A few days ago, September 29th we celebrated world heart day which is a day set aside to create awareness of the various heart conditions and ways to prevent them. Still, in the spirit of that celebration, my today's discussion will be a very important topic which is among the leading causes of sudden death globally.
Cardiac arrest is a condition where the heart suddenly stops beating due to a serious alteration in the electrical activities of the heart.
By Myupchar, CC BY-SA 4.0, Wikimedia
The heart works in a very coordinated manner. It generates its electrical impulses from a node in the heart called the Sinoatrial node (SA node). This generated impulse is coordinated sequentially and orderly through the heart and controls the heartbeat, rate, and rhythm.
When there is any disturbance in this orderly flow of the electrical impulses through the heart, the heart starts beating irregularly, too fast, or too slow. This is described in medical terms as heart arrhythmia.
So, in cardiac arrest, there is a disturbance in the electrical activities of the heart, which causes the lower chambers of the heart (the ventricles ) to beat in an erratic, rapid, and uncoordinated manner. This type of heart rate is ineffective and therefore cannot produce a pulse and an adequate contraction and relaxation of the heart that can pump blood to the vital organs of the body like the brain.
This rapid beating of the lower chambers of the heart is described in medical terms as ventricular tachycardia. The severe form of it is called ventricular fibrillation. If there is no urgent intervention at this point, the outcome of this rapid twitching of the ventricles is the heart's inability to pump blood to the vital organs of the body which results in loss of consciousness and death - CARDIAC ARREST!
Cardiac arrest can also result from the failure of the conducting tissues of the heart to conduct the cardiac impulses which result in absent electrical activity in the lower chambers of the heart. This is referred to as asystole.
In pulseless electrical activity (PEA), the electrical activities of the heart are intact but the heart cannot produce an effective cardiac out put to supply to the vital organs. This usually has a bad outcome and can be due to severe heart conditions like the rupture of the heart.
The commonest occurrence in cardiac arrest is the ventricular tachycardia and ventricular fibrillation. Asystole and pulseless electrical activity occur less commonly.
By CERTAcademy - Own work, CC BY-SA 4.0, Wikimedia
This reminds me of a childhood tragic experience, the day I lost my very close uncle to cardiac arrest. My uncle who was apparently well, traveled from Lagos to our hometown with his family for the Christmas celebration of that year. On their arrival, he was warmly welcomed and there was a lot to eat and drink that night. He was served his delicious meal and everyone was in a happy mood.
However, the happy mood was brought to an abrupt halt when in between the meal, he suddenly held his chest complaining of severe chest pain. Everyone started running helter-skelter trying to find a solution. There, he suddenly slumped, and before he was rushed to the hospital that night, he gave up the host. The once happy mood was turned into a sad one, caused by CARDIAC ARREST!
The incident was painful, but the most painful now each time I remember it was that he could have been saved if any of us knew about cardiopulmonary resuscitation (CPR). I was a teen then and no one there had an idea of what was happening and how he could have been saved.
So in the later part of this discussion, I will talk about CPR and how anybody can perform it, whether you are trained or untrained.
By Scienctific Animations, CC BY-SA 4.0, Wikimedia
WHY DO WE NEED TO KNOW ABOUT CARDIAC ARREST
According to the Centre for Disease Control (CDC);
In 2015, approximately 357,000 people experienced out-of-hospital cardiac arrest (OHCA) in the United States.
Approximately 209,000 people are treated for in-hospital cardiac arrest (IHCA) each year.
Approximately 70%–90% of individuals with OHCA die before reaching the hospital.
Those who eventually survive cardiac arrest suffer serious brain damage and other major health challenges.
CAUSES OF CARDIAC ARREST
So, let us look at those conditions that alter the electrical activities of the heart and cause cardiac arrest.
The chief cause of cardiac arrest, which contributes to about 85% of the causes is Coronary artery disease (CAD).
Let us dig deep into the major culprit of this nightmare.
CORONARY ARTERY DISEASE
This occurs due to the narrowing or blockage of the lumen of the blood vessels that supply the heart (coronary artery). This narrowing is caused by the deposition of fats, cholesterol, and other substances like calcium, fibrin, etc in the wall of the coronary artery. These deposits are referred to as plaques.
By Myupchar, CC BY-SA 4.0, Wikimedia
When these plaques deposit on the wall of the coronary artery, any injury on it or its rupture will lead to the build-up of more substances there and it keeps building up till the lumen of the vessel is either partially or totally occluded. This leads to the shortage of blood supply to the heart muscles which results in chest pain described in medical terms as angina pectoris.
This angina can be either stable or unstable angina. There is also a third class called prinzmetal angina.
