What is cardiac electrophysiology?

Most simply, cardiac electrophysiology is the field of medicine concerned with the study and treatment of the heart’s intrinsic electrical activity.

Electrical activity - the movement of charged particles down gradients and across barriers - forms the basis of many living processes including nerve function, contraction and relaxation of muscles, peristalsis of the gut, and movement and coordination of the heart. Each heart beat is the product of a highly choreographed sequence of electrical events that allows a heartbeat to (nearly) always start in the same place and spread in the same way through the heart, up to 100,000 times a day in a healthy human.

The route of spread of the heartbeat is important, because as the beat spreads, so the heart twitches into life - moves - to propel blood forward through the body via arteries and veins. If the heart’s electrical activity is not properly coordinated, then the mechanical function of the heart - the pumping action - will be compromised. When everything is working as it should, the main cardiac pumping chambers (the ventricles) squeeze and rotate upwards and backwards in the chest to push blood out from apex to base of the essentially connical cardiac structure. This process is highly efficient, producing maximum movement of blood around the body for minimum expenditure of energy by cardiac muscle. Pretty much any alteration of the heart’s electrical activity away from this normal arrangement produces a decrease in efficiency of the pumping of blood, sometimes dramatically so.

An extreme example is when a cardiac chamber’s electrical coordination breaks down entirely, and becomes random and chaotic, so-called “fibrillation”. If fibrillation arises in one of the upper chambers of the heart then the immediate mechanical effects may be limited, as in fact the upper chambers contribute relatively little (less than 10% in most healthy human hearts) to the total cardiac output of blood. The patient may feel unwell; they may be aware of the heart beat becoming dysregulated and irregular, and there are some risks to this continuing for long periods.

However, if one of the main pumping chambers - ventricles - begins to fibrillate then the effects are much more dramatic: blood movement by the heart will quickly cease, with rapid death of the patient following.

Happily, ventricular fibrillation is rare! It is, however, the leading reason why people die suddenly during a heart attack: the interruption of blood supply to just a small portion of the heart’s total muscle can lead to chaotic electrical activity which rapidly spreads through the entire ventricular muscle mass, ending in rapid loss of cardiac output and death. The field of cardiac electrophysiology therefore interacts extensively with other fields in cardiology including the treatment of diseases such as heart attack, diabetes and high blood pressure, all of which increase the tendency of the heart to abnormal rhythms such as fibrillation.

Most of the practice of cardiac electrophysiology, however, is less dramatic than this. Typically abnormal heart rhythms are a lot more stable - and survivable - than ventricular fibrillation, and typically treatments focus on controlling symptoms and normalising the life expectancy of the patient. In the vast majority of patients that I see in clinic, this is eminently achievable. 

This is what makes being a cardiac electrophysiologist such fun!

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You can read more about arrhythmias and other cardiac problems on the patient information pages of my Kent Heart Clinic practice at https://www.kentlondoncardio.com.

Location: Ashford, UK

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