An abnormal heart rhythm can be either due to a rhythm that's too fast which is called
a tachycardia or too slow which is called a bradycardia. Now we're going to focus here
on the tachycardias which are the fast heart rhythms and typically you feel palpitations
or a sense of a rising sensation in your heartbeat or any regular type of heartbeat. The most
common heart rhythm abnormality is called atrial fibrillation and this is where there
is a chaotic random series of activations in your heart that makes your heart feel like
it's flip-flopping in its rhythm in the chest. The other types of heart rhythm abnormalities
we would encounter in order of how common they occur would be atrial flutter, an SVT
or a supraventricular tachycardia, and this is the medical terminology to describe when
you have a fast heart rhythm due to the top chambers of the heart beating very quickly.
And the forms of SVT that we talk about are typically a Wolff-Parkinson-White syndrome
where you have an accessory pathway or connection between the top and the bottom chambers, or
a second form of SVT which is called AV-nodal reentrant tachycardia; which is also known
as AVNRT. So, in summary, the heart rhythm abnormalities that we might encounter are
firstly atrial fibrillation which is the most common, atrial flutter, an SVT which can comprise
of Wolff-Parkinson-White syndrome or WPW or an AV-nodal reentrant tachycardia or AVNRT
syndrome. And those are the essential heart rhythm abnormalities in terms of the tachycardia
that you might encounter.
Now, we understand atrial flutter causes palpitations but what triggers atrial flutter are typically
a patient who has a history of hypertension or valve disease, and one of the emerging
risk factors that we see with atrial flutter is sleep apnea. Now, sleep apnea in itself
is a disorder of sleep where if you're lying in bed at night, and particularly if you're
slightly large and a snorer, you obstruct potentially your airway several times in the
night and this causes an acute rise in adrenaline. Every time you have to wake up from the obstruction
of the airway, you trigger changes in the lungs which then feed back into the heart
that causes the stress in the heart. Now, as the heart is affected by sleep apnea and
the stresses and strains of sleep apnea, what can emerge is the propensity of the heart
to develop conditions such as atrial fibrillation and atrial flutter. So, one of the emerging
things that we're seeing with the epidemic of atrial fibrillation that we're seeing as
well as atrial flutter is that more and more patients should really be screened for sleep
apnea and effective treatment for their obesity, for their sleep disorder can be a very
important management strategy in helping to improve the outcomes from atrial fibrillation
and atrial flutter.
The major symptoms from a heart rhythm abnormality would be palpitations. Now, what are palpitations?
These are a sensation that you might have that your heart is not beating in rhythm.
So, any regular heartbeat or a very rapid heartbeat which can be either sustained or
it can be intermittent. This would be one of the major symptoms of the heart rhythm
abnormality. If your heart rhythm abnormality is sustained or your heart is beating very
quickly due to an arrhythmia, then what you might also start to experience are symptoms
of chest discomfort, lightheadedness, shortness of breath in addition to the palpitations
that you might experience.
In order to make a diagnosis of a heart rhythm abnormality, doctors typically need to see
a symptom to ECG correlation. Now, what is an ECG? An EEG is an electrocardiogram. It's
an electrical recording of your heart typically made from electrodes that are placed in your
chest wall and also your arms and your legs, and this typical pink sheet of thermal paper
that comes out with the squiggly lines records your 12-lead electrocardiogram or ECG. And
the best way that we can make a diagnosis and the most accurate way to make a diagnosis
is in order for you to have an arrhythmia captured simultaneously at the time that you're
having an ECG recorded. Now, this is often easier said than done because how often is
it that you walk into your cardiac diagnostics laboratory and happen to have a heart rhythm
abnormality when you're recording your ECG, and this poses a problem for most people to
be able to capture this heart rhythm abnormality. So, what are the solutions that are available
to try and capture something that happens intermittently? And for this we have other
diagnostic tests. One of the most common ones we use in cardiology is called a 24-hour Holter
recording, and this is where you're connected to typically 3 ECG electrodes and you go home
with it for either 24-48 hours or sometimes 7 days, and if you continue your normal activity
and you happen to record or experience one of these heart rhythm abnormalities, then
the continuous recording that the Holter performs will be able to accurately give you a diagnosis.
Now what happens if your heart rhythm abnormality occurs, say once every six months? This is
one of the great frustrations in the past for patients and physicians to be able to
capture a diagnosis, and what we have now is actually something that is empowered by
mobile technology. And this is what it looks like. I have with me what we call a mobile
two lead ECG recording device, and this particular device is called the AliveCor Kardia Mobile
device. K-A-R-D-I-A. And it's very effective because you can buy this yourself at home
and you can couple it to a phone and here I happen to have an iPhone, but this works
on any modern phone, and if I now hold this electrode in my fingers-- and I'm going to
show you a screen very shortly-- you can see the beginnings of the recording of an ECG,
and this is my ECG live being recorded at a time of my choosing because I can always
have this gadget in my pocket and coupled to my phone, and when I record such an trace
which captures some of my heart rhythm abnormalities, I can bring my phone with the data available
on the phone to show my physician, and if your physician is somebody like an electrophysiologist
who can read this single lead ECG, the diagnosis is often very clear. Technology companies
are now catching up with AliveCor, and for example, the Apple iWatch series 4 or 5 has
this ECG technology. It's a very expensive ECG and may serve other functions such as
telling the time, but it will be able to get you an ECG of sufficient medical grade for
your doctor to make a diagnosis of a very rare heart rhythm abnormality. And so I'm
getting more and more patients who come into clinic with their own ECGs and I'm comfortable
making a diagnosis on the basis of this mobile technology-enabled direct recordings of ECGs
that are crucially importantly done simultaneous with your actual symptoms or palpitations,
and that is how we're making more and more diagnoses, for example, of atrial fibrillation
which is incredibly important to make.