Atrial Fibrillation (AF) – Advice and Tips on Management
Atrial Fibrillation (AF) – Advice and Tips on Management
Atrial fibrillation is the most common heart rhythm abnormality and presents with symptoms such as palpitations, lightheadedness, a feeling of shortness of breath and may present with swelling of the ankles.
The normal heartbeat
The heart’s usual pacemaker cells (situation in the right atrium and termed the sino-atrial node) normally beats at interval of just under every second (60-100beats per minute) or approximately 100,000 times in a 24 hour period.
These cells fire off electrical impulse which originate in the right atrium this electrical impulse then conducts down to the AV node, which is akin to a relay station, before sending the impulses down into the ventricles which start contracting in response to sino-atrial node activity. In a normal person without heart rhythm abnormalities, this process is repeated regularly and can happen approximately 100,000 times in a 24-hour period.
What happens in atrial fibrillation?
However in atrial fibrillation, other cells situated in the pulmonary veins, may fire rapidly and irregularly, triggering atrial fibrillation. These cells fire much more rapidly that the sink-atrial pacemaker cells, typically 300-600 beats per minute. These ectopic beats arising from the pulmonary vein leads to irregular conduction in the atria. The AV node is unable to transmit every one of the rapid beats, and therefore sends signals into the ventricles in an irregularly irregular manner, which we can feel as an erratic pulse , which characterises atrial fibrillation.Atrial fibrillation can be intermittent and this is termed paroxysmal atrial fibrillation (AF), or continuous which is called persistent atrial fibrillation.
TREATMENT STRATEGIES ATRIAL FIBRILLATION
The most important treatment strategy to consider if you are diagnosed with atrial fibrillation is stroke prevention.
Why do strokes occur more frequently in Atrial Fibrillation
The left atrial appendage is a structure that sits in front of the left atrium and in normal rhythm contracts to extrude blood in every cardiac contraction. In atrial fibrillation, the left atrial appendage may start to fill with blood which pools, due to inefficient contraction. The stasis (pooling) of blood results in formation of clots, and if these clots become dislodged and is then pumped into the aorta and makes its way into the brain vessels, it may cause blockade and eventually cut blood supply to the brain, causing an ischaemic (thrombotic) stroke. Strokes in AF are more severe and debilitating that strokes in the absence of AF.
Because of this, patients with atrial fibrillation should always be assessed for stroke risks one of the major treatment pathways.
What is rate control therapy for atrial fibrillation?
The next treatment option your doctor might want to discuss with you is drug therapy. Drug therapy is normally start at an atrial fibrillation to slow heart rates down in atrial fibrillation one of the major issues is not only the irregular heartbeat but how rapidly your heart beats which causes numerous symptoms including shortness of breath. The drugs that are started to control your rate normally take 2 or 3 days to act, and for you to start to feel a difference. The target here is to keep your heart rate typically under 100 beats per minute on average.
If you don’t feel sufficient difference or if the heart rate cannot be controlled with one agent the options are to start a second agent or indeed to increase the dose of the first one so that the heart rate control can be improved this is something that has to be monitored with your doctor. This process is called uptitration of drug therapy to get the desired appropriate heart rate control.
What is rhythm control therapy for atrial fibrillation?
The second form or therapy that your doctor might want to prescribe are drugs that control the rhythm of atrial fibrillation.
These are drugs which are given specifically to try and cardiovert you which means to restore normal rhythm. These drugs are drugs such as flecainide, sotalol or amiodarone and are given in a specific way to try and help restore normal rhythm.
One of the other treatment options that could be used as a cardioversion. This is where an electrical current which is passed through your chest wall in order to stop and restart the heart. A cardioversion might be suggested by a doctor if you have highly symptomatic atrial fibrillation or indeed if the drugs that have been given don’t appear to have improved your symptom profile.
One other treatment strategy that a cardiologist could help you with is a catheter ablation strategy this is normally conducted in a cardiology catheter laboratory. In atrial fibrillation ablation what a catheter is passed through the femoral vein in your groin and this catheter is then placed into the right atrium a small hole is created between the right and left atrium and a transeptal puncture is performed which creates a small hole to gain access to the left atrium.
The idea of an ablation procedure is to electrically isolate those pulmonary veins from which there can exist areas of ectopic activity rapid activity that conducts out into the body of the atrium so this can be done with either heating or freezing to destroy the areas around the pulmonary veins such that any activity that arises from within the veins can no longer conduct out to the rest of the body of the atria to cause atrial fibrillation.
What are success rates for catheter ablation for atrial fibrillation?
Success rates for catheter ablation range between 40 and 80%, depending on several factors.
For example, a patient who has intermittent (paroxysmal) atrial fibrillation with short lived episodes with no other risk factors or medical history of note, could expect close to a 70-80% success rate from one or more procedures.
However, another patient, for example with obesity, hypertension, longstanding persistent atrial fibrillation for 3 years, may be much more difficult to get back into normal rhythm, with only a 40-50% procedural success rates.
These factors which affect success should be assessed by your expert electrophysiologist, a specialist cardiologist who performs ablation procedures, and you should be informed of expected success rates when considering such a procedure
What are the complications of catheter ablation for atrial fibrillation?
Minor complications include groin haematoma, chest pain in the post-operative period which typically settles within 48hours, small fluid collection around the heart (pericardial effusion). These occur typically with rates < 4%
Major complications including life threatening complications are rare (<0.5%). These include a stroke, significant bleed around the heart, need for cardiac surgery, heart attack, and transient damage to the phrenic nerve affecting breathing for 6 months.
Dr Boon Lim is an atrial fibrillation expert who regularly trains junior doctors and colleagues on state of the art techniques to guide mapping and ablation of AF. To make an appointment, please contact 0208 187 9888