Chronic Heart Failure

What is CHF?

Chronic Heart Failure, or CHF occurs when the heart is unable to pump sufficient blood to meet the needs of the body as a result of weakened heart pumping strength. Doctors index heart strength by a parameter called the Ejection Fraction (EF). A normal EF is greater than 55%, but in CHF, it typically falls to values less than 45-50%. A failing heart is most often the result of damage to the heart muscle from injuries such as heart attack, untreated coronary artery disease, or persistent high blood pressure. It can also be a genetically inherited condition or can occur as a result of an infection.

How common is CHF?

Heart failure is a disease of epidemic proportions that affects more than 25 million people across the world. One out of 10 people over the age of 65 will suffer from heart failure (American Heart Association; www.americanheart.org).

What are the symptoms of CHF?

Common symptoms of heart failure include shortness of breath, fatigue, weakness, persistent coughing and difficulty performing everyday tasks such as grocery shopping or climbing stairs. Another sign of heart failure is the accumulation of fluids in the legs, feet, abdomen, lower back and lungs.

How is CHF treated?

Heart failure is a chronic disease requiring lifelong management. Some forms of heart failure are treated with drugs or with implanted devices such as pacemakers and implantable cardiac defibrillators. However, these treatments are not suitable for all patients and do not always result in an improvement of symptoms. The Optimizer Smart System with CCM technology has been developed to help ease the symptoms in most patients where other treatments are either not applicable or have proven to be minimally effective.

Heart failure treatment

Treatment of heart failure depends on its cause. The overall goals of treatment are to correct underlying pathology, to relieve symptoms, to prevent a worsening of the condition, to reduce the frequency of hospitalizations, and to prolong life.

All patients with CHF receive medical treatment in the form of diuretics (“water” pills), angiotensin-converting enzyme inhibitors, beta-blockers, or aldosterone inhibitors (all drugs that block the body’s neurohormonal system), unless they suffer from side-effects as a result of drug treatment. In most patients with CHF, an ICD device is also recommended, to treat potentially life-threatening abnormally fast heart rhythms. Patients with prolonged QRS duration and dyssynchronous contractions (which occur in about 30% of cases) receive additional Cardiac Resynchronization Therapy (CRT), a special type of pacemaker, on top of medications and ICD device implant. Most patients with heart failure however, have normal QRS duration and do not benefit from CRT treatment. For these patients, representing approximately 70% of those suffering from CHF, there was no device-based treatment available until now. The Optimizer™ System by Impulse Dynamics offers, for the first time, a solution for patients with moderate to severe heart failure and normal QRS duration.

Terminology

Ejection Fraction (EF)

Is the amount of blood pumped out of the heart’s main pumping chamber (i.e., the left ventricle) with each heartbeat, expressed as a percent of the volume of blood inside this chamber at the start of the beat. The heart normally ejects about 55-70% of the blood in its ventricle with each contraction. People with CHF and weak heart muscle will typically have an EF less than 45-50%.

QRS Complex

The sharp peak on an electrocardiogram (ECG, a recording of the heart’s electrical activity) that corresponds to the electrical activity generated when the muscles of the ventricles become activated and start contracting. Normally, the duration of the QRS complex is less than 120 milliseconds, indicating that the entire heart muscle becomes activated within 120 milliseconds. In many patients with heart failure, the QRS complex becomes abnormally long; indicating that it takes much longer to activate all of the heart’s muscles and the contraction becomes dyssynchronous. In such cases, a treatment called “cardiac resynchronization therapy” (CRT, described below) may be indicated.

Cardiac Resynchronization Therapy (CRT)

Also referred to as biventricular pacing, is a form of therapy for CHF in which a specialized pacemaker is used to re-coordinate the action of the right and left ventricles. CRT is indicated for CHF patients that suffer from cardiac dyssynchrony characterized by a prolonged QRS duration.

Implantable Cardioverter Defibrillator (ICD)

Devices that monitor the heart for potentially dangerous types of heart rhythms, such as ventricular fibrillation (when the heat muscles contract in a completely chaotic manner so that no blood is pumped) or tachycardia (when the heart beats very fast). When an ICD detects such a rhythm, it delivers electrical shocks to try and restore normal contractions. ICDs are important for prolonging life in some patients with heart failure, but do not treat heart failure as they do not help to improve a patient’s quality of life or exercise tolerance.

Minnesota Living with Heart Failure Questionnaire (MLWHFQ)

A heart failure specific questionnaire filled out by patients that includes 21 questions selected to be representative of the ways heart failure can affect the key physical, emotional, social and mental dimensions of quality of life. The patients grade each question on a scale of 1 to 6; 1 for good quality of life, and 6 for poor quality of life. The grades are used to create a global index of quality of life. The MLWHFQ is used to quantify a patient’s quality of life and to track changes in quality of life in response to treatment. A lower score on the MLWHFQ is associated with an improved quality of life.