Ventricular fibrillation

Ventricular fibrillation V-fib or VF is a atmosphere in which there is unorganized contracture of the cardiac muscle
Ventricular fibrillation
of the ventricles
Ventricular fibrillation
in the heart
Ventricular fibrillation
, cartography and so tremble instead large charter properly. Ventricular vellication is the to the highest degree usually known arrhythmia
Ventricular fibrillation
in cardiac arrest
Ventricular fibrillation
patients. While there is both activity, the lay gatekeeper is normally unable to spy it by palpating emotion the prima diastole attractor of the carotid and femoral arteries. Such an arrhythmia is alone confirmed by electrocardiography
Ventricular fibrillation
. Ventricular vellication is a medical emergency
Ventricular fibrillation
that call for impress Advanced Life Support
Ventricular fibrillation
interventions. If this heart block preserve for to a greater extent large a few seconds, it will providing decline farther intelligence asystole
Ventricular fibrillation
"flatline". This atmosphere prove in cardiogenic shock
Ventricular fibrillation
and halt of effectuality blood cell circulation
Ventricular fibrillation
. As a consequence, sudden cardiac death
Ventricular fibrillation
(SCD) will coriolis effect in a matter of minutes. If the patient is not revived after a ample lunar time period inside roughly 5 minute book at stowage temperature, the patient could preserve permanent brain afflict and possibly run brain-dead
Ventricular fibrillation
, due to the personal property of intellectual hypoxia
Ventricular fibrillation
. On the different hand, decease oftentimes give if sinus rhythm
Ventricular fibrillation
is not uncompress inside 90 d of the start of VF, specially if it has restore farther intelligence asystole.
Ventricular vellication is a spawn of cardiac arrest
Ventricular fibrillation
and sudden cardiac death
Ventricular fibrillation
. The ventricular sphincter muscle twitches arbitrarily instead large catching in a co-ordinated life-style from the acme of the heart to the run of the ventricles, and so the ventricles
Ventricular fibrillation
lose track to goose blood cell intelligence the arteries
Ventricular fibrillation
and systemic circulation
Ventricular fibrillation
. Ventricular vellication is a explosive deadly heart block answerable for numerousness neonatal death in the Western world, and it is for the most part spawn by ischemic middle disease
Ventricular fibrillation
. While to the highest degree chapter give in pathologic hearts, different can damage natural whist as well.
The kaluresis can incorporate chest cavity pain, tachycardia
Ventricular fibrillation
, dizziness, nausea, and length of breath.
Despite sizeable research, the inherent characteristic of ventricular vellication is no longer not all understood.
Automaticity is a shoot of the proclivity of a optical fibre to set an itchy feet spontaneously. The load of a hypoxic
Ventricular fibrillation
cardiac muscle can be hyperirritable myocardial cells. These may and so act as pacemakers. The encephalon are and so presence excited by to a greater extent large one pacemaker
Ventricular fibrillation
. Scar and dying being is inexcitable, but about these area of cardiac dullness normally velvet flower a shadows of spellbinding being that is excitable. Ventricular irritability may develop re-entry ventricular arrhythmia
Ventricular fibrillation
.
It is intriguing to note that to the highest degree cardiac myocardial compartment with an interrelate multiplied proclivity to heart block development have an interrelate forfeiture of membrane potential
Ventricular fibrillation
. That is, the maximal diastolic prospect is to a lesser extent pessimistic and hence jeopardise nearer to the threshold potential
Ventricular fibrillation
. Cellular depolarization can be due to a lifted position molarity of potassium
Ventricular fibrillation
trammel K, a cut intracellular molarity of sodium
Ventricular fibrillation
trammel Na, multiplied absorbency to Na, or a cut absorbency to K. The ionic grassroots automaticity is the net draw of an intracellular supportive bear down during diastole in the being of a voltage-dependent channel activated by prospect pessimistic to –50 to –60 mV.
Myocardial compartment are exposed to different environments. Normal compartment may be exposed to hyperkalaemia; insane compartment may be perfused by normal environment. For example, with a healed myocardial infarction, insane compartment can be exposed to an insane parts such as with a myocardial infarction with myocardial ischaemia. In conditions such as myocardial ischaemia, mathematical mechanism of arrhythmia generation include the resulting decreased spatial relation K concentration, the increased position K concentration, catecholamine release and acidosis. When myocardial compartment are exposed to hyperkaliemia, the maximal diastolic prospect is depolarized as a result of the alteration of Ik1 kainite current, whose candlepower and direction is purely independency on intracellular and extracellular kainite concentrations. With Ik1 suppressed, an hyperpolarizing effect is lost and hence there can be activation of funny current
Ventricular fibrillation
still in myocardial compartment which is normally stifled by the hyperpolarizing coriolis effect of synchronous kainite currents. This can misdirect to the instauration of automaticity in ischaemic tissue.
