Heart Conditions
 
 
Cardiovascular disease is a generic term used to refer to any abnormality of the heart and/or the vascular system. These abnormalities may be caused by degenerative changes in the blood vessels, extraneous infections, or congenital defects. The more common types of cardiovascular disease include:
 
Atherothrombosis
 
Atherothrombosis (AT) is the underlying condition responsible for the greatest number of deaths in Singapore. AT causes heart attack, stroke, and peripheral artery disease (narrowing or obstruction caused by cholesterol affecting the arteries that supply blood flow to the legs).
 
The risk factors of AT are high blood pressure, cholesterol, and obesity. AT is the common link between all these diseases and risk factors, however, this silent killer goes largely unrecognised by the man on the street.
 
Atherothrombosis is a global disease, meaning that if a person has atherothrombosis affecting their heart (e.g. if they have had a previous heart attack), they are likely to have atherothrombosis affecting their brain and limbs, predisposing them to a stroke or peripheral artery disease.
 
AT starts when deposits such as cholesterol builds up in the walls of our arteries. Over time these deposits, known as plaque, restricts the flow of oxygen-rich blood throughout the body. This is a gradual process, which takes place over years.
 
As blood flows over the plaque, stress forces are exerted on the plaque surface. Eventually, the plaque may rupture. This acute event causes platelets in the blood to stick to the plaque and to other platelets forming a blood clot.
 
This clot (or thrombus) can limit or completely stop the flow of blood to part of the heart or brain, giving rise to a heart attack or stroke. That’s why it’s critical to treat atherothrombosis and reduce the risk of a life-threatening clot forming.
 
Heart Patients – Being AT Aware
 
Heart patients need to be aware that, if they have suffered from a heart attack, they also have a condition that may affect the whole body including the brain and legs as well.
 
Understanding this, patients can take active steps to reduce their AT risk factors, such as seeking appropriate treatment and making lifestyle changes. Statistics show that heart attack patients are not only 5 times more likely to suffer a repeat heart attack than the general population, but their risk of having a stroke is tripled. Heart attack patients are also at an increased risk of developing PAD – peripheral arterial disease.
 
Statistics from the Reach Registry – a worldwide survey of atherothrombosis patients – suggest that on average, around one in eight outpatients with stable atherothrombosis, will die, have a heart attack or stroke, or be hospitalised for a complication arising from atherothrombosis within a year.
 
How many heart patients realise these risks of recurring events exist? How many of these patients are aware they can reduce their risk through lifestyle changes and medication?
 
Only with increased awareness of the prevalence, prevention and treatment of AT – among both the general public and the medical profession – can we begin to take the first steps to win the battle against the silent killer that is atherothrombosis.
 
Reducing your AT risk

  • Regular gentle exercise
  • Eating healthily
  • Maintain an ideal weight
  • Avoid excessive alcohol intake
  • Go for screening
  • Prevent stress
  • Avoid smoking
 
It is vital to adequately control various risk factors, including the need to use medications to control diabetes, hypertension and high cholesterol, as well as medications to reduce stickiness of platelets such as aspirin and clopidogrel
 
Atherosclerosis
 
What is atherosclerosis and how does it develop?
 
Watch this animation to better understand this medical condition.
 
Atherosclerosis, commonly referred to as the “hardening of the arteries”, is a progressive disease which causes a person’s arteries to become narrow and their walls to lose elasticity due to the accumulation of deposits on the inner lining of these blood vessels.
 
In patients with this condition, substances such as cholesterol, fats, calcium, and fibrin (clotting factors in the blood) build up into plaque and narrow the openings of the affected arteries. As atherosclerosis worsens, it may lead to the blood vessels becoming so narrow as to decrease blood flow.
 
The exact mechanism underlying the development and progression of atherosclerosis is not known, but many scientists believe that it is sparked off by damage to the endothelium, the innermost lining of blood vessels. Such damage may be caused by a variety of factors including elevated blood lipid levels, high blood pressure (hypertension), and smoking.
 
