This is a transcript of a talk given by Dr Andria Coley, CardioThorasic surgeon from the University of Texas, Cardiology Institute. It deals with the present knowledge of Atrial Fibrillation as of 2022.
Here is the URL if you prefer to watch the Video.
The transcript can serve as a useful check list.
1/
For decades the medical profession have had the impression that A-Fib
is really not that serious. You have an episode, get over it and carry
on.
2/ From studies, following up on people with A-Fib it became clear that A-Fib is a serious problem
and it is becoming more and more common. Recently a great deal of
research has been carried out on A-fib, on its prognosis and how to
treat it.
3/ People with A-Fib have a 5 times greater chance
of a stroke, three times greater chance of heart failure and twice the
chance of early cardiac caused death.
4/ A 5 year study of a
group of patients who had A-fib for the first time, which was serious
enough for them to be hospitalized, showed a huge increase in a whole
range of conditions over the following years. These included a high
rate of heart failure, high rates of stroke, heart attacks, bleeding
problems from being on blood thinners, and most serious, just under half
of these patients passed away within the 5 year study period.
5/
A-Fib is 2 to 3 times as prevalent in the USAas in other 'western'
countries. She puts this down to the American diet, way of life and
other medical problems that are common in America.
6/ There are a number of new options for sorting out A-Fib.
7/
In the healthy heart, the Sinus Node at the top of the Left Atrium starts the pulse. The
pulse is picked up by the AV node which sends it to the Ventricles.
Note: the blood enters the Atriums which pumps it to the ventricals which pumps it to the body (0ne side of the heart) or to the lungs (the other side).
8/
When a group of rogue cells 'decides' to send a false signal, it causes the
Atrium to fibrillate - a little like the twitch you get in your eye
sometimes.
9/ If this rogue signal hits the AV node it causes
Rapid Ventricular Response. ie. The heart speeds up. This is when
people typically feel A-Fib. When the Atrium is in A-fib, it can happen
without the person being aware. What we feel consciously is the
ventricle pulsing away at a rapid rate. The complications (see below)
from A-Fib occur even when only the Atrium is involved (even without the rapid Ventricular pulsing).
The Pathopysiology of A-fib
1/ AF is refractory (hard to treat).
2/
AF can cause heart scarring. Electrical signals are transmited through
muscle, not through scar tissue. Scar tissue can disrupt normal signal
transmission but can also be used by a surgeon to stop abnormal signal transmission.
3/
AF can cause the heart to stretch, further disrupting normal signalling
leading to more A-Fib, leading to more stretching (and scarring). A
really bad cycle.
4/ Early A-Fib is called paroxysmal (comes
and goes), usually from one wee cluster of cells that has gone rogue.
Usually this is on the back of the left Atrium where the veins from the
lungs enter the Atrium.
5/ About 6 months after this first
stage, if it hasn't been taken care of, things change. Scarring and
stretching begins to occur, messing up the signaling and starting what
the Electro-Physiologists call a rotor. This causes non-paroxysmal, or
prolonged AF. At this stage the new treatments that are coming on line,
are useful. The old methods can't cure A-Fib at this stage in the
progress of the disease.
6/ AF is responsible for a fifth of the strokes in the USA.
7/
The Atrial Appendix is one spot particularly indicated in forming clots
since the blood tends to pool there, especially in someone who has AF
and hence does not have a completely one-way flow of blood.
Note: The Atrial Appendix is a wee pocket in the wall of the heart of no known use. A surgeon can put a plug in it if he is inside the heart or a clamp, if outside the heart. This gets rid of the main source of blood clots. If a clamp is used, the wee pocket dies and ceases to be a problem.
8/ Of particular concern, as the
heart stretches, it pulls the sides of the vales apart and the valve can
no longer close completely. This allows back flow of
blood and increases the chance of a clot forming and hence stroke.
9/ This whole process of stretching and scarring leading to more AF is a vicious downward cycle.
What can be done (in increasing order of intervention)
1/
As has been done for some time, anticoagulants are taken to avoid
stroke. Much better choices than Aspirin are available these days.
Aspirin only affects the platelets and stops them clotting. The
medicine must be taken continually since one can not tell when one is in
A-Fib if it doesn't trigger off the AV node, (causing the Ventricle to
speed up). Clots can form within 5 minutes of A-fib starting.
2/
Some people can not tolerate being on thinners. For these folks a
surgeon will often either block off or pinch off the Atrial Appendage/appendix
since this is where 95% of the clots are created. The AA isn't needed
for proper heart function.
3/ Beta blockers are meant to stop the Ventricle from racing but they don't stop A-Fib or the complications that come with it.
4/
Other medications such as Amiodarone HCl are sometimes tried to
re-establish normal cardiac rhythm but If AF continues, they can make
one feel pretty bad. These medicines can also affect the liver.
5/
Resetting the heart with a shock. If you already have an advanced AF,
the reset from a shock, likely won't last. Shock is more effective in the very early
stages of AF.
6/ Ablation(1), using scar tissue to stop bad
signals. Done by an Electro-Physiologist with a probe inserted through a vein in the groin. This is for the paroxysmal (early) AF in which the rogue
signal is being generated where the veins enter the Atrium from the lungs. If AF is
caught early, it is highly effective. When done for a later, more advanced case, success is only about 35%.
7/
Ablation (2) (when the surgeon is in your chest), She scars a maize
over your heart which only allows the good signals to propagate. Even
for the really difficult cases, this technique is effective in 85 - 90%
of cases.
8/ The best system - the Hybrid maze.
Cardio-surgeon
goes in through a small incision just below the breast bone, and with a probe goes up to the heart and scars
the appropriate part of the outside of the heart. A few days later the
electropysiologist goes in through a vein in the groin and finishes the
job from inside. Success is around 80%.
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