Daniela Zammit, from the Malta Medical Students’ Association, describes how the life-saving pacemakers work and how they allow patients to lead a fairly normal life.
Every day, the average, healthy heart beats about 100,000 times, sending 2,000 gallons of blood surging through the body. You would be surprised to know that your heart starts beating from just the sixth week of life! Although it’s no bigger than the size of your fist, it has the mighty job of supplying blood to all your organs and tissues through a total of 60,000 miles of blood vessels.
Over centuries, whether in religion, literature or love lyrics, we have associated the heart as working independently from the brain. This is partly true, as the trigger to start beating is found locally in a group of cells called the sinus node or sinoatrial node (SA node), located in the upper part of the heart, that fire off the initial electrical impulses. This internal electrical system controls the rate and rhythm of your heartbeat.
With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As the signal travels, it instructs the heart to contract in a sequence, leading to the coordinated expulsion of blood to the rest of the body.
So what if this electrical system does not function properly? This may result in problems with the rate or rhythm of the heart, known as arrhythmias; the heart can beat too fast (tachycardia), too slow (bradycardia) or with an irregular rhythm.
During such arrhythmias, the heart may not be able to sufficiently pump enough blood to the body, resulting in symptoms such as fatigue (tiredness), shortness of breath or even fainting. If severe, it may also cause loss of consciousness or even be fatal.
In most cases, having a pacemaker will not limit the patient from doing sports and exercise, including strenuous activities
A pacemaker helps to correct such faulty electrical signalling. It is a small device placed in the chest to control abnormal heart rhythms. It can help to relieve some arrhythmia symptoms and allow a person to resume a more active lifestyle.
A pacemaker consists of a battery, a computerised generator and wires with sensors at their tips, known as electrodes. These wires connect the generator to the heart. Put simply, pacemakers monitor the heart’s electrical activity and if detected as abnormal, low-energy electrical pulses are transmitted through the wires to your heart to restore a normal rate or rhythm. Their role is to sense a slow heart beat and to pace i.e. to make sure a suitable rate is achieved, thus proving useful to speed up a slow rhythm (bradyarrhythmia).
Other types of implantable devices include ICDs (Implantable Cardioverter-Defibrillators) and CRTs (Cardiac Resynchronisation Therapy) in order to control an abnormal or fast heart rhythm (tachyarrhythmia), coordinate proper signalling between the upper and lower chambers of the heart (atria and ventricles respectively) and prevent dangerous arrhythmias in disorders such as long QT syndrome.
Pacemakers can be either temporary or permanent. Temporary pacemakers are used to treat short-term heart problems, such as a slow rhythm following a heart attack, during heart surgery or while waiting for a permanent pacemaker to be fitted.
On the other hand, permanent devices are used long-term for persisting heart conditions, most commonly in heart blocks.
Heart block is a disorder where electrical signals are not transmitted efficiently through the heart chambers as a result of ageing, heart attack damage or even certain nerve and muscle disorders.
Other indications include drug-resistant tachyarrhythmias and sick sinus syndrome (SSS), where the ageing heart cannot set the correct pace of the heartbeat from the sinoatrial node or SA node (the generator of the normal sinus rhythm), dangerously alternating between slow and fast rhythms.
A common misconception is that pacemakers, ICDs or CRTs are associated only with the elderly. This is clearly not the case, as children, teens and adults alike can use these devices for congenital heart disease, following heart transplants and inherited conditions such as long QT syndrome.
We have come a long way from the early pacemakers designed in the 1950s. Newer ones can also monitor the blood temperature, breathing rate and other factors, while alternating your heart rate according to your physical activity.
A brighter future
The pacemaker is individually programmed by the specialist according to the patient’s own electrical activity and heart rhythm. It allows him or her to lead a fairly normal life.
However, some lifestyle changes would include avoiding close or prolonged contact with electrical devices or devices that have a strong magnetic field as these may disrupt the electrical signalling of the pacemaker. These include mobile phones and MP3 players, household appliances such as microwave ovens, metal detectors, industrial welders and electrical generators.
Some medical procedures may also disrupt the pacemaker such as MRI, shock-wave lithotripsy for kidney stones and electrocauterisation during surgery.
Wearing a medical ID bracelet may be necessary to alert medical personnel of the pacemaker.
Device envisioned to become size and shape of a vitamin capsule
In most cases, having a pacemaker will not limit the patient from doing sports and exercise, including strenuous activities.
However, full-contact sports such as football and martial arts may be best avoided to prevent damage to the pacemaker or shaking loose the connection with the wires.
Pacemakers need reviewing by a doctor every few months to ensure optimum function.
The future seems even brighter for these patients. The device is envisioned to become the size and shape of a vitamin capsule rather than the bulky traditional pacemaker, allowing it to be fitted directly into the heart muscle – versus today’s usual placement, below the skin next to the collarbone.
They are becoming more advanced and efficient; in some cases even combined with ICDs or CRTs as a single device to serve multiple roles.