By: AMFS Cardiology Physician #E19616
Congestive heart failure can be simply described as the inability of the heart to meet the metabolic demands of the body. The heart functions as a pump to deliver oxygen and nutrients to the tissues. Failure of the pump to deliver nutrition to the tissues stimulates a number of compensatory responses in an effort to improve tissue perfusion. These responses result in the clinical symptoms and signs associated with the heart failure syndromes—shortness of breath, rapid heartbeat, and fluid retention.
Many conditions can be associated with heart failure. Sometimes the metabolic needs of the body are increased to such an extent that the heart cannot compensate.
Patients with severe anemia or thyroid disease may develop signs of heart failure without any structural cardiac abnormalities. Generally however we categorize heart failure as disorders of cardiac emptying or cardiac filling. The former are often called systolic heart failure or heart failure with reduced ejection fraction (HFREF). The most common cause of systolic heart failure in Western society is myocardial infarction (heart attack). Other less common causes include heart valve disorders and primary disease of the heart muscle (often referred to as cardiomyopathy). Viruses and toxins such as alcohol or certain drugs can damage heart muscle and cause heart failure.
Recent studies have suggested that disorders of cardiac filling may be as common and as dangerous as HFNEF. This condition is often termed diastolic heart failure or heart failure with preserved ejection fraction (HFPEF). Ageing, female sex and high blood pressure contribute to increased stiffness and thickening of the heart muscle so that higher pressures are required to fill the heart between beats (diastole). When that high pressure is transmitted to the lungs it causes fluid to accumulate and the patient to develop shortness of breath. The diagnosis of HFPEF is often difficult and the treatment much less well-defined than HFREF. Many of the agents shown to benefit patients with weak hearts have been shown to be ineffective in the treatment of diastolic heart failure.
Physical Examination and Symptoms
Patients generally present to their doctor with symptoms and signs of reduced heart function or fluid retention. They often note fatigue and shortness of breath, particularly with activity. Chest pain may be associated with coronary disease (cholesterol buildup in the arteries) and myocardial infarction. The exam often discloses signs of fluid retention in the lungs and edema in the feet. The heart rhythm may be rapid or irregular and signs of valvular disease may be apparent when examining the heart.
Laboratory studies may show anemia, thyroid abnormality, or enzyme evidence of cardiac injury. A protein produced by the heart when the intra-cardiac pressure is increased—brain natriuretic peptide, is a sensitive indicator of cardiac dysfunction.
The ECG is often abnormal and may show abnormalities of heart rhythm, thickened heart muscle (hypertrophy) or evidence of recent or distant heart attack. Chest x-rays allow the physician to estimate cardiac size and often show fluid in or around the lungs. Cardiac CT and MRI are increasingly utilized to assess heart function and structure and sometimes to look at the coronary arteries. Stress testing may help identify coronary disease.
The most valuable test in the evaluation of heart failure is the echocardiogram. This noninvasive test shows heart structure and function, the valves and their function and allows the cardiologist to estimate pressure in the heart and the lungs. Every patient in whom heart failure is suspected should undergo echocardiography for evaluation.
Cardiac catheterization and angiography are commonly performed in patients when coronary disease cannot be excluded by noninvasive evaluation. Cholesterol blocking the arteries (the cause of myocardial infarction or heart attack) is one of the few reversible causes of reduced heart function and should always be excluded in patients with abnormal heart muscle function.
The treatment of systolic heart failure includes dietary salt restriction and generally physical exercise. Diuretics reduce fluid retention and improve shortness of breath and edema (leg swelling). They do not improve outcome. Three classes of drugs have been shown to improve heart function and outcome in patients with systolic heart failure: ACE inhibitors/ARBs, beta blockers and aldosterone antagonists. These drugs should generally be part of the standard treatment plan.
The treatment of diastolic heart failure (or HFPEF) is much less well defined. Clinicians generally focus on diuretic therapy to reduce lung fluid and blood pressure lowering drugs to make the heart less thick. The drugs that work so well for systolic heart failure have not been shown to positively affect diastolic heart failure and the proper treatment remains unknown.
There has been great interest in device therapy for heart failure. Defibrillators reduce the likelihood of sudden death in patients with abnormal heart function and recent trials have suggested they may be useful in patients with less severe heart failure than implanted originally. Resynchronization (generally performed concurrently with defibrillator implantation) improves the coordination of heart contraction and may improve heart muscle function. Ventricular assist devices support patients with very severe heart failure and there is recent evidence these devices sometimes allow the heart to recover function. Finally heart transplantation is a very successful strategy to cure heart failure and the long-term success of transplantation has improved greatly in the last fifteen years. This treatment is severely limited by the low number of donor hearts and the large number of patients listed for transplant. A significant number of patients with heart failure die waiting for a heart.
Conclusions and Considerations
Congestive heart failure is an enormous medical problem. Admissions for CHF are the most common DRG in the Medicare system and present an enormous public health burden. As the population ages the number of patients with heart failure continues to increase. Better strategies for prevention and treatment are urgently needed, particularly for the burgeoning number of the elderly with diastolic heart failure.
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