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Cardiac Resynchronization Therapy


  • Cardiac resynchronization therapy (CRT) treats problems with how your heart beats. CRT is also called biventricular pacing. Your heart has two upper chambers (rooms) called atria, and two lower chambers called ventricles. Your heartbeat is synchronized when all areas of your heart beat together properly. During each heartbeat, electrical activity causes your atria to contract (squeeze) first, followed by the ventricles. When the chambers of your heart do not beat as they should, it is called dyssynchrony. When dyssynchrony occurs, your ventricles may not pump enough blood and oxygen to your body. Blood may flow back from your ventricles to your atria. You may have trouble breathing, tire easily, and have swelling in your legs and feet.
    Anatomy of the Heart
  • Heart failure and electrical activity blockages in your heart may lead to dyssynchrony. Dyssynchrony often occurs in the left ventricle, causing it to contract later than it should. For CRT, a pacing device (small battery-powered machine) is implanted under your skin, in your chest. The pacing device has leads (wires) that attach to certain areas in your heart. This device uses electrical energy to fix the timing of your heartbeat. CRT may help your heart pump properly, and improve blood and oxygen flow in your body. CRT may decrease the backflow of blood in your heart. Having CRT may decrease your symptoms, and allow you to breathe better and have more energy.



  • Keep a current list of your medicines: Include the amounts, and when, how, and why you take them. Take the list or the pill bottles to follow-up visits. Carry your medicine list with you in case of an emergency. Throw away old medicine lists. Use vitamins, herbs, or food supplements only as directed.
  • Take your medicine as directed: Call your primary healthcare provider if you think your medicine is not working as expected. Tell him about any medicine allergies, and if you want to quit taking or change your medicine.
  • Heart medicine: This medicine is given to strengthen or regulate your heartbeat. It also may help your heart in other ways. Talk with your caregiver to find out what your heart medicine is and why you are taking it.

Ask for information about where and when to go for follow-up visits:

For continuing care, treatments, or home services, ask for more information.

  • During your follow-up visits, your caregiver will check you for signs of heart failure. Tell your caregiver about any new signs or symptoms. You may need EKG tests and an echocardiogram to check your heartbeats. You may also need chest x-rays to check the placement of the leads in your heart. You will need to see your caregiver to have your pacemaker checked. Your caregiver will check that your pacemaker is programmed right. He will also check the pacemaker battery. Ask your caregiver how often your pacemaker battery needs to be changed.

Electrical and magnetic device safety:

Some electrical devices may interfere with how your pacemaker works. These devices include cell phones, security systems, power cables, and electric monitors. Ask your caregiver how long you can be near these devices, and which devices to avoid. With a pacemaker, you will not be able to have a magnetic resonance imaging (MRI) test. An MRI uses a strong magnet that attracts the pacemaker metal, and may lead to a very serious injury. Tell your caregiver you have a pacemaker before having any procedure or surgery.

Manage your diabetes:

If you have diabetes, keep your blood sugar at the level your caregiver suggests. High levels of sugar in your blood may make your heart problem worse.

Wound care:

Follow your caregiver's instructions about how to care for your wounds after your procedure.


  • You feel dizzy or light-headed.
  • You feel more tired than normal.
  • You feel short of breath during activity.
  • You have a fever.
  • You have questions or concerns about your procedure, medicine, or care.


  • You feel like your heart is fluttering or jumping in your chest.
  • You faint (pass out).
  • You have new or increased swelling in your legs or feet.
  • Call 911 or an ambulance if you have any signs of a heart attack:
    • Discomfort in the center of your chest that feels like squeezing, pressure, fullness, or pain, that lasts for more than a few minutes or keeps returning
    • Discomfort or pain in your back, neck, jaw, stomach, or one or both of your arms
    • Feeling sick to your stomach
    • Having trouble breathing
    • A sudden cold sweat, particularly in combination with chest discomfort or trouble breathing
    • Feeling very lightheaded or dizzy, particularly in combination with chest discomfort or trouble breathing
  • Your skin around your pacemaker is red, warm, or swollen.
  • Any of your wounds are red, warm, swollen, or are draining pus.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.