Disorders of the rhythm of the heart are common. The commonest anomalies are extra or premature heart beats, known as ectopics. These rarely cause problems on their own, neither do they commonly require specific treatment. Rarely, very frequent ectopic beats can be a sign of underlying structural heart disease.

Typically, cardiologists treat a variety of important arrhythmias with either drug therapy, or invasive treatments such as pacemaker implantation or electrophysiological studies leading to ablation therapy. Such important arrhythmias are classified as either tachycardias, where the heart rhythm is faster than it should be, or bradycardias, where the heart rate is inappropriately slow.

Supraventricular tachycardias arise from a site in the heart other than the natural pacemaker, but not from the main pumping chambers or ventricles. These Supraventricular Tachycardias (SVT) comprise two major sorts: regular, ‘short-circuit’ rhythms, which commonly occur in younger people and are the sort most people refer to as ‘SVT’; or atrial flutter and atrial fibrillation (AF).

AF and flutter tend to affect people later in life, and are not uncommonly associated with some underlying structural heart disease, or another trigger such as hormone disturbances, particularly an over active thyroid, or another acute illness or major physiological stress. The heart rhythm is often irregular or chaotic, and there is a risk of clots from the heart causing stroke, dealt with by recommending aspirin or in some cases warfarin to thin the blood. Treatment may include cardioversion (a medical electrical shock to re-synchronise the heart rhythm delivered under a short acting general anaesthetic), beta blockers, more powerful rhythm tablets such as amiodarone and dronedarone, or in selected cases, ablation therapy.

The other common SVT rhythms (technically, atrioventricular nodal re-entry tachycardia, AVNRT; and atrioventricular reciprocating tachycardia, AVRT) can start causing symptoms in younger people. These SVT rhythm problems can be treated effectively either by simple drug therapy, or, increasingly commonly, cured by a minimally invasive or keyhole treatment called ablation.

Ventricular tachycardias (VT) tend to be more serious, and can be potentially life threatening. VT can cause blackout, and if untreated, can progress to cardiac arrest.
Many cases of VT are associated with underlying heart disease such as coronary artery disease, cardiomyopathy or heart failure.
Potential treatments include beta blockers; a more powerful rhythm drug called amiodarone; implantable defibrillator (ICD); and ablation in selected cases.
Decisions about treatment can be complex and usually require detailed assessment of the underlying heart problem with cardiac catheterisation, echocardiogram and often cardiac MRI.

Amongst the bradycardias, or slow rhythms, we see two major classes, with some people having feature of both. Either the natural pacemaker of the heart slows down (sick sinus syndrome, or sino-atrial disease) perhaps with pauses; or the conducting system between the top chambers (atria) and bottom, pumping chambers (ventricles) is faulty, leading to atrioventricular node block, commonly referred to as heart block.
Both are frequently treated with pacemaker implantation to improve symptoms of breathlessness or dizzy spells and blackout, and to keep patients safe.