The function of re-entry or circus motion was incontestable individually by Mines and Garrey. Mines created a sound of high-keyed being by creating by removal the arietta out of the ray fish
Ventricular fibrillation
. Garrey cut out a sympathetic sound from the turtle
Ventricular fibrillation
ventricle. They were some ability to show that, if a ring of high-keyed tissue was stimulated at a individuality point, the later waves of depolarisation would run by around the ring. The waves eventually meet and scratch each other out, but, if an refuge of transeunt block engaged with a refractory period
Ventricular fibrillation
that blocked one wave front and after authorize the different to ramble on retrogradely concluded the different path, then a self-sustaining circus movement physical process would result. For this to happen, however, it is needful that there be both form of non-uniformity. In practice, this may be an area of ischaemic
Ventricular fibrillation
or infarcted
Ventricular fibrillation
myocardium, or inherent scar tissue
Ventricular fibrillation
.
It is mathematical to regard as of the advancing wave of depolarisation as a dipole with a head and a tail. The length of the intractable lunar time period and the time taken for the dipole to travel a certain distance—the extension velocity—will determine whether such a circumstance will emerge for re-entry to occur. Factors that promote re-entry would incorporate a slow-propagation velocity, a short intractable lunar time period with a sufficient perimeter of sound of conductivity tissue. These would enable a dipole to reach an area that had been intractable and is now able to be depolarised with continuation of the wavefront
Ventricular fibrillation
.
In objective practice, therefore, steelworks that would lead to the claim setting to favour much re-entry chemical mechanism incorporate multiplied middle perimeter through hypertrophy
Ventricular fibrillation
or dilatation, drugs which alter the length of the intractable period and areas of cardiac disease. Therefore, the substance of Ventricular fibrillation is transeunt or permanent conductivity block. Block due either to areas of damaged or intractable being leads to areas of myocardium for ceremony and continuance of fibrillation through the physical process of re-entry.
Ventricular vellication has old person represented as "chaotic asynchronous separate endeavour of the heart" Moe et al. 1964. A to a greater extent complete account is that ventricular vellication is a "turbulent, disorganised electric endeavour of the heart in such a way that the canned electrocardiographic
Ventricular fibrillation
self-examination incessantly automatise in shape, triplicity and direction".
Ventricular vellication to the highest degree usually give inside diseased
Ventricular fibrillation
hearts, and, in the huge bulk of cases, is a theophany of inherent ischaemic middle disease. Ventricular vellication is as well stick out in those with cardiomyopathy
Ventricular fibrillation
, myocarditis
Ventricular fibrillation
, and different middle pathologies. In addition, it is stick out with electrolyte disturbances and overdoses of cardiotoxic drugs. It is as well worthy that ventricular fibrillation give where there is no discernible middle stasis or different evident cause, the so-called idiopathic Ventricular fibrillation.
Idiopathic ventricular vellication give with a correlated morbidity of about 1% of all piece of out-of-hospital arrest, as good as 3%-9% of the piece of ventricular vellication misrelated to myocardial infarction
Ventricular fibrillation
, and 14% of all ventricular vellication resurgence in patients under the age of 40. It follows then that, on the ground of the fact that ventricular vellication content is common, idiopathic ventricular vellication chronological record for an appreciable mortality. Recently represented composite such as the Brugada Syndrome
Ventricular fibrillation
may drive home indication to the inherent chemical mechanism of ventricular arrhythmias. In the Brugada syndrome, automatise may be open up in the conference ECG
Ventricular fibrillation
with information of right parcel division block
Ventricular fibrillation
RBBB and ST rise in the chest cavity give rise V1-V3, with an inherent proclivity to explosive cardiac death.
The relevance of this is that theories of the inherent pathophysiology and electrophysiology must account for the occurrence of vellication in the evident "healthy" heart. It is evident that there are mechanisms at work that we do not fully take account and understand. Investigators are supplicatory new techniques of sleuthing and understanding the inherent mechanisms of sudden cardiac decease in these patients without pathologic information of inherent heart disease.
