Congestive Cardiac failure is a condition associated with heart disorders leading to impairment of the heart to supply sufficient blood to meet the body requirements. Cardiac Failure may be associated with the failure of the right or left ventricle or both. Cardiac failure causes the blood to move through the heart and body at a slower rate, leading to increased pressure in the heart. As a result, the heart is unable to pump enough oxygen and nutrients to meet the body’s requirements. The heart chambers thus respond by stretching in order to hold more blood to pump through the body or by becoming stiffer and thickened. Such a mechanism helps to keep the blood moving for a short while, but the heart muscle walls tend to weaken with time and they are unable to pump with enough strength.
The direct result of the reduced contractility of the cardiac muscles especially those of the ventricles causes a decrease in the cardiac output and increase in the blood volume of the heart. This causes the kidneys to often respond by causing the body to retain fluid (water) and sodium, as the systemic blood pressure and the renal blood flow both are reduced. This results in the building up of fluid in the arms, legs, ankles, feet, lungs, or other organs causing edema which makes the body congested, hence the name Congestive cardiac failure.
The term congestive heart failure is used for the chronic form of heart failure in which the patient has evidence of congestion of peripheral circulation and of lungs; CHF is the end result of various forms of serious heart diseases.
Table of Contents
Etiology
There are many causes of congestive heart failure including:
- Coronary artery disease leads to heart attacks and heart muscle weakness.
- Primary heart muscle weakness from viral infections or toxins such as prolonged alcohol exposure.
- Heart valve disease causes heart muscle weakness due to too much leaking of blood or heart muscle stiffness from a blocked valve, and
- Hypertension.
Rarer causes of heart failure include:
- Viral myocarditis (an infection of the heart muscle).
- Infiltrations of the muscle such as amyloidosis.
- HIV cardiomyopathy (caused by Human Immunodeficiency Virus).
- Connective tissue diseases such as Systemic lupus erythematosus.
- Abuse of drugs such as alcohol.
- Pharmaceutical drugs such as chemotherapeutic agents.
- Arrhythmias.
Major causes include Ischemic Heart, Hypertension, Cardiomyopathy.
Pathogenesis Congestive Cardiac failure
Heart failure may be caused by one of the following factors either singly or in combination.
Intrinsic Pump Failure: The most common and most important cause of heart failure is the weakening of the ventricular muscle due to disease so that the heart fails to act as an efficient pump. The various diseases which may culminate in pump failure by these mechanisms are as under:
- Ischaemic heart disease,
- Myocarditis,
- Cardiomyopathies,
- Metabolic disorders like beriberi,
- Disorders of the rhythm e.g. atrial fibrillation and flutter.
Increased workload on the heart: Increased mechanical load on the heart results in increased myocardial demand resulting in myocardial failure. Increased load on the heart may be in the form of pressure load or volume load.
(a) Increased pressure load may occur in the following states:
- Systemic and pulmonary arterial hypertension.
- Valvular disease e.g. mitral stenosis, aortic stenosis, pulmonary stenosis.
- Chronic lung diseases.
(b) Increased volume load occurs when a ventricle is required to eject more than the normal volume of the blood resulting in cardiac failure. This is seen in the following conditions:
- Valvular insufficiency
- Severe anemia
- Thyrotoxicosis
- Arteriovenous shunts
- Hypoxia due to lung diseases.
Impaired filling of cardiac chambers: Decreased cardiac output and cardiac failure may result from extracardiac causes or defects in filling of the heart in pericarditis.
Types of Heart Failure
Congestive heart failure (CHF) is generally classified as systolic or diastolic heart failure and becomes progressively more common with increasing age. In addition, patients with risk factors for heart disease are more likely to develop congestive heart failure.
Systolic heart failure:
This condition occurs when the pumping action of the heart is reduced or weakened. A common clinical measurement is ejection fraction (EF). The ejection fraction is a calculation of how much blood is ejected out of the left ventricle (stroke volume) divided by the maximum volume remaining in the left ventricle at the end of diastole, or when the heart is relaxed after filling with blood. A normal ejection fraction is greater than 55%. Systolic heart failure is diagnosed when the ejection fraction has significantly decreased below the threshold of 55%.
Diastolic heart failure:
This condition occurs when the heart can contract normally but is stiff, or less compliant when it is relaxing and filling with blood. The heart is unable to fill with blood properly, which produces back up into the lungs and heart failure symptoms. Diastolic heart failure is more common in patients older than 75 years of age, especially in patients with high blood pressure, and it is also more common in women. In diastolic heart failure, the ejection fraction is normal or increased.
