Tag: adrenaline

Posted in Psychology & Medicine

Viscera: Heart

Posted on by Jinavie

(Learn more about the organs of the human bodies in other posts in the Viscera series here: https://jineralknowledge.com/tag/viscera/?order=asc)

Out of the numerous organs found in the human body, the heart is perhaps the most well-known. This is probably because since the dawn of time, man has put his hand on his chest and felt the rhythmic pounding of his heart – a reminder that he is alive. The function of the heart is to pump oxygenated blood from the lungs to the rest of the body via the circuit of blood vessels (vascular system).

The heart relies on electricity to pump blood in a rhythmic, autonomous way. Because of this property, a heart will beat on its own even if you took it out of the human body. Every muscle in the human body requires an electrical impulse for it to contract. This is also the case in the heart, but unlike the skeletal muscle in other parts of the body which receive their impulses from the brain and spinal cord, the heart has its own source of electricity.

The heart has a small group of pacemaker cells in the right atrium called the sinoatrial node, which always fires electrical impulses at a set rate and rhythm (sinus rhythm). The SA node will do this without any instruction from the brain. The impulse from the SA node spreads throughout the atria of the heart, causing the atrial muscles to contract simultaneously to squeeze blood into the ventricles. The impulses then reach the atrioventricular node, which filters the signals and sends a stream of electricity through a wiring system known as the Purkinje fibres. These fibres act like a high-speed internet cables running down the centre of the heart, sending rapid signals through out the ventricles to induce a strong, cooridnated contraction in both ventricles. This causes blood to be forcefully squeezed out through the two outlet vessels of the heart: the pulmonary artery (to the lungs) and the aorta (to the rest of the body).

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Although the SA node is completely autonomous, it can be controlled using hormones, nerve signals and medications. For example, adrenaline will speed up the rate the heart beats at while massaging the carotid arteries in the neck will slow the heart down.

One thing people wonder about is what the doctors listen to when they put a stethoscope to a patient’s chest. Everyone knows the heart makes a rhythmic “lub dub” sound as it beats away, but what information could that give away? A doctor can gain much information about the heart from a cardiac examination by taking the pulse and blood pressure, but listening to the heart (auscultation) may reveal a medical sign known as a murmur. A murmur is any added sound other than the normal “lub dub” sound of the heart. For example, a heart with aortic stenosis may give the sound “shhhhhhh” as if it was giving off static. This sound is produced when blood flow in the heart is turbulent and not smooth. This may be for a number of reasons but the most common reason is because the valves of the heart are not functioning properly. For example, the valve between the left atrium and left ventricle may be leaky (mitral regurgitation) or the valve at the start of the aorta may be stiff and narrowed (aortic stenosis).

By carefully listening to the sound the heart makes, an experienced doctor may pick up on such structural abnormalities even without the use of fancy medical imaging technologies.

Posted in Psychology & Medicine

Lazarus

Posted on by Jinavie

In the New Testament of the Bible, there is a scene where Jesus resurrects a man by the name of Lazarus back four days after his death. This “miracle” is of course a fictitious event, but nonetheless, the name Lazarus has come to symbolise resurrection after death. For example, there are two actual medical conditions named after Lazarus, both related to death.

The first is called Lazarus phenomenon, where a person who is declared to be clinically dead spontaneously returns to life. This is an extremely rare event that has only been recorded in about 30 cases. In most of these cases, the patients had suffered a cardiac arrest, with all attempts at resuscitation (e.g. CPR, adrenaline) had failed. Sometime after the person was declared clinically dead (usually around 5~10 minutes), the person’s circulatory system would suddenly start on its own and the person would be “resurrected” (quite literally). In one case, a 61 year-old woman was declared officially dead after her heart stopped and her vitals did not return after continuous resuscitation. At the morgue, however, she was found to have a pulse and breathing on her own. She later sued the hospital for the neurological and physical injury caused by oxygen deprivation during her death. There is even a case report of a patient who returned to life two and a half hours after dying (although he died again 3 weeks later).

Of course, the Lazarus phenomenon is not a miracle. In most cases, it is hypothesised that when resuscitation is attempted then stopped, there is a rare chance of the relieving of pressure causing blood to fill the heart, causing a sudden expansion and kickstarting the electrical circuit. Other factors that may influence this is hyperkalaemia resulting from ischaemia and high doses of adrenaline given to the patient during resuscitation having a delayed effect.
Because of this rare “complication” of death, doctors are advised to observe the patient for about 10 minutes after declaring them dead. Just in case.

The second is called Lazarus sign and it occurs not in dead patients, but brain-dead patients. Brain-dead patients are immobile as their higher functions such as cognition and motor functions are destroyed. However, there are rare cases where the brainstem is somehow stimulated, triggering a reflex arc from the spinal cord. This reflex is seen as the patient suddenly raising their arms and dropping them on their chest in a crossed position, much like Egyptian mummies. As the spinal cord is not usually damaged in brain-dead patients, this reflex arc is possible, similar to a knee jerk reflex. The Lazarus sign should not be misinterpreted as a sign that a brain-dead patient is conscious, as it is an involuntary movement. However, it has been mistaken for the resuscitation of a patient, or in some cases, as a miracle.