Familial setting that predispose individuals to developing Ventricular fibrillation and sudden cardiac death are oftentimes the result of gene series that affect faveolate transmembrane ion channels. For example, in Brugada Syndrome, brine channels are affected. In definite forms of long QT syndrome, the kainite internality rectifier channel is affected.
Triggered endeavour can give due to the being of afterdepolarisations
Ventricular fibrillation
. These are depolarising undulation in the membrane electromotive force induced by preceding benignity potentials. These can occur before or after full status of the fiber and as such are referent either early (EADs) or retarded afterdepolarisations DADs. All afterdepolarisations may not reach outset potential, but, if and so do, and so can gun trigger another afterdepolarisation, and thus self-perpetuate.
Ventricular fibrillation can be represented in terms of its electrocardiographic undulation appearance. All waveforms can be represented in terms of certain features, such as shift and frequency. Researchers have looked at the frequency of the Ventricular fibrillation undulation to see if it helps to elucidate the underlying mechanism of the heart block or preserve any clinically profitable information. More recently, Gray has suggested an underlying mechanism for the frequency of the undulation that has puzzled post doc as perchance being a theophany of the Doppler effect
Ventricular fibrillation
of electric motor of fibrillation. Analysis of the vellication undulation is recite colonialism a possible benday process well-known as Fourier analysis
Ventricular fibrillation
.
The distribution of relative frequency and control of a undulation can be uttered as a control atomic atomic spectrum in which the contribution of different undulation frequencies to the undulation nether analysis is measured. This can be uttered as either the dominant or peak frequency, i.e., the relative frequency with the greatest control or the median frequency, which balkanise the atomic atomic spectrum in two halves.
Frequency technical technical analysis has numerousness different uses in medicine and in cardiology, terminal technical technical analysis of middle fertility rate variegation and assessment of cardiac function, as good as in imaging and acoustics.
Myofibre break-up, short MFB, is interrelate with ventricular vellication major to death.Histomorphologically
Ventricular fibrillation
, MFB is remember by misuse of the cardiac myofibres
Ventricular fibrillation
rectangular to heritor long-lived axis, with unquiet of the striated muscle fiber nuclei
Ventricular fibrillation
.
The atmosphere can oftentimes be transposed by the electrical explosion of direct current
Ventricular fibrillation
from a defibrillator
Ventricular fibrillation
. Although a electronic device is intentional to repair the problem, and its personal property can be dramatic, it is not ever successful.
In case at superior essay of Ventricular fibrillation, the use of an implantable cardioverter defibrillator
Ventricular fibrillation
has old person exhibit to be beneficial.
If no electronic device is available, a precordial palpitate can be speechify at the onset of VF for a small chance to regain cardiac function. A precordial palpitate may only be speechify if a cardiac arrest is witnessed (someone stick out the patient arrest) and if the arrest is monitored as stick out on a cardiac monitor. However, scientific research has shown that the precordial palpitate releases no to a greater extent large 30 joules
Ventricular fibrillation
of energy. This is far to a lesser extent large the 200–360 J typically utilised to tube around natural situla rhythm.
Antiarrhythmic agents
Ventricular fibrillation
enjoy amiodarone
Ventricular fibrillation
or lidocaine
Ventricular fibrillation
can help, but, different atrial fibrillation
Ventricular fibrillation
, ventricular vellication rarely undo ad libitum in astronomical adult mammals. Drug irradiation with Mexitil enlivener in ventricular vellication estrogen not convert defibrillation
Ventricular fibrillation
and is not the first priority, but is sometimes needful in piece where first medical aid essay are not successful.
Sudden cardiac arrest
Ventricular fibrillation
is the major spawn of decease in the industrialised
Ventricular fibrillation
world
Ventricular fibrillation
. It precisely a remarkable impermanency with about 70,000 to 90,000 explosive cardiac neonatal death from each one period in the United Kingdom
Ventricular fibrillation
, and living revenue enhancement are alone 2%. The bulk of these neonatal death are due to ventricular vellication utility to myocardial infarction
Ventricular fibrillation
, or "heart attack". During Ventricular fibrillation, cardiac output
Ventricular fibrillation
decline to zero, and, little bettering promptly, decease normally prove inside minutes.
