Introduction

Heart failure is the final common pathway for many cardiovascular diseases whose natural history results in symptomatic or asymptomatic left ventricular dysfunction. The cardinal manifestations of heart failure are dyspnea, fatigue and fluid retention. These symptoms can impair the functional capacity and quality of life of the affected individuals. In the US, approximately 2,50,000 patients die as a direct or indirect consequence of heart failure each year, and the number of deaths due to heart failure has increased 6-fold during the past 40 years. The risk of death is 5-10% annually in patients with mild symptoms and increases to as high as 30-40% annually in patients with advanced disease.

Prevalence

The prevalence of heart failure increases with age. Ageing of the population and the prolonged survival of patients with a variety of cardiovascular diseases that culminate in ventricular dysfunction ensure that the magnitude of the heart failure problem will substantially worsen in the next decade. Approximately 1.5-2% of the US population has heart failure and the prevalence increases to 6-10% in patients aged above 65 years.

Main causes of heart failure

• Coronary artery disease
• Hypertension
• Valvular heart disease (especially aortic and mitral disease)
• Cardiomyopathy

Compensatory changes in heart failure

Classification of heart failure

The functional status of patients with heart failure is most commonly assessed using the
New York Heart Association (NYHA) classification. Patients can be assigned to 1 of 4 functional classes depending on the degree of effort needed to elicit symptoms. This classification is widely used but lacks sensitivity to detect small but important changes in clinical status.

Types of heart failure

Congestive heart failure can be broadly subdivided into two distinct forms:
1. Diastolic dysfunction or diastolic heart failure
2. Systolic dysfunction or systolic heart failure

A patient with systolic heart failure commonly has a left ventricular ejection fraction less than 30%, while in diastolic heart failure, there is impaired left ventricular relaxation or filling (diastolic dysfunction), with normal or even supernormal contraction (systolic function). Thus unlike diastolic dysfunction, the ejection fraction is normal in systolic dysfunction.

Factors aggravating heart failure

• Myocardial ischemia or infarct
• Dietary sodium excess
• Excess fluid intake
• Medication noncompliance
• Arrhythmias
• Intercurrent illness (e.g. infection)
• Conditions associated with increased metabolic demand
  (e.g. pregnancy, anaemia, thyrotoxicosis, excessive physical activity)
• Administration of drug with
  - negative inotropic properties
  - fluid retaining properties (e.g. NSAIDs, corticosteroids)
• Alcohol