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Posted in Psychology & Medicine

Broken Heart Syndrome

Posted on by Jinavie

Countless novels and films depict a character, heartbroken from the loss of a loved one or due to a break-up, suddenly clutch their chest and collapse. Although this may seem like a dramatic plot device, it is actually possible to die from stress.

The condition, colloquially termed broken heart syndrome for obvious reasons, is known as takotsubo cardiomyopathy or stress-induced cardiomyopathy. As the name suggests, the heart suddenly goes into congestive heart failure after sudden emotional stress. In simpler words, the heart’s ability to pump blood is sharply reduced due to muscle weakness and blood is not circulated properly. This causes blood to dam up and cause symptoms such as chest pain, breathlessness, fluid overload and much more.

The characteristics of this disease is that the heart temporarily enlarges so that the tip (apex) bulges out while the function of the base (upper part of the heart) is normal. The muscles in the apex is thinned while the base has hypertrophied and thickened. This gives the appearance of a thin pocket with a thick entrance, thus giving the name takotsubo cardiomyopathy, which means “octopus trap” in Japanese.
Given the patient survives the initial heart failure, their condition improves over the course of two months. The patient may also need psychiatric help or antidepressants and sedatives to ease the stress that led to the heart failure. 

As the presentation is very similar to a normal myocardial infarction (“heart attack”), the diagnosis may be difficult. The cause has not been identified yet, but researchers believe it to be due to a combination of blood vessel spasms disrupting blood supply to the heart and high levels of catecholamines. As catecholamines (adrenaline/noradrenaline) are released in great quantities in times of stress, this theory has some plausibility. A similar thing happens when patients with heart problems are exposed to significant levels of fear – their heart goes into overdrive and develop cardiac arrest due to an exacerbation of their condition.

The concept of dying from intense emotions such as anger and stress is found in almost every culture, where a person collapses and falls deathly ill after shocking news or a particularly stressful experience. But modern medicine has only just begun to understand the scientific reasoning behind this strange phenomenon.

It has also been noted that takotsubo cardiomyopathy tends to affect post-menopausal women, especially widows. Interestingly, most of these patients are not considered “at risk” for a heart attack and generally healthy. 
Thus, stress alone can be enough to “break” someone’s heart and cause sudden death.

(Source: http://sndr.deviantart.com/art/Broken-Heart-7445432?q=boost%3Apopular%20broken%20heart&qo=0)

Posted in Psychology & Medicine

Flatline

Posted on by Jinavie

When people think of the word “flatline”, they immediately visualise a medical crisis where a patient is lying unconscious, with doctors and nurses shouting out medical terminology while administering drugs, all to the suspenseful music and apathetic monotone and single horizontal line on the ECG machine. The doctor then shouts “Clear!” and proceeds to shock the patient with two paddles. This is repeated until some structures appear on the ECG, symbolising that the crisis has been resolved.

Of course this is a scene from a typical medical drama. Television shows, especially medical ones, are notorious for sacrificing medical accuracy for the sake of drama and tension. The “flatline” is the most cliché, repeated mistake made by almost every medical television show ever made.

The proper terminology for a flatline (a colloquial term), is asystole. This means that there is no systole, or contraction of the heart. An ECG (electrocardiogram) measures electrical signals in the heart, and in asystole there is insignificant amounts of electric activity, and the classic QRS complex is not seen. In this state, the heart is not pumping any blood and is electrically silent, meaning that the patient is clinically dead.

When asked how to treat this condition, the majority of people (even medical students) will shout “Shock!” or “Defibrillate!”. Defibrillation is the administering of an electrical shock to try “reboot” the heart, and correct the fibrillation – the chaotic electrical signal interfering with the normal, rhythmic electrical activity. Unfortunately, this is completely wrong yet so often depicted on television and films.
As asystole is a state of no electrical activity, there is no fibrillation to remove, nor is there anything to reset. Defibrillation in this state may even cause harm, causing tissue damage and lowering the chance of survival.

The correct treatment is injecting adrenaline (epinephrine in the U.S.A, atropine may be administered also) and CPR. Unfortunately, asystole is a condition that cannot be reversed, unless the heart somehow restores its own electrical activity. CPR merely keeps the patient’s perfusion going to preserve the organs for a longer time. Ergo, asystole signifies certain death, especially after 5 minutes where the heart will not respond to any drugs or electric shocks. In fact, asystole is one of the conditions required for the certification of a patient’s death.

Another related example of a (potentially fatal) misrepresentation of medicine in the media is the adrenaline injection. As mentioned before, this is the treatment for asystole. However, it is administered intravenously (into a vein) and never directly into the heart as in Pulp Fiction. This is more likely to kill the patient than save them, as the heart muscles could be damaged and delicate coronary arteries may become ruptured.

So why is it that the media continues to depict such blatant errors, that set a “common sense” that affect even medical professionals? This is most likely due to the audience wanting to see a dramatic scene, in a gripping life-or-death situation with drastic, powerful action. For example, the audience would much rather see the use of paddles or a giant needle being stabbed into the patient than seeing continuous CPR with no showy movements.

The next time you watch a medical television show, count how many times the doctors try to defibrillate a flatline.

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