Commonly implanted cardiac devices from various manufacturers are shown. A quarter is used for size perspective. Pacemakers (indicated with blue arrows) are devices used to correct slow heart rhythms. Implantable cardioverter-defibrillators, or ICDs, are indicated with red arrows. ICDs have the ability to treat both slow heart rhythms (like pacemakers) and fast, life-threatening heart rhythms. Note that ICDs are larger than pacemakers as they have to accommodate larger capacitors to deliver a life-saving high-energy shock when required.

This picture demonstrates the difference in thickness between a pacemaker (blue arrow) and ICD (red arrow).

Note also the thin line on the side of both the pacemaker and ICD. This line represents the weld joint of the device to achieve a hermetic seal so the device can withstand fluids in the body. Therefore, when the device needs to be replaced for a weak battery, the entire device needs to be changed, but the existing leads can often be used if functioning normally and intact.

This picture demonstrates various types of leads (insulated wires that connect heart tissue to the pacemaker or ICD). The lead tips shown here are connected to the heart muscle itself. The end of the lead that connects to the pacemaker or ICD is not shown. The red arrow demonstrates a pacemaker lead. Notice the corkscrew-shaped helix that extends from the tip of this lead. This mechanism is used to secure the lead into the heart muscle. The blue arrow also shows a pacemaker lead, but with a different way of securing the lead in the heart. The tined lead tip passively catches in the lattice-like trabeculations of the heart like a grappling hook to keep the lead in place. The final lead shown (black arrow) is an ICD lead. Notice it is thicker than the other leads and contains an external coil (yellow arrow), which is used in the circuit to deliver a high-energy shock to terminate life-threatening arrhythmias. This lead also uses an active mechanism; however, the helix is not deployed, which is still in the lead tip.

A diagnostic catheter (shown) used to record electrical signals in the heart and pace the heart. Note the metal rings at the tip of the catheter (termed electrodes). In this case, four electrodes present, making this a quadripolar catheter. These catheters are commonly used in electrophysiology studies to study the heart’s electrical system.

Another type of diagnostic catheter, commonly known as a “lasso” catheter, is shown. It can be bent or steered, and the circumference can be adjusted allowing it to placed in specific places in the heart.

This catheter is usually placed in the pulmonary veins for a pulmonary vein isolation procedure, or more commonly referred to as an atrial fibrillation ablation.

Another type of catheter, called an ablation catheter, is shown here. This catheter performs all the functions of a diagnostic catheter, but is also used to destroy small areas of abnormal heart tissue by burning or freezing this tissue from the tip of this catheter (a procedure known as an ablation). Note the maneuverability of this catheter to facilitate delivering energy very precisely.

Contemporary ambulatory heart rhythm monitors record electrical signals from the heart during daily activities. They trigger automatically when an abnormal heart rhythm is detected or manually by a patient with symptoms (loop recorder). They can also be used to record continuously for a specified period of time (Holter monitor). The wires held in this picture connect to electrodes which connect to a patient’s skin using an adhesive and a sensor which communicates with the cellular phone (also shown). The cellular phone then automatically calls a central location that processes the heart rhythm for your physician to interpret.

Shown in this picture is an implantable loop recorder. It works on the same premise as the external loop recorder with both automatic and manual triggers, but is implanted superficially under the skin. There are no leads that enter the blood vessels or the heart. The latest models can be left in for three years if necessary. These devices are then removed when enough information is obtained or when your physician and you agree an adequate period of monitoring has been reached.