What is heart failure?Sunday, February 21, 2021
DR PAUL EDWARDS and DR ERNEST MADU
A common heart condition which has been increasing in prevalence over the past few decades worldwide is that of heart failure.
Given this increase, we as cardiologists find that an increasing number of our patients are not well informed about this condition and the measures involved in evaluation and treatment. We will thus devote this week's column to delving into these issues.
What is heart failure?
The heart can simply be thought of as a pump, whose function is to ensure that blood with oxygen and nutrients are sent out to the tissues and organs of the body. The pumping chambers of the heart — “the ventricles” — contract, increasing the pressure in the heart and driving blood forward through the lungs, where oxygen is acquired and then onto the various tissues of the body. The blood then returns to the lungs and heart and is pumped out again.
In this simple model, an important concept to note is that the heart does not “decide” how much blood should be pumped. The tissues of the body have a need for oxygen and nutrients that can vary from minute to minute and the role of the heart is to pump enough blood so that these needs are met. A normal heart is able to meet the normal demands of the body.
What then is heart failure? Heart failure can simply be thought of as the inability of the heart to meet the demands of the body. This condition is usually due to some disease process affecting the structure and function of the heart.
What are the types and causes of heart failure?
Heart failure can be divided into two types. The first type is known as systolic heart failure. In this condition the pumping function of the heart is impaired. The pumping chamber on the left side of the heart — the left ventricle — normally empties more the 50 per cent of the blood in the chamber with each contraction.
Systolic heart failure may be thought of as weakening of the heart muscle. Common causes of systolic heart failure include heart attack or myocardial infarction. In this condition heart muscle dies and thus is no longer able to contract.
Long-standing poorly controlled hypertension can also result in weakening of the muscle of the heart. Other less common causes include disease of the heart valves, inflammation of the heart, chemotherapy, alcoholism, etc.
The second type of heart failure is known as diastolic heart failure. In this condition the pumping function of the heart is normal, and the issue is one of filling of the heart. Normally the pressure in the chambers of the heart prior to contraction is low and this allows the heart to fill with blood which can then be pumped forward.
In diastolic heart failure, the walls of the heart can be thought to be “stiffer” than normal and the heart is unable to fill adequately. One can think of the normal heart as a balloon which can be inflated easily with one's breath. A heart with diastolic heart failure can be thought of as being like a car tire which requires high pressures to fill. If the heart cannot fill adequately prior to contraction, then less blood will be pumped forward with each beat. The amount of blood pumped can be insufficient to meet bodily demands. Long-standing poorly controlled hypertension is the most common cause of diastolic heart failure. Other causes include diabetes, valvular heart disease, genetic conditions resulting in infiltration of the heart or thickening of heart muscle, etc.
What are the symptoms of heart failure?
The symptoms of heart failure are related to the issues that we have outlined above. We can divide these symptoms into two major groups. Those related to not enough blood flow reaching the tissues of the body and those symptoms related to blood not returning to the heart.
Poor blood flow to the tissues of the body can result in poor activity or exercise tolerance as exercising muscles are not receiving adequate blood flow. Initially, patients notice problems with higher levels of exertion such as climbing a flight of stairs, carrying groceries, or running. As heart failure progresses, lower levels of exertion can be difficult. Patients with advanced heart failure can have symptoms walking from room to room at home. Patients will complain of feeling tired and not having energy. There can sometimes be symptoms of dizziness as well.
The second group of symptoms is related to the pooling of blood secondary to high pressures in the heart. Blood can pool in the lungs resulting in symptoms of shortness of breath, particularly with exertion or at nights when lying flat in bed. Blood pooling in the legs can result in swelling or edema. Upper abdominal pain from liver congestion, bloating, poor appetite and early satiety from bowel wall congestion are common findings. Other less common symptoms include passing out, palpitations, weight loss, loss of muscle mass, lower leg skin changes, etc.
It should be noted that the symptoms of heart failure are not necessarily diagnostic on their own and similar symptoms can be seen in patients with other conditions including kidney disease, liver disease, morbid obesity, lung disease, etc. Given this finding, a diagnosis of heart failure usually requires confirmatory testing with an ultrasound of the heart.
Why is heart failure important?
Heart failure has been increasing in prevalence on a worldwide basis and is an important clinical problem in Jamaica and the Caribbean. Unfortunately, epidemiologic data is lacking for Jamaica and the Caribbean region. In the United States, 6.5 million adults are estimated to have heart failure. In the population greater than 40 years of age, the lifetime risk of heart failure is one in four. In the elderly United States population, the prevalence of heart failure is estimated to increase by 46 per cent by the year 2030. Anecdotally, it does appear that the prevalence of heart failure is increasing in most of the developing world including the Caribbean region, South America and the African continent. However, large-scale epidemiologic studies have yet to be performed.
From a clinical point of view it is an important cause of patient morbidity and mortality. Often, our patients are surprised to know that the average risk of dying for a patient with heart failure is 50 per cent at five years (ie, one in two will be dead in five years).
What is often not acknowledged is that this mortality risk is higher than many cancers. For US women, the risk of developing heart failure is about one in six which is higher than the lifetime risk of breast cancer which is one in eight.
Aside from the issue of mortality, heart failure is a morbid condition with significant adverse impact on quality of life, ability to maintain gainful employment, need for repeated hospitalisation and physician visits. There are also important economic costs to the heart failure epidemic. These include direct medical costs. Data from the United States of America suggest that total medical costs for heart failure in 2012 totaled US$30.7 billion. This does not include indirect costs related to loss productivity of the patient and family members.
Because of the limited access to adequate care for many patients in Jamaica resulting in delayed diagnosis and treatment, the impact on life expectancy and quality of life as well as direct and indirect economic costs of heart failure in Jamaica are believed to be very significant
In future articles we will address issues of prevention, diagnosis, and treatment of heart failure.
Dr Ernest Madu, MD, FACC, and Dr Paul Edwards, MD, FACC are Consultant Cardiologists at Heart Institute of the Caribbean (HIC) and HIC Heart Hospital
Dr Madu is a main TED Speaker whose TED talk has been translated into 19 languages, seen, and shared by more than 500,000 viewers. He has received the Distinguished Cardiologist Award, the highest award from the American College of Cardiology and has been named among the 100 most influential people in health care and among the 30 most influential in public health. Dr Madu is also a recipient of the Global Health Champion Award from the University of Pennsylvania. He is the past CEO of HIC and is currently the Chairman of IHS Holdings Ltd, an asset management company with interests in the USA, Africa, and the Caribbean.
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