As a result of damage to the endothelium, cellular debris, fibrin, cholesterol, and other fatty substances deposit on the walls of arteries. The affected arterial walls become more permeable to low-density lipoprotein cholesterol, also known as “LDL” or “bad” cholesterol. Once the “bad” cholesterol is oxidized, it stimulates the endothelial cells to secrete chemical substances.
 
This leads to further accumulation of deposits on the walls of arteries at the site of the plaque. As the atherosclerotic lesion develops, a lipid core builds up, damaging the arterial walls and increasing the risk of blood clot formation (thrombosis). The innermost layer of the affected arteries becomes thickened, with a corollary decrease in blood flow in that vessel.
 
Atherosclerosis can develop in any of the arteries in the body. When it occurs in the coronary arteries supplying blood to the heart, the patient is said to have coronary heart disease. The most common symptom of this condition is a radiating chest pain known as angina pectoris, or angina for short. Should coronary arteries already narrowed by atherosclerosis become completely blocked by a blood clot (thrombus), a heart attack ensues.
 
Coronary Heart Disease and Angina
 
Coronary heart disease is the most common type of heart disease in many industrialised countries. It arises from the narrowing of the coronary arteries, resulting in reduced blood flow and thus oxygen supply to the heart muscle.
 
Such narrowing of the coronary arteries is typically caused by atherosclerosis. Other contributory factors include spasms in the coronary vessels, diabetes, high blood cholesterol, high blood pressure, adverse physical reactions to mental stress, and heavy smoking.
 
The primary symptom of coronary heart disease is angina, a squeezing chest pain which may spread to the neck, jaw, abdomen, and upper left part of the body. The pain is a signal that the heart is not receiving sufficient blood and oxygen. Angina may present itself in a number of different ways.
 
For instance, patients with “silent” angina tend to experience no physical discomfort or pain. Angina may also be stable or unstable.
 
Stable angina refers to chest pain and/or discomfort which occurs in a regular or predictable pattern (for instance, whenever the patient walks up a flight of stairs) and which is usually relieved by rest.
 
In contrast, unstable angina, which is more serious, is discomfort that occurs without warning. The patient may experience sudden sharp pain even with little or no physical exertion, or even without having any prior symptoms of coronary heart disease.
 
Heart Attack
 
Heart attack, or myocardial infarction, occurs when the interior passage of a coronary artery, usually already narrowed by atherosclerosis, becomes completely blocked due to a blood clot or arterial plaque. Part of the heart muscle dies in the process due to oxygen deprivation, giving rise to the crushing chest pain characteristic of a heart attack.
 
Here’s a simple animation to show you how it happens.
 
While chest pain is the most common symptom of a heart attack, this life-threatening event may present itself in diverse ways among different patients. For instance, in diabetic patients, heart attacks are generally silent without any accompanying chest pain.
 
Some of the other physical symptoms which a heart attack victim may complain of are:

  • A choking sensation
  • Heart burn/indigestion
  • Nausea
  • Shortness of breath
  • Sweating
  • Palpitations
  • Giddiness
 
Caregivers and family members of cardiac patients should also be alert to a sudden and complete loss of responsiveness on the patient’s part as well as a cessation of signs of circulation, as these may likewise be warning signs of a heart attack.
 
The timing of treatment is critical for heart attack victims because their chances of survival decrease rapidly with every passing minute. When the heart stops beating, brain damage sets in after 3 minutes, and death is virtually certain if no resuscitation is given to the victim within the first 10 minutes. In this respect, knowledge of cardiopulmonary resuscitation (CPR) is a valuable asset, especially where caregivers and family members of patients at high risk of having a heart attack are concerned.
 
Stroke
 
Stroke, or brain attack, occurs when the brain is damaged due to a disruption of blood supply. The brain requires a constant supply of energy to perform its functions. If blood flow to the brain is restricted or cut off at any point, the brain suffers injury. Should the disruption continue for more than several minutes, the brain cells may become permanently damaged and tissue in the affected region may die.
 
The resultant loss or alteration of bodily functions due to an inadequate supply of blood to one or several parts of the brain is called a stroke.
 
