Brief overview
- Symptoms: Sudden loss of consciousness, no breathing, no pulse, dilated pupils; warning signs in advance such as a feeling of pressure or tightness in the chest, dizziness and fainting, shortness of breath and water retention, cardiac arrhythmia
- Causes and risk factors: Mostly sudden ventricular fibrillation, usually caused by (undiagnosed) heart disease, triggers include acute infarction, physical exertion (such as sports), emotional stress, medications or drugs
- Diagnosis: Acute absence of respiration and pulse, ECG or AED detects ventricular fibrillation; in advance, heart disease can be detected (preventively) by physical examination, stress or long-term ECG, ultrasound, myocardial scintigraphy and other examinations
- Treatment: acute immediate cardiopulmonary resuscitation, ideally support with AED (automated external defibrillator)
- Prognosis: Without cardiopulmonary resuscitation, the victim dies; prognosis with successful resuscitation depends on the time between cardiac arrest and resuscitation
What is sudden cardiac death?
Sudden cardiac death (secondary death) is one of the most common causes of death, according to experts. It is estimated that in Europe (and North America) sudden cardiac death accounts for 50 to 100 cases out of every 1000 deaths.
In the absolute majority of cases, this sudden cardiac arrest can be attributed to severe heart disease. In many cases, this heart disease is already noticeable in advance. Sudden cardiac death could therefore be prevented in numerous cases by timely clarification and diagnosis.
Medically, it is an unexpected cardiovascular failure that, if left untreated, leads to natural death within seconds to 24 hours at the latest after the first symptoms.
However, sudden cardiac death very rarely affects even perfectly healthy and young people without significant symptoms. Sometimes a genetic disease is discovered afterwards, which favors severe cardiac arrhythmias. However, a clear cause cannot be found in every case.
What are the symptoms or signs?
Sudden cardiac death is initially manifested by a sudden loss of consciousness of the affected person. Within a short time, spontaneous breathing also stops. The unconsciousness is caused by a circulatory arrest (sudden cardiac arrest): The heart no longer pumps sufficient blood to the brain and other organs.
The resulting lack of oxygen (hypoxia) causes brain function to fail. Without oxygen, the brain cells die after only a few minutes. The affected person’s pulse is no longer palpable and his pupils dilate. If this condition is not corrected within a few minutes, death (sudden cardiac death) occurs after a short time.
Often sudden cardiac death occurs without any warning. However, according to the Oregon Sudden Unexpected Death Study, secondary death is preceded by warning signs in more than half of cases. These include symptoms that may indicate possible damage to the heart.
- Feeling of pressure or tightness in the left chest, especially during exertion: Possible indication of a chronic circulatory disorder in coronary heart disease or of a heart attack
- Dizziness or fainting: sometimes triggered by cardiac arrhythmia causing a slight lack of oxygen to the brain
- Shortness of breath and water retention (edema): Typical of heart failure (cardiac insufficiency).
- Pronounced cardiac arrhythmias: A pulse that is too fast (tachycardia) or too slow (bradycardia) are possible signs of a dangerous cardiac arrhythmia that is developing.
These symptoms do not necessarily indicate impending sudden cardiac death. In particular heart rhythm disturbances occur also with perfectly healthy humans and are in many cases harmless.
Who notices however such symptoms with itself, should let the complaints clarify medically. This can often prevent sudden cardiac death in an emergency.
What are the causes of sudden cardiac death?
In ventricular fibrillation, the electrical excitation of the heart is completely uncoordinated and chaotic. Due to the asynchronous electrical activity, the heart muscle no longer contracts in conformity with the norm, but twitches at a high frequency, but without any appreciable pumping action.
Without sufficient pumping function of the heart, the organs are no longer supplied with blood and thus with vital oxygen. In the brain, the lack of oxygen (hypoxia) causes a loss of function after only a few seconds, rendering the affected person unconscious. Without brain function, spontaneous breathing stops after about one minute, which further aggravates the oxygen deficiency.
In the absolute majority of cases, sudden cardiac death can be attributed to serious heart disease.
- Very common (about 80 percent of cases): Coronary heart disease (CHD).
- Common (10 to 15 percent of cases): Diseases of the heart muscle (cardiomyopathies, myocarditis) or structural defects (heart valve damage).
Researchers suspect that in addition to these predisposing conditions, a specific trigger is required for sudden cardiac death to occur. For example, scientists count the following situations and substances as potential triggers for sudden cardiac death when there is an underlying disease of the heart:
- Acute circulatory disturbance of the coronary arteries (“myocardial infarction”), usually with pre-existing coronary artery disease
- Pronounced physical exertion such as intensive sports
- Emotional stress situations
- Drugs that influence the conduction of impulses in the heart (such as so-called QT time-prolonging drugs)
- Drugs such as alcohol, cocaine and amphetamines
- Shifts in blood salts (electrolyte imbalances)
In principle, sudden cardiac death is possible in all situations, occurring, for example, during sleep, has already occurred in soccer players on the field, or hits people “out of the blue” in the middle of their walk through the pedestrian zone, for example.
Investigations and diagnosis
In an acute emergency situation, sudden cardiac death can only be prevented by an immediate and correct diagnosis of the underlying cardiac arrhythmia.
Laypersons trained in first aid or cardiopulmonary resuscitation can recognize an emergency situation by the absence of breathing and a pulse. For example, if the unconscious person does not respond to a pain stimulus (such as rubbing the sternum with a fist), cardiopulmonary resuscitation should be started (see below). An AED, an automated external defibrillator, which can be found in many public places for laypersons, also diagnoses ventricular fibrillation.
