“We continue to be encouraged by the early clinical results demonstrated by the Parachute® implant. In all of our previous studies we have seen similar improvements in treated heart failure patients.”Thomas Engels, Vice President of Clinical Affairs of CardioKinetix Inc.
In the United States, more than six million people are living with heart failure (HF), and more than 600,000 new HF patients are diagnosed each year. Coronary artery disease, a partial blockage of the blood vessels in the heart muscle, causes most cases of HF. During a heart attack, a complete blockage of blood supply to a part of the heart muscle destroys tissue and impairs the heart’s ability to provide sufficient blood flow to the body.
Other contributing factors to HF include: cigarette smoking, high blood pressure (hypertension), obesity, diabetes, alcohol abuse, HIV infection, and the effects of certain chemotherapeutic agents used to treat cancer.
HF describes a wide array of symptoms, and varying levels of severity. HF is classified according to the side of the heart involved, right or left ventricle, and whether the abnormality is related to the heart’s inability to pump, or a high pressure in the vascular system that requires abnormally high cardiac output. Class III patients are unable to perform most normal daily activities, and are comfortable (not out of breath), only when at rest. Class IV patients are unable to perform any activity, and have symptoms even when at rest.
HF patients with left-sided failure have left ventricle abnormalities that are most frequently caused by previous heart attacks, and present with symptoms including fatigue, and extreme breathlessness with exertion (dyspnea). Some patients experience an increase in breathlessness when lying down (orthopnea), and are most comfortable sleeping with pillows, in a semi-sitting position. Patients may also have sudden attacks of severe breathlessness during sleep (paroxysmal nocturnal dyspnea), similar to an asthma attack.
Right-sided HF patients commonly have excess fluid accumulation build up in the body, causing swelling under the skin that affects lower extremities. Frequent night time urination is common as fluids are returned to the bloodstream during sleep. In severe cases swelling may affect the liver and cause jaundice (a yellow hue to the skin).
Physicians use a variety of tests to confirm heart failure (HF). Diagnostic testing is recommended in the presence of symptoms, including: shortness of breath, fatigue, swelling in the feet or ankles, and increased heart or breathing rate.
Patients are often first evaluated using a chest X-ray; the physician looks for an enlarged heart, or fluid in the lungs. In patients who have a previous history of a heart attack, angiography may be used to look for any new blockages in the coronary arteries. Patients may also receive an electrocardiogram (EKG), a quick painless test that measures electrical activity in the heart. The physician will read the EKG tracing to look for abnormal rhythms or out-of-sync heart beats.
One of the most common tools to confirm HF is an Echocardiogram, a non-invasive ultrasound procedure that measures the size of the heart’s chambers in real time. Physicians use precise measurement of ventricles during the heart beat to determine the precise volume of blood flow. Doppler ultrasound imaging allows physicians to visualize, in real time, the flow of blood entering and leaving the ventricles in the heart.
HF patients are classified, based upon their symptoms and the resulting limitations on their activities. Class 1 patients have no symptoms (although there is an underlying finding of heart failure). Class II patients have mild symptoms, some limitations on normal activity, but are comfortable at rest. Class III patients are very limited in their activities, and are only comfortable at rest. Class IV patients experience severe limitation of activity, and have symptoms even while at rest.
Most patients living with heart disease respond to treatments that help reduce fatigue, shortness of breath, and other symptoms. Medical professionals often use a multidisciplinary approach to HF patients that includes treatment, rehabilitation, and lifestyle counseling. Patients may be asked to work with a dietician, physical therapist, cardiologist, and other specialists.
Clinical treatment for CHF often begins with drug therapy. Prescription medications commonly used to treat CHF include:
Known as ACE Inhibitors, are often the first choice in treatment, this class of drugs has been proven clinically to slow the progression of heart disease. The drugs act on the blood vessels, causing them to expand, which lowers blood pressure and reduces the amount of work the heart must do to maintain blood flow to the body.
Known as ‘water pills,’ help the body to remove excess fluid from the bloodstream, the drugs act on the kidneys, and helps them to convert more water and sodium in the blood to urine. As there is less fluid in the bloodstream to pump, the workload on the heart is reduced.
Used to increase the force of contractions with each beat of the heart, the drugs act directly on the heart muscle tissue, and the stronger contractions force more blood flow through the heart, which reduces CHF symptoms.
Used to help the stressed heart slow down its rhythm, the receptors in muscle tissue cells are dulled, lowering heart rate and blood pressure, which improves symptoms.
Mechanical devices are used to treat HF, either to ‘assist’ with ventricle pumping, or as ‘resynchronization’ aids to ensure the heart beats as efficiently as possible.
Approximately 25% of patients with advanced (ischemic) HF have ventricular dysynchrony resulting in a reduction of cardiac output. Patients with advanced HF and ventricular dysynchrony are most likely to benefit from the simultaneous pacing of both right and left ventricles. Some CRT devices also provide defibrillation to protect against sudden cardiac death resulting from arrhythmias. In addition, some Implantable Cardiac Defibrillators (ICDs) have a CRT “capacity” and can be used in such patients to provide HF therapy combined with prophylactic treatment of ventricular fibrillation or sudden death.
The LVAD improves cardiac output by pumping blood in parallel with the weakened heart chamber. The new portable LVAD units enable some patients to resume some activities after discharge from the hospital. Recently, LVAD’s were approved for so called “destination therapy” as an alternative to heart transplantation in those patients not eligible for a heart transplant procedure.
Surgical intervention is also used to treat HF, including procedures to repair damaged portions of the heart, up to and including heart transplant. Patients for whom a heart attack is the cause of HF, may need coronary artery bypass surgery, to restore blood flow to a damaged portion of the heart muscle. Angioplasty may be used to open clogged blood vessels in the heart as a means of restoring blood supply to the heart.
In the illustration from the publication by M. Jessup et al. NEJM, 2003:348,20, the Parachute is shown where in the HF cycle it may benefit a patient.