Christina L
Well-known member
This is something that was posted on a yahoo board that I am on for hypothyroidism and adrenal fatigue. I thought it was very interesting, although kind of hard for my "simple" mind to digest. It is talking about atrial fibrillation and irregular heartbeats and how the heart works.
Christina L
--------------------------------
Sponge in a Bucket
Every cell in the human heart is a potential pacemaker. Fortunately, only
one small area usually takes on that role for a lifetime. As an electric
pump we should really consider the heart in terms of a top half that takes
blood in, and a bottom half that pumps it out.
The Sinus Node, which is the dominant pacemaker, resides in the top part
of the heart. It works on the same principle as a sponge. When you drop a
sponge in a bucket it soaks up fluid until it reaches its threshold and can't
take in any more water. A heart's pacemaker soaks up electrolytes like
Sodium and Potassium. When it reaches its threshold it kicks the cell next
to it, which repeats the process, sucking up electrolytes and kicking cells
in sequence all over the top of the heart. The action causes the atrial
chambers to squeeze blood into the bottom half.
Then there is a pause in this sweeping electrical buzz at a gatekeeper
area situated between the top and bottom halves of the heart. This pause is
designed to allow the lower ventricles time to accept the blood from the top
and to fill. After this pause the gatekeeper (the A-V node) then lets the
electrical wave carry on down so the bottom half of the heart can start its
own electrical domino, effect and pump blood to the rest of the body. The
whole process only takes a second.
But why and how does the process repeat itself several times a minute so
blood is constantly flowing? Just as you would wring out a sponge to get it
back to its original state, the pacemaker (and all the cells that followed
the leader) wring themselves out using the energy supplied by oxygen and
calories. Then the heart gets ready for its next beat.
Fish out of water
But what happens if the supplier of oxygen and calories to the heart gets
clogged, such as in cases of coronary artery disease? Then the dominant
pacer may start to falter. And if the other cells in the top of the heart
don't get kicked into action after a few seconds, they may begin to compete
for the top job themselves.
Atrial Fibrillation describes a bunch of would-be pacemakers in the top
part of the heart discharging irregularly. The heart muscle simply
fibrillates and it can neither fill nor empty its chambers properly. It
looks like a fish flopping around aimlessly on dry land...it doesn't get
anywhere. Fortunately, gravity allows some of the blood, that gets back to
the heart by the action of bodily muscles (via the venous system), to fall
into the lower chambers. Because the ventricles are still working, most
people survive, but are keenly aware of irregular palpitations in the chest
and are often short of breath. The back-up of blood in the system may cause
congestive heart failure. In this situation, fluld has nowhere else to go
and usually ends up in the lungs or bodily tissues. The skin is often puffy
especially in dependent areas like the ankles.
Thanks goodness for the gatekeeper (the A-V node), for it stops most of
these chaotic impulses from ever reaching the lower half of the heart. If
they were all let through, the whole heart would be a useless mass of
rapidly beating jelly. As is, the A-V node only lets through an occasional
beat-albeit irregularly- allowing the Ventricles to at least have time to
fill and empty properly.
However, if the A-V node gets sick (also from coronary heart disease,
scarring, or other problems) it may not be able to hold back the
aforementioned flood of electrical activity. This sad scenario is
incompatible with life for it now allows ventricular fibrillation to occur,
and virtually no blood gets to the body. Ventricular fibrillation can only
be stopped by an immediate electrical shock. Defibrillation (the shock
paddles seen on all the ER TV dramas) usually stuns the erratic pacemakers
into "emptying their sponges" all at once in the hope that a single dominant
pacemaker will resume command of a normally beating system.
My heart's all aflutter
Sometimes, if the normal pacemaker is sick, only a few dominant cells
(rather than thousands in atrial fibrillation) will compete for the top job.
Atrial flutter means that these few cells kick each other repetitively in a
rapid sequence. On an Electrocardiogram, the activity has a sawtooth
appearance as pacers bounce their messages back and forth in a jousting
match which can never be won. However, even though there is a little more
regularity than with Fibrillation, this is still a potentially life
threatening situation. It all depends on the rapidity of these top chamber
rogues. If the impulses are rapid (usually in the neighborhood of 150
impulses a minute) survival once again depends on how many the gatekeeper
allows through to the life-sustaining ventricles.
In a hospital, if the doctors feel that the gatekeeper is letting too many
impulses through (eg. if the heart is beating more than 150 times per
minute) they may try to slow things down. One way is by massaging the neck
which causes a reflex slowing in some lucky people. Another way is to give
medicine which makes the holes in the electrical sponges smaller so they can't
soak up the electrolytes and saturate as fast. If all else falls, shock
treatment is still an option. The shock hurts but patients are usually
sedated and given a mild anaesthetic.
