overcome any life threatening situation. It is a small and non-intrusive device providing independence, security and fast response...
Electronic Medical Alert Systems
Electronic medical alert system is an emergency monitoring system for seniors and frail persons. It serves as an invaluable security and safety device for seniors living alone...
Emergency Medical Alert Systems
Emergency medical alert systems are designed to provide medical help in emergency situations. These are medical alert systems extremely helpful in situations that arise from injuries or illnesses...
Medical Alert Bracelets
Fashionable medical identification jewelry is a perfect solution for those who suffer from critical medical conditions like epilepsy, stroke, diabetes, heart transplant, fainting fits, asthma, memory ...
Medical Alert Services
Certain companies provide Medical Alert Services not only to senior citizens, but also to persons of all ages who suffer from critical medical conditions which may deteriorate suddenly and necessitate...
Medical Alert Wristwatches
Medical alerts are devices that have been responsible for saving quite a few lives. They are available in various types. Some of them are in the form of wristwatches that can be worn by the patient....
Medical Alert Cards
Almost everyone suffers from one form of malady or another. Besides, the strain of cutthroat work environments may make you vulnerable to nervous and even physical breakdowns....
Medical Alert ID
The information on the medical IDs saves the precious time taken for diagnosis and ensures timely treatment. Medical alert identifications are a sure shot way to get immediate treatment in emergency....
Medical Alert Alarm
Medical alert alarms are alarm systems that are used to summon immediate medical attention in emergency situations. ...
Medical Alert Tags
Medical alert tags are medical identification tags that contain important medical information of the person wearing it. ...
Medical Alert Jewelry
The medical information of the person such as drug allergies, food allergies, their prescribed medicines and even emergency phone numbers can be engraved on a medical alert jewelry...
How to choose a medical alert system?
A consumer best chooses a medical alert system depending on his particular situation, budget and needs. Choosing a medical Alert system for an emergency is not an easy task. ...
What are Medical Alert Systems?
They prove helpful during an in home emergency. These are electronic wireless devices worn on your body to alert friends, family and doctors in case of any medical emergency....
Medical Alert Products
Patients suffering from serious health conditions such as cardiac problems, severe allergies, diabetes, epilepsy and other chronic illness are in need of medical alert products. ...
Medical Alert Systems
Most of the alert systems are connected through your phone line and are similar to an answering machine. A typical medical alert system is a console that is equipped with a very loud speaker ...

Contact Us | Site Map | RSS Feeds | Articles | Jobs | All Members | Popular Searches | Popular Questions