The Heart Failure may be classified in several ways.
1. Acute versus chronic heart failure
2. Left versus right and biventricular failure
3. Forward versus backward failure
4. Systolic versus diastolic failure
5. Low output versus high output failure
Acute versus chronic heart failure:
Acute heart failure:
Heart failure developing suddenly in hours or days in a previously asymptomatic patient is called acute heart failure.
Chronic heart failure:
Heart failure developing gradually is called chronic heart failure. In this type of failure a variety of compensatory changes may take place in early phase to improve cardiac function. These adaptive mechanisms allow the patient to adjust and tolerate not only the anatomic abnormality but also a reduction in cardiac output with less difficulty.
Left versus right & biventricular heart:
Left sided heart failure:
Left-sided heart failure is characterized by reduction in effective left ventricular output for a given pulmonary venous or left atrial pressure.
An acute increase in left atrial pressure may cause pulmonary congestion or pulmonary edema, while chronic increase in left atrial pressure leads to reflex pulmonary vasoconstriction which protects increasing pulmonary hypertension (as a compensatory mechanism).
Causes of left heart failure
· Ischemic heart disease (commonest)
· Systemic hypertension
· Mitral and aortic valve disease
· Cardiomyopathies
Right sided heart failure:
Right-sided heart failure is characterized by reduction in right ventricular output for any given right atrial pressure. The increased right atrial pressure is manifested as an increased jugular venous pressure and as hepatic congestion.
Causes of right heart failure:
· Secondary to left heart failure (most common)
· Chronic lung disease (causing cor-pulmonale)
· Pulmonary embolism or pulmonary hypertension
· Tricuspid and pulmonary valve disease
· ASD & VSD
· Right ventricular cardiomyopathy
Biventricular or congestive cardiac failure (CCF)
When both sides of heart are involved, features of both right and left heart failure are present. In most of the patient right heart failure is a result of preexisting left heart failure.
Forward versus backward failure:
Forward failure:
In some patients with cardiac failure predominant problem in an inadequate cardiac output that leads to diminished perfusion of vital organs leading to ischemia of theses organs is called forward failure. Ischemia of brain causes mental confusion, ischemia of skeletal muscles leads to weakness, ischemia of kidneys causes sodium and water retention leading to symptoms of heart failure.
Backward failure:
In some patients cardiac failure presents mainly with features of damming of blood into venous system such as lung congestion in left heart failure and congestion of liver, spleen and other areas in right heart failure.
Systolic versus diastolic failure:
In majority of patients heart failure is due to combined systolic and diastolic dysfunction, however isolated systolic or diastolic dysfunction may be present.
Systolic failure:
Heart failure may develop as a result of impaired myocardial contraction (systolic dysfunction). The most common cause of systolic ventricular dysfunction is ischemic heart disease usually after myocardial infarction. The left ventricle is usually dilated and fails to contract normally resulting in symptoms of predominantly forward failure.
Diastolic failure:
Heart failure may develop due to poor ventricular filling caused by impaired ventricular relaxation (diastolic dysfunction). The most common cause is left ventricular hypertrophy as a result of hypertension and coronary artery disease. Other causes of diastolic dysfunction are hypertrophic and restrictive cardiomyopathy, diabetes and pericardial disease.
Diastolic failure is common in elderly, women and in patients with history of hypertension. It is a common cause of patient’s visit to doctor, patients present with shortness of breath and there is history of hypertension only (usually no history of previous MI).
Low versus high cardiac output failure:
Low output failure:
Low cardiac output at rest or during exertion characterizes heart failure caused by common conditions such as congenital, valvular, rheumatic, hypertensive, coronary and cardiomyopathic diseases. Low output failure presents with evidence of systemic vasoconstriction such as cold, paler or cyanotic extremities. Pulse pressure is low.
High cardiac output failure:
Conditions that are associated with a very high cardiac output such as anemia, beriberi, paget’s disease of bone and thyrotoxicosis may lead to or precipitate heart failure.
The extremities are usually warm, and flushed and pulse pressure is wide or normal. Detail of high output failure are given at the end of this section.
Chronic Heart Failure:
Heart failure developing is called chronic heart failure. In this type of failure a variety of compensatory changes may take place in early phases to improve cardiac function. These adaptive mechanisms allow the patient to adjust to and tolerate not only the anatomic abnormality but also a reduction in cardiac output with less difficulty.
As the disease progresses these compensatory mechanisms fail to improve cardiac function.
In compensated cardiac failure, patient has impaired cardiac function but the adaptive or compensatory changes prevent the development of overt cardiac failure. Theses compensatory changes are increased heart rate, hypertrophy of cardiac muscles an dilatation of heart chambers. Acute cardiac failure is uncompensated and therefore more symptomatic because time is required to develop theses compensatory changes to develop.
COMPENSATORY OR ADAPTIVE MECHANISMS IN THE HEART FAILURE:
A number of compensatory changes occur in the cardiovascular system in chronic heart failure to maintain adequate blood flow to the vital organs of the body as following:
MECHANISM ADVANTAGE DISADVANTAGE
IN LONG TERM
Sympathetic stimulation increased heart rate (as cardiac output Increases energy expenditure
Depends on stroke volume and heart rate).
Sympathetic stimulation causing increased
Arterial tone, increased heart rate and
Increased ventricular contractility.
Remodeling Ventricular hypertrophy and dilatation to Leads to deterioration and death
Maintain adequate blood flow. Of cardiac cells
Fluid water retention due Increases ventricular filling pressure Cause pulmonary congestion
To stimulation of rennin- (augment preload)
angiotensin system
The clinical features in cardiac failure are based on the two factors:
Reduced cardiac output (forward failure)
This results from decreased heart function. This reduced output leads to diminished filling of arterial tree, resulting in ischemia of the organs.
Damming of blood (backward failure)
Heart becomes fail o pump the whole blood coming to it, resulting in damming of blood back into venous system, organs become congested & their functions are distributed.
In majority of patients there is combination of both factors mentioned above.