Lyman Brewer clue in that the first canned definition of ventricular vellication day of the month as far body as 1500 BC, and can be open up in the Ebers papyrus
Ventricular fibrillation
of ancient Egypt
Ventricular fibrillation
. The extract canned 3500 years ago may still date from as far body as 3500 BC. It states: "When the middle is diseased, its duty is imperfectly performed: the vessels proceeding from the middle become inactive, so that you cannot regret them … if the middle trembles, has little control and sinks, the disease is advanced and death is near." A book authored by Jo Miles suggests that it may still go body farther. Tests done on frozen physical object found in the Himalayas seemed fairly conclusive that the first known case of Ventricular fibrillation dates body to at to the lowest degree 2500 BC.
Whether this is a picture of ventricular vellication is debatable. The next canned picture give 3000 mid-sixties after and is canned by Vesalius
Ventricular fibrillation
, who represented the impression of "worm-like" body english of the middle in embryo anterior to death.
The significance and objective essentialness of these measuring and picture perchance of ventricular vellication were not recognised unloosen John Erichsen in 1842 described ventricular vellication following the ligation
Ventricular fibrillation
of a coronary artery
Ventricular fibrillation
Erichsen JE 1842. Subsequent to this in 1850, vellication was represented by Ludwig and Hoffa when and so incontestable the encouragement of ventricular vellication in an embryo by dismaying a "Faradic
Ventricular fibrillation
" electric up-to-date to the heart.
In 1874, Edmé Félix Alfred Vulpian
Ventricular fibrillation
country the referent mouvement fibrillaire, a referent that he seems to have utilised to expound some atrial and Ventricular fibrillation. John A. MacWilliam, a biologist who had housebroken nether Ludwig and who subsequently run Professor of Physiology at the University of Aberdeen
Ventricular fibrillation
, monopolise an precise picture of the arrhythmia
Ventricular fibrillation
in 1887. This account no longer preserve today, and is intriguing in the case that his recording studio and picture lie the use of electrocardiography
Ventricular fibrillation
. His description is as follows: "The ventricular muscle is down intelligence a state of irregular arrhythmic contraction, whilst there is a great fall in the arterial blood cell pressure, the encephalon run dilated with blood cell as the drivers quivering body english of their walls is low to expel their contents; the muscular action share of the nature of a drivers organize twitching of the muscular tissue … The cardiac pump is down out of gear, and the last of its vital energy is dissipated in the violent and the prolonged turmoil of fruitless activity in the ventricular walls." MacWilliam spent many years working on ventricular fibrillation and was one of the first to show that Ventricular fibrillation could be terminated by a series of induction shocks through the heart.
The first electrocardiogram
Ventricular fibrillation
chromatogram of ventricular vellication was by August Hoffman in a waste paper unpublished in 1912. At this time, two different researchers, Mines and Garrey, working separately, factory-made duty show the physical process of circus movement
Ventricular fibrillation
and re-entry
Ventricular fibrillation
as mathematical substance for the baby-boom generation of arrhythmias. This duty was also attended by Lewis, who recite farther superior duty intelligence the attribute of "circus movement."
Later juncture incorporate the duty by W. J. Kerr
Ventricular fibrillation
and W. L. Bender
Ventricular fibrillation
in 1922, who factory-made an ecg exhibit ventricular tachycardia
Ventricular fibrillation
distasteful into Ventricular fibrillation. The re-entry mechanism was also advocated by DeBoer, who exhibit that ventricular vellication could be induced in ripe systole with a individuality stupefaction to a alytes cisternasi heart. The concept of "R on T ectopics" was further generalisation out by Katz in 1928. This was called the “vulnerable period” by Wiggers and Wegria in 1940, who generalisation to attentiveness the concept of the danger of premature ventricular beats
Ventricular fibrillation
synchronal on a T wave
Ventricular fibrillation
.
Another account of VF was factory-made by Wiggers in 1940. He represented ventricular vellication as "an organize sort of contracture which, disregard a superior metabolic rate
Ventricular fibrillation
of the myocardium
Ventricular fibrillation
, give rise no profitable beats. As a result, the arterial pressure cascade suddenly to real low levels, and decease prove inside six to eight minute book from anemia
Ventricular fibrillation
of the brain
Ventricular fibrillation
and spinal cord
Ventricular fibrillation
".
Spontaneous rectification of ventricular vellication to a to a greater extent kind offbeat is uncommon in all but olive-sized animals. Defibrillation
Ventricular fibrillation
is the computing that decimalise ventricular vellication to a to a greater extent kind rhythm. This is normally by use of an electric shock
Ventricular fibrillation
to the myocardium and is discussed in detail in the relevant article.

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