Stable angina is characterized by central chest pain or discomfort that occurs during activities or stress and is relieved by rest. In these patients, the size of the vessel occlusion is relatively constant. Though there is reduced blood supply to the heart, it is not blocked yet and the lumen is not getting narrower.
For those with unstable angina, the plaque is building up more and the lumen is getting narrower. So they experience rapidly worsening chest pain that occurs on any little activity or even at rest. However, at this point, the heart muscle cells have not started dying.
As this shortage of blood supply persists, the heart muscle cells will start dying due to a lack of blood, oxygen, and nutrient. This stage is described as Myocardial Infarction (MI) and can be either a Non-ST Elevated Myocardial Infarction (NSTEMI) when the coronary vessel lumen is still partially occluded, or an ST Elevated Myocardial Infarction (STEMI) when the coronary vessel lumen is totally occluded.
By United States: Centers for Diseases Control and Prevention, Public Domain, Wikimedia
These patients experience severe central, squeezing, heavy, crushing, and excruciating chest pain. The pain can radiate to other parts of the body like the left arm, neck, back, etc. They may also have nausea, vomiting, and excessive sweating. They are anxious and weak and usually have a feeling of impending doom.
Angina can be precipitated by some activities like heavy meals, extremes of emotions, exposure to cold, stressful activities, etc.
RISK FACTORS
What are the risk factors that can predispose someone to this coronary artery disease?
Here, there are risk factors that are non-modifiable because the patient can't do much to change them. These risk factors include:
- Gender: The male gender is at more increased risk of having coronary artery disease than the female gender.
- Age: This disease occurs with increasing age and as one advance in age, his risk increases as well.
- Positive family history: Those who have immediate family members like a father, mother, or siblings who develop coronary artery disease are at more increased risk than those who don't have anyone in their family with the disease.
- Genetics and Race also play a vital role. The incidence of coronary artery disease has been found more in Caucasians. However, with the dietary shift in Africa and the rising incidence of obesity, hypertension, and diabetes, the incidence of coronary artery disease is also rising in Africa.
The second group of risk factors for coronary artery disease is the modifiable risk factors. These are the risk factors that anyone can avoid and stay away from this disease.
The most important of them here are; high blood pressure, high concentration of fats in the blood (hyperlipidemia), smoking, obesity, and diabetes mellitus. Psychological factors like stress, depression, and anxiety are also risk factors. Other risk factors include; a sedentary lifestyle, excessive alcohol consumption, use of some drugs like NSAIDs, etc.
INVESTIGATIONS
The investigations that can be done for patients with coronary artery disease are;
Electrocardiogram (rest and exercise ECG) which shows the electrical activities of the heart and helps to make a diagnosis.
By Various - Cureus, CC BY 4.0, Wikimedia
Another investigation is the plasma cardiac biomarkers which are the enzymes and proteins that are released in the blood when the cells of the heart die in Myocardial Infarction. These include the cardio-specific Enzyme called the Troponin T and I. The second biomarker here is creatinine kinase (CK-MB).
These molecules are normally in large quantities in the heart cells. Their presence in the blood shows that there is ongoing damage to the heart cells and therefore confirms the diagnosis of Myocardial Infarction.
Other investigations include echocardiography, chest x-ray, and coronary angiography which show a clear picture of the coronary artery and the existing occlusion.
MANAGEMENT OF CORONARY ARTERY DISEASE
Coronary artery disease is an acute emergency. The patient is quickly admitted to the coronary care unit (CCU) and a high concentration of oxygen is given immediately to boost the oxygen supply to the heart cells. The patient is connected to a cardiac monitor and some serial investigations are done to monitor the patient.
The drugs used here are Aspirin which has been found to reduce the risk of adverse outcomes in the patient. Intravenous morphine is given to alleviate pain. Nitrates are given to dilate the vessels and improve blood flow. Other drugs include; beta-blockers, thrombolytic agents (when indicated), ACE inhibitors, antiarrhythmic drugs, etc.
When medical intervention fails, the next options are surgical options which are; Percutaneous Coronary Intervention(PCI) which is a procedure used to open up the blocked heart vessel (coronary artery) and the Coronary Artery Bypass Graft (CABG) where a patent blood vessel is attacked above and below the blocked area to bypass the blockage.
Percutaneous Coronary Intervention
By Scienctific Animations, CC BY-SA 4.0, Wikimedia
OTHER CAUSES OF CARDIAC ARREST
Having discussed coronary artery disease in detail which is the major cause of cardiac arrest, let us just mention some other causes of cardiac arrest. These contribute just a little percentage to the occurrence of the disease.
