Medical Devices for the Heart

Written by: Pooja Kasarapu
Medically reviewed by: Robert Philibert MD PhD
 
For select patients, the use of an implanted device to help the heart function properly is often viewed as the best solution for their heart condition. The reasons for this choice of therapy varies.  Frequently, the recipient of a device may be suffering from an arrhythmia. Arrhythmia is the irregular beating of the heart, which is a condition that stems from irregular electrical pulses. These pulses signal the heart and tell it when to pump.

Alternatively, mechanical dysfunctions of the heart muscle itself may be the problem. Mechanical dysfunction is when certain chambers of the heart do not contract and relax properly. This can result from inherited genetic factors or from immune mediated conditions such as amyloidosis.   Both of these types of vulnerabilities result in the chambers not being able to fully fill up with blood and then contract  release the blood into the next chamber or into the aorta. As a result, the total volume of blood pumped by the heart is reduced.

There are a number of different types of devices that are available:

  • Left Ventricular Assist Device (LVAD)

As the name suggests, this device is for patients whose left ventricle does not contract. The left ventricle has the job of contracting in order to transfer blood into the aorta. When the left ventricle does not function properly, “left sided failure” often results. Ideally, the best solution is to directly address the cause of failure.  But in many cases, repair is not possible and the only option is a heart transplant. In many of these situations, an LVAD can help keep the left ventricle functioning well enough until the patient receives a donor heart.

The LVAD consists of a pump that is placed inside the patient’s upper abdomen. It is connected to the heart and draws blood from the left ventricle. It then pumps blood into the aorta. The pump has another tube attached to it that exits the body through the wall of the abdomen and connects to the battery.  Originally, these devices were quite bulky and required the patient to remain in bed. However, advances in pump and battery technology have enabled the development of portable devices that allow the patient to resume many aspects of a normal life.

  • Pacemaker

A pacemaker does just what its name suggests. It maintains the regularity of the electrical pulses that regulate the contraction of the heart. The most common devices have their key hardware components implanted right beneath the patient’s collarbone.  The resulting bulge from the pacemaker can then be seen as a lump underneath the skin. In this case, the electrical impulses from the hardware are conducted to the heart via electronic leads. In other cases, the pacemaker may be implanted directly into the heart. This type of device is common in patients who have slow heart beats, which can result in insufficient blood reaching the rest of the body.

  • Implanted defibrillator

Like a pacemaker, this device is connected directly to the heart inside the patient’s body. As opposed to a pacemaker, which generally uses lower levels of electrical power, this type of device  acts like an automated external defibrillator (AED). An AED is the device you often see a healthcare professional using when a patient goes into cardiac arrest. They attach pads to the patient’s chest and deliver a shock to the patient’s heart. An implanted defibrillator works in the same way. It analyzes the patient’s heart rhythm and if it reads a potentially fatal rhythm, it will deliver a shock to the heart. If the device is low energy, then the patient should not feel any discomfort when the shock is delivered. If it is a high energy device, there may be sudden pain in the chest when the shock is delivered, but the pain subsides quickly. The Mayo Clinic lists candidates for implanted defibrillators as those who have survived cardiac arrest, have fainted from ventricular arrhythmia and have other heart conditions that may affect the rhythm of the heart.

  • Implantable Cardiac Loop Recorders

This device is not directly therapeutic.  Instead, it provides a great deal of in depth clinical information for the patient’s cardiologist. It is a small device placed right beneath the chest and monitors the patient’s heart rhythm. Unlike the implanted defibrillator, this device does not provide a shock for the patient. Instead, the primary goal of this device is to determine the frequency and the source of arrhythmia in the patient. It is also good for determining the source of strokes. An implantable cardiac loop recorder can work up to 3 years.

If you have an implanted device and are curious to learn more about it, do not hesitate to ask your cardiologist. If your cardiologist prescribes a cardiac device, the prospect of having the device can seem a bit daunting. However, understanding how the device works makes the implantation and subsequent living with the device a lot less worrisome! Patients who are on medical cardiac devices should continue to make good lifestyle choices to support their heart as much as they can. They should also follow their cardiologist’s instructions on proper maintenance of the device, if any.
 
References:

  1. “Types of Cardiac Devices,” NYU Langone Health,https://nyulangone.org/conditions/cardiac-device-management-in-adults/type>
  2. “Implantable Cardioverter Defibrillators,” Mayo Clinic, https://www.mayoclinic.org/tests-procedures/implantable-cardioverter-defibrillators/about/pac-20384692
  3. “Implantable Medical Devices,” American Heart Association, https://www.heart.org/en/health-topics/heart-attack/treatment-of-a-heart-attack/implantable-medical-devices
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