However, conditions that promote sudden cardiac death can often be diagnosed before such a life-threatening event occurs.
In particular, if someone already has symptoms that indicate heart disease and is thus potentially at risk of sudden cardiac death, medical clarification should be sought urgently. This can help diagnose and treat serious heart disease before it becomes serious.
Doctor-patient consultation
The first point of contact for symptoms that may indicate heart disease is a general practitioner or a specialist in internal medicine and cardiology (cardiologist).
- Do you notice a feeling of pressure or tightness in your chest when you exert yourself physically?
- Does this feeling radiate to other areas of your body, for example, your neck, jaw, or left arm?
- Have there been any recent situations in which you felt dizzy without a specific cause?
- Have you fainted recently?
- Have you noticed water retention on you, for example on your ankles?
- Do you experience shortness of breath when you exert yourself physically, for example when climbing stairs?
- Have you noticed “heart palpitations”?
Physical examination
During the physical examination, the doctor will get a first impression of your heart function by feeling your pulse and listening to your heart with his stethoscope (auscultation). In this way, he determines whether the heart is beating regularly and at the correct rate (heart rate), as well as whether any abnormal heart murmurs caused by structural heart problems (such as diseased heart valves) are noticeable.
In addition, water retention (edema) can be detected during the physical examination. Edema in the feet and legs in particular are possible signs of heart failure.
Further examinations
Depending on the results of the medical history and physical examination, the attending physician will order other examinations for further clarification. The physician will almost always perform an electrocardiogram (ECG). This can detect a variety of pathological changes in the heart that promote sudden cardiac death.
Since a normal ECG records only a few heartbeats, in some cases a recording over 24 hours is necessary (long-term ECG). This is particularly useful when there is a question of only occasionally occurring cardiac arrhythmias.
Very often, the physician also orders an ultrasound examination of the heart (UKG, echocardiography). This is particularly useful for detecting structural heart diseases such as a thickened heart wall, an enlarged heart or damage to the heart valves. An X-ray examination of the chest (chest X-ray) is also useful in order to assess any pathological changes in the heart and lungs.
If there are indications of coronary heart disease, further examinations may be indicated, for example cardiac catheterization (= coronary angiography), stress echocardiography or further imaging such as myocardial scintigraphy (nuclear medical examination of the heart muscle). Sudden cardiac death is by far the most commonly caused by coronary artery disease (CAD).
Treatment
Despite the many possible causes, ultimately a serious cardiac arrhythmia is always the immediate trigger of sudden cardiac death. In most cases, this is a so-called ventricular fibrillation, more rarely slow (bradycardic) cardiac arrhythmia or sudden cardiac arrest (asystole).
Impending sudden cardiac death is an absolute emergency that requires immediate correct diagnosis and immediate countermeasures. Otherwise, the affected person will die within a few minutes. First aid significantly increases the chances of survival.
The following procedure is recommended for first responders when a person suddenly collapses unconscious and sudden cardiac death is imminent:
- Make an emergency call and ask bystanders for help.
- If there is no pulse and no breathing, start cardiopulmonary resuscitation immediately: Alternate 30 chest compressions over the sternum and two mouth-to-mouth or mouth-to-nose resuscitations. If two or more first responders are on scene, they should alternate after each 30:2 cycle to avoid fatigue.
- If available, first responders should use an automated external defibrillator (AED). These are now placed in many public places (banks, city halls et cetera) or on public transportation (subway stations, trains et cetera). The devices are very easy to attach and guide the helper step by step through the necessary measures with an announcement. After the electrodes are attached, the AED independently analyzes the heart rhythm and only triggers an electric shock if a defibrillatable cardiac arrhythmia is present (ventricular fibrillation, pulseless ventricular tachycardia). The rapid use of a defibrillator is often life-saving!
What the emergency physician does
First, an ECG is performed at the scene to analyze the heart rhythm during continuous cardiopulmonary resuscitation. If defibrillation is not sufficient or if there is a cardiac arrhythmia that cannot be defibrillated (asystole, pulseless electrical activity), the emergency physician usually also tries to restore a normal heart rhythm with drugs such as adrenaline.
Sudden cardiac death can often be prevented by the immediate intervention of trained rescuers.
Course of the disease and prognosis
In cases of impending sudden cardiac death, the course of the disease and the prognosis are decisively influenced by how quickly appropriate countermeasures are taken after the onset of cardiovascular arrest. Circulatory arrest causes death within a few minutes without treatment due to irreversible damage to the brain. If too much time elapses between the circulatory arrest and a successful resuscitation, severe brain damage usually remains, which may turn the affected person into a nursing case.
Prevention
First, symptoms that indicate potential heart disease should not be ignored. Through simple examinations, threatening heart diseases, which are often responsible for sudden cardiac death, can be diagnosed and treated at an early stage.
In acute cases, the chances of surviving sudden cardiac death increase if a defibrillator is quickly at hand and used as soon as possible, along with proper cardiopulmonary resuscitation. Both are learned in first aid courses, which must be repeated regularly (at least every two to three years, according to experts). Only then is it possible to effectively help someone threatened with sudden cardiac death in an emergency.
For friends and relatives of people who die of sudden cardiac death, the event is usually shocking – but since there are possible family causes (genetic diseases), after the sudden cardiac death of a relative from an unknown cause, one should consider screening all family members for such a disease as a precaution.
