Implantable Cardiac Devices - Types, Benefits, and Risks

Introduction

The human heart has an electrical system that helps in regulating heart rate. The regular electrical activity of the heart helps pump the heart and maintain a steady rhythm.

Diseases that affect the heart's electrical system result in abnormal rhythm and cause irregular heart rhythms or arrhythmia. Implantable cardiac devices help in regulating the heart rhythm and improve heart function.

What Are Implantable Cardiac Devices?

Cardiac implantable devices include

• Cardiac pacemakers.

• Implantable cardioverter defibrillator (ICD).

• Biventricular pacemaker.

• Cardiac loop recorders.

The devices are battery-operated or electronic devices designed to regulate heart rate and treat heart rhythm disorders. The cardiac devices are implanted under the skin of the chest. It is inserted through a non-invasive surgical procedure.

What Are the Types of Implantable Cardiac Devices?

Permanent Pacemaker:

The heart's natural pacemaker is called the sinoatrial node, which sends electrical signals to the heart to initiate the contraction and pumping of the blood in the heart. In some patients, the electrical activity is affected, and the natural pacemaker will not work properly. This can lead to the absence of electrical impulses and abnormal heart rhythm. A permanent pacemaker is a device implanted under the skin of the chest and sends electrical signals to beat the heart regularly. These battery-operated devices have two parts: a battery-powered pacemaker and a lead connecting to the heart. The types of pacemakers include

• Single Chamber Pacemaker - In this type of pacemaker, the signals are sent to only one chamber of the heart, the ventricle.

• Dual Chamber Pacemaker - Here, the electrical signals are sent to two heart chambers, one atrium and one ventricle.

• Biventricular Pacemaker - The electrical signals are sent to three heart chambers. This type of pacemaker is used to treat heart failure, also called cardiac resynchronization therapy.

• Leadless Ventricular Pacemaker - It is free of leads, a one-piece device directly implanted in the heart. It is minimal in size, with a self-contained generator and electrode systems.

Automated Implantable Cardioverter Defibrillator (AICD or ICD):

An automated implanted cardioverter defibrillator is inserted under the skin on the chest.

The ICD monitors the heart rhythm for 24 hours a day and sends impulses to regulate the heartbeat if required. When the heart rate is very slow, an ICD sends electrical signals to regulate the heart rate, similar to a pacemaker. Similarly, when the heart beats fast, the ICD gives electric shocks to slow the heart rhythm. ICD has two parts: the generator box and the leads. The device is on the left or right side of the chest. If the patient has a fast, abnormal rhythm history, that leads to an emergency. The doctor might suggest ICD. They come in various types.

Implantable Loop Recorder:

It is an implantable device that continuously records the brat for up to three years. It is also known as a cardiac events recorder. It records the heartbeat while doing daily activities. The device is placed just to need the skin of the chest through a minor surgical procedure.

It is given in patients with a regular heartbeat, called arrhythmia, and patients with unexplained stroke or fainting. This device can record the changes in a heartbeat for a long period that other heart recording devices might miss. This helps the doctors to make a proper diagnosis and treatment plan.

The implantable loop recorder is recommended for patients with a high risk of stroke. The placement of this loop recorder does not interfere with day-to-day activities. It does not have patches or wires and is safe while bathing or swimming. It is considered safe during a magnetic resonance imaging (MRI) procedure.

What Are the Benefits of Implantable Cardiac Devices?

• ICDs treat dangerously fast and irregular heart rates.

• Continuously monitors heart activity and restores normal functioning.

• Lowers the risk of death from cardiac arrest more than other medications.

• Long battery life of the devices. The ICDS is designed with lithium batteries that can last up to seven years.

• Other clinical conditions that benefit from ICD include a history of coronary heart disease and heart attack.

• ICD can benefit from maintaining heart rate in conditions with enlarged heart muscle.

What Are the Risks Associated With Implantable Cardiac Devices?

1. The surgery for implantation of ICD may cause infection at the surgical site.

2. Sensitivity to the implant device material.

3. Failure to provide therapy when needed.

4. Giving extra therapy when not in need.

5. ICD leads may damage blood vessels.

6. Bleeding around the heart.

7. Blood leakage through the heart valve.

8. Collapsed lungs.

9. Movement of the implanted devices or leads.

10. When it comes in contact, there are limitations concerning magnetic and electromagnetic radiation, gas, and electric power appliances.

11. Medications are needed to regulate the Heartbeat and to reduce the risk associated with an ICD electrical storm.

12. An electrical storm is an emergency when three or more ventricular arrhythmias occurs in a short period. Usually, one shock is required to restore a regular heartbeat. If more than one shock occurs in 24 hours, patients have to seek emergency medical help.

13. Following the implant surgery, the surgical site might be swollen and tender for a few days.

14. Aspirin and Ibuprofen are contraindicated as they may increase the risk of bleeding.

15. The patient should be dropped from vigorous activities, heavy lifting exercises, and strenuous exercise programs.

16. In patients with ICD to treat ventricular arrhythmia, driving a vehicle will increase the risk of shock.

17. If the patient is terminally ill, the ICD has to be deactivated. If not, they will continuously deliver shocks.

18. It is essential to prevent unwanted shock by turning off the device. Turning off the device will not stop the heart.

19. Electrical interference with an ICD is rare. However, the patient is advised to take precautions.

20. Patients in airports or other security systems use hand-held metal detectors, which interfere with the implantable device. So, always request a manual search.

21. Always carry medical proof to show the presence of an implantable cardiac device, mainly for security reasons.

Conclusion

The implantable cardiac devices are used to restore electrical activity and maintain normal cardiac activity. The ICDs reduce the risk of heart attack and help in proper diagnosis and treatment plans. It is important to follow the doctor's instructions and should be aware of things that can interfere with the functioning of ICDs.