Extra beats
As people get older, the millions of sponge-like cells in the heart get
aggravated or wear out. Sometimes they get overexcitable and fire on their
own without waiting for the master pacemaker to cue them. This can happen in
any of the chambers and it results in extra beats called extrasystoles. For
many years doctors were very fearful of these extra beats because it was
felt that they inevitably caused all the other cells to go crazy, leading to
dangerous fibrillation. After all, it is well known that people don't die
from clogging of the arteries (heart attacks); they expire from sudden death
cardiac arrhythmias.
Over the past few years doctors have learned that extra beats are more
common than they thought. Huge numbers of "normal" asymptomatic volunteers
had cardiac monitoring for 24 hours at a time. Scientists found that 60
percent of what they considered the normal ("thin") population have a few
extra beats every day. Most people don't even realize these beats occur.
They often feel like a tickle in the throat or chest. Unfortunately, some
people are painfully aware of these skips and feel the heart
"flip-flopping. "
As long as there is no underlying clogging of the arteries or any other
serious damage from illness or infection, these beats are usually innocuous.
Or so it was thought.
What about us?
Over the past few years I have heard from many large people who experience
extra beats, and whose doctors have told them they have nothing to worry
about. The problem is that no one has ever surveyed or done proper research
on obese subjects. This is worrisome because any advice is anecdotal and
pure guesswork. I surveyed some so-called experts who have given me
conflicting advice. Some say the hearts of large people have been damaged by
fat infiltrating the electrical system (fat cardiomyopathy) causing serious
extra beats. Others usually point to sleep apnea as a cause. In a previous
article I described apnea as a condition whereby the large thick structures
in the neck and throat cause bouts of gasping and snoring during sleep. The
resultant lack of oxygen definitely causes extra beats or bouts of very
rapid beating in an effort for the body to at least get what little payload
is in the system quickiy to where it is needed.
The problem with this seemingly simple explanation of why large people get
irregular of fast rhythms, is that even when the apnea is corrected (or when
people have lost lots of weight and no longer require sleep apnea machines)
the extra beats seem to persist during the day. In this scenario sleep apnea
is not the problem. I am not satisfied with all of these explanations.
I am especially perturbed at the usual answer; "tell fat people to lose
weight and they will be better off." I know of many large people who lost
huge amounts of weight and their irregular heart beats often got worse. It
is well known that rapid dieting is deadly and many succumb to sudden death
from heart arrhythmias.
Christina L
--------------------------------
Sponge in a Bucket
Every cell in the human heart is a potential pacemaker. Fortunately, only
one small area usually takes on that role for a lifetime. As an electric
pump we should really consider the heart in terms of a top half that takes
blood in, and a bottom half that pumps it out.
The Sinus Node, which is the dominant pacemaker, resides in the top part
of the heart. It works on the same principle as a sponge. When you drop a
sponge in a bucket it soaks up fluid until it reaches its threshold and can't
take in any more water. A heart's pacemaker soaks up electrolytes like
Sodium and Potassium. When it reaches its threshold it kicks the cell next
to it, which repeats the process, sucking up electrolytes and kicking cells
in sequence all over the top of the heart. The action causes the atrial
chambers to squeeze blood into the bottom half.
Then there is a pause in this sweeping electrical buzz at a gatekeeper
area situated between the top and bottom halves of the heart. This pause is
designed to allow the lower ventricles time to accept the blood from the top
and to fill. After this pause the gatekeeper (the A-V node) then lets the
electrical wave carry on down so the bottom half of the heart can start its
own electrical domino, effect and pump blood to the rest of the body. The
whole process only takes a second.
But why and how does the process repeat itself several times a minute so
blood is constantly flowing? Just as you would wring out a sponge to get it
back to its original state, the pacemaker (and all the cells that followed
the leader) wring themselves out using the energy supplied by oxygen and
calories. Then the heart gets ready for its next beat.
Fish out of water
But what happens if the supplier of oxygen and calories to the heart gets
clogged, such as in cases of coronary artery disease? Then the dominant
pacer may start to falter. And if the other cells in the top of the heart
don't get kicked into action after a few seconds, they may begin to compete
for the top job themselves.
Atrial Fibrillation describes a bunch of would-be pacemakers in the top
part of the heart discharging irregularly. The heart muscle simply
fibrillates and it can neither fill nor empty its chambers properly. It
looks like a fish flopping around aimlessly on dry land...it doesn't get
anywhere. Fortunately, gravity allows some of the blood, that gets back to
the heart by the action of bodily muscles (via the venous system), to fall
into the lower chambers. Because the ventricles are still working, most
people survive, but are keenly aware of irregular palpitations in the chest
and are often short of breath. The back-up of blood in the system may cause
congestive heart failure. In this situation, fluld has nowhere else to go
and usually ends up in the lungs or bodily tissues. The skin is often puffy
especially in dependent areas like the ankles.
