Overview of heart failure
Congestive heart failure, also known as heart failure (HF) is a condition which results from any structural or functional heart disorder that impairs the heart’s ability to pump sufficient blood through the body. Although HF can occur at any age, it is more common among the elderly people as age-related changes tend to reduce the functional efficiency of the heart. Further, this group of the population is more likely to have disorders that damage the heart muscle.
Heart failure constitutes a major public health problem in the Western world. This condition affects nearly five million Americans with an incidence nearly 10 per 1000 persons among individuals above 65 years of age.1 Five-year survival rates of HF patients had been estimated to be only 45% in women and 59% in men.2
The diagnosis of HF is complex. Early diagnosis of HF is essential in order to adequately control the underlying disease or causes. Evaluation of symptomatic patients with suspected HF focuses on confirming the diagnosis, determining the cause, identifying concomitant illnesses, establishing the severity and directing the therapy. The goals of the HF therapy include targets on improving the survival by slowing down the disease progression, alleviating the symptoms and minimizing the risk factors. Lifestyle modifications help in controlling the symptoms and improving the quality of life.
Classification of heart failure
There are many different ways to classify HF. Each depends upon the following criteria:
- The side of the affected heart—left HF or right HF.
- The type of the abnormality—either due to contraction (systolic dysfunction) or relaxation (diastolic dysfunction) of the heart.
- The cause of the failure—either due to low cardiac output or high systemic vascular resistance (low- vs. high-output failure).
- The extent of functional impairment caused by the abnormality.
The New York Heart Association (NYHA) Functional Classification which documents severity of symptoms is widely used in the clinical practice and in clinical studies to quantify the clinical assessment of HF and to assess response to the treatment.3 The NYHA functional classifications based on physical activities are:
- Class I: No limitation in any activities.
- Class II: Mild limitation of activity.
- Class III: Marked limitation of any activity.
- Class IV: Symptoms of HF occur even at rest.
Etiology and Pathophysiology of heart failure ( Causes of heart failure)
The most common causes of HF are listed below:
- Coronary artery disease (CAD)—accounts for nearly 70% of all HF cases.4
- Cardiomyopathy (diseases of the heart muscle).
- Myocarditis (inflammation of the heart muscle).
- High blood pressure.
- Heart valve disorders.
- Abnormal heart rhythms.
- Congenital heart disease.
- Exposure to cardiotoxic drugs such as cocaine.
- Excess alcohol consumption.
- Noncardiac causes such as diabetes mellitus, thyroid disorders and chronic severe anemia.
Although the heart is capable to adapt to short-term changes in preload or afterload, sudden or sustained changes in preload (as in acute mitral regurgitation), afterload (as in severe uncontrolled hypertension) or increased demand (because of severe anemia or hyperthyroidism) may lead to progressive failure of myocardial function. Asymptomatic dysfunction progresses steadily to overt HF.
Heart failure due to systolic dysfunction usually develops when the heart cannot contract normally. As a consequence, the amount of blood pumped to the lungs and to the body is reduced, leading to enlargement of the heart, particularly the left ventricle. Heart failure due to diastolic dysfunction develops because of stiffening and thickening of the heart’s walls, leading to incomplete filling of the heart with blood during relaxation of the heart. Consequently, blood backs up in the left atrium and pulmonary (lung) blood vessels and causes pulmonary congestion.
Clinical Features (Symptoms of heart failure)
Symptoms of HF are largely determined by side of the heart (left or right), which fails. The clinical features of HF are mainly due to an accumulation of fluid in the lungs and the body. These symptoms are based on the affected side of the heart, which include the following:
Predominant left-sided HF:
- Dyspnea (shortness of breath at rest or with activities).
- Orthopnea (shortness of breath when lying down flat).
- Paroxysmal nocturnal dyspnea (shortness of breath at night causing sudden awakenings).
- Chronic cough.
Predominant right-sided HF:
- Pedal edema (fluid retention in the legs).
- Ascites (excess fluid in peritoneal cavity).
- Congestive hepatomegaly (liver enlargement).
- Anasarca (generalized edema).
- Other gastrointestinal symptoms caused by congestion of the liver and gastrointestinal venous circulation include abdominal bloating, nausea and constipation.
Heart failure can be identified with the presence of signs such as jugular venous distention, abdominal jugular reflux, pulmonary rales, displacement of cardiac apical pulsation or presence of a gallop heart sound (S3).
Diagnosis of heart failure
According to the European Society of Cardiology guidelines, in addition to typical symptoms suggestive of the diagnosis of HF, objective evidence of cardiac dysfunction has to be present to establish the presence of HF.5 The initial evaluation should include a complete history and physical examination, a chest radiograph and an electrocardiogram (ECG).
The typical radiographic findings include cardiomegaly (enlarged heart), pulmonary edema and pleural effusion. No specific ECG feature is indicative of HF, but atrial and ventricular arrhythmias are common findings. The presence of HF can be confirmed by an echocardiogram. The Doppler echocardiogram can identify systolic and diastolic dysfunction, presence of valvular stenosis, cardiomyopathy or pericardial disease. Radionuclide angiography may be performed, when the echocardiogram is ambiguous despite a high clinical suspicion of HF. Magnetic resonance imaging (MRI) and computed tomography (CT) can measure the ejection fraction and assess the regional wall motion.
