Palpitations are a very common presenting complaint to front-line medical services (primary care and emergency departments (EDs)).
They are often a problematic symptom for several reasons:
Palpitations often cause great anxiety and distress for the patient, which can put a lot of pressure on the consulted medic.
Most palpitations are benign, but a small minority can represent a life-threatening condition. Efforts to identify the latter can sometimes overshadow investigations and referrals.
The patient is commonly asymptomatic when they present to their GP, so evaluation for pathology must be undertaken in the absence of signs.
Investigations are often normal and can give false reassurance.
In this article, I will offer five tips on how to approach these patients — how to get the most out of the history, the electrocardiography (ECG) and other investigations and, perhaps most importantly, how to risk stratify your patients.
<strong>Tip 1: What to ask in the history</strong>
Inevitably, the patient with palpitations will be asymptomatic when they consult their GP/front-line medic. Therefore, the history is crucial in formulating a differential diagnosis.
First, find out what the patient means by ‘palpitations’ (if they use that word) — make sure they don’t actually mean chest pain.
Get a clear but detailed description of the patient’s palpitations.
Ventricular ectopic beats are often described as ‘missed beats’, ‘skipped beats’ or ‘jumps’.
Supraventricular tachycardias usually have a sudden onset, with an elevated heart rate and an abrupt offset. Atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular re-entrant tachycardia (AVRT), atrial tachycardia and atrial flutters usually have a regular pulse whereas atrial fibrillation (AF) is irregular.
Ventricular tachycardia usually starts abruptly (sometimes the patient may describe some ‘missed beats’ beforehand), gives an elevated heart rate and often is poorly tolerated by the patient.
It is essential to ascertain (by direct questioning if necessary) whether there are any other symptoms associated with the palpitations.
This is very important in order to risk-stratify the patient.
Symptoms such as chest pain, syncope and pre-syncope are red flags and should prompt the medic to look for structural heart disease and to make an urgent onward referral.
<strong>Tip 2: The value of clinical examination and basic investigations</strong>
The purpose of the clinical examination in a patient who presents with palpitations is to assess for structural heart disease. A patient with palpitations in the presence of structural heart disease is automatically high-risk and almost always requires an onward referral to a cardiologist (see Tip 5).
When examining the patient, look out for murmurs (aortic stenosis), overload or respiratory crepitations suggesting left ventricular dysfunction and, of course, arterial hypertension (a cause of ventricular ectopy).
The value of basic, cheap and available investigations in formulating a differential diagnosis is perhaps under-appreciated.
A lot can be taken from a basic blood panel, for example. Is the patient anaemic, causing a high output state and sinus tachycardia?
Does the patient have sinus tachycardia or even AF from thyrotoxicosis? What is the potassium? Is this actually renal failure?
<strong>Tip 3: Interpretation of the resting ECG</strong>
Even in the absence of ‘active palpitations’, the resting ECG can be very useful in the hunt for pathology.
Again, you are looking for features that suggest underlying structural heart disease.
On the resting ECG, look out for:
Left bundle branch block.
ST or T wave segment change suggestive of ischaemia.
Q waves of an old myocardial infarction (MI).
Left ventricular hypertrophy (LVH) by voltage with strain pattern.
Delta wave of Wolff-Parkinson-White (WPW) syndrome.
Heart block (first-, second- or third-degree).
Abnormal QT interval.
On this page, I have collated some ECGs of ‘lesser-spotted’ conditions associated with palpitations.
Figure 1 shows complete heart block.
On this ECG, we can see the following salient features of complete or third-degree heart block:
1. More P waves ($) than QRS (*).
2. Regular P waves (not associated with a QRS complex).
3. Regular QRS complexes (usually at a slower rate than the P waves).
4. Dissociation between the atria and ventricles.
In this example, the QRS complexes are wide (>120ms), indicating that the escape rhythm is coming from low in the conduction system. This is a high-risk situation.
Figure 2 shows ventricular pre-excitation, which when occurs in association with palpitations, gives the WPW syndrome.
The features of WPW evident on this ECG are:
1. Short PR interval (__).
This is caused by accelerated conduction between the atria and the ventricle as the action potential can bypass the AV node and get to the ventricle early via the accessory pathway.
2. Delta wave ($).
A delta wave is the slurred upstroke of the QRS seen across the precordium and in the limb leads here.
It is formed by the fusion of myocardial activation via the AV node (gives a normal, rapid upstroke to the QRS) and myocardial activation via the accessory, or bypass tract (giving a very broad and abnormal QRS).
Figure 3 shows the long QT syndrome.
Here, the QT interval is extremely long (measures 640ms).
Normal intervals are <430ms for men and for <450ms women.
The correct way to measure the QT interval is using the Tangent Method, where one measures from the start of the QRS to the end of the T wave, as determined by a tangent line from the end of the T wave to the isoelectric baseline.
<strong>Tip 4: Getting the most out of ambulatory monitoring</strong>
The aim of any period of ambulatory monitoring is to get a symptom-rhythm correlation, that is, to record the heart’s rhythm when the patient is having their symptoms of palpitations. This should give the rhythm diagnosis of the patient’s complaint, or indeed, demonstrate a normal sinus rhythm and rate, prompting a search for a non-cardiac cause.
In order to maximise the chance of obtaining a symptom-rhythm correlate, the duration of the monitoring period must match the symptom frequency.
Daily symptoms should be captured on a 24-hour Holter monitor, whereas if the patient reports infrequent monthly symptoms, an alternative form of monitoring should be sought.
In most cardiac departments, a variety of monitors are available. These usually include 24-hour, 48-hour, 72-hour, and seven-day monitors and patient-activated monitors, which can stay on for several weeks.
The newest generation of implantable loop recorders are extremely low-profile, with a battery life of up to three years (for example, the Reveal LINQ device by Medtronic, see Figure 4).
These devices are designed to be inserted in a procedure room within a few minutes and do not require any sutures.
They are most useful in patients with very infrequent symptoms. All have home monitoring capability and both automatic and patient-activated recording.
A very useful recent development in the field of ambulatory monitoring has been that of hand-held smartphone monitors. The AliveCor by Kardia attaches to the back of a smartphone. The two metal thumb pads (see Figure 5) record and display a single-lead ECG. Recordings and events can then be saved for review later by a physician.
<strong>Tip 5: How to risk-stratify</strong>
Perhaps the most important aspect in the approach to the patient with palpitations is risk stratification. Here, you identify the patient who is in danger or who needs urgent onward referral from the majority of patients who can be reassured.
Figure 6 shows a ‘traffic light’ approach to the risk stratification.
Red-flag symptoms signalling urgent referral include syncope or pre-syncope in association with palpitations and symptoms during exercise.
The patient with known or suspected high-risk structural heart disease (severe aortic stenosis, previous MI, congenital abnormality) who presents with palpitations should always be referred onwards in an urgent manner, as they are at risk of ventricular tachycardia.
The same goes for patients who have a family history of inherited cardiac disease (hypertrophic or dilated cardiomyopathy, Long QT syndrome, etc) or of sudden cardiac death.
A 12-lead ECG showing a broad, complex tachycardia mandates emergency transfer to hospital, as does complete (third-degree) heart block.
Second-degree heart block on ECG should also be urgently referred to the ED, as the risk of progression to complete heart block in high here.
Green — low risk.
<em>Referral not usually required</em>
Amber — medium risk.
<em>Should be referred</em>
Red — high risk.
<em>Urgent/same-day referral to hospital</em>
<strong>References available on request</strong>
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