Cardiac arrhythmia is a change in the heart’s rhythm.
Normally the heartbeat is conducted with an impulse that starts
in the top chambers of the heart and then in a very coordinated
fashion, the impulse is then conducted down to the bottom chambers, the main pumping chambers,
the ventricles. Anything that upsets that pattern of the heart’s pacemaker working
and firing and sending impulses down to the bottom chambers results in a change in cardiac arrhythmia.
A change in slow heartbeat results generally
from the heart’s own pacemaker not functioning properly or the impulse is blocked in the
chamber that conducts the impulse through from the top to the bottom chambers.
On the other hand, the heart can suddenly beat too fast and that’s because usually, areas outside
the normal electrical pathways take over and beat very rapidly because of a short circuit
in either the top chambers or the bottom chambers.
It can be diagnosed in several ways. Usually
the patient complains of symptoms. They may feel their heart suddenly beating too fast
or too slowly. They may complain of feeling dizzy because their heart rate is too slow
and their blood pressure drops as a consequence. They may feel faint. They may actually faint
and lose consciousness. Aside from what the patient tells us, there
are a number of simple tests that we can do to make the diagnosis. Probably, the commonest
is to do an ECG, that’s to record the electrical activity of the heart just by putting a series
of electrodes on the outside of the chest wall and recording that and we can see from
the ECG whether the heart is in the normal rhythm or an abnormal rhythm very readily.
If we still can’t obtain a diagnosis, then we can introduce tiny, little electrodes through
the vein at the top of the leg and pass those around to the heart and record the electrical
signals directly from within the heart and workout from that procedure whether the individual
has an extra electrical connection or an irritable focus inside the heart that can make the heart
suddenly speed up. Equally, we can also assess how the heart’s own pacemaker functions
in whether it’s not functioning properly.
The treatment of heart arrhythmias depends
largely on the underlying diagnosis. If it’s clear from the investigations that the heart
is beating too slowly, then the best and indeed the only treatment is to implant a pacemaker.
If the heart is beating too quickly, then there’s the two main treatments are ones
which involve medication to try and slow the heartbeat. If the medicines are not successful
in treating the faster heart rhythms, then a very good and alternative treatment is one
called catheter ablation which involves inserting electrodes through the vein
at the top of
the leg and cauterizing or freezing the abnormal pathway or irritable focus inside the heart
in order to stop it being active, and that for certain rhythms is the treatment of choice
because it provides a very high success rate of treatment in the order of 95 to 99% success
rate for a single procedure.
There are some dangerous heart rhythms and
ones that we want to be absolutely sure that we’re treating correctively because the
patient is at risk of dying without the appropriate treatment. These are mainly seen in patients
who’ve had damaged hearts. They may have had previous heart attacks which have affected
the heart muscle and so the heart muscle is not functioning properly. These patients are
at risk of ventricular arrhythmias. These are rhythms coming from the main pumping chambers
and at their worst, they can lead to a cardiac arrest.
One important development in the treatments of arrhythmias has been the design of implantable
devices called ICDs which offer life saving therapy because they’re able to shock the
heart back to a normal rhythm thus saving the patient’s life. These devices have been
shown to be lifesaving under these circumstances. Thankfully, most rhythms are not life threatening,
but for the few that are, then implantation of these devices is really lifesaving.