The routine blood investigations include a complete blood count, liver function test, serum electrolyte, kidney function test, lipid profile, thyroid profile and B-type natriuretic peptide (BNP) which is found to be elevated in HF. Patients with CAD, hypertension, diabetes mellitus, exposure to cardiotoxic drugs or alcohol abuse are at high-risk for HF and they may benefit from routine screening.6
Treatment of heart failure
The management of HF depends on its cause and clinical course, therefore an individualized approach to the treatment is mandatory. Diuretics and angiotensin converting enzyme (ACE) inhibitors, when combined with nonpharmacological measures, remain the basis of treatment in patients with HF.
The pharmacologic treatment tackles four specific management goals:
- Optimization of the treatment of etiologic conditions.
- Treatment of fluid retention symptoms.
- Prevention of disease progression.
- Delay in mortality.
The following pharmacological agents are used:
For symptomatic improvement:
- Diuretics—furosemide, thiazide and spironolactone
- ACE inhibitors—enalapril, lisinopril and perindopril
- Angiotensin receptor blockers (ARBs)—losartan and candesartan
- Positive inotropes—digoxin
For improvement in survival
- ACE inhibitors
- Beta-blockers—carvedilol, metoprolol and atenolol
- Vasodilators—oral nitrates in combination with hydralazine
Diuretic therapy is indicated for relief of congestive symptoms. The ACE inhibitors, when added to diuretics, improve the symptoms, exercise tolerance and reduce hospital admission rates in chronic HF. The primary action of beta-blockers is to counteract the unfavorable effects of the sympathetic nervous system that are activated during HF. The beneficial effects of beta-blockers include improvement in the heart remodeling and ejection fraction, the rate of hospitalization, survival, quality of life and the incidence of sudden death.7
The ARBs should be used only in patients who cannot tolerate ACE inhibitors because of severe cough or angioedema (rapid swelling of the skin, mucosa and submucosal tissues). In patients who remain symptomatic despite diuretic and beta-blocker therapy, treatment with the vasodilator combination of hydralazine and isosorbide dinitrate may be an alternative.7 Once used as first-line therapy, digoxin is now reserved for the control of ventricular rhythm in patients with atrial fibrillation or where adequate control is not achieved with an ACE inhibitor, beta-blocker or a diuretic.
Various nonpharmacological measures to improve symptoms and prognosis of HF include the following:8
- A regularly scheduled exercise program, for selected patients.
- Weight reduction and weight monitoring.
- Sodium restriction.
- Fluid restriction, limited to 1.5 L daily.
- Avoidance of nonsteroidal antiinflammatory drugs (NSAIDs).
- Abstain from or limit alcohol consumption.
Revascularization and Surgical Therapy
As CAD is the primary etiology in two-thirds of all cases of HF, practice guidelines and recent studies recommend coronary revascularization for patients with HF and CAD.9 Patients with severe CAD and symptomatic left ventricular systolic dysfunction had been observed to have poor outcomes, when treated medically, despite the advances in medical therapy over the past decade.
Revascularization either by coronary artery bypass graft surgery or by percutaneous coronary intervention may improve the long-term outcomes in patients with left ventricular dysfunction and myocardial ischemia, and reduces the risk of sudden death.10
1.Jessup M, Brozena S. Heart failure. N Engl J Med. 2003; 348: 2007–2018.
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3.Criteria Committee of the New York Heart Association. Nomenclature and criteria for diagnosis of diseases of the heart and great vessels. 9th ed. Boston: Little, Brown, 1994.
4.Gheorghiade M, Bonow RO. Chronic heart failure in the United States: A manifestation of coronary artery disease. Circulation. 1998; 97: 282–289.
5.Remme WJ, Swedberg K. Guidelines for the diagnosis and treatment of chronic heart failure. Task Force for the diagnosis and treatment of chronic heart failure, European Society of Cardiology. Eur. Heart J. 2001; 22: 1527–1560.
6.Hunt SA, Baker DW, Chin MH, Cinquegrani MP, Feldman AM, Francis GS, et al. ACC/AHA guidelines for the evaluation and management of chronic heart failure in the adult. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2001; 38: 2101–2113.
7.Jessup M, Brozena S. Heart failure. N Engl J Med. 2003; 348(20): 2007–2018.
8.Smith A, Aylward P, Campbell T, et al. Therapeutic Guidelines: Cardiovascular, 4th edition. North Melbourne: Therapeutic Guidelines; 2003. ISSN 1327–9513.
9.Tsuyuki RT, Shrive FM, Galbraith PD, Knudtson ML, Graham MM; APPROACH Investigators. Revascularization in patients with heart failure. CMAJ. 2006; 175(4): 361-365.
10.Baumgartner WA. What's new in cardiac surgery? J Am Coll Surg. 2001; 192: 345–355.