What Types Of Implantable Devices May Help People With Cardiomyopathy?

Cardiomyopathy is a group of heart muscle diseases that can reduce the heart’s ability to pump blood. It encompasses diverse disorders that cause changes in the structure of the heart muscle — like changes in size, shape or the thickness of the muscular walls. While symptoms of cardiomyopathy vary, most patients don’t show any symptoms until the heart is no longer able to meet the body's demands, a condition known as heart failure. Other life-threatening complications, like stroke and sudden cardiac death, can also occur. 

What are arrhythmias and how can they be dangerous?

Any abnormality in the timing and/or the patter of heart rhythm is called arrhythmia. 

Your heart consists of four chambers. Two upper chambers called atria collect blood and pass it to the lower chambers called the ventricles. The right ventricle pumps blood to the lungs, where it gets oxygenated, while the left ventricle pumps the oxygen-rich blood from the heart to the rest of the body. For that to occur, heart contractions need to happen in a tightly ordered manner. Chambers contract when they receive an electrical impulse through the heart’s electrical network. Special groups of cells called natural pacemaker cells send electrical impulses that dictate heart rhythm. 

Arrhythmias occur when there’s a disruption in electrical signaling. Normally, your heart beats 60 to 90 minutes in a regular rhythm called sinus rhythm. In arrhythmia, the heart can beat too fast (tachycardia), too slow (bradycardia) or erratically (fibrillation). Depending on where they originate, arrhythmias can be:

• Supraventricular (originating from above the ventricles). 
• Ventricular. 

​​Two types of ventricular arrhythmias can be particularly dangerous: ventricular tachycardia and ventricular fibrillation. Ventricular tachycardia (VT) is when the ventricle contracts too fast, out of rhythm with the atria, and it can lead to dizziness and fainting. In ventricular fibrillation, the ventricles receive erratic, rapid impulses which cause them to quiver rather than pump blood; a medical emergency that requires immediate attention to avoid a fatal outcome. ICDs are used to treat these two types of arrhythmia.

In cardiomyopathy, arrhythmia can be a result of structural changes in the heart, or a consequence of heart failure. In heart failure, the heart tries to compensate for its reduced ability to pump blood by pumping faster (tachycardia). Arrhythmias can also happen as a complication of procedures used to treat cardiomyopathy, like septal myectomy or alcohol septal ablation, procedures used to treat hypertrophic cardiomyopathy.

How ICDs work and who needs them?

An implantable cardioverter-defibrillator (also called automated implantable cardioverter-defibrillator, AICD) is a small, battery-powered, device that monitors and corrects your heart rhythm when needed. It’s primarily used to correct life-threatening ventricular arrhythmias, like VT and V-fib. Additionally, it can store information that can help your physician improve your treatment.

ICDs are implanted under your skin, just under your left collar bone, and they have two parts:

• ICD generator. This part has a computer chip with programmable software, along with the battery and the capacitor. It monitors and analyzes the heart rhythm by comparing contractions of the upper and lower chambers of the heart and the regularity of contractions. In this way, it can discriminate between ventricular arrhythmias (VT and V-fib) and other types of arrhythmia. 
• Wires (leads). Wires transport electrical signals from the generator to the heart; depending on the number of wires, ICDs can be single-chamber (one wire leads to the right ventricle), dual-chamber (two wires leading to the right atrium and the right ventricle) or biventricular (third wire leads to the left ventricle).

Modern types of ICDs can do three things:

• Pacing. When the ICD detects VT, it takes over the electrical signals that control contractions by giving small, fast, electrical impulses to control the arrhythmia. Older versions of ICDs don’t have this feature.
• Cardioversion. If pacing is not successful in treating VT, the ICD sends a small electrical shock that converts the heart rhythm back to normal (sinus rhythm).
• Defibrillation. When the ICD detects that your ventricles are beating erratically (V-fib) it sends an electrical shock called counter-shock that affects a large portion of the heart muscle and stops the arrhythmia. After that, natural pacemaker cells establish a sinus rhythm. This shock can be painful and uncomfortable, but it only lasts for a moment.

ICDs are used for patients who are at high risk of dangerous arrhythmias. Implantation is a simple procedure that requires a one-day hospital stay, and the battery usually lasts around six years. Overall, studies show that ICDs are as good or better at improving the quality of life than antiarrhythmic drugs. Physical adjustment to implantation is often minimal, with only rare cases of bacterial and fungal infections being reported.

However, some patients struggle with psychological adaptation. One study showed that up to 38 percent of patients developed anxiety, and up to 41 percent had symptoms of depression. This might be correlated with how patients perceive their condition rather than the ICD itself. Some patients feel vulnerable and restrain from physical and intimate activities. However, there’s no medical reason for this. Almost all types of physical activity that don’t put a strain on the shoulder or the area where the ICD is implanted can be safely done.

How can pacemakers help people with cardiomyopathy?

Pacemakers are in many ways similar to ICDs. In fact, an ICD can be considered a special type of pacemaker with additional features. Like ICDs, pacemakers have a generator and electrode that deliver electrical impulses to your heart. While ICDs deliver electrical impulses only when needed, pacemakers usually take over the role of natural pacemaker cells that normally dictate heart rhythm. Therefore they are used when the heart’s natural pacemaker is not fast enough (bradycardia), or when a person has a heart block-a problem in conduction of electrical signals. 

They can be implanted temporarily, for example during or after heart surgery or heart attack, or permanently. It’s inserted similarly as ICD, under your left collar bone. A fluoroscope (imaging technique) is then used to lead wire(s) through your vein and into your heart. Based on the number of wires (leads) it can also be a single chamber, dual chamber or biventricular.

For cardiomyopathy patients who have reached heart failure, a biventricular pacemaker is used. It’s used for the cases of so-called ventricular dyssynchrony, a condition in which the right and left ventricle don’t contract simultaneously, which is often the case in heart failure (in 25 to 50 percent of patients). This is called cardiac resynchronization therapy and it can help with symptoms of heart failure like dizziness and fatigue. 

Treatment for progressed heart failure: Ventricular assist devices 

Ventricular assist device or VAD is a mechanical pump that helps your right (RVAD) or left (LVAD) ventricle pump blood when they’re no longer efficient in pumping on their own. Generally, VADs are the last option when all other types of treatment haven’t been successful. 

They are used in three types of cases:

• For patients awaiting a heart transplant.
• As “a bridge to recovery”. In patients whose heart failure is temporary, VAD is inserted until the heart can pump again on its own.
• As “destination therapy”. Destination therapy is to say that not much can be done in terms of treating and improving or stopping heart failure, but the patient's quality of life can be improved. This is the case in people who are in end-stage heart failure but are not eligible for a heart transplant due to their age (usually people older than 65) or medical conditions. In some cases, VAD can improve a person’s condition so they can become a candidate for a heart transplant. 

Insertion of VAD requires open-heart surgery that comes with several risks.