Implanted Heart Rhythm Devices

The heart is a remarkable muscle pump, the central part of the circulatory system, which continuously supplies nutrients and oxygen to all other organs. Its action is regulated by the electrical system, which causes the chambers of the heart to squeeze and relax in an efficient, synchronized manner (50 to 80 beats per minute in adults at rest). During heavy physical activity, it is essential for the pump keep up with the demand – one of important responses is increased heart rate.

Symptoms That May Indicate a Need For a Heart Rhythm Device Monitor

Many heart disease processes can affect the electrical system. Even if the strength of the heart muscle remains preserved, abnormalities of the electrical system may severely compromise the overall function.

A healthy lifestyle is very important to protect the electrical system of the heart. Once it gets damaged, the heart may have little ability to recover. The signs of various forms of the disease may be highly variable, depending on the specific injury, but some include:

• Slow heartbeat, leading to fatigue or passing out
• Irregular heartbeats
• Decreased pump function leading to blood clots
• Heart failure and stroke
• Abnormally fast heart rate, leading to heart failure

Types of Implantable Heart Devices

Treatment usually involves lifestyle changes and medication. A minimally invasive procedure, cardiac ablation, can be used to treat many abnormal fast or irregular heartbeats. In cases where the electrical system is diseased to the point where these measures are not enough, implanted heart rhythm devices can be used to support the electrical system of the heart.

Implantable Loop Recorder

Some abnormal heartbeats only present infrequently and may be difficult to identify. The patient may have no symptoms, and all other heart tests may be normal between the episodes. Short term heart rhythm monitoring can be pursued with wearable monitors. If long term monitoring is required, an implantable loop recorder can be used. The device (the size of two matchsticks placed side by side) is placed below the skin on the left side of the chest and provides continuous heart rhythm monitoring for up to 4 years.

The implant procedure takes a few minutes and does not require sedation. There are no activity limitations with an implanted loop recorder. The device is monitored remotely using wireless communication.

Pacemaker

A slow heartbeat can be caused by abnormalities of electrical impulse generation (diseases of the sinoatrial node – electrical center of the heart), or when the electrical signals cannot reach the lower chambers of the heart (heart block). Patients usually experience fatigue, lightheadedness or may pass out repeatedly.

A pacemaker can deliver gentle electrical stimulation to the heart and increase the heart rate. Pacemakers can be implanted below the skin below the collarbone and the device is connected to the heart with insulated wires (leads). Depending on the disease process, from one up to three wires are used. In certain cases, a miniature pacemaker can be used, which can be directly implanted into the heart.

The implant procedure usually takes an hour, and sedation and local anesthesia are used. Most patients can go home the same day after the implant. After recovery, no specific restrictions are needed with usual daily activities. The battery lasts 10-12 years and replacement requires a procedure similar to the implant.

Implantable Defibrillator

Abnormally fast heartbeats can lead to sudden death. These are usually associated with severe diseases of the heart muscle, or genetic heart conditions. Medications and lifestyle changes decrease the risk, however, sudden death may still occur in patients who do not respond well treatment.

When the heart suddenly stops due to an abnormally fast heartbeat, death occurs in a few minutes unless prompt treatment is delivered (defibrillation – an electric shock to the heart). An implantable defibrillator can be used in high risk patients – the device continuously monitors the heart rhythm and delivers a life saving shock if a dangerously fast heartbeat occurs. The implant procedure, longevity and remote monitoring are similar to a pacemaker. In cases where a pacemaker function is not needed, the defibrillator can be implanted on the left side of the chest. This device does not require leads placed inside the heart and may be a lower risk option for younger or physically very active patients.

Cardiac Resynchronization Therapy

Besides abnormally low or high heart rate, some heart diseases affect the proper timing of the heart cycle. If the disease causes electrical delay inside or between the ventricles (main pumping chambers of the heart), the weakened heart function can deteriorate further. Patients usually present with signs of worsening heart failure.

Cardiac resynchronization therapy uses leads connected to both sides of the heart to decrease the activation delay and improve heart function. The device can be a multi-lead pacemaker or defibrillator, depending in the disease process leading to the electrical issue. The implant process and recovery are similar to a pacemaker. Most patients feel improvement in their heart failure symptoms shortly after cardiac resynchronization therapy is initiated.

Cardiac Contractility Modulation

Some patients experience signs of heart failure due to weakened heart function, even with normal heart rate and without electrical delay – in these cases, a pacemaker or cardiac resynchronization therapy cannot be used. A specific method of electrical stimulation of the main chambers of the heart (cardiac contractility modulation) can improve the strength of the heart contraction and improve heart failure symptoms. The device is similar to a pacemaker, with similar implant process and longevity.

Learn more about heart conditions and our CHI Health Heart Institute.