Heart Failure: Definition, Detailed Causes And Precipitating Factors Of Cardiac Failure
This is the pathophysiological state in which the heart is not able to pump adequate amounts of blood to meet the metabolic demands of the body. If allowed to progress unchecked, cardiac failure is the most frequent complication occurring in almost all the cardiac diseases. Cardiac failure may be the result of inability of the heart to pump out a large volume of incoming blood, i.e increase in preload, or inability to pump adequate amount of blood against increased resistance, i.e increase in afterload.
Increase in preload, e.g atrial septal defect and aortic regurgitation.
Increase in afterload e.g systemic hypertension and aortic stenosis.
What are the various causes of Cardiac failure?
Reasons for Cardiac Failure
Causes of Cardiac Failure
1. Myocardial causes which reduce the contractile force of the myocardium
- Myocarditis: Infective (e.g rheumatism, typhoid, Coxsackie infection); Toxins-diphtheria, Scorpion stings, drugs like emetine, adriamycin. Nutritional causes such as beri beri, Dyscollagenosis such as Lupus erythematosus and other miscellaneous causes such as alcohol, diabetes, myxedema etc.
- Coronary artery diseases: Acute myocardial infarction, Chronic Ischemic myocardial damage,
- Cardiomyopathy both primary and secondary
- Infiltrations: Amyloidosis, hemochromatosis, leukemia, malignant deposits.
2. Structural abnormalities in the heart or great vessels which reduce the cardiac output:
- Valvular heart disease (rheumatic, syphilitic, atherosclerotic and congenital)
- Infective endocarditis,
- traumatic lesions (Injury or post-surgical)
- Congenital heart diseases.
3. Pericardial disease which leads to interference with diastolic filling of the ventricles, especially the right ventricle: Pericardial effusion, constrictive pericarditis.
- Tachycardias which lead to reduction in the diastolic interval, thereby reducing the end diastolic volume: Paroxysmal tachycardias, atrial flutter and fibrillation.
- Extreme bradycardias: Heart block in which the ventricular rate goes below 30/min.
5. Increased demand on cardiac output: Normal heart is able to cope up with even extremes of demand within physiological limits, since the reserve capacity is great. In the majority of pathological states increased demand is associated with impairment of cardiac function as well.
- severe exercise
- arteriovenous fistula
- chronic respiratory failure
- hepatic failure
6. Cor Pulmonale: Acute cor pulmonale as in pulmonary embolism or chronic cor pulmonale as in obstructive airway disease.
7. Increase afterload: Systemic arterial hypertension leads to left ventricular failure and pulmonary hypertension leads to right ventricular failure.
Multiple factors operate in almost all cases. Several conditions such as hypertension, valvular disease, or congenital heart disease may predispose the individual to heart failure. The precipitating factor may be pregnancy, anemia, fever, respiratory infection or an adverse drug reaction.
© 2013 Funom Theophilus Makama