They include some diseases affecting the structure of the heart like dilated cardiomyopathy where the heart chambers expand and grow bigger, hypertrophic cardiomyopathy where the heart muscles get abnormally thicker, congenital heart diseases, etc.
Other causes of cardiac arrest include severe electrolyte imbalance, drugs, etc.
THE OUTCOME OF A CARDIAC ARREST
Once cardiac arrest occurs, death is almost inevitable unless a prompt intervention is given. Many cases die before getting to the hospital but the good news is that there is a chance for survival if the people there recognize it and act immediately.
That is why it is very important to create awareness. People must know the early symptoms and seek medical intervention. When it occurs, those around must act immediately to save the patient by calling for help immediately, instituting basic life support immediately, and defibrillating the heart. The emergency response of the medical services is also very important.
CARDIOPULMONARY RESUSCITATION (CPR)
This is a basic life skill that everyone must learn which helps in saving those with cardiac arrest. There is training for it, but even without training, a basic knowledge of CPR can be life-saving. However, we are encouraged to acquire this skill as it is indeed essential for those around us.
By Video by Bangkok Hospital Phuket, CC BY 3.0, Wikimedia
In cardiac arrest, once the heart stops beating, brain damage can occur in a matter of minutes which is fatal to the patient. So, cardiopulmonary resuscitation (CPR) is an emergency technique that helps to manually maintain the supply of oxygen-rich blood to the brain and other vital organs to prevent them from being damaged while waiting for the restoration of a spontaneous heartbeat by the medical team. This is achieved using chest compressions and rescue breathing.
Whether trained or untrained, the American Heart Association advises that anyone who witnesses anyone develop cardiac arrest must attempt to rescue the person using CPR.
If you're afraid to do CPR or unsure how to perform CPR correctly, know that it's always better to try than to do nothing at all. The difference between doing something and doing nothing could be someone's life.
The algorithm for basic life support in adults involves checking for the patient's responsiveness by asking the person if he is OK or checking his pulse and breathing. If unresponsive, then immediately call for help. Call 911 or the emergency number applicable to the location. For the untrained persons/by-standers, immediately start chest compressions at the rate of 100 to 120 compressions in a minute.
The hand position for the chest compressions is to place the heel of your one hand at the lower half of the person's breast bone, then place the second hand on the first hand and press down the chest to about one-third of the depth while keeping your arms straight and using your entire body weight. However, avoid going deeper than 6cm.
By BruceBlaus - Own work, CC BY-SA 4.0, Wikimedia
Allow the chest to recoil after each compression. Continue the chest compressions till the medical team arrives. This method is referred to as hands-only compression which is easier to administer.
The trained ones can open the airway and give 2 rescue breaths after every 30 compressions till a defibrillator arrives. If there is no defibrillator, continue chest compressions and rescue breathing till there is a sign of movement or the medical team arrives.
If there is a defibrillator and you are trained on how to use it, apply a shock and continue chest compressions for two minutes, and if after two minutes the pulse is not restored, repeat the shock. The cycle continues till the pulse returns or the medical team arrives.
AED
An automated external defibrillator (AED) is a portable device used to restart the heart by the administration of electric current to correct the abnormal heart rhythm causing cardiac arrest.
By Owain Davies - Own work, CC BY 3.0, Wikimedia
Cardiac arrest from Ventricular fibrillation and pulseless ventricular tachycardia as described above are shockable arrhythmia and can be corrected with AED while Asystole and Pulseless electrical activity (PEA) are non-shockable, here, a precordial thump may be helpful.
PREVENTION
The outcome of cardiac arrest is most times fatal. Therefore, the most important thing here is prevention. We can do this by;
- Eating a healthy diet that is composed of more fruits and vegetables and is low in cholesterol and fats.
- Maintaining a regular weight and regular exercise.
- Avoiding smoking and excessive alcohol consumption
- Maintaining optimum blood pressure and Glucose.
- Avoiding a sedentary lifestyle and going for a regular medical check.
By Ed Yourdon, CC BY-SA 2.0, Wikimedia
In summary, our awareness of how cardiac arrest occurs, its symptoms, and the life-saving skill of CPR are very important to save those around us. Survival from cardiac arrest is possible, but something must be done immediately. You and I can be a savior of someone with cardiac arrest.
The procedure of CPR provided here is not exhaustive. I will advise everyone to take a course on CPR or read further on it.
For further detailed information on CPR, please check the materials below:
American Heart Association
MSD Manual, Professional Version
Red Cross
Thanks so much for reading.
For references and further reading on cardiac arrest and coronary artery disease, please check the materials below: