What are the causes?
Published in The Business Times on 12 August 2018
By Senior Consultant Cardiologist, Dr Wong Siong Sung
Heart failure is a condition where the heart is no longer able to pump effectively to supply adequate blood in order to meet the demands of the body. 2017 American Heart Association (AHA) data showed that heart failure affects about 6.5 million Americans aged 20 years and older. The lifetime risk of developing congestive heart failure is 1 in 5 for both men and women. The prevalence of heart failure increases as peoples get older. Heart failure can be divided into two categories, i.e. heart failure with preserved ejection fraction and heart failure with reduced ejection fraction. Patient with heart failure may experience shortness of breath on exertion or at rest, orthopnoea (breathlessness that occurs while lying flat), lightheadedness, fatigue, nausea, palpitation, fluid overloaded with abdominal distension and leg swelling. There is significantly higher death rate among those who are diagnosed to have heart failure. Therefore, it is important to know what causes the heart failure.
The causes of the heart failure include the following:
1. Coronary Heart Disease
Significant heart artery disease can frequently lead to heart failure. The heart muscle does not receive sufficient blood supply to meet its needs due to the narrowed heart artery. As a result, the heart muscle is not able to contract normally although it is still alive (hibernating myocardium).
Besides, patient who suffered from acute myocardial infarction (heart attack) as a result of occlusion of heart artery will also experience heart failure. In such scenario, part of the heart muscle is dead or non-viable as there is no blood supply to the affected heart muscle supplied by the occluded heart artery. As the heart muscle is dead, it can no longer contract normally. Consequently, this results in heart failure. The larger the extent of heart muscle damage, the greater the severity of heart failure.
There are times heart failure is caused by the reduced contractile function of the affected heart muscle even though the blood supply to the heart muscle was restored with treatment, for instance, coronary artery stenting for the coronary artery blockage. In such case, the heart muscle is still alive but with impaired function for a period of time (stunned myocardium).
In Singapore, about one third of the deaths are due to cardiovascular disease where close to 6000 peoples died from cardiovascular disease annually with about 16 deaths a day. Coronary heart disease is one of the most important conditions to diagnose when evaluating a patient with heart failure.
2. High Blood Pressure
High blood pressure (hypertension) significantly increases the risk of heart failure.
People with long standing high blood pressure can develop left ventricular hypertrophy (thickening of the heart muscle). Among peoples who are diagnosed with heart failure, antecedent evidence of left ventricular hypertrophy is present in approximately 20% by electrocardiogram and 60 to 70% by echocardiogram criteria.
3. Valvular Heart Disease
Significant aortic or mitral valve disease (stenosis or regurgitation) can lead to heart failure. is a condition in which the between the left ventricle (pumping chamber of our and the aorta (main artery to our body) does not work properly. Aortic valve disease can occur as a result of degenerative calcification due to advanced age, bicuspid valve (certain people are born with aortic valve that has two cusps instead of three) or rheumatic heart disease (heart valves are damaged due to rheumatic fever and the resultant inflammation). In the case of aortic valve disease due to severe aortic valve stenosis, there is markedly restricted opening of the valve and the heart needs to pump harder in order to eject sufficient blood through the narrowed valve. In the long run, heart failure can ensue.
Cardiomyopathy refers to diseases of the heart muscle. Cardiomyopathy is a condition where the heart muscle becomes enlarged, thick or rigid. The heart muscle may also be replaced with scar tissue. Types of cardiomyopathy include hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia and peripartum cardiomyopathy.
Diabetes mellitus, obesity, older age and overweight are commonly associated with heart failure. Other conditions that cause heart failure include abnormal heart rhythm, myocarditis (infections and inflammation of the heart muscle), congenital heart disease, drugs (alcohol, cocaine, therapeutic drugs such as doxorubicin), anaemia, hyperthyroidism and thiamine deficiency. Conditions that cause predominantly right heart failure include chronic lung disease due to long standing history of smoking, pulmonary hypertension (a type of high blood pressure that affects the arteries in our lungs and the right side of our heart) and pulmonary embolism (blockage of artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream).
Heart failure and its aetiology can be assessed by echocardiogram and magnetic resonance imaging of the heart and radionuclide myocardial perfusion imaging. CT coronary angiogram is useful to assess the presence of coronary artery disease non-invasively. Invasive coronary angiography can ultimately assess the presence or absence of significant coronary artery disease. Prompt treatment with medications, fluid restriction and low salt diet are vital in the treatment of heart failure. Coronary revascularization with coronary artery stenting or coronary artery bypass surgery is important if the heart failure is due to significant coronary artery disease and the heart muscles are still viable (alive). In addition, cardiovascular risk factors include high blood pressure, diabetes mellitus and high cholesterol level should be treated with lifestyle modification includes regular exercise and diet control. Adherence to medication is also essential to prevent fluid overload and recurrence of symptoms of heart failure. Automated implantable cardioverter defibrillator and cardiac resynchronisation therapy devices can be advocated in certain group of patients. Prevention of heart failure is better than cure. Therefore, proper health check of a person’s heart is essential to prevent the development of disease that causes heart failure.
Dr Wong Siong Sung
Senior Consultant Cardiologist
Medical Director of Healthy Heart Specialist Centre
Medical Director of Somerset Imaging Centre
MD, FAHA, FRCP (Edinburgh), FASNC, FAMS (Cardiology)
MRCP (UK), MRCPS (Glasgow), DCBCCT (USA), DCBNC (USA)