Chronic Heart Failure – Description, Causes and Risk Factors:
To understand what occurs in chronic heart failure, it helps to be familiar with the anatomy of the heart and how it works. The heart is composed of two independent pumping systems, one on the right side, and the other on the left. Each has two chambers, an atrium and a ventricle. The ventricles are the major pumps in the heart.
Right Side of the Heart: The right system receives blood from the veins of the whole body. This is “used” blood, which is poor in oxygen and rich in carbon dioxide.
The right atrium is the first chamber that receives blood.
- The chamber expands as its muscles relax to fill with blood that has returned from the body.
- The blood enters a second muscular chamber called the right ventricle.
- The right ventricle is one of the heart’s two major pumps. Its function is to pump the blood into the lungs.
- The lungs restore oxygen to the blood and exchange it with carbon dioxide, which is exhaled.
Left Side of the Heart: The left system receives blood from the lungs. This blood is now rich in oxygen.
The oxygen-rich blood returns through pulmonary veins (veins coming from the lungs) to the heart.
- The heart receives the oxygen-rich blood from the lungs in the left atrium, the first chamber on the left side.
- Here, it moves to the left ventricle, a powerful muscular chamber that pumps the blood back out to the body.
- The left ventricle is the strongest of the heart’s pumps. Its thicker muscles need to perform contractions powerful enough to force the blood to all parts of the body.
- This strong contraction produces systolic blood pressure (the first and higher number in blood pressure measurement). The lower number (diastolic blood pressure) is measured when the left ventricle relaxes to refill with blood between beats.
- Blood leaves the heart through the aorta, the major artery that feeds blood to the entire body.
The Valves: Valves are muscular flaps that open and close so blood will flow in the right direction. There are four valves in the heart:
The tricuspid regulates blood flow between the right atrium and the right ventricle.
- The pulmonary valve opens to allow blood to flow from the right ventricle to the lungs.
- The mitral valve regulates blood flow between the left atrium and the left ventricle.
- The aortic valve allows blood to flow from the left ventricle to the aorta.
The Heart’s Electrical System: The heartbeats are triggered and regulated by the conducting system, a network of specialized muscle cells that form an independent electrical system in the heart muscles. These cells are connected by channels that pass chemically-triggered electrical impulses.
Chronic heart failure (CHF) is a complex clinical syndrome that can result from any structural or functional cardiac or non-cardiac disorder that impairs the ability of the heart to respond to physiological demands for increased cardiac output. CHF is characterized by symptoms such as exertional breathlessness and fatigue, and signs of fluid retention as well as signs associated with the underlying cardiac disorder.
Chronic heart failure may arise as a consequence of a myocardial, valvular, pericardial, endocardial or electrical problem (or combination of these). In contrast with chronic heart failure, the term acute heart failure is often used to mean acute (cardiogenic) dyspnoea characterized by signs of pulmonary congestion including pulmonary edema.
The commonest cause of chronic heart failure is myocardial dysfunction which is commonly systolic, that is there is reduced left ventricular contraction. Around 2/3rd of these cases result from CHD (coronary heart disease) and there is usually past history of MI (myocardial infarction).
Other causes may be:
Coronary Artery Disease – Coronary artery disease (CAD), a disease of the arteries that supply blood and oxygen to the heart, causes decreased blood flow to the heart muscle. If the arteries become blocked, the heart becomes starved of oxygen and nutrients.
- Heart Attack – A heart attack may occur when a coronary artery becomes suddenly blocked, stopping the flow of blood to the heart muscle and damaging it. The damaged heart muscle does not function properly.
- Cardiomyopathy – Damage to the heart muscle may be caused by infections or alcohol or drug abuse, pregnancy or no apparent cause.
- Strain on the Heart – Conditions including high blood pressure (hypertension), valve disease, thyroid disease, kidney disease, diabetes or heart defects present at birth can all cause Heart Failure.
- High Blood Pressure (Hypertension) – Increases the workload on heart muscle.
- Diseases of Valves of Heart – Improper functioning of heart valves leads to increased work load and stress on heart muscle.
- Diseases of Muscle of Heart – The muscle of heart is diseased and not functioning properly. It is also known as cardiomyopathy.
- Birth Defects of Heart – Abnormal development of heart leads to variety of structural defects, which are present since birth. Also known as congenital heart disease.
