Heart Failure and Biventricular Pacemakers
In the normal heart, the lower chambers (ventricles) pump at the same time and in sync with the heart's upper chambers (atria).
When a person has heart failure, often the right and left ventricles do not pump together. And when the heart's contractions become out of sync, the left ventricle is not able to pump enough blood to the body.
This eventually leads to an increase in heart failure symptoms, such as shortness of breath, dry cough, swelling in the ankles or legs, weight gain, increased urination, fatigue, or rapid or irregular heartbeat.
Cardiac resynchronization therapy (CRT), also called biventricular pacing, uses a special kind of pacemaker -- a biventricular pacemaker -- that is designed to help the ventricles contract more normally. It keeps the right and left ventricles pumping together by sending small electrical impulses through the leads.
This therapy has been shown to improve the symptoms of heart failure and overall quality of life in certain patients with severe symptoms that aren't controlled with medication.
What Is a Biventricular Pacemaker?
Leads are tiny wires implanted through a vein into the right ventricle and into the coronary sinus vein to pace or regulate the left ventricle. Usually (but not always), a lead is also implanted into the right atrium. This helps the heart beat in a more balanced way.
Traditional pacemakers are used to treat slow heart rhythms. Pacemakers regulate the right atrium and right ventricle to maintain a good heart rate and keep the atrium and ventricle working together. This is called AV synchrony. Biventricular pacemakers add a third lead to help the left ventricle have a normal contraction when it also doesn't function properly.
Who Is a Candidate for a Biventricular Pacemaker?
Biventricular pacemakers improve the symptoms of heart failure in about 50% of people that have been treated with medications but still have severe or moderately severe heart failure symptoms. Therefore, to be eligible for the biventricular pacemaker, heart failure patients must:
- Have severe or moderately severe heart failure symptoms
- Be taking medications to treat heart failure
- Have the type of heart rhythm problems mentioned above (your doctor can usually determine this using ECG testing)
In addition, the heart failure patient may or may not need this type of pacemaker to treat slow heart rhythms and may or may not need an internal defibrillator (implantable cardioverter defibrillator, or ICD), which is designed to treat people at risk for sudden cardiac death or cardiac arrests.
My Doctor Recommends Combination ICD and Pacemaker Therapy. Why?
People with heart failure who have poor ejection fractions (measurement that shows how well the heart pumps with each beat) are at risk for fast irregular heart rhythms -- some of which can be life-threatening -- called arrhythmias. Currently, doctors use an ICD to prevent these dangerous rhythms. The device works by detecting such a rhythm and shocking the heart back to normal.
These devices can combine biventricular pacing with anti-tachycardia pacing (to slow down the heart rate) and internal defibrillators (ICDs) to deliver shocks as needed. Current studies are showing that resynchronization may even lessen the amount of arrhythmia that occurs, decreasing the times the ICD needs to shock the heart. These devices are improving heart failure patients' quality of life as well as improving their safety.