Managing your Own AF
In atrial fibrillation the atria are contracting at 600 cycles per minute. The ventricular rate (otherwise known as the pulse rate) is obviously a great deal lower, and the ratio of cycles of AF to ventricular rate is largely determined by the degree of blockade within the atrioventricular node (so called AV node). In many patients during atrial fibrillation the AV node is unable to block sufficiently well, and therefore the ventricular rate, or pulse rate, is speeding faster than normal, typically in the range of 100 – 180 beats per minute.
In a few patients, the degree of efficiency of the AV node is so high that the heart rate, even in AF, is actually in the normal range, and these patients would often not even know that they are in atrial fibrillation as a result.
In most patients with atrial fibrillation, medication is taken to increase the efficiency of the AV node. The most commonly used medication would be beta blockers, such as Nebivolol, Bisoprolol, Metoprolol, and Propranolol. Taken each day, this drug activates the AV node, making it more efficient and thereby lowering the ventricular rate/pulse rate. Other drugs that are used for this include Verapamil, Diltiazem and Digoxin.
During intercurrent illnesses, the degree of AV nodal blockade is altered as a result of the stress hormones. As a result, standard medication may not be as effective in lowering the heart rate. A very common problem therefore in patients with longstanding atrial fibrillation is that the heart races (ie:- the pulse rate increases) outside the normal range, and can be as high as 180 beats per minute. The racing pulse produces additional negative effects on the circulation and can cause flooding of fluid into the lungs, complicating the illness.
As a result of these phenomena, I advise patients who have longstanding atrial fibrillation to monitor their pulse rate, and ideally their ECG, during any illness. Should the pulse rate accelerate during the illness, either as a result of the illness or as a result of medication (such as Ventolin inhalers which accelerates the pulse rate), then some steps may be necessary to control the problem.
In the first instance, this may be a slightly higher dose of beta blocker, eg:- 5 mg Bisoprolol is increased to 7.5 mg, or even 10 mg, once a day, or alternatively other drugs such as Digoxin can be given along with their general medication. The use of such medication can be discussed on a patient by patient basis in outpatients, or can be discussed at the time of the episode once the heart rate has been accurately recorded and returned to us.
In summary – during intercurrent illnesses, whether this a chest infection, urine infection or viral illness, the medication that is normally taken to control the heart rate in patients with AF may be insufficient to be effective, and additional measures may be needed by monitoring their own ECG using, eg:- Homecare ECG, available at Surrey Cardiovascular Clinic. Patients can be fully engaged in this process, and in many cases can avoid hospitalisation as a result of taking action using simple medications prescribed by their GP, or from us at Surrey Cardiovascular Clinic.