Many patients try to find reasons why their AF has started and look for things they do that may have initiated it. The truth however is that it is rarely the fault of the patient – so do not blame yourself. AF is strongly associated with underlying cardiovascular problems such as high blood pressure, heart failure, coronary heart disease and valvular heart disease.
Non heart problems that can cause AF are excessive alcohol (particularly binge drinking) or an overactive thyroid gland disease. Finally in about 30% of people a cause is never found and as far as we can tell their heart is completely normal in all other respects, this is termed “lone AF”.
Trigger and substrate
No one is sure why AF happens but it is likely that there are two factors to consider, the AF trigger and the AF substrate.
Trigger
AF is started by a trigger. Although the sinus node is usual pacemaker of the heart, all the cells in the heart have the potential to spontaneously activate. The normal heart cells are dominated by the sinus node and they activate only after they receive the electrical signal from the sinus node (link to electrical system of the heart). It is quite normal for other heart cells to occasionally activate spontaneously at the wrong time causing an ectopic (meaning in the wrong place) or extra heart beat. This is experienced as a skipped heart beat which makes the heart feel irregular for a few seconds, as opposed to AF which makes the heart feel irregular for much longer.
Occasional ectopic beats are experienced very commonly in people with normal hearts. In people who experience AF however groups of rogue atrial cells are producing ectopic beats rapidly and very frequently. These frequent ectopic beats are the trigger for AF. The rogue cells are usually grouped at the junction between the left atrium and the veins that drain blood from the lungs to the heart (pulmonary veins). It is not fully understood why the pulmonary veins are the usual location for the AF triggers but it may be because the atrial cells are abnormal within the veins. An example is in patients with high blood pressure, where the high pressure in the heart stretches the pulmonary veins altering and distorting the atrial tissue there. This makes them prone to fire ectopic beats. In patients who have otherwise normal atria the ectopic beats will initiate the AF but it soon stops on its own because the atria is not able to continually fibrillate for a prolonged period. This is called paroxysmal AF.
Substrate
The substrate for AF describes an abnormality in the electrical properties of the atrial tissue itself. In order for the multiple chaotic fibrillation waves to continually circulate around the atria they need a certain amount of room to move around. In the absence of sufficient room in they will just collide into each other and stop. A large atrium in which the electrical waves move slowly provides the ideal conditions for these perpetual waves.
By travelling slowly they leave plenty of time for the cardiac tissue to recover and become excitable so this means that the waves are more likely to always be moving towards excitable tissue. This ‘substrate’ is caused by many types of heart disease and is detectable on tests such as an echocardiogram as enlarged atria. If a patient’s heart is sufficiently abnormal then the substrate may allow the AF to be sustained without any need for the triggers described above. This is called persistent AF.
AF begets AF
It is a common story for patients to start with occasional paroxysmal AF however the attacks then become more frequent and last longer and longer until eventually the AF becomes persistent. This is because AF itself changes the electrical properties of the atria and causes the atria to dilate, in other words creates the substrate for persistent AF. Hence a term often used by doctors ‘AF begets AF’. The importance of this is that if AF is treated early its progression can be halted...
This article was sent to me this morning and is quite a straight forward explanation in its simplicity....C
NO whoever told you that was mistaken. Lone AF means that is the only heart condition you have. Trust me we have been using this term since I started with AF-A seven years ago.
great explanation for what sometimes seems unexplainable.
Some years ago my husband was found to have a LB.B.B. on ECG.but
no signs or symptoms of anything else.
After a G.A. he went into AF. This took a long time to sort ,becoming PAF.
Can't remember the last episode he's so well controlled.
Fast forward to now. Few days ago needed surgery. We begged for an epidural anaesthetic ......which he got, but they had to give other drugs.
Now there are lots of ectopics. Now discharged by the surgeons he's back to the gp. The local heart docs not interested in him because his PAF history. .....or lack of.
The gp certain its a particular group of medications used in anaesthetics
The plain fact is that whilst these drugs may have triggered the AF they are seldom what caused it. To have AF you need a pre-disposition in the heart . A perfectly normal heart CAN be made to fibrillate by infusing a particular drug but stops the instant that the drug is ceased. I can't remember the name but it is sometimes used during ablation to stimulate the heart into AF to allow the EP to see where it is coming from and to check that the burn has been successful. To the bests of my knowledge it is not used in any other cases. In patients who are vulnerable to AF. operations have been know to be triggers in the past so basically your GP is probably right.
I believe the name of the drug was Adenosine....It was administered to me intravenously to exclude the presence of latent Pulmonary Vein conduction prior to termination of Ablation....Carol...
Thank you. I'm good with facts but terrible with names. Succinctly put as always Carol. I remember proof reading a study about it earlier in the year. It has always been used by EPs but they needed to prove that a normal heart also reacted to it in the same way. Fibrillation stops the moment the infusion ceases where no rogue conduction is present as in successful ablation or one without AF to start with.
Agreed re pre disposition to AF which would be the lbbb.
However medics appear to have no real concern for problems they cause by prescribing medications which can be or are a cause of AF
a starting up. The surgeon prescribed one oral medication which has in its write up AF as a side effect. We had fingers crossed he would be OK. ........The general anaesthetic just tipped him over.
By the way .......my husband is not anticoagulated.
Hence our worries.
Thanks Carol, very interesting... Mine is lone AF as far as I know - one of my cousins has it too, so I suspect it runs (or rather walks quite slowly) in our family.
I have been diagnosed PAF, was told by a very good E.P, that sometimes the condition progresses, but also noted that the condition may not actually get any worse over time.
We discussed this when considering cyroablation, however in myself I believe the condition has become a bit more prevalent as Time has gone on, so have agreed for a SVT ablation as there is a chance I have re-entrant PAF.
Very interesting article though, thanks for posting u
Hi Bob, I understand that is the general understanding, and true in the majority of cases.
I had an in depth conversation with a well respected E.P about my options and choices, and I mentioned to him that I understood my condition would get worse, and for that reason I wanted an ablation. He then said that it does not always end up that way. each person is different, and in my case, the problems started as a non cardiac problem and developed into a heart rhythm issue. I have had most tests and no structural problem with my heart, it goes into a fib 3/4 times a year and has done since 18,now 31.Its adrenergic af, and know my triggers.
I agree with your comments in that af begets af (in most cases), but it is possible that in some cases avoiding the triggers, thus avoiding af can prevent the heart from re wiring itself.
I count myself fortunate that I am able to avoid triggers at present, but admittedly I have adjusted my lifestyle hugely to ensure this, hence why I want cyroablation.
Regards
Rich
P.s, documented cases of vagal and adrenergic af are relatively rare, and think the docs are still learning about its nature and origin.
Also good on you for helping so many people on this website, the condition is just as much emotionally draining as physically
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