By National Heart, Lung, and Blood Institute, National Institutes of Health, Public Domain, Wikimedia
Heart failure occurs when the heart is unable to pump enough blood to meet the body's demands. The heart functions as a pump that helps to distribute blood to the various tissues and organs of the body from where they get the oxygen and nutrients for their normal function. When the heart fails to pump out enough blood to meet up these demands, the heart is said to have failed.
This heart failure can be in many forms. There can an acute heart failure which occurs rapidly and suddenly or chronic heart failure which happens gradually over months or years. There is also left heart failure which affects mainly the left part of the heart, or right heart failure which affects the right part of the heart.
Another form of heart failure is systolic heart failure which occurs when the heart chambers are unable to contract to pump blood or diastolic heart failure which occurs when the heart chambers are unable to relax to fill its chambers with blood. There can also be a high output failure where the heart is pumping out blood normally but the body's demands outweigh the normal volume pumped out by the heart. Such high-output states include pregnancy, thyrotoxicosis, or anaemia.
In all these, the summary of the outcome of heart failure is symptoms from congestion and poor perfusion. In normal blood circulation, the used blood (deoxygenated blood) from the body's cells and tissues is collected and returned to the heart through the blood vessels called the Superior and Inferior vena cava which empties into the upper right chamber of the heart (Right atrium). From there, the blood flows into the right lower chamber of the heart (right ventricle) which then pumps the blood to the lungs through the pulmonary artery. In the lungs, the blood is oxygenated for use by the tissues.
The oxygenated blood from the lungs is then sent into the upper left chamber of the heart called the left atrium through the pulmonary vein. From the left atrium, the blood moves into the lower left chamber of the heart called the left ventricle, from where the blood is then pumped to the rest part of the body through the aorta.
By Wapcaplet - Own work, CC BY-SA 3.0, Wikimedia
Understanding this blood flow through the heart helps us to understand the symptoms that occur in heart failure.
In right heart failure, the heart is unable to receive the deoxygenated blood returning from the general (systemic) circulation. Therefore there is an accumulation of blood in the vessels since then cannot return to the heart. These lead to symptoms of systemic congestion.
Symptoms and signs of systemic congestion in heart failure include distended neck veins, raised jugular venous pressure, fluid accumulation in the abdomen (ascites), swelling of the liver (hepatomegaly), leg swelling for those moving around (pedal edema) or swelling around the waist for those lying down (sacral edema), easy satiety etc.
For left heart failure, the heart is unable to receive the oxygenated blood from the lungs, so there is a backflow of blood to the lungs causing pulmonary congestion. This pulmonary congestion presents as breathlessness, difficulty in breathing while lying down (orthopnea) and sudden breathing difficulty at night which wakes the patient up from sleep (paroxysmal nocturnal dyspnea), night cough which may be productive of pink frothy sputum.
In both, the heart is also unable to pump enough blood out to the circulation, therefore there are features of poor perfusion. Clinical features of poor perfusion include tiredness on any little activity, exercise intolerance, signs of shock like low blood pressure, fast and thready pulse, cold and clammy extremities, etc.
By Myupchar, CC BY-SA 4.0, Wikimedia
CAUSES OF HEART FAILURE
There are many causes of heart failure, but the common causes here include:
Hypertension: This is a very common cause of heart failure. In people who have prolonged uncontrolled hypertension, it causes the heart to work hard to pump blood to the rest part of the body. Since the left ventricle pumps blood to the rest of the body, over time, it thickens due to this hard work. This thickening is called left ventricular hypertrophy and results in heart failure over time.
Coronary artery disease: This is the most common cause of heart failure and results from the occlusion of the blood vessels that supply blood to the heart. This causes the heart muscles to die off due to a lack of blood and oxygen. It can weaken the heart muscle and also causes abnormal electrical activities of the heart. These cumulatively result in heart failure.
Valvular heart disease: The movement of the blood in and out of the heart chambers is controlled by heart valves. When these valves are malfunctioning, either it gets too weak and allows the backflow of blood or it gets stiff (stenosed) and does not allow normal blood flow, it impairs the function of the heart. When the valves are stenosed, the heart works harder than normal trying to force blood through the stenosed valve. These lead to heart failure.
Cardiac Arrhythmia: Arrhythmia is an abnormal heart rhythm. When there is an alteration in the electrical activities of the heart, it can make the heart beat too fast or too slow. When the heart beats too fast, especially atrial fibrillation, it can lead to the formation of blood clots in the heart. It also makes the heart work harder than normal and impairs the blood pumped out by the heart. They all predispose to heart failure.
Congenital heart diseases: Some persons are born with some abnormalities in their heart structure, either the chambers are not fully partitioned or the valves are not working well. These alter the normal functioning of the heart and result in heart failure.
Diseases of the heart muscles (Cardiomyopathies): Certain diseases affecting the heart muscles cause them to be abnormally dilated or hypertrophied. These changes in the structure of the heart muscles will increase the muscle's oxygen demand, alter the electrical activities and impair its normal contractility and function. The endpoint is heart failure.
