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Decoding the Differences Between Defibrillators & Pacemakers

Banner image having a red heart shape with line of cardio gram and stethoscope on pink background illustrates the difference between defibrillators and pacemakers.
January 29, 2024
by Dr. Karthigesan

It’s hard to imagine where the medical world would be without technological advancements. The incredible progress has made it possible to maintain cardiovascular health better than ever.

Today, cardiac patients have access to lifesaving devices like defibrillators and pacemakers to maintain a healthy heart rhythm. However, there is a misconception that both devices are the same. This article aims to decipher how both devices differ in terms of role and function in saving your heart.

What is a Defibrillator, & How Does It Work?

The defibrillator is a heart-rhythm-monitoring device designed to administer a lifesaving shock to regulate a potentially dangerous irregular heartbeat.

Such irregularities can occur when the heart pumps too fast and contracts even before the ventricles are filled with blood, potentially leading to cardiac arrest. The defibrillator is designed to detect irregularities and generate a shock to regulate the rhythm and prevent further complications.

Functioning of a Defibrillator

The Implantable Cardioverter Defibrillator[ICD] is implanted beneath your collarbone using a minimally invasive procedure. The ICD is roughly the size of a pager. Defibrillators include a generator and leads that detect rhythms and deliver appropriate shocks to the heart. The ICD generator comprises three key components:

  • Capacitor
  • Computer chip or Processor
  • Battery

Leads are attached to the generator and run through a vein to the heart. They sense electrical activity and deliver the shock. ​​An electronic circuit within the generator interprets the electrical signals and determines when to deliver a shock.

Generally, doctors recommend defibrillators to rectify fast heart rhythms. However, the device can also serve as a pacemaker to regulate slow or weak heartbeats.

Who Requires a Defibrillator?

Your doctor may recommend a defibrillator if you have any of the following medical conditions:

  • High risk of arrhythmia-induced death
  • Very poor heart function (Low EF)
  • History of cardiac arrest
  • Cardiac diseases like Cardiomyopathy

You may also require a defibrillator if you are prone to genetic issues causing ventricular arrhythmias or the fast heart rhythm generated from the ventricles. The conditions include:

  • Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
  • Long QT Syndrome
  • Hypertrophic cardiomyopathy (HCM)

What Are the Types of Defibrillators?

There are different types of defibrillators, each with its own unique function. However, the three most commonly used types are:

  1. WCD or Wearable Cardioverter Defibrillator, which is worn like a vest under your clothes. The sensors are attached to the chest area to monitor your heart rhythm as you go about your routine work.
  1. ICD or Implantable Cardioverter Defibrillator, which, as the name implies, is surgically implanted into your body (below the collar bone).
  1. AED or Automated External Defibrillators are used in emergencies when someone is experiencing a cardiac arrest. This device automatically diagnoses the heart rhythm and delivers a shock if necessary to save the person's life.

What Are the Different Types of ICDs?

  1. Traditional Intravascular ICD - The defibrillator is placed below the collar bone, and the leads are positioned inside the cardiac chambers.
  2. Subcutaneous ICD[S-ICD] - The defibrillator is placed in the axillary[below the armpit] region, and the lead is placed parallel to the sternum.
  3. Extravascular ICD[EV-ICD] -The defibrillator is placed in the axillary region, and lead is placed in the substeral region.

What Happens During a Defibrillator Implantation?

The defibrillator implantation is a minimally invasive procedure requiring no more than an hour. Most often, the procedure requires only a local anaesthesia administered at the incision site.

In most people, the defibrillator is placed just below the left collarbone. In rare cases, it may be placed under the sternum or along the ribs in adults or in the abdomen in infants.

Your doctor will use imaging to help guide the placement of the ICD leads. These leads are thin wires threaded through a vein near your collarbone and into specific chambers of your heart. Some newer types of leads may be placed under the skin. Once the leads are positioned, your doctor will test the ICD to ensure it's working properly before closing the incision. You may be able to leave the hospital after the anaesthesia wears off.

How Do Defibrillators Save Your Life?

Defibrillators can be life-saving devices for people with specific heart conditions. While implantation involves some rare risks like bleeding and infection, many people experience improved quality of life after successfully receiving a defibrillator.