There are two main types of stroke – ischaemic and haemorrhagic.
 
In ischaemic stroke, which accounts for approximately 80% of all strokes, blood supply to the brain is disrupted due to an obstruction in one or more blood vessels. Such obstruction often occurs in one of the two carotid arteries in the neck carrying oxygenated blood from the heart to the brain.
 
A blood clot may also develop at other locations in the body and travel through the bloodstream until it lodges itself in a blood vessel which is already narrowed by a pre-existing condition such as atherosclerosis. About 10% of ischaemic strokes are preceded by transient ischaemic attacks (TIAs). These are mini strokes arising from a temporary interruption of blood supply to the brain. They usually last for only a few minutes, and most of their symptoms disappear completely within 24 hours.
 
Less common is haemorrhagic stroke which occurs when one or more blood vessels in the brain rupture. Blood leaking from the ruptured vessel compresses other vessels nearby and eventually forms into a clot, cutting off blood supply to the surrounding brain tissue. In general, a haemorrhagic stroke tends to affect larger areas of the brain than does an ischaemic stroke, resulting in greater impairment of the victim’s bodily functions.
 
The symptoms of both types of stroke are similar, although those of haemorrhagic stroke may be more sudden and severe.
 
Common symptoms include:

  • Weakness and/or numbness on one side of the body
  • Slurred speech;
  • Loss of vision in either or both eyes
  • Giddiness
  • A sudden, severe headache
  • Drowsiness, followed in some cases by coma
  • Unsteadiness and loss of muscular coordination
 
The symptoms experienced by a stroke victim vary depending on the size and location of the blood clot which precipitates the stroke. For some patients, the symptoms may occur suddenly; for others, they may develop slowly over the course of several hours or even a few days.
 
The main risk factors for stroke are:

  • Age
  • High blood pressure (hypertension)
  • High levels of LDL/“bad” cholesterol
  • Diabetes mellitus
  • Smoking, including passive smoking
  • Excessive alcohol consumption
 
All of these factors contribute to atherosclerosis (hardening of the arteries), which in turn increases the likelihood of an ischaemic stroke. Similarly, these risk factors may cause blood vessels to weaken, resulting in a haemorrhagic stroke.
 
Fortunately, although some of the risk factors for stroke (for instance, age) cannot be altered, the majority can be reduced by adopting healthy living practices such as:

  • Monitoring your blood pressure regularly and seeking prompt medical treatment if you are found to be hypertensive
  • Having your blood sugar and cholesterol levels tested periodically
  • Maintaining a healthy body weight
  • Eating a healthy, well-balanced diet
  • Incorporating regular exercise into your daily routine
  • If you are a smoker, giving up smoking
  • Avoiding or stopping drug and alcohol abuse
 
Taken together, these measures can go a long way in preventing stroke.
 
Heart Failure
 
Heart failure, also referred to as congestive heart failure, occurs when the heart loses its ability to pump blood within the body effectively. As a result, there is relative stagnation and backward pooling of blood in vital organs and vessels.
 
One of the early symptoms of heart failure is shortness of breath, especially during exercise. As the patient’s condition worsens, congestion in the lungs and breathing difficulties develop. Some patients may also notice a “wet” sound when they are breathing.
 
This is caused by the build-up of fluid in the air sacs of the lungs. At the same time, the accumulation of fluid in organs such as the liver and intestines will cause the patient to experience abdominal pain and loss of appetite. Distension of the veins in the neck may also occur due to the pooling of blood in these vessels.
 
At a more severe stage of heart failure, the patient’s kidneys may begin to fail due to inadequate blood supply. This results in further accumulation of water and waste products in the body, thus aggravating the swelling (oedema) of the body.
 
In particular, fluid is likely to build up in the patient’s legs and ankles due to the effect of gravity. Such fluid will be reabsorbed into the bloodstream when the patient lies down, flooding his lungs and aggravating his breathlessness. The patient may even need to lie propped up or stand simply to breathe.
 