Thanks goodness for the gatekeeper (the A-V node), for it stops most of
these chaotic impulses from ever reaching the lower half of the heart. If
they were all let through, the whole heart would be a useless mass of
rapidly beating jelly. As is, the A-V node only lets through an occasional
beat-albeit irregularly- allowing the Ventricles to at least have time to
fill and empty properly.
However, if the A-V node gets sick (also from coronary heart disease,
scarring, or other problems) it may not be able to hold back the
aforementioned flood of electrical activity. This sad scenario is
incompatible with life for it now allows ventricular fibrillation to occur,
and virtually no blood gets to the body. Ventricular fibrillation can only
be stopped by an immediate electrical shock. Defibrillation (the shock
paddles seen on all the ER TV dramas) usually stuns the erratic pacemakers
into "emptying their sponges" all at once in the hope that a single dominant
pacemaker will resume command of a normally beating system.
My heart's all aflutter
Sometimes, if the normal pacemaker is sick, only a few dominant cells
(rather than thousands in atrial fibrillation) will compete for the top job.
Atrial flutter means that these few cells kick each other repetitively in a
rapid sequence. On an Electrocardiogram, the activity has a sawtooth
appearance as pacers bounce their messages back and forth in a jousting
match which can never be won. However, even though there is a little more
regularity than with Fibrillation, this is still a potentially life
threatening situation. It all depends on the rapidity of these top chamber
rogues. If the impulses are rapid (usually in the neighborhood of 150
impulses a minute) survival once again depends on how many the gatekeeper
allows through to the life-sustaining ventricles.
In a hospital, if the doctors feel that the gatekeeper is letting too many
impulses through (eg. if the heart is beating more than 150 times per
minute) they may try to slow things down. One way is by massaging the neck
which causes a reflex slowing in some lucky people. Another way is to give
medicine which makes the holes in the electrical sponges smaller so they can't
soak up the electrolytes and saturate as fast. If all else falls, shock
treatment is still an option. The shock hurts but patients are usually
sedated and given a mild anaesthetic.
Extra beats
As people get older, the millions of sponge-like cells in the heart get
aggravated or wear out. Sometimes they get overexcitable and fire on their
own without waiting for the master pacemaker to cue them. This can happen in
any of the chambers and it results in extra beats called extrasystoles. For
many years doctors were very fearful of these extra beats because it was
felt that they inevitably caused all the other cells to go crazy, leading to
dangerous fibrillation. After all, it is well known that people don't die
from clogging of the arteries (heart attacks); they expire from sudden death
cardiac arrhythmias.
Over the past few years doctors have learned that extra beats are more
common than they thought. Huge numbers of "normal" asymptomatic volunteers
had cardiac monitoring for 24 hours at a time. Scientists found that 60
percent of what they considered the normal ("thin") population have a few
extra beats every day. Most people don't even realize these beats occur.
They often feel like a tickle in the throat or chest. Unfortunately, some
people are painfully aware of these skips and feel the heart
"flip-flopping. "
As long as there is no underlying clogging of the arteries or any other
serious damage from illness or infection, these beats are usually innocuous.
Or so it was thought.
What about us?
Over the past few years I have heard from many large people who experience
extra beats, and whose doctors have told them they have nothing to worry
about. The problem is that no one has ever surveyed or done proper research
on obese subjects. This is worrisome because any advice is anecdotal and
pure guesswork. I surveyed some so-called experts who have given me
conflicting advice. Some say the hearts of large people have been damaged by
fat infiltrating the electrical system (fat cardiomyopathy) causing serious
extra beats. Others usually point to sleep apnea as a cause. In a previous
article I described apnea as a condition whereby the large thick structures
in the neck and throat cause bouts of gasping and snoring during sleep. The
resultant lack of oxygen definitely causes extra beats or bouts of very
rapid beating in an effort for the body to at least get what little payload
is in the system quickiy to where it is needed.
The problem with this seemingly simple explanation of why large people get
irregular of fast rhythms, is that even when the apnea is corrected (or when
people have lost lots of weight and no longer require sleep apnea machines)
the extra beats seem to persist during the day. In this scenario sleep apnea
is not the problem. I am not satisfied with all of these explanations.
I am especially perturbed at the usual answer; "tell fat people to lose
weight and they will be better off." I know of many large people who lost
huge amounts of weight and their irregular heart beats often got worse. It
is well known that rapid dieting is deadly and many succumb to sudden death
from heart arrhythmias.
What I read on the internet talked about potassium and water for a-fib but you can't drink a lot of water without replenishing with salt AND potassium - we're not talking a lot of sea salt in a glass of water, maybe 1/4 teaspoon. Potassium (and magnesium) and salt and water all are important for bodily functions. 