What is a Pacemaker & What Is Its Function?

Like the defibrillator, the pacemaker is also a battery-operated device, roughly the size of a matchbox. There are two types of pacemakers:

  • Internal or permanent pacemakers that function for the rest of your life.
  • External or temporary pacemakers.

The fundamental function of a pacemaker is to regulate Bradycardia or slow heartbeat by sending electrical impulses to the heart. However, it is also recommended for patients with Tachycardia or fast heartbeat. Your doctor may also recommend a pacemaker if you:

  • Have an erratic heartbeat
  • Take medications that reduce your heart rate
  • Have undergone an Ablation procedure and require the device to regulate your heart rhythm.

Functioning of a pacemaker

By make, the pacemaker is quite similar to a defibrillator. A traditional pacemaker has the following components:

  • A generator housing the battery and circuitry
  • Wires or leads that are connected to your heart via the veins. These leads carry the electrical impulse to the heart.
  • Electrodes or sensors that monitor your heart and deliver electrical impulses when necessary.

The pacemaker is designed to respond to your heart rate, which is constantly monitored by the sensor within the device. It continuously sends steady, low-energy electrical impulses to help maintain a regular heartbeat. The speed at which the device sends electrical impulses to your heart is called the Pacing rate.

What Are The Types of Pacemakers Available?

Although various types of pacemakers are available, your doctor will recommend the right one after determining your cardiac condition. The four most commonly used pacemakers are:

  • Single-lead pacemaker - It has one lead, which is placed in the right ventricle or the right atrium of your heart.
  • Double-lead pacemaker - It has two leads. One is placed in the right ventricle and the other in the right atrium.
  • Biventricular pacemaker or Cardiac Resynchronisation Therapy (CRT) - It has three leads. While two are attached to the right and left ventricle, the third is connected to the right atrium. Together, the leads facilitate the coordination of signals between both ventricles.
  • Leadless Pacemaker - It is like a capsule in size and inserted from the groin via the femoral vein and placed inside the right ventricle.

Pacemaker Implantation: How it Happens

The pacemaker implantation is a minimally invasive procedure that takes no more than an hour. You may need to spend a few hours or stay overnight at the hospital before going home.

  • The doctor administers local anaesthesia at the site where the pacemaker is implanted.
  • Your cardiologist used X-rays or echocardiography to thread the leads through your chest, neck, or thigh veins to access the heart chambers.
  • After the leads are placed in the right location, your doctor makes a small incision under the skin in your abdomen or chest to place the pacemaker.
  • After connecting the leads to the generator, your doctor tests the pacemaker to ensure it functions properly.
  • The incision is finally closed with sutures.

How the pacemaker benefits your heart health

The pacemaker plays an incredible role in saving people's lives with irregular heart rhythms. The benefits include:

  • Better quality of life
  • Shorter hospital stay
  • Uncomplicated surgery

A pacemaker implant can be associated with the following risks in rare cases:

  • Infection
  • Bleeding
  • Abnormal heartbeat
  • Interference of devices like magnets and cell phones with your pacemaker.

Defibrillator Vs. Pacemaker: What’s the Verdict?

First of all, defibrillators and pacemakers are NOT the same. Although they both are cardiac devices, the defibrillator regulates life-threatening heart rhythms that can potentially cause sudden cardiac arrest. Pacemakers, conversely, generate electrical impulses to regulate a slow or irregular heartbeat.

However, your doctor may recommend a suitable device based on your cardiac condition. Currently, there are devices capable of functioning as a defibrillator and a pacemaker. Whatever the device, it's important to keep in mind that they safeguard your life, although they come with some rare risks like:

  • Infection
  • Blood clots
  • Punctured or collapsed lung
  • Damaged blood vessels and nerves

Seek Expert Guidance from Dr. Karthigesan

Dr. Karthigesan is one of the most reputed doctors for heart rhythm treatment in Chennai. He is a pioneer of cardiology, device therapy, and electrophysiology and has performed thousands of cardiac device implantation procedures to save countless patients.

Schedule your appointment with Dr. Karthigesan for defibrillator placement in Chennai. Get the best cardiac treatment from an expert in permanent pacemaker implantation in Chennai.

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