Advancing Age: Heart failure is the most common reason for hospitalization in the elderly, and as the population ages, the incidence of heart failure is rising dramatically. According to one report, it occurs at a rate of about 10 in 1,000 people after age 65. The positive implication is, however, that people are living longer with heart failure.
- Gender: Men are at higher risk for heart failure than women, although the difference narrows with age. Women also have a better survival rate than men do when heart failure is caused by valvular heart disease, high blood pressure, or alcohol abuse. The survival rates of women and men are more similar, however, when heart failure evolves from coronary artery disease or heart attack. Women are much more likely to develop heart failure after a heart attack than men. In such cases, some evidence suggests that the reasons for this may include less aggressive approaches to treatment for the initial heart conditions.
- Ethnicity: African-Americans may be at higher risk for heart failure than Caucasians, and studies have reported that they tend to do much worse. Some evidence suggests that African-Americans are more often likely than Caucasians to develop diastolic heart failure, which is often a precursor to systolic heart failure. Caucasians tend to develop systolic heart failure first.
- Family History and Genetics: People whose parents had heart failure have a greatly increased risk of developing heart failure, particularly left-ventricular systolic heart failure.
- Diabetes: People with diabetes are at high risk for heart failure, particularly if they also have coronary artery disease. Even blood sugar abnormalities that precede diabetes increase the risk.
- Obesity: Obesity is associated with both hypertension and type II diabetes, conditions that place people at risk for heart failure. Evidence strongly suggests that obesity itself is a major risk factor for heart failure, particularly in women.
- Thyroid Problems: An overactive thyroid or underactive thyroid can have severe effects on the heart and increase the risk for heart failure.
Chronic Heart Failure – Symptoms:
The main symptoms of chronic heart failure are:
- Severe tiredness or fatigue.
- Shortness of breath (dyspnoea).
- Swelling of the ankles.
Your doctor will diagnose chronic heart failure based on your medical and family histories, a physical exam, and tests. Because the symptoms of chronic heart failure are common in other conditions too.
Medical and Family Histories: Your doctor will ask whether you or others in your family have or have had a disease or condition that can cause heart failure. Your doctor also will ask about your symptoms. He or she will want to know which symptoms you’ve have, when they occur, how long you’ve had them, and how severe they are. The answers will help show whether and how much your symptoms limit your daily routine.
Physical Exam: During the physical exam, your doctor will:
Measure your pulse rate.
- Measure your blood pressure.
- Listen to your heart for sounds that aren’t normal.
- Listen to your lungs for the sounds of extra fluid buildup.
- Look for swelling in your ankles, feet, legs, abdomen, and the veins in your neck.
- Take some blood and urine samples to find out if you have anemia, liver damage, kidney damage, or thyroid disease.
- Take an x-ray of your chest. The chest x-ray is important to help exclude other causes of shortness of breath and other support possible diagnosis of chronic heart failure. On its own it cannot be used to diagnose heart failure and must be used in combination of other sources of clinical evidence.
Imaging Studies May include:
Electrocardiogram (EKG): Enlargement of the heart muscle, which may help to determine long-term outlook, the presence of coronary artery disease, abnormal cardiac rhythms, a finding called a prolonged QT interval may predict people with heart failure who are at risk for severe complications and would need more aggressive therapies.
- BNP (brain natriuretic peptide) monitoring: This test monitor your brain functioning. If you have chronic heart failure the level of BNP is your blood is increased.
- Exercise Stress Test: The exercise stress test measures heart rate, blood pressure, and electrocardiographic changes. It is an important diagnostic component in determining heart failure symptoms. Doctors also use exercise tests to gauge long-term outlook and the effects of particular treatments.
- Echocardiography: The best diagnostic test for heart failure is echocardiography. Echocardiography is a noninvasive, entirely safe test that uses ultrasound to image the heart as it is beating.Cardiac ultrasounds provide the following information:
- Accurate indications of valve function.
- Important measurements about how well the heart is pumping, especially a measurement called left ventricle ejection fraction (LVEF).
- The location of the failure and where it has occurred.
- Changes in the structure of the heart that may be a result of heart failure
Doctors use information from the echocardiogram for calculating the ejection fraction (how much blood is pumped out during each heartbeat), which is important for determining the severity of heart failure.
Holter monitor: A Holter monitor is a small box that you carry in a pouch around your neck or clipped to your belt. It’s attached to sticky patches called electrodes that are placed on your chest. The device records your heart rhythm for a full 24- or 48-hour period, while you do your normal daily activities.