Heart failure can develop as a result of:

  • Coronary heart disease
  • A previous heart attack
  • High blood pressure;
  • Damage to the heart valves (for instance, due to rheumatic fever or other infections);
  • Cardiomyopathy (a disease of the heart muscle which causes it to become progressively weaker and gradually lose its ability to pump blood effectively).
 
Congenital Heart Disease
 
Congenital heart disease comprises a wide spectrum of heart defects which may be present at the time of a person’s birth.
 
The most common type of congenital defect is a hole in the heart. This may occur between the two atria (an atrial septal defect) or between the two ventricles (a ventricular septal defect). Both conditions typically present themselves in the form of heart murmurs which are abnormal sounds produced by turbulence in the flow of blood through the heart. A ventricular septal defect is generally more serious than an atrial septal defect and, unless the hole in question is very tiny, must be repaired.
 
Other examples of congenital heart disease include aortic stenosis and Tetralogy of Fallot. In patients with the former condition, the aortic valve (i.e. the valve which separates the left ventricle from the aorta) is unusually narrow. The left ventricle therefore has to work harder to pump blood through the narrowed valve. Where the constriction is severe, the supply of oxygenated blood to other parts of the body may be considerably reduced.
 
As for Tetralogy of Fallot, it is a condition arising from several different malformations of the heart, namely: the narrowing of the pulmonary valve (pulmonary stenosis); a hole in the wall between the ventricles (a ventricular septal defect); and the “overriding” by the aorta of the hole between the ventricles. As a result, the aorta receives blood from both the left and right ventricles.
 
This in turn means that the blood which is pumped out of the heart for distribution to other organs is a mixture of oxygenated and deoxygenated blood, and not oxygenated blood alone. Tetralogy of Fallot is usually detected via the characteristic bluish tinge of affected infants’ skin, a symptom arising from an insufficient supply of oxygen-rich blood.
 
Arrhythmias
 
Arrhythmias are abnormal heart rhythms which are produced when the natural electrical conduction system of the heart malfunctions. Not all arrhythmias pose health risks. For instance, a person may have a persistent minor arrhythmia which is in fact normal for his heart. Similarly, a temporary arrhythmia caused by alcohol, caffeine, or insomnia is not usually a cause for concern.
 
Arrhythmias are generally classified into two groups:
1. Bradycardia, an abnormally slow heart rhythm
2. Tachycardia, an abnormally fast heart rhythm
 
Bradycardia
 
Patients with bradycardia generally have a heart rate of only about 40 to 60 beats per minute. They tend to experience fatigue, dizziness, and episodes of fainting as their hearts do not pump enough blood to supply their brains and other vital organs with sufficient oxygen.
 
In contrast, patients with tachycardia have abnormally rapid heart rhythms, usually of more than 100 beats per minute. The main symptoms of this condition are similar to those associated with bradycardia.
 
Tachycardia
 
Tachycardia may arise in either the atria or the ventricles. The former occurs when the atria become enlarged by hypertension, inflamed, or damaged by coronary heart disease. The resultant rapid irregular beating of the atria is known as atrial fibrillation or atrial flutter. If atrial fibrillation remains untreated, there is an increased risk of stroke. Ventricular tachycardia is much more dangerous in comparison. When the ventricles beat too rapidly, the heart does not have enough time to fill with blood in between beats, causing blood pressure to drop. Ventricular tachycardia may worsen and turn into ventricular fibrillation, a potentially fatal condition in which the ventricles merely quiver and do not pump any blood at all. If untreated, ventricular fibrillation will lead to immediate loss of consciousness and death.
 
Sudden Cardiac Death
 
Sudden cardiac death (SCD) is the natural death from cardiac causes, heralded by abrupt loss of consciousness within one hour of the onset of acute symptoms.
 
How is sudden cardiac death different from a heart attack?
 
SCD is one of the ways in which a heart attack presents. It is thought that in fact about half of heart attack victims present with SCD. The other victims present with the more familiar symptoms of chest pain, chest tightness, breathlessness, cold sweats, nausea etc.
 
What are the symptoms of sudden cardiac arrest?
 
