Artificial Cardiac Pacemakers to make your heart go on!

A beating heart and a breath of fresh air mean so much to a living person, simply because these are the hallmarks of life! While the last natural breath taken can be made to continue on an ICU bed with the help of a ventilator, the last natural beat of the heart need not mean death. For, the advances made in cardiology over the years have made it possible to help the heart go on even when the electrical circuitry of the heart has failed. These precisely are the  Artificial Cardiac Pacemakers or simply Pacemakers, to make your heart go on!

Before we go into understanding this modern day ‘God – devices’ it would be interesting to see how the heart is wired.

The conduction system of the heart:

In order that this receiving and pumping of the heart is carried out in a well-coordinated manner, the heart is wired with a very intelligent conduction system. This conduction system sees that the chambers of the heart beat in precise succession, so that there is no mixing and turbulence of the streams. The wiring begins with an impulse generator called the SA node which is situated in the right atrium. It sends impulses to both the atria which then converge at a gate junction between the atria and ventricles which is called the AV node. This AV node delays the impulse a bit so that the ventricles are activated after an adequate filling time. The conduction system them bifurcates into the left and right bundles to supply the corresponding ventricles. The accompanying animation can give you a good idea of how the heart is wired.

Where can problems arise?

Now, there can be problems at two important points. One, at the SA node, where the impulse is actually generated and two at the AV node where there could be an abnormally long delay or even total blockage of the electrical flow to the ventricles. In the first case, the disease is usually called a ‘Sick Sinus Syndrome’ while the second case is called the Atrio-ventricular or AV block. A persistent third degree or a Complete AV block is the one which needs external interventions to keep the heart and life go on.

So what are Artificial Cardiac Pacemakers?

Artificial Pacemakers are electronic devices which take over, modify or support the faulty electrical circuit of the heart. Over the years, there have been significant advances in these pacemakers so that these artificial devices are trained to closely mimic the natural pacemaker of the heart.

A Pacemaker usually has 2 important parts. The Pacemaker Generator and the Pacemaker Leads. The generator is a small box which has the batteries and the microprocessor which generates the electrical impulses in a pre-programmed fashion .The leads are wires which connect the Pacemaker Generator with the heart.

A Pacemaker can be designed to ‘sense’ and ‘pace’ the electrical circuit of the heart.  Similarly it can be designed to deliver impulses in a fixed manner or in a flexible way as per the requirement. It can be used in a single chamber or two chambers. All in all, there is a pacemaker designed in alignment with the exact nature of the problem in the electrical system of the heart. Your doctor will choose the best possible option for the problem in the patient.

How are Pacemakers installed in the body?

The pacemaker implantation involves a minor surgical procedure in which the Pacemaker Generator is placed in a pocket under the skin in the area below your right or left collar bone. The wires or the leads are passed through a vein into the right sided chambers of the heart. This is done under a low dose x ray or fluoroscopic guidance. The pacemaker generator is programmed according to the needs of the patient and the nature of the electrical problem.

As a preparation for this surgical procedure, the patient may be asked to use a depilatory agent to remove the hair on the chest before the procedure. Shaving of the chest hair is being discouraged for the risk of infection at the site. An antibiotic is usually administered a few hours before the procedure.

Once the procedure is complete, adequate care of the wound is important. A Pacemaker Card is provided to the patient which mentions the patient data (Symptoms, Etiology) , pacemaker center, lead type and IPG( rate, date of implantation, manufacturer, type). The patient should always carry this card along.

Living with a pacemaker:

As the pacemaker helps overcome the wiring problems of the heart, some minor lifestyle modifications are advisable.

1. Heavy sporting activity or high level of exertion is to be avoided.
2. The Pacemaker Generator box will always be felt on one side below the collar bone and could cause discomfort while wearing seat belts.
3. Any kind of activity in an intense magnetic field is to be avoided. With this respect, it is important that Magnetic Resonance Imaging is not possible with most of the Pacemakers in place. However recently MRI friendly devices have been introduced which have a few limitations.
4. Electronic devices like headphones, portable music players which have magnets can cause hindrance in the functioning of the Pacemaker if brought within 1 inch distance of the device. Most of the cell phones less than 3 Watts have no interference with the pacemaker function.
5. Before performing certain surgical procedures, it is important to inform about the pacemaker as before certain procedures, an antibiotic may be necessary because of the pacemaker in place.

Pacemaker Care:

After the pacemaker has been implanted, the patient is advised a regular pacemaker care. The patient is advised to see the cardiologist every 6 months to check for the function of the pacemaker. A 2 D Echocardiography is advisable every 1 to 2 years as sometimes, artificial pacing can weaken the contractile power of the ventricles.

Sudden tachycardia (increased heart rate) in a patient is a rare complication which is called a ‘Pacemaker Mediated Tachycardia’. This just requires re-programming of the device. Complications like perforation of the heart muscle are extremely rare with expert hands.

As the pacemaker works on batteries, replacement of the batteries or the device is a ritual needed after a certain period of time depending upon the make and type of the pacemaker. Your cardiologist will inform you about the battery life. As most of the pacemakers work on the principle of ‘on demand’ stimulation, the battery life depends upon the number of times the pacemaker is required to discharge impulses.

The procedure of changing the Pacemaker Generator to change the batteries is simpler as compared to the procedure of implanting a new device.

Pacemaker with additional functions and advanced technology:

In patients with advanced stages of heart failure, at times, the right and the left ventricles do not contract in synchrony. This leads to further worsening of the symptoms. In such cases, carefully identified on the basis of symptoms, ECG findings and 2 D Echocardiography findings a technique called Biventricular pacing or Cardiac Resynchronization Therapy (CRT) has shown to be very effective in increasing the longevity. When this CRT is used only for pacing it is called CRT-P and when the device is designed to give electrical shocks (Defibrillation) in the event of life threatening arrhythmias, it is called CRT-D or Implantable Cardioverter Defibrillator (ICD)

Can an artificial Pacemaker really replace the natural one?

It is obvious to have a doubt in mind, “will this artificial pacemaker create the same change in my heart beat, which I once used to get on seeing my spouse!” Well why not!?

Recently considerable advances have been made in developing a ‘Dynamic’ Pacemaker which is responsive to the body metabolism and emotions. Technology is attempting to give you as naturally functioning devices as possible as you natural pacemaker.

After all the heart must go on…