The Pharmacologic Treatment of Heart Failure
- THIS PAGE: Causes of Heart Failure
- Page 2: Pathophysiology of Heart Failure
- Page 3: Rationale for Drug Therapy
- Page 4: Classes of Drugs Used to Treat Heart Failure
Causes of Heart Failure
Causes of Heart Failure
- Coronary artery disease
- Myocardial infarction
- Valve disease
- Congenital heart defects
- Cardiomyopathy (dilated, hypertrophic,
- Chronic hypertension
- Thyroid disease; diabetes; anemia
- Arterial-venous shunts
- Lung disease; pulmonary embolism
- Septic shock
Heart failure can be defined as the inability of the heart to provide adequate cardiac output and oxygen delivery to meet the metabolic demands of the body, or can do so only under conditions of increased cardiac preload. Heart failure can be caused by factors originating from within the heart (i.e., intrinsic disease or pathology) or from external factors that place excessive demands upon the heart, as shown in the list of causes.
The number one cause of heart failure is coronary artery disease (CAD). CAD reduces coronary blood flow and oxygen delivery to the myocardium. This leads to myocardial hypoxia and impaired function. Another common cause of heart failure is myocardial infarction, which is the final and often fatal culmination of CAD. Infarcted tissue does not contribute to the generation of mechanical activity, so overall cardiac performance is diminished. Furthermore, non-infarcted regions must compensate for the loss of function, and this extra burden can precipitate changes that lead to failure of the non-infarcted myocardium. Valvular disease and congenital defects place increased demands upon the heart that can precipitate failure. Cardiomyopathies of known origin (e.g., bacterial or viral) or idiopathic (unknown origin) can lead to failure. Myocarditis damages the heart and can lead to abnormal function. Arrhythmias, such as severe bradycardia or tachycardia, can also precipitate failure.
Acute heart failure develops rapidly and can be immediately life-threatening because the heart does not have time to undergo compensatory adaptations. Acute failure (hours/days) may result from acute infection (sepsis), reperfusion injury and stunning, acute myocardial infarction, valve chordae tendineae rupture, severe arrhythmias, etc. Acute heart failure can often be managed successfully by pharmacological or surgical interventions.
Chronic heart failure is a long-term condition (months/years) that is associated with the heart undergoing adaptive responses (e.g., dilation, hypertrophy) to a precipitating condition or pathology. These adaptive responses, however, can be deleterious in the long-term and lead to a worsening condition.