SCD can be preceded by the more classical symptoms of a heart attack which then rapidly progress into abrupt collapse and loss of consciousness. However, premonitory symptoms may be absent or may be nonspecific.
 
What are the risk factors of sudden cardiac arrest?
 
About 80% of SCD is due to coronary heart disease (CHD). Since this is a condition whose incidence increases with age. SCD is more likely to be due to CHD in older patients. SCD is particularly likely to occur the more severe the CHD, the greater the number of coronary arteries affected and especially where the main trunk of the left coronary artery is obstructed (sometimes called the “widow maker’s disease). SCD risk also is higher in those who have previously had a heart attack resulting in extensive heart muscle damage and heart failure.
 
Since CHD is the commonest underlying cause of SCD the risk factors would be those which cause atherosclerosis, the disease process which results in CHD. These include age, smoking, high BP, high cholesterol, diabetes, obesity, sedentary lifestyle, stress as well as family history.
 
In younger patients in whom CHD is less frequent other causes which may have a genetic basis may be present. These conditions include abnormalities of the electrical system of the heart eg the “long QT interval syndromes”, Brugada syndrome ; abnormalities of the heart muscle eg hypertrophic cardiomyopathy, various forms of congenital heart disease (“hole-in-the-heart”, “blue babies”), various types of heart valve disease.
 
Can sudden cardiac arrest be prevented? Should I be going for tests to find out if I have a heart defect that will eventually lead to sudden cardiac death?
 
The risk of SCD can be reduced by reducing the risk of CHD, screening for CHD risk factors and effective control of these factors e.g. high BP, high cholesterol etc. In those with known CHD various types of tests can be conducted to identify those at higher risk of heart attack and SCD. These tests include ECG, exercise or other types of stress tests, echocardiography, imaging techniques e.g. CT scans, isotope scans, coronary angiography.
 
Those at higher risk may be treated with medications, angioplasty, pacemakers or implantable defibrillators.
 
In younger individuals those with a family history of SCD or other types of heart disease affecting younger members of the family may be screened by a doctor and referred if there are suggestive signs e.g. an abnormal ECG.
 
Individuals planning to participate in strenuous exercise should have a medical examination which may include an ECG, a stress test (e.g. a treadmill test), and other types of cardiac examination.
 
What causes sudden cardiac death?
 
The immediate cause of SCD is often a sudden development of an abnormal rhythm of the heart called ventricular fibrillation (VF) in which there is chaotic electrical activity without mechanical contraction so that there is rapid cessation of blood circulation. VF can be preceded by ventricular tachycardia (VT) where there is a rapid heart rate eg 200 beats per minute but blood pressure may be very low.
 
What is the treatment for sudden cardiac death?
 
Since VF is usually present, the most effective treatment is the use of an electrical medical device called a defibrillator which delivers an electrical shock through the chest. However since a defibrillator may not be immediately available, CPR (cardiopulmonary resuscitation) should be immediately initiated to maintain circulation and ventilation until medical help arrives. Many ambulances now carry defibrillators and are manned by personnel trained in CPR and defibrillation.
 
All individuals especially those who are likely to witness SCD including family members of patients who have CHD or other types of heart disease with increased risk of SCD should be encouraged to learn CPR. Laypersons can also be trained to use a semi-automatic defibrillator. Many airlines now have these devices on board their aircraft. It would be advisable for those organising sports events to check whether the medical services on standby have this device.
 
Will a GP be able to tell if I am suffering from sudden cardiac arrest? How?
 
SCD is often quite obvious because the victim collapses, rapidly loses consciousness, and eventually becomes pulseless when the heart stops. SCD can occur anywhere. Diagnosis cannot wait for a doctor to be called unless he or she is fortuitously present.
 
Should I suffer from sudden cardiac arrest, what is the “golden period” in which I should be resuscitated and treated in order to have a quality life, post SCD?
 
Resuscitation of SCD or any other form of cardiopulmonary arrest should be initiated within 4 minutes, as any delay beyond this period may result in permanent brain as well as cardiac damage. The chances of effective resuscitation also rapidly decrease the longer the delay before it is initiated.