Difference Between Compensated and Decompensated Heart Failure

The inability of the heart to pump blood adequately to fulfil the metabolic demands of peripheral tissues is known as the heart failure. When there is a reduction in the cardiac output in the initial stage of heart failure, it triggers several structural and functional changes in the cardiac tissues as a measure of restoring the cardiac output. This is known as the compensated heart failure. At one point, these adaptive changes fail to maintain the desired cardiac output giving rise to the decompensated heart failure. The patient remains either asymptomatic or minimally symptomatic in the compensated heart failure and becomes symptomatic in the decompensated heart failure. This is the key difference between compensated and decompensated heart failure.

CONTENTS

1. Overview and Key Difference
2. What is Heart Failure
3. What is Compensated  Heart Failure
4. What is Decompensated Heart Failure
5. Similarities Between Compensated and Decompensated Heart Failure
6. Side by Side Comparison –Compensated vs Decompensated Heart Failure  in Tabular Form
7. Summary

What is Heart Failure?

The inability of the heart to pump blood adequately to fulfil the metabolic demands of peripheral tissues is known as heart failure. Heart failure can be categorized into two categories as right heart failure and left heart failure, depending on the side of the ventricle whose pumping capacity is impaired.

When the heart fails to pump blood adequately to the body tissues due to the decrease in the pumping capacity of the right heart chambers, this condition is identified as the right heart failure.

On most occasions, the right-sided heart failure occurs secondary to the left-sided heart failures. When the left side of the heart, precisely the left ventricle, fails to pump blood adequately into the aorta, blood is collected inside the left heart chambers. As a result, the pressure inside these chambers increases, impairing the drainage of blood into the left atrium from the lungs via the pulmonary veins. Consequently, the pressure inside the pulmonary vasculature is raised. Thus, the right ventricle contracts more vigorously against a higher resistive pressure to pump blood into the lungs. With the long-term prevalence of this condition, heart muscles of the right chambers start to wear down ultimately, resulting in the right-sided heart failure.

Although not frequently seen, right-sided heart failure can also be caused by different intrinsic pulmonary pathologies such as bronchiectasis, COPD, and pulmonary thromboembolism.  

Effects

• Edema in the dependent regions of the body such as ankles – in more advanced stages, the patient can also get ascites and pleural effusion
• Congestive organomegaly such as hepatomegaly

The inability of the heart to pump blood to adequately fulfil the metabolic demand of the body is called heart failure. The condition caused by the failure due to the faltering of the pumping capacity of the left heart chambers is known as left-sided heart failure.

Causes

• Ischemic heart diseases
• Hypertension
• Aortic and mitral valve diseases
• Other myocardial diseases such as myocarditis

Left-sided heart failure is accompanied by certain morphological changes in the heart. The left ventricle undergoes compensatory hypertrophy, and both the left ventricle and atrium are dilated due to the transmission of increased pressure. The dilated left atrium is particularly susceptible to get atrial fibrillation. A fibrillating atrium is at a higher risk of having thrombi formed inside it.

Effects

• The reduction of blood supply to the brain can result in hypoxic encephalopathy in the most advanced cases
• Pulmonary edema caused by the secondary pooling of blood inside the lungs
• Long-standing left heart failure can give rise to right heart failure as well.

Clinical Features of Heart Failure

Most clinical features of left and right heart failure are similar to each other. As explained before, left heart failure is most often the cause of right heart failure. So the concurrent presence of both conditions gives a clinical picture with plenty of shared symptoms and signs. The frequently seen symptoms that give the physicians a clue about the disease are,

• Exertional dyspnea
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Fatigue and faintishness
• Cough
• Edema in the dependent regions of the body such as ankles – In bed-bound patients, edema will be seen in the sacral regions. This is more pronounced in the right-sided heart failure due to the decrease in the venous return which leads to the pooling of blood in the dependent regions of the body.
• Organomegaly

This is also due to the venous congestion. Consequently, features of organomegaly are seen in right heart failure or when the right heart failure is present together with the left heart failure. Liver enlargement (hepatomegaly) is associated with the abnormal distension of the stomach,  the appearance of veins around the umbilicus (caput medusae)  and failure of the liver functions.

Diagnosis of Heart Failure

Heart failure is confirmed by the following investigations.

• Chest X-ray
• Blood tests – including FBC, liver biochemistry, cardiac enzymes released in acute cardiac failure and BNP
• Echocardiogram
• Electrocardiogram
• Stress echocardiography
• Cardiac MRI (CMR)
• Cardiac biopsy – carried out only when a cardiac myopathy is suspected
• Cardiopulmonary exercise testing

Treatment of Heart Failure

• Lifestyle modifications play a key role in preventing further deterioration of the heart muscles while reducing the risk of complications such as cardiac arrhythmias. After being diagnosed with heart failure, all patients are advised to minimize the consumption of alcohol and to control their body weight. Low sodium and low salt diet are ideal for a heart patient. Bed rest is usually recommended since it minimizes the stress on the cardiac muscles.

– The drugs given in the management of heart failure include

• Diuretics
• Angiotensin converting enzyme inhibitors
• Angiotensin II receptor antagonists
• Beta blockers
• Aldosterone antagonists
• Vasodilators
• Cardiac glycosides

– Nonpharmacological interventions used in managing heart failure are

• Revascularization
• Use of biventricular pacemaker or implantable cardioverter defibrillator
• Cardiac transplantation

What is Compensated Heart Failure?

When there is a decrease in the pumping capacity of the heart, certain adaptive changes happen to compensate for the lack of blood supply to the peripheries. These changes include left ventricular hypertrophy, development of collateral circulation in the ischemic heart diseases and etc. There is an increase in the rate of the heartbeat as well.  As a result, cardiac functional capacity is restored. Thus most of the clinical manifestations are masked, and the patient remains either asymptomatic or minimally symptomatic. This stage of heart failure where there is a decrease in the pumping capacity of the heart without the patient becoming symptomatic is known as the compensated heart failure.

What is Decompensated Heart Failure?

The adaptive structural and functional changes happening in the heart during the compensated stage initiate a vicious cycle of events that worsen the cardiac functional status. When there is left ventricular hypertrophy with an increase in the muscle mass, the already compromised coronary circulation finds it difficult to supply blood adequately to the increased muscle bulk. Therefore ischemic damage to the myocardium is aggravated. At the same time, increase in the heart rate decreases the stroke volume because there is not enough time for the ventricle to get filled. Consequently, the cardiac output decreases giving rise to the clinical manifestations which were discussed above. This stage if heart failure is known as the decompensated heart failure.

What are the Similarities Between Compensated and Decompensated Heart Failure?

• In both conditions, there is an underlying reduction in the cardiac output.
• Investigations used for the identification of both types of heart failures are the same

What is the Difference Between Compensated and Decompensated Heart Failure?

Summary – Compensated vs Decompensated Heart Failure

Adaptive changes in the cardiac tissues maintain an optimal cardiac output although the damages to the myocardium in heart failure is known as the compensated heart failure. Failure of these adaptive changes to maintain the cardiac output at the same optimal level with disease progression is known as the decompensated heart failure. In compensated heart failure, the patient remains either asymptomatic or minimally symptomatic whereas in decompensated heart failure the patient becomes severely symptomatic. This is the main difference between compensated and decompensated heart failure.

Reference:

1.Kumar, Parveen J., and Michael L. Clark. Kumar & Clark clinical medicine. Edinburgh: W.B. Saunders, 2009.

Image Courtesy:

1. “Heart diagram-en” By ZooFari – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “1846050” (CC0) via Pexels