Inflammation of the structures of the heart: Inflammation of the heart muscles (myocarditis) or the heart covering (pericarditis) or the inner lining of the heart chambers (infective endocarditis) as well as other diseases like rheumatic heart diseases will eventually alter the heart's function and can predispose to heart failure.
Conditions of low oxygen supply to the tissues (hypoxia) and previous heart surgery can also cause heart failure.
The predisposing factors to heart failure include certain drugs, alcohol, pulmonary embolism, high output states like anemia and pregnancy, uncontrolled hypertension, infection, etc.
By James Heilman, MD - Own work, CC BY-SA 3.0, Wikimedia
HOW DOES HEART FAILURE OCCUR
The pathophysiology of heart failure is complex, but in a simple summary, heart failure results from an event that alters the ability of the heart to pump blood to the tissues. The body will sense this drop in the amount of blood pumped by the heart and then try to make up for it.
It does this by activating the various compensatory mechanisms, chiefly the Renin-angiotensin-aldosterone system, the sympathetic nervous system, and other neurohormonal mechanisms. These systems make the heart and vessels try to meet up with the decline in tissue perfusion by narrowing the blood vessels, making the heart beat faster, salt and water retention in the body, etc.
In the beginning, these compensatory mechanisms help the heart to improve heart functions, but continuous activation of these compensatory mechanisms eventually results in tissue damage to the ventricles and the heart then fails.
WHY DO WE NEED TO KNOW ABOUT THIS?
According to the Centre for Disease Control (CDC);
About 6.2 million adults in the United States have heart failure.
In 2018, heart failure was mentioned on 379,800 death certificates (13.4%).
Heart failure costs the nation an estimated $30.7 billion in 2012. This total includes the cost of health care services, medicines to treat heart failure, and missed days of work.
CLINICAL FEATURES
The main symptoms of heart failure are difficulty in breathing, ankle swelling, and tiredness following any small activity. Other clinical features as stated above are abdominal distension, getting easily filled after a small meal, right upper abdominal pain, night cough, orthopnea, PND, etc.
INVESTIGATIONS
For patients suspected to have heart failure, there are important investigations that need to be done.
They include an Electrocardiogram which shows any abnormal heart rhythm, abnormal enlargement of the heart chambers, etc. An echocardiogram confirms the diagnosis and identifies the cause. A chest x-ray will show an accumulation of fluid in the alveoli and the interstitium, enlargement of the heart, upper lobe diversion, and pleural effusion.
By CDC/ Dr. Thomas Hooten - Public Health Image Library (PHIL), Image 6241, Public Domain, Wikimedia
Other important investigations will include Serum electrolytes, urea, and creatinine which is done to check kidney function, and Brain natriuretic Peptide which is very sensitive but not specific in the diagnosis of heart failure. Thyroid function test, Urinalysis, full blood count, lipid profile, etc are also done.
TREATMENT
The treatment of Chronic heart failure, like other chronic conditions, is for a very long time/lifetime. Therefore, the first step in the management here is to properly educate the patient on his condition, the cause, and the treatment options. The patient also needs to be educated on the importance of drug compliance and lifestyle modification. The patient is incorporated as a partner in his treatment which improves compliance with drugs.
The next step is the need for diet and lifestyle modifications. There is a need to limit salt and water intake and eat healthy foods, fruits, and vegetables. The patient also needs to stop alcohol, and smoking and also maintain a healthy weight.
Vaccination against influenza and pneumococcal organisms is also very important as these infections may precipitate acute heart failure.
The drug treatment for chronic heart failure includes diuretics which help to remove the excess fluid accumulation in the body. Angiotensin Converting Enzyme Inhibitors (ACEIs) and Angiotensin Receptor Blockers (ARBs) are used to block the negative effects of RAAS activation.
Beta-blockers are another group of drugs given to reduce the heart rate and myocardial oxygen demands as well as reduce the sympathetic effect on the heart. Cardiac glycosides like digoxin, positive inotropes, vasodilator, etc can be given when indicated.
Surgical options may include an implantable cardiac defibrillator, coronary artery bypass graft for those who have coronary artery disease, ventricular assist device, or even a heart transplant.
PREVENTION
Heart failure is a very serious disease. It is commoner with advancing age but also occurs in any age group. The rate of death from heart disease can be as high as 50%, therefore, prevention remains our best bet here.
We can achieve this by avoiding all the risk factors and causes listed above. Those who have hypertension should maintain optimum control of their blood pressure to avoid this complication. It is also important to maintain adequate body weight and fat to avoid coronary artery diseases.
Smoking and excessive alcohol intake are key risk factors that should be avoided. Maintain physical activity and exercise regularly. Eat a healthy balanced diet and avoid a high-cholesterol diet. Sleep well, avoid excessive stress, and illegal drugs, and also try to go for regular checks up.
By Funk Dooby from Kent, UK - FNK_4020, CC BY-SA 2.0, Wikimedia
With these, we can greatly reduce the risk of heart failure.
Thank you so much for reading.
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