Acute heart failure:
It is the sudden and rapid development of failure following massive myocardial infarction, valve rupture myocarditis, etc. The sudden reduction in cardiac output, hypotension without edema is prominent features.
Chronic heart failure:
It develops slowly with the gradual reduction in cardiac output. It is commonly seen in slowly progressive valvular heart disease, systemic arterial hypertension, chronic obstructive pulmonary diseases, etc. Blood pressure is well maintained but is associated with peripheral edema.
Clinical Manifestations
The most common manifestation of left ventricular failure is dyspnoea or a sense of breathlessness. This is caused predominantly by decreased lung compliance resulting from pulmonary edema and congestion, and by increased activity of autonomic stretch receptors within the lung. Dyspnoea is most noticeable during periods of physical activity. It is also prominent when the person is lying down (Orthopnoea), because of the increased amount of venous blood returned to the thorax from the lower extremities and because the diaphragm is elevated in this position.
Paroxysmal nocturnal dyspnea is an especially dramatic form of dyspnea that awakens the patients with sudden severe shortness of breath, accompanied by coughing, a choking sensation, and wheezing. Other manifestations of left ventricular failure include muscle fatigue, an enlarged heart, tachycardia, a third heart sound, and fine edematous pulmonary alveoli. With progressive ventricular dilation, the papillary muscles are displaced laterally, causing mitral regurgitation and a high-pitched systolic murmur. Chronic dilation of the left atrium may also occur and it is often associated with the development of atrial fibrillation manifested by an irregular heartbeat.
As CHF progresses, patients may become frankly cyanotic and acidotic owing to decreased tissue perfusion. Ventricular arrhythmias caused by myocardial irritability and overactivity of the sympathetic nervous system are common and are an important cause of sudden death in this setting.
Fluid Retention and Swelling:
- Puffy swelling (edema) in the legs, the feet, and the ankles may occur, particularly at the end of the day or after prolonged sitting. Often, the swelling is more noticeable in the ankles or on the lower leg in the front where the bone, the tibia, is close to the skin.
- Pitting edema can occur when pressing down on the skin in the puffy areas. The indentation where the finger pressed may be visible for a few minutes. Pitting edema is not synonymous with heart failure; it can have other causes, including liver and kidney failure. Non pitting edema is generally not caused by heart failure.
- Swelling may be so severe as to reach up to the hips, scrotum, abdominal wall, and eventually, the abdominal cavity (ascites).
- Daily weight checks are necessary for persons with heart failure because the amount of fluid retention is usually reflected by the amount of weight gain and increasing shortness of breath. Persons with heart failure should know their dry weight, which is what they weigh when they feel good with no pitting edema.
Treatment of CHF
Treatment of Congestive Cardiac Failure is focused on improving the symptoms and preventing the progression of the disease. The major and often neglected form of treatment is lifestyle improvement, which includes:
- Regulation of the salt and fluid intake: As the entire body suffers from congestion due to fluid accumulation and also that sodium leads to increased fluid accumulation in the body tissues, it is often recommended to restrict the sodium and fluid intake during cardiac failure.
- Exercise: It is recommended to do any activity which one can sustain for more than just a few minutes while your heart, lungs, and muscles work overtime. Such an exercise is known as aerobic exercise. Regular exercise, according to the patient’s tolerance level, appears to provide significant benefits and should be used only when the patient is compensated and stable.
Pharmacological Treatment
Pharmacological treatment involves the use of the following category of medications:
Inotropic Drugs:
- Cardiac glycosides: The digitalis glycosides are used due to their positive inotropic effect and negative chronotropic effect e.g. Digoxin, digitoxin, etc.
- Sympathomimetic amines: e.g. Dopamine dobutamine.
- Phosphodiesterase enzyme inhibitors: Amrinone and milrinone
ACE inhibitors: These agents act by inhibiting the Angiotensin-converting enzyme which is responsible for the conversion of Angiotensin I (inactive) to Angiotensin II (active). ACE Inhibitors improve symptoms, decrease mortality and reduce ventricular hypertrophy. E.g: Candesartan.
Diuretics: These remove excess extracellular fluid in patients with systolic or diastolic heart failure.
- Loop diuretics: Furesemide
- Potassium sparing diuretics: Amiloride
- Thiazide diuretics: Chlorthiazide, Hydrochlorthiazide
Surgical treatment: Heart transplantation may be recommended for a person who does not respond to medication.
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