It is important to recognise underlying causes and precipitating factors of heart failure for its appropriate management. That would also help in prevention and treatment of heart failure.The causes could be broadly classified as those due to myocardial damage or volume overload or pressure overload or arrhythmias.
Myocardial Damage
Coronary artery disease (myocardial ischemia or infarction), myocarditis, cardiomyopathies could lead to myocardial dysfunction.
Volume Overload Conditions
Valvular diseases (e.g. aortic regurgitation, mitral regurgitation) and congenital heart diseases (e.g. ventricular septal defect, patent ductus arteriosus)
Pressure Overload Conditions
Hypertension, aortic stenosis, coarctation of aorta impose pressure overload on the heart.
Precipitating Causes of Heart Failure
In majority of the cases one is often able to identify a precipitating cause of heart failure.
Arrhythmias
Cardiac arrhythmias are common in patients with various types of heart diseases and may precipitate or worsen heart failure through several mechanisms:
a) Tachyarrhythmias reduce ventricular filling, increase myocardial oxygen demand and in patients with coronary artery disease aggravate myocardial ischemia. This results in both systolic and diastolic dysfunction. If persistent it may cause a reversible cardiomyopathy(tachyarrhythmias induced cardiomyopathy).
b) Marked bradycardia in patients with underlying heart disease depresses cardiac output.
c) Atrioventricular dissociation results in loss of atrial boost leading to impaired ventricular filling, lower cardiac output and raised atrial pressure.
d) Abnormal intraventricular conduction impairs myocardial performance due to asynchronous ventricular contraction.
Myocardial Ischemia
In patients with coronary artery disease an acute coronary syndrome event can precipitate heart failure. Mitral regurgitation occurring as a result of papillary muscle ischemia contributes to heart failure and may even produce acute pulmonary edema.
Systemic Infection
Serious infections increase total body metabolism and thus impose hemodynamic burden on the heart. Increased heart rate associated with infections is an additional burden. Circulating inflammatory cytokines are known to impair myocardial function and thus precipitate heart failure. The infectious process may also have an element of myocarditis.
Pulmonary Embolism
Patients with heart failure are at a higher risk of developing deep vein thrombosis and pulmonary embolism. Pulmonary thrombo-embolism exerts hemodynamic stress on the right side of the heart.
Other Factors
Stress in any form be it physical, emotional or environmental, development of unrelated illness,exposure to cardiac depressants drugs (cancer chemotherapy, negative inotropic drugs), cardiac toxins (alcohol, cocaine), pregnancy, anemia, thyroid disorders are some of the common conditions that may precipitate heart failure.
Non-compliance
Inappropriate reduction of therapy or noncompliance of therapy is an important cause to be kept in mind when encountered with worsening heart failure.One should make a diligent and systematic search for these precipitating factors and they should be treated adequately and appropriate steps should be taken to avoid recurrences. Identifying precipitating factors generally denotes better prognosis for the patients.
Myocardial Damage
Coronary artery disease (myocardial ischemia or infarction), myocarditis, cardiomyopathies could lead to myocardial dysfunction.
Volume Overload Conditions
Valvular diseases (e.g. aortic regurgitation, mitral regurgitation) and congenital heart diseases (e.g. ventricular septal defect, patent ductus arteriosus)
Pressure Overload Conditions
Hypertension, aortic stenosis, coarctation of aorta impose pressure overload on the heart.
Precipitating Causes of Heart Failure
In majority of the cases one is often able to identify a precipitating cause of heart failure.
Arrhythmias
Cardiac arrhythmias are common in patients with various types of heart diseases and may precipitate or worsen heart failure through several mechanisms:
a) Tachyarrhythmias reduce ventricular filling, increase myocardial oxygen demand and in patients with coronary artery disease aggravate myocardial ischemia. This results in both systolic and diastolic dysfunction. If persistent it may cause a reversible cardiomyopathy(tachyarrhythmias induced cardiomyopathy).
b) Marked bradycardia in patients with underlying heart disease depresses cardiac output.
c) Atrioventricular dissociation results in loss of atrial boost leading to impaired ventricular filling, lower cardiac output and raised atrial pressure.
d) Abnormal intraventricular conduction impairs myocardial performance due to asynchronous ventricular contraction.
Myocardial Ischemia
In patients with coronary artery disease an acute coronary syndrome event can precipitate heart failure. Mitral regurgitation occurring as a result of papillary muscle ischemia contributes to heart failure and may even produce acute pulmonary edema.
Systemic Infection
Serious infections increase total body metabolism and thus impose hemodynamic burden on the heart. Increased heart rate associated with infections is an additional burden. Circulating inflammatory cytokines are known to impair myocardial function and thus precipitate heart failure. The infectious process may also have an element of myocarditis.
Pulmonary Embolism
Patients with heart failure are at a higher risk of developing deep vein thrombosis and pulmonary embolism. Pulmonary thrombo-embolism exerts hemodynamic stress on the right side of the heart.
Other Factors
Stress in any form be it physical, emotional or environmental, development of unrelated illness,exposure to cardiac depressants drugs (cancer chemotherapy, negative inotropic drugs), cardiac toxins (alcohol, cocaine), pregnancy, anemia, thyroid disorders are some of the common conditions that may precipitate heart failure.
Non-compliance
Inappropriate reduction of therapy or noncompliance of therapy is an important cause to be kept in mind when encountered with worsening heart failure.One should make a diligent and systematic search for these precipitating factors and they should be treated adequately and appropriate steps should be taken to avoid recurrences. Identifying precipitating factors generally denotes better prognosis for the patients.
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