Difference

Here ya go, easy look up online

by Angelie - 2010-01-07 01:01:25

Devices for Heart Failure
Controlling Arrhythmias
Heart failure often impairs the electrical system that controls the normal, steady rhythm of the heartbeat. Abnormal electrical signals that arise from damaged heart muscle may cause arrhythmias - heartbeats that are too slow (bradycardia), too fast (tachycardia) or irregular. Arrhythmias are common in heart failure patients.

The Role of Electrophysiology

Electrophysiologists create "heart maps" that pinpoint the sites that give rise to abnormal heart rhythms.
Electrophysiologists are cardiologists who have additional education and training in the diagnosis and treatment of abnormal heart rhythms. Close collaboration between these specialists and other doctors who treat patients with heart failure is important. For example, some of the drugs that are used to treat arrhythmias also decrease the heart's pumping ability. This can cause heart failure to become worse and lead to more arrhythmias. The goal of therapy is to treat abnormal heart rhythms and heart failure together.

Remarkable advances in the technology and function of implanted cardiac devices have been achieved over the past 10 years. The devices also have decreased in size. Now, they are being studied in clinical trials as treatment for patients with heart failure who are at risk of developing heart rates that are too rapid or too slow because of progressive muscle damage that can affect the heart's electrical system.


Implanted devices range in size from that of a half- dollar to the size of a small beeper.
Most of these devices can be implanted with minor surgery that may be done as outpatient procedures, or requires only a day or two in the hospital. Wires (leads) are placed in the right upper and lower chambers of the heart. A small computer, or microprocessor, is implanted under the skin, usually near the collarbone. These remarkable "built-in" computers have enormous potential to increase survival and the quality of life for the patient with heart failure. Heart failure patients may be treated with: permanent pacemakers, hemodynamic monitors, implantable defibrillators (ICDs) or resynchronization devices. Often, one or more of these features can be present in a single or 'combined' device.

Pacemakers are used to treat a heartbeat that is too slow. This may be due to heart muscle damage. Sometimes, the drugs prescribed to treat heart failure slow the heart rate. In these cases, a pacemaker may be needed to support the use of medications. Traditionally, pacemakers are attached to one or two thin wires (leads), which are placed in the right upper and lower chambers of the heart. The pacemaker continuously monitors the heart's natural rhythm and stimulates (paces) one or both chambers if the heart rate drops below a certain number of beats per minute. The patient does not feel the electrical signal that is sent from the pacemaker. Modified pacemakers also are being used to directly treat heart muscle weakness (see resynchronization therapy) in selected patients. Pacemakers have other features, as well. They can detect arrhythmias before the patient has symptoms, and lead to earlier diagnosis and treatment of heart rhythm disorders.


Electrophysiologists create "heart maps" that pinpoint the sites that give rise to abnormal heart rhythms.
Implantable Cardioverter Defibrillators (ICDs) are pacemaker-like devices that continuously monitor the heart rhythm, and deliver life-saving shocks if a dangerous heart rhythm is detected. They can significantly improve survival in certain groups of patients with heart failure who are at high risk of ventricular fibrillation (VF). VF is a deadly heart rhythm disorder that is the primary cause of sudden cardiac death (SCD). ICDs also have the ability to act as pacemakers for too-slow heart rates and can be modified to provide resynchronization therapy.

Heart failure patients who may benefit from ICDs include people who:

Have survived cardiac arrest
Have a rapid, recurrent heartbeat called sustained ventricular tachycardia, or VT
Have a history of heart muscle damage caused by a prior heart attack, and who also have non-sustained VT (a rapid heart beat that stops on its own). An electrophysiology study can determine which heart attack survivors are at risk for cardiac arrest and may need an ICD. In clinical trials, ICDs were of particular benefit for individuals with cardiomyopathy (heart muscle damage) caused by a prior heart attack.
Have an ejection fraction of 30 percent or lower. (A clinical trial of heart attack survivors with low ejection fractions found that ICD therapy saved lives compared to medications alone, even in patients with no history of VT. The benefits were so significant, the study recently was stopped so that all patients could have the option of an ICD).
Heart failure patients face a significant risk of sudden cardiac death over the course of their disease. Other clinical trials are under way to compare ICDs with conventional drug therapy, and ICDs may soon be recommended for even more patients with heart failure.


--------------------------------------------------------------------------------

Cardiac resynchronization therapy (CRT)
The U.S. Food and Drug Administration (FDA) recently approved the first of a new type of pacemaker that paces both sides of the heart simultaneously to coordinate their contractions and improve their pumping ability. Heart failure patients who have a delay in the electrical impulses to the lower chambers of the heart, a condition called bundle branch block, are potential candidates for this therapy. According to clinical trial results with selected patients, cardiac resynchronization therapy:

Increased the amount of daily activities patients could perform without experiencing the symptoms of heart failure
Extended the exercise capacity of patients with HF, as measured by the distance they could walk in 6 minutes
Improved the overall quality of life
Promoted changes in the anatomy of the heart that improved cardiac function
Reduced the number of days patients spent in the hospital, and the total number of hospitalizations
How Does CRT Work?

In the normal heart, the electrical conduction system delivers electrical impulses to the left ventricle in a highly organized pattern of contractions that pump blood out of the ventricle very efficiently. In some patients with systolic heart failure caused by dilated cardiomyopathy (an enlarged heart) this electrical coordination is lost. Uncoordinated heart muscle function leads to inefficient ejection of blood from the ventricles. CRT devices pace both the left and right ventricles simultaneously to resynchronize the muscle contraction and improve the efficiency of the weakened heart.

Clinical trials are under way to determine if resynchronization therapy improves survival in heart failure patients, and whether resynchronization devices work best if they are incorporated into pacemakers or ICDs.

Implantable Hemodynamic Monitors use pacemaker technology in which a pacing-type wire is placed in the lower right chamber (ventricle) of the heart. This wire has a sensor at the tip, which measures the pressure in both lower chambers (ventricles) of the heart. This wire has a sensor at the tip, which measures blood pressure in the ventricle. It monitors the status of heart failure patients and the effects of drug therapy. It provides information that may make it possible to intervene early to diagnose and treat worsening heart failure, before symptoms develop or hospitalization is needed. The technology may be available in future pacemaker, ICD and resynchronization devices.