Heart rhythm problems (arrhythmia)

The heart runs on wiring of its own: it sets the rate and keeps the upper and lower chambers contracting in turn. When that wiring slips, the heart beats too fast, too slowly or unevenly, and that is what arrhythmia means. Most of these slips are harmless. The danger of the few that are not has nothing to do with how dramatic they feel: the most alarming palpitations can be entirely benign, while a rhythm that threatens life may barely register.

What it feels like from the inside

• the heart pounds, flutters or seems to drop away, for a few seconds or for several hours;
• skipped beats: one goes missing, then a hard thump follows in the chest;
• breathlessness on exertion and sometimes at rest, with tiredness arriving early;
• dizziness, vision going dark, the feeling that a faint is on its way;
• pressure or discomfort in the chest.

In older people all of this often boils down to weakness and shortness of breath, with no sense of a beating heart at all. And some arrhythmias are not felt in the slightest: atrial fibrillation is frequently found by chance on a routine ECG, or only after a stroke. That is why, past sixty, it is worth checking the pulse at the wrist now and then even when you feel perfectly well.

Where normal ends

At rest an adult heart does between 60 and 100 beats a minute. In trained people and during sleep a pulse of 45 to 55 is normal, not an illness. In children and young adults the rhythm speeds up noticeably on breathing in and slows on breathing out: this is respiratory arrhythmia, another version of normal.

Odd extra beats occur in almost everyone. With a healthy heart they are not dangerous, though they feel unpleasant and grow more noticeable in silence, before sleep, and after coffee or a night without rest. A faster pulse with exercise, with nerves or with a fever is normal too.

It is worth looking into if an episode starts and stops abruptly; if the pulse is constantly irregular, or stays above 100 or below 40 at rest; if palpitations come together with fainting, breathlessness at rest or chest pain.

How the types differ from one another

• Atrial fibrillation. The commonest, and commoner with every decade. The pulse is entirely irregular, beats of different strength arriving at uneven intervals. The main threat is not the palpitation but clots that form in a poorly contracting upper chamber and travel to the vessels of the brain.
• Supraventricular tachycardia. An attack of a regular, very fast beat that switches on and off sharply. It occurs in young, healthy people, rarely threatens life and responds well to treatment.
• Extra beats. The familiar skips and dropped-out sensations. What matters is not that they exist but how many there are and what the rest of the heart is like.
• A slow pulse and blocks. Weakness, sluggishness, blackouts. Sometimes rate-slowing medicines are to blame, and reviewing them with a doctor is enough.
• Ventricular arrhythmias. The most dangerous of all: collapse with no warning, or cardiac arrest. Mostly in people who have had a heart attack, who have damage to the heart muscle or who carry an inherited syndrome.

When to call without waiting

Call the emergency number (112 in Europe) if even one of these appears:

• chest pain or heaviness alongside a fast or irregular heartbeat;
• fainting with no warning, especially during exercise or in water;
• palpitations with breathlessness at rest, cold sweat or sudden pallor;
• an attack of fast heartbeat lasting more than half an hour and not settling;
• an irregular pulse together with a drooping face, weakness in an arm or a leg or slurred speech: that is a stroke, and minutes count.

If someone has collapsed and is not breathing normally, call for help, start chest compressions and send for a defibrillator.

Inherited causes and sudden death in the young

Some arrhythmias run in families and stem from inborn features of the heart muscle or of its electrical channels. Carriers look healthy and complain of nothing until the first event. This is the group behind the sudden deaths of young athletes.

These should raise a flag:

• fainting during physical effort, while swimming, or at a sharp noise such as an alarm clock;
• fainting in the middle of a strong emotion, a fright or a row;
• the sudden death of a relative under 40 or 50, including an unexplained drowning or a crash with no obvious cause;
• family cases of epilepsy that was never explained, or a pacemaker fitted early in life.

It is better to raise this with your doctor yourself: the question is not always asked, and it changes the whole course of the work-up. An ECG and an echocardiogram will be needed, often ECGs of close relatives as well. Once the diagnosis is confirmed, some everyday medicines are off limits: certain antibiotics, antifungals, anti-sickness drugs and antidepressants act on the electrics of the heart, and every doctor you see will have to be warned about it.

What sets the rhythm off

Quite often the heart itself is not the culprit:

• an excess of thyroid hormone, anaemia, a high fever, dehydration;
• low potassium and magnesium, with diuretics, vomiting or diarrhoea for instance;
• pauses in breathing during sleep in people who snore, a common and frequently missed companion of atrial fibrillation;
• alcohol, a single heavy evening included, nicotine, caffeine and energy drinks, stimulant substances;
• medicines: decongestants that narrow the blood vessels, too high a dose of thyroid hormone, individual drugs from the classes named above;
• high blood pressure, coronary disease, valve defects, past inflammation of the heart muscle.

Many of these causes can be removed, and the rhythm then rights itself without any treatment aimed at the arrhythmia.

Catching the episode on a recording

An ordinary ECG shows only the seconds you spend lying under the machine. When attacks are rare it comes back normal almost every time, and that does not mean all is well. So other tools are used:

• monitoring over a day or a week, and stick-on monitors worn for a fortnight;
• a recorder the person switches on themselves the moment an attack starts;
• a recorder placed under the skin for months, for rare unexplained blackouts;
• an echocardiogram, to see whether muscle and valves are healthy;
• an exercise test, if the attacks are tied to movement;
• blood tests: haemoglobin, potassium, magnesium, thyroid measures.

Smart watches notice an irregular rhythm and record a simple ECG: keep the trace and show it to your doctor, but the diagnosis comes from reading the tracing, not from a symbol on a screen. The most valuable thing here is something you can do yourself: during an attack, count the pulse and note when it began and when it ended, and whether it ran even or ragged. That tells a doctor far more than “I felt awful”.

What treatment achieves

Many people need no treatment at all: observation and removing the trigger are enough. Otherwise the choice depends on the type of arrhythmia and on its cause.

• Medicines. They slow the rate or hold the correct rhythm: most often beta blockers and antiarrhythmic drugs. A doctor selects them, and stopping abruptly, beta blockers above all, must be avoided.
• Stroke protection. In atrial fibrillation the question of anticoagulants is settled separately, on the overall balance of risk rather than on how you feel. Aspirin does not do this job.
• Ablation. Pinpoint burning or freezing of the spot that launches the arrhythmia; in supraventricular tachycardia it often removes it for good.
• Cardioversion. Restoring the rhythm with a shock under brief anaesthesia.
• Devices. A pacemaker for a persistently slow pulse and for blocks, an implanted defibrillator where the risk of dangerous arrhythmias is high.

The manoeuvres that break an attack of supraventricular tachycardia, such as bearing down or splashing the face with cold water, do work, but they may be used only after a doctor has shown you how, and never during chest pain or a near-faint.

Online consultation about palpitations

In an online consultation the doctor will go through what your attacks look like, take the family history, look at ECGs already done and at traces from a watch, explain which investigation stands a chance of catching the arrhythmia in your case, and tell you what to do during the next episode.

Such a conversation is no substitute for emergency care: with a faint, chest pain or signs of stroke you call the emergency services rather than book an appointment.

This material is for information only and does not replace medical advice.