- Nuclear Heart Scan: A nuclear heart scan is a test that shows how well blood is passing through your heart and how much blood is reaching your heart muscle. Your doctor will inject a radioactive substance into your bloodstream, which will make your heart chambers and vessels easy to see. Then, a special camera is used to show where the substance lights up (in healthy heart muscle) and where it doesn’t (in damaged heart muscle).
- Cardiac Catheterization: During cardiac catheterization a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck and threaded to your heart. This allows your doctor to study the insides of your coronary arteries. Coronary arteries carry oxygen-rich blood to your heart.
- During this procedure, your doctor can check the pressure and blood flow in the heart’s chambers, collect blood samples, and use x rays to look at the coronary arteries.
- Coronary Angiography: Coronary angiography is usually done with cardiac catheterization. A dye that can be seen on x ray is injected into the blood through the tip of the catheter. The dye allows your doctor to see the flow of blood to the heart muscle. This test also shows how well your heart is pumping.
- Cardiac Magnetic Resonance Imaging (MRI): A cardiac MRI scan shows, in detail, the structures and beating of your heart. An MRI scan can help your doctor see whether parts of your heart are damaged.
- Positron Emission Tomography (PET): PET scanning shows the level of chemical activity in areas of your heart. This scan can help your doctor see whether enough blood is flowing to these areas. It can show blood flow problems that other types of scans may not pick up.
Alcohol Consumption: All patients with chronic heart failure must refrain from excessive alcohol consumption. When the etiology of the heart failure is alcohol related, patient should be strongly encouraged to stop drinking alcohol.
Smoking: Patient with chronic heart failure should be strongly advised not to smoke and should be offered smoking cessation advice and support.
- Patient with chronic heart failure should be advised to avoid salt intake greater than 6 g/day.
- Patient with chronic heart failure who are taking warfarin should be advised to avoid cranberry juice.
- Patient with chronic heart failure who are taking simvastatin should be advised to avoid grapefruit juice.
A large number of high quality trials on pharmacological therapy have been undertaken in patient with LVSD with all stages of disease from asymptomatic LVSD to severe heart failure. The aims of the treatment are to prevent progression of the disease thereby reducing symptoms.
Angiotensin converting enzymes inhibitors should be considered in patients with all functional classes of heart failure due to left ventricular systolic dysfunction (LVSD).
All patients with heart failure due to LVSD of all functional classes should be started on beta blocker therapy as soon as their condition is stable (unless contradicted by a history of asthma, heart block or symptomatic hypotension)
Angiotensin Receptor Blockers: Patient with chronic heart failure due to LVSD alone or heart failure, who are intolerant of Angiotensin converting enzyme should be considered Angiotensin receptor blocker.
Diuretics: In the majority of patients with heart failure, fluid retention occurs, causing ankle and pulmonary edema, and contribute to the symptom of dyspnoea. Diuretic treatment relieves edema.
Digoxin should be considered as an add-on therapy for heart failure patient in sinus rhythm who are still symptomatic after optimum therapy.
Cardiac Resynchronisation Therapy (CRT): In addition to optimal medical therapy in terms of improving exercise capacity, improving quality of life, and reducing hospitalization CRT showed significant improvement.
CRT using a pacing device is recommended as a possible treatment for people with heart failure where all of the following circumstances apply.
They have moderate to severe symptoms of heart failure that are affecting their daily life, measuring class 3 or class 4.
- Their heart is beating regularly but an electrocardiogram (ECG) shows that the electrical system of the heart is not working properly.
- The left ventricle of their heart is pumping out less than 35% of its normal amount of blood (called the left ventricular ejection fraction).
- They are taking the drug treatment that is most effective for them.
Implantable cardiac defibrillators are an important part of the management of patients with chronic heart failure. Some patient with high risk will require defibrillator in conjunction with CRT.
Patient with obstructive sleep apnea and heart failure may be safely treated with CPAP (continuous positive airway pressure).
Moderate intensity supervised exercise training program is also necessary to improve exercise tolerance and quality of life.
Surgeries may be:
Coronary artery bypass grafting.
- Intra-aortic balloon counter pulsation.
- Cardiac transplantation.
Comprehensive discharge planning should be ensure that links with post-discharge services are in place for all those with symptomatic heart failure. A nurse led, home based element should be included.
Disclaimer: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.