After completion of this module the student should be able to:
1. List medical conditions that may result in heart failure.
2. Identify common symptoms of heart failure.
3. Describe physical findings suggestive of heart failure.
4. Discuss basic drug classes used in treating heart failure.
Heart failure results when, provided adequate venous return, the heart is unable to pump enough blood to meet the oxygen demands of the body. The underlying causes are many and often complex. Treatment generally is focused on symptomatic relief and management of contributing medical factors.
Of the many causative factors for heart failure, chronic hypertension, ischemic heart disease and myocardial infarction are the most common. Other causes or contributing factors include toxic, infectious or inflammatory myocardial diseases, diabetes, thyroid disease, anemia and valvular heart disease. The diagnosis of heart failure should be considered when there is a history of any of these conditions accompanied by fatigue, fluid retention, decreased exercise endurance, orthopnea, paroxysmal nocturnal or exertional dyspnea, nocturia or confusion.
On examination signs of volume overload such as weight gain, râles, pedal edema, jugular venous distention, hepatojuglar reflex or S3 gallop may be present. Evidence of cardiac enlargement may manifest as lateral displacement or enlargement of the apical point of maximal impulse.
Once heart failure is suspected, evaluation should include the following tests:
Electrocardiogram may demonstrate signs of ischemia, hypertrophy or arrhythmia. Evidence of ischemia should be further evaluated by exercise stress testing, if indicated.
- serum creatinine
- serum albumin
- serum electrolytes
- liver function studies
- If the patient is over the age of 65 or there a cardiac arrhythmia is noted, a TSH should also be obtained.
Echocardiogram can assist in the assessment of ventricular wall thickness and valvular function and in the estimation of ejection fraction. When an accurate ejection fraction measurement is necessary, a MUGA scan should be considered.
The patientís functional status should be documented and classified as follows:
Class I: asymptomatic
Class II: symptomatic with maximal exertion (i.e., activities that exceed ADLs)
Class III: symptomatic with minimal exertion (i.e., ADLs)
Class IV: symptomatic at rest
The most effective treatment strategies incorporate a multifaceted approach including some or all of the following modalities:
Sodium intake should be restricted to 2 to 4 grams a day. Excessive fluid intake should be avoided. Extra portions of foods rich in potassium may by advisable for patients on diuretics.
Regular exercise should be encouraged for those with stable heart failure, as it may improve functional status and alleviate symptoms. The exercise routine should be tailored to the patientís abilities and may require medical supervision in an appropriate facility.
ACE inhibitors improve both the quality of life and survival of heart failure patients and should be considered the cornerstone of heart failure medical treatment whenever possible. Use of these agents is contraindicated for patients with a history of hypersensitivity and should be used with great caution when hyperkalemia or renal insufficiency is present. Development of a dry cough is a common side effect.
Examples of ACE inhibitors: captopril, enalapril, lisinopril, fosinopril and quinapril.Diuretics are of benefit when signs of volume overload are present. The dosage should be carefully adjusted to a level that effectively removes excess fluid without causing volume depletion. This is especially true for patients concurrently taking ACE inhibitors. Diuretics should be dosed in the morning when possible to reduce the occurrence of nocturia. Serum potassium should be monitored and corrected when necessary by supplementation or increased dietary intake.
Examples of diuretics used in treatment of heart failure: hydrochlorothiazide (HCTZ), chlorthalidone, furosimide, spironolactone and metolazone. Diuretics are often incorporated in a combined formulation with ACE inhibitors, potassium sparing agents and beta blockers.Digoxin may be added to the regimen of patients in whom symptoms are not adequately controlled with ACE inhibitors and diuretics. Vasodilators such as isosorbide dinitrate or hydralazine may also be useful in these patients. Cautious introduction of a beta blockers may benefit certain patients; however, the decision to initiate this type of therapy should involve consultation with a cardiologist.
The AII receptor antagonists losartan,
valsartan and irbesartan, though currently approved only for treatment
of hypertension, seem to have similar benefits to ACE inhibitors and can
be considered for use in patients intolerant to them. Concurrent
administration with ACE